Biliary Tract Surgery: Application of Digital Technology 9813367687, 9789813367685

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Chihua Fang Wan Yee Lau Editors

Biliary Tract Surgery Application of Digital Technology

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Biliary Tract Surgery

Chihua Fang  •  Wan Yee Lau Editors

Biliary Tract Surgery Application of Digital Technology

Editors Chihua Fang Hepatobiliary Surgery Zhujiang Hospital of Southern Medical University Guangzhou China

Wan Yee Lau Chinese University of Hong Kong Princecss of Wales Hospital Hong Kong China

Translator Sai Wen Hepatobiliary Surgery Zhujiang Hospital of Southern Medical University Guangzhou China

ISBN 978-981-33-6768-5    ISBN 978-981-33-6769-2 (eBook) https://doi.org/10.1007/978-981-33-6769-2 Jointly published with People’s Medical Publishing House, PR of China © People’s Medical Publishing House, PR of China 2021 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publishers, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publishers nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publishers remain neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Foreword I

“Workers must first sharpen their tools if they want to do well.” What is digitization? It is a science and technology that can be used to deal with many different real things through inputting the number symbols of 0 and 1, after being processed by superb computer programming technology. This cutting-edge science and technology is adopted in Biliary Tract Surgery: Application of Digital Technology. In this book, digital 3D images, visualized diagnosis and treatment, surgical navigation, 3D printing, and indocyanine green fluorescent imaging are used, which pioneers the diagnosis and treatment of biliary tract surgical diseases with precision and minimal invasiveness. “Practice a thousand songs and then know the sound, observe a thousand swords and then recognize the device.” On the occasion of the publication of this book, the “foreword” of this monograph gave us the inscribed feeling: “It is important to know that bliss in the fairyland, cultivation comes from hardship.” Together with this monograph, Digital Liver Surgery and Digital Pancreatic Surgery, these three cutting-edge monographs on vital organ surgery in the upper abdomen are the achievements of Prof. Fang’s team. Over the past 15 years, they have undergone “rope sawing” and “water droplets through stone” and achieved the result of “the fragrance of plum blossom coming from bitter cold.” “If you want to be a thousand miles away, go to the next level.” The biliary tract is a group of functionally specific systems with the smallest diameter among the four types of ducts in the liver. It is more difficult to image and 3D reconstruct the biliary tract compared to the portal vein, hepatic vein, and hepatic artery. Especially in the pre-cancerous stage, the biliary tract has been twisted, deformed, dilated, and narrowed, and pathological changes of the adjacent liver tissues such as necrosis, hyperplasia, fibrosis, atrophy, and hypertrophy may occur. With ingenuity and dexterity, contemporary doctors must conceive ingeniously and climb high and far, so that they can “be ignorant of floating clouds to cover their eyes and be at the highest level” and strive to practice new mission and new deeds in the new era. “After all the flowers are collected into honey, for whom is the hard work and sweet for whom.” Fang’s team has developed independent intellectual property rights: a 3D visualization system software for abdominal medical images, a multifunctional virtual surgical instrument simulation system, and a surgical platform. These software and devices assist the communication of professional workers for preoperative evaluation, plan formulation, and surgical operations. This technology has been promoted and applied in more than 500 hospitals in China. This book is suitable for undergraduate and graduate students to study, reference, and use, which is conducive to accelerating the growth of surgeons. I wrote the forward on the day the book was completed. Shizhen Zhong Academician of the Chinese Academy of Engineering Director of the Institute of Clinical Anatomy, Southern Medical University Guangzhou, China October 10, 2020

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Foreword II

Surgeons pursue the precise and quick implementation of hepatobiliary surgery, so as to relieve the patient’s distress and promote rapid postoperative recovery. Whether the operation can be performed precisely and accurately is determined not only by the exquisite surgical technique, but also accurate understanding and judgment of the size, the range of invasion, the structure of adjacent ducts, and the degree of invasion of tissues and organs. In the past, surgeons relied on 2D imaging data to obtain abstract three-dimensional understanding of them and their experience. Due to the limitations and uncertainties of experience, it is difficult to obtain satisfactory diagnosis and treatment effects. Fine surgical anatomy is always the cornerstone of the success of precise surgical operations. Today, in the era in which modern bioinformatics technology, surgery and anatomy, imaging, computer science, and molecular imaging technology are highly integrated, the fineness of anatomy and the precision of surgery can be visualized before and during surgery, thereby reducing the blindness and risk of exploration, and unveiling the mystery of difficult hepatobiliary surgery. Biliary Tract Surgery: Application of Digital Technology is loaded with such a background and stands out. At the beginning of the twenty-first century, Prof. Fang began to explore the development path of interdisciplinary integration of hepatobiliary-pancreatic surgery and digital medicine under the guidance of his tutor Academician Shizhen Zhong. He closely integrates clinical reality and always adheres to the research aims of “using modern digital medical imaging technology to solve the need for precise clinical surgical evaluation.” In order to break through the bottlenecks in imaging the low-pressure biliary system, he applied for the national “863” project. With the support of this project, he organized a multidisciplinary team involving professionals in surgery, anatomy, imaging, and informatics, developed a 3D visualization system for abdominal medicine with independent intellectual property rights, and constructed the theory and scientific diagnosis and treatment methods of 3D visualization of hepatobiliary-­ pancreatic diseases. Through his personal practice and continuous review and exploration of successful experience, he has published his research results regularly in influential journals. Immediately afterward, he has further condensed and sublimated these reports into a theoretical system and compiled monographs with brand-new concepts such as Digital Liver Surgery and Digital Pancreatic Surgery. This book, the third monograph compiled by Fang’s team, was reviewed by Academician Shizhen Zhong, edited by Prof. Chihua Fang and Academician Wan Yee Lau. The first part is a general introduction. It separately elaborates the digital human biliary system tomographic anatomy, biliary system cast anatomy, and individualized liver ducts, from aspects including 3D printing of biliary diseases, virtual simulation surgery, 3D laparoscopy, molecular imaging, and endoscopic technology; it also involves the new theory of 3D visualization of biliary tract diseases and constructed new technologies and methods of 3D visualization of biliary diseases and 3D printing technology. The second part is a monograph, focusing on the clinical application of 3D visualization technology in biliary diseases, including the 3D visualization, diagnosis, and treatment of diseases such as gallbladder diseases, biliary stones, and biliary tumors, and the forming of a 3D precision diagnosis and treatment system for biliary diseases such as complex hepatolithiasis and hilar cholangiocarcinoma.

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“The sword’s edge is sharpened by itself, and the fragrance of winter plum comes from the bitter cold.” The successful publication of this book has condensed the forward thinking and hard work of the team led by Prof. Fang through long-term clinical practice. However, the development process of digital clinical surgery toward a new scientific peak has only just begun. How to better apply and develop this technology so that the 3D accurate assessment of apparent morphology will leapfrog the development of the 3D accurate assessment of molecular pathology remains an important task before us. We look forward to the continuous efforts of Fang’s team to cast a solid foundation stone and pave the way for the development of digital hepatobiliary surgery in the new era and I hereby write this preface. Mengchao Wu Academician of the Chinese Academy of Sciences Professor of Surgery Eastern Hepatobiliary Surgery Hospital, Second Military Medical University Shanghai, China October 18, 2020

Foreword II

Foreword III

Not long ago, Prof. Fang gave me two books compiled by his team, Digital Liver Surgery and Digital Pancreatic Surgery. After I read them, I felt refreshed. A distinctive feature of the modern medical science and technology in the twenty-first century is the interdisciplinary mutual penetration and integration of biological technology, informatics technology, imaging technology, and medical science and technology, which greatly enriches and changes thinking modes and opens up people’s broad vision of understanding and transforms the world from a new perspective. I have been a surgeon for half a century and have experienced the development of surgery. I deeply feel that the development of surgery is inseparable from anatomy. Surgical anatomy is the foundation of surgery. Fine surgical operations depend on fine surgical anatomy. In such a new era of interdisciplinary integration and mutual promotion of development, the development of surgery has also entered the era of digital anatomy from the traditional anatomy era. In the past, the preoperative and intraoperative judgment of disease was based on the traditional two-dimensional imaging diagnosis and treatment. Now, we have entered a new mode of 3D visualization and precise diagnosis and treatment. It has brought about a major change in our traditional surgical technology. The monographs of Prof. Fang Chihua reflect the spirit of this era. In the early twenty-first century, Fang’s team took the lead in climbing to the peak of digital hepatobiliary and pancreatic surgery in China. Responding to the urgent clinical needs, they innovatively studied the new theory and technologies of 3D visualization and precise diagnosis and treatment of hepatobiliary and pancreatic diseases, and applied them to clinical practice, which has realized the digital anatomy, diagnostic programming, and visualization of hepatobiliary and pancreatic diseases, improved the accuracy of diagnosis of hepatobiliary and pancreatic diseases, and reduced surgical complications. I have also applied this technology clinically and feel that digital medicine has played a significant role in the advancement of surgery. Recently, Fang’s team has compiled Biliary Tract Surgery: Application of Digital Technology. The biliary tract connects the liver, pancreas, and digestive tract. It has its special tissue structure, blood supply characteristics, and metabolic characteristics. It is difficult and risky to operate. Due to the low-pressure characteristics of biliary fluid mechanics, it is difficult to achieve 3D stereo imaging, especially difficult to present 3D imaging of blood vessels simultaneously. Therefore, it has always been a bottleneck restricting accurate preoperative assessment and accurate intraoperative operation. Many surgical decisions depend on explorations during operation, which leads to a certain degree of blindness in results; the high rate of reoperation in biliary surgery is also related to this issue. Fang’s team grasped this core issue and organized a multidisciplinary team to research on this issue. After more than 10 years of research, they finally achieved breakthrough progress and successfully constructed a digital three-dimensional visualization precision evaluation platform for biliary surgery and a preoperative virtual surgery platform. The construction and implementation of this platform freed the hepatobiliary surgeons from the trouble of blind exploration during the operation, improved the radical resection rate of biliary tumors and the surgical cure rate of hepatobiliary calculi, and brought good news to the recovery of patients. All of this has been vividly and fully demonstrated in this book.

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What is particularly gratifying is that this monograph comprehensively elaborates the digital human biliary system tomographic anatomy, biliary system casting anatomy, individualized liver ducts, 3D printing of complex biliary diseases, virtual simulation surgery, 3D laparoscopy, molecular imaging, and endoscopic technology, as well as the three-dimensional visualization and precise diagnosis and treatment theory, platform construction, and application to gallbladder diseases, biliary calculi, biliary tumors, and other diseases. The editor also used paper, video, and other media, fusing writing modes to specifically show the various types of hepatobiliary ducts, vascular classification, disease classification, how to build a three-­ dimensional visualization platform for biliary diseases, how to implement virtual surgery, how to make surgical decisions based on platform evaluation, and specific instructions during surgery, etc., to make high-tech digital three-dimensional virtual reality possible. The visual diagnosis and treatment platform has become close to the clinic, practical, easy for clinicians to master and use, and truly a sharp sword to guide clinicians to accurately perform complex biliary surgery and improve surgical treatment effects. I sincerely appreciate the innovative achievements made by Prof. Fang and his young team for the cause of digital surgery in our country, and I look forward to his continuous efforts to overcome difficulties and rise to the top. Therefore, I wrote this preface. Jieshou Li Academician of the Chinese Academy of Engineering Professor of Surgery General Hospital of Eastern Theater Command Nanjing, China October 19, 2020

Foreword III

Foreword IV

The twenty-first century is a new century in which surgery penetrates and integrates with biology, informatics biology, informatics, and imaging. It is a new century in which various new concepts, technologies, and equipment are constantly introduced, with the aim of “minimizing patient injury and accelerating patient rehabilitation.” The intersection of digital medicine and clinical surgery is a profound revolution in the twenty-first century in which information engineering and medical technology break through their stereotypes and innovate. The creation of a series of new instrumentation and technologies including surgical navigation, 3D reconstruction, 3D printing, virtual simulation surgery platform construction, 3D laparoscopic surgery, and robotic surgery is born from the prime intention of the surgeon: to use the most minimally invasive technical means to allow patients to receive the best treatment at the least cost, with the least injury, and obtain the best treatment effect. In such an era of technological innovation, we ushered in the publication Biliary Tract Surgery: Application of Digital Technology, Prof. Fang Chihua’s third monograph on digital surgery after Digital Liver Surgery and Digital Pancreatic Surgery. The biliary tract has its special tissue structure and blood supply and metabolism characteristics. The slender and complicated bile tree inherits the liver and pancreas, the two most important metabolic organs of the human body, and is connected to the intestine. Biliary surgical diseases are common and frequently occur in China. Diseases such as cholelithiasis and hepatolithiasis, or diseases with poor prognosis and difficult treatment, such as gallbladder cancer and hilar cholangiocarcinoma, seriously endanger people’s health. In the past, due to the low-pressure hydrodynamic characteristics of the biliary tract, its three-dimensional reconstruction was difficult to present simultaneously with the blood vessels. By only relying on inspection methods such as B-ultrasound, CT, and MRCP, it was difficult to accurately evaluate the diagnosis before surgery, resulting in unsatisfactory treatment effects. For example, in the past, the residual stone rate of hepatolithiasis was as high as 20–50%. Many patients suffered from multiple operations, but the disease has not yet been cured, and eventually they are on the road to end-stage bile disease. Therefore, Academician Huang Zhiqiang has repeatedly called for surgeons to use the “third eye,” “third hand,” and “sixth sense” to explore the secrets of complicated biliary trees and strive for the success of difficult biliary surgery. “Let the patient live happily, and this is the most important thing.” Prof. Fang has been committed to clinical research on the application of digital medical technology in hepatobiliary and pancreatic surgery for nearly ten years under the guidance of his tutor Academician Shizhen Zhong. Supported by the National Eleventh and Twelfth Five-­ Year “863” plans and major special projects of Guangdong Province, he organized a multidisciplinary team to develop a 3D visualization system for abdominal medical images with independent intellectual property rights, and built the theory of hepatobiliary and pancreatic diseases, which has greatly improved the accuracy of disease diagnosis and effectively reduced surgical complications. This book is accompanied by pictures and texts, which introduces the latest knowledge in all aspects of digital human biliary system tomographic anatomy, biliary system casting anatomy, and individualized liver ducts, as well as 3D printing of biliary diseases, virtual simulation surgery, 3D laparoscopy, molecular imaging, and endoscopic technology. This book demonstrates the application of 3D visualization technology to guide the xi

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technical essentials of surgical treatment of gallbladder diseases, biliary stones, and biliary tumors. The content is rich and detailed, the production is smooth and exquisite, and the book has high academic value. This monograph can be used not only for doctors at all levels in general surgery, hepatobiliary surgery, imaging, and biomedical engineering clinical directions but also for graduate students and undergraduates to understand the application of digital medicine in clinical surgery. This book can help them understand the rich connotation of digital medicine in clinical surgery, enlighten their innovative thinking, and help young scholars to learn and progress in today’s rapidly changing era of biological intelligence information. In view of the fact that digital medicine has become one of the future development directions of general surgery in China, I sincerely recommend this book to readers, and I wish Prof. Fang’s team new achievements in the march toward digitalized hepatobiliary and pancreatic surgery. Yupei Zhao Academician of the Chinese Academy of Sciences Professor of Surgery Peking Union Medical College Hospital, Beijing, China October 19, 2020

Foreword IV

Preface

In the new era of digital medicine, the application of new technologies represented by 3D printing, big data, artificial intelligence, radiomics, and photoacoustic imaging of tumor boundary ushered in the publication of this book. There is an old Chinese proverb, “when you drink water, think about the source.” In 2002, the author started the research on segmentation, registration, and 3D reconstruction of the image data of the liver, biliary tract, and pancreas under the guidance of Academician Shizhen Zhong, the famous clinical anatomist. It has been 18 years. During this period, our team has (1) developed a 3D visualization system for abdominal medical images (software copyright 2008SR18798) and a virtual surgical instrument simulation system (software copyright 2008SR18799). Both have certifications from China’s National Medical Products Administration. (2) Put forward the theory of 3D visualization, and innovatively built the core technology and system for 3D visualization and accurate diagnosis and management of complex hepatobiliary and pancreatic diseases, including 3D visualization and precision diagnosis and treatment platforms for complex liver cancer, central liver cancer, hepatolithiasis, hilar cholangiocarcinoma, and pancreatic cancer, respectively. (3) Compiled and published the first set of internationally applicable specifications, operating guidelines, and consensus recommendations. (4) Proposed and established the concept of digital intelligence diagnosis and treatment technology and utilized this technology primarily for the diagnosis and management of liver cancer, which was published in The Lancet’s EBioMedicine. This technology is based on 3D visualization, combined with 3D printing, virtual reality, augmented reality, mixed reality, fluorescent navigation, real-time image fusion, and photoacoustic imaging for precise diagnosis and treatment of primary liver cancer. (5) Developed a novel laparoscopic hepatectomy navigation system, the LHNS, to address the issue of intraoperative multimodal non-rigid registration of the liver. (6) Pioneered the use of digital intelligent technology to navigate anatomical, functional, and radical hepatic resection for primary liver cancer, using computer-assisted indocyanine green (ICG) fluorescent imaging. (7) Achieved integration of early diagnosis and treatment of experimental liver cancer by combining photoacoustic imaging and target-specific molecular probes and pushed detection and management of liver cancer from morphological to molecular and cellular levels. In addition, under the funding of the National Science and Academic Monograph Publishing Fund, we published the first international series of Digital Hepatic Surgery, Digital Pancreatic Surgery, and this book. The research results above have won two first prizes and one second prize of Guangdong Science and Technology Progress Awards in 2010, 2019, and 2015, respectively, and the China-­ Industry-­University-Research Collaboration Innovation Award in 2014. Digital medical technology was born in Guangdong, extended and developed across China, and has been promoted and applied in more than 500 hospitals. “Only comparison can distinguish.” Based on the visibility of CT and MRI, 3D visualization technology realizes clearer and more accurate views. It has improved the accuracy of disease diagnosis, effectively reduced the risks and complications of surgery, and truly changed the past “crossing the river by feeling the stones” and realizing the current “crossing the river by watching the stones.” This is the greatest contribution that 3D visualization technology has made to the diagnosis of human surgical diseases. xiii

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“If you don’t have a garden, how can you know how spring is like.” The biliary system is a very important organ of the human body. The upper part connects to the liver and the lower part to the pancreas. It has its unique anatomical position and functional characteristics. Especially the biliary tract tree, once you step into it, it is like entering a “maze.” Therefore, biliary surgery faces great challenges. The breakthrough point of biliary tract surgery is to grasp the complexity and variability of liver vascular structure, especially the biliary system. Although the advancement of modern imaging has promoted the development of hepatobiliary surgery, patients with biliary diseases, such as hepatolithiasis and hilar cholangiocarcinoma, experience a long course of chronic cholangitis and chronic obstruction of the biliary tract before they are clear of symptoms. The biliary structure can be twisted, deformed, expanded, or narrowed, and pathophysiological changes such as necrosis, hyperplasia, fibrosis, atrophy, or hypertrophy can occur in the adjacent liver tissue, which may increase the difficulty in identifying the very complex intrahepatic bile duct system and add uncertainty to the preoperative assessment of blood vessels, bile ducts, and their relationship with the lesion. Even modern imaging techniques sometimes seem pale and weak. We feel deeply that the 3D visualization of biliary surgery disease is far more difficult than 3D visualization of the liver and pancreas. “The source of living water is full everywhere, and the east wind and the flowers will change with the times.” It is an important task for a scientist to determine how to use digital medical technology to guide the precise diagnosis and treatment of biliary surgery diseases. Closely focusing on this key issue, with clinical needs as the driving purpose, and from a clinical perspective, 15 years ago, we innovatively pooled experts in the fields of hepatobiliary surgery, imaging, anatomy, computer image processing, physics, and molecular imaging to carry out research. Complex hepatolithiasis and hilar cholangiocarcinoma are regarded as our main goals. Serendipitously, it has been found that the 3D visualization model of hepatolithiasis can clearly show the size, location, and shape of the stone; the location, length, and degree of the stenosis of the bile duct; and the relationship between the stone and the blood vessel. It has provided a solid foundation for subsequent preoperative planning and selection of surgical methods. The 3D visualization model of hilar cholangiocarcinoma accurately displays the relationship between the location of cholangiocarcinoma and the portal vein and hepatic artery, and accurately evaluates the positions of P and U points (the limit point of bile duct separation) enabling the classification of hilar cholangiocarcinoma and whether it can be resected. The result is unparalleled by other imaging inspection methods. Firstly, we have achieved a series of new methods of targeting lithotripsy guided by three-dimensional visualization, which overcomes the problem of high residual stone rate after surgery. Secondly, we have proposed the concept of “digital minimally invasive technology” and applied it to the practice diagnosis and treatment of hepatobiliary stones, realizing the digitalization of minimally invasive diagnosis and treatment of biliary surgical diseases. Thirdly, we have established the 3D visualized clinical classification of hilar cholangiocarcinoma, which truly achieved “crossing the river by watching the stones.” Fourthly, we achieved anatomical, functional, and radical hepatic resection for hilar cholangiocarcinoma by using 3D visual morphological precision assessment technology with the indocyanine green fluorescent molecular imaging diagnostic technology. “One leaf in the boat will bring spring scenery to the south of the Yangtze River.” This book was reviewed by Academician Shizhen Zhong, edited by Prof. Chihua Fang and Academician Wan Yee Lau, and prefaced by Academicians Mengchao Wu, Jieshou Li, Shizhen Zhong, and Yupei Zhao. The key chapters and sections of this monograph have been integrated and compiled by media such as paper, animation, 3D, and surgical videos. During the reading process, the reader can click on the relevant media to see the exquisite 3D pictures and surgical videos which are faithful to the patient’s disease. “Generally, the roots are in the soil, and each will wait for the time.” Through persistent clinical observations and tireless work day and night, our team adheres to scientific and realistic research and humbly sought advice; finally, we completed the publication of this book. This book is a successor to Digital Liver Surgery and Digital Pancreatic Surgery, another key research monograph on digital medicine. The three sister monographs are the result of research

Preface

Preface

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completed under the funding of the “11th Five-Year Plan” and “12th Five-Year Plan” national “863” project, the “13th Five-Year Plan” National Digital Diagnosis and Treatment Project, and the National Natural Science Foundation of China. “Leave ingenuity alone to pass the ages”—this set of research results using modern high-tech technology, successfully applied to clinical practice formulation and planning, has strong cutting-edge, scientific, practical, and clinical guidance value. This book is not only suitable for reading by hepatobiliary and pancreatic surgery workers but also for undergraduates and graduate students to read, reference, and use, which is beneficial to accelerate the growth of surgeons. Guangzhou, China October 20, 2020

Chihua Fang

Acknowledgments

The authors are grateful to the contributors for their work of editing the Chinese version of this book and collecting pictures, videos, and flow charts. Also, we would like to express our heartfelt gratitude to John Clarke, the British foreign language teacher of Southern Medical University, for his contribution to proofreading and copyediting of this book.

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Contents

1 Applied Anatomy of the Biliary Tract�����������������������������������������������������������������������   1 Jun Ouyang, Chihua Fang, and Min Hu 2 Application of Multi-slice Spiral CT and MRI in Biliary Surgery�������������������������  15 Suisheng Zheng, Xijun Gong, Xuchang Zhang, Yangguang Yuan, Xinming Li, and Chihua Fang 3 Imaging of Common Biliary Tract Diseases�������������������������������������������������������������  31 Xianyue Quan, Shuping Qian, Zhendong Qi, Jingjing Huang, Liying Han, and Chihua Fang 4 Introduction to 3D Visualization of Abdominal CT Images����������������������������������� 101 Susu Bao, Fengping Peng, and Chihua Fang 5 Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery��� 117 Chihua Fang and Zhaoshan Fang 6 Virtual Surgical Instruments and Surgical Simulation������������������������������������������� 131 Susu Bao, Jiahui Pan, Xu Chang, Dongbo Wu, and Chihua Fang 7 Application of Indocyanine Green Fluorescent Imaging in Biliary Surgery��������� 161 Chihua Fang and Wen Zhu 8 Application of Endoscopic Techniques in Biliary Tract Surgery��������������������������� 173 Zhaohui Tang and Chihua Fang 9 Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts����� 185 Chihua Fang, Jian Yang, and Xu Chang 10 Digital Surgical Diagnosis and Management of Cholecystolithiasis ��������������������� 205 Nan Xiang, Songsheng He, and Chihua Fang 11 Digital Surgical Diagnosis and Management of Extrahepatic Cholelithiasis������� 221 Yunqiang Tang, Xu Chang, and Chihua Fang 12 Digital Surgical Diagnosis and Management of Hepatolithiasis����������������������������� 239 Qiping Lu, Jian Yang, Ping Wang, Jun Liu, Yingfang Fan, and Chihua Fang 13 Digital Surgical Diagnosis and Management of Biliary Dilatation ����������������������� 311 Jian Yang, Haoyu Hu, and Chihua Fang 14 3D Visual Diagnosis and Management of Bile Duct Injuries ��������������������������������� 321 Ning Zeng, Silve Zeng, Jian Wang, Jiayan Yan, and Chihua Fang

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15 Digital Surgical Diagnosis and Treatment of Gallbladder Cancer������������������������� 337 Yingbin Liu, Haibin Liang, Jianming Wang, Yan Liu, and Chihua Fang 16 Digital Diagnosis and Management of Cholangiocarcinoma��������������������������������� 363 Feng Shen, Kui Wang, Qifei Zou, Ning Zeng, Xiangcheng Li, and Chihua Fang 17 Application of 3D Visualization Technology in Perihilar Surgery������������������������� 421 Jian Wang, Jiayan Yan, and Chihua Fang

Contents

Editors and Contributors

Deputy Editors Qiping Lu  General Hospital of Central Theater Command, Wuhan, China Xianyue Quan  Zhujiang Hospital, Southern Medical University, Guangzhou, China Jun Ouyang  Department of Anatomy, Southern Medical University, Guangzhou, China

Contributors Susu Bao  South China Normal University, Guangzhou, China Wei Cai  Zhujiang Hospital, Southern Medical University, Guangzhou, China Xu Chang  Panyu District Hospital of Traditional Chinese Medicine, Guangzhou, China Yingfang Fan  Zhujiang Hospital, Southern Medical University, Guangzhou, China Chihua Fang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Zhaoshan  Fang The Fifth Affiliated Hospital of Guangxi Medical University, Nanning, China Xijun Gong  The Second Affiliated Hospital of Anhui Medical University, Anhui, China Liying Han  Zhujiang Hospital, Southern Medical University, Guangzhou, China Songsheng He  Zhujiang Hospital, Southern Medical University, Guangzhou, China Haoyu Hu  Zhujiang Hospital, Southern Medical University, Guangzhou, China Min Hu  Zhujiang Hospital, Southern Medical University, Guangzhou, China Jingjing Huang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Yaohuan Huang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Wan Yee Lau  Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China Xiangcheng Li  The First Affiliated Hospital of Nanjing Medical University, Nanjing, China Xinming Li  Zhujiang Hospital, Southern Medical University, Guangzhou, China Haibin Liang  Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China Yan  Liu Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China

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Yingbin Liu  Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China Jiahui Pan  South China Normal University, Guangzhou, China Fengping Peng  South China Normal University, Guangzhou, China Zhendong Qi  Zhujiang Hospital, Southern Medical University, Guangzhou, China Shuping Qian  Zhujiang Hospital, Southern Medical University, Guangzhou, China Feng  Shen Eastern Hepatobiliary Surgery Hospital, Naval Medical University, Shanghai, China Yunqiang Tang  Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China Zhaohui Tang  Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China Jian  Wang Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China Jianming Wang  Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China Kui  Wang Eastern Hepatobiliary Surgery Hospital, Naval Medical University, Shanghai, China Ping Wang  First Affiliated Hospital, Guangzhou Medical University, Guangzhou, China Dongbo Wu  Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou, China Nan Xiang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Jiayan  Yan  Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China Jian Yang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Junying Yang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Yangguang Yuan  Zhujiang Hospital, Southern Medical University, Guangzhou, China Ning Zeng  Zhujiang Hospital, Southern Medical University, Guangzhou, China Silve Zeng  Zhujiang Hospital, Southern Medical University, Guangzhou, China Peng Zhang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Xuchang Zhang  Zhujiang Hospital, Southern Medical University, Guangzhou, China Xingyang Zhao  Zhujiang Hospital, Southern Medical University, Guangzhou, China Suisheng Zheng  The Second Affiliated Hospital of Anhui Medical University, Anhui, China Wen Zhu  Zhujiang Hospital, Southern Medical University, Guangzhou, China Qifei  Zou Eastern Hepatobiliary Surgery Hospital, Naval Medical University, Shanghai, China

Manuscripts Translation and Preparation Sai Wen  Zhujiang Hospital, Southern Medical University, Guangzhou, China

Editors and Contributors

1

Applied Anatomy of the Biliary Tract Jun Ouyang, Chihua Fang, and Min Hu

1.1

Introduction

Since prevention of injury is of paramount importance, a thorough familiarity with the anatomy and related research methodologies of the biliary system is essential. The technologies developed to produce both physical and virtual three-dimensional (3D) modelling have greatly enhanced the learning process and contribute significantly to patient safety. This chapter will present: • A detailed description of the applied anatomy of the biliary system (such as associated structures and the blood supply). • The method of instillation of the in vitro biliary tract as well as the perfusion of the vascular cast. • The construction steps of the digitized virtual biliary system (liver milling, data acquisition, and 3D reconstruction).

1.2

 pplied Anatomy of the Biliary A System

The biliary system, which is subdivided into intrahepatic and extrahepatic ducts, transports bile secreted by hepatocytes to the duodenum. It originates from the bile capillaries in the liver, and its terminal end joins with the pancreatic duct and then opens into the duodenum at the major duodenal papilla. The intrahepatic bile duct can be divided into segmental bile ducts, sectional bile ducts, and left and right hepatic ducts. The extrahepatic bile duct comprises left and right hepatic ducts, common hepatic duct, gallbladder, cystic duct, and common bile duct. J. Ouyang Department of Anatomy, Southern Medical University, Guangzhou, China C. Fang (*) · M. Hu Zhujiang Hospital, Southern Medical University, Guangzhou, China

1.2.1 Anatomy of Intrahepatic Bile Ducts The intrahepatic bile duct originates from the bile capillary in the liver and then converts into the interlobular bile ducts, segmental bile ducts, sectional bile ducts, and left and right hepatic ducts (Fig. 1.1). The intrahepatic bile ducts run in the portal tract alongside the portal vein radicles and hepatic artery branches (Fig. 1.2), all of which are surrounded by a connective tissue sheath (Glisson sheath). Branches of the intrahepatic bile ducts are generally named based on the lobes and segments of the liver. The term “first-order branches” refers to the left and right hepatic ducts; “second-order branches” refers to the left medial hepatic duct, left lateral hepatic duct, right anterior hepatic duct, and right posterior hepatic duct; and “third-order branches” refers to right anterior hepatic ducts, right posterior hepatic ducts, left medial hepatic ducts, and left lateral hepatic ducts (Kogure et al. 2000).

1.2.2 Anatomy of Extrahepatic Bile Ducts The extrahepatic biliary system consists of the left and right hepatic ducts, the common hepatic duct, the gallbladder, the cystic duct, and the common bile duct (Zhong 1998).

1.2.2.1 The Left and Right Hepatic Ducts and the Common Bile Duct The common hepatic duct is formed by the junction of the left and right hepatic ducts in the depth of the liver hilum. The right hepatic duct usually lies alongside the right transverse groove of porta hepatis, deep in the posterior superior part of the liver. It is thick and short, with the length ranging from 2 to 3 cm, and has an angle of about 150o with the common hepatic duct. The left hepatic duct lies alongside the left transverse groove of porta hepatis, receiving bile from the bile canaliculi in the left caudate process. It is slender and shallow, with the length varying from 2.5 cm to 4 cm and at

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_1

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Fig. 1.1  Adult intrahepatic bile duct cast specimen. (a) Top view, (b) bottom view

a Left lateral segment

Right posterior segment

Left hepatic duct Right hepatic duct

Common hepatic duct Left medial segment

Right anterior segment

b Right anterior segment

Right hepatic duct Right posterior segment

Common hepatic duct Right hepatic duct Left lateral segment Left hepatic duct

Fig. 1.2  Cast specimen of adult liver ducts. Note: Green for biliary tract and hepatic duct, blue for hepatic vein, red for hepatic artery, and yellow for portal vein

Hepatic vein Proper hepatic artery

Portal vein

Hepatic duct and biliary tract

an acute angle with the common hepatic duct. It is usually formed by the convergence of the right anterior sectoral ducts (RASD) and right posterior sectoral ducts (RPSD). Variations of the hepatic duct and its branches are exceedingly common. Accessory hepatic ducts can occasionally be discovered, mostly an accessary right hepatic duct, which often exits the liver at the liver hilum and confluent with the hepatic duct, the cystic duct, or the common bile duct (Couinaud 1989). Within the porta hepatis, the hepatic duct, the portal vein, and the hepatic artery are closely related. Typically, the left and right hepatic ducts travel in the front, the left and right hepatic arteries in the middle, and the left and right branches of the portal vein in the rear. The proper hepatic artery divides into left and right hepatic arteries before entering the porta hepatis, but the point at which it gives rise to the left

and right hepatic arteries is low; the portal vein bisects into the left and right branches, and the junction forms at a slightly higher point; while the union of left and right hepatic ducts was found to be superior to the hepatic arteries. The common hepatic duct is usually located in the right anterior part of the hepatoduodenal ligament; it measures approximately 2–4 cm in length with a diameter of 0.4–0.6 cm. The inferior aspect of the common hepatic duct then joins the cystic duct coming from the gallbladder to form the common bile duct (Fig. 1.3).

1.2.2.2 Gallbladder The gallbladder is a pear-shaped and thin-walled saccular structure located in a shallow fossa on the visceral surface of the liver, in line with the interlobar fissure that separates the two hepatic lobes. It measures approximately 8–12  cm in

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Fig. 1.3  Extrahepatic bile duct Calot triangle Cystic artery Neck of gallbladder

Common hepatic duct

Cystic gall duct

common bile duct

Fig. 1.4  Composition of the ampulla of Vater

Cystic gall duct Sphincter of common bile duct Main pancreatic duct Major duodenal papilla

Sphincter of pancreatic duct

Vater ampulla sphincter Pancreas Vater ampulla

length, 3–5 cm in diameter, and 40–60 ml in capacity when fully distended. The gallbladder is divided into three sections: the fundus, body, and neck. The gallbladder fossa projects upward, backward, and to the left, and eventually tapers at the neck. At the junction of the neck of the gallbladder and the cystic duct, a dilatation or pouch may appear, known as ampulla of gallbladder (Hartmann’s pouch). Gallstones commonly impact this sac, producing obstruction and acute cholecystitis.

1.2.2.3 Cystic Duct The cystic duct extends from the neck of the gallbladder. It is typically 0.3 cm in diameter and about 2–3 cm long. Spiral mucosal folds, referred to as valves of Heister, are present in the proximal mucosa of the cystic duct, which regulates the bile flowing in and out of the gallbladder and prevents the distortion of the gallbladder duct; while the proximal mucosa of the common hepatic duct shows a smooth manner. Gallbladder hydrops can occur when bile duct inflammation causes edema of the Heister valves, or when large stones are incarcerated. The cystic duct merges with the common hepatic duct to form the common bile duct, while the position and entry of the cystic duct into the ductal system are variable. It can run

anteriorly or posteriorly and enter the left side of the common hepatic duct, it can be fused to the right hepatic duct or left hepatic duct, it can also run parallel and enter it more distally. Calot’s triangle is a triangular space bordered by the cystic duct inferiorly, common hepatic duct medially, and the inferior edge of the liver superiorly; it is of particular importance surgically because it contains the cystic artery, the right hepatic artery, and accessory right hepatic duct. This anatomical space requires careful dissection during cholecystectomy to avoid injury (Fig. 1.3).

1.2.2.4 Common Bile Duct The common bile duct is formed by the junction of the cystic duct and the common hepatic duct. It measures typically about 7–9  cm in length and about 0.6–0.8  cm in diameter. The duct can be divided into four portions according to its course and relationships (Fig. 1.4). Supraduodenal Portion The supraduodenal portion begins at the confluence of the common hepatic and cystic ducts and ends at ampulla of Vater in the second part of the duodenum at the major duodenal papilla. This portion lies anterior to the portal vein, to the

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right of the hepatic artery proper, and descends along the right edge of the hepatoduodenal ligament. This segment is relatively easy to expose; via which laparoscopic common bile duct exploration, T-tube drainage, choledochoscopy with stone extraction, and Roux-en-Y anastomosis are often performed. Retroduodenal Portion The common bile duct passes behind the superior part of the duodenum, with the inferior vena cava on its posterior aspect and portal vein and gastroduodenal artery (GDA) on its left. Pancreatic Portion The common bile duct descends through a groove placed on the posterior aspect of the pancreas or within the pancreatic substance. This portion begins at the head of the pancreas and ends at the duodenum wall. This segment is difficult to expose during the operation. In order to reveal it, the posterior peritoneum of the lateral duodenum must be dissected, and the duodenum and pancreatic head be removed and turned inward. Intraduodenal Portion This course is 1.5–2 cm in length, in which the common bile duct passes obliquely through the middle of the medial border of descending duodenum. In 85% cases, the common bile duct and main pancreatic duct pierce the duodenal wall and unite to form a dilated common channel, known as the ampulla of Vater (Ramesh and Sharma 2014). The ampulla of Vater protrudes into the duodenum lumen, and the elevation of the duodenal mucosa forms the major duodenal papilla, opening to the posterior medial wall of the descending duodenum. At the exit, a small complex of smooth muscles, known as the sphincter of Oddi, surround the ampulla, terminal parts of the common bile duct, and the main pancreatic duct. The duodenal papilla is generally 2 mm in diameter, 3 mm in height, and 4 mm in width, located in the middle third of the descending duodenum. In another 15–20% cases, they have separate openings for the bile duct and the main pancreatic duct (Misra and Dwivedi 1990). The sphincter of Oddi is a crucial structure regulating the pressure in the bili-

ary system. It controls the openings of the common bile duct and the pancreatic duct and also prevents the regurgitation of duodenal contents into the biliary tract. The main structures of the hepatoduodenal ligament include the common bile duct, hepatic artery proper, and portal vein. The common bile duct lies in the ligament’s right edge, the hepatic artery proper lies to the left, and the portal vein lies posteriorly; hepatic arterial anomalies may occur. The replaced right hepatic artery usually arises from the superior mesenteric artery and the gastroduodenal artery, which has a tremendous guiding value for surgery. The blood supply of the gallbladder is derived from the cystic artery, which originates approximately 85% of the time from the right hepatic artery and most of which commences within the Calot’s triangle. However, there is great variation in the course and origin of the cystic artery. It may also arise from the gastroduodenal artery, right, left, and middle hepatic artery or hepatic artery proper originating from the superior mesenteric artery (Fig. 1.5). Venous drainage is via the cystic veins, which join the right branch of the portal vein. Note, some parts of the small cholecystic venous branches enter the liver directly through the liver bed and flow into the hepatic vein. The blood supply to the hepatic ducts, cystic duct, and the upper portion of the common bile duct is the cystic artery. The blood supply to the medial aspect of the common bile duct is to the right of the hepatic artery proper. The lower part of the common bile duct is supplied by the branches of the gastroduodenal artery and posterosuperior pancreaticoduodenal artery. Fine branches from the arteries mentioned above, form a reticular epicholedochal venous vascular network on the surface of the common bile duct and anastomose with each other to form plexuses. These arteries confluence into two axial vessels at the 3 o’clock and 9 o’clock positions of the bile duct wall and have an axial course supplying the bile duct. The veins of each bile duct segment converge directly into the portal vein or quadrate lobe of the liver (Figs. 1.6, 1.7, and 1.8). Lymphatic drainage: Lymph drains into the cystic lymph node, which empties into the hepatic lymph node. The lymph nodes of the gallbladder are mainly lymph nodes that meet at the junction of the cystic duct and the common hepatic duct.

Fig. 1.5  The cystic artery originating from the right hepatic artery

Cystic artery Right hepatic artery

Left hepatic artery Proper hepatic artery

Gastroduodenal artery

Common hepatic artery

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The lymph nodes in the upper part of the bile duct merge into the lymph nodes of the gallbladder, the lymph nodes of the liver, and the lymph nodes of omental foramen. The lymph of the gallbladder and the lymph of the liver combine and drain to the lymph nodes next to the common bile duct in the duodenum, which is accompanied by the hepatic artery to the peripheral lymph nodes around the celiac artery. The lymphatics in the lower bile duct are drained to the pancreatic lymph node and then drain along the axis of the hepatic artery to the lymph nodes around the celiac artery. Innervation: It mainly refers to the afferent fibers of the sympathetic and vagal nerves in the celiac plexus, both of which are distributed in the gallbladder and bile duct; with the branches of the hepatic artery passing through the hepatic plexus. Parasympathetic stimulation produces gallbladder contraction and sphincter of Oddi relaxation, allowing bile outflow into the duodenum, while stimulation of the sympathetic nerve has the reverse effect (Zhong 1998).

Right hepatic artery

Cystic artery

Fig. 1.6  Cast anatomy of cystic artery

Fig. 1.7  Blood supply of common bile duct

Common bile duct

3 o'clock artery

Anterior T-shaped arterial network of the common bile duct 9 o'clock artery

Gallbladder

Common hepatic duct

Cystic artery Right hepatic artery Duct of gallbladder Common bile duct Gastroduodenal artery

Left hepatic artery Proper hepatic artery Common hepatic artery Pancreas

Superior mesenteric artery

Fig. 1.8  Intrahepatic and extrahepatic biliary system and the accompanying arteries

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The composition of the gallbladder wall: • Mucosa: The mucosa is lined by columnar epithelial cells with absorption function and contains specialized tubuloalveolar mucous glands that secrete sticky mucus. The gallbladder mucosal is variably folded, which increases the total surface area for inspissating bile. • Muscularis externa: Consists of the thick inner longitudinal, the outer circular, and the middle elastic fibrous tissues. • Adventitia: Adventitia is made up of a thick layer of connective tissue, and a layer of mesothelium covers adventitia on the free surface. The composition of the extrahepatic bile duct wall: • Mucosa: The mucosa contains such mucous cells as goblet cells that secrete mucus. • Smooth muscle and elastic fiber layer: Stimulation causes spasmodic contraction of the muscle fibers. • Serosa: The serosa is made up of a layer of connective tissue rich in nerves and blood vessels.

1.2.3 Anatomy of the Biliary Cast Tremendous advances in medical technology and update of medical equipment have driven the field of modern surgery forward into the current minimally invasive approaches and precision procedures. Moreover, the development of surgical navigation systems, virtual surgery, and robotic surgery have necessitated examining the distribution of small blood vessels in 3D spaces. Accurate surgical treatment has put forward higher requirements for understanding complex intrahepatic anatomical structures, and further strengthening the understanding of it will undoubtedly greatly enhance the therapeutic effect on biliary diseases. The development of biliary surgery has benefited from studies on vascular structures of the liver. The internal vascular and ductal anatomy of the liver is complex (Hjortsj 1951). In recent years, the trend in biliary tract surgery is toward minimal invasive, individualized, and delicate procedures, while precision surgery should be based on advanced anatomical knowledge. Concerning the researches on the anatomy of the liver, the gross anatomy of cadavers, and corrosion cast methods are primarily used (Spitzer et  al. 1996). Meanwhile, the widespread application of digital technology and an increasing number of researches into intrahepatic anatomical structure using these techniques has further deepened people’s understanding of the anatomy of the liver (Figs. 1.9 and 1.10) (Wigmore et al. 2001).

Vascular corrosion casting is a widely used dissection technique in medical education and clinical research, which can visualize the complex three-dimensional structure of the human hepatic vasculature. It resembles casting technology in the industry. However, it is based on the natural vascular or cavity structure in viva (such as blood vessels, lymphatic vessels, ventricles, hepatic ducts, and pancreatic ducts). The vascular structures are perfused with a fixative (such as plastic or denture powder). When the injected substance becomes hard, the specimen is submersed in a strong acid or alkali solution. The tissue is subsequently corroded away, while the hardened cast remains because of its strong acid and alkali resistant properties. The whole process is known as vascular corrosion casting. The casting technique dates back to fifteenth to sixteenth century Italy. The famous painter, Da Vinci, produced a wax cast of cerebral ventricles. Since then, a variety of mold specimens have been produced using materials such as low-melting point alloys and celluloid. By the 1970s, the casting technique had entered a new stage of development thanks to the advances in the modern chemical industry. Many premium-quality plastic products, such as perchloroethylene and styrene, have been utilized as filling materials in the casting process. While perfusing, a low-­ concentration fixative is recommended since the diameter of the bile duct system is relatively small. At the first perfusion, it should be performed after bile is squeezed out through the common bile duct. The bile duct system may not be adequately perfused at one time, and in that case, reperfusion is needed on the post-perfusion day 2 or 3. Anticorrosion and fixation are very important, and the natural shape of the liver should be maintained to avoid deformation under pressure. Bile duct and adjacent structures are fixed.

1.3

I solated Biliary Tract and Vascular Perfusion

Studies on intrahepatic vascular structure have aided advances in biliary tract surgery; further, it has been pushed into a new stage by dramatic improvements in modern imaging modalities (such as spiral computed tomography (CT), and MRI). Nonetheless, biliary tract surgery still faces significant challenges due to the complexity and variability of intrahepatic vascular structure; and lack of sophisticated research on and three-dimensional imaging of it. Currently, with the development of the clinical anatomy of biliary tract and biliary tract surgery, modern imaging techniques as well as their mutual integration, studies have achieved the visualization of image dataset and intrahepatic vessels and simulation of biliary tract operations.

1  Applied Anatomy of the Biliary Tract Fig. 1.9  Perfusion of the gallbladder, bile duct, portal vein, and artery Note: Green for the bile duct and hepatic duct, red for the hepatic artery, white for the portal vein

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a Gallbladder

Right hepatic duct Duct of gallbladder

Left hepatic duct

b

Common hepatic Duct Duct of gallbladder

Common bile duct

c Right hepatic duct Duct of gallbladder

Left hepatic duct Common hepatic duct

Gallbladder

1.3.1 Intrahepatic Vascular Perfusion Technique While studying the biliary perfusion, the other three sets of intrahepatic vasculatures (the hepatic artery, portal vein, inferior vena cava/hepatic vein) should be properly perfused as well (Fang et al. 2007). Satisfactory images of the pipelines should be generated during the CT scan. Based on CT values, the four vasculatures may need to be extracted, removed, and 3D reconstructed separately. Such objectives can be achieved by the following two protocols.

Firstly, the four pipelines are injected with 10% vermilion powder. Though perfused satisfactorily, the pipelines are incapable of being identified, extracted, and 3D reconstructed because they possess the same CT value on CT images and the thin hepatic artery and bile duct system. The entirety of the portal and hepatic veins within the hepatic lobes and segments can be displayed during 3D reconstruction when the perfusion of the portal vein and hepatic vein is satisfactory, and thin-slice CT images are clear. Secondly, four pipelines are injected with different concentrations of vermilion powder. Because of the concentra-

8 Fig. 1.10  Perfusion of the gallbladder, biliary tract, and hepatic artery. (a) Anterior view, (b) posterior view. Note: Green for the gallbladder, biliary tract, and hepatic duct; red for the hepatic artery

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a

Hepatic artery Hepatic artery

Biliary system

Gallbladder

b Biliary system Hepatic artery

Gallbladder

tion differences, CT showed different CT values during scanning. According to the differences, the four pipelines are 3D reconstructed. Note, at the first perfusion bile should be squeezed out through the common bile duct, since the hepatic artery and bile duct system are relatively small in diameter. The bile duct system may not be adequately perfused at one time, and in that case, reperfusion is needed on the post-­ perfusion day 2 or 3. Anticorrosion and fixation are vital. The natural shape of the liver should be maintained to avoid deformation under pressure, lest distortion of the mold during casting occurs. The portal vein and inferior vena cava are relatively thick and even more so in fresh specimens. In the casting process of large vessels, it is better for the vessels to be thick and sparse, rather than to be thin and dense. To reduce the blood vessel elasticity, traditional anticorrosive methods should be utilized for vascular fixation. During the anticorrosive process, attention must be paid upon leakage of perfusate from vasculature surrounding the liver. In the event of such leakage, blood vessels can be ligated using hemostatic forceps or wire sutures. Since the portal vein and inferior vena cava are relatively thick, the filling agent must be strong and non-brittle to support the weight of the liver. The effect of using the rapid repair powder and liquid for acrylic denture as filling agents is rather satisfactory. The model of the human body, diaphragm, and abdominal cavity is con-

structed out of fiberglass. Then, the liver is placed in the abdominal cavity, in an anatomical position similar to that of the human liver and examined with a thin layer CT scan and MRI, which can display clear intrahepatic vascular structures and achieve strong stereoscopic effects.

1.3.2 Data Acquisition 1.3.2.1 Collection and Dissection of Biliary Specimens Cadaver specimens were obtained from the Institute of Clinical Anatomy of Southern Medical University. The ligamentum teres hepatis, falciform ligaments, left and right triangular ligaments were resected, and the liver was mobilized. The hepatic artery, portal vein, and common bile duct were severed horizontally at the duodenal bulb, and the inferior vena cava was severed above the level of the right renal vein. The vena caval foramen of the diaphragm was opened, the superior and inferior vena cava severed, and the liver procured intact. Then, the liver was perfused through the portal vein with saline or tap water until the color of the liver changed or partially whitened. The broken end of the infrahepatic vena cava was sutured continuously. Small diameter cannulae were inserted in the hepatic artery and common

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bile duct and ligated with sutures. Large diameter cannulae were inserted in the portal vein and suprahepatic vena cava and ligated also. To avoid perfusate leakage while perfusing, small blood vessels in the hepatic hilar area were ligated with silk thread.

1.4

1.3.2.2 Bile Duct Perfusion Two perfusates (yellow) of different concentrations of vermillion powder were prepared:

The isolated liver model perfused by four perfusates with respective colors, was embedded with blue gel. Eight brown-­ red markers were placed surrounding the liver as image registration points. The liver was stored in a freezer for 3 weeks at a temperature of −25 °C and subsequently transferred to the laboratory at −27  °C.  The liver was then serially sectioned at 0.2 mm intervals with the JX1500A vertical milling machine. The serial cross-sections were photographed using a high-resolution digital camera to produce anatomical images, which were uploaded to a computer.

• 10% vermilion powder, perchloroethylene, and yellow oil paint • 5% vermilion powder, perchloroethylene, and yellow oil paint

1.3.2.3 Hepatic Artery Perfusion Two perfusates of different concentrations were prepared: • Red perfusate: 10% vermilion powder, perchloroethylene, ethyl acetate, and red oil paint. • Dark red perfusate: 20% vermilion powder, perchloroethylene, ethyl acetate, and red oil paint.

1.3.2.4 Specimen Perfusion Fixation The specimen, which was perfused through the hepatic artery and bile duct were submerged in gauze saturated with water, and a 10% formalin solution was infused through the portal vein. The portal vein and inferior vena cava were clamped once formalin started to flow out through inferior vena cava. 1.3.2.5 Perfusion and Fixation of the Portal Vein, Inferior Vena Cava, and Hepatic Vein Perfusion and Fixation of the Portal Vein Two perfusates of different concentrations were prepared: • Brown perfusate: 60 g of rapid repair powder for acrylic denture, 60 ml of rapid repair liquid for acrylic denture, 12 g of 10% vermilion powder, 15 ml of dibutyl phthalate, and brown oil paint. • Yellow perfusate: Yellow oil paint and the other components were the same as above. Perfusion and Fixation of the Inferior Vena Cava/ Hepatic Vein Two perfusates of different concentrations were prepared: • Blue perfusate: 60  g of rapid repair powder for acrylic denture, 60 ml of rapid repair liquid for acrylic denture, 12 g of 10% vermilion powder, 15 ml of dibutyl phthalate, and brown oil paint. • Light red perfusate: White oil paint, 12 g of 8% vermilion powder, and the other components were the same as the above.

 igitalized Biliary Tract and Blood D Vessels

1.4.1 L  iver Dissection after Biliary Tract Perfusion

1.4.2 A  cquisition and Analysis of Sectioned Images Cross-sectional pipelines were well displayed, and all pipelines were clear. The inferior vena cava and hepatic vein system were black, and the portal vein system was orange. The hepatic artery, which runs alongside the portal vein was red. The hepatic duct and the gallbladder were dark green. The peripheral hepatic vein and portal vein were clear. Intervals of the anatomical images were 0.2 mm, and 910 pairs of cross-sectional images were acquired. The data file of each section occupies 17.5  MB, and the file size of the liver dataset was 15.3 GB in total (Fig. 1.11).

1.4.3 3D Reconstruction of Images Three-dimensional reconstruction of the cross-sectional images obtained through milling was achieved after registration and segmentation. These images were converted into BMP format to facilitate the subsequent processing (Fig. 1.12).

1.4.3.1 Image Registration After Bile Duct Perfusion Image registration was conducted by external point force combined with moment-to-force. The landmarks pre-­ embedded surrounding the liver were set as registration points. The image registration was performed based on the relatively fixed positions between the liver and those landmarks. The specific methods are: • In the source image, the registration points were displayed on a blue background presenting as dark red point set scattered around the image. These point sets were identified according to the color and their position features.

10 Fig. 1.11 Cross-sectional images of the hepatic hilum

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a Right hepatic vein

Right portal vein

Right hepatic duct

Right hepatic artery

Common bile duct

Hepatic artery

Portal vein

Left hepatic vein

Gallbladder

Hepatic artery

Common hepatic duct

Right portal vein

b

Hepatic vein

Common hepatic duct

Common bile duct Right hepatic duct

Portal vein

Gallbladder

Right hepatic artery

c

Hepatic vein

Right portal vein

Common bile duct

Hepatic artery

Portal vein

Gallbladder

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Fig. 1.12  The display window and 3D reconstructed liver

Fig. 1.13  Image registration of the sectioned images after intrahepatic pipe perfusion (the white arrow points to the registration point) Hepatic artery

• After a comparison of the source and target images, translation and scaling of each image should be performed so that each point of one image can be mapped to a corresponding point of another image. • The area containing the liver was sheared from the source image (Fig. 1.13).

1.4.3.2 Image Segmentation After Bile Duct Perfusion Image segmentation is the process of partitioning an image into multiple meaningful segments according to certain principles. Segmentation of milled images is the extraction of tissues from the liver. The image data of liver parenchyma, hepatic veins and inferior vena cava, portal veins, hepatic artery and gallbladder, and hepatic artery were respectively segmented, and their contour line was extracted.

Hepatic artery

1.4.3.3 3D Reconstruction of the Biliary Tract • Three-dimensional surface rendering reconstructions were generated from image sequences using the Visualization Tool Kit (VTK). Specific methods were: contour lines were extracted into several of these tissue types on every image; the region between contour lines of adjacent images were filled with flat triangles, which formed a banded ring; the 3D surface of the object was generated from a set of contour lines. • The reconstructed liver model was displayed using the surface description method. The model contains five parts, including the liver, the hepatic vein and inferior vena cava, the portal vein, the hepatic ducts and gallbladder, and the hepatic artery. Also, a Windows PC-based 3D visualization demonstration system and Windows operation system of liver were developed. By clicking on

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the corresponding function icons of the display window, transparency (a value of 0 means completely transparent, a value of 1 means completely opaque, and values between 0 and 1 are semitransparent) and color of each part can be adjusted, and thus the liver can be displayed Fig. 1.14  A 3D reconstructed model of the liver and its internal structure. (a) Structure of the liver and its internal pipelines (liver translucent, other opaque); (b) Structure of the liver and its internal pipelines (Back view) (semitransparent liver, transparent liver veins)

and observed as needed. The liver model can be rotated by holding down the left mouse button and dragging laterally. The viewer can zoom in or out of the image by right clicking the mouse and dragging up or down (Fig. 1.14).

a

b

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Data for 3D reconstruction of the intrahepatic vessels were mostly obtained from CT, MRI, and ultrasound; however, information collected by these instruments was incomplete or insufficient. Using these data for 3D reconstruction of the liver would lead to inevitable defects (Spitzer and Whitlock 1998). However, after perfusion and casting of intrahepatic vessels applying the advanced casting technology, an image dataset of the liver section could be obtained through a serial section of the liver at 0.2 mm intervals with a milling machine. These images contained detailed information of intrahepatic vessels. The image sequences were registered, segmented, and subsequently reconstructed using the VTK (William et  al. 2000). After registration and segmentation of these images, VTK was used to establish three-­ dimensional surface morphological models of hepatic veins and inferior vena cava, hepatic artery, portal vein, bile duct, and gallbladder, respectively. By setting the color and transparency of each pipe structure and zooming-in, zooming-­ out, and rotating the model, it is possible to accurately and comprehensively observe and study the morphology and adjacent relationship of the liver and its various structures, which provides an excellent technical platform for teaching and further researching the anatomy of the intrahepatic biliary tract.

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References Couinaud C. Surgical anatomy of the liver revisited Ch4. Anatomy of the dorsal sector of the liver. New considerations on liver anatomy. Paris: Pers ED; 1989. p. 26–39. Fang C, Yang J, Fan Y, et  al. The research of virtual hepatectomy. Chinese J Surg. 2007;45(11):753–5. Hjortsj CH. The topography of the intrahepatic duct system. Acta Anat (Basel). 1951;11:599–615. Kogure K, Kuwano H, Fujimaki N, et al. Relation among portal segmentation, proper hepatic vein, and external notch of the caudate lobe in the human liver. Ann Surg. 2000;231(2):223–8. Misra SP, Dwivedi M.  Pancreaticobiliary ductal union. Gut. 1990;31:1144–9. Ramesh Babu CS, Sharma M. Biliary tract anatomy and its relationship with venous drainage. J Clin Exp Hepatol. 2014;4(Suppl 1):S18–26. Spitzer VM, Whitlock DG. The visible human Dataset: the anatomical platform for human simulation. Anat Rec. 1998;253(2):49–57. Spitzer VM, AcKerman MJ, Scherzinger AL, et  al. The visible human male: a technical report. J Am Med Inform Assoc. 1996;3(2):118–30. Wigmore SJ, Redhead DN, Yan XJ, et al. Virtual hepatic resection using three-dimensional reconstruction of helical computed tomography angioportograms. Ann Surg. 2001;233(2):221–6. William JS, Kenneth MM, Lisa SA, et  al. The VTK user’s guide. New York: Kitware; 2000. Zhong S.  Applied clinical anatomy[M]. Beijing: People’s Military Medical Press; 1998. p. 355–6.

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Application of Multi-slice Spiral CT and MRI in Biliary Surgery Suisheng Zheng, Xijun Gong, Xuchang Zhang, Yangguang Yuan, Xinming Li, and Chihua Fang

2.1

Introduction

Multi-slice computed tomography (CT) and Magnetic Resonance Imaging (MRI) each offers unique methods of viewing internal structures, diseased tissue, and deposits such as calculi. This chapter will present: • • • • • •

Basic principles of Multi-slice CT Patient preparation and scanning modalities Clinical application to biliary system investigations Basic principle of MRI MRI patient preparation and scanning modalities MRI in biliary surgery

2.2

 pplication of Multi-slice Spiral CT A in Biliary Surgery

2.2.1 Basic Principles Computed tomography (CT) scan is an imaging technology that uses a series of X-rays to build cross-sectional images of the body. The emitter of X-rays rapidly rotates around the patient, and the detector in the scanner picks up the images of a body section and measures the differences between the X-rays that are absorbed by and transmitted through the body, which is called attenuation. Different tissues each have a different attenuation coefficient. The signal transmitted by the detector is in analog form, and it must be subsequently converted into digital form by an analog/digital converter before it can be sent to a PC for processing. These digital

signals are the sum of the attenuation coefficients. Digital 3D images are divided into small equal-sized polygons, and the polygons in three-dimensional space are called voxels (Fig. 2.1). The X-ray attenuation or absorption coefficient is obtained and then arranged into a matrix, which is called the digital matrix. The value of each digit in the matrix is converted into different gray levels. They are subsequently converted into pixels. Thus, a grayscale CT image is generated (Miller et al. 2014). Multi-slice spiral CT (MSCT) is the further development of single-slice spiral CT based on slip-ring technology. The slip-ring mechanism involves electric slip-ring devices composed of two parts, a stator, and two concentric rotors. The slip ring is installed in the stationary part, while the fixed brush in the rotatable part. The fixed brush makes sliding contact with the conductor ring, and the X-ray tube is energized through the brush and slip-ring by the power supply system. Therefore, the X-ray tube can rotate continuously at high speed during data acquisition. The path of a full cone X-ray emitted from the tube of MSCT presents a helical trajectory relative to the patient. During the acquisition of volume CT data, the patient is continuously moved through the gantry as the X-ray tube rotates Since the X-ray tube rotates continuously around the patients with a helical movement, the scanning speed is significantly enhanced. The increase in the scanning speed and width of detector coverage can reduce the scanning time. In the obtained matrix, a threedimensional geometry is formed by the x, y, and z-axes. The obtained information is produced from the volumetric data set within a specific range (Goldman 2008). The reconstructed organ image is three-dimensional and allows for 360° rotation and cross-section observations. Meanwhile, the increase in scanning speed can yield dynamic scanning and observation of organ images.

S. Zheng · X. Gong The Second Affiliated Hospital of Anhui Medical University, Anhui, China X. Zhang · Y. Yuan · X. Li · C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_2

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Fig. 2.1  Voxel, pixel, and digital matrix

2.2.2 T  echniques and Clinical Applications of MSCT for Biliary Imaging 2.2.2.1 Methods Preparation Patients are instructed to fast for 4–8 h before CT examination. In order to avoid high-density artifact interference, CT should not be performed within 72  h of a barium meal. Abdominal fluoroscopy should be performed before examination. Barium sulfate or drugs that affect the absorption of X-rays should be drained as much as possible if they are found remaining in the colon. Thirty minutes before the examination, 500–800  ml of a 1.5%–3.0% iodinated contrast agent or water should be administered orally; an additional 400  ml of contrast agent should be administered immediately before the examination. Positioning the patient in the right lateral decubitus position for 5 min is sometimes necessary to fill the duodenum and the proximal small intestine, which is beneficial to show the relationship of the duodenum to the head of the pancreas and the lower end of the common bile duct. When choledocholithiasis is suspected, water shall be taken instead of a contrast agent, so as not to confuse gallstones with contrast agent in the duodenal diverticulum. If the focus of observation is the lower common bile duct and ampulla, an anticholinergic drug such as anisodamine-2 (654–2) can be administered intramuscularly 15  min prior to the scan to

achieve low tension of gastrointestinal tract, full dilation of the duodenum, and reduction of peristalsis artifacts. In such cases, the anatomical structure of the lower common bile duct and ampulla can be better displayed, and so can the lesions. It is critical to instruct patients to hold their breath under the condition of calm breathing before the examination and to remove foreign objects that affect X-ray attenuation at the site of the examination. These steps are essential for precise diagnoses. Selection of Scanning Parameters The selection of scanning parameters includes three aspects: collimator width, pitch, and reconstruction interval. Collimation width determines the slice thickness of the scan layer, most of which are set as 3–5  m. Pitch refers to the distance that the patient travels through the CT scanner per 360° rotation of the X-ray tube, divided by the beam collimation width. Alternatively, the pitch can be replaced by table speed. Meanwhile, collimation width determines the thickness of the reconstruction slice. Narrowing the collimation width can reduce the photon density of the layer and improve the resolution, but it is challenging to cover the full scanning range. The scanning range can be enlarged by increasing the collimation width though this will reduce the special resolution. The spatial resolution of the post-­ processed image is determined by the reconstruction interval, and most of the recombination intervals of images should be less than 1 mm.

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

Scanning Modalities Axial Plain Scanning  Axial plain scanning of the biliary system is performed as part of a routine clinical examination. The patient should be in a supine position, and the scan range extends from the top of the diaphragm to the lower edge of the liver. The patient breathes calmly and holds the breath while exposed. Continuous scan with a thickness of 5 mm and a thin-slice scan of the region of interest (ROI) in small lesions should be performed. The scan range usually includes the entire liver, and the range of biliary system ranges from the top of the liver to the uncinate process of the pancreatic head. The range should be adjusted according to the patient’s clinical status. When thickening of the gallbladder and bile duct wall or an intraluminal soft tissue mass are detected, a contrast-enhanced CT scan is necessary. It enhances the contrast between the bile duct and the surrounding tissues and clearly shows the stereoscopic anatomy of the biliary system, which is convenient for evaluating causes of biliary obstruction and the degree of tumor invasion.

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and differential diagnosis of lesions. Contrast-enhanced scanning not only provides qualitative information through the degree of enhancement of diseased tissue, but also clearly shows the blood vessels at the porta hepatis, which helps evaluate the nature of biliary lesions in this area. For malignant lesions, the resection rate can be determined according to vascular involvement. At the same time, the liver parenchyma is significantly enhanced during the portal venous phase, which is beneficial for the detection of intrahepatic bile duct neoplastic lesions, biliary tract tumors, and hepatic metastases.

Contrast-Enhanced Examination • Typically, the water-soluble iodinated contrast agent is administered by rapid bolus intravenous injection. The usual dose for bolus injection is 1.0–2.0  ml/kg at an injection rate of 3 ml/s. Triple-phase scanning is generally adopted: the timing of the delay is synchronized with the start of injection. The arterial phase scan is triggered by the threshold triggering protocol or starts at a delay of Contrast-Enhanced Scanning 20–30 s. The portal venous and equilibrium phases start at Principles and Significance of Contrast-Enhanced a delay of 60–70 s and 2–3 min, respectively. Observation CT  Enhanced scanning can better display the iso-dense of the extrahepatic bile duct should start from the lesions, observe the blood supply of the lesions, and identify bifurcation of the left and right hepatic ducts, the the nature of the lesions. Principles of contrast agents: Water-­ pancreatic head, to the continuous thin layer of third and soluble iodinated contrast agent that is intravenously adminfourth segments of the duodenum. istered weakly or rarely binds to the human protein, and • Dynamic Enhanced Scanning After the bolus injection of instead, it is distributed in large quantities in the blood vescontrast agents, the lesions or the whole biliary system are sels, then flowing into the extracellular fluid of various tisscanned continuously at different times to observe the sues and gradually reaching equilibrium. The enhancement time–density curve of lesion enhancement. The dynamic of normal and diseased tissues is caused by the increase in enhanced scan can obtain more information on the blood the amount of iodine, increasing local density. The amount supply of the lesions, compared with conventional triple-­ of contrast agent distributed in a specific tissue depends on phase scanning, which is of great significance for the volume and velocity of blood flow, microvascular permedifferential diagnosis. ability, and the volume of the extracellular fluid of this tissue. • CT Angiography CT angiography is an examination that The effect of enhancement is related to the concentration and displays biliary lesions, especially the condition of the injection method of the contrast agents; it is also associated arterial blood supply of rich vascularized lesions and with whether the scanning time is synchronized with the adjacent portal veins. It should be performed by multi-­ time to peak enhancement in the tissue. slice CT, and fast bolus injection should be adopted. The Enhanced scanning plays a significant role in diagnostic thickness of the reconstruction slice should be below techniques. The fundamental purpose of using contrast 1.0  mm. After the acquisition of images at enhanced agents is to enhance the contrast between the intrahepatic arterial and venous phases; image post-processing and extrahepatic biliary lesions and normal tissues through software should be used to display the relationship contrast enhancement, thus achieving a clear display of between specific arterial or venous vessels as well as lesions. Some lesions are not clearly displayed or show an blood vessels and their surrounding tissues and lesions. ambiguous boundary on the plain scan. Rich vascularized lesions can be displayed after enhancement; poorly 2.2.2.2 Post-Processing Techniques for MSCT vascularized lesions exhibit poor enhancement, while Volume data can be processed by a variety of post-processadjacent normal tissues are enhanced; thus, increasing the ing techniques, including image editing and three-dimendetection rate. The application of contrast-enhancing agents sional (3D) processing. There are four methods for the plays an essential role in the localization, qualitative analysis, reconstruction of spiral CT:

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Shaded Surface Display Shaded Surface Display (SSD) is a process of surface-­ rendering and reconstruction that connects all pixels with a given value higher than a certain threshold to form a surface model. The first step is the calculation of the normalized CT value at the surface points for 3D surface reconstruction. Pixels above the threshold are assigned to the iso-density, while the pixels below this threshold are discarded. Through computer processing, the pixels above the threshold are reconstructed into an independent three-dimensional structural model. This method is of great value in displaying the whole lesion, and its advantage is that the image has a strong stereoscopic effect, which accords with human visual cognition. The disadvantage is that the selection of the threshold has an essential influence on the recombination effect, and the display of the smaller bile duct is easily affected by the partial volume effect. Maximum Intensity Projection Maximum Intensity Projection (MIP) is a volume rendering technique that generates 2D images from volumetric data along with the mathematical rays. It encodes and recombines the highest density value encountered along the viewing ray. This technique is mostly used in the recombination of the biliary system after enhancement, with the advantages of displaying biliary system structure in multiple directions and angles, and relatively easy operation. However, the limitation of this technique includes the inability to show superimposed objects, which can be addressed by segmentation techniques. Multi-Planar Reconstruction and Curved Planar Reformation Multi-planar Reconstruction (MRP) involves the process reformatting of a 3D data set acquired from volume scanning into a three-dimensional reconstruction of sagittal, coronal, and oblique anatomical planes. Curved Planar Reformation (CPR) involves generating 2D images that are reconstructed in arbitrary planes from axial image data. Both of these methods produce two-dimensional images, which are not conducive to displaying the overall anatomical structure. Nevertheless, they are fast and straightforward, and CPR can completely display the structure of the biliary tree. Volume Rendering A Volume Rendering (VR) process involves calculating the percentage of substances in each pixel by a computer system and displaying them as grayscales. Different brightness levels are assigned accordingly, and the contrast between tissues can be adjusted as needed. VR is one of the most commonly used methods for the vascular reconstruction of the porta hepatis. It cannot only display anatomical structures with different tissue density, but the structure of the lumen and its relationship with surrounding structures (Flohr and Ohnesorge 2007).

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2.2.3 Application of CT to the Biliary System 2.2.3.1 For Bile Duct Stones and Biliary Tract Inflammation CT scanning has the advantages of high speed, rapid imaging, small artifacts, and high resolution. Some patients with bile duct stones have an acute onset, which can be diagnosed accurately and timely by the CT examination. CT can also detect the location of bile duct stones and associated biliary dilatation and inflammatory lesions. Thus, it is widely used in clinical practice. Because of its nature, it has a high diagnosis rate for high-density stones. However, its identification of iso-density or slightly low-density stones is insufficient due to the fact that it is easily affected by partial volume effect, and if dilatation of the common bile duct occurs, misdiagnosis can easily happen. Also, its clinical use is limited due to its low sensitivity to the diagnosis of silt-like and iso-density stones. CT examination can show the distribution of intrahepatic bile duct stones and the dilatation of the duct system; meanwhile, it can evaluate the atrophy of hepatic parenchyma or associated tumor, the presence or absence of hypertrophy in the liver lobe, splenomegaly caused by secondary cholestatic cirrhosis and portal hypertension, and esophageal varices. However, CT scans create two-dimensional cross-sectional images, incapable of further revealing the relationship between hepatolithiasis, bile duct stenosis, and adjacent tissue structures, especially for silt-like stones and negative stones, reconstruction and careful selection should be performed based on the original thin-slice data. For biliary inflammatory lesions and liver lesions complicated by gallstones, abnormal enhancement of the bile duct wall and liver parenchyma can be found by plain and contrast-enhanced CT scans. For diagnosis and differential diagnosis of congenital lesions such as biliary tract variations, contrast-enhanced CT scans can be significant on the premise that enhancement of liver parenchymal phase can be accurately grasped, in combination with three-dimensional reconstruction of the biliary tract. 2.2.3.2 For Diagnosis of Tumor and Biliary Obstruction With the advancement of CT technology, MSCT scans in a wide range. The application of MPR and CPR for cholangiopancreatography can clearly show the cholangiopancreatic structure and anatomical relationship between the lesion and surrounding tissues. It can also identify the cause of obstruction, improve the diagnosis rate of biliary obstruction, and provide more imaging evidence for the diagnosis of biliary obstruction in the aspects of location, course of disease development, and complications. It provides strong technical support for the clinical selection of appropriate treatment. MSCT is a mature and commonly used imaging method for clinical diagnosis of hilar cholangiocarcinoma. By using this tech-

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

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nique, the extent of the dilatation of proximal bile duct and the location of biliary obstruction are displayed; meanwhile, it reveals the shape and thickness of the bile duct wall, as well as the size and boundary of the tumor; it also indicates whether there is abdominal metastasis. Also, compared with ultrasound, this method is not affected by factors such as intestinal gas, obesity, and examiners. In this way, the accuracy of an examination is improved. The advantage of MSCT lies in its powerful post-processing function, such as MPR or CPR technique, which can improve the image resolution and clearly show the location of lesions and condition of the biliary tract.

2.2.3.3 For Display of the Blood Supply of the Biliary System The intrahepatic bile duct and common bile duct have a copious blood supply after entering the pancreatic parenchyma and duodenal wall. Slender arteries have less surgical significance. Therefore, the biliary vessels refer to the arterioles supplying the extrahepatic and pancreatic bile ducts. The cystic artery typically originates from the right hepatic artery within the Calot’s triangle. When approaching the gallbladder, the cystic artery bifurcates into anterior and posterior branches at the neck of the gallbladder. Variations in cystic artery anatomy are mainly manifested in three aspects: number, origin, and course. Besides the normal trunk type, double trunk or nonclassical branch types may also appear. The cystic artery typically originates from the right hepatic artery, sometimes from the left hepatic artery, the middle hepatic artery, the hepatic artery proper, the gastroduodenal artery, or the superior mesenteric artery. The cystic artery may also arise from the front of or behind the common hepatic and bile ducts, and it may pass down below the cystic duct. Variations in the right hepatic artery are common, so cystic arteries originating from differing hepatic arteries will have a concomitant structure. The blood supply of the common bile duct is copious and complex, and the blood supplying arterioles are thin. The extrahepatic bile ducts are roughly divided into the upper and lower portions (Fig. 2.2). The upper part of the bile duct involves the common bile duct above the upper edge of the duodenum and the lower part of the common hepatic duct. The lower part of the bile duct includes the upper edge of the duodenum to the upper edge of the pancreatic head, including the retroduodenal part of the common bile duct and the pancreatic part of the common bile duct, which has not yet entered the pancreatic parenchyma. CT observation of extrahepatic and pancreatic bile duct rarely showed any variation, and there is no specific route or confluence. There were also few gross vascular features such as the right hepatic artery arising from the gastroduodenal artery (Fig. 2.3) and the right hepatic artery/common hepatic artery from the superior mesenteric artery (Fig. 2.4).

Fig. 2.2  Structure of the common bile duct

Fig. 2.3  The right hepatic artery arising from the gastroduodenal artery

Blood Supply to the Lower Part of the Common Bile Duct The blood supply to the lower part of the common bile duct can be divided into 3 types according to the origin of arterioles: • Type I Supplied by the superior pancreaticoduodenal arteries. According to their arterial arch anastomosis, this type is divided into two subtypes: type Ia and Ib. In type Ia, there are no visible anastomotic arcades between the

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Fig. 2.4  The right hepatic artery (RHA)/common hepatic artery from the superior mesenteric artery (SMA)

superior pancreaticoduodenal arteries and inferior small arteries, while in type Ib arterial arcades are formed. • Type II Supplied by other arterioles. • Type III No definitive supply of arterioles. Type I is common, accounting for approximately 85%. The superior pancreaticoduodenal artery travels in a relatively fixed direction. It usually arises after branching off from the gastroduodenal artery, hooks around the common bile duct, and goes toward the lower right. Type Ia is relatively common, mainly accompanying the lower part of the common bile duct (Fig. 2.5a–c). Type I b is relatively rare. It can be observed that the superior pancreaticoduodenal artery and inferior pancreaticoduodenal artery are anastomosed into a small arterial arch. It accompanies the lower part of the common bile duct and the head of the pancreas (Fig. 2.6). Type II (Fig. 2.7) and type III (Fig. 2.8).

Blood Supply to the Upper Part of the Common Bile Duct The enhancement rate of arterioles supplying the upper part of the common bile duct is not high. Half of them are not displayed, and among those that are, about half is in the proximal portion of the cystic artery (Fig. 2.9), and the other half originates from the right hepatic artery (Fig. 2.10). Very few blood supply arterioles arise from the hepatic artery proper (Fig. 2.11), common hepatic artery (Fig. 2.12), or left hepatic artery (Fig. 2.13). The upper part of the bile duct is mainly supplied by the branches of the cystic artery and hepatic artery proper, and cases displaying the arteriole trunk are rare. The lower part of the bile duct is mostly supplied by the superior pancreaticoduodenal artery; with a relatively high enhancement rate and fixed course, the superior pancreaticoduodenal artery appears to be the primary arterial supply for the bile duct. The surgeon should be vigilant when a variation of the right

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

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b

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Fig. 2.5  (a–c) The superior pancreaticoduodenal artery accompanying the lower part if the common bile duct Fig. 2.6  The superior pancreaticoduodenal artery and the inferior pancreaticoduodenal artery are anastomosed into a small arterial arch

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b

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Fig. 2.7 (a–c) Type II. RGEA right gastroepiploic artery, RHA right hepatic artery, LHA left hepatic artery, PHA proper hepatic artery, SMA superior mesenteric artery, CBD common bile duct

hepatic artery/common hepatic artery from the superior mesenteric artery is encountered during surgery. In the case of insufficient exposure in the surgical field, such as accident injury of the right hepatic artery or common hepatic artery, severe consequences of hepatic ischemia would occur. If a preoperative CTA examination can be performed, the postprocessing image can better help the surgeon to perform surgery. The incidence rate of the superior pancreaticoduodenal artery supplying the lower part of the common bile duct is relatively high, and type I accounts for the majority. The superior pancreaticoduodenal artery is thick and has a stable

course, which indicates that it provides a plentiful blood supply. Thus, this vascular pathway should be avoided when choosing surgical areas. The incidence rate of type Ib is not high. The anastomosis between the superior pancreaticoduodenal artery and the inferior pancreaticoduodenal artery is very rare. However, if a small arterial arcade can be anastomosed, any part of the lower bile duct could be severed, which would not cause complications such as postoperative biliary ischemia. However, this arterial arcade is usually too thin, which requires special care to avoid injury. The incidence rate of the proximal segment of the cystic artery sup-

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery Fig. 2.8  Type III

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Fig. 2.9 (a–c) The proximal part of the cystic artery supplying the upper part of the common bile duct

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Fig. 2.10  Branches of the right hepatic artery supplying the upper part of the common bile duct Fig. 2.12  Branches of the common hepatic artery supplying the upper part of the common bile duct

Fig. 2.11  Branches of the hepatic artery proper supplying the upper part of the common bile duct

plying the upper part of the common bile duct is relatively high. The initial segment of the cystic artery often accompanies the upper part of the common bile duct, and the journey is often short. The operation of independent cholecystectomy or common bile duct surgery has little impact. When ligating the cystic artery and transecting the upper part of the common bile duct simultaneously, small blood supplying arteries should be protected to avoid damage to the very fragile arterioles trunk; when the cystic artery originates from the gastroduodenal artery, the course of its accompanying upper common bile duct is relatively long. In the cholecystectomy,

Fig. 2.13  Branches of the left hepatic artery supplying the upper part of the common bile duct

the proximal segment of the cystic artery should be preserved. MSCTA does not show the problem of blood supply to the posterior portal artery mentioned in many literatures, which is probably because the vessels are too thin or there is no surgical confirmation. In a nutshell, the arteries supplying the upper part of the common hepatic duct/common bile duct are thin, with an unpredictable shape. Therefore, it is inadvisable to separate and ligate small vessels in this area blindly.

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

At present, the biliary tract imaging technique of the 3D Visual System (3DVS) has been applied to clinical practice; however, successful acquisition of high-quality submillimeter CT data is the key to processing high-quality 3D images. In terms of scanning methods, it is vital to accurately grasp the scanning time of the arterial phase, portal venous phase, and equilibrium phase. The use of the bolus-triggering technique is recommended; besides, doses of contrast agent should be strictly calculated based on the patient’s weight. The above two aspects are critical factors for enhanced scanning to obtain high-quality thin-section data. In particular, since there are individualized differences in the pathological changes of patients with tumors in the lower part of the common bile duct and periampullary carcinoma, CT data directly affects the quality of the model reconstructed by MI-3DVS. Nothing but strict and standardized examination can provide accurate and high-quality CT data for the processing of digital medical software conducive to surgical planning, surgical risk assessment, surgical procedure demonstration, and clinical teaching.

2.3

Application of MRI Technique in Biliary Surgery

2.3.1 Basic Principles of MRI When X-rays and CT penetrates through the human body, the density difference caused by attenuation coefficients of various tissues is formed. In adjacent organs or tissues with similar density, a sharp contrast image cannot be formed. MRI is a medical imaging process that uses different chemical information emitted by tissues. The MR image displays not only morphological but also functional changes of tissues and organs, thus providing biochemical information and dynamic quantitative data. Modern Medicine has put forward higher requirements for Imaging, and its goal claims to be comprehensive, rapid, accurate, and non-invasive. Imaging is playing an increasingly important role in modern medicine, and thus MRI shows distinct advantages for the diagnosis of diseases. As an integrated part of medical imaging, MRI has developed rapidly in recent years. Its development represents a huge milestone for the medical imaging world. The modality of MRI is continually advancing from morphologic to functional diagnosis, and from static imagebased to continuous film image or dynamic image-based diagnosis, while morphologic diagnosis remains an essential component in clinical MRI.

2.3.1.1 MRI Devices The major components of a medical MRI scanner include the main magnet, gradient system, radiofrequency system, computer systems, and other auxiliary equipment.

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The Magnet The main magnet produces an intense and stable magnetic field. Currently, the most widely used type is the superconducting magnet. The superconductive coil constructed with nickel–titanium alloy is immersed in liquid helium in a favorable low-temperature environment. The wire has no electric resistance in its superconducting state and therefore can create intense magnetic fields through the closed coil. Compared with permanent magnet type and normally conductive type, the superconductive type has the advantages of producing high-intensity and high-stability magnetic fields. The intensity of a magnetic field measured in Tesla (T), is a major measurement of magnetic field strength. The earth’s magnitude of geomagnetic intensity at the north and south poles is roughly 0.7 gauss (G). The conversion relationship between Tesla and Gauss is 1 T = 10,000 G. The magnetic field strengths of the permanent magnet type and the normally conductive type are mostly less than 0.5  T, and the superconducting magnet mostly ranges from 1.0  T to 3.0 T. Besides, MRI demands a high degree of homogeneity of the main magnetic field because the magnetic field homogeneity is critical for spatial positioning of the MRI signal, improving signal-to-noise ratio and reducing image artifacts (Andrew 2016). The Gradient System The gradient system consists of gradient amplifiers and three sets of gradient coils in the X, Y, and Z directions. The primary function of gradients is to modify the main magnetic field and generate a gradient magnetic field for spatial encoding of the MRI signal. The key parameters to determine the gradient of the magnetic field are intensity and slew rates. Gradient strength refers to the difference in magnetic field strength per unit of distance. The typical units are expressed in millitesla per meter (mT/m). Images with a smaller number of pixels and higher spatial resolution are sharper and require a higher magnetic field gradient. Slew rates of the gradient magnetic field refer to changes in the gradient field strength in unit time and unit distance. The typical units are expressed in mT/m/ms. High slew rate and high gradient field strength help to shorten echo times, speed up signal acquisition, and increase image signal-tonoise ratio. The Radiofrequency System The radiofrequency (RF) system consists of an RF transmitter, an RF amplifier, and RF coils. The transmitter emits radiofrequency pulses in the form of electromagnetic radiation, permitting exciting low energy protons to transition to higher energy levels, and causing phase synchronization of the protons (The protons do not run parallel to the magnetic field lines, but rather undergo a rotating motion, which is called precession).

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Radiofrequency Coils Radiofrequency (RF) coils are essential components of an MRI scanner and the key element for imaging. The performance of transmit coils is related to data acquisition of MRI, and the basic goal of receive coils is to achieve the highest signal-to-noise ratio (SNR). The development of phased array coils is considered a milestone in RF coil technology. Phased array coils consist of several smaller coils that are grouped together into a coil unit, and it requires multiple data acquisition channels to match with it. Phased array coils have the following advantages: large region of sensitivity and high SNR; enhanced image quality in thin-­slice scanning, high spatial resolution scanning and low field strength machine MRI; improved signal acquisition speed; small coils can be used individually or simultaneously (Grover et al. 2015). The Computer System The computer system controls all the work of the MRI scanner, including RF pulse excitation, signal acquisition, data operation, image recombination, and processing. MRI scanner upgrade is closely related to the development of computer science. The rapid development of contemporary computer technology enables a huge leap forward in upgrading of the MRI software, with new possibilities to expand the use of MRI. Other Auxiliary Equipment MRI auxiliary equipment mainly includes the scanner table, patient-positioning system, operation console, cooling system, air conditioning unit, system for image transmission, film storage and processing, and physiological monitoring equipment.

2.3.1.2 Basic Principles of MRI • The study object of MRI is the proton. The atom comprises a central nucleus and orbiting electrons. The nucleus contains positively charged protons. Protons precess around the axis, similar to the way planet earth moves around the sun. This interaction with the proton’s magnetic field creates magnetic resonance. Normally, the direction of the magnetic field produced by protons in the body is random. • When the patient is placed inside a large magnet, the protons’ axes in the body all lineup. Protons in the body align with the main magnetic field. Slightly more than half the protons are aligned with and the rest are aligned opposite the direction of the magnetic field, and thus creating a net longitudinal magnetization vector. • A radiofrequency pulse at the same frequency disrupts the magnetic field direction of protons, and thus creating a net transverse magnetization vector.

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• When the RF pulse is turned off, the excited hydrogen nucleus gradually releases the accumulated energy, and its phase and energy level begin returning to its equilibrium state. This process is called relaxation, just like a tensioned spring will quickly return to its original shape after the external force is removed. Relaxation is the process of releasing energy and producing MRI signals. It consists of two simultaneous and independent processes: longitudinal relaxation and transverse relaxation. Longitudinal relaxation: after the RF pulse is turned off, excited protons spontaneously release energy and fall back from the high to the low energy states under the action of the main magnetic field. The longitudinal magnetization vector gradually increases and recovers to its initial equilibrium. The process is called longitudinal relaxation. The time required for the magnetization to reach 63% of its initial value is called the longitudinal relaxation time, or designated T1 (Fig. 2.14). Transverse relaxation: after the RF pulse is turned off, the synchronization of protons is lost. The protons in the same direction disperse, causing the transverse magnetization vector to decay from maximum to zero, which is called transverse relaxation. The time required for the transverse magnetization to decay from maximum to 37% of the initial magnetization is called the transverse relaxation time, or designated T2 (Fig. 2.15).

100%

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0%

short T2

TE

long T2

time(ms)

Fig. 2.14  The longitudinal relaxation time

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Fig. 2.15  The transverse relaxation time

time(ms)

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

T1 and T2 reflect tissue characteristics, not the absolute value. T1 is the parameter that describes the speed of longitudinal relaxation of tissues. Relaxation speeds vary in different tissues, resulting in different T1 values. Different T1 values of various tissues are the basis on which MRI can distinguish different tissues. The main factors affecting T1 are tissue composition, structure, and magnetic environment, and T1 is also related to the intensity of the external magnetic field. T2 is the parameter that describes the speed of transverse relaxation of tissues. The relaxation speed of different tissues varies, so T2 values of various tissues are different. By use of this principle, normal tissue from pathologic tissue can be differentiated. The main factors affecting T2 are the external magnetic field and the homogeneity of the magnetic field within the tissue (Nitz 2006). • The analog signals are converted into a digital form by computers with an analog-to-digital (A/D) converter, and the digital signal is converted back into an analog form (images) with a digital-to-analog (D/A) converter.

2.3.2 MRI Examination of Biliary Tract System 2.3.2.1 MRI Preparations Patient Preparation • Patients fast at least 6 h prior to MR imaging; if necessary, negative gastrointestinal contrast agent should be administered orally (such as ferric ammonium citrate in an effervescent tablet solution, 100 ml warm water+2 ml of Gd-DTPA solution). • Remove superficial metallic foreign bodies. • Explain the examination procedure and train the patient to hold breath. Coils and Patient Positioning • Coils: Phased-array surface coils for abdominal imaging. • Patient positioning: The patient lies supine on the scanning table and a coil is centered at the midline of the table. The mid-sagittal plane is aligned with the longitudinal center of the coil, and a respiratory gating is placed below the costal margin. Instruct the patient to breathe quietly and regularly. The collection center is aligned with the xiphoid process.

2.3.2.2 Regular Scan Sequences Conventional Cross-Sectional T1W1 and T2W1 Sequences It refers MRI scanning covering the liver, gallbladder, pancreas, and spleen. T1W1 is based on either a gradient echo or a spin echo. If the patient breathes evenly, a respiratory-trig-

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gered fat-suppressed turbo spin-echo T2W1 is preferred; if the patient cannot breathe regularly, but can hold their breath well, the use of single-shot turbo spin-echo T2W1 sequence in combination with fat suppression technology can be adopted. The conventional slice thickness is 5–8 mm, and the slice interval is 20%–30%. Small lesions can be scanned without intervals at a slice thickness of 1–2 mm. Single-Shot Turbo Spin-Echo Coronal Sequences The oblique coronal position parallel to the common bile duct is often used, which can clearly display the relationship between the common bile duct and its surrounding tissue structures. 2D or 3D T2W1 The current protocols often use a two-dimensional single-­ shot fast spin-echo sequence. The common bile duct is found on the horizontal axis image; centered around it, thick slice imaging can be conducted in multiple directions, with a thickness of 30  ~  60  mm. Thin-slice coronal scanning is adopted in 3D imaging, acquired images are reformatted using maximum intensity projection (MIP). Transaxial Single-Shot Turbo Spin-Echo Fat Suppression Sequences On the basis of coronal single-shot turbo spin-echo sequences and MRCP, an axial scan is performed at the obstruction level, using the respiratory triggering technique. The scanning range includes the upper and lower obstruction points. Dynamic Enhancement Sequence A dynamic enhanced scan is required when tumors or tumor-­ like space-occupying lesions cannot be diagnosed. It can improve the lesion detection rate and qualitative accuracy. The principle of contrast-enhanced MRI similar to that of contrast-enhanced CT, is to display contrast enhancement of pathology or anatomical structures (the increased signal intensity). In clinical practice, extracellular contrast agents such as gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) are often used as contrast agents. These agents have paramagnetic effects and are administered intravenously at a dose of 0.1 mmol/ kg and at a flow rate of 3 ml/s. They are used to shorten the T1 and T2 relaxation times (mainly for T1 relaxation time of tissues). T1W1 signal in spin-echo or gradient-echo sequence can be increased. Dynamic contrastenhanced MRI enables repeated imaging in the same breath-holding state following contrast agent bolus administration. The time interval is determined according to the specific situation. Breath-holding scans can eliminate respiratory motion artifacts. In the case that the patient breathes evenly, and time is sufficient, scanning without breath holding combined with respiratory triggering setup is acceptable. Another type of commonly used contrast agent in clinic is hepatobili-

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ary-specific contrast MR agents, such as gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) and gd-benzyloxypropionictetra-­acetate (Gd-BOPTA), which have all the functions of Gd-DTPA and hepatocyte-specific contrast agent. They can reflect both the blood supply and the uptake function of the lesion, thus providing more information for the clinician and improve the confidence of diagnosis. In general, hepatocyte-­specific contrast agents are not taken up by non-hepatocyte-­derived liver lesions, so the liver-tolesion contrast is significantly enhanced after injection of the medium. Thus, more lesions can be found, which is conducive to the formulation of surgical plans. Hepatobiliaryspecific contrast agents can also be used in cholangiography, which can effectively differentiate the lesions inside and outside the bile duct and have obvious advantages in the diagnosis of postoperative bile leakage.

2.3.2.3 Special Scan Sequences of Biliary System Magnetic resonance cholangiopancreatography (MRCP) is the most commonly used and most reliable method in MRI hydrography. MRCP exploits bile as a contrast agent by acquiring the images utilizing heavily T2-weighted sequences combined with fat suppression technology. The stationary fluid-filled structures in the abdomen such as intrahepatic and extrahepatic biliary trees, gallbladder, and pancreatic ducts appear hyperintense, while the surrounding substantial organs and blood vessels containing flowing fluids have low intensity and appear black. The anatomical images of the pancreatic bile duct are subsequently reformatted by maximum intensity projection (Fig. 2.16).

S. Zheng et al.

The requisite condition to obtain a high-quality MRCP image is highlighting the difference in signal intensity between the area of interest and the background. Usually, a long TR (4 times the maximum tissue T1) and long TE sequence can be used, which results in obvious attenuation in the signal of soft tissues in the background. This leads to increase in signal contrast between the background soft tissues and the static fluid, thus enhancing spatial resolution. In clinical practice, MRCP usually has three imaging methods: 3D Volumetric Acquisitions The use of fast spin-echo sequences with long echo train length or single-shot turbo spin-echo sequence in combination with respiratory triggering technology, are adopted for 3D volumetric acquisitions to obtain thin multi-slice images. The acquired images can then be reformatted using Maximal Image Projection (MIP). Advantages

The original thin-slice images are beneficial to display small lesions in the cavity for better reconstruction effect. Disadvantages

Relatively long scanning time. 2D Continuous Thin-Slice Scanning Single-shot turbo spin-echo T2W1 sequence plus segmented K-space imaging are used to speed up data acquisition; fat suppression technology is used to enhance tissue contrast. Advantages

• The original thin-slice images can be achieved, which is beneficial to display small lesions in the cavity. • The image can be post-processed in various ways. • The time required for scanning is relatively short. Disadvantages

• The slice thickness of images is larger than that of original images collected by 3D. • Inaccurate image registration may occur because of poor breath-holding or image distortion, thus affecting the quality of 3D reconstructed images. 2D Thick-Slice Projection Imaging The thick-slice block with a volume of 2 ~ 10 cm is excited and collected, and a projection image of the thick layer block is obtained by one scan. Advantages

Fig. 2.16  MRCP imaging of normal intrahepatic and extrahepatic bile ducts

• Only several seconds are needed for an image to be scanned. • The pipeline structure shows good continuity and step-­ ladder artifacts are rare.

2  Application of Multi-slice Spiral CT and MRI in Biliary Surgery

Disadvantages

• The image cannot be post-processed. • Original thin-slice images cannot be obtained. • Small lesions are easily omitted. In clinical practice, it is better to combine two or more above-mentioned methods with conventional MRI images. MRCP makes use of contrast agents to produce detailed pictures of ducts and organs. The produced images can be processed by multiplanar 3D reconstruction and the shape of the pancreaticobiliary tract can be clearly observed. The images can clearly display (a) the shape of obstructed end and state of the proximal hepatic bile duct branch of the obstruction, and (b) the variation and malformation of the biliary tract and biliopancreatic convergence abnormalities. Biliary dilatation is not affected by the pressure when injecting contrast agent, reflecting the true diameter of the cavity, without serious complications, and independent of technical operations. The disadvantages include: • The spatial resolution is insufficient and the microstructure of pancreatobiliary tract cannot be displayed. • Lesions with weak signals in the bile duct cavity (such as sediment-like stones, small lumps) are easily obscured during image reconstruction. • It is difficult to differentiate between bile duct lesions, including cholangiolithiasis, bubbles, polyps, and granulomas. • It is susceptible to intestinal effusion and ascites. MRCP cannot display bile duct wall as well as the extent of invasion and distant metastasis of extraluminal pathologies, nor provide comprehensive imaging information. It must be combined with conventional thin-­layer original image and enhancement examination.

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MRCP is accomplished by magnetic resonance hydrography of the shape and course of the pancreaticobiliary duct. When the lumen is completely wrapped by surrounding bile, showing a filling defect, the image is not clearly displayed, and the detection rate of stones is reduced. Therefore, the reconstructed image and original image of MRCP should be integrated for analysis in clinical examination; especially in small and sediment-like stones, blurring details in image reconstruction should be avoided so as not to affect the diagnosis. MRCP has a high diagnostic accuracy for the detection of choledocholithiasis and it can replace invasive and radiative diagnostic methods such as percutaneous transhepatic cholangiography (PTC) and CT colonography (CTC). MRCP has been widely used in the clinic; however, it has no therapeutic effect compared with endoscopic retrograde cholangiopancreatography. Therefore, diagnostic methods in clinical use should be selected according to the patient. In the diagnosis and differentiation of obstructive biliary tract disease, MRCP can display the shape of the obstruction site because of the correlation between the shape of the obstructive end and the nature of the lesion. Dependent on the obstruction level and the displayed features, combined with conventional plain and enhanced scans; obstructions caused by calculous, congenital, neoplastic, and inflammatory factors may achieve diagnostic and differential diagnosis (Vergel et  al. 2006). Because of its safety and non-­invasiveness, MRCP, is one of the most effective modalities for imaging biliary obstruction, providing a reliable basis for the diagnosis and treatment of biliary obstruction and postoperative surgical evaluation (Fig. 2.17).

2.3.3 Application of MRI in Biliary Surgery For biliary stones and inflammatory lesions, MRCP (Fig.  2.16) is a non-radiative and non-invasive imaging technique not requiring contrast agents. Through MRCP, the biliary tract system can be observed from multiple angles; location and size of biliary stones can be displayed; moreover, so-density or low-density stones that cannot be displayed on CT can be shown as well. Abnormities in the structure of the biliary tract can be clearly demonstrated. Patients who underwent biliary tract surgery or received cholangiopancreatographic examination with intubation failure can be well evaluated. The use of MRCP in combination with T1 weighted image (T1WI) can significantly increase the detection rate for small common bile duct stones. However, the examination of choledocholithiasis by

Fig. 2.17  Patient with cholangiocarcinoma, the common bile duct is transected, and the intrahepatic bile duct is visibly dilated

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References Andrew W. Chapter 1:The principles of magnetic resonance, and associated hardware. In: Magnetic resonance technology: hardware and system component design, pp. 1–47; 2016. Flohr T, Ohnesorge B.  Image visualization and post-processing techniques. In: Multi-slice and dual-source CT in cardiac imaging. Berlin: Springer; 2007. Goldman LW.  Principles of CT: multislice CT.  J Nucl Med Technol. 2008;36(2):57–68.

S. Zheng et al. Grover VPB, et al. Magnetic resonance imaging: principles and techniques: lessons for clinicians. J Clin Exp Hepatol. 2015;5(3):246–55. Miller CG, Joel K, Schwartz Lawrence H, editors. Medical imaging in clinical trials. London: Springer; 2014. p. 10–2. Nitz W. Principles of magnetic resonance imaging and magnetic resonance angiography. In: Reimer P, Parizel PM, Stichnoth FA, editors. Clinical MR imaging. Berlin: Springer; 2006. Vergel YB, Chilcott J, Kaltenthaler E, et  al. Economic evaluation of MR cholangiopancreatography compared to diagnostic ERCP for the investigation of biliary tree obstruction. Int J Surg. 2006;4:12–9.

3

Imaging of Common Biliary Tract Diseases Xianyue Quan, Shuping Qian, Zhendong Qi, Jingjing Huang, Liying Han, and Chihua Fang

3.1

Introduction

Both CT and MR imaging can be crucial for the final diagnosis of most biliary diseases, with both modalities allowing localization diagnosis, qualitative diagnosis, and detailed evaluation of the biliary tract (Yeh et al. 2009). Three-­dimensional reconstruction represented by CT and MRI plays a significant role in guiding precision surgery, providing important information for tumor infiltration characteristics, adjacent important vascular structures, variations, and quantitative evaluation. This chapter focuses on the imaging features of these two examination techniques in the diagnosis of biliary system diseases.

3.2

Congenital Biliary Diseases

3.2.1 Congenital Extrahepatic Biliary Atresia Congenital Extrahepatic Biliary Atresia (EHBA) is characterized by obliteration or discontinuity of the extrahepatic biliary tract, which is not accompanied by stones or tumors (Perlmutter and Shepherd 2002).

3.2.1.1 CT Features CT can clearly show the size of the gallbladder, the structure of the porta hepatis, and the signs of secondary portal hypertension. Absence of the gallbladder or small gallbladder has important diagnostic significance (gallbladder width 9  mm, this is called severe dilatation.

Moderate Extrahepatic Bile Duct Dilatation  Between mild and severe extrahepatic bile duct dilatation.

3  Imaging of Common Biliary Tract Diseases

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Fig. 3.65  CT findings of pancreatic segment obstruction. (a) Plain CT scan shows significant dilation of the intrahepatic bile duct; (b) Plain CT scan at different levels shows obvious dilation of intrahepatic bile duct; (c) Plain CT scan shows a concentric circular high-density stone in the pancreatic segment of common bile duct, with the above intrahe-

patic and extrahepatic bile ducts dilated; (d) Plain CT scan at different levels shows calculous shadow within the pancreatic segment of common bile duct, and the above intrahepatic and extrahepatic bile ducts are dilated. (e) The level of obstruction lies below the opening of the gallbladder, and the gallbladder is enlarged

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Fig. 3.66  CT findings of calculus in the pancreatic segment of common bile duct. (a) Plain CT scan shows a small high-density stone in the pancreatic segment of common bile duct, combined with cholecystolithiasis and cholecystitis (thickened gallbladder wall); (b, c) Contrast-­

enhanced CT scan shows branchlike dilated intrahepatic bile duct; (d) Contrast-enhanced CT scan shows stones in the pancreatic segment of common bile duct, bile duct dilatation, cholecystolithiasis, and thickening and strengthening of gallbladder wall

Severe Extrahepatic Bile Duct Dilatation  The extrahepatic bile duct loses its slender and “spindle-shaped” characteristics, and there is a feeling of fullness in the extrahepatic bile duct section. The diameter of the extrahepatic bile duct is more than 15 mm.

Residual Roots  The proximal end of the intrahepatic bile duct dilated more obviously, but the distal bile duct suddenly tapered toward periphery.

Morphology of Dilated Intrahepatic Bile Duct Dead Branches  (Fig. 3.69): Only a few bile ducts developed near the hilum of the liver, showing narrow strips, and gradually tapered off from front to back.

Soft Vines  (Fig. 3.70): The intrahepatic bile ducts dilated from the hepatic hilum to the peripheral liver, showing a distorted course.

3  Imaging of Common Biliary Tract Diseases

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Fig. 3.67  Lower segment of common bile duct—duodenal ampullary space occupation. (a) Plain CT scan shows intrahepatic bile duct dilation; (b) Plain CT scan shows that the gallbladder is enlarged, and a large soft tissue mass is seen in the lower segment of the common bile

duct; (c, d) Contrast-enhanced CT scan shows dilatation of intrahepatic bile duct, enlarged gallbladder, and slight dilatation of pancreatic duct; (e) CT enhanced scan shows that the mass shadows in the lower segment of the common bile duct are significantly enhanced

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Fig. 3.68  CT findings of ampulla obstruction (carcinoma of the head of pancreas). (a) Plain CT scan shows intrahepatic bile duct dilation; (b) Plain CT scan shows enlargement of the head of the pancreas, with a circular homogeneous mass shadow; (c) CT enhanced scan shows intrahepatic bile duct dilation; (d) Contrast-enhanced CT scan shows gallbladder enlargement, slight dilatation of the gallbladder inside and

outside the liver, and dilatation of the pancreatic duct; (e) Slight dilatation of the gallbladder inside and outside the liver, and dilatation of the pancreatic duct; (f) Contrast-enhanced CT scan shows a rounded soft tissue mass enhancement in the head of the pancreas with unclear boundary.

3  Imaging of Common Biliary Tract Diseases

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Fig. 3.69  Branch-like dilatation of the intrahepatic bile duct. (a) Plain CT scan shows branch-like dilatation of the intrahepatic bile duct; (b ~ c) CT Contrast-enhanced scan shows branch-like dilatation of the

intrahepatic bile duct; (d) MRCP shows branch-like dilatation of the intrahepatic bile duct, and a circular filling defect (choledocholithiasis) can be seen in the middle and upper segment of the common bile duct

3.5.3.2 Changes of the Distal End of the Dilated Extrahepatic Bile Duct

diagnostic significance (Saluja et  al. 2007) (Figs.  3.71 and 3.72). MRCP reveals that the edge of the obstruction terminal is irregularly narrowed. Centripetal and transverse stenoses are often malignant (Suthar et  al. 2015; Park et  al. 2004), while eccentric or cup-shaped stenoses are presumed to correspond to cholangiocarcinoma in most cases, and also, this condition can easily happen when there are calculi (Fig. 3.73). In this case, with or without enhancement in enhanced scan and thickening of the wall became the distinguishing feature. The stones were not strengthened, while cholangiocarcinoma had different degrees of enhancement at the obstructive end.

Abrupt Interruption and Irregular Tapering off the Dilated Extrahepatic Ducts CT images revealed tapering or disappearance of the dilated extrahepatic duct. The occurrence of this phenomenon with no positive stone shadow observed in the obstructed end is highly suggestive of malignancy; the association with an obstructive terminal mass or irregular wall thickening more than 4 mm also suggests malignancy, which has differential

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Fig. 3.70  Dilatation of the intrahepatic bile duct in the form of soft rattan. (a ~ b) T2WI: Soft rattan dilatation of intrahepatic bile duct; (c) MRCP shows soft rattan dilatation of intrahepatic bile duct and enlarged gallbladder

3  Imaging of Common Biliary Tract Diseases

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Fig. 3.71  Ductal adenocarcinoma of the head of the pancreas. (a) MRCP shows abrupt truncation of the pancreatic segment of the common bile duct and dilation of the intrahepatic and extrahepatic bile

ducts; (b) T2WI indicates intrahepatic bile duct dilation; (c) T2WI shows enlarged gallbladder, and dilatation of the upper segment of the common bile duct; (d) No calculi are found at the obstruction end

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Fig. 3.72  Ampullary adenocarcinoma involving the head of pancreas. (a) MRCP shows irregular narrowing and thinning of the lower segment of the common bile duct, with irregular filling defects, intrahepatic and extrahepatic bile duct dilation, and enlarged gallbladder; (b ~ c) T2WI shows gallbladder enlargement, dilated common duct, and sudden

tapering of the lower part of the common bile duct; (d) Contrast-­ enhanced CT scan shows enlargement of the head of pancreas, uneven enhancement, and small flaky low enhancement area; (e) Contrast-­ enhanced CT scan at different levels shows masses at the head of pancreas

3  Imaging of Common Biliary Tract Diseases

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Fig. 3.73  CT and MRI manifestations of calculi in the lower common bile duct. (a) MRCP shows abrupt truncation of the lower segment of common bile duct, and the above intrahepatic and extrahepatic bile

ducts are dilated; (b) T2WI shows a short T2 signal calculus shadow at the obstruction end; (c) Target signs (high-density stones in the dilated common bile duct filled with low-density bile)

Gradual Tapering of the Dilated Extrahepatic Bile Ducts On CT images, dilated bile ducts gradually tapered, with a range above 3  cm. This is the characteristic of benign obstruction (Fig. 3.74), such as that caused by inflammation (Katabathina et al. 2014).

3.5.4 A  nalysis of Obstructive Jaundice by CT and MRI

Masses at the Obstruction End  Masses at the obstruction end were mostly malignant tumors, and a few were chronic pancreatitis. The former are associated with necrosis in the mass and blurring of peripancreatic fat planes, while the latter are associated with pancreatic calcification and beading of the pancreatic duct.

3.5.4.1 Obstruction in the Early Phases Normally, bile duct dilatation can occur after obstruction of the common bile duct. Therefore, when obstructive jaundice and corresponding biochemical changes have occurred clinically, no bile duct dilatation may have formed yet. At this time, follow-up observation should be paid attention to. It has been reported in the literature that biliary dilatation can be observed 2 weeks after obstructive jaundice.

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Fig. 3.74  Cholangitis. (a) MRCP shows that the dilated pancreas in the upper segment of the common bile duct gradually becomes thinned into beak shape. The intrahepatic bile duct is slightly dilated, and stones can be seen in the intrahepatic bile duct and gallbladder; (b) T2WI

shows dilation of the upper segment of common bile duct; (c) T2WI shows gradual tapering of the middle segment of the common bile duct; (d, e) T2WI shows gradual tapering of the lower and middle segments of the common bile duct

3.5.4.2 Biliary Obstruction Associated with Liver Disease such as Diffuse Cirrhosis Due to liver inflammation, tissue fibrosis or extensive infiltration of tumor tissue, diffuse cirrhosis, and liver cancer can cause inhibition of intrahepatic bile duct dilatation.

Therefore, CT and MRI do not show the obvious dilation of intrahepatic bile duct when it is associated with extrahepatic bile duct obstruction; especially in the early phases of the disease, it is difficult to judge whether jaundice is obstructive at this stage.

3  Imaging of Common Biliary Tract Diseases

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99 Grand D, Horton KM, Fishman EK. CT of the gallbladder: spectrum of disease. AJR. 2004;183:163–70. Halefoglu AM. Magnetic resonance cholangiopancreatography: a useful tool in the evaluation of pancreatic and biliary disorders. World J Gastroenterol. 2007;13(18):2529–34. Hartley JL, Davenport M, Kelly DA.  Biliary atresia. Lancet. 2009;374:1704–13. Hashimoto M, Koide K, Arita M, et al. Acute acalculous cholecystitis due to breast cancer metastasis to the cystic duct. Surg Case Rep. 2016;2(1):111. https://doi.org/10.1186/s40792-­016-­0239-­1. Hundal R, Shaffer EA. Gallbladder cancer: epidemiology and outcome. Clin Epidemiol. 2014;6:99–109. https://doi.org/10.2147/CLEP. S37357. Hwang J, Chou Y, Tsay S, et  al. Radiologic and pathologic correlation of adenomyomatosis of the gallbladder. Abdom Imaging. 1998;23(1):73–7. Hwang H, Marsh I, Doyle J.  Does ultrasonography accurately diagnose acute cholecystitis? Improving diagnostic accuracy based on a review at a regional hospital. Can J Surg. 2014;57(3):162–8. https:// doi.org/10.1503/cjs.027312. Isherwood J, Oakland K, Khanna A. A systematic review of the aetiology and management of post cholecystectomy syndrome. Surgeon. 2019;17(1):33–42. Itai Y, Araki T, Furui S, et al. Computed tomography and ultrasound in the diagnosis of intrahepatic calculi. Radiology. 1980;136:399–405. Jarnagin WR, Weber S, Tickoo SK, et al. Combined hepatocellular and cholangiocarcinoma: demographic, clinical, and prognostic factors. Cancer. 2002;94:2040–6. Kane RA, Jacobs R, Katz J, et al. Porcelain gallbladder: ultrasound and CT appearance. Radiology. 1984;152(1):137–41. Katabathina VS, Dasyam AK, Dasyam N, et al. Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization. Radiographics. 2014;34(3):565–86. Kim YH. Extrahepatic cholangiocarcinoma associated with clonorchiasis: CT evaluation. Abdom Imaging. 2003;28:68. Kim SH, Park YN, Lim JH, et  al. Characteristics of combined hepatocellular-­cholangiocarcinoma and comparison with intrahepatic cholangiocarcinoma. Eur J Surg Oncol. 2014;40:976–81. Kimura Y, Takada T, Kawarada Y, Nimura Y, Hirata K, Sekimoto M, et  al. Definitions, pathophysiology, and epidemiology of acute cholangitis and cholecystitis: Tokyo Guidelines. J Hepato-Biliary-­ Pancreat Surg. 2007;14(1):15–26. Kowalski A, Kashyap S, Mathew G, et  al. Clostridial cholecystitis. [Updated 2020 Sep 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020. Lazcano-Ponce EC, Miquel JF, Muñoz N, et  al. Epidemiology and molecular pathology of gallbladder cancer. CA Cancer J Clin. 2001;51:349–64. Liu CL, Fan ST, Lo CM, et al. Hepatic resection for combined hepatocellular and cholangiocarcinoma. Arch Surg. 2003;138:86–90. Longmire WP Jr, Mandiola SA, Gordon HE. Congenital cystic disease of the liver and biliary system. Ann Surg. 1971;174:711–26. Mitchell D, Alam F.  Mangafodipir trisodium: effects on T2- and T1-weighted MR cholangiography. J Magn Reson Imaging. 1999;9(2):366–8. Munir K, Bari V, Yaqoob J, et al. The role of magnetic resonance cholangiopancreatography (MRCP) in obstructive jaundice. J Pak Med Assoc. 2004;54(3):128–32. Ng IO, Shek TW, Nicholls J, Ma LT.  Combined hepatocellular-­ cholangiocarcinoma: a clinicopathological study. J Gastroenterol Hepatol. 1998;13:34–40. Oliveria IS, Kilcoyne A, Everett JM, et al. Cholangiocarcinoma: classification, diagnosis, staging, imaging features, and management. Abdom Radiol. 2017;42:1637–49.

100 Paasch C, Salak M, Mairinger T, et al. Leiomyosarcoma of the gallbladder - a case report and a review of literature. Int J Surg Case Rep. 2020;66:182–6. Park MS, Kim TK, Kim KW, et al. Differentiation of extrahepatic bile duct cholangiocarcinoma from benign stricture: findings at MRCP versus ERCP. Radiology. 2004;233(1):234–40. Pavone P, Laghi A, Catalano C, et  al. Caroli’s disease: evaluation with MR cholangiopancreatography (MRCP). Abdom Imaging. 1996;21(2):117–9. Perlmutter DH, Shepherd RW. Extrahepatic biliary atresia: a disease or a phenotype? Hepatology. 2002;35:1297–304. Reilly DJ, Kalogeropoulos G, Thiruchelvam D. Torsion of the gallbladder: a systematic review. HPB (Oxford). 2012;14(10):669–72. Saluja SS, Sharma R, Pal S, et al. Differentiation between benign and malignant hilar obstructions using laboratory and radiological investigations: a prospective study. HPB. 2007;9(5):373–82. Savlania A, Behera A, Vaiphei K, et  al. Primary leiomyosarcoma of gallbladder: a rare diagnosis. Case Rep Gastrointest Med. 2012;2012:287012. Shaffer EA. Gallbladder sludge: What is its clinical significance? Curr Gastroenterol Rep. 2001;3(2):166–73. Shuto R, Kiyosue H, Komatsu E, et al. CT and MR imaging findings of xanthogranulomatous cholecystitis: correlation with pathologic findings. Eur Radiol. 2004;14(3):440–6. Singh A, Mann HS, Thukral CL, et al. Diagnostic accuracy of MRCP as compared to Ultrasound/CT in patients with obstructive jaundice. J Clin Diagn Res. 2014;8(3):103–7. Solmaz Tuncer A, Gürel S, Coşgun Z, Büber A, Cakmaz R, Hasdemir OA.  A rare presentation of xanthogranulomatous cholecystitis as Bouveret’s syndrome. Case Rep Radiol. 2012;2012:402768. https:// doi.org/10.1155/2012/402768.

X. Quan et al. Stephen AE, Berger DL. Carcinoma in the porcelain gallbladder: a relationship revisited. Surgery. 2001;129(6):699–703. Suthar M, Purohit S, Bhargav V, et al. Role of MRCP in differentiation of benign and malignant causes of biliary obstruction. J Clin Diagn Res. 2015;9(11):TC08–12. Todani T, Watanabe Y, Toki A, et  al. Classification of congenital biliary cystic disease: special reference to type Ic and IVA cysts with primary ductal stricture. J Hepato-Biliary-Pancreat Surg. 2003;10(5):340–4. Varadarajulu S, Zakko SF. Porcelain Gallbladder. UpToDate. Literature review current through: May 2013. | This topic last updated: Nov 09, 2012. Watanabe Y, Nagayama M, Okumura A, et  al. MR imaging of acute biliary disorders. Radiographics. 2007;27:477–95. Willén R.  Primary sarcoma of the gallbladder. A light and electronmicroscopical study. Virchows Arch A Pathol Anat Histol. 1982;396(1):91–102. Yamaguchi M. Congenital choledochal cyst. Analysis of 1,433 patients in the Japanese literature. Am J Surg. 1980;140(5):653–7. Yang H, Lee J, Yu M, et al. CT diagnosis of gallbladder adenomyomatosis: importance of enhancing mucosal epithelium, the “cotton ball sign”. Eur Radiol. 2018;28(9):3573–82. Yano Y, Yamamoto J, Kosuge T, et  al. Combined hepatocellular and cholangiocarcinoma: a clinicopathologic study of 26 resected cases. Jpn J Clin Oncol. 2003;33:283–7. Yee K, Sheppard BC, Domreis J, et al. Cancers of the gallbladder and biliary ducts. Oncology. 2002;16:939–46. Yeh BM, Liu PS, Soto JA, Corvera CA, et al. MR imaging and CT of the biliary tract. Radiol Clin N Am. 2009;29(6):1669–8. Yonem O, Bayraktar Y.  Clinical characteristics of Caroli’s disease. World J Gastroenterol. 2007;13:1930–3.

4

Introduction to 3D Visualization of Abdominal CT Images Susu Bao, Fengping Peng, and Chihua Fang

4.1

Introduction

4.1.2 Basic Techniques for 3D Visualization of Abdominal CT Images

This chapter introduces the development, procedures, and characteristics of the Medical Images Three-Dimensional Visualization System (MI-3DVS), a system that has independent intellectual property rights in China. It includes: • • • •

Procedures for data acquisition. Data pre-processing. Medical image segmentation. 3D realization and reconstruction.

4.1.1 B  asic Procedures for 3D Visualization of Abdominal CT Images As 3D visualization of abdominal CT images is an emerging field of research, it cannot be studied using traditional optical imaging research methods based on light intensity; therefore, new and targeted approaches are needed. The research content of 3D Visualization of Abdominal CT Images includes: medical CT data acquisition, data preprocessing, medical image segmentation, and 3D visualization. The basic processing procedure is shown in Fig. 4.1. CT image acquisition

Data preprocessing

Image analysis

3D visualization

Fig. 4.1  Flow chart of 3D reconstruction and visualization of CT data

S. Bao · F. Peng South China Normal University, Guangzhou, China

4.1.2.1 CT Acquisition Protocols CT data acquisition is different from acquiring general optical data. At present, CT data is acquired by ray tomography technology. Therefore, high-quality CT data can be achieved only through effective post-processing. 4.1.2.2 Data Preprocessing Compared with ordinary images, medical images are characteristically ambiguous and heterogenous in nature. Therefore, image preprocessing of CT data is required to obtain a better display effect, and the target area can be highlighted to prepare for the next segmentation. Common image preprocessing operations in CT include: grayscale windowing of CT images enhancement, and image format conversion. 4.1.2.3 Medical Image Segmentation The structure of medical images is complex, and the gray scale between different tissues is of high ambiguity and uncertainty. For some tissues and organs, their boundaries can hardly be distinguished by the naked eye. In order to compensate for these weaknesses and to accurately differentiate normal from abnormal tissues in medical imaging, it is necessary to perform image segmentation. Image segmentation plays an important role in medical applications; it is an indispensable means to extract quantitative information of distinctive structure from images; furthermore, it plays a key role in the realization of visualization. The commonly used segmentation approaches include threshold-based image segmentation, interactive image segmentation, and image segmentation based on active contour models or deformation models (Kang et al. 2020). Different segmentation techniques can be selected according to the varying characteristics of different medical target tissues and the image to be segmented.

C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_4

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4.1.2.4 3D Visualization There are two major approaches for 3D visualization of medical image data: surface rendering and volume rendering. Surface rendering firstly extracts the value of the object contour from the three-dimensional data field, then constructs the intermediate geometric elements (such as surface and plane) from the three-dimensional data field according to the values, and finally realizes the drawing by traditional computer graphic technology. Marching cubes is one of the most typical methods of such algorithms (Wang et  al. 2020), and this method can extract relatively clear isosurface (Cirne and Pedrini 2013). When the image is rotated, it does not need to retraverse the volume data. Moreover, the existing graphics hardware can be used to realize the rendering function, which accelerates the image generation and transformation process. However, the visualized graphics constructed by this method can only provide a thin outer shell of the object; it can neither reflect the full picture and details of the whole original data field, nor solve the issue of blurred boundary. Additionally, with the increasing size of the volume data, a large number of intermediate geometric primitives are generated, which requires a large memory space and slow drawing speed. Volume rendering does not require the construction of intermediate geometric primitives, and the volume data are directly projected onto the image plane to obtain the full picture and details of the volume data. The typical method is ray casting (Santos et al. 2020), which is a popular technique of volume visualization for the generation of high-quality and realistic images. It is particularly suitable for unshaped volumetric datasets such as clouds, fog, fluid, brain soft tissue, and gas; however, it is rather time consuming for each image to be generated to traverse the volume data.

4.1.3 Composition of MI-3DVS MI-3DVS consists of an abdominal medical center database, a medical image processing center, and a computer-aided surgical simulation platform (Fig. 4.2).

4.1.4 Advantages of MI-3DVS • The source data is from the current advanced 64-slice spiral CT. • Image data processing and simulation surgery are closely connected through STL files. • The simulation surgery platform which is based on the PHANTOM force feedback device with property rights for secondary development can form mechanical haptic feedback. • The image storage center can be used to conduct data mining and pattern recognition research on patient data.

S. Bao et al.

Data acquisition

computer-aided surgical simulation platform

Data Center

image processing center

Fig. 4.2  Diagram showing MI-3DVS operation

4.2

I mage Registration, Segmentation, and 3D Reconstruction

4.2.1 Image Registration Image registration refers to geometrically alignment of one image with another (Nicolas et al. 2020). After image registration, the two registered images should achieve spatial consistency; moreover, the different sets of data should be transformed into one coordinate system. The primary goal of image registration is to eliminate or suppress geometric discrepancies between the registered image and the reference image by applying a linear combination of translation, rotation, scaling, and shearing. Image registration is a crucial step in all image analysis and processing tasks; moreover, it is the prerequisite for image contrast, image fusion, change detection, and target recognition. In this chapter, triphasic CT scan of the liver was adopted (venous, portal, and arterial phases). Although the number of layers scanned is the same, the scan sequences are different. Thus, it is necessary to carry out three-stage registration so as to achieve complete fusion of the liver and its internal conduit. The image matching algorithms can be commonly divided into two categories: matching algorithm based on geometric pattern value and pixel gray value. On the basis of fully utilizing the characteristics of CT image data, combined with the existing template matching algorithm, a three-stage liver data registration algorithm based on the similarity of CT images is proposed, which effectively realizes the registration and fusion of three stages of liver data.

4.2.1.1 Template Matching Algorithm Template matching is the process of searching for small parts of a source image that match a template image. It is basically an approach for searching and finding the location of a tem-

4  Introduction to 3D Visualization of Abdominal CT Images

103

plate image in another image. The match is successful when the template is detected in the source image; otherwise, if there is a template to be searched in the source image with identical size and orientation to its template, the template image and its target coordinate position in the source image can be found through calculating the correlation function. In short, the primary goal is to find subgraphs and their location which are closet to the template image in the source image (Fig. 4.3). Assume the template T is translated on the source image S.  The subgraph template is called subgraph Si,j. i and j are coordinates of the pixel in the upper left corner of the M

M

M

subgraph in S, which is defined as the reference point. The search range is limited to 1 ≤ i, j ≤ N - M + 1; the correlation function that measures the level of similarity between the template T and the subgraph Si j can be obtained by the following similarity measures: Assume: M

M

D ( i,j ) = åå éë S i , j ( m,n ) - T ( m,n ) ùû



2

m =1 n =1

By expanding the above formula, we can also write this equation as:

M

M

M

D ( i,j ) = åå éë S i , j ( m,n ) ùû - 2ååS i , j ( m,n ) ´ T ( m,n ) + åå éëT ( m,n ) ùû m =1 n =1 m =1 n =1 m =1 n =1

M

where,

M

åå éëT ( m,n )ùû m =1 n =1

2

2

M

M

åå éëS ( m,n )ùû i, j

2

m =1 n =1

R ( i ,j ) =

represents the total energy of

the template, which is a constant and is independent of (i, j);



M

R=

M

i, j with the position of (i, j); 2ååS ( m,n ) ´ T ( m,n ) repm =1 n =1

resents the relationship between the template and the subgraph, which changes with the change of (i, j). This value is the largest when T and Si, j match. Therefore, the correlation function can be defined as:

Fig. 4.3  Source image (a) and Template (b)

2

(4.2)

å å S ( m,n ) ´ T ( m,n ) å å éëS ( m,n )ùû M

M

m =1

n =1

i, j

M

M

m =1

n =1

(4.3)

2

i, j

This equation can be transformed into:

is the energy of the subgraph to be

matched under the template cover, which changes slowly

(4.1)





{å

å å M

å

m =1

N n =1

S i , j ( m,n ) ´ T ( m,n )

M

M

m =1

n =1

éë S i , j ( m,n ) ùû

2

} {å

M

å

m =1

M n =1

éëT ( m,n ) ùû

}

(4.4) When the template matches the source subgraphs, there is R(i, j) = 1, otherwise R(i, j) SetDimensions(nDatax,nData y,nDataz);//Specify their dimensions, where

nDatax, nDatay, nDataz represent the image width, height and number of layers, respectively m_pStructuredPoints->SetOrigin(0,0,0);//Specify the origin m_pStructuredPoints->SetSpacing(1,1,1);// Specify the ratio of x, y, z in three directions pScalars->Allocate(nDatax*nDatay*nDataz);// Allocating space pScalars->SetNumberOfComponents(1); pScalars->SetNumberOfTuples(nDatax*nDatay*nDa taz); For(intnStart=0;nStartSetFileName(nStart filename);// Specify the file name, nStart Filename refers to the file name of the nStart sheet pBMPReader->Update();//Read data pBMPScalars(vtkDoubleArray*) pBMPReader->GetOutput0->GetPointD Ata()->GetScalars0; nOffset l=nStart*nDatax*nDatay;//inter-slice distance For(inti=0;iInsertValue(nOffset2,nScalar);// Insert grayscale information at the specified position } } m_pStructuredPoints->GetPointData0>SetScalars(pScalars); pScalars->Delete(); pBMPReader->Delete();

4.3.3 The Module for Image Segmentation

Fig. 4.13  System function modules

Image processing algorithms mainly include region growing and threshold segmentation methods. Region growing involves the selection of initial seed points and uses different segmentation approaches for segmenting different tissues. The vtkStructurePoints class was used to preserve

4  Introduction to 3D Visualization of Abdominal CT Images

the segmentation results, so that 3D reconstruction can be performed after segmentation. However, it should be noted that there are multiple segmentation results in memory after ­multiple segmentation. Those unnecessary volumetric data that have been segmented should be released in time according to the actual situation. The interface of region growing and threshold segmentation are shown in Fig. 4.14. IntnDx [] = {0, 1, 0, -1}; // four neighbors intnDy[]={-1,0,1,0j; / / Define the queue and save coordinates X and Y Int*pnGrowQueX= new int[nDatax*nDatay]; Int*pnGrowQueY=new int[nDatax*nDatay];//nDatax and nDatay represent the width and height respectively / / Define the start and end of the queue. When Start = End, there is only one point in the queue Int Start=O, End=0; / / Put the seed coordinate onto the front of the queue pnGrowQueX[End]=seed_X; pnGrowQueY[End]=seed_Y; While(StartGetValue(CurrentCord); / / The target image is identified as backcolor in advance. When the area meets the conditions If((CurrentResultValue==backcolor)&& (nSeedVal-CurrentSourceValue)SetValue(CurrentCord,foreco lor);//Set the pixel (xx, yy) to forecolor, indicating that the point is to be merged nSeedVal=nTotalPixelVal/(End+1);//The gray average of the previously divided regions } } } Start++; } //while Delete[]pnGrowQueX: Delete[]pnGrowQueY:

4.3.4 The Module for 3D Reconstruction In this module, contours, MC algorithms, maximum density projection algorithms, and ray casting methods are implemented using the functions provided by VTK.  Moreover, scaling, rotation, changing the color, adjusting the transparency, and segmenting tissue can be implemented on the reconstructed model. The user interface is shown in Fig. 4.15. When contour and marching cube algorithms are used for surface rendering, two functions are mainly involved: VtkContour Filter, the function for contour, and vtkMarchingCubes, the function for marching cubes. The key for unsegmented images is to set the value of the iso-surface. When the value is different, the reconstructed tissue is different. The specific steps by using MC method are as follows: • Use the vtkBMPReader class in VTK to read BMP files and save them in the vtkStructuredPoints class. • Use the vtkMarchingCubes class to set the value of the contour surface and extract the contour of interest. • Call vtkPolyDataMapper to map the data processed by vtkMarchingCubes to geometric data. • Define vtkActor, specify information such as lighting, view, and focal point of the scene, and then use the vtkRender class to render the entities in the scene. In the volume rendering algorithm, maximum intensity projection algorithm and ray synthesis algorithm are used, mainly involving vtkVolumeRayCastMIPFunction and vtkVolumeRayCastCompositeFunction. The effects achieved by these two algorithms are quite different. For the ray synthesis algorithm, how to set the mapping function is the key which determines the effect, that is, how to set the mapping relationship between grayscale and transparency and color values. VTK mainly involves three classes: vtkVolumeRayCastCompositeFunction, vkt piecewise Function, and vtkColorTransferFunction. Among them, vtkVolumeRayCastCompositeFunction defines a ray synthesis function,

114 Fig. 4.14 Segmentation interface. (a) Interface of regional growth algorithm; (b) interface of threshold segmentation algorithm

S. Bao et al.

a

b

and vtkPiecewiseFunction defines the mapping relationship between CT values and transparency values in a piecewise manner, while vtkColorTransferFunction is a transformation function that defines the CT value and the color value. The specific steps for using ray casting are as follows: • Read the sequence BMP files with the vtkBMPReader class in VTK, and store their information in the vtkStructuredPoints class. • Set its CT value to transparency and color value mapping, the vtkPiecewiseFunction class and vtkColorTransferFunction class are mainly used.

• Use the vtkVolumeRayCastMapper class to achieve data mapping. • Define the vtkVolume Actor, specify information such as scene lighting, view, and focus, and then use the vtkRender class to render the entities in the scene.

4.3.5 The Module for 3D Model Exporting MI-3DVS integrates image segmentation with 3D reconstruction to form a simple 3D visualization system. The system meets the basic requirements of data visualization of the abdomen, such as 3D visualization of liver, blood vessel,

4  Introduction to 3D Visualization of Abdominal CT Images

115

Fig. 4.15  Reconstruction interface

and spleen. Three-dimensional reconstructed models can be saved in this module, so that these models can be brought up directly afterward without the need for re-segmentation and reconstruction. The saved formats include STL, PLY, and OBJ. At the same time, the module also realizes the function of saving any image data of the volume data. However, for some complex pipelines, such as the gastrointestinal tract, the system is still unable to separate them well.

References Cirne MVM, Pedrini H. Marching cubes technique for volumetric visualization accelerated with graphics processing units. J Braz Comput Soc. 2013;19:223–33.

Kang SH, Won Y, Lee K, Youn SI, Min S-H, Park YS, Ahn S-H, Kim H-H. Three-dimensional (3D) visualization provides better outcome than two-dimensional (2D) visualization in single-port laparoscopic distal gastrectomy: a propensity-matched analysis. Langenbeck’s archives of surgery; 2020. Nicolas G, Fabio C, Daniel A, Reto S, Guoyan Z, Philipp F. Evaluation of CT-MR image registration methodologies for 3D preoperative planning of forearm surgeries. J Orthop Res. 2020;38(9):1920–30. Pattana S, Sakuntam S, Kentaro O. Selective-area growth and characterization of cubic GaN grown by metalorganic vapor phase epitaxy. Thin Solid Films. 2020;709:138205. Santos J, Oliveira MR, Arrais R, Veiga G. Autonomous scene exploration for robotics: a conditional random view-sampling and evaluation using a voxel-sorting mechanism for efficient ray casting. Sensors. 2020;20(15):4331. Wang J, Huang Z, Yang X, Jia W, Zhou T. Three-dimensional reconstruction of jaw and dentition CBCT images based on improved marching cubes algorithm. Procedia CIRP. 2020;89:214–21.

5

Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery Chihua Fang and Zhaoshan Fang

5.1

Introduction

Although 3D printing was already proposed in the nineteenth century to produce topographic maps layer by layer, the first real attempts to generate objects that way were made in the 1980s. Swainson of Denmark proposed a process to directly fabricate a product by selective 3D polymerization of a photosensitive polymer (Swainson 1977). In 1979, Nakagawa of Tokyo University reported the use of lamination techniques to produce actual tools (Nakagawa et  al. 1979). In 1981, Hideo Kodama of the Nagoya Municipal Industrial Research Institute (Nagoya, Japan) first proposed the protocol of a functional photopolymer rapid prototyping system (Kodama 1981). The United States and Japan pioneered the practical development of real 3D printing technology. In 1986, Charles Hull founded 3D Systems, Inc., and this company developed the stereolithography (STL) file format; in 1988, 3D Systems introduced the world’s first commercial 3D printing system, the SLA-250 (Ventola 2014). It was in the year 1988 that Scott Crump invented and patented a new 3D printing method called Fused Deposition Modeling (FDM); Crump went on to found Stratasys, Inc., and this company developed the first FDM 3D printer in 1992 (Bagaria et al. 2018). Traditional manufacturing mainly uses the principles of mechanics, temperature, and pressure. Generally, the technical process of production can be divided into cold scrap removing and thermal deformation processes. Common operations including shearing, grinding, corrosion, and melting are used to remove the redundant parts and to obtain the shape of components. These individual components are then assembled and welded into final products. Additive manufacturing represented by 3D printing technology and

C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China Z. Fang The Fifth Affiliated Hospital of Guangxi Medical University, Nanning, China

rapid prototyping is an “integrated” high-tech developed in the 1980s, which combines computer, CNC technology, laser technology, CAD/CAM, and materials science in one. Compared with traditional manufacturing methods which involve removing parts of a block of material to form the desired shape, 3D printing technology produces far less material waste since it only uses the material necessary to create a part. The manufacturing cycle by conventional methods usually takes a long time, and the shape of sloped surfaces and deep slots are difficult to produce; while additive manufacturing, also known as 3D printing makes up for the shortcomings of the above traditional manufacturing processes, showing its tremendous advantages of “green technology.”

5.1.1 Principles and Concepts of 3D Printing 3D printing, also known as rapid prototyping, refers to advanced technology for manufacturing 3D objects by stacking layers of defined sheet materials such as metal and plastic. 3D printing technology is mainly used to “manufacture” products by means of layering processing and superposition through computer control, and its core is the combination of digital, intelligent manufacturing, and materials science. 3D printing is fundamentally different from traditional manufacturing. It has opened a new era of manufacturing and has been hailed as the foundation of the “Third Industrial Revolution” by The Economist.

5.1.1.1 Principles and Workflow of 3D Printing Principles of 3D Printing 3D printing involves a rapid prototyping device generating 3D objects by successively “printing” thin layers through stacking sheets of paper and photocuring technology. The mechanism of 3D printing resembles that of the ink-jet printer. A 3D model is first produced using 3D design software, and then the drawings are bundled up into a G-code

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_5

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file, the native language of a 3D printer. The G-code is then sent to the 3D printer where it is generated into a 3D printout. In 3D printing, the printer generates the object by adding layer upon layer of material until the shape of the object is formed. The object can be produced using various adhesive printing materials, including metal or plastics. 3D Printing Workflow There are four typical phases to obtain a physical object by 3D printing technology: modeling, slicing, printing, and post-processing. Modeling  There are two main methods of 3D modeling for 3D printing. One is to directly create 3D digital models using software such as AutoCAD, 3Dmax, and Blender; the other is to first acquire 3D data of the object using a 3D scanner such as Polhemus, 3D CaMega, and Z Corp., and then those data are processed to generate a digital 3D model. Slicing  In 3D printing, the virtual 3D model needs to be sliced into corresponding 2D graphics and then the 2D graphic information is printed. The thickness of the slice is determined by the properties of printing materials and specifications of the printer. Printing  There are a continually expanding group of processes used in 3D printing. Essentially building up layers and fusing, either with an adhesive, or by applying energy to fuse the substrate. The substrate may be in a vat if liquid, in a bed of powder, or extruded from a ‘print head’. Applied energy is in the form of heat, where the substrate is either extruded in molten form by the printer and fused in situ, or by the application of energy such as infra-red, UV light, Laser or Electron beam. Solid objects can also be produced by materials such as alloy powders applied layer by layer and sintered in situ.

C. Fang and Z. Fang

Fused Deposition Modeling By using this technology, a continuous filament of thermoplastics such as acrylonitrile–butadiene–styrene nylon and wax, is heated in a liquefier into a semifluid state. Under the control of a computer, a wide variety of these semifluid materials are extruded by a 3D printer extruder according to the cross-sectional profile information. After the object is solidified, a single layer of the desired model is formed; by deposing material layer by layer, the final product is achieved. A representative company using such technology is Stratasys. Stereolithography SLA uses photopolymer resin as the printing material. A computer-guided ultraviolet (UV) laser is used to scan the photopolymer resin. The print is gradually lifted and new layers are printed (fixed by the UV laser) from below. Since the photopolymer resin is sensitive to UV light, the resin becomes photochemically solidified, stacking layer upon layer of material to form the final object. Generally, the material used is a liquid photopolymer resin, and the representative company is 3D Systems. Selected Laser Sintering Under laser irradiation, the powdered materials become sintered. According to the information of interface profile, selective sintering is carried out under the control of computer to accumulate and shape the parts. The typical working materials for this process include metal powder, ceramic powder, and thermoplastics. The representative companies include 3D Systems and EOS. Direct Metal Laser Sintering DMLS uses a high-wattage laser to melt and fuse a layer of alloys and metallic powders together, and the process should be repeated layer after layer until the part is completed. This technique is based on alloy metals. Representative enterprises include EOS and MT.

Post-processing  After printing, residues of printing materials can cling or remain in the model, and the object normally comes out of the printer with burrs uneven surface. In view of these issues, excess powders can be removed manually, and the burrs and rough surface can be polished; afterward, the 3D physical model should be glued to enhance the hardness; finally, coloring should be performed before a final product is achieved.

Laminated Object Manufacturing In LOM, the working material consists of a roll of thin “laminate.” A laser cuts the outline from a slice of the original image. A heated roller presses the laminate cutting onto the previous layer, the laminate roll moves forward and the next layer is cut, heat rolled, and the process continues. Materials used include plastic, paper, or aluminum foil. Representative companies include Helisys and Kinergy.

5.1.1.2 Types of 3D Printing Technologies Currently, 3D printing mainly includes fused deposition modeling (FDM), stereolithography (SLA), selected laser sintering (SLS), direct metal laser sintering (DMLS), laminated object manufacturing (LOM), electron beam melting (EBM), and three-dimensional printing (3DP).

Electron Beam Melting The EBM process manufactures parts by melting metal powder layer by layer with an electron beam under a vacuum. Generally, the working material is a titanium alloy, and the representative company is Arcam AB.

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

Three-Dimensional Printing 3DP is a printing process using a droplet ejection method. Through an ink-jet printing head, a liquid binder is sprayed into a layer of powder, and then the binder is solidified, forming a solid layer. This layer-by-layer process repeats until the desired model is formed. Generally speaking, colored plaster is used as the representative material, and the representative company is 3D Systems.

5.1.1.3 Technical Requirements of Medical 3D Printing Only through high-quality original CT images and high-­ fidelity 3D reconstructed model can we obtain a high-­ precision and high-fidelity printed physical model. Therefore, there are three technical requirements regarding the printing of a 3D physical model for hepatobiliary and pancreatic diseases. Acquisition of High-Quality Thin-Slice CT Images in DICOM Format The quality of CT data can be affected by (a) the parameters of original data acquisition, (b) the quality, dose, and injection speed of contrast agent, and (c) module function of different software. Therefore, clinicians, radiologists, and technologists should work together to optimize parameters, so as to collect high-quality thin-slice CT images (Thin slices, as used herein, refers to medical images with a thickness of 0.625–1.5  mm), so as to obtain CT data with better contrast (good signal-to-noise ratio), which is very important in 3D modeling. The quality of CT data directly affects the accuracy of the subsequent 3D visualization model of liver, bile, and pancreas.

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segmentation, registration, 3D reconstruction, and visualization display; and it is related to different algorithms or methods of computer image and graphics processing. The processing or calculation of the above different steps may result in the loss of original data, thereby affecting the precision of the reconstruction. Therefore, the requirements of high-fidelity for 3D printed objects can be satisfied by optimizing the algorithms of various reconstruction methods and improving the fidelity of 3D reconstruction.

5.1.1.4 Benefits and Drawbacks of 3D Printing in Medical Applications Advantages of 3D Printing High printing accuracy, constant prototyping and enhanced productivity, customization and personalization, and cost reduction. Disadvantages of 3D Printing Challenges of 3D printing include limited size of objects, limited raw materials, and restriction on printing high-­ precision instruments. There are potentially deficiencies in medical 3D printing, especially in 3D printing of hepatobiliary and pancreatic models:

• CT image quality affects the quality of the printed model. 3D printed models can be produced by CT-based volumetric medical images. Loss of details in DICOM images may inevitably lead to distortion in 3D modeling, which in turn directly results in information loss in the preparation stage of printing. The above three situations may cause different degrees of distortion in the 3D printed Construction of High-Fidelity 3D Models object. CT value is the basis of images. The 3D modeling process • The 3D printer and printing materials affect the quality of may inevitably lose details in the original raw data, which the model. The performance of the printer affects the leads to distortion of the 3D reconstruction accordingly. quality of the printed model; the type, texture, and Using 3D visualization technology, 3D reconstruction is properties of printing materials also affect the performance, performed by preprocessing, image segmentation, surface transparency, tissue elasticity, and stability of 3D printed rendering, and volume rendering of the original DICOM objects. data. This secondary processing of the original 2D images • 3D printing is expensive and time-consuming. Igami et al. may lead to some degree of image distortion. In order to (2014) believed that it takes about 18 h and approximately reduce image distortion, it is necessary for a Hepato-biliary-­ 50,000 ¥ to print a 3D liver at a scale of 70%; the printing pancreatic surgeon who has mastered the 3D reconstruction time and cost could increase twofold; moreover, 2–3 days software and who is competent and experienced in film are required for post-processing. Zein et al. (2013) pointed reading to analyze the image and reconstruct the 3D model. out that it takes about 25–40 h to print a liver 3D model. Only in this way can the 3D printed model be faithful to the Printing a liver model can take up to 2 days plus one more original data of CT. for post-processing (Kuroda et al. 2017), and the cost of printing material ranges between $500 and $800. The cost High-Performance 3D Reconstruction Software in time and money are factors that restrict the conventional The performance of the 3D reconstruction software affects application of 3D printing in hepatobiliary and pancreatic the fidelity of reconstruction. 3D visualization technology surgery. 3D printing is only suitable for some screened involves multiple steps including image data preprocessing, patients, not for emergency patients.

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5.1.1.5 Applications of 3D Printing In the current scenario, 3D printing has facilitated advances in industrial manufacturing, custom art, aerospace, and biomedical industries. “Urbee,” the world’s first 3D printed car was created by Ecologic and Stratasys in November 2010; SULSA, the world’s first 3D printed aircraft was developed by engineers at the University of Southampton in August 2011; in November 2012, the world’s first 3D printed artificial human liver tissues were created by Scottish scientists; in October 2013, a 3D printed artwork nicknamed “the God of ONO” was successfully auctioned; in November 2013, a Texas company by the name of Solid Concepts has manufactured the world’s first 3D printed metal gun; In China, a large-scale integral titanium alloy key main load-­ bearing part has been successfully produced by the Beijing University of Aeronautics and Shenyang Aircraft Design Institute, and this project won the first National Award for Technological Invention in 2012, which made China the first country in the world to successfully install such components into engineering applications. These high-tech products have promoted the development of 3D printing technology into a new era.

5.1.2 Medical Applications for 3D Printing The rapid development of 3D printing technology has promoted its application in the medical field. Correspondingly, advances in medical 3D printing technology have made tremendous contributions to clinical repair and treatment, medical model manufacturing, tissue organ regeneration, and drug development and testing.

5.1.2.1 Clinical Repair and Treatment Medical implants produced by 3D printers can better integrate into the human body and improve therapeutic efficacy. In March 2014, three bone tumor patients were treated in Xijing Hospital, The Fourth Military Medical University, Xian, China. Their bone defects, in different locations were repaired by implantation of customized 3D printed titanium alloy prosthesis. This was the first clinical application of 3D printed titanium scapula prosthesis and clavicle prosthesis in the world, and the first application of pelvic prosthesis in Asia (Fan et  al. 2015). In August of the same year, The Department of Orthopedics of the Peking University Third Hospital completed the first worldwide treatment for atlantoaxial malignant tumor by 3D printing technology, which has opened up a new way to reconstruct cervical vertebral structure after tumor resection. 5.1.2.2 Medical Model Manufacturing Medical models have been extensively used in the teaching of basic medicine and clinical trials. However, the traditional

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method of producing medical models is complicated and time-consuming and they are easily damaged because most of their raw materials are plaster. In recent years, the use of corpses for medical anatomy teaching has become more and more ethically debated and socially controversial. With the progress of 3D printing technology, printed physical models can be used for anatomical teaching. Medical experimental models not only help avoid the above problems, but also realize the personalized manufacturing of special models according to specific needs. After obtaining DICOM data based on MSCT scanning for different parts of the human body, the data can be reconstructed into file formats such as STL, VRML, and PLY by 3D reconstruction software; any human organs can be replicated by a 3D printer. By using 3D printing technology, any anatomical parts, including upper limbs, hands, coronary arteries, and trachea can be printed into physical models, and these models can provide more information than 2D images.

5.1.2.3 Tissue/Organ Regeneration How to build replacement tissues and organs remains a challenging problem in clinical medicine? Many end-stage (tumor) patients in need of organ replacement have lost their lives because of the persistent organ shortage. As science and technology continue to evolve, 3D printing of human organs is becoming possible and will moderate the disparity between organ supply and organ demand. 3D printing of some viable organ components has already become possible. In 2013, a US military funded research made a major breakthrough on 3D printing for skin and kidney. More recently, German researchers have produced flexible artificial blood vessels using 3D printing technology; these vessels can fuse with human tissue, not only to avoid rejection, but also to grow muscle-like tissue. These successful cases suggest that it is becoming possible to address the current and future artificial organ shortages by 3D printing. 5.1.2.4 Development and Testing of Drugs At present, most of the drug testing is carried out on laboratory animals. It is difficult to get accurate feedback of pharmacological effects on humans. The human liver, kidney, and specific cell tissues printed by 3D technology for the testing of new drugs can not only truly simulate the human body’s response to drugs, but also obtain accurate test results, which can reduce the initial development cost. In 2013, Organovo, Inc. printed a miniature liver with a depth of 0.5 mm and a width of 4 mm using a 3D printer. Twenty layers of liver cells and vascular wall cells were printed by a bioprinter in a layer by layer manner. The 3D bioprinted mini livers can perform all of the many vital life functions of a real human liver, including metabolism of proteins and cholesterol, enzyme activation, and excretion of drugs. The undeniable benefits of 3D bioprinted liver models are gradually being highlighted

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

in new drug development and drug toxicology testing. Although several issues remain to be addressed, it is anticipated that 3D printing will continue to evolve and play an essential role in liver tissue engineering.

5.2

 D Printing for Hepato-Biliary-­ 3 Pancreatic Diseases

The basic steps of 3D printing for surgical diseases of the liver, pancreas, and biliary tract are as follows: upper abdominal thin-layer DICOM data acquisition, 3D digital preparation, 3D physical model printing, and 3D printing post processing (Fig. 5.1).

5.2.1 Acquisition of CT Data An enhanced thin-layer scanning of the liver, bile, pancreas, spleen, and abdominal vessels in the upper abdomen was performed by Multidetector Computed Tomography (MDCT) or an enhanced thin-layer of MRI.  Multiphase images (plain scan phase, arterial phase, portal venous phase, and delayed phase) were obtained with an image slice thickness of 0.625– 1.5 mm. Data was archived in the DICOM format.

5.2.2 Digital Preparation Thin-layer CT data were first processed by a post-processing workstation, and then imported into a 3D visualization software system (such as MI-3DVS, China; Mevis, Germany; or MIMICS, Materialise, Belgium) for program segmentation and reconstruction. Note: careful and accurate reading and analysis of CT images before 3D reconstruction are important to ensure the accuracy of 3D modelling. The DICOM data were analyzed, fused, calculated, segmented, and rendered by a 3D software system. The shape and spatial distribution of the liver, biliary tract, blood vessels, and lesion were described and interpreted; 3D image models of intrahepatic vessels and lesion were obtained and exported to a ­mesh-­type file (stereolithography (STL) file), or in other formats, such as VRML and PLY. These files were prepared for 3D printing. Files in STL format were acquired and further processed by Materialise Magics software in order to (a) assess the accuracy of intersecting vessels and bile ducts arising from subtle time or position artifacts between CT imaging phases, thereby generating nonoverlapping geometric figures, (b) perform hollowed vascular and bile duct structures, and (c) divide liver mesh structure (stereolithography (STL) file) into graft and remnant parts according to the proposed surgical resection plane.

3D reconstruction 3D data DICOM

3D physical model 3D printing post-processing

Fig. 5.1  Flow chart of 3D printed physical model

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3D printing

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5.2.3 3  D Printing for Hepato-Biliary-­ Pancreatic Diseases The STL files produced through digital preparation were imported into a 3D printer (such as Connex 350 3D printer, Stratasys; or 3D Printer, AGILISTA-3100, Keyence Co.; Spectrum ZTM 510 3D Printer, Z Corporation) for printing 3D physical models of intrahepatic and extrahepatic biliary tract, blood vessels, and lesions (Figs. 5.2, 5.3, 5.4, and 5.5). Liver parenchyma can be made of transparent materials such as Tango or Vero, or jelly wax; hepatic vein structure can be Tangoblack or Veroblue; other vessels can be mixed with transparent materials such as Tango or Vero; ZP 150 powder can also be used for printing.

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cured using a curing agent Z-Bond90 (3D Systems, USA). The physical model of the hepatic parenchyma shell and the model of the hepatic ducts are assembled to form the casting mold. The liquid transparent wax is injected into the mold. After solidification, the outer casting should be removed to obtain the transparent 3D physical model.

5.2.4 Post-Processing of 3D Printing Post-processing of 3D printed physical models for surgical diseases of the liver, pancreas, and biliary tract mainly involves reprocessing of the support materials and vessels. For example, after 3D physical models are printed by the Connex 350, removing support or excess material from the 3D print is a necessary step; the vessels are injected with color dye by a water gun, and the liver surface is coated to obtain visualized intrahepatic bile duct and vascular structure. After 3D physical models of intrahepatic bile ducts, blood vessels, and lesions are printed by the Spectrum ZTM 510, excess powder of the 3D print should be manually removed; and then the surface of the model should be osmotically

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Fig. 5.3  Front view of 3D printed model of hilar cholangiocarcinoma. Note: Green for intrahepatic dilated bile duct system, orange for hilar tumor, dark blue for portal vein system, and red for celiac artery system

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Fig. 5.2  3D printed model of intrahepatic vessels and tumors of central HCC. (a) Front view; (b) back view. Note: Dark blue for hepatic vein system, pink for portal vein system, and red for celiac artery system

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

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Fig. 5.4  Front view of 3D printed model of hepatolithiasis. (a) 3D printed model of left intrahepatic calculi; (b) 3D printed models of left and right hepatic calculi. Note: Red for the celiac artery system, dark

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blue for the hepatic vein system, green for the dilated bile duct, light blue for the portal venous system, and white for hepatolithiasis

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Fig. 5.5  3D printed physical model of ampullary tumor. (a) Front view; (b) back view. Note: Dark brown for the ampullary tumor, dark blue for the portal vein system, green for the dilated bile duct system, and red for the celiac artery system

5.3

 pplication of 3D Printing A for Complicated Hepato-Biliary-­ Pancreatic Surgery

With the development of computer technology, 3D visualization technology for 3D modelling has become an important auxiliary tool for planning surgically complicated hepatobiliary and pancreatic surgery. This technology has more

advantages than conventional CT and MRI 2D imaging. However, 3D images reconstructed based on the patient’s MDCT data are usually displayed on a 2D computer monitor, so the true depth perception response is limited, and different physicians have different perceptions of the spatial anatomical relationship between blood vessels and liver tumors. 3D physical printing of images based on 3D visualization has broken through this bottleneck. By observing 3D

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physical models, the accurate spatial anatomy of the hepatobiliary and pancreatic vessels and lesions can be obtained. The 3D physical models restore the real spatial position of the intrahepatic vessels, provide more detailed information for real-time surgery, and reduce potential complications of surgery; furthermore, these models can be brought into the operation room and placed in an appropriate place to provide an intuitive navigation for the key steps of hepatobiliary and pancreatic surgeries. In addition, the printed 3D models and the patient’s hepatobiliary and pancreatic organs can be synchronously adjusted in the process of surgical anatomy and organ separation; thus, the key anatomical sites can be quickly identified and located. By establishing a high-precision preoperative model or intraoperative template, the technique can improve surgical precision and reduce surgical trauma, thus conforming to the modern concept of precision surgery. During surgical planning, the 3D physical model can be used for patient assessment, surgical protocol formulation, and simulation operation; at the same time, the 3D printing model can be applied to guide the operation in real time, which ensures a more precise and safer operation. Moreover, these 3D printing applications enable a better doctor–patient communication and increase the trust between the two parties because they enable patients and their relatives to intuitively understand the surgical plans and risks.

5.3.1 A  pplication of 3D Printing in Liver Surgery 5.3.1.1 In Complex Liver Resection At present, there are various definitions for complex liver tumors: • Centrally located hepatocellular carcinoma involving the porta hepatis. • Tumors with variations of hepatic artery, portal vein, and hepatic vein within the liver. • Intrahepatic vascular malformations caused by severe tumor compression. • Hepatic malignancy with tumor thrombus in the inferior vena cava and/or right atrium. • Large benign or malignant liver tumors requiring extensive hepatectomy. • Liver tumor encroaching on hepatic segments I and VIII that need to undergo complex liver resection. Because of the complex vascular structure and their variations, it is necessary to (a) understand the variations of hepatic vessels in hepatic surgery, and (b) locate the position of liver tumor and liver vessels precisely before operation. The 3D printing application of a liver model can truly display the location, size, and shape of the tumor; moreover, the relationship between the tumor and vessels can be observed from all direc-

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tions. 3D models present the features of organs as in  vivo, which can provide intuitive real-time indirect navigation during surgery and help to quickly identify and locate the key parts. 3D printing can make the anatomy of the complex hepatectomy clearer and the operation more precise and controllable. Clinically, the Couinaud liver segmentation method is the result of in vitro liver cast studies, and its concordance with most cases is only 20% to 30% (Cho et al. 2005). Individualized hepatic segmentation can be carried out based on an individual patient’s blood flow topology by using 3D visualization technology for the study of hepatic segmentation. The hepatic segment of each functional area is determined by the independent portal vein blood supply and hepatic venous reflux. Accurate division of conventional and abnormally distributed liver segments facilitates a more intuitive and accurate response to the spatial location of tumor lesions. For patients with complex liver tumors requiring hepatectomy, 3D printed liver segmentation based on hepatic vein and portal vessels are more conducive to planning for surgery (Fig. 5.6). Igami et al. used a 3D print of the liver for hepatectomy, which indicates that the application of 3D printing is very helpful in guiding real-­time hepatectomy (Igami et al. 2014). The authors believe that 3D image reconstructions based on patient MDCT data are usually displayed on a two-dimensional screen; different physicians have different perceptions of the spatial anatomical relationship between vascular and hepatic tumors; however, by observing 3D printed physical models, all physicians can identify them. In order to complete the resection of liver segments VII and VII, which are located under the apical part of the right diaphragm (special site), the right hepatic ligament should be dissociated and the deep vascular structure of the hepatic segment should be dissected. For such a complex liver resection, 3D printing is invaluable. A 3D print of the liver is beneficial for anatomical hepatectomy. A 3D model can help locate the key parts of the deep vascular structure of the liver, and thus contribute to a successful operation. Yamazaki et al. believed that the relationship between hepatic vessels and tumor was the most important spatially adjacent relationship in hepatic anatomical hepatectomy (Yamazaki and Takayama 2019). In their study, a simplified 3D printed model (printing the lesion and its surrounding blood vessels) was used to guide anatomic hepatectomy in real time for hepatocellular carcinoma at segment VII. By intraoperative navigation of the 3D print model, the Glisson pedicle of segment VII was found and thus, the anatomical liver resection of segment VII was successfully performed. For liver tumor at segments IV and VII involving the middle hepatic vein, anatomical radical resection of segment IV and the ventral anterior hepatic region were successfully carried out by using a simplified 3D printing model. This study indicates that a mere 3D print of hepatic vessels and tumor lesions is effective in guiding anatomical hepatectomy, and such a 3D printed model is helpful for all liver surgeries. Professor Fang Chihua’s team applied 3D printing technology to preoperative planning and intraopera-

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

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Fig. 5.6  3D visualization of liver segments based on topological drainage of hepatic veins and portal veins. (a) Front view; (b) diaphragmatic surface view. Note: Red for the celiac artery system, dark blue for the

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hepatic vein system, light blue for the portal vein system, and magenta for the ventral side of the liver.

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Fig. 5.7 (a, b) 3D printed model of complex liver cancer; front view. Note: Red for the celiac artery system is in red, dark blue for the hepatic vein system, and light blue for the portal vein system

tive guidance of 22 patients undergoing complex liver resection (Xiang et  al. 2015). Their results showed that the 3D printed model can stereoscopically display the spatial relationship between liver tumor and intrahepatic vessels, help to define the liver pre-resection surface, and ensure accurate operation. Fang et al. used 3D visualization and 3D printing physical models for preoperative planning and evaluation of liver volume, as well as for guiding the successful operation of right lobe massive liver tumors with vascular variability. In this case, if right hepatectomy was performed according to conventional surgery, the residual liver volume would be 41%, theoretically; however, due to vascular variations (portal vascular variation in hepatic segment IV arising from the right

anterior branch of the portal vein), conventional right hepatectomy would result in no portal blood supply in segment S4 (ischemia), which would result in insufficient postoperative residual liver volume (residual liver volume was 21%). Using 3D visualization and 3D printing for preoperative surgical planning and intraoperative 3D printing for surgical navigation, reduced right hepatectomy was performed and the portal blood supply of segment IV was retained. The operation was successful and the patient recovered smoothly. This case study shows that liver 3D printing assisted surgery for massive liver tumor with variations in portal veins is a safe and effective method to improve the success rate and reduce the risk of surgery (Fig. 5.7).

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5.3.1.2 In Liver Transplantation Many severe hepatobiliary diseases can lead to liver failure at the end of the period and liver transplantation may become the only treatment option. These diseases include primary sclerosing cholangitis, cholangiocarcinoma, diffuse intrahepatic cholelithiasis, end-stage biliary disease, and childhood congenital biliary disease. With further improvements in transplant surgery and surgical techniques, severe hepatobiliary disease will be treated by liver transplantation more often. The complexity of the hepatic vascular system poses a challenge to liver transplantation. By using 3D visualization and printing technology, the intrahepatic vascular and biliary structures can be observed stereoscopically and the donor and recipient’s hepatic vascular anatomy can be well known before operation. Zein et al. carried out a research on the application of 3D printed intrahepatic conduit physical models in living donor liver transplantation (Zein et  al. 2013). Three donor livers and three recipient livers were printed into 3D translucent models and these models were used for preoperative planning and intraoperative indirect navigation. 3D physical models help to understand the anatomical relationship between hepatic vessels and bile ducts, and to shorten the operative time and surgical complications. The liver model was compared with the resected real liver; the average deviation of the 3D model (length, width, and height) was less than 4  mm, and the average deviation of vessel diameter was less than 1.3 mm. Ikegami et al. argued that in living donor liver transplantation, it is very important to accurately assess the liver volume as well as to delineate the resection plane (Ikegami and Maehara 2013). If the liver volume of the donor is overestimated, it may lead to postoperative “small liver syndrome.” When deviation from the pre-resection plane occurs during hepatectomy, it may result in a smaller graft from the donor liver that is expected to be transplanted; or damage to the remaining liver tissue of the donor liver may increase postoperative complications. The transparent 3D printed model of the liver can easily, during the operation, solve the above problems due to the opacity of the liver, and the invisibility of the blood vessels and bile ducts within the liver. Moreover, 3D printing of liver can also reduce the loss of liver tissue of potential donors in pediatric liver transplantation; by printing the abdominal cavity of the recipient, it is possible to assess whether the graft is suitable for the abdominal cavity, thereby reducing the “large liver syndrome” in pediatric liver transplantation. Therefore, the occurrence of vascular complications (such as portal vein thrombosis, hepatic artery thrombosis, and hepatic vein stenosis) caused by this syndrome can be decreased, and prognosis can be improved. With the advancement of medical 3D printing technology, the 3D printed liver model can be used to accurately assess the liver volume and visualize the accurate anatomical location of the liver, which is conducive to pediatric living donor liver transplantation.

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5.3.2 A  pplication of 3D Printing in Biliary Diseases 5.3.2.1 In Cholangiocarcinoma Surgery In general, radical hepatectomy is currently the main treatment method for biliary malignancies such as intrahepatic cholangiocarcinoma and hilar cholangiocarcinoma. Accurate intraoperative location of hepatic vascular structure (hepatic vein and portal vein tree), bile duct structure, and tumor lesions is very important, because the operation planning and real-time surgical resection process are dependent on the spatial relationship of these important anatomical structures. The diagnosis and treatment of hilar cholangiocarcinoma is a difficult point in biliary surgery. The application of 3D printing technology provides strong support for the implementation of surgical scientific planning and accurate intraoperative surgery. For patients with hilar cholangiocarcinoma who need right hemi-hepatectomy/ extended right hemi-hepatectomy, partial hepatic artery or portal vein resection, or vascular reconstruction, 3D printing (Fig.  5.8) on the basis of 3D visualization research and analysis is very helpful. The Bismuth-Corlette typing of hilar cholangiocarcinoma can be analyzed by omnidirectional and multi-angle observation of the 3D printed model, including the anatomical course and variation of hepatic vessels and bile duct trees, the location and size of tumor lesions and their relationship with important vascular structures. It is helpful to systematically reflect the anatomical location of the tumor in the biliary tract system and analyze the infiltration of the tumor into the surrounding structures (especially the vascular results). This is conducive to preoperative judgment of the resectability of the tumor and is also helpful for the selection of individual surgical methods. 3D printing techniques can guide accurate anatomical hepatectomy or periportal hepatectomy of hilar cholangiocarcinoma, reduce operation time and the incidence of postoperative complications. 5.3.2.2 In Complex Surgery for Hepatolithiasis With the advancement and popularization of imaging technology and the improvement of hepatobiliary surgery techniques, the overall diagnosis and treatment of hepatolithiasis have been greatly improved, and the residual stone rate after surgery has been significantly reduced. However, the diagnosis and treatment of complex hepatolithiasis have always been a difficult and contentious issue in biliary surgery, and it remains a great challenge to deal with. There is still no unified concept for complex hepatolithiasis. Lau et  al. (2017) proposed that complex hepatolithiasis mainly includes the following types: • One or more bile duct surgeries have been performed due to bile duct stones, but reoperation is required because of

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

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Fig. 5.8  Front view of 3D printed model of hilar cholangiocarcinoma. Note: Red for the celiac artery system, dark for the hepatic vein system, light blue for the portal vein system, yellow for the dilated bile duct, and brown for the hilar bile duct tumor

•

• • • •

residual stones, recurrence, or recurrent cholangitis episodes. Reoperation is needed because of inappropriate biliary tract surgery performed in the past, such as various biliary anastomoses. Stones are distributed on both sides of the liver. Stones combined with high stenosis or Caroli disease. Stones associated with biliary cirrhosis and portal hypertension. Stones associated with cholangiocarcinoma.

The lack of accurate diagnosis and reasonable treatment may lead to repeated operations of patients. Repeated operations may result in biliary cirrhosis, end-stage biliary disease, or eventually cholangiocarcinoma, seriously affecting the quality of life and survival of patients. For patients with complex hepatolithiasis, the location of stones, the course and variation of bile ducts, and the anatomic relationship between blood vessels and bile duct can be clearly displayed by 3D printing, which is helpful to analyze which surgical treatment is most scientific. The 3D printed intrahepatic duct model can help to observe the spatial relationship between intrahepatic anatomy, lesions, and intrahepatic vessels and/or bile ducts from multiple angles to ensure the feasibility, accuracy, and controllability of the operation. The liver 3D printing model, which faithfully displays the spatial relationship between the stones and the liver vessels, is brought into the operating room. Under the real-time indirect navigation of 3D models, the operation can be carried out smoothly.

Zheng et al. (2017) showed that among 42 cases of complex hepatolithiasis, 24 cases underwent 3D printing assisted surgery, and 28 cases underwent conventional CT imaging assisted surgery. The former was superior to the latter in terms of operation time, intraoperative bleeding volume, residual rate of immediate calculi, final residual rate, and complication rate. Their study indicated that 3D printing technology leads to shortened operation time, reduced blood loss, reduced incidence of complications, and accelerated recovery of patients. In recent years, Professor Fang Chihua’s team has applied 3D reconstructed models and 3D physical printed models to the clinical diagnosis and treatment of hepatolithiasis, constructed a 3D diagnosis and treatment platform for hepatolithiasis, and achieved digital anatomy, diagnostic programming, and visualization of minimally invasive surgery for hepatolithiasis (Fang et al. 2015). Their protocols have the following advantages: • Accurate location of stones accurately and reduction of repetitive operations for patients with complex biliary structures. For the treatment of diffuse hepatolithiasis, hard stone lithotripsy can improve the rate of hepatectomy with a single operation. • Determination of the surgical resection plane during hepatectomy; which is helpful for indirect navigation for the separation of important vessels and the entire resection of hepatolithiasis and diseased bile ducts, so as to: reduce/ avoid injury of important anatomical structures, reduce the risks of surgery, reduce surgical complications, and improve prognosis.

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b

Fig. 5.9 (a, b) 3D printed models of complex hepatolithiasis; front view. Note: Red for the celiac artery system, dark blue for the hepatic vein system, green for the dilated bile duct, light blue for the portal vein system, and white for hepatolithiasis

Professor Fang Chihua’s team used 3D printed models to guide the operation of complicated hepatolithiasis, which has achieved good short-term results (Fig. 5.9).

5.3.3 A  pplication of 3D Printing in Pancreatic Surgery Pancreatic cancer is a refractory malignant tumor of the digestive system, with hidden onset, difficult early diagnosis, rapid progress, and poor prognosis. The 5-year survival rate is ≤6% (Jemal et al. 2010). Pancreatic surgery is challenging in modern surgery, not only because of the structural characteristics of the pancreas itself, but also the structural relationship of the pancreas and its surrounding structures including the duodenum, common bile duct, portal vein, superior mesenteric artery, superior mesenteric vein, and celiac trunk artery. Therefore, to evaluate the feasibility of the operation, devise the surgical plan scientifically, make and implement accurate surgical treatment; it is very important to analyze the normal anatomy and variation of the patients before operating. Through 3D printed pancreas, the relationship between pancreatic tumors and structures such as peripancreatic vessels can be truthfully demonstrated, so that the operators can clearly and intuitively understand the anatomy of the key sites and perform the surgical operations accurately. This will result in shortened operation time, reduced blood loss, and reduced incidence of intraoperative complications.

Through 3D printing, the preoperative analysis of a 3D physical model of the pancreas is helpful to further understand the patient’s condition; moreover, 3D printed models can help patients and their relatives understand the complexity of the lesion and the risk of surgery. By using these models, surgeons can perform preoperative planning and outcome prediction for patients under a simulated environment approximate to the real world. 3D printing technology can provide accurate data and rich information for the actual clinical surgery, reduce intraoperative bleeding, shorten operation time, reduce complications, and lower risks. 3D visualization for pancreatic head carcinoma plays an important role in accurate preoperative diagnosis, resectability assessment, and individualized surgical planning. 3D printing of the pancreas can help to realize a leap-forward transformation from a 3D visualization image to the physical model, so as to better guide accurate surgery of complex pancreatic head tumor. The advantages of pancreatic 3D physical model printing: In the cases of complex pancreas and ampullary tumors with close relationship between tumor and portal vein, as well as superior mesenteric vein and superior mesenteric artery, 3D visualization of pancreas was performed after obtaining 3D visual data, and then intraoperative indirect navigation was performed to ensure the smooth implementation of the operation. Dr. Xiang Nan et al. performed a 3D physical printing model on complex pancreatic head and periampullary tumors (Xiang 2016). By observing the 3D model, the following information can be accurately and comprehensively diagnosed:

5  Application of 3D Printing Technology in Hepato-Biliary-Pancreatic Surgery

• The shape and location of the tumor. • The location and degree of expansion of the bile duct and pancreatic duct obstruction. • The morphological change of the pancreas. • The spatial relationship between the tumor and the surrounding large blood vessels. These factors are helpful to assess the resectability of the tumor and determine the surgical resection plane. The 3D printed model of the pancreas was brought into the operation a

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room and compared with actual surgery in real time. By continuously adjusting, the 3D printed model can be placed into the best anatomical position and can provide intuitive indirect navigation and guide key surgical procedures. It also confirms that a 3D printed pancreas can help to accurately locate lesions, quickly identify key anatomical sites, and contribute to successful completion of complex pancreas surgery (Figs. 5.10 and 5.11). The application of 3D printing technology in preoperative planning and indirect navigation during operation, can improve the safety of surgery, reduce

b

Fig. 5.10  3D printed physical model of pancreatic tumor. (a) Front view; (b) back view. Note: Brown for the pancreatic head tumor and light blue is the portal venous system

a

Fig. 5.11  3D printed physical model of ampullary tumor. (a) Front view; (b) back view. Note: Gray for the ampullary tumor, brown for the enlarged lymph nodes, light blue for the portal venous system, green for

b

the dilated bile duct system, red for the celiac artery system, and white for the stent

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intraoperative inadvertent injury, reduce postoperative complications associated with pancreatic cancer surgery, and thus contribute to better postoperative recovery. These virtues are in harmony with the concept of enhanced recovery from hepatobiliary and pancreatic surgery. The 3D print of the pancreas can better assist the preoperative evaluation and planning of pancreatic cancer surgery and help to improve the safety of surgery. However, as a relatively new technology in clinical applications, 3D printing technology for pancreas surgery requires a large number of clinical data and further large randomized controlled trials to verify its effects.

5.3.4 Prospects Along with the research and development of biomaterials and 3D printing technology, the efficiency of 3D printing for hepatobiliary and pancreatic diseases will be greatly improved, and the cost will be reduced simultaneously. Also, rapid and high-fidelity 3D printing will be available for other parts of the human body. Through formulating innovative solutions to old problems, a new canvas is provided for innovative thinkers to write new chapters of modern surgery. Revolution in 3D printing technology has touched upon surgery; printing and transplanting the entire organ may become ordinary one day in the future. Lipson, the famous robot engineer pointed out optimistically that 3D printing will bring forth a revolution in the medical field. Since the mapping of the human genome, personalized medicine is coming. Personalized 3D printing is playing an increasingly important role, from nutrition deployment to prosthetic equipment and medical implant production. More areas being impacted by this technological revolution include biological printing equipment, surgical operation training, and even printing of the precise drug dosage requirements customized to individual patients. This technology can also influence and penetrate into the clinical diagnosis and treatment in many ways (Lipson 2013). The application of 3D printing technology in hepatobiliary and pancreatic surgery is still in early development, and more research is needed. We firmly believe that the use of this technology will be expanded in the future and will enhance the diagnosis and treatment of hepatobiliary and pancreatic surgery disease, so that more patients will benefit and truly enjoy the higher quality of life brought by scientific and technological developments.

C. Fang and Z. Fang

References Bagaria V, Bhansali R, Pawar P. 3D printing- creating a blueprint for the future of orthopedics: current concept review and the road ahead! J Clin Orthop Trauma. 2018;9(3):207–12. Cho A, Okazumi S, Miyazawa Y, et  al. Proposal for a reclassification of liver based anatomy on portal ramifications. Am J Surg. 2005;189(2):195–9. https://doi.org/10.1016/j.amjsurg.2004.04.014. Fan H, Fu J, Li X, Pei Y, Li X, Pei G, Guo Z. Implantation of customized 3-D printed titanium prosthesis in limb salvage surgery: a case series and review of the literature. World J Surg Oncol. 2015;13:308. https://doi.org/10.1186/s12957-­015-­0723-­2. Fang C, Fang Z, Cai W, et  al. Establishment and value of three-­ dimensional visualization diagnosis platform in the treatment hepatolithiasis. Chin J Pract Surg. 2015;35(9):974–8. Igami T, Nakamura Y, Hirose T, et  al. Application of a three-dimensional print of a liver in hepatectomy for small tumors invisible by intraoperative ultrasonography: preliminary experience. World J Surg. 2014;38(12):3163–6. Ikegami T, Maehara Y. Transplantation: 3D printing of the liver in living donor liver transplantation. Nat Rev Gastroenterol Hepatol. 2013;10(12):697–8. Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010. CA Cancer J Clin. 2010;60:277–300. Kodama H.  Automatic method for fabricating a three-dimensional plastic model with photo hardening polymer. Rev Sci Instrum. 1981;52:1770–3. Kuroda S, Kobayashi T, Ohdan H. 3D printing model of the intrahepatic vessels for navigation during anatomical resection of hepatocellular carcinoma. Int J Surg Case Rep. 2017;41:219–22. https://doi. org/10.1016/j.ijscr.2017.10.015. Lau WY, Zhang S, Jiang H, et al. Expert consensus on accurate diagnosis and treatment of hepatolithiasis by 3D visualization. Chin J Pract Surg. 2017;37(01):60–6. Lipson H. New world of 3-D printing offers “completely new ways of thinking”: Q&A with author, engineer, and 3-D printing expert Hod Lipson. IEEE Pulse. 2013;4(6):12–4. Nakagawa T, et al. Blanking tool by stacked bainite steel plates, Press Technique, 93–101; 1979. Swainson WK.  Method, medium and apparatus for producing three-­ dimensional figure product. US Patent 4,041,476; 1977. Ventola CL. Medical applications for 3D printing: current and projected uses. P & T. 2014;39(10):704–11. Xiang N. The establishment and clinical application of diagnosis and treatment platform based on three-dimensional visualization of pancreatic head and periampullary neoplasms: Southern Medical University; 2016. Xiang N, Fang C, Fan Y, et al. Application of liver three-dimensional printing in hepatectomy for complex massive hepatocarcinoma with rare variations of portal vein: preliminary experience. Int J Clin Exp Med. 2015;8(10):18873–8. Yamazaki S, Takayama T.  Current topics in liver surgery. Ann Gastroenterol Surg. 2019;3(2):146–59. https://doi.org/10.1002/ ags3.12233. Zein NN, Hanouneh IA, Bishop PD, et al. Three- dimensional print of a liver for preoperative planning in living donor liver transplantation. Liver Transpl. 2013;19(12):1304–10. Zheng C, Gao H, Bao H, et al. Application value of 3D print technology in the hepatolith complicated disease. Syst Med. 2017;2(06):52–4.

6

Virtual Surgical Instruments and Surgical Simulation Susu Bao, Jiahui Pan, Xu Chang, Dongbo Wu, and Chihua Fang

6.1

Introduction

Rapid advances in modern biliary surgery are inseparable from the evolution of science and technology and their applications in medicine. In recent years, computer technology has been increasingly applied in the field of modern medicine with the continuous advance of computer technology and medical imaging technologies such as CT and MRI. Unfortunately, these medical imaging devices can only provide a two-dimensional (2D) grayscale image of the human body. Physicians can only estimate by experience the size and shape of the lesions as well as the number and location of the stones based on multiple 2D images, and then “conceive” the 3D geometric relationship between the lesions and the surrounding tissues. This poses great challenges to the diagnosis and management of biliary diseases. Moreover, because of the complexity and variability of the structure of the liver and biliary tract, the unclear intraoperative definition of the diseased area is a key issue, with the potential for massive bleeding and postoperative complications. With the realization of the complexity and variability of the internal piping structure of the hepatobiliary system, hepatobiliary surgery has become recognized as a difficult and important discipline within the field of general surgery. Electronic Supplementary Material The online version of this chapter (https://doi.org/10.1007/978-­981-­33-­6769-­2_6) contains supplementary material, which is available to authorized users. S. Bao · J. Pan South China Normal University, Guangzhou, China X. Chang Panyu District Hospital of Traditional Chinese Medicine, Guangzhou, China D. Wu Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou, China C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China

Many unsolved problems remain, and involve the development of clinical hepatobiliary anatomy, the updating of medical equipment, and the improvement of the surgeon’s surgical skills. Virtual reality (VR), which has been applied, researched, and developed in the medical field in recent years, maybe one of the technical means to solve these problems. VR, which refers to the use of computer technology and hardware devices to realize a virtual illusion that can be experienced through vision, hearing, touch, or smell, includes not only hardware configuration, but also software and hardware coordination and man–machine interfaces. VR has characteristics such as immersion, interaction, and imagination (three Is). VR is a new practical technology involving many disciplines. It integrates advanced computer technology, sensing and measurement technology, simulation technology, and microelectronics technology. In computer technology, it is mainly dependent on computer graphics, artificial intelligence, network technology, man–machine interface technology, and computer simulation technology. The development of these related technologies has led to the progress of VR and also promoted its full application in a series of fields such as education, medicine, entertainment, science and technology, industrial manufacturing, construction, and commerce. The successful development of the National Library of Medicine’s Visible Human Project (VHP) in the United States has opened the door for computer image processing and VR to enter medicine and the project has promoted the application and development of VR in the medical field. Virtual surgical instruments are an essential part of the virtual surgery system. By using virtual surgical instruments with tactile and visual feedback, users can perform various preoperative simulations and operation procedural exercises. There are various surgical instruments in abdominal surgery, such as the scalpel, electric hook, suture needle, surgical scissors, and vascular forceps. The diversity and complexity of the operation for these instruments have a direct impact on

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_6

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the fidelity and real-time capabilities of the virtual surgery system. To provide the operator with a truly immersive operational experience, it is necessary to combine the graphical display with the tactile display of the virtual surgical system. When people interact with the outside environment, they mainly perceive the characteristics of the environment through the sensory channels such as vision, touch, and hearing. The human brain processes the information and gives instructions to the arms to act on the environment. As a surgeon, it is essential to perceive and operate the external environment by hand. In actual surgery, the judgment and operation of the surgeon are mainly dependent on the sense of touch. Tactile sensation is a general term for mechanical stimuli such as contact, sliding, and pressure. Force feedback is a crucial tactile channel that allows the user to perceive the weight of an object and its resistance to force. The close coupling of visual feedback, tactile feedback, and 3D spatial sensation allows the operator to realistically feel the changes and reaction forces generated by the organ tissue during the operation of the virtual surgical instrument. Only in this way can the virtual surgical system be of practical significance. The simulated surgical system in China started relatively late. There is little investment in research of the virtual surgery systems with powered haptic feedback, especially in the simulation of the liver and other soft tissues. For example, the 3-Dimensional Medical Image Processing and Analyzing System (3DMed) developed by the Chinese Academy of Sciences lacks force feedback; the simulation environment is simple, the surgical instruments are not developed, and the procedure is complicated; the clinical surgeon must possess strong computing skills to operate the 3DMed system (Tian et al. 2008). The National Digital Manufacturing Technology Center of Shanghai Jiao Tong University has developed a multifunctional virtual surgical instrument that can operate scalpels, surgical scissors, and surgical forceps, but it does not possess the force feedback function. Only by combining visual feedback and tactile feedback can the operator’s immersion be truly improved, and the utility of virtual surgery be achieved.

6.1.1 Virtual Anatomy The Atlas of Human Anatomy has always been the primary tool for studying and identifying human anatomy. A traditional atlas of human anatomy is mostly illustrations depicted in 3D or pictures of actual anatomical structures. The atlas of digital 3D human anatomy established by the application of virtual reality technology, as a “virtual human” digitized dataset, visualizes the human body structural image information, as obtained by modern medical imaging equipment. It has two advantages: accurate location in space, and compre-

S. Bao et al.

hensive observation, measurement, and study of anatomical structure. Bernard Pflesser and his team at the University Hospital Eppendorf, Hamburg enhanced VOXEL-MAN using VHP datasets (Pflesser et al. 2001). In China, a group led by Professor Fang Chihua used the VCH-F1 liver data to study the virtual liver biliary tract (Fang Chihua et al. 2005). The reconstructed 3D liver model can not only help to observe the target through the enlargement, reduction, and rotation of the stereo image, but also can vary the color and transparency for various tissues to display liver structures individually or in combination.

6.1.2 Surgical Simulation Surgical simulation refers to the simulation of a surgical process on a “virtual human body or organ” using virtual surgical instruments (scalpel, hemostatic forceps, etc.) in a virtual environment on a computer. This technology is also known as computer-assisted/aided surgery (CAS) and image-guided surgery (IGS). Surgical simulation is an essential application of virtual reality in the field of medicine and has become a hot topic in recent years. In order to set up a virtual surgical system, it is necessary to reconstruct the 3D geometric model of human tissues and organs. The physical model, the dynamic model, the deformation model, and the finite element model are constructed using the geometric model with the knowledge of biology and mechanics.

6.1.2.1 Characteristics of VR Surgical Simulation System • Reality Accurate and detailed description of patients’ organs as well as the shape, location, and deformation of the lesion. • Real-time The ability to process data and display results in real time. • Accuracy Accurate description of the internal organ structure. • Manipulation Simulations of organ manipulation by hand or other medical devices in a 3D virtual space, such as pushing, pulling, pressing, and cutting. • Perception Ability to receive and process specific feedback. 6.1.2.2 Significance of Establishing a Surgical Simulation System Preoperative Planning and Rehearsal The system can help to develop surgical planning by using patient examination data. Through continuously targeted rehearsal, the operation plan can be improved to establish the best operation path, so as to reduce unnecessary damage to the healthy tissues. Thus, the accuracy of the operation

6  Virtual Surgical Instruments and Surgical Simulation

l­ocalization ensures an increased success rate and reduction of surgical complications. Moreover, the guidance of the expert surgical system based on expert experience, can be obtained to improve surgical skills. Intraoperative Navigation and Monitoring Surgical robots (such as Aesop and Da Vinci) have been clinically used in surgical operations, especially in neurosurgery and cardiovascular surgery. By using image information provided before surgery such as from X-ray, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Digital Subtraction Angiography (DSA), CT Angiography (CTA), MR Angiography (MRA), and Positron Emission Tomography (PET), as well as medical robots; the real-time images during operation can be registered and located to guide the surgery (such as radiofrequency ablation, interventional therapy, and vascular embolization). It is of great significance for improving the accuracy of surgery, reducing surgical injury, and improving the success rate of surgery. Surgery Teaching and Training With “virtual surgery,” medical students or doctors can learn surgical skills and even practice the procedure without time and space constraints. They can also be guided by an expert operating system based on expert experience to improve surgical skills and shorten the time to competency. Organ Transplantation and Receptor Matching Model Virtual surgery can help surgeons accurately measure the size and shape of organ transplants (such as liver transplantation, especially living donor liver transplantation) before organ transplantation based on a 3D reconstruction of the image data and evaluate the matching degree of their morphology. Improved Doctor–Patient Relationship A large number of doctor–patient relationships are harmed by a lack of communication between doctors and patients, and a lack of in-depth understanding by patients and their families. Virtual surgery can bridge the gap between doctors and patients. With the help of this technology, doctors can easily introduce the patients’ condition, surgical treatment plan, and the procedure of the operation in detail, to achieve an excellent doctor–patient relationship with full mutual understanding and trust. Reduced Surgical Costs Modern surgical testing systems are expensive and costly. Since virtual surgery is not restricted by surgical equipment, it can reduce the blindness of surgical exploration thereby reducing the degree of bodily injury; consequently, shorten-

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ing the recovery cycle of patients, and reducing the expense to patients and hospitals. Construction of Customized Prosthetic Fitting Models Virtual surgery can design implants (prostheses). For example, a computer can help doctors accurately measure the size and shape of a hip bone using non-destructive 3D imaging prior to the hip replacement surgery, and customize the prosthetic implants, which can significantly reduce the proportion of reoperation due to size failure. Remote Intervention Virtual surgery and remote intervention will enable surgeons in the operating room to get interactive consultations with remote experts in real time. The interactive tools allow the consultant to project the target on the patient to help guide the surgeon’s operation or to help manipulate the instrument through remote control. With remote intervention the skills of experts can be accessed regardless of space or distance.

6.1.2.3 Current Status of Surgical Simulation The rapid development of modern surgery is closely related to the application of modern scientific and technological means in medicine. Höhne et  al. (2001) reconstructed the human body model utilizing data from the Visible Human Project (VHP) dataset, and then, they operated on the reconstructed model with a simulated scalpel; “real” visual and tactile effects were produced using the particular device PHANTOM. The virtual intracranial visualization and navigation system developed by Kockro et al. (2000) used a virtual environment constructed by 3D reconstruction of patients’ imaging data obtained before operation (CT, MRI, MRA) to plan and simulate the operation of brain tumor and intracranial vascular malformation. Soler et al. (2000) used interactive visualization and virtual cutting tools to perform virtual hepatectomy on the 3D HCT (spiral CT) liver model according to the user-defined cutting plane. All of these protocols significantly improved the surgical effect. With the continuous progress of computer technology and image processing technology, simulation reality technology has become a rapidly developing technical field in recent years, with increasingly broad application. Virtual simulation technology has been widely used in biliary diseases such as hilar cholangiocarcinoma, ampullary tumor, extrahepatic cholecystolithiasis, choledocholithotomy, individualized cholecystolithiasis and choledocholithotomy, and left hepatectomy. Surgeons can make full use of simulated surgery to practice repeatedly, familiarize themselves with the surgical process, improve surgical skills, and shorten their time to competency. They can also use it to carry out new operations and to update the existing knowledge of operations and strive for excellence.

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6.2

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Virtual Surgical Instruments

Surgical simulation refers to the use of a variety of medical image data and virtual reality technology to create a simulation environment on a computer. Surgeons use the information in the virtual environment to perform surgical planning and training and to guide the actual operation. During the virtual surgery process, the cutting tools and the surgical instruments are needed for operation simulation, such as surgical scissors, hemostatic forceps, and suture. The PHANTOM from SensAble Technologies are used to provide an excellent graphical user interface, and various kinds of virtual surgical instruments are developed in combination with GHOST SDK, a 3D interactive tactile environment development kit of PHANTOM. After importing the reconstructed STL file, the 3D objects of the bile duct, artery, and vein were obtained and combined to simulate the operation of incision and suture.

6.2.1 Geometric Modeling The geometric model of the liver is obtained from the previous 3D reconstruction and imported into the virtual surgical platform through program reading. The STL model is a geometric model with a triangular set to represent the shape of the outer contour of the object. In the tactile frame of GHOST SDK, the model is transformed into the triangular mesh model required by GHOST SDK by programming. In order to speed up the calculation of collision response and to integrate the computational force feedback algorithm (developed in-house), it is necessary to initialize the topological information of the 3D model, that is, to complete some calculation work when the program is initialized. Then the necessary information is called directly during the movement of the virtual surgical instruments to establish an indexed triangle mesh.

In the indexed triangle mesh, we maintain two lists: the vertices and triangles. Each vertex contains a 3D position, as well as additional information about its geometric attributes (colors and textures) and physical characteristics (hardness and friction coefficient) to facilitate real-time extraction in an interactive simulation. Each triangle points to its three vertices. These vertices are listed in counterclockwise order, and the surface normal vector should be precalculated. Compared with triangular arrays, the use of indexed triangular mesh has the following advantages: • Space-efficient. Its integer vertex index is much smaller than the vertex repetition rate in a triangular array. • Implicit adjacent topology information. Although the side information is not directly stored, the public side can be found by searching the triangle table. Reference to the actual surgical instruments, geometric modeling of surgical instruments was performed by using the Open Graphics Library (OpenGL) software development kit and 3D graphics software. Surgical instruments cannot be simply constructed by basic elements supported by OpenGL, and the use of 3DMAX improves the realism of model rendering. 3D geometries are exported into 3D Studio (3DS) format by 3DMAX. Finally, by using OpenGL for graphics programming, the 3DS format model is generated into an OpenGL display list and thus improve OpenGL performance (Fig. 6.1)

6.2.2 Motion Modeling Virtual surgical instruments are introduced into the reconstructed 3D object to perform various surgical procedures including cutting, dissecting, and clamping. 3D objects in the simulation system consist of two categories: one is 3D objects with a tactile interface, such as virtual surgical instruments; the other is common 3D objects that constitute the

a

Fig. 6.1  Instruments constructed by 3D Studio MAX. (a) Scalpel; (b) Scissors

b

6  Virtual Surgical Instruments and Surgical Simulation

virtual scene, such as abdominal viscera and biliary tissue. For the latter, the geometric transformation functions that are available in OpenGL can be applied for coordinate transformations such as translation and rotation. A tree structure is used to describe the hierarchical nature of the objects. The exposed triangles of the liver and its internal vessels correFig. 6.2  Motion modelling. (a) Simulated liver; (b) hepatic vein incision; (c) Suture of hepatic veins

a a

b b

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spond to the leaf nodes of the tree. These triangles specify the geometrical properties of leaf nodes and their direction and proportion relative to the parent node. Any transformation applied to the parent node will automatically affect its leaf nodes. The motion of all objects is constrained and controlled in this way (Fig. 6.2).

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c

The PHANTOM interface corresponding to the virtual surgical instruments is a particular type of 3D object. In the servo loop, the status information of the PHANTOM device (such as position and orientation) can be queried by the callback function. The orientation of the PHANTOM stylus is described by a 4×4 homogeneous coordinate transformation matrix. In addition, the motion modeling of virtual surgical instruments also needs graphics and PHANTOM correction. In the 3D simulation, the view of the virtual camera and workspace of PHANOM should be aligned to immerse the user who participates in the virtual surgery. Therefore, the workspace of PHANTOM needs to be centered on the Z-axis of the visual body. PHANTOM’s workspace should be located between the clipping planes of the observation cone so that objects of interest can appear on the screen. This is achieved by placing the PHANTOM workspace in the center of the virtual camera and moving it along Z-axis. In order to be able to move the surgical instruments within the screen area to the graphical objects mapped to PHANTOM.  It is also necessary to calculate the scaling factor of the PHANTOM working scope.

6.2.3 Physical Modeling Collision detection has been the focus and one of the fundamental problems in surgical simulation. Only when surgical instruments collide with human tissues, is it necessary to perform cutting and suturing procedures. Since the model of organs and tissues is required to be as elaborate as possible, the number of triangles generally reaches 10,000 to 100,000. In order to improve the detection efficiency, a point-to-body collision detection method is used. The particles represent the moving virtual surgical instrument, and triangles represent the static organ and tissues. The virtual surgical instrument (PHANTOM lever) is in contact with the virtual object only at the tip of the stylus, and from this point, the force is fed back to the user’s hand through the operating lever. The specific description is as follows: judge whether the tip of the stylus passes through the object in the scenario according to the motion information of the PHANTOM handle. If intersection is determined, the feedback force can be further calculated based on the point of intersection with the object. The movement of the handle is usually small, relative to the frequency of the tactile feed-

6  Virtual Surgical Instruments and Surgical Simulation

137 Original position

Surface damping

spring

New position

Grid-based operation

Fig. 6.3  Grid-based needle operation

back, which means that each frame only needs to check a relatively small spatial area. In the accurate collision detection phase, the built-in algorithm of the development kit can be used to determine whether the tip of the surgical instrument has collided. For specific collision information (such as the triangle index of the collision and its vertex), the calculation is simplified by the method of vertex/triangle collision. In the actual operation, surgeons usually adopt a variety of surgical instruments for collaborative operation, and hence the collision detection between surgical instruments is essential. Since the model of various surgical instruments are relatively simple, and they do not deform during operation. In order to improve the authenticity of such detection, a free 3D collision detection library (ColDet) is used to achieve body-to-body collision detection (Fig. 6.3). When the surgeon manipulates the surgical instrument to interact with the 3D object surface, a reaction force is felt at collision. PHANTOM’s particle-spring-damper force feedback model can be used for liver physics simulation. Springs and dampers are attached to the surface of the soft tissue. In a virtual environment, a vertex of a virtual surgical instrument model will undergo elastic deformation once it collides with the surface. By obtaining a vector of the original position and the new position of a vertex of the instrument model, the intersection contact point (SCP) of the soft tissue surface can be obtained, and the length of the spring stretching can also be obtained to calculate the surface elasticity (Fig. 6.4). Foreign virtual surgery systems are expensive. However, there is no medical image processing and virtual surgery system for abdominal and thoracic surgery in China, and no simulation environment is provided. The simulation system has only partial functionality for force feedback and does not provide a realistic simulation of the operating environment. Also, the production of viscera and visceral surgical software involves a considerable amount of data and calculations. The

Fig. 6.4  Diagram of force feedback model

methods to achieve the rapid reconstruction, arbitrary cutting, soft tissue deformation, and the software development and hardware configuration of human–computer interaction of the existing methods remain as problems to be solved.

6.3

Surgical Simulation

With the interdisciplinary integration and rapid development of computer technology, image processing technology, medical physics, and medicine; the methods of surgical diagnosis and treatment are undergoing rapid changes. The computed-­ aided surgery system and the simulation surgery system devised in recent years are the results of the rapid development and application of information science in the medical field. Simulated surgery refers to the application of virtual human research results on the “virtual human” surgery by using simulated surgical instruments (scalpels, hemostats) in the virtual surgery environment. Surgeons can use these advanced technical means as the preoperative, intraoperative, and postoperative auxiliary support for real surgery to make the surgery safer, more reliable, more accurate, and less invasive. Current research on simulation surgery mainly focuses on neurosurgery, plastic surgery, and orthopedics; especially in intraoperative navigation, which combines virtual reality with augmented reality; and even the successful application of surgical robots in clinical practice. However, there are few clinical reports in the field of hepatobiliary and pancreatic surgery, which are limited to the preoperative study or evaluation of liver surgery. For example, Bro-Nielsen et al. used liver data from the VHP male dataset to study the reconstruction of the liver and simulate the surgical plane of the liver by finite element method (Bro-Nielsen et  al. 1996). They believed that the 3D reconstruction of the liver contributes to the understanding of the liver anatomy, and it is possible to realize the preoperative planning, training, and teaching of

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liver surgery. Wigmore et al. used 3D models reconstructed from computed tomography angioportography (CTAP) images in clearly displaying the hepatic and portal veins. Twenty-seven patients undergoing hepatobiliary surgery were retrospectively studied. By comparing tumor volume, total liver volume, and functional liver volume to body weight, it was found that functional liver volume was strongly correlated to body weight, and the risk of postoperative liver failure could be well predicted (Wigmore et  al. 2001). At present, liver surgery remains one of the most challenging operations, mainly because of the complexity and variability of the internal organ structure. Therefore, the establishment of the liver surgery program often depends on the operator’s precise understanding of the 3D spatial relationship between the intrahepatic vascular biliary tree and the lesion. However, anatomical variation and deformity, tumor extrusion infiltration, and previous liver resection can cause changes in the spatial relationship of the intrahepatic biliary vascular tree; so, it is often challenging to develop accurate surgical plans. It is also difficult to accurately determine the variation type, branch direction, location, size, and geometry of the lesion and the spatial relationship between the lesion and the surrounding ductal system by observing the traditional 2D image. Moreover, since visible light cannot penetrate human tissues and the internal structures that have not yet been cut cannot be seen and felt, it is difficult to obtain the spatial information of the individual anatomical structure of the patient’s liver. Due to the lack of a quantitative description of the tissues involved in the operation, intraoperative exploration combined with traditional 2D images cannot adequately meet the needs of liver surgery. Doctors can only rely on experience to plan for liver surgery blindly, which inevitably leads to inaccuracy in the location of the operation space. Moreover, it is impossible to accurately formulate the operation path and avoid the risks of surgery, which will undoubtedly affect the quality, increase trauma, and prolong the duration of surgery. Meanwhile, because 2D images cannot accurately calculate the liver volume, and for patients with varying degrees of liver cirrhosis, it is difficult to choose between preserving enough residual liver volume and completely removing the lesion. The rapid development of modern medical image technology and computer technology, especially the appearance of 3D image visualization reconstruction technology, provides an opportunity to solve the above problems. 3D image visualization reconstruction technology is called non-injurious stereoscopic anatomy technology. Its principle is to use computer image processing technology to analyze and process traditional 2D slice images, to realize 3D reconstruction and display of the segmentation and extraction of human organs, soft tissues, and

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lesions, to simplify the cognitive process of the human brain on 2D images, to further intuitively and accurately display the full range of stereo information of the liver and its piping systems and lesions. The 3D image visualization reconstruction technology can assist the physician to analyze the lesions and other areas of interest qualitatively and quantitatively, which significantly improves the accuracy and reliability of medical diagnosis. It can provide accurate, individualized anatomical information for the design of the surgical plan, so it has a more significant clinical application value than traditional two-dimensional tomography. On the other hand, although the emergence of the 3D digital model of the liver has dramatically deepened the surgeon’s understanding of liver anatomy as well as the spatial relationship between lesions and intrahepatic ducts, pancreas and peripancreatic tissues, the clinical expectation of hepatobiliary and pancreatic surgery is to develop a comprehensive simulation system suitable for clinical needs. Hepatobiliary and pancreatic surgeons can use it to practice repeatedly, familiarize themselves with the surgical procedures, improve surgical skills, and shorten time to competency. It can also be used to carry out new operations and to learn from the old and improve the operation, reduce the trauma of the operation, preserve the function of the liver, and improve patients’ quality of life after the operation. The surgical simulation system requires that the target object model and the simulated surgical instrument must have both high-quality realistic visual images, and real-time interaction of high-resolution, Life-like haptic feedback (force feedback). The visual feedback refers to observing the realistic virtual environment through the display and the real-time deformation of the simulated body under the operation of the interactive device; the tactile feedback means that the operator perceives the physical characteristics of the simulated body through the interactive device. Fidelity refers to the degree of the recreation of the whole structure and behavior of the simulation object and the capacity of the system simulation object. In the visual simulation surgery system, in order to ensure a real-time experience from the simulation process, the graphics refresh frequency of no less than 30 Hz is required, and the force feedback refresh frequency is not less than 1000 Hz. Tactile feedback is a two-­ way exchange of information with the user, while the visual feedback is one way. When the user exerts an external force on the virtual model, the data is transmitted to the interface controller. The master computer calls the graph drawing software to change the virtual environment and relay the positional and tactile feedback information to the user. Any virtual reality system is restricted by its temporal and structural authenticity, which is mainly determined by its hardware structure and software composition.

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6.3.1 The Hardware System Hardware devices include the main computer graphics workstation, display device, and the PHANTOM Force feedback device. The computing requirements to run the PHANTOM device are a computer with at least a 2 core 2 GHz processor, 2 GB available RAM, 512 MB Hard drive, and a high-speed connection (IEEE 1394a firewire). it mainly completes the tasks of simulation calculation and graphics rendering. Of the two tasks, the simulation calculation involves the display of virtual environment, collision detection, force feedback calculation, and tactile interaction. The display equipment mainly completes visual feedback between the operator and the virtual environment. The PHANTOM Force feedback device is an essential tool for users to interact with simulation systems. Through PHANTOM, the space position and motion direction of “surgical instruments” (force feedback device joystick) controlled by the operator can be input into the system. At the same time, after the host computer completes collision detection and forces feedback calculation, tactile feedback is provided to the operator by PHANTOM, so that the surgeon can perceive the delicate features of the object and the resistance of the object to the force. The product “PHANTOM” with a 3D force feedback function developed by SensAble Company, is used as a tactile interactive device, and the model is PHANTOM Desktop. The PHANTOM product, developed at the Massachusetts Institute of Technology in the United States, has filed several patents. Among them, PHANTOM Desktop provides a real-

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istic 3D force feedback function for users with its first-class design. Moreover, the device’s universal design makes it compatible with operating systems running on ordinary microcomputers. This interactive device is different from the previous tactile device. Its portable design and compact base bring flexibility for users and avoids the disadvantages of the traditional device, such as large volume, skeleton mechanical structure, noise, and joystick vibration in the tactile device. In terms of design, due to sufficient consideration of the general working application environment, this type of equipment is connected to the computer through extended parallel port (EPP) and is equipped with a general 110/220v AC power supply (Fig. 6.5). The accepted criteria for measuring the quality of a tactile feedback device are low inertia, low lag, high reverse drive capability, extensive force range, high mechanical signal bandwidth, and suitable workspace. PHANTOM Desktop is a 6-DOF force feedback manipulator with joint coordinates, which can send instruction information to six directions of rotation and can also feedback the force information to X, Y, and Z directions. In other words, the user can perceive and manipulate the 3D simulation body built in the virtual environment through the joystick or finger sleeve of the PHANTOM end, and feedback tactile information to users. Its fundamental performance indicators and relevant parameters are shown in Table 6.1, which can fully meet the needs of tactile interaction in virtual abdominal surgery.

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Fig. 6.5  The hardware system of surgery simulation. (a) Computer host; (b) display of the simulation system; (c) PHANTOM (the force feedback device) Table 6.1  Parameters of PHANTOM Resolution 0.023 mm

Maximum force 7.9 N

Rigidity 3.16 N/mm

Force feedback x, y, z

Stylus inertia 45 g

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6.3.2 Software System The software system is the core of the surgical simulation system. Through this system, various types of surgical simulations are available, and feedback can be provided according to the simulation results. All calculations related to visual and tactile feedback can be completed by the software system. By using a tactile development kit that is compatible with PHANTOM (Fig. 6.6), a virtual tactile environment can be easily established. The software development environment is the Visual C ++ platform. The design languages and the development kit of the virtual environment mainly include OpenGL, GHOST, and OpenHaptics SDKs.

6.3.2.1 FreeForm Modeling System FreeForm Modeling System is a force feedback virtual reality system developed by SensAble Technologies, Inc. The system can be used in conjunction with PHANTOM. Although the FreeForm system is powerful and can simulate the virtual liver surgery after research, it still has some certain drawbacks: • Virtual liver surgery requires not only surgical tools but also instruments such as surgical scissors, vascular forceps, sutures, which are currently not available in the FreeForm system. • FreeForm is not a native virtual surgery system, and its expansibility is limited. Its interface and related functions need to be improved. Professor Fang’s research group has independently built a virtual reality software solution.

6.3.2.2 Open Graphics Library A virtual surgical instrument with high fidelity is designed in the system, this “virtual instrument” can then be manipulated through the PHANTOM handle to simulate the surgical processes, such as liver cutting. Real-time force feedback can be

Fig. 6.6  The liver is being cut with PHANTOM

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generated by real-time cutting and suture of the liver, and the force can be felt concurrently. The Open Graphics Library (OpenGL) is strictly defined as “a software interface to graphics hardware.” In essence, it is a fully portable and fast 3D graphics and modeling library. OpenGL is a software interface that uses specialized graphics processing hardware to support users’ graphics and image manipulation for high-­ quality 3D objects. OpenGL sets patterns, determines the graph element, and describes other OpenGL operations by transferring instruction in the form of functions or procedure calls. The primary work used to create graphics is to organize a finite number of polygons whose objects are composed of vertices in three dimensions. It consists of hundreds of procedures and functions that developers can use to build 3D models and interact in 3D real time. Most OpenGL systems require at least one frame buffer in the graphics hardware system. OpenGL’s graphics functions do not require developers to write 3D object model data into a fixed data format. In this way, developers can not only use their data but also use data sources in other different formats, such as files in 3DS format. This flexibility dramatically saves development time and improves the developmental benefits of the software.

6.3.2.3 Tactile Development Kit General haptics open software toolkit SDK (GHOST SDK) is an object-oriented C++ toolkit, which allows users to define the geometry, physical properties, and tactile effects of emulators according to their needs. OpenHaptics is the successor to the GHOST SDK.  Virtual instruments developed with OpenHaptics are all oriented to PHANTOM force feedback devices, and their programs function well. The OpenHaptics development kit utilizes the OpenGL API, which is very familiar to graphics developers. With the OpenHaptics development kit, developers can use existing OpenGL code to develop special geometric applications, or they can use OpenHaptics commands to set tactile properties of materials, such as friction and hardness. Its extensible architecture allows developers to add support for new shape types. It is also possible to integrate other library files such as physics/kinematics and collision detection engines. The OpenHaptics development kit supports devices ranging from low-cost PHANTOM Omni to larger PHANTOM Premium haptic devices. Software developers can use the SensAble OpenHaptics development kit to add tactile and accurate 3D navigation features in a wide range of areas. The visual simulation surgery system uploads the liver and its internal conduit model reconstructed by MI-3DVS abdominal 3D reconstruction software into the FreeForm Modeling System and uses virtual cutting software and PHANTOM force feedback devices to manipulate virtual surgical instruments to cut, clamp and stitch the liver model. The Visual simulation surgery system is not only an

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excellent liver simulation surgery environment system with immersion, interaction, and force feedback, but also a system that can easily realize the simulation research of all kinds of surgery in other organs of hepatobiliary and pancreatic surgery. At present, this system is being commercialized step by step and has been applied preliminarily in the clinic.

6.3.3 Development and Application of Virtual Surgical Instruments The above-reconstructed model is introduced into the SensAble’s FreeForm 3D Modeling System for necessary modification such as denoising, smoothing, automatic spatial registration, and color matching. The reconstructed image is realistic in shape, and the operator can combine, rotate, set the transparent or opaque display of multiple models, or hide any organs and blood vessels for observation. The smoothed model is observable, and the morphological and spatial anatomical relationship is the same as the real human body. It can meet the requirements of the next auxiliary diagnosis and simulation surgery. Surgical simulation is implemented in a virtual surgical instrument simulation system (software copyright 105,978). The virtual surgical instrument simulation system consists of hardware and software systems. The virtual surgical platform is constructed by using the hardware of the main workstation and force feedback equipment, and the GHOST SDK software development kit used to develop the virtual surgery platform. A complete range of simulated surgical instruments (Fig. 6.7) was made, including scalpel, surgical scissors, hemostatic forceps, needle holder, surgical needle, suture, retractor, bile duct probe, skin forceps, electric knife, ultrasonic knife, and drainage tube.

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function evaluation module to evaluate postoperative liver function, the risk of operation, and the quality of life according to the parameters of the liver function examination; adding the evaluation module of surgical skills to provide a comprehensive evaluation of the skills, process, and the result of the virtual operation. The Liver Visual Simulation Surgery System has the advantages of interoperability, intervention, arbitrariness, and repeatability. It can simulate the cutting process in advance without performing surgery and predict complex and dangerous situations that are expected to occur in actual surgery. For example, when the segmentation level involves important blood vessels or bile ducts in the liver, or there a risk of injury. Under these circumstances, the corresponding adjustment should be adopted. By comparing the advantages and disadvantages of various programs through the simulation of different surgical programs, a reasonable individualized surgical plan is formulated, and necessary preventive measures can be taken in advance. The system not only helps to preserve the integrity of residual hepatic vessels and necessary important structures, minimize the incidence of postoperative complications, and increase the success rate of surgery: but also can accurately measure the total volume of liver, the volume of lesion, the volume of functional liver, the volume of the resection and residual liver; thus predicting the risk of postoperative liver failure. Currently, the liver visualization simulation surgery system only simulates the rough process of liver surgery. However, it has reflected the characteristics of liver surgery, such as preoperative liver resection line, separation of liver tissue, cutting of hepatic vessels, and removal of hepatobiliary tumors and diseased liver. Of course, there are still many vital technical challenges to be solved:

• The recognition of liver internal pipeline structure in liver image is called image segmentation. Due to the unobvious boundary between various duct structures, hepatobiliary tumors, and liver parenchyma in some CT images, the 6.3.4 Significance of Liver Virtual Simulation angiography can only make individual structures stand Surgery out, and the images cannot clearly show all four liver tubes (especially intrahepatic bile ducts) and the adjacent The Liver Visualization Simulation Surgery System is a virrelationship between the tumor and the internal structure tual environment system for hepatectomy based on the self-­ of the liver. Thus, utterly automatic segmentation by the developed 3D system of abdominal medical images software is impossible, and manual intervention is (MI-3DVS) combined with the FreeForm Modeling System. required. Even the effect of manual intervention is not It mainly aims at liver tumor resection simulation, using a completely satisfactory. computer and other techniques to analyze and process two-­ dimensional medical image data; and to provide realistic • The structure of the liver varies. How to apply specific data and a virtual “standard liver” model with image medical images and simulated surgical process and results. It fusion technology to reflect the specificity and individualcan be used to simulate similar resections of other organs, ity of the liver; so as to achieve the preoperative planning such as biliary tract, pancreas, spleen, and other diseases. of specific patients with hepatobiliary tumor, preoperative The results are preliminary, and there is still a lot of work to targeted training, and further improve the surgical plan, be done, such as adding a measurement module to measure increase the success rate of actual surgery and reduce the the volume of the liver and the excised liver, as well as the complications of surgery; remains a problem. size and length of the hepatic duct structure; adding a liver

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Fig. 6.7  Simulated surgical instruments. (a) Simulated scalpel handle; (b) simulated stone forceps; (c) simulated surgical scissors; (d) simulation of needle holder and suture operation; (e) simulated laparoscopic

instruments; (f) simulated electric knife; (g) simulated surgical suture needle; (h) simulated tissue forceps; (i) simulated operating scalpel

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Fig. 6.7 (continued)

• The liver is a highly active organ in the human body. How to combine virtual reality with augmented reality remains a problem. It means valid linking of the “virtual liver” established by the patient’s actual CT scan data, the patient’s human body and the surgical instruments in the laparoscopic surgery or the surgical robot operation; to navigate surgery, reduce injury, improve the success rate, and reduce the complications of the operation. • How to realistically reproduce the scenes and feelings of an actual operation in a virtual operation, is a question that needs to be solved, including vascular injury bleeding, soft tissue deformation, different sensations when the separation of different tissues occur, and a series of force feedback issues such as the different force required to cut different tissues. Clearly, this is a highly technical problem, which needs further research.

6.4

Application of 3D Visualization Virtual Simulation Surgery in Biliary Surgery

The development of modern science and technology is increasingly reflecting the intersection and connectedness of multiple disciplines. Virtual reality (VR) is a high-tech concept developed in recent years. It is an interdisciplinary, integrated technology involving fields such as computer graphics, human–computer interaction technology, sensing technology, artificial intelligence, and cognitive science. It uses the computer to form sensations such as realistic three-­ dimensional visual, auditory and tactile perception, enabling people to experience and communicate with the virtual world through appropriate devices. In the past 10 years, virtual reality technology has exerted an increasingly important

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influence on the medical field with its unique immersiveness, interactivity, visuality, and close integration with modern medicine. It uses specific interactive tools (input devices such as sensor gloves and video eyepieces) to simulate the hardware and software environment in real operation. Users have an immersive sensation during operation. It is widely used in aspects including surgical training, surgical rehearsals, psychology, clinical diagnosis, and telemedicine. Computer-aided surgery (CAS) is realized by combining computer technology, virtual reality technology, medical imaging technology, image processing technology, and robot technology with surgery. It is a new technology based on the ability of computers to process and control large amounts of data at high speed. It provides technical support for surgeons through a virtual operation environment, making surgery safer and more accurate. In recent years, with the development of computer X-ray, CT, MRI, and other diagnostic imaging tools, computers use the image information for 3D image reconstruction, providing objective, accurate, intuitive, and scientific means for surgeons to perform surgical simulation, surgical navigation, surgical positioning, and surgical planning. Surgical support based on this ­three-­dimensional position information, improves the success rate of surgery, reduces complications of the surgery, reduces the trauma of surgery, dramatically reduces surgical wounds, minimizes the physical pain of the patients, and promotes the rapid development of surgical technique.

6.4.1 A  pplication of 3D Reconstruction Technique in Biliary Surgery The development of modern biliary surgery is closely related to the development of science and technology and its application in medicine. Along with the cross-fusion and rapid development of computer technology, image processing technology, medical physics, and medicine; the means, and concept of surgical diagnosis and treatment are changing substantially. In recent years, computer-aided surgical systems and virtual surgery systems have been developed rapidly and applied to the medical field. Surgeons use these advanced technical means preoperatively, intraoperatively, and postoperatively to ensure that surgical operation is safer, more reliable, more accurate, and less traumatic. The complicated pipeline system inside the liver and its physiological and pathological changes determine the difficulty of hepatobiliary surgery. Previous imaging examination has provided 2D plane images. The intrahepatic duct system and its 3D spatial relationship with the tumor could not be shown, and liver volume could not be calculated accurately. Surgeons could only roughly locate the intrahepatic lesion and its related important pipeline structures by image and logical thinking, which served as the basis for the formulation of the

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surgical plan. Therefore, it had certain blindness and unreliability for complex liver surgery. In 1991, Soyer et  al. reported for the first time the successful identification of liver segment and subhepatic segment anatomy with 3D computed tomography arterial portography (CTAP), the display of main portal vein, branches, and their anatomical variation, and the clinical study of preoperative determination of segmental location of hepatic metastases. Their results showed that the accuracy in determining the segmental location of hepatic metastases was 94% for 3D CTAP and 78% for 2D CTAP (1991). Soler et al. (2000) used interactive visualization and virtual cutting tools in 2000. Virtual hepatectomy was performed on the 3D liver model in accordance with the cutting plane developed by the user: therefore, a specific surgical protocol was designed. The operation effect was improved. In 2000, Wolfram Lamadé et  al. (2002) reconstructed the shape of VPH liver by a semiautomatic segmentation method and carried out 2D and 3D reconstruction of four sets of intrahepatic piping systems. The four systems can be integrated with the reconstructed liver to simulate virtual reality liver surgery, reconstructing the main branches of the liver, gallbladder, intrahepatic vein system, and the internal and external bile duct system using a VHP dataset. The model can be used to simulate virtual endoscopic minimally invasive choledochal surgery. Other scholars have successively carried out the 3D reconstruction of hepatobiliary system images, including helical computed tomographic (HCT) cholangiography combined with magnetic resonance cholangiopancreatography(MRCP) technology to show the course of intrahepatic and extrahepatic bile ducts and their pathological changes. 3D HCT reconstruction technique has been used in the diagnosis of biliary diseases; Fang Chihua et al. (2005) reconstructed 3D images of the liver and four canals by CT and MRI scans through hepatic duct perfusion and cast specimens and obtained three-dimensional models of the liver and four canals, which can be used to simulate the operation of virtual hepatectomy. In 2005, Li Kai et al. conducted a 3D reconstruction of the liver, gallbladder, the intrahepatic vessels, and adjacent structures by using a digital visual human dataset, and these reconstructed models were displayed jointly (2005). In the early stage, the liver of cadavers was mainly studied. By using the technique of intrahepatic tube casting technology, the ideal filling agent was selected. On the basis of maintaining the normal anatomical position of the liver, the location, perfusion, embedding, freezing, milling level of the ultrathin sections were carried out. A continuous and accurate cross-sectional dataset of the liver was obtained. The different color thresholds which filled in the hepatic conduits were automatically recognized by the computer, and a 3D digitized visual model of the intrahepatic duct system was established. The complex spatial structure and the adjacent relationship of the intrahepatic conduit were accurately dis-

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played. In recent years, the virtual surgery of three-dimensional reconstruction and liver resection based on 64-slice CT scan data of healthy liver has achieved good results. However, due to the absence of intrahepatic bile duct data from healthy people, 3D reconstruction cannot be conducted. According to clinical practice, the study on reconstruction and virtual surgery of intrahepatic and extrahepatic cholelithiasis using CT data of patients with intrahepatic and extrahepatic bile duct stones are helpful in solving the difficult problems in biliary surgery and promoting development of the science.

6.4.2 S  imulation Surgery for Individualized Intrahepatic and Extrahepatic Bile Duct Stones Cholelithiasis is a common and frequent disease in China and accounts for a significant percentage of the total inpatients in the Department of General Surgery. Hepatolithiasis is primary intrahepatic cholelithiasis. In high incidence areas, hepatolithiasis accounts for the majority of cases. Hepatolithias is characteristically a complicated condition, with a high postoperative residual stone rate, recurrence rate, and complication rate, which can induce cholangiocarcinoma. Additionally, surgical treatment of postoperative residual hepatolithiasis presents a high degree of difficulty. In recent years, with the development of biliary surgery, B-ultrasound, CT, MRCP, choledochoscope, and Endoscopic Retrograde Cholangiopancreatography (ERCP) have been widely used, and the incidence of postoperative residual stones has been significantly reduced. However, postoperative residual or recurrence of stones and other causes requiring reoperation is not uncommon. Preoperative understanding of anatomical abnormalities such as the location of the stone, the number of stones, biliary stenosis, and the formation of cyst is an essential means to prevent residual stones and recurrence after surgery. How to eliminate the hidden dangers of these stones before surgery? In addition to familiarization with the disease, improve the technical level, and improve the equipment conditions, we try to apply novel techniques to the hepatobiliary surgery in order to reduce and eliminate these hazards.

6.4.3 V  isual Simulation Surgery of Cholecystectomy, Choledocholithotomy, and Left Hemi-Hepatectomy In the Freeform, the above model was visually simulated according to the actual surgical procedure. In the established virtual environment system of simulated surgery, the immer-

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sion is intense and the interactivity is good. The force feedback device PHANTOM can be used to control the stereo model at will, including zooming in, zooming out, and omnidirectional rotation. PHANTOM can be used to manipulate the “simulating scalpel” to simulate the process of cholecystectomy, choledocholithotomy, and indwelling T tube. The model performs a single plane cut or arbitrarily cuts, and achieves a “force” feel when cutting, and can also feel the magnitude of force feedback during cutting by adjusting the strength of the cut object. During the simulated operation: the gallbladder was removed; the common hepatic duct was dissected; the stones in the common hepatic duct were removed; the T tube was indwelled; the common bile duct was sutured. The liver was cut from the left side of the inferior vena cava to the left side of the gallbladder notch; the dilated intrahepatic bile duct was dissected; the exposed stones were removed; the proximal bile duct was sutured; the left branch of the hepatic vein was severed and sutured; the right branch of the hepatic vein was severed and sutured; the left half of the liver was removed as a whole; the left part of the liver was transparent, and the residual stones were visible; after the liver was clear, there was no residual stone; the suture of the liver and the common bile duct incision and left hepatectomy was simulated. The simulation operation is close to the actual operation, and the result shows that there is no residue of the stone, and the ideal surgical effect is achieved. According to the actual operation process, the video is entirely smooth, realistic, and close to reality. The liver and each conduit model are imported into the FreeForm Modeling System. For observation, color renderings with distinct differences are given separately (Fig. 6.8). Combined with the partial transparency of the liver surface model, the distribution of the intrahepatic duct structure and the presence or absence of abnormal variation were observed (Fig. 6.9). Cholecystectomy: Activate the gallbladder model and define its force feedback intensity (Fig.  6.10a); using PHANTOM to manipulate the “scalpel” and cut off the gallbladder duct in the neck of the gallbladder according to the actual operation (Fig. 6.10b); using PHANTOM to manipulate the scalpel. Free gallbladder bed (Fig.  6.10c); remove the resected gallbladder (Fig. 6.10d). Choledocholithotomy: Activate the common bile duct model and define the strength of the force feedback (Fig.  6.11a); use PHANTOM to manipulate the “scalpel” and cut the common bile duct in front of the middle of the common bile duct (Fig.  6.11b); activate the stone-cutting forceps (Fig. 6.11c); activate the stones in the common bile duct and remove the stones (Fig. 6.11d). T-tube indwelling: Activate and adjust the position of the T-tube model (Fig. 6.12a); place the T-tube model from the incision of the common bile duct into the longitudinal axis of

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Fig. 6.9  Liver surface model after partial transparency. (a) Front view; (b) back view

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Fig. 6.10  Gallbladder resection. (a) Activate gallbladder and set feedback intensity; (b) cut off the gallbladder neck; (c) mobilize the gallbladder; (d) remove gallbladder

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Fig. 6.11  Choledocholithotomy. (a) Activate the common bile duct; (b) Open the common bile duct; (c) Activate the stone forceps; (d) Activate the stone and remove it

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the bile duct (Fig. 6.12b); use the PHANTOM manipulation of the “suture needle” to stitch the common bile duct at the upper and lower ends of the T-tube (Fig.  6.12c) through rotating the liver surface and transparency of various ducts from different directions. It is clear that all the stones have been removed without residue, and the surgical effect is satisfactory.

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Left hemi-hepatectomy: The liver model was activated and the position was adjusted; the hepatic parenchyma was cut from the left side of the vena cava to the left line of the cholecyst notch; the dilated intrahepatic bile duct was encountered during the incision of the hepatic parenchyma and the dilated bile duct was incised (Fig. 6.13a). Intrahepatic cholelithiasis was removed from the dilated bile duct

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Fig. 6.12  T-tube indwelling. (a) Activate the T tube; (b) Indwell the T tube into the common bile duct; (c) Suture the common bile duct

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Fig. 6.12 (continued)

(Fig.  6.13b); the hepatic vein encountered was severed (Fig. 6.13c); suture of the hepatic vein stump (Fig. 6.13d); continued incision of hepatic parenchyma (Fig. 6.13e); severance of left portal vein branch (Fig. 6.13f); suture the left branch stump of the portal vein (Fig. 6.13g); the right half liver and its conduit were transparent and rotated without residual stones (Fig.  6.13h); residual stones in the intrahepatic bile duct can be seen after the left hepatic duct, and its tube become transparent (Fig.  6.13i); the liver section was sutured (Fig. 6.13j). The remaining right liver was re-rotated after it became transparent and no residual stones were found (Fig. 6.13k).

6.4.4 Discussion As an emerging research direction, simulation surgery is a new cross-disciplinary field combining: medicine, biomechanics, materials science, computer graphics, computer vision, mathematical analysis, mechanical engineering, materials, and robotics. The purpose is to use computer technology (mainly computer graphics and virtual reality) to simulate and guide various processes involved in medical surgery, including preoperative, intraoperative, postoperative procedures. In order to achieve the goal, requires surgical planning, surgical rehearsal, surgical teaching, surgical skills training, intraoperative guided surgery, and postoperative rehabilitation. This study is combined with clinical practice.

The clinicopathological range of intrahepatic cholelithiasis is defined by the pathological range of intrahepatic cholelithiasis, distributed strictly along the bile duct tree, and the many hepatic bile duct strictures. The definition of the clinicopathological range of intrahepatic cholelithiasis is that the pathology is distributed strictly along the bile duct tree, and there are multiple hepatic bile duct strictures. The cholestasis caused by a stricture is the basic factor for the formation and recurrence of the stones. It is also an important factor influencing the effect of surgery. Removal of lesions and stones, elimination of stenosis, unobstructed drainage, and prevention of biliary infection are key to treatment. According to this characteristic, the dilated bile duct and its calculi were reconstructed, and a simulated operation was carried out. The results showed that the location of the dilation and stenosis of the bile duct, as well as the number and location of large stones in the bile duct, were visible. The results of simulated surgery showed that there was no residual stone. This enables the surgeons to have a full understanding of the condition of the stones and biliary tract before surgery and make a surgical plan to deal with the situation during the operation. Stones can be easily removed, and the stricture and dilatation can be properly managed in order to reduce postoperative residual stones and recurrence. The safety of the operation is increased, while the risk and complications of the operation are reduced. In summary, preoperative 3D reconstruction and simulation of the relevant organs are meaningful for: the intraopera-

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Fig. 6.13  Left hemi-hepatectomy simulated operation (a) Open the liver and dilate the bile duct; (b) Remove intrahepatic bile duct stones; (c) Cut off the hepatic vein; (d) Suture the broken end of hepatic vein; (e) Continue to cut the liver parenchyma; (f) Cut off the left portal vein; (g) Suture the stump of the left portal vein; (h) There was no residual

stone in the right half of the liver and its ducts; (i) Residual calculi in the intrahepatic bile duct can be seen after the left liver and its ducts are transparent; (j) Suture the liver cross-section; (k) The remaining right liver was examined again after transparency, and no residual stones were found

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tive selection of the optimal surgical path, reduction of surgical damage including to the adjacent tissue, the improvement of the positioning accuracy, the performance of the complex surgery, and improved success rate of surgery. With the continuous advancement of computer and medical technology, as well as the further research and development of medical 3D image visualization reconstruction software and virtual surgery systems, this advanced multidisciplinary technology will play a more significant role in clinical application, and become an indispensable tool assisting liver surgeons (Resource 6.1).

References Bro-Nielsen M, Cotin S, Delingette H, Clement JM, Ayache N, Marescaux J. Geometric and physical representations for a simulator of hepatic surgery. In Proceedings of the medicine meets virtual reality, San Diego, CA, Jan 17–20, 1996, pp. 139–151.

Fang C, Zhou W, Huang L, et  al. Studies on the hepatic three-­ dimensional reconstruction and virtual surgery using the hepatic images of the digitized virtual Chinese human female number 1 database. Chin J Surg. 2005;43(11):682–6. Kockro RA, Serra L, Tseng-Tsai Y, et  al. Planning and simulation of neurosurgery in a virtual reality environment. Neurosurgery. 2000;46(1):118–35. Lamadé W, Vetter M, Hassenpflug P, et  al. Navigation and imageguided HBP surgery: a review and preview. J Hepato-Biliary-­ Pancreat Surg. 2002;9:592–9. Pflesser B, Petersik A, Pommert A, et al. Exploring the visible human’s inner organs with the VOXEL-MAN 3D navigator. Stud Health Technol Inform. 2001;81:379–85. Soler L, Delingette H, Malandain G, et al. An automatic virtual patient reconstruction from CT-scans for hepatic surgical planning. Stud Health Technol Inform. 2000;70:316–22. Tian J, Xue J, Dai Y, et  al. A novel software platform for medical image processing and analyzing. IEEE Trans Inf Technol Biomed. 2008;12(6):800–11. Wigmore S, Redhead D, Yan X, Casey J, Madhavan K, Dejong C, Currie E, Garden J.  Virtual hepatic resection using threedimensional reconstruction of helical computed tomography angioportograms. Ann Surg. 2001;233:221–6. https://doi. org/10.1097/00000658-­200102000-­00011.

7

Application of Indocyanine Green Fluorescent Imaging in Biliary Surgery Chihua Fang and Wen Zhu

7.1

Introduction

Molecular imaging (MI) is a comprehensive interdisciplinary subject that is the product of the combination of medical imaging technology and modern molecular biology. It involves the qualitative and quantitative study of organisms in vivo at the cellular and molecular levels through imaging technology and methods. Through MI, various pathophysiological processes in the body at the cellular or subcellular levels can be reflected and identified. Compared with the current clinical imaging studies of the human form from the morphological and structural aspects, molecular imaging focuses on revealing the occurrence and development process of diseases at the level of biochemical and intracellular pathways. Optical imaging, as an essential component and living force of molecular imaging, combines high sensitivity with no ionizing radiation. It can detect the optical signals emitted by endogenous or exogenous contrast agents and present to the observer the coding information of the biochemistry process in vivo carried by the signal. In recent years, with continuous expansion of molecular fluorescence imaging technology in surgical applications, indocyanine green (ICG), as a tracer or contrast agent, has shown considerable application prospects. This chapter introduces the application of ICG fluorescent imaging in the accurate diagnosis and management of biliary surgery in recent years. ICG is a near-infrared fluorescent dye, which can be excited at wavelengths of 750–810 nm and emits fluorescence that peaks at about 840  nm (Jonak et  al. 2011; Landsman et  al. 1976). In this spectral region, the near-infrared light emits a fluorescent signal with a penetration depth of 5–10 mm due to the low absorption of hemoglobin or water; moreover, this region can be detected by an imaging device that is sensitive to infrared light and has a suitable filter

C. Fang (*) · W. Zhu Zhujiang Hospital, Southern Medical University, Guangzhou, China

(Morita et al. 2013). Notably, ICG has been approved by the US Food and Drug Administration (USFDA) and the China Food and Drug Administration (CFDA) for human use. As a medical imaging medium, it has been used in humans for over 50 years. Because the near-infrared light has more substantial penetrating power than other light bands, ICG has a critical advantage as the optical imaging medium of human body tissue. In recent years, there has been an explosion of interest in the application of ICG fluorescent imaging technology in surgery; however, it can only be used as a tracer or contrast agent. The application of ICG fluorescence imaging in hepatobiliary surgery has been rapidly expanding since Ishizawa first reported the use of ICG fluorescent imaging in hepatocellular surgery (Ishizawa et al. 2009). Congenital anatomical variations of the extrahepatic biliary system are common. The surgeon’s misidentification or improper management of these variations may lead to disastrous adverse events, such as bile duct injury. Therefore, variations in the anatomy of the bile duct should be recognized in each operation. Near-infrared fluorescence imaging has received widespread attention. As ICG is introduced into the human body via intravenous administration, it can be selectively absorbed by hepatocytes and excreted into bile in a free form (Osayi et al. 2015). It will pass into the common bile duct and gallbladder through each level of the bile duct, and finally be discharged into the duodenum. Light is applied around the peak absorption wavelengths (750–810  nm) exciting the ICG molecules which then return to their unexcited state by emitting light around 850 nm. Then, the emitted light signal is captured by the imaging system and processed to form the fluorescence image of extrahepatic bile ducts. Surgeons can grasp the intraoperative conditions in real time and provide substantive guidance and assistance for operation. At present, preoperative medical imaging techniques for the biliary tract mainly include MRCP, CT, and direct cholangiography. Through these imaging techniques, surgeons can preliminarily understand the anatomy and pathology of the biliary tract and determine the operation method.

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However, it is difficult to identify the bile ducts, to decrease the risk of bile duct injury intraoperatively, when there are adhesion, inflammation, and reoperation. Intraoperative cholangiography has been considered as a reliable prophylactic technique; however, it has not been supported by costeffectiveness analysis. The question about selective intraoperative cholangiography is that it lacks clear implementation standards, and also, the biliary tract injury may have already occurred when surgeons are faced with difficulties in preparing for cholangiography. Intraoperative cholangiography also has the following drawbacks:

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bile duct injuries include bile duct stricture, biliary leakage, and transection or clipping of the bile duct. Though some of the bile duct injuries are attributed to the “learning curve” in the theatre of operation, the primary cause of these injuries is misinterpretation of biliary anatomy, which accounts for 71%–97% (Way et  al. 2003). To avoid such tragic errors, surgeons have been developing and introducing techniques that can directly display the location and course of extrahepatic bile ducts. Intraoperative cholangiography has been considered as a reliable tool for preventing bile duct injury during surgery. However, it is not recommended for routine use due to certain limitations in its implementation. • It is an invasive examination, which requires puncture of In recent years, various intraoperative navigation techniques the cystic duct or injection of contrast medium via the end such as ICG-mediated near-infrared fluorescence of the cystic duct. cholangiography, which can display the extrahepatic biliary • The operation is complicated, which requires highly qual- system in real-time, have been widely used in surgery (Dip ified radiology technicians to operate, and there is a risk et al. 2014). Because of the fluorescent property of ICG and of radiation exposure. its biliary excretion properties, the emitted light intensity • Iodine may lead to the risk of an allergic reaction. within the bile duct allows real-time enhanced visualization According to the statistics, allergic reactions to high-­ of the course of the extrahepatic bile duct, which can greatly osmolar ionic contrast occur between 4% and 12%, while increase the safety of the procedure by minimizing the such reactions present in about 0.7% to 3% of patients incidence of intraoperative inadvertent bile duct injury. with low-osmolar nonionic contrast (Trcka et  al. 2008; Normal anatomy of the biliary tract can be altered due to Lieberman and Seigle 1999). It is estimated that severe anatomic variations of extrahepatic bile ducts or local lesions anaphylaxis occurs in 0.1% to 0.4% with ionic contrast in the Calot’s triangle. Variations of the hepatobiliary agents and 0.02% to 0.04% with nonionic contrast agents vasculature include the cystic duct, right hepatic duct, (Trcka et al. 2008; Caro et al. 1991). common bile duct, cystic artery, and right hepatic artery. • There is a risk of bile duct injury. Severe inflammation of 85% of the aberrant anatomy is observed within Calot’s the cystic duct and common bile duct is a precipitating triangle (Sanjay et al. 2012). Anatomical variation is reported event that will result in rupture of the cystic duct or as a contributing risk factor for bile duct injury in LC. The perforation of the common bile duct when a catheter is main reasons leading to misinterpretation are as follows: inserted into the common bile duct. • There is a certain failure rate of angiography. • The operating surgeon is not familiar with surgical anatomy under laparoscope and is not careful in identifying By contrast, the prominent advantages of ICG fluoresthe anatomical area of the Calot’s triangle. cence imaging are obvious: real-time imaging with high • Improper gallbladder traction. Excessive or insufficient specificity and sensitivity; non-invasiveness; cost-effective; traction will lead to changes in the relationship between safety (radiation-free); ease of use, minimal learning curve the “tree tubes,” resulting in bile duct misidentification. (Pesce et al. 2015). With an incarcerated gallbladder neck stone and thin common bile duct, the excessive upward traction of the gallbladder may lead to the displacement of the common 7.2 ICG Fluorescence Imaging bile duct and bile duct injury. • The change of anatomical position under laparoscope in Preventing Bile Duct Injury after the rotation of the lens may result in misidentification. in Laparoscopic Cholecystectomy • Anatomical and pathological factors: Congenital anatomLaparoscopic cholecystectomy (LC) has been considered the ical variation or displacement of the bile duct due to gold standard for gallbladder diseases. As a classic minimally repeated inflammation and adhesion in the Calot’s trianinvasive surgical technique, LC has the advantages of less gle may lead to unclear dissection. pain, shorter hospitalization time, and faster recovery. However, as LC was gaining popularity, the tendency of bile Therefore, the key to prevent extrahepatic biliary injuries duct injury increased. Statistical analyses show that the is to detect the anatomical variations of the extrahepatic bile incidence of bile duct injury in LC ranges between 0.3% and ducts and identify the position of the bile ducts (Fig. 7.1). 1.4% (Abbasoğlu et  al. 2016). The main manifestations of Preoperative MRCP and intraoperative cholangiography

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Fig. 7.1  ICG fluorescence cholangiography shows cystic duct, common bile duct, and common liver duct. The cystic duct enters the common bile duct on the left

Fig. 7.2  ICG fluorescence imaging of extrahepatic biliary ducts under SPY fluorescence mode showed clear differentiation of cystic duct, common bile duct, and left/right hepatic duct

can better display the biliary anatomy and aid timely detection of biliary tract variations. Although MRCP can help biliary surgeons to understand the anatomy of the biliary tract sensitively before operation, it cannot be used as a realtime guide during operation. Studies showed that the use of intraoperative direct cholangiography can reduce the risk of bile duct injury from 0.58% to 0.39% (Flum et  al. 2003). However, the advantages of cholangiography in conventional surgery have been questioned. ICG near-infrared molecular fluorescence can better display the biliary tract after intravenous injection. Due to its relatively poor penetration into surrounding tissues, it can enhance the display of the extrahepatic biliary tract, especially the Calot’s triangle (Fig.  7.2). Through ICG fluorescence imaging, the

anatomy and variations of the bile duct, cystic duct, common bile duct, and common hepatic duct can be observed. After dissociating the tissues around the vasculature, the anatomical structure of the extrahepatic bile duct can be clearly developed by ICG near-infrared fluorescence. At this time, transection of the cystic duct is safer (Fig. 7.3), which provides real-time guidance for beginners or inexperienced physicians. For patients whose normal anatomical structure has changed significantly after repeated biliary tract surgery or whose anatomy is difficult to distinguish, ICG fluorescence imaging can provide real-time intraoperative bile duct imaging to help doctors locate the bile duct, avoid inadvertent injury, and guide surgical treatment in real time (Figs. 7.4 and 7.5).

164 Fig. 7.3  Before dissociating the cystic duct, the course of the cystic duct was determined by ICG molecular fluorescence imaging, so as to sever the cystic duct more safely

Fig. 7.4  ICG fluorescent imaging of the extrahepatic biliary tract helps to identify the biliary system. No fluorescence development was seen in the front pipe of the electrocoagulation hook, which was considered as a thick gallbladder artery. Fluorescent below is the cystic duct, which helps the doctor locate the bile duct and avoid damage

Fig. 7.5  The biliary tract development of ICG fluorescence indicated a low confluence between the cystic duct and the common bile duct, which could help avoid intraoperative injury to the common bile duct

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7  Application of Indocyanine Green Fluorescent Imaging in Biliary Surgery

7.3

I CG Fluorescence Imaging in the Diagnosis and Management of Biliary Diseases

7.3.1 I CG Fluorescence Imaging in Locating Bile Duct During Reoperation of the Biliary Tract Every hepatobiliary surgeon must locate the bile duct, identify bile duct lesions correctly, and avoid bile duct injury in biliary surgery. Current preoperative imaging techniques for assessing the biliary tract include MRCP, CT, and B-ultrasound. Through these imaging modalities, surgeons can understand the anatomy and pathology of the biliary tract preliminarily and determine operation approaches. In recent years, near-infrared fluorescence imaging technology has gradually seized people’s attention. Through intraoperative real-time fluorescence imaging, surgeons can grasp the intraoperative situation while performing the procedure and Fig. 7.6  For patients undergoing biliary tract reoperation, intraoperative ICG fluorescent imaging was used to display the extrahepatic biliary tract to avoid biliary tract injury

Fig. 7.7  No fluorescence development was observed in the bile duct when the first porta hepatis was viewed under fluorescence state, according to which, the location and degree of bile duct stricture in hilar of the liver could be determined and appropriate repair and reconstruction surgical methods could be selected

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provide substantial guidance and assistance for the operation. For patients with a history of multiple biliary tract surgery, it is recommended that ICG fluorescence imaging technology should be used to help locate the biliary tract and identify the hilar tissue intraoperatively, if the hospital has the necessary equipment; choledocholithotomy should be performed after accurate identification of the bile duct and duodenum from the first porta hepatis with tissue contracture and unclear structure, which is conducive to avoid iatrogenic injury (Fig. 7.6).

7.3.2 I CG Fluorescent Imaging in Diagnosis and Management of Biliary Stricture ICG fluorescent imaging technology can detect the location and extent of hilar biliary stricture and guide the selection of appropriate repair and reconstruction surgery methods (Fig. 7.7).

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7.3.3 I CG Fluorescence Imaging in Finding Biliary Anastomosis After Reoperation of the Biliary Tract For biliary tract surgery, full exposure of the surgical field is helpful to identify variations of the bile duct and avoid iatrogenic bile duct injury. After repeated operations, extensive adhesion fibrosis or scar formation in the right upper abdominal cavity may develop. Postoperative adhesions lead to significant changes in the normal anatomy and increase the difficulty in identifying the common bile duct. Reoperation following multiple biliary operations is a complex procedure; dissociating and searching for the bile duct is an important step, and sometimes challenging. For the patient who has a history of biliary tract surgery, especially Roux-en-Y anastomosis, the extrahepatic biliary tract is buried deep in an envelope of severe scar adheFig. 7.8  For patients with a history of previous Roux-Y choledochojejunostomy, the hilar tissues could be clearly identified by ICG fluorescent imaging because bile containing indocyanine green was present in the ascending jejunal loops. The fluorescence in this figure shows the ascending jejunal loops

Fig. 7.9  Intraoperative use of ICG fluorescent imaging required to locate ascending jejunal loops for choledochojejunostomy

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sion. At reoperation, imprecise incision can easily injure the colon were adhered to the porta hepatis, stomach, and duodenal bulb, and mesentery, and even severely damage the hepatic hilus structure. The more conservative approach is to mobilize the encapsulated lower right hepatic margin. From the right approach, dissociate along the visceral surface against the liver capsule to the left, mainly with sharp dissection. Dissociate from shallow to deep, until the hepatoduodenal ligament is exposed. Identify the ascending jejunal loop by ICG fluorescent imaging and locate the anastomotic site. From the original anastomotic site, search for the common bile duct, and puncture to confirm. Alternatively, accurate bile duct incision or anastomotic removal can be performed after administration of ICG through which ascending jejunal loops and extrahepatic bile ducts can be fully displayed under fluorescence (Figs. 7.8 and 7.9).

7  Application of Indocyanine Green Fluorescent Imaging in Biliary Surgery

7.3.4 I CG Fluorescence Imaging in Searching for Dilated Intrahepatic Bile Duct Patients with complicated hepatolithiasis usually have a long course, recurrent cholangitis, and formation of hepatic atrophy/hyperplasia. In some patients with hepatolithiasis, dilated bile ducts and stones are located in the segments VII and VIII and the bare area of the liver; patients are also intolerant of hepatectomy. In order to avoid blind exploration and inadvertent injury, ICG-mediated near-infrared fluorescence imaging of bile ducts can be used to navigate the biliary surgery (Fig. 7.10). It helps surgeons accurately locate distal dilated bile ducts, reducing time spent blindly cutting liver parenchyma in search of the bile duct, significantly shortening the duration of the operation.

7.3.5 I CG Fluorescence Imaging in Defining Cholangiocarcinoma Tumor Boundaries Cholangiocarcinoma is an uncommon malignancy with poor prognosis, and surgery remains the only curative treatment option. Patients with intrahepatic cholangiocarcinoma and hilar cholangiocarcinoma often require extensive hepatectomy, or even extended left/right liver lobectomy combined caudate lobectomy. Obtaining R0 resection and ensuring the safety of surgery is the goal of hilar cholangiocarcinoma surgery and the primary condition for preventing postoperative recurrence. For patients with impaired cholestasis, how to preserve the volume and function of the remaining liver to the maximum extent has become one of the focuses of liver surgery. The critical step of liver tumor operation is to locate the tumor accurately and define the tumor boundary and range of resection. If the resection

Fig. 7.10  Intraoperative ICG fluorescent imaging of the biliary tract plays a role of “navigation” in biliary tract surgery, accurately locating the distal dilated bile duct and guiding the accurate incision of liver parenchyma for stone extraction

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range is too small, it will lead to residual tumor; and if the resection scope is too large, it will increase the risk of vascular injury and liver failure. At present, it is mainly based on preoperative imaging, intraoperative naked eye findings, and exploration results, combined with clinical experience to make a comprehensive judgment. Compared with traditional imaging methods such as B-ultrasound CT, and MRI, ICG fluorescent imaging has the advantages of high contrast fluorescence imaging between healthy liver tissue and tumor tissue. Moreover, ICG fluorescent imaging reflects the pathological changes of cells and molecules in  vivo, and the boundary of the cell functional level is preliminarily realized. Therefore, ICG fluorescent imaging can locate liver tumors in real time during operation and help to define the tumor boundary and the scope of hepatectomy through this unique imaging method.

7.3.6 I CG Fluorescent Imaging in Determining the Boundary of Liver Resection In patients with hilar cholangiocarcinoma and some patients with hepatolithiasis, when resection of a hepatic segment/ region is required, intraoperative ICG fluorescent imaging can help to clearly display and confirm the cross section of liver resection; and guide the accurate hepatic parenchymal disconnection in real time. At present, Glisson pedicle occlusion and ultrasound-guided portal vein puncture staining are commonly used to distinguish the lobe/segmental boundary in anatomical hepatectomy. Both methods have certain limitations. Firstly, indigo solution, as a common staining agent of portal vein puncture, cannot guide the whole process because of its short residence time in the liver. Secondly, it is difficult to obtain a clear hepatic lobe/segment boundary

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when the Glisson pedicle occlusion is used on the uneven surface of the cirrhotic liver and the surface of the liver with a history of abdominal surgery and covering fibrous tissue; also, the ischemic boundary of the liver parenchyma is not as evident as the liver surface during the process of liver dissection, and it does not play a good guiding role. In 2008, Aoki et al. first applied ICG fluorescent imaging to the differentiation of the intrahepatic hepatic lobe/segment (Aoki et  al. 2008). The technique was then further developed by using a diluted ICG solution as a fluorescent agent and a more advanced fluorescent image fusion system. At present, the use of ICG fluorescent imaging to display the liver lobe/segment can be performed by two methods. Positive Display Method  In the positive display method, the portal vein of the hepatic segment to be resected is identified by intraoperative B ultrasound and 3D visualization models. A small amount of diluted ICG solution is extracted using a fine puncture needle and injected into the target portal venous branches for fluorescence detection, showing the hepatic lobe/segment to be resected. The fluorescence signal of the positive display method is reliable, but this method is more complicated than the negative display method. Negative Display Method  In the negative display method, the portal vein of the liver segment to be resected is separated and ligated with the help of the 3D reconstructed model. A small amount of diluted ICG solution is injected intravenously for fluorescence detection, revealing the hepatic lobe/ segment to be preserved. The negative display method is usually suitable for hepatic segment where portal venous branches are easily exposed. The disadvantage of this method lies in its low concentration of ICG accumulation, and hence weak fluorescence signal. The positive display method is generally suitable for the development of liver segments or subhepatic segments Fig. 7.11  Left intrahepatic cholangiocarcinoma. Left hepatic ICG excretion obstruction due to tumor invasion of the left hepatic duct, showing the left hepatic boundary clearly

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supplied by fewer liver pedicles (1–2) because this method requires injection of ICG after fine-needle aspiration in the target liver lobe/segment. While, the negative display method is suitable for hepatic segment where portal venous branches are easily exposed, usually for development of liver segments supplied by more hepatic pedicles (≥ 3 branches) or development of semi-liver. In clinical application, it is found that both positive and negative display methods present a specific failure rate, which often occurs in patients with vascular anatomic variations in porta hepatis. For the patients whose target hepatic segment/ pedicle are challenging to dissect and lead to puncture failure, a negative display method should be used. When there is more pedicle supply in the target liver segment, if the hepatic pedicle is only partially blocked, the negative display method is more prone to a failure to stain, so the positive display method should be used. At present, a 3D portal vein display can be realized both preoperatively and intraoperatively. Therefore, intraoperative ultrasound and 3D visualization systems can be combined to accurately understand the portal venous variations, which is helpful for portal venous puncture and hepatic pedicle anatomy. Appropriate display methods can be selected according to actual conditions to further improve the success rate of ICG fluorescence development. In the course of clinical application, we used a negative display method and a positive display method to divide the hemi-hepatic boundary, respectively, and achieved good results. We realized a strong visual segmentation effect of the liver surface and the 3D staining of liver parenchyma. Moreover, using the positive and negative methods provides consistent results when there is hepatic ischemia after blocking the corresponding portal vein and hepatic artery. The dynamic situation was observed concurrently with the operation, and the direction of hepatectomy was adjusted and corrected according to the fluorescence boundary of liver parenchyma, which confirmed that the method has good surgical guidance value (Figs. 7.11, 7.12, 7.13, and 7.14).

7  Application of Indocyanine Green Fluorescent Imaging in Biliary Surgery Fig. 7.12  Fluorescence of the specimen after left hemi-hepatectomy showed a clear tumor boundary

Fig. 7.13  For one patient who requires right hemi-­ hepatectomy for hilar cholangiocarcinoma, the target liver segment was clearly displayed by the negative display method, and the boundary between left and right liver was clearly observed

Fig. 7.14  The left half of the liver was clearly displayed by negative display method, and the boundary between the left and right liver was clearly observed

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7.3.7 I CG Fluorescent Imaging in Detection and Management of Biliary Leakage In recent years, due to the improvement of surgical techniques and perioperative work, the safety of biliary tract surgery has been improved, and mortality has been reduced. Although the overall postoperative complications are declining, bile leakage after liver surgery continues to be reported with unchanged incidences, ranging from 3.6% to 33% (Capussotti et  al. 2006; Tanaka et  al. 2002). Postoperative bile leakage is a serious surgical complication, often occurring in the hepatic duct stump and liver section. Bile leakage increases the perioperative risk of abdominal infection, sepsis, liver failure, and even multiple organ failure, prolongs hospital stay, and even increases perioperative mortality. It is especially important to reduce the occurrence of bile leakage. The management of bile leakage should highlight the importance of prevention, early detection, and timely treatment. It is imperative to detect potential leakage before closure. The current intraoperative leak testing method mainly is injection of normal saline or methylene blue solution through the cystic duct or the open bile duct on the liver section after blocking the common bile duct, and then to observe whether biliary leakage or staining is present. Injection of normal saline is a low-cost, non-toxic, and reproducible approach; however, the clarity of aqueous solution makes it difficult to detect small leaks. Injection of dyes such as methylene blue can detect biliary leakage more clearly because of their high contrast with liver parenchyma, however, these dyes can often stain the surrounding liver tissue at the same time, so it is difficult to locate the leakage accurately. Intraoperative cholangiography is an effective method for leak detection, but it is not the first choice because of its complicated radiation exposure risks and attendant safety procedures during Fig. 7.15  After right hemi-hepatectomy for hilar cholangiocarcinoma, there was no bile leakage at the broken end of the right hepatic duct

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the operation. With the application of ICG fluorescent technique in hepatobiliary surgery, the effectiveness of intraoperative ICG fluorescent imaging in detecting small bile duct leakage in liver transection has been confirmed. The detection of bile leakage after hepatectomy by ICG fluorescent imaging is mainly based on the biological characteristics of the bile duct excretion through the bile duct system. Bile duct excretion begins 15 min after the intravenous injection of ICG. Therefore, the method is to temporarily block the distal common bile duct after hepatectomy, then inject ICG, through the gallbladder duct or cross-section bile duct to carry out fluorescence imaging to detect bile leakage in the transect of the liver, and then to detect and deal with the bile leakage promptly during the operation. As shown below in one patient with hilar cholangiocarcinoma who underwent right hemi-hepatectomy, the bile duct was temporarily blocked after ICG injection through the bile duct, and the extrahepatic bile duct was developed. There was no fluorescence residue in the right hepatic section (Figs. 7.15 and 7.16).

7.3.8 I CG Fluorescent Imaging in Detection and Management of Anastomotic Leakage Choledochojejunostomy is often used in the repair of bile duct injuries, excision of extrahepatic bile duct lesions, and biliary reconstruction in the treatment of biliary calculi. It mainly involves, those who had extrahepatic or hilar bile duct lesions, including tumors, congenital cholangiectasis, inflammatory stenosis; and the reconstruction of biliary drainage is necessary after pathological bile ducts are resected. The following cannot undergo this procedure: Those who experienced iatrogenic bile duct injury and the

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Fig. 7.16  After right hemi-hepatectomy, no fluorescent residue was found in the residual liver section, indicating no bile leakage in the hepatic section

Fig. 7.17  The indwelling supporting tube of the right hepatic duct. No fluorescence development was observed at the choledochojejunostomy, while bile and fluorescence were observed in the supporting tube of the right hepatic duct, indicating no leakage at the choledochojejunostomy and unobtrusive right bile duct drainage

local repair of the bile duct; those with advanced periampullary cancer whose tumor cannot be removed and palliative treatment of obstructive jaundice are needed; those who have intrahepatic bile duct stones associated with hilar bile duct stricture and need the resection of the strictured bile duct or open plastic surgery. The surgeon must ensure there is no

stricture above the anastomosed bile duct. It is necessary to detect the presence of bile leakage in the biliary anastomosis during surgery. Since ICG near-infrared molecular fluorescence can be excreted from bile, it is possible to effectively observe the presence of bile leakage in the biliary anastomosis by fluorescence imaging (Figs. 7.17 and 7.18).

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Fig. 7.18 After choledochojejunostomy, no obvious fluorescence development was observed at the anastomosis, suggesting no bile leakage at the choledochostomy

References Abbasoğlu O, Tekant Y, Alper A, et al. Prevention and acute management of biliary injuries during laparoscopic cholecystectomy: Expert consensus statement. Ulus Cerrahi Derg. 2016;32(4):300–5. Aoki T, Yasuda D, Shimizu Y, et al. Image-guided liver mapping using fluorescence navigation system with indocyanine green for anatomical hepatic resection. World J Surg. 2008;32:1763–7. https://doi. org/10.1007/s00268-­008-­9620-­y. Capussotti L, Ferrero A, Vigano L, Sgotto E, Muratore A, Polastri R. Bile leakage and liver resection: where is the risk? Arch Surg. 2006;141:690–4. Caro JJ, Trindade E, McGregor M.  The risks of death and of severe nonfatal reactions with high- vs low-osmolality contrast media: a metanalysis. AJR Am J Roentgenol. 1991;156:825–32. Dip FD, Asbun D, Rosales-Velderrain A, et  al. Cost analysis and effectiveness comparing the routine use of intraoperative fluorescent cholangiography with fluoroscopic cholangiogram in patients undergoing laparoscopic cholecystectomy. Surg Endosc. 2014;28(6):1838–43. Flum DR, Dellinger EP, Cheadle A, Chan L, Koepsell T. Intraoperative cholangiography and risk of common bile duct injury during cholecystectomy. JAMA. 2003;289(13):1639–44. https://doi. org/10.1001/jama.289.13.1639. Ishizawa T, Fukushima N, Shibahara J, et al. Real-time identification of liver cancers by using indocyanine green fluorescent imaging[J]. Cancer. 2009;115(11):2491–504. Jonak C, Skvara H, Kunstfeld R, Trautinger F, Schmid JA. Intradermal indocyanine green for in vivo fluorescence laser scanning microscopy of human skin: a pilot study. PLoS One. 2011;6(8):e23972. https://doi.org/10.1371/journal.pone.0023972. Landsman ML, Kwant G, Mook GA, et  al. Light-absorbing properties, stability, and spectral stabilization of indocyanine green. J Appl Physiol. 1976;40:575–83. https://doi.org/10.1152/ jappl.1976.40.4.575.

Lieberman PL, Seigle RL.  Reactions to radiocontrast material: anaphylactoid events in radiology. Clin Rev Allergy Immunol. 1999;17:469–96. Morita Y, Sakaguchi T, Unno N, et al. Detection of hepatocellular carcinomas with near-infrared fluorescence imaging using indocyanine green: its usefulness and limitation. Int J Clin Oncol. 2013;18:232– 41. https://doi.org/10.1007/s10147-­011-­0367-­3. Nishino H, Hatano E, Seo S, et al. Real-time navigation for liver surgery using projection mapping with indocyanine green fluorescence: development of the novel medical imaging projection system. Ann Surg. 2018;267(6):1134–40. Osayi SN, Wendling MR, Drosdeck JM, Chaudhry UI, Perry KA, Noria SF, Mikami DJ, Needleman BJ, Muscarella P II, Abdel-­Rasoul M, et  al. Near-infrared fluorescent cholangiography facilitates identification of biliary anatomy during laparoscopic cholecystectomy. Surg Endosc. 2015;29(2):368–75. Pesce A, Piccolo G, La Greca G, Puleo S. Utility of fluorescent cholangiography during laparoscopic cholecystectomy: a systematic review. World J Gastroenterol. 2015;21(25):7877–83. https://doi. org/10.3748/wjg.v21.i25.7877. Sanjay P, Tagolao S, Dirkzwager I, Bartlett A.  A survey of the accuracy of interpretation of intraoperative cholangiograms. HPB (Oxford). 2012;14(10):673–6. https://doi. org/10.1111/j.1477-­2574.2012.00501.x. Tanaka S, Hirohashi K, Tanaka H, Shuto T, Lee SH, Kubo S, Takemura S, Yamamoto T, Uenishi T, Kinoshita H. Incidence and management of bile leakage after hepatic resection for malignant hepatic tumors. J Am Coll Surg. 2002;195:484–9. Trcka J, Schmidt C, Seitz CS, Bröcker E-B, Gross GE, Trautmann A.  Anaphylaxis to iodinated contrast material: nonallergic hypersensitivity or IgE-mediated allergy? AJR Am J Roentgenol. 2008;190:666–70. Way LW, Stewart L, Gantert W, Liu K, Lee CM, Whang K, Hunter JG. Causes and prevention of laparoscopic bile duct injuries: analysis of 252 cases from a human factors and cognitive psychology perspective. Ann Surg. 2003;237:460–9.

8

Application of Endoscopic Techniques in Biliary Tract Surgery Zhaohui Tang and Chihua Fang

8.1

Introduction

In 1806, German physician Philip Bozzini invented an optical device that used a candle as a light source to inspect the interior of the bladder and rectum (Bozzini 1806), which was historically recorded as the earliest endoscopic instrument. Dr. Bozzini set the stage for over 200 years of innovations in endoscope development. Endoscopy has experienced the development stage of rigid endoscopy, semiflexible lens endoscopy, fiber-optic endoscopy, and electronic endoscopy. Because of the critical status of the human digestive system, the progress of endoscopy has often played an essential role in the overall advancement of digestive tract disease diagnosis and treatment. Gastrointestinal endoscopy has undergone the stages of rigid-wire endoscopy, fiber-optic endoscopy, electronic endoscopy, radio-electronic endoscopy-capsule endoscopy. The continuous development of gastrointestinal endoscopy provides clinicians with an accurate diagnostic basis. Currently, the commonly used endoscopes are fiberoptic endoscopy and tubular electronic endoscopy, both of which have relatively stable and accurate clinical applications. However, the pain caused by the two types of endoscopy is obvious. This problem has been solved by capsule endoscopy. Although capsule endoscopy has seen tremendous advances in a short period of time, there are still some technical problems to be solved. With the continuous integration of digital science information technology, artificial intelligence technology, and minimally invasive surgery in the new era, it is believed that endoscopic robot technology will become an inevitable trend of digestive tract endoscopy.

Z. Tang Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China

8.2

Duodenoscopy

Fiberoptic duodenoscopy, one of the most rapidly developing digestive endoscopes, has opened new vistas in the diagnostic of duodenal, biliary, and pancreatic diseases. Specialized fiberoptic duodenoscopy is a side-viewing instrument (JF-­ B2, Olympus), which is convenient for inspection of duodenal bulb and the major duodenal papilla, rendering cannulation easier; moreover, when the pyloric region and the duodenal bulb is markedly distorted, it can be changed into a straight or strabismus lens by replacing the contact lens. The endoscopy is usually thinner than the gastroscope, and has a long working length (1300–1600 mm); so, it can be inserted into the deep part of the duodenum. Since endoscopy has an extremely small diameter, especially in the front end, it facilitates reversal observation in the duodenal bulb. The hardness of the proximal portion and distal end of the duodenoscope varies; the soft distal portion and the strengthened proximal part satisfies the requirements of the duodenoscopy to be soft and flexible but also improves the performance of the front-end follower. The following surgical procedures are feasible with duodenoscopy: diagnostic endoscopic retrograde cholangiopancreatography (ERCP) and therapeutic ERCP; therapeutic ERCP includes endoscopic sphincterotomy (EST), endoscopic biliary drainage (EBD), endoscopic nose biliary drainage (ENBD), endoscopic retrograde pancreatodrainage (ERPD), and corresponding endoscopic fistula. Indications • Patient with suspected duodenal diseases that cannot be diagnosed by other examinations. • Differential diagnosis of benign and malignant duodenal ulcer. • Patient with suspected pancreatic and biliary diseases who is recommended to undergo ERCP.

C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_8

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Contraindications • Patients unwilling to cooperate, such as mental disorder or psychosis. • Severe cardiopulmonary disease and spinal deformity. • Severe esophageal, cardiac, and pyloric obstruction. • Patients who are not suitable for ERCP due to acute pancreatitis, biliary tract infection, and iodine allergy. ERCP with duodenoscopy is the most technically demanding and risky digestive endoscopic operation. Based on the actual situation in China, the ERCP Group of Digestive Medicine branch of the Chinese Medical Association has formulated the “Chinese guidelines for ERCP 2018” (2018). Indications for ERCP include obstructive jaundice, pancreatic or biliary ductal system diseases, suspicion for pancreatic cancer, pancreatitis of unknown cause, preoperative evaluation of chronic pancreatitis or pancreatic pseudocyst, manometry for sphincter of Oddi, and biliary stenting for leakage. Sphincterotomy is indicated in cases of the sphincter of Oddi dysfunction or stenosis, difficulty with biliary stenting or accessing the pancreatic duct, biliary strictures, bile duct stones, bile sump syndrome following choledochoduodenostomy, choledochocele, and in poor surgical candidates with ampullary carcinoma. Where laboratory or noninvasive imaging studies do not suggest that abdominal pain is due to pancreaticobiliary disease, the probability of meaningful discovery is low, and the risk of complications is high, ERCP is not advised. ERCP should only be performed when Oddi sphincter manometry is considered for this group of patients. For routine examination before cholecystectomy, preoperative ERCP should be considered only in patients with cholangitis or biliary obstruction, or with clinical and imaging findings suggesting cholelithiasis. ERCP is routinely performed for malignant obstruction of distal bile duct with the opportunity of surgical resection, but there is no evidence that preoperative biliary decompression can improve the prognosis of the operation. However, it can cause both preoperative and postoperative complications. In patients with acute cholangitis or severe pruritus for which the surgery may be delayed, preoperative ERCP can resolve the obstruction. Complications attributed to ERCP include (a) pancreatitis, hemorrhage after duodenal papillary sphincterotomy, infectious complications; (b) cholangitis, including cholecystitis and infection of peripancreatic effusion; (c) cardiopulmonary adverse reactions, usually caused by sedative drugs; (d) perforation. Patients should be informed that they may be hospitalized in the event of a complication. If perforation occurs, a surgical repair may be required. Post-ERCP pancreatitis (PEP) occurs in 3–15% of all ERCP procedures, and in high-risk patients, the risk of PEP can increase to more than 25% (Talukdar 2016; Fogel et al.

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2002; Elmunzer 2017). Endoscopists should inform the patient that PEP may lead to a prolonged hospital stay, and surgical treatment will be required; or even worse, it is very likely to lead to death. Possible factors (patients and operations) affecting the incidence of PEP should be considered when designing surgical protocols and signing informed consent. The incidences post-ERCP acute cholangitis and cholecystitis are 0.5–1.7% and 0.2% to 0.5%, respectively (Vandervoort et al. 2002; Freeman et al. 1996a, b; Lenriot et al. 1993). Bleeding is the most common complication of endoscopic biliary and/or pancreatic sphincterotomy. The incidence of post sphincterotomy bleeding after ERCP is reported to be 0.3% to 2% (Freeman et al. 1996a, b; Cotton et al. 2009; Rustagi and Jamidar 2015). The patients who underwent simple diagnostic ERCP without sphincterotomy and transmucosal puncture (such as simple stent indwelling) have minimal risk of massive postoperative bleeding. Factors that increase the incidence of bleeding include coagulopathy, preoperative acute cholangitis, anticoagulant therapy within postoperative 3 days, and unskillful operation. This condition can be treated by local injection of epinephrine, washing, and clamping of titanium clips. The incidence of perforation after ERCP ranges from 0.3% to 0.6%. Perforation can be mechanical perforation of the esophagus, stomach, duodenum caused by endoscopy, or caused by therapeutic procedures such as sphincter incision and guidewire placement. Anatomical changes caused by surgery can increase the risk of perforation (such as in patients undergoing previous Billmth II surgery via an injectable loop insertion). Perforation often requires surgery.

8.3

Choledochoscopy

In 1923, Bakes invented a laryngoscopic “choledochoscope” (Bakes 1923), and used it in an operation to inspect the lower end of the common bile duct, which was then officially published at the Berlin Institute of Surgery. It was later recognized as the earliest form. In 1930, Barlet successfully inspected the gallbladder by inserting the cystoscope through the fistula of the gallbladder. In 1941, McIver announced a rigid choledochoscope (produced by ACMI) co-designed with Reinhold Wappler. The choledochoscope was L-shaped, with a long arm of 45 cm, a short arm of 7 cm, and a diameter of 0.5  cm. It is equipped with a perfusion system and a photographic system. However, this mirror can only be used for observation but not for treatment, so it was not taken seriously. In 1965, the American doctor Shore cooperated with ACMI to develop optical fiber choledochoscope, also known as soft choledochoscope. The length of the choledochoscope was 50  cm, with a flexible end, freely adjustable focal length, and clear imaging. The endoscopy is very convenient; it can not only be used intraoperatively, but

8  Application of Endoscopic Techniques in Biliary Tract Surgery

also for choledochoscopy and treatment through postoperative T-tube sinus, which has undoubtedly expanded the scope of choledochoscopy application. Therefore, the fiber choledochoscopy invented by Shore is a milestone in the history of choledochoscopy. In 1971, Professor Kenji Chang of Japan Medical University formed a committee for the development of a choledochofiberscope, and Matsuda Manufacturing Institute took the lead in the trial production. Ten years later, Japan became the main and even the only exporter of fiberoptic choledochoscopes and developed various types of fiberoptic choledochoscope. The application of fiberoptic choledochoscopy in China began in 1978. The First Clinical Hospital of Beijing Medical University first published the clinical application of this technique in China. Although China started relatively late, the large number of cases in China coupled with centers of excellence has provided an environment with highly skilled and experienced practitioners. Choledochoscopy is mainly used for endoscopic examination of pancreaticobiliary duct and endoscopic surgery. It can be divided into rigid choledochoscopy, soft choledochoscopy, fiber choledochoscopy, electronic choledochoscopy, direct choledochoscopy, and peroral choledochoscopy. According to the technical classification of choledochoscopy, it can be divided into (a) intraoperative choledochoscopy, routine intraoperative choledochoscopy, laparoscopic choledochoscopy, robotic choledochoscopy; (b) postoperative choledochoscopy, which enters the biliary tract through the sinus tract of a T-tube (T-shaped drainage tube); through the jejunal blind loop after biliary anastomosis; through the cholecystostomy drainage sinus; (c) preoperative choledochoscopy, namely, percutaneous transhepatic choledochoscopy; and (d) transoral choledochoscopy, namely, duodenal choledochoscopy.

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Fig. 8.1  Initial puncture and catheterization

8.3.1 Preoperative Application Percutaneous transhepatic cholangioscopy (PTCS) refers to percutaneous transhepatic cholangiopuncture drainage (PTCD) followed by PTCD sinus dilatation. When the sinus is expanded to accommodate choledochoscope into the biliary tract, fiber choledochoscopy and treatment are performed (Figs. 8.1 and 8.2). Indications • Obstructive Jaundice For patients with suspected hepatobiliary duct dilatation via examination such as PTC, B-ultrasound, ERCP, and CT.  The critically ill patients can be treated with PTCD bile duct decompression and dissection first, and then PTCS to confirm the location and cause of obstruction. Fig. 8.2  Gradually replace to PTCD tube with a thicker diameter

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• Advanced Cholangiocarcinoma It can be treated with PTCS palliative catheterization and drainage, chemotherapy and laser therapy, or radionuclide probe implantation. • Complex Hepatolithiasis • Elderly Patients with Bile Duct Stones who Cannot Tolerate Surgery Stones can be removed by PTCS lithotripsy, or combined with perfusion lithotripsy, oscillatory lithotripsy, etc. • Dilation of Benign Biliary Strictures Traumatic stricture and stricture of cholangioenterostomy. • Intrahepatic Bile Duct Ascariasis • Bile Duct Malformation Especially for elderly patients with high-risk obstructive jaundice and patients with advanced biliary tract tumors, the choledochoscope has played a positive role in relieving biliary obstruction and related symptoms, and sometimes even become the main treatment for this disease. Contraindication • Patients with no dilatation of intrahepatic bile duct. • Abnormal blood coagulation and platelets below 80,000/ mm3. • Liver or kidney failure. • Liver diseases, such as portal hypertension with liver cirrhosis, hepatic hemangioma. • Heart failure; patients unwilling to cooperate. Complications • Biliary Hemorrhage It usually occurs in patients with abnormal coagulation function, when liver parenchyma is punctured or sinus tract is dilated, or when larger stones are removed. • Bile Leakage or Biliary Peritonitis It usually occurs when puncture or replacement of a drainage tube is too early or when a drainage tube falls off. • Fever Transient. The drainage tube should be kept unobstructed and antibiotics should be used if necessary. • Nausea and Vomiting It usually occurs during the sinus dilatation or during the examination and stone removal process, mainly caused by stimulation from injecting water too quickly. • Cardiovascular Accident

8.3.2 Intraoperative Application Indications • Unknown preoperative diagnosis of biliary diseases. Suspected biliary tract space-occupying lesions need definite diagnosis during operation. If there is stenosis of the biliary tract, biopsies are required for the selection of surgical procedures.

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• Preoperative diagnosis is not consistent with intraoperative diagnosis. • When there is a small number of intrahepatic bile duct stones, and when surgical removal is difficult, intraoperative choledochoscope can be carried out; the choledochoscope can also be used to determine whether the stones are completely removed. • Inspection of omitted bile duct stones after cholecystostomy. • Removal of stones in laparoscopic choledocholithotomy. Advantages • Reduced the incidence of residual stones after biliary tract surgery. • Intraoperative cholangioscopy is helpful for the diagnosis of the lesion and provides the basis for the choice of surgical methods. Disadvantages • Intraoperative choledochoscopy is not convenient, and it is not as easy as postoperative choledochoscopy in stone removal. • Prolonged exposure of the wound; salt and bile spillage can easily contaminate the abdominal cavity. • Laparoscopic choledocholithotomy with fiberoptic choledochoscope can easily damage the choledochoscope.

8.3.3 Postoperative Application Indications • Known or suspected residual biliary stones. • Biliary tumor or suspected biliary space-occupying lesions need to be confirmed by pathology. • Advanced choledochal tumors with obstructive jaundice require choledochoscope treatment. • Biliary tract malformations or stenosis. • Biliary ascariasis. • Biliary bleeding. • Foreign body in the biliary tract. • Selective cholangiography. • Sclerosing cholangitis (the only reliable diagnostic method). • Study on the dynamics of biliary tract. Contraindication • Patients with apparent coagulation abnormalities. • Patients with severe cardiopulmonary dysfunction. • Patients with fever caused by issues other than biliary tract disease. Complications • Fever It can occur after choledochofiberscope examination, usually at about 38  °C and usually it is transient.

8  Application of Endoscopic Techniques in Biliary Tract Surgery

Fever can be caused by the following factors, including improper disinfection of instruments, not strictly following aseptic technique, or excessive increase in pressure caused by physiological saline flushing into the biliary tree. Turbid bile after infection can be observed in the drainage tube. Usually, fever does not require special treatment; only with persistent bile drainage will fever subside. Intravenous antibiotics for severe infections are required. • Sinus Perforation When a fibercholedochoscope is inserted into the sinus and pushed forward and does not enter the biliary tract. Instead, it enters a “cavity” without red granulation tissue as the wall, with a dimly lit space. When the mirror is continuously pushed forward, the pink appearance of the small intestine can be observed. At the same time, the sinus outflow is a reddish liquid, without bile, which confirms that the choledochoscope entered the abdominal cavity through the perforated sinus. Sinus perforation is often caused by premature postoperative fiberoptic choledochoscopy, rough operation of the choledochoscope, and blind endoscopy without sinus orifice. Therefore, fibercholedochoscopy or lithotomy must be performed at least 6  weeks after surgery, not beforehand. If the patient is weak and recovers slowly, the stone removal should be postponed appropriately because the sinus will not be strong enough. Otherwise, an excessively thin sinus tract can be easily perforated. Fiberoptic choledochoscopes should be operated gently. Only when the small hole in the sinus tract is observed can the mirror be slowly inserted, which is important to avoid perforating the sinus. • Sinus fracture When larger stones are removed by fibercholedochoscope, the small opening of the sinus may not be found when the choledochoscope is reinserted so that the choledochoscope cannot be inserted into the biliary tract and enters the abdominal cavity, and the small pink intestine appears in the field of vision. In the course of pulling the large stone out of the sinus, the surgeon exerted too much force, and the assistant did not press the skin around the ostium with his hand. Other issues such as early stone removal, old and weak patients, or a weak sinus tract, can lead to sinus rupture. The stone removal time should not be too early. When the surgeon pulls out a large stone, the assistant should press the skin around the sinus ostium to prevent the sinus from being broken. • Hemobilia Fiberoptic choledochoscopy and lithotomy can reveal hyperemia and edema of the bile duct mucosa, erosion, and even ulceration. The diseased bile duct has blood clots, a reddish fluid fills the field of vision, and bleeds are visible after rinsing, similar to a fluttering red ribbon. Situations which may precipitate this condition include: Cholangitis in the bile duct due to stones, or even

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ulcers in the mucus membrane of the duct; pulling out larger stones may lead to varying degrees of bleeding, poor liver function, and abnormal clotting times. Prevention: (a) the operation of fibercholedochoscope should be gentle; (b) the patient’s liver function should be treated and protected with antibiotics, and stones should not be taken until the patient’s biliary tract infection has subsided and liver function is normal; (c) the vast majority of patients with biliary tract hemorrhage do not require special treatment, and hemostasis can be obtained by irrigation of the bile duct with a solution made by adding 0.5  mg of adrenaline to 500  ml of normal saline. If hemostasis fails, microwaves can be used to stop bleeding delivered with a fiberoptic choledochoscope. • Tear in the bile duct Fibercholedochoscopy shows a fissure at the opening of the diseased bile duct, and bleeding and blood clots in the biliary fissure. Possible reasons include: (a) The bile duct opening is narrow; when larger stones in the dilated bile duct are removed, a rough operation may lead to tear in the bile duct; (b) in some cases, the conventional operation of advancing while observing directly under fiberoptic choledochoscope is neglected; severe complication caused by a bile duct tear may also occur if the operation of fibrocholedochoscopy is excessively dependent on X-ray fluoroscopy. Prevention: The operation of the fibrocholedochoscopy should be gentle, without too much force, and should be advanced while observing the lens; fiberoptic choledochoscopy must be stopped once the bile duct tear occurs, and biliary bleeding can be prevented by normal saline flush (500  ml of saline +0.5 ml of adrenaline); T-tube drainage should be replaced, and intravenous antibiotics should be given for several days. After 2  ~  3  weeks, fibrocholedochoscopy can be performed. • Diarrhea After choledochofiberscope examination, diarrhea, watery stool, no mucus, and no blood observed. Possible cause: the perfusion of physiological saline during choledochofiberscopy was excessive (more than 3000 ml). Prevention: during each choledochofiberscope examination, the physiological saline should not exceed 3000 ml; no special treatment is needed for diarrhea. • Acute Pancreatitis Symptoms such as abdominal pain, fever, abdominal distension occur. Blood and urine amylase levels increase. Possible reasons: when stones are taken through the choledochoscopy, especially the stones embedded in the ventral ampulla of Vater, local injury may occur, leading to inflammation, edema, and pancreatic juice obstruction, which may cause pancreatitis. Prevention: actions to mitigate and keep occurrence to a minimum include: assuring appropriate cleaning, disinfection, and aseptic technique of the device, careful control of saline infusion pressure to prevent excessive pressure, review of the stone removal

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procedure. Prevention: Strengthen the disinfection and aseptic technique of the device. The pressure of saline infusion should not be excessive. Check the stone removal operation. If acute pancreatitis arises during the procedure, keep the T tube circulated smoothly, strengthen the antibiotics, relieve pain, relieve spasm, and inhibit pancreatic secretion, and most of them can be cured. • Nausea and Vomiting Symptoms of nausea and vomiting related to the treatment of fiberoptic choledochoscopy can occur after surgery. Possible reasons: the stimulation of intrahepatic bile duct or the opening of the dilated Oddi sphincter by fiberoptic choledochoscopy; excessive pressure of saline infusion. Prevention: The treatment of fiber choledochoscopy should be gentle, and the pressure of saline should not be too high. When symptoms of nausea and vomiting occur, intramuscular injection of metoclopramide can be performed.

8.4

Capsule Endoscopy

Capsule endoscopy, also known as wireless endoscopy, is a high-tech product developed and produced in Israel around the turn of the century. The capsule, which contains a tiny camera, light source, battery, and transmitter, is similar in shape to a large vitamin pill. After a patient swallows the capsule, a tiny wireless camera inside moves naturally through the gastrointestinal tract taking thousands of pictures that are transmitted to a recording device carried by the patient. The imaging data of the small intestine can be obtained without pain. Capsule endoscopy is prominent in the diagnosis of unknown gastrointestinal bleeding and small intestine disease, so it is a great advance both technically and clinically. Also, the advantages of simple operation, no complication, and no need for hospitalization are undoubtedly a significant progress in the history of diagnosing small intestine diseases. Capsule endoscopy will replace the application of propulsive enteroscopy in the diagnosis of small intestine diseases and become the first choice for patients with suspected small intestine disease after gastroscopy and colonoscopy (Table 8.1). The main complication of capsule endoscopy is the risk that the capsule does not pass through the intestine smoothly. Capsule staying in the digestive tract for 2 weeks or more is defined as capsule retention, requiring medication, endoscopic, or surgical intervention. The incidence of retention is associated with underlying diseases, including Crohn’s disease, intestinal stenosis caused by nonsteroidal anti-inflammatory drugs (NSAID), radiation enteritis, and small bowel tumors. Even in the healthy small intestine, the occurrence of retention cannot be avoided entirely.

Table 8.1  Indications and contraindications of capsule endoscopy Indications Gastrointestinal bleeding of unknown origin Hypoferric anemia Crohn’s disease Intestinal tumor NSAID-induced enteropathy Portal hypertensive enteropathy Celiac disease Hereditary polyposis syndrome Functional abdominal pain

8.5

Contraindications Absolute contraindication Clinical or radiographic features of ileus Extensive and acute Crohn’s disease with obstruction Intestinal pseudo-obstruction Relative contraindication Cardiac implantable electronic devices such as pacemakers Dysphagia A history of prior abdominal or pelvic surgery Pregnancy Extensive diverticulosis

Laparoscope

In April 1991, Gou Zuwu of the Second People’s Hospital of Qujing, Yunnan Province, successfully performed the first laparoscopic cholecystectomy independently in China, marking the beginning of the development of laparoscopic surgery in mainland China. The laparoscopic technique is most suitable for the treatment of certain benign diseases and early tumors, such as fenestration of hepatic cysts, resection of large intestinal tumors, repair of the gastric fold of esophageal hiatus hernia, repair of abdominal hernia, removal of gastric leiomyoma, gastrointestinal cancer, gastrointestinal perforation repair, the release of adhesive intestinal obstruction; moreover, diseases such as thyroid, breast, lower extremity varicose veins, various causes of hypersplenism splenectomy, and other diseases can be treated with minimally invasive treatment, and the effect is significant. In recent years, laparoscopic surgery is progressing to a higher field, and the indications for surgery are expanding to the treatment of diseases in various systems. Trauma is diminishing. Surgery has experienced the transition from traditional laparotomy to minimally invasive laparoscopic surgery. Now, it is developing from porous laparoscopic surgery to single-port laparoscopic surgery (SPLS). At present, the primary single-port surgery is transumbilical single-port laparoscopic surgery. Natural orifice transumbilical surgery (NOTUS) is a transumbilical punctured tube with multiple operating channels. The operation is performed by placing the surgical instrument through the operation channel, and the specimen is removed through the umbilicus. The surgical incision is located in the umbilical cord. The skin fold of the umbilical cord can cover the incision and achieve a satisfactory cosmetic effect. In the age of scientific and technological explosion, the single-port laparoscopic technique brought about by the leap of surgical technology is still in the exploratory stage. However, it has

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definite advantages: scarless, enhanced cosmetic effect, and reduced incision to reduce postoperative pain. Faster recovery reduces the chance of herniation and infection.

8.6

Endoscopic Ultrasound

Endoscopic ultrasound (EUS) is a combination of endoscopy and ultrasound for gastrointestinal tract examination. The miniature high-frequency ultrasonic probe is placed at the top of the endoscope. When the endoscope is inserted into the body cavity, the pathological changes of digestive tract mucosa are observed directly through the endoscope. The real-time scanning of EUS examination can be used to obtain the histological features of the gastrointestinal hierarchy and surrounding structures; thus, further improving the diagnostic level of endoscopy and ultrasound. The exploration of biliary tract diseases can be completed by longitudinal EUS and circumferential EUS.  Longitudinal EUS is particularly suitable for exploring the relationship between the distal common bile duct and ampulla, and for judging the nature of pancreatic masses. Based on endoscopic retrograde cholangiography (ERC), intraductal ultrasonography (IDUS) is performed with small probe ultrasound, which has some advantages in detecting hepatic hilar cholangiopathy. The fine-needle puncture (endoscopic ultrasound-guided fine-­ needle aspiration, EUS-FNA) guided by longitudinal EUS can be used to obtain the cellular and/or histopathological diagnosis of biliary space-occupying lesions. The diagnostic sensitivity and accuracy are superior to traditional methods. The application of a series of new functions and techniques such as harmonic contrast ultrasound elastic imaging and 3D ultrasound imaging will further improve the role of EUS in the diagnosis of benign and malignant biliary tract diseases. Under EUS, malignant pancreatic tumors appear as hypoechoic areas with blurred borders, scattered calcifications and liquefaction areas, compression of the peritoneal pancreatic duct, or interruption of the wall echoes or solid echoes in the pancreatic duct, and dilatation of the pancreatic duct at the distal end of the tumor. When the adjacent organs are infiltrated, the serous layer of adjacent organs is broken; the echo layer of the wall of the vessel is interrupted when the blood vessel is infiltrated. When the tube is infiltrated, the dilated bile duct is interrupted, and the lymph nodes around the pancreas are enlarged. EUS-FNA can provide a relatively accurate pathological and cytological diagnoses, avoiding the use of traumatic tissue diagnostics such as diagnostic laparoscopy. The latest linear scan endoscopic ultrasonography (LSE) can be used for real-time ultrasound-guided puncture biopsy with a 19-22G puncture needle to obtain a more rapid and accurate cytological diagnosis. In addition to cytological specimens,

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histopathological specimens can be obtained by using cutting needles with larger inner diameter. The clinical observation showed that the sensitivity and specificity of EUS-FNA in the diagnosis of solid pancreatic tumor were very high, and the operation was safe. The complication rate was less than 1%. For some patients, enhanced scanning or elastography guided by endoscopic ultrasound can also be used to confirm the diagnosis.

8.6.1 E  US-Guided Biliary Drainage through the Transduodenal Route Biliary drainage under ERCP is an established technique for biliary obstruction secondary to pancreatic head malignancies. However, if ERCP fails, EUS-guided biliary drainage (EUS-BD) through the transduodenal approach can be used as an alternative drainage technique (Figs. 8.3, 8.4, and 8.5).

8.6.2 E  US-Guided Radioactive Seed Implantation in Pancreatic Cancer The parameters of an iodine-125 seed were as follows: activity 0.40  ~  0.50  mCi, with a half-life of 60.1  days, a mean photon energy of 27–35 keV γ-ray, and penetration distance in the human tissue of only 1.7 cm. The implanted iodine-125 seeds can generate a high dose within the tumor tissue, which

Fig. 8.3  MRCP suggests dilated bile duct

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8.7

Fig. 8.4  Endoscopic ultrasonography-guided puncture

3D Visualization-Assisted Endoscopic Technology

In 2001, the 3D visualization system became used to clearly show the location, the shape, the size, and the number of the stones; the spatial position and extent of the bile duct stenosis are also represented accurately. 3D-assisted endoscopy is of great significance for the classification, diagnosis, and surgical guidance of hepatolithiasis. The combination of 3D visualization systems and traditional endoscopic techniques in biliary surgical diseases, especially biliary calculi, has fully utilized the advantages of precise diagnosis and treatment and minimally invasive treatment, and effectively improved the therapeutic effect. Percutaneous transhepatic choledochoscopy (PTCS): The sinus tract is dilated once a week after percutaneous transhepatic biliary drainage (PTBD), and then expanded to 16F in two weeks in order to perform fiber choledochoscopy. Extraction of stone through dilated sinus tract is a method with a long cycle and high frequency of dilatation, and patients experience a higher incidence of bleeding, bile leakage, cholangitis, and peritonitis, postoperatively. It has been reported in the literature that the complication rates following PTCS range from 9% to 26% (Weber et al. 2009; Li et  al. 2015; Inamdar et  al. 2016). By preoperative MI-3DVS, the time of percutaneous transhepatic biliary drainage fistula for percutaneous transhepatic cholangioscopic lithotomy (PTCSL) can be optimized. Animal studies have shown that the wall of percutaneous hepatic fistula, intramural vascular embolization, fibrous tissue hyperplasia, and adhesion between the hepatic surface around the fistula and the thoracic and abdominal wall are formed at 5 ~ 7 days after PTCD; at this time, lithotripsy after percutaneous hepatic dilatation (Figs.  8.6, 8.7, 8.8, and 8.9) is relatively

Fig. 8.5  Endoscopic ultrasonography-guided drainage

is sufficient to kill tumor cells and achieve good clinical effect in the treatment of advanced pancreatic cancer. Compared with traditional surgical implantation of radioactive particles for pancreatic cancer, EUS-guided iodine 125I implantation in pancreatic cancer appears to be a safer and more effective minimally invasive technique for the management of pancreatic cancer.

Fig. 8.6  B-mode ultrasonography positioning

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Fig. 8.7  Dilated bile duct puncture and bile extract Fig. 8.9  Indwelling of 8F drainage tube

8.8

Fig. 8.8  Dilated sinus tract

safe. Because intrahepatic cholelithiasis is often accompanied by various degrees of obstruction, the pressure in the dilated bile duct is high. The drainage of bile reduces the internal pressure of bile duct, bacteria, and inflammation in the bile duct; it also improves liver function, repairing the damaged bile blood barrier. Only after the expansion of the fistula lithotripsy can the incidence of complications be reduced. Based on this procedure, the other channel time can be established. MI-3DVS is used to simulate puncture and ostomy repeatedly, avoiding important blood vessels such as a thoracic cavity, celiac intestine, hepatic artery, portal vein, and hepatic vein. Percutaneous liver lithotripsy at stage I was performed in patients with or without a history of biliary tract surgery. Sixteen cases of lithotripsy at stage I and 23 cases of lithotripsy at stage II were successfully performed, respectively.

Endoscopic Diagnosis and Management of Hepatobiliary and Pancreatic Diseases

Combined endoscopic treatment refers to the use of two or three minimally invasive techniques such as laparoscope, choledochoscope, and duodenoscope in the simultaneous or sequential diagnosis and treatment of cholelithiasis. This strategy can make up for the limitations and shortcomings of a single method, avoid their respective shortcomings, and aggregate their respective advantages. Multi-endoscopies combined with minimally invasive treatment for cholelithiasis has become increasingly mature, forming a combined minimally invasive treatment system based on laparoscopy, digestive endoscopy, choledochoscopy, etc. The clinical application has shown that the minimally invasive treatment of cholelithiasis with multiple endoscopies is superior to the traditional surgical treatment or the minimally invasive treatment alone.

8.8.1 Laparoscopy Combined with Choledochoscopy The preoperative preparation, patient positioning, and the operating orifice of the abdominal wall in laparoscopic choledochoscopy combined with choledochoscope for the treatment of cholelithiasis are similar to that of conventional laparoscopic cholecystectomy. Laparoscopic cholecystectomy is usually performed first, followed by laparoscopic biliary exploration. If the diameter of the cystic duct is relatively thick, a choledochoscope can be inserted into the

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cystic duct for biliary exploration. If the cystic duct is thin, the anterior wall of the common bile duct is separated and exposed. After puncture confirmation, the common bile duct is cut along the longitudinal axis of the common bile duct. The common bile duct can also be cut through the stump of the cystic duct. Usually, the choledochoscopy enters the proximal bile duct from the right anterior axillary foramen and enters the distal bile duct from the inferior hilar foramen. The proximal bile duct stones should be removed first and then the distal bile duct stones. For those with residual stones in the intrahepatic bile duct but the lower end of the common bile duct is unobstructed, the T-tube is placed for drainage; which is extracted from the right central line of the clavicle through the subcostal foramen for postoperative angiography and lithotomy. For cholelithiasis complicated with intrahepatic bile duct stricture or duodenal papillary stenosis, balloon dilatation with laparoscopy, and a choledochoscope is feasible. The common hepatic duct is cut close to the narrow side and observe “head on” the opening of the hepatic duct. The curved forceps are expanded slightly, and the zebra guidewire is inserted into the intrahepatic bile duct at a certain depth, and the balloon is dilated along the guidewire to dilate the stenosis of the hepatic duct branches I and II. For patients with duodenal papillary stenosis, the balloon can be guided into the duodenal cavity by a guidewire, and the balloon is pulled back into the bile duct for 2 cm, then the pressure pump is attached to the balloon, and the catheter expanded with water injection. Laparoscopy combined with choledochoscopy is suitable for primary and secondary cholelithiasis when the diameter of choledocholithiasis is more than 1.0 cm. Patients with a large number of intrahepatic bile duct stones without absolute stricture of intrahepatic bile duct and whose Oddi sphincter function is excellent; when the incision of duodenal diverticulum and paradiverticular papilla are difficult with duodenal endoscopy; Mirizzi syndrome and elderly patients, patients who cannot tolerate multiple endoscopy treatments.

8.8.2 Laparoscopy Combined with Duodenoscopy Laparoscopy, combined with duodenoscopy in the treatment of biliary stones, can also be sequential. However, as for which one is better, opinions are diverse. Most scholars advocate two stages, especially for those with biliary pancreatitis and obstructive cholangitis. First, endoscopic retrograde cholangiopancreatography (ERCP) is performed to determine the distribution, number, size, and bile duct lesions of the stones. Then endoscopic sphincterotomy (EST) or endoscopic papillary balloon dilation (EPBD) is performed to remove the stones with a net basket and balloon. Stones with a diameter of less than 5 mm are treated with EPBD,

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followed by net basket extraction or balloon lithotomy without EST, to avoid papillary incision and complications and to preserve the integrity of the nipple and sphincter function. For stones with a diameter of 1–2 cm, especially for those with a hard-papillary texture and inflammatory stenosis, the EST is performed, and the incision direction is controlled within the fan-shaped range of 11–2 o’clock. The main incision is a mid-incision, which can retain 50% of the basic sphincter pressure. Stones with a diameter of more than 2  cm are treated by plasma-hydraulic lithotripsy or holmium laser lithotripsy, and then removed by a net basket and balloon. Usually, bile duct stones are removed under duodenoscope, and LC should be performed after pancreatitis and cholangitis are obviously alleviated or subsided. This combined method is suitable for patients with choledocholithiasis, suspected choledocholithiasis or duodenal papillitis, duodenal papillary stenosis, and biliary pancreatitis caused by it, as well as obstructive cholangitis.

8.8.3 Choledochoscopy Combined with Duodenoscopy Choledochoscopy combined with duodenoscopy, is mainly used for patients with residual stones after biliary tract recurrence. Residual stones less than 0.7 cm in diameter are removed through the T-tube sinus choledochoscopy by the stone basket. The patients with intrahepatic bile duct stones accompanied by stricture of the distal bile duct can be examined by choledochoscope, and then stones can be removed with a stone basket, biopsy forceps, anterior choledochoscope, and balloon catheter. Hard removal of stones with a diameter of more than 0.7 cm or larger irregular stones can lead to sinus injury. If the common bile duct is narrow and the stones are embedded in the lower part of the common bile duct, it is difficult to obtain the stone by choledochoscope alone. A choledochoscope can be used to push stones into the common bile duct and duodenal orifice under direct vision and then combined with lithotripsy and duodenoscopy, stones can be removed.

8.8.4 C  ombined Use of Duodenoscopy, Laparoscopy, and Choledochoscopy For complex cholelithiasis, which cannot be solved by one or two endoscopies, duodenoscopy, laparoscopy, and choledochoscopy can be used. Laparoscopy combined with choledochoscopy and duodenoscopy is also performed in two stages. ERCP is first performed to determine the size, number, and distribution of bile duct stones. If the stone is difficult to remove, endoscopic nasobiliary drainage tube (ENBD) or EST + ENBD should be performed. Laparoscopic

8  Application of Endoscopic Techniques in Biliary Tract Surgery

common bile duct exploration and choledochoscopic lithotripsy should be performed when the patient’s condition is improved. The placement of the ENBD tube under duodenoscopy is an essential step in three-mirror combined choledochotomy. Its functions include: improving the general condition of the patient, biliary decompression, and serving as a marker for choledocholithotomy during operation; as a biliary stent after an operation to drain bile and reduce the internal pressure of the biliary tract. The integrity and normal physiological function of the bile duct can be maintained with a T-tube during the operation. After the operation, cholangiography through the ENBD tube can be used to observe whether there are residual stones. Multi-mirror combined with minimally invasive therapy, has become the trend of clinical treatment of various surgical diseases and has a broad application prospect. With the improvement and innovation of minimally invasive devices and the popularization of minimally invasive concepts such as the application of robotic surgery systems, the difficulty of laparoscopic minimally invasive surgery has been dramatically reduced. The improvement and innovation, of endoscopic equipment and the combined application of endoscopic and other imaging techniques and treatment techniques, has greatly facilitated the diagnosis and treatment of biliary diseases. It is believed that more progress will be made in employing the combination of multiple endoscopes, and the expanding indications for use will benefit more patients with cholelithiasis.

References Bakes J.  Die choledochopapilloscopie nebst Bemerkungen und Hepaticus drainage und dilatation der Papilla. Arch f Klin Chir. 1923;126:473. Bozzini P. Lichtleiter, eine Erfindung zur Anschauung innerer Teile und Krankheiten, nebst der Abbildung. J Der Practischen Arzneykunde und Wundarzneykunst. 1806;24:107–24.

183 Cotton PB, Garrow DA, Gallagher J, et al. Risk factors for complications after ERCP: a multivariate analysis of 11,497 procedures over 12 years. Gastrointest Endosc. 2009;70:80–8. Elmunzer BJ.  Reducing the risk of post-endoscopic retrograde cholangiopancreatography pancreatitis. Dig Endosc. 2017;29(7): 749–57. ERCP Group, Chinese Society of Digestive Endoscopology; Biliopancreatic Group, Chinese Association of Gastroenterologist and Hepatologist; National Clinical Research Center for Digestive Diseases. Chinese guidelines for ERCP (2018). Zhonghua Nei Ke Za Zhi 2018;57(11):772–801. Fogel EL, Eversman D, Jamidar P, et al. Sphincter of Oddi dysfunction: pancreaticobiliary sphincterotomy with pancreatic stent placement has a lower rate of pancreatitis than biliary sphincterotomy alone. Endoscopy. 2002;34:280–5. Freeman ML, Nelson DB, Sherman S, et  al. Complications of endoscopic biliary sphincterotomy. N Engl J Med. 1996a;335:909–18. Freeman ML, Nelson DB, Sherman S, Haber GB, Herman ME, Dorsher PJ, et  al. Complications of endoscopic biliary sphincterotomy. N Engl J Med. 1996b;335:909–18. https://doi.org/10.1056/ NEJM199609263351301. Inamdar S, Slattery E, Bhalla R, et al. Comparison of adverse events for endoscopic vs percutaneous biliary drainage in the treatment of malignant biliary tract obstruction in an inpatient national cohort. JAMA Oncol. 2016;2:112–7. Lenriot JP, Le Neel JC, Hay JM, Jaeck D, Millat B, Fagniez PL.  Catheteisme retrograde et sphincterotomie endoscopique. Evaluation prospective en milieu chirurgical. Gastroenterol Clin Biol. 1993;17:244–50. Li M, Bai M, Qi X, et al. Percutaneous transhepatic biliary metal stent for malignant hilar obstruction: Results and predictive factors for efficacy in 159 patients from a single center. Cardiovasc Intervent Radiol. 2015;38:709–21. Rustagi T, Jamidar PA. Endoscopic retrograde cholangiopancreatography related adverse events: general overview. Gastrointest Endosc Clin N Am. 2015;25:97–106. Talukdar R. Complications of ERCP. Best Pract Res Clin Gastroenterol. 2016;30:793–805. Vandervoort J, Soetikno RM, Tham TC, Wong RC, Ferrari AP Jr, Montes H, et  al. Risk factors for complications after performance of ERCP.  Gastrointest Endosc. 2002;56:652–6. https://doi. org/10.1016/S0016-­5107(02)70112-­0. Weber A, Gaa J, Rosca B, et al. Complications of percutaneous transhepatic biliary drainage in patients with dilated and nondilated intrahepatic bile ducts. Eur J Radiol. 2009;72:412–7.

9

Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts Chihua Fang, Jian Yang, and Xu Chang

9.1

Introduction

In the twenty-first century, primary research in biliary tract surgery has realized remarkable achievements with the tremendous advances of related sciences such as molecular biology, molecular genetics, medical imaging, and clinical anatomy. Issues including the prevention and treatment of ischemic biliary diseases after liver transplantation, and the important role of extrahepatic bile duct blood supply in the occurrence and prevention of biliary tract surgery diseases, are also emerging. Hepatic artery variation is high, and so it is vital to take advantage of 3D visualization technology, to identify and then protect the variant arteries during surgery. The incidence of biliary complications after liver transplantation ranges between 5% and 35% (Ayoub et  al. 2010; Balderramo et al. 2011), which is one of the main reasons leading to graft failure or even mortality. With the improvement of the methods and techniques for anastomosis in liver transplantation, the biliary complications caused by technical issues are decreasing, and ischemic-type biliary lesions (ITBL) are the primary type of biliary complications after liver transplantation. Among the various causes of biliary ischemia, the destruction of bile duct blood flow is significant. Notably, the occurrence of extrahepatic bile duct hemorrhage, traumatic bile duct stenosis, and biliary anastomotic fistula may be related to bile duct blood supply injury, so attention has been increasingly paid to the blood supply of the bile duct in hepatobiliary surgery.

C. Fang (*) · J. Yang Zhujiang Hospital, Southern Medical University, Guangzhou, China X. Chang Panyu District Hospital of Traditional Chinese Medicine, Guangzhou, China

9.2

 tudy on Blood Supply S of Extrahepatic Bile Ducts and Construction of Its 3D Visualization Platform

9.2.1 H  istorical Evolution of Researches on Blood Supply of Extrahepatic Bile Ducts Previous studies on the blood supply of extrahepatic bile ducts were mainly carried out on cadavers and animal models. In 1948, Shapiro and Robillard first described the arterial blood supply of the common and hepatic ducts with reference to the common duct injury and theorized that arterial injury may induce biliary stricture and thereby aggravate a biliary injury (Shapiro and Robillard 1948). Their theory has stimulated the attention of clinicians and anatomists. Park et al. (1999) observed 58 cases of cadaveric specimens and realized that the basic blood supply of the biliary tract was derived from two to five branches of the posterior duodenal or superior pancreaticoduodenal artery. They anastomosed with each other and eventually coincided with the branches of the right hepatic artery and the gallbladder artery, forming a vibrant vascular network around the bile duct. The blood supply sources differ for each segment of the biliary tract. In the hilar part, the bile duct and the first, the secondary hepatic duct are mainly supplied by the branches of the right hepatic artery and the cholecystic artery. The branches of the posterior duodenal artery and the superior pancreaticoduodenal artery were mainly distributed to the upper part of the duodenum of the common bile duct and the posterior and lower segments of the duodenum. In contrast, the branches of the proper hepatic artery were not the main nutrient vessels of the bile duct. Northover et al. (1980) observed the blood supply of the bile duct by scanning electron microscopy of microvascular resin casts. In addition to further confirming the conclusion of Park, they also found another critical source of bile duct blood supply from the superior mesenteric artery. Because it runs behind the

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_9

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portal vein, it is called the posterior portal vein artery, which is divided into type I and type II. The two marginal arteries were anastomosed to each other along the two sides of the bile duct before the branches of the nutrient arteries entered into the bile duct. According to their anatomical location, Northover named them 3 o’clock and 9 o’clock arteries. Chinese scholars (Fang 2014) used the surgical microscope to dissect and observe the blood supply arteries of the hepatobiliary duct. After measuring their external diameter and blood supply ratio, they pointed out that the blood supply of extrahepatic bile ducts has two distinct characteristics. One is essentially axial. The right hepatic artery above (the first hepatic hilum), and the retroduodenal artery below converge in the supraduodenal bile duct. About 60% of the blood supply to the supraduodenal bile duct runs upward from vessels below, whereas 38% runs downward from the right hepatic arteries and cystic duct artery (Terblanche et al. 1983). Thus, the second characteristic emerges. The primary source of blood supply in each segment of the extrahepatic bile duct is different, and the blood supply status is also quite different. The blood vessel plexus in the lower segment of the bile duct and the wall of the hilar bile duct are denser while the upper duodenal bile duct is sparse. The upper duodenal bile duct is also the critical site of biliary tract operation. Historically, animal models suggested that achieving good post-operative hepatic blood flow is essential to the reduction of biliary strictures (Cameron and Hou 1962). Most anastomotic strictures occur when the marginal arteries on both sides of the anastomosis are ligated, and the blood supply at the anastomotic site decreased to 30% of normal. Studies on bile duct blood supply over the past half-­ century have confirmed that the bile duct is nourished by the pericholangiovascular network formed by anastomosis of terminal branches of multiple pericholangiovascular branches rich in oxygen, such as a hepatic artery, gallbladder artery, posterior duodenal artery, superior pancreaticoduodenal artery, and superior mesenteric artery. The arterial arch at 3 and 9 o’clock on both sides of the biliary tract is the main branch of the biliary blood supply. The damage to the biliary blood supply is closely related to the occurrence of biliary stricture after biliary surgery.

9.2.2 C  onstructing 3D Visualization Platform of Extrahepatic Bile Duct Blood Supply Based on Submillimeter CT Data and Its Clinical Significance Although scholars at home and abroad used cadaveric perfused specimens to better display the source and distribution of extrahepatic bile duct blood supply in normal cadavers, and confirmed the common main blood supply arteries of extrahepatic bile duct and the anastomosis and direction of these blood supply arteries around the bile duct; the extrahepatic bile duct supply characteristically has multiple sources,

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complex distribution, and variation because the small arteries of extrahepatic bile duct are the end of the celiac arteries. The variation of the celiac artery is complicated, especially the high variation rate of the hepatic artery and gallbladder artery, and characteristically complex distribution and variation. Besides, there must be distortion in the information of the cadaveric cast specimen compared with the information of the living human body, and there may be variations in the blood supply of the extrahepatic bile duct under pathological conditions. It is vital to have a deep understanding of the characteristics of the blood supply and the distribution of extrahepatic bile ducts in healthy human beings and the pathological conditions of the biliary tract. It is possible to provide a precise individualized morphological basis for the rational selection of clinical biliary surgery schemes and the prevention of postoperative biliary complications. Therefore, it is crucial to solve the problem of how to obtain the three-­ dimensional display of extrahepatic bile duct blood supply in living human before the operation. The 64-slice spiral CT adopts the detector layer of 64 * 0.4  ~  0.625  mm, which is in the real sense submillimeter CT. Submillimeter CT angiography (CTA) can obtain high-­ quality three-dimensional reconstructed images because of its fast data acquisition, wide coverage, and isotropy. Compared with traditional digital subtraction angiography (DSA), it has become the least invasive new technique to observe human vascular anatomy. The clinical application and development of submillimeter CT and angiography make it possible to observe the blood supply of the extrahepatic bile duct gradually. However, the extrahepatic bile duct has no independent blood supply artery and is supplied by the terminal branch of the celiac artery. The image processing software provided by CT itself is unable to segment and extract a three-dimensional reconstruction of the blood supply arterioles of the extrahepatic bile duct through maximum density projection (MIP) or volume rendering (VR). Meanwhile, because of the particularity of biliary tract structure and physiological function, CT is not sufficiently sensitive to display the bile duct system, and it is difficult to achieve ideal imaging of the bile duct system under non-­invasive conditions. Also, the 3D reconstruction function of CT has the following shortcomings in displaying 3D ­anatomical structure of extrahepatic bile duct and its blood supply: • The organs in arterial phase, venous phase, and portal phase cannot be registered simultaneously, which results in the difference of reconstruction quality. • The difference of interaction: the 3D reconstruction of CT machine must be operated by radiologists, which significantly restricts the clinician’s operations. • The 3D model generated from CT cannot be used in any combination, splitting, staining, transparency, and subsequent virtual operations in blood vessels, bile ducts, and other organs.

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

The rapid development of 3D visualization technology makes it possible to visualize the blood supply of the extrahepatic bile duct in the living human body. The reconstruction by computer, using three-dimensional image processing technology of the extrahepatic bile duct and blood supply, can not only solve the problem of distorted blood supply information of extrahepatic bile duct obtained from a cadaver, but also provide more realistic and accurate individualized anatomical guidance for clinical surgical procedures, which is of great significance for the design of a reasonable surgical mode and safe operation. Based on high-quality submillimeter CT data, a three-­ dimensional visualization model of the individualized extrahepatic bile duct and its blood supplying artery was successfully constructed using a proprietary MI-3DVS. Figure 9.1 is a 3D model of the extrahepatic bile duct blood supply in a patient undergoing choledochojejunostomy, clearly showing that after the gallbladder artery originates from the right hepatic artery, the main trunk moves close to the right side of the common hepatic duct and becomes part of the 9 o’clock artery supplying the bile duct. Then the anterior and posterior branches of the gallbladder artery are sent out in the neck of the gallbladder. According to the information provided by the 3D model, when the gallbladder is removed, the left side of the gallbladder neck is closed and the cystic artery is severed. Excessive separation of the common hepatic duct should be avoided, which can protect the 9 o’clock artery from injury. Meanwhile, the distance between the anterior and posterior branches of the main gallbladder artery and the right hepatic artery (Fig. 9.1) is measured in the 3D model to guide the position at which to disconnect the donor bile duct during the operation. While

Fig. 9.1  The distance between the anterior and posterior branches of the main cystic artery and the right hepatic artery was measured in the 3D model

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preserving the length of the extrahepatic bile duct, the blood supply of the common hepatic duct is preserved to the maximum extent, thus avoiding ischemic lesions of the bile duct caused by the postoperative destruction of the blood circulation of the bile duct. In the diagnosis and management of extrahepatic bile duct hemorrhage, it is necessary to deal with the anatomical characteristics of biliary blood supply. A 3D model can accurately display the parts of the extrahepatic bile duct and its blood supply distribution, as well as the location of the extrahepatic bile duct hemorrhage, to guide the accurate ligation of the corresponding biliary blood supply artery. In the common bile duct exploration, the 3D model of the extrahepatic bile duct and its blood supply can show whether there is a transverse supply artery in the anterior wall of the extrahepatic bile duct, avoiding damage to the artery during bile duct incision, resulting in postoperative bile duct ischemic stenosis or complications such as bile leakage. In the jejunal anastomosis of the common bile duct, the 3D model can guide the site of anastomotic selection and avoid stenosis or bile leakage after ischemic choledochojejunostomy. In summary, the construction of a three-dimensional visualization platform for biliary blood supply has opened up a new path for safe implementation of biliary tract surgery, adequate protection of biliary blood supply, and effective prevention of ischemic biliary disease.

9.3

 D Modelling of Extrahepatic Bile 3 Duct Blood Supply Based on Submillimeter CT Data

9.3.1 S  ubmillimeter CT Scanning of Extrahepatic Bile Duct Blood Supply Due to individual differences in patients, it is difficult to obtain high quality submillimeter CT data by traditional experience value scanning (traditional fixed delay time method). In this study, the experimental injection (low dose pretest) was used to observe the dynamic changes of celiac trunk artery enhancement by pre-injection of a low-dose contrast agent with low mA scanning. The time–density curve was used to determine the peak time of the arterial phase enhancement. The optimal scanning delay time of the artery is displayed, and the vasculature obtained by individualization is well developed, and the imaging features of the fine structure can be distinguished. The arterioles around the extrahepatic bile duct can be well developed, and the small branches can be developed more quickly than by the conventional method, thus satisfying the requirements of segmenting and 3D reconstruction of blood supply arteries of the extrahepatic bile ducts.

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Fig. 9.2  Submillimeter CT image, and the red arrow indicates the peripheral artery of the bile duct

From the collected data, the outlines of blood vessels and abdominal organs such as the pancreas, spleen, liver, and bile duct are clearly displayed, and the cross-section angiography agent is well filled.

9.3.1.1 Arterial Phase The peripheral artery of the extrahepatic bile duct is displayed (Fig.  9.2), which includes not only thicker vessels such as the common hepatic artery, the proper hepatic artery, the left and right hepatic artery, the gastroduodenal artery, the superior mesenteric artery, but also the finer vessels such as gallbladder artery, superior pancreaticoduodenal artery, and inferior pancreaticoduodenal artery. 9.3.1.2 Portal Venous Phase The portal venous system is well displayed, almost reaching the fourth-level branch of the portal vein. The contrast agent in the portal vein is well filled, and the boundary between the portal vein and hepatic parenchyma is clear.

9.3.2 N  ovel Interactive Segmentation Method Based on Volume Rendering Image segmentation is a critical technology in medical image processing and analysis. A medical image usually composed of region of interest (ROI) and backgrounds. The area of interest contains significant diagnostic information, which provides reliable bases for clinical diagnosis and pathological research; the ROI occupies a very small proportion of the total map area; however, the cost of misinterpretation is very high. Relatively, the information of the background region is less significant. Thus, it is critical to segment the medical image and extract the ROI. There are many traditional seg-

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mentation methods, which can be classified into three categories: threshold-based segmentation, edge-based segmentation, and region-based segmentation. Segmentation algorithms are generally based on two basic properties of gray level values: discontinuity and similarity. The pixels within the region usually have some similarities, while the pixels at the boundary between the regions generally have discontinuity. The most widely used segmentation method is region growing. It involves the selection of initial seed points on the CT tomographic image and determination of threshold values. The pixel values of the sequence maps within the threshold and the regions are segmented, and the three-­ dimensional reconstruction is performed. In image segmentation “dimensions” are not up down forward back type dimensions, but mathematically similar pixel values. Region growing uses formulae to decide similar pixels belong to one group not the neighboring group and form a “segment” (shape), you might have 5 types of tissue with definable image properties, If you are trying to segment them you could end up with very fractured images. The arteries that supply the extrahepatic bile duct are all terminal vessels with a small caliber. How to extract and segment them from CT data is a difficult problem. There are two existing methods for the reconstruction of segmented 3D medical images: surface rendering (SR) and volume rendering (VR). The VR technique involves several rays passing through 3D volume data, without the need of going through an intermediate surface extraction, and many details of voxels can be preserved. VR can reproduce the real structure of the human anatomy more effectively and improve the fidelity of results. VR is superior to SR in terms of image quality; however, SR is better than VR in terms of interaction performance and algorithm efficiency, at least on the current hardware platform. Since the VR algorithm is computationally intensive, its interactive performance is not always optimum, even by using high-performance computers. This issue can be addressed by using the segmentation method based on volume rendering interaction. Firstly, the volume rendering reconstruction is carried out. By adjusting the window width and window position, the 3D image of the tissue of ­immediate interest is obtained, the 3D seed points are obtained directly on the volume rendering image, and the region growth algorithm is applied. The growth process is displayed on the volume rendering image; when growth stops, repairment can be carried out on the volume rendering 3D image by human– computer interaction. Especially for small blood vessels, local small blood vessels can be extracted by magnifying the fine blood vessels, extracting and segmenting the small blood vessels. This project enables tissue segmentation, especially more refined blood vessel segmentation, reaching the same resolution level as volume rendering. When the user is satisfied with the current segmentation results, the results can be saved immediately, and the 3D surface rendering and recon-

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struction can be carried out quickly, thus facilitating interactive operation of the subsequent 3D model. The interactive segmentation method based on volume rendering realizes the new concept of reconstruction first and then segmentation, which makes the segmentation process “visible,” and achieves the purpose of improving the accuracy and integrity of segmentation. This method is satisfactory for segmenting and extracting the arterioles of the extrahepatic bile duct in submillimeter CT images, which lays a solid foundation for the construction of a 3D visualization model and provides a novel method for the segmentation of fine human ducts. Therefore, the advantages of interactive image segmentation method based on volume rendering in delicate blood vessel segmentation extraction are as follows: • The selection of seed points is directly performed on volume rendered images, which is intuitive and accurate. • The segmentation process is controllable. The segmentation can be interrupted according to the growth process at any time. • The segmentation results can be repaired. If errors occur, seeds can be added or deleted to correct the results until satisfied. • The delicate parts can be amplified. The defect where the original segmentation software cannot segment the micro parts can be corrected. Make full use of the information obtained by the imaging equipment.

Fig. 9.3  Branches of the hepatic artery. 1. Cystic artery; 2. Right hepatic artery; 3. Left hepatic artery; 4. Proper hepatic artery; 5. Common hepatic artery; 6. Gastroduodenal artery; 7. Superior posterior pancreaticoduodenal artery; 8. Anterior pancreaticoduodenal artery

9.3.3 3  D Modelling and Digital Classification of Blood Supply of the Extrahepatic Biliary Tract 9.3.3.1 3D Modelling of Blood Supply of the Extrahepatic Biliary Tract The 3D modelling of the extrahepatic bile duct and its supplying artery was performed by volume rendering with an interactive segmentation algorithm. The reconstructed model has a strong stereoscopic sense and truly reflects the 3D anatomical structure of individual extrahepatic bile duct and blood supply artery. The 3D model of the celiac artery can accurately display the 4 to 5-grade branches of the hepatic artery, the 2-grade branches of gallbladder artery (Fig. 9.3), pancreaticoduodenal artery arch (Fig. 9.4) and posterior portal vein (Fig. 9.5). The 3D model of the bile duct can clearly show the intrahepatic bile duct, left and right hepatic duct, gallbladder, common hepatic duct, choledochus and its dilatation, stricture, stone, or tumor. Meanwhile, the 3D model can be fused, split, magnified, reduced, rotated, and distance measured. Each part of the bile duct and its blood supply structure can be displayed individually or in combination through transparency and color settings.

Fig. 9.4  Pancreatic duodenal arterial arch

9.3.3.2 3D Characteristics of Extrahepatic Bile Duct Supplying Arteries The extrahepatic bile duct can be divided into upper and lower segments according to the region where the cystic duct flows into the extrahepatic bile duct. By observing and analyzing the origin, course, and distribution of extrahepatic bile duct blood supply arteries in the 3D model, the following characteristics can be seen. 3D Characteristics of Blood Supply to the Upper Extrahepatic Bile Duct Blood Supply of Right Hepatic Artery  The 3D model showed that the right hepatic artery originated from the

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Fig. 9.5  Yellow arrowhead points to the posterior portal artery (posterior view)

Fig. 9.7  Extrahepatic bile duct is supplied by the upper segment of left hepatic artery

Fig. 9.6  Superior extrahepatic bile duct is supplied by right hepatic artery

Fig. 9.8  Superior extrahepatic bile duct is supplied by the proper hepatic artery

proper hepatic artery and ascended along the left posterior part of the upper extrahepatic bile duct, then turned to the right posterior part of the common hepatic duct to enter the liver. Along the way, branches were issued in front of the bile duct to supply the upper extrahepatic bile duct (Fig. 9.6).

Left Hepatic Artery Supply  The 3D model showed that the left hepatic artery originated from the proper hepatic artery issued a branch in front of the bile duct and became the upper extrahepatic bile duct supplying artery (Fig. 9.7).

Cystic Artery Supply  The 3D model showed that after the cystic artery was issued from the right hepatic artery, its main trunk closely followed the right side of the common hepatic duct and became a part of the 9 o’clock artery supplying the upper extrahepatic bile duct. Then, the anterior and posterior branches of the cystic artery emanated from the neck of the gallbladder.

Proper Hepatic Artery Supply  The 3D model showed that the proper hepatic artery was close to the left wall of the extrahepatic bile duct and became the middle and upper extrahepatic bile duct supplying artery (Fig. 9.8). 3D Characteristics of Blood Supply to the Lower Extrahepatic Bile Duct Superior Pancreaticoduodenal Artery Supply  The 3D model showed that the superior and posterior pancreatico-

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

duodenal artery originated from the gastroduodenal artery, and then coursed along the left upper anterior direction of the lower extrahepatic bile duct; afterward, it becomes the inferior extrahepatic bile duct blood supplying artery (Fig. 9.9a). The posterior pancreaticoduodenal artery arch was formed behind the bile duct (Fig. 9.9b).

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9.3.3.3 3D Digital Classification of Blood Supply to the Extrahepatic Bile Duct The 3D digital classification of extrahepatic bile duct blood supply was established according to the characteristics of the source and distribution of extrahepatic bile duct blood supply in the 3D visualization model.

Cystic Artery Supply  The 3D model showed that the variant cystic artery was originated from the gastroduodenal artery and ran close to the right wall of the extrahepatic bile duct. It accompanied the cystic duct running under the duct and entered the gallbladder, forming the ascending 9 o’clock artery, which became the blood supply artery of the lower extrahepatic bile duct. Gastroduodenal Artery Supply  The 3D model showed that the gastroduodenal artery was close to the left wall of the lower segment of the extrahepatic bile duct and descended. Close to the wall of the bile duct, it issued the superior and posterior pancreaticoduodenal arteries and course down to right posterior inferior part of the bile duct to form the blood supply arteries of the lower extrahepatic bile duct (Fig. 9.10). Posterior Portal Vein Arterial Supply  After the posterior portal vein artery is originated from the superior mesenteric artery, it runs to the right along the direction of the portal vein and the back of the pancreatic head, and then up to the right posterior wall of the bile duct. After the combination with the posterior duodenal artery, it continues to adhere to the lower bile duct and runs upward, and mainly becomes the significant blood supply artery of the lower extrahepatic bile duct (Fig. 9.11).

a

Fig. 9.10  The lower segment of extrahepatic bile duct is supplied by gastroduodenal artery. 1. Cystic artery; 2. Gastroduodenal artery; 3. Superior posterior pancreaticoduodenal artery; 4. Posterior pancreaticoduodenal arch

b

Fig. 9.9  The lower extrahepatic bile duct is supplied by the superior posterior pancreaticoduodenal artery. (a) The front view; (b) The back view

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The Blood Supply of the Upper Extrahepatic Bile Duct Type I Right hepatic artery blood supply. Three subtypes were subdivided according to its combination with other arteries: Type IA Right hepatic artery only (Fig. 9.12). Type IB Right hepatic artery combined with gallbladder artery (Fig. 9.13). Type IC Right hepatic artery combined with the proper hepatic artery (Fig. 9.14). Type II Left hepatic artery combined with gallbladder artery blood supply (Fig. 9.15).

Fig. 9.11  Extrahepatic bile duct at lower segment of blood supply is supplied by the posterior portal artery (yellow arrows indicate posterior portal artery)

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Blood Supply of the Lower Extrahepatic Bile Duct Type I Superior and posterior pancreaticoduodenal artery blood supply. Three subtypes were subdivided according to their combination with other arteries: Type IA Superior and posterior pancreaticoduodenal artery only (Fig. 9.16). Type IB Superior and posterior pancreaticoduodenal artery combined with gastroduodenal artery (Fig. 9.17). Type IC Superior and posterior pancreaticoduodenal artery combined with posterior portal vein artery (Fig. 9.18). Type II Gastroduodenal artery and the blood supply type of its main branches (except the superior and posterior pancreaticoduodenal artery) (Fig. 9.19). Type III Blood supply of the gallbladder artery originated from the gastroduodenal artery (Fig. 9.20).

9.3.3.4 3D Modelling of Anastomotic Artery Around the Extrahepatic Bile Duct The incidence of hepatic artery variation is high, and the right hepatic artery is an important source of extrahepatic bile duct blood supply. It is of great clinical significance to identify and protect the variant hepatic artery during the operation. For example, the 3D model of extrahepatic bile duct blood supply showed that the variant right hepatic artery originated from the superior mesenteric artery; the posterior superior pancreaticoduodenal artery issued branches, and its branches were close to the common bile duct, and the left edge of the common hepatic duct and ran upward. Finally, they converged with the variant right hepatic artery to form the left marginal artery of the extrahepatic bile duct (3 o’clock artery) and supplied the extrahepatic bile duct throughout (Fig.  9.21). The significance of analyzing the variant extrahepatic blood supply artery by 3D technique lies b

Fig. 9.12  The superior extrahepatic bile duct is supplied by the right hepatic artery. The blue arrow indicates the branch of the right hepatic artery accompanying the extrahepatic bile duct. (a) Lateral, type IA; (b) Dorsal, type IA

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

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Fig. 9.13  The superior extrahepatic bile duct is supplied by the right hepatic artery and the gallbladder artery. (a) Ventral, type IB; (b) Dorsal, type IB

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Fig. 9.14  The superior extrahepatic bile duct is supplied by the right hepatic artery and proper hepatic artery. (a) Ventral, type IC; (b) Lateral, type IC Fig. 9.15  The superior extrahepatic bile duct is supplied by the left hepatic artery and cystic artery (type II)

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Fig. 9.16  The lower extrahepatic bile duct is supplied by the superior posterior pancreaticoduodenal artery. (a) Ventral, type IA; (b) Lateral, type IA

9.4

Fig. 9.17  The lower extrahepatic bile duct is supplied by superior posterior pancreaticoduodenal artery and gastroduodenal artery (type IB)

in this: If no variant right hepatic artery originated from a superior mesenteric artery is identified before pancreaticoduodenectomy, the common hepatic artery and branches of the hepatoduodenal ligament exist normally. It is easier to be neglected during intrahepatic exploration. If it is accidentally disconnected, it may cause extrahepatic bile duct ischemia in addition to hepatic complications, which may lead to the occurrence of cholangiointestinal anastomotic fistula, because right hepatic artery becomes the main blood supply artery of the residual extrahepatic bile duct after the gastroduodenal artery is disconnected.

 D Modelling of Extrahepatic Bile 3 Duct Blood Supply in Extrahepatic Biliary Obstructive Diseases

Extrahepatic biliary obstructive diseases are common in hepatobiliary surgery, including cholelithiasis, pancreatic head tumor or periampullary tumor, and inflammatory stenosis of the lower common bile duct. Surgical treatment is often required, such as common bile duct exploration, end-to-side or side-to-side anastomosis of the bile duct, and jejunum. Although the technique of surgical anastomosis is improving continuously, postoperative biliary mucus deposition, biliary tract or bile intestinal anastomotic stricture, and biliary ­fistula have been thorny complications of biliary surgery. In recent years, with the development of liver transplantation and anatomy as well as understanding of hepatic bile duct nutrient vessels, it is noted that the destruction of extrahepatic bile duct blood supply is closely related to the occurrence of these complications. By discussing the pathological relationship between biliary blood supply and biliary stricture and bile duct anastomotic fistula, some scholars have found that local ischemia caused by blocked blood supply can damage the bile mucosa and make it susceptible to infiltration of bile. The effect of bile on ischemic tissue in the wall leads to inflammation, edema, and fibrosis, resulting in the closure of the capillary plexus in the wall, further exacerbating the local ischemia and fibrosis of the wall. Both Cameron and Chung have confirmed through animal experiments that the destruction of biliary tract blood transport is

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Fig. 9.18 (a–b) The lower extrahepatic bile duct is supplied by the superior posterior pancreaticoduodenal artery and the posterior portal artery. Yellow arrow indicates the posterior portal vein artery, and the white indicates the superior posterior pancreaticoduodenal artery (type IC)

ply in patients with extrahepatic bile duct obstructive diseases, can be obtained to help carry out individualized preoperative planning and surgical design. This provides individualized anatomical guidance for the rational selection of clinical biliary surgical plans.

9.4.1 D  igital Classification of Extrahepatic Bile Duct Blood Supply for Obstructive Biliary Disease

Fig. 9.19  The gastroduodenal artery and its branch, anterior superior pancreaticoduodenal artery supply the lower extrahepatic bile duct, and form the anterior arch of the pancreaticoduodenal artery (type II)

the leading cause of postoperative biliary stricture and bile leakage. There is a consensus that delayed biliary stricture occurring in some patients after extrahepatic bile duct exploration is related to local compressive ischemic injury caused by T-tube coarsening and tight suture. Based on the 3D model, information such as the source, course, and distribution of extrahepatic bile duct blood sup-

Three-dimensional visualization and digital typing of extrahepatic bile duct blood supply were carried out in 41 patients with extrahepatic bile duct obstructive disease (Yang 2017). Inclusion criteria: extrahepatic bile duct dilatation (diameter larger than 10 mm), the indication of biliary tract operation, common bile duct exploration, choledochojejunostomy, etc. Exclusion criteria: previous abdominal surgery history, changes in the extrahepatic bile duct and its adjacent anatomical structures. The mean diameter of the extrahepatic bile duct 24.3  ±  5.1  mm (range 16–34  mm). Clinical diagnosis: 15 cases of choledocholithiasis (including lower common bile duct stones, intrahepatic and extrahepatic bile duct stones), 5 cases of lower biliary tract inflammatory stenosis, 21 cases of pancreatic head or periampullary tumor. All patients underwent 64-slice spiral CT angiography (CTA) scan of the upper abdomen before the operation, and the extrahepatic bile duct blood supply and its adjacent organs and blood vessels were reconstructed by the abdominal medical image

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Fig. 9.20 (a–b) The cystic artery originated from gastroduodenal artery supplies the lower extrahepatic bile duct (type III)

Table 9.1  Incidence of digital extrahepatic bile duct supplying artery (Yang 2017) Types Right hepatic artery Superior posterior pancreaticoduodenal artery and its branches Cystic artery Proper hepatic artery Gastroduodenal artery and its main branchesa Left hepatic artery Posterior portal artery (from celiac trunk) Posterior portal artery (from superior mesenteric artery) Other arteries

N 35 30

Incidence (%) 85.4 73.2

27 12 7

65.9 29.3 17.1

6 2 2

14.6 4.9 4.9

1

2.4

The superior posterior pancreaticoduodenal artery is not included

a

Fig. 9.21  Anastomotic artery forming around the extrahepatic bile duct

duct blood supply. Meanwhile, it can show the stereoscopic anatomical relationship between bile duct stones, tumors and surrounding organs and blood vessels.

three-dimensional visualization system (MI-3DVS). A total of 41 thin layer (0.625 mm) DICOM images were collected from four stages of CT, including plain scan, arterial phase, portal phase, and venous phase, with excellent image quality, as well as a clear display of peripheral blood supply artery of the extrahepatic bile duct, cholelithiasis, pancreatic and periampullary lesions, abdominal organs, and portal vein. The 3D model of extrahepatic bile duct blood supply established by MI-3DVS can obtain dynamic images of full dimension rotation, which can be arbitrarily scaled, displayed by any combination, and can be opacified or hidden from the target organ model, showing clearly the origin of extrahepatic bile

9.4.1.1 Distribution of Extrahepatic Bile Duct Blood Supply The right hepatic artery was involved in the blood supply in 35 cases (85.4%), the superior pancreaticoduodenal artery and its main branches in 30 cases (73.2%), the gallbladder artery in 27 cases (65.9%), the proper hepatic artery in 12 cases (29.3%), the gastroduodenum and its main branches in 7 cases (17.1%), the left hepatic artery in 6 cases (14.6%), the posterior portal vein artery in 4 cases (9.8%) and the other arteries in 1 case (2.4%) (Table 9.1). It can be seen that the extrahepatic bile duct has a reticular blood supply formed by multiple arteries (Yang 2017).

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

9.4.1.2 Digital Classification of Extrahepatic Bile Duct Blood Supply Among the 41 cases (Yang 2017) of the upper extrahepatic bile duct blood supply, there were 6 cases of type IA (14.6%) (Fig. 9.22), 17 cases of type IB (41.5%) (Fig. 9.23), 12 cases of type IC (29.3%) (Fig. 9.24), and 6 cases of type II (14.6%) (Fig. 9.25) (Table 9.2). In the lower extrahepatic bile duct blood supply, there were 13 cases of type IA (31.7%) (Fig.  9.26), 13 cases of type IB (31.7%) (Fig.  9.27), 4 cases of type IC (9.8%)

(Fig. 9.28), 7 cases of type II (170%) (Fig. 9.29), 4 cases of type III (9.8%) (Fig. 9.30) (Table 9.3).

9.4.2 S  urgical Management Based on 3D Modelling of Extrahepatic Bile Duct Blood Supply All the 41 cases underwent surgical treatment, including choledocholithotomy in 15 cases (3 cases of left extrahepatic

b

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Fig. 9.22  Blood supply to the upper extrahepatic bile duct (type IA). (a) The right hepatic artery supplies the upper extrahepatic bile duct. The blue arrow indicates the branch of the right hepatic artery accom-

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panying the extrahepatic bile duct; (b) The right hepatic artery supplies the upper extrahepatic bile duct. The blue arrow indicates the branch of the right hepatic artery accompanying the extrahepatic bile duct.

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Fig. 9.23  Blood supply to the upper extrahepatic bile duct (type IB). (a) The superior extrahepatic bile duct is supplied by the right hepatic artery and the gallbladder artery; (b) The superior extrahepatic bile duct is supplied by the right hepatic artery and the gallbladder artery

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b

Fig. 9.24  Blood supply to the upper extrahepatic bile duct (type IC). (a) The right hepatic artery and the proper hepatic artery supply the upper extrahepatic bile duct; (b) The right hepatic artery and the proper hepatic artery supply the upper extrahepatic bile duct

biliary tract operation was in accordance with the preoperative planning, and the coincidence rate was 100%. The intraoperative morphology of extrahepatic bile duct, the blood flow of extrahepatic bile duct, the variation of the hepatic artery, the distribution of stones, and the relationship between tumor and blood vessel (Fig. 9.31), were all consistent with the preoperative 3D model. Of the 41 cases, 3 had mild pancreatic leakage, 4 had a pulmonary infection, 2 had incision fat liquefaction. They recovered after active conservative treatment. No intraoperative or postoperative biliary bleeding or biliary fistula occurred in any patient. Patients were followed up between 3 and 15 months. No extrahepatic biliary stricture or biliary–intestinal anastomotic stricture occurred (Fig. 9.32). Fig. 9.25  Blood supply to the upper extrahepatic bile duct (type II). The left hepatic artery and the cystic artery supply the upper extrahepatic bile duct Table 9.2  Digital classification of the blood supply of the upper extrahepatic bile duct in 41 patients with biliary obstruction (Yang 2017) Types Type IA Type IB Type IC Type II

N 6 17 12 6

Incidence (%) 14.6 41.5 29.3 14.6

lobectomy), end-to-side cholangiojejunostomy in 22 cases (20 cases of pancreaticoduodenectomy), side-to-side Cholangiojejunostomy in 3 cases, and excision of solid pseudopapilloma in the head of the pancreas with duodenal preservation in 1 case (Yang 2017). The method of intraoperative

9.4.3 C  linical Significance of 3D Modelling of Extrahepatic Bile Duct Blood Supply in Patients with Biliary Obstruction 9.4.3.1 Digital Classification and Clinical Significance of Extrahepatic Bile Duct Blood Supply in Patients with Biliary Obstruction Digital classification of extrahepatic bile duct blood supply based on the distribution characteristics of blood supply to the upper and lower extrahepatic bile ducts, is helpful for clinicians to correctly diagnose the blood supply type of the extrahepatic bile duct in the upper and lower segments. Preoperative evaluation is performed according to the position of the extrahepatic bile duct, which guides the rationale for selecting the surgical method.

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Fig. 9.26  Blood supply of the lower extrahepatic bile duct (Type IA). (a) The posterior superior pancreaticoduodenal artery supplies the lower extrahepatic bile duct; (b) The posterior superior pancreaticoduodenal artery supplies the lower extrahepatic bile duct

Fig. 9.27  Blood supply of the lower extrahepatic bile duct (Type IB). The posterior superior pancreaticoduodenal artery and the gastroduodenal artery supply the lower extrahepatic bile duct

For example, in pancreatectomy with duodenal preservation, the site of operation is mainly in the lower part of the common bile duct, and the surgeon protects the duodenum and the lower extrahepatic bile duct blood supply by retaining the posterior pancreaticoduodenal arterial arch based on experience from autopsy. After complete resection of the lesions, the common bile duct is examined for ischemia. If the blood supply of the common bile duct is inadequate, the common bile duct should be cut off, and choledochoduodenal anastomosis should be performed. However, delayed postoperative biliary ischemia is often unnoticed, thus increasing the occurrence of biliary fistula and stricture. If

the digital classification of extrahepatic bile duct blood supply can be performed before operation, the operative method can be selected according to the type of classification. When the blood supply of the lower extrahepatic bile duct is classified as type I, it is mainly supplied by the superior posterior pancreaticoduodenal artery, whose arch should be preserved during operation. For type II, the main supply of bile duct was the gastroduodenal artery and pancreaticoduodenal anterior artery. It was often suggested that the posterior pancreaticoduodenal artery arch was small, and the anterior pancreaticoduodenal artery arch should be preserved to ensure the blood supply of duodenum and bile duct. If type III, the cholecystic artery originated from the gastroduodenal artery, goes up to the upper right, and supplies blood to the bile duct. It is necessary to avoid the destruction of the ascending gallbladder artery while preserving the head of the pancreatic artery arch; if the posterior pancreaticoduodenal artery arch is preserved only according to experience, it may lead to complications such as postoperative biliary ischemic stenosis and biliary fistula. A 3D model of extrahepatic bile duct blood supply in a patient undergoing duodenum-preserving pancreatectomy showed that the lower part of the common bile duct was mainly supplied by the gastroduodenal artery and the pancreaticoduodenal anterior artery. The anterior pancreaticoduodenal artery arch was formed to supply duodenal blood, and the lower extrahepatic bile duct blood supply was digitally classified as type II. According to the 3D model, the anterior pancreaticoduodenal artery arch was successfully preserved during the operation without biliary fistula or duodenal fistula. No stricture of bile duct occurred after a 1-year follow-up.

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Fig. 9.28  Blood supply of the lower extrahepatic bile duct (Type IC). (a) The posterior superior pancreaticoduodenal artery and the posterior portal artery supply the lower extrahepatic bile duct; (b) The posterior

Fig. 9.29  The gastroduodenal artery and its branches (the anterior pancreaticoduodenal artery) supply the lower extrahepatic bile duct and form the anterior pancreaticoduodenal arch

9.4.3.2 Significance of 3D Visualization of Extrahepatic Bile Duct Blood Supply in Surgical Decision Making of Extrahepatic Bile Duct Obstructive Diseases In patients with extrahepatic bile duct obstructive disease, the bile duct is dilated, and the blood supply to the bile duct is bound to increase. The artery supplying blood to the bile

superior pancreaticoduodenal artery and the posterior portal artery supply the lower extrahepatic bile duct

duct will increase in diameter and increase the branch compensation mechanism to meet the increase in bile duct blood supply. Moreover, the main blood supply to extrahepatic bile ducts, that is, the right hepatic artery and gallbladder artery, vary considerably. If the source and distribution of extrahepatic bile duct blood supply cannot be recognized before the operation, it may be damaged during operation, which may lead to complications such as biliary bleeding, postoperative biliary fistula, stricture of extrahepatic bile duct, or cholangio–intestinal anastomosis. The 3D model of extrahepatic bile duct blood supply based on submillimeter CT data can provide three-­ dimensional visual distribution characteristics of individual extrahepatic bile duct blood supply and become a “digital fluoroscopic eye” helping biliary surgeons to understand the internal structure of living human body. A 3D model of extrahepatic bile duct blood supply clearly showed that the variant right hepatic artery originated from the superior mesenteric artery and passed through part of the pancreatic tissue during the course of the operation. In pancreaticoduodenectomy, the injury of the right hepatic artery was avoided, and the right hepatic artery was dissected thoroughly, thus preserving the arterial blood supply of the right half liver and the upper extrahepatic bile duct (Fig. 9.33). Biliary fistula and bile duct stenosis after extrahepatic cholangiostomy are strongly related to injury to the anterior wall of the bile duct during the operation. The 3D model of extrahepatic bile duct blood supply can be used to understand the distribution of arteries attached to the anterior wall of the extrahepatic bile duct before operation and thus guide the location of the longitudinal incision of the extrahepatic

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

a

b

Fig. 9.30  Blood supply of the lower extrahepatic bile duct (Type III). (a) The cystic artery arising from the gastroduodenal artery supplies the lower segment of the extrahepatic bile duct; (b) The cystic artery arising

Table 9.3  Digital classification of blood supply of the lower extrahepatic bile duct in 41 patients with biliary obstruction (Yang 2017)

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from the gastroduodenal artery supplies the lower segment of the extrahepatic bile duct

Types Type IA Type IB Type IC Type II Type III

N 13 13 4 7 0.4

Incidence (%) 31.7 31.7 9.8 17.0 9.8

b

Fig. 9.31  Intraoperative picture of blood supply to extrahepatic bile duct. (a) The superficial vascular network and bile duct of the 9 o’clock artery (blue arrow); (b) 3 o’clock artery (indicated by vascular forceps)

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Fig. 9.32  Postoperative cholangiography and MRCP results: typical case 3, The MRCP examination 1 year after the operation showed no extrahepatic bile duct stricture

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Fig. 9.34  The 3D model suggests that the right hepatic artery and the proper hepatic artery send out large branches on the anterior wall of the extrahepatic bile duct to supply the bile duct

making of cholangioenterostomy and the location of the biliary anastomosis. Typical case 1 (Resource 9.1: case 1): The patient was diagnosed with inflammatory stenosis of the lower common bile duct. Conservative treatment and endoscopic duodenal papilla incision were ineffective, and bile drainage was needed through choledochojejunostomy. The preoperative 3D model of the extrahepatic bile duct supply suggested that the common hepatic bile duct blood supply was composed of “9 o’clock” artery and right hepatic artery formed by the main gallbladder artery. The lower part of the common bile duct blood supply was supplied by the superior and posterior pancreaticoduodenal artery, but no obvious arterial blood supply was found in the upper part of the common bile duct and duodenum. Above all, the extrahepatic bile duct was cut off at the level of the common bile duct with abundant blood supply, and Fig. 9.33 Variation of hepatic artery passing through pancreatic end-to-side cholangiojejunostomy was performed. Typical parenchyma case two (Resource 9.1: case 2) was also diagnosed with inflammatory stenosis in the lower common bile duct, but bile duct. A patient with lower choledocholithiasis was the individual 3D model suggested that the extrahepatic scanned and a 3D model constructed (Fig. 9.34). The model bile duct blood supply of the patient was variable, and the showed the right hepatic artery and the proper hepatic artery cholecystic artery originated from the gastroduodenal supplying the anterior wall of the extrahepatic bile duct artery. The intestinal artery, which is close to the right-side (Fig. 9.34). The location of the incision was selected accord- wall of the extrahepatic bile duct, enters the gallbladder ing to the model so as to avoid complications such as biliary and forms a “9 o’clock” artery for ascending blood supply. fistula or late biliary stricture, injury to the anterior wall of If the patient receives an extrahepatic bile duct transection the blood supply artery was avoided when the extrahepatic and end-to-side cholangiojejunostomy, the arterial blood bile duct was cut open, sutured, and closed. supply may be destroyed at 9 o’clock. Therefore, side-­to-­ The three-dimensional visualization model of extrahe- side cholangiojejunostomy was selected as the operative patic bile duct blood supply can assist in the decision-­ method.

9  Application of 3D Visualization for Blood Supply of Extrahepatic Bile Ducts

The extrahepatic bile duct blood supply artery is accompanied by the biliary tract along its course, and inflammatory ulceration of the bile duct may be caused by the incarceration of the extrahepatic bile duct stone. If the distribution of the blood supply of the extrahepatic bile duct and the adjacent relationship between the stone and the blood supply of the extrahepatic bile duct are not fully understood before the lithotomy, misguided lithotomy can cause extrahepatic bile duct hemorrhage. It is impossible to deal with the anatomic characteristics of individual bile duct blood supply accurately and properly when extrahepatic bile duct hemorrhage occurs. In cases of massive hemorrhage of the posterior wall of the common bile duct, the ligation of the proper hepatic artery and the gastroduodenal artery is not effective. The blood vessels of the posterior wall of the bile duct were sutured in a wide range of upper and lower areas before the bleeding was stopped. These facts suggest that blood flow from the posterior portal vein plays a vital role in the blood supply of the bile duct. The 3D model of the extrahepatic bile duct in one patient clearly showed that the pos-

Fig. 9.35  The 3D model suggests that the posterior portal artery supplies extrahepatic bile duct blood close to the posterior wall of the common bile duct, and abundant arteries can be seen interlacing into a network in the bile duct wall behind incarcerated stones (posterior view)

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terior portal vein artery originated from the superior mesenteric artery converged with the posterior pancreaticoduodenal artery at the posterior end of the bile duct and continued to supply blood to the bile duct along the posterior wall of the extrahepatic bile duct, and the posterior wall of the bile duct at the lower end of the common bile duct incarcerated with stones forms a rich supply arterial network (Fig. 9.35) (Yang 2017). Guided by the 3D model, the stone was removed gently under the direct view with a choledochoscope during the operation, and the procedure of stone extraction was smooth. Even if biliary bleeding occurs ­during lithotomy, the bleeding artery can be accurately determined based on a three-dimensional visual model of extrahepatic bile duct blood supply without blindly and experimentally ligating the peripheral artery, avoiding greater body damage or complications. Typical cases of extrahepatic biliary tract obstruction with 3D visualization are attached.

References Ayoub WS, Esquivel CO, Martin P.  Biliary complications following liver transplantation. Dig Dis Sci. 2010;55(6):1540–6. https://doi. org/10.1007/s10620-­010-­1217-­2. Balderramo D, Navasa M, Cardenas A. Current management of biliary complications after liver transplantation: emphasis on endoscopic therapy. Gastroenterol Hepatol. 2011;34(2):107–15. https://doi. org/10.1016/j.gastrohep.2010.05.008. Cameron GR, Hou CT. An experimental study of stricture of the common bile-duct in the guinea-pig.[J]. Journal of Pathology & Bacteriology, 1962, 83:265. Fang C. Digital hepatic surgery[M]. Beijing: People’s Military Medical Press; 2014. p. 139–62. Northover JM, Williams ED, Terblanche J. The investigation of small vessel anatomy by scanning electron microscopy of resin casts. A description of the technique and examples of its use in the study of the microvasculature of the peritoneum and bile duct wall. J Anat. 1980;130:43–54. Park KM, Lee SG, Lee YJ, et al. Adult-to-adult living donor liver transplantation at Asian Medical Center, Seoul, Korea. Transplant Proc. 1999;31(1–2):456–8. Shapiro AL, Robillard GL. The arterial blood supply of the common and hepatic bile ducts with reference to problems of common duct injury and repair: based on a series of 23 dissections. Surgery. 1948;23:1–4. Terblanche J, Allison  HF, Northover JMA. An ischemic basis for biliary strictures. Surgery. 1983;94:56. Yang J, Tao H, Fang C, et al. Clinical Applications of ThreeDimensional Visualization Model of Arteries Supplying the Extrahepatic Bile Duct for Patients with Biliary Obstruction[J]. Am Surg. 2017.

Digital Surgical Diagnosis and Management of Cholecystolithiasis

10

Nan Xiang, Songsheng He, and Chihua Fang

10.1 Introduction The majority of cholecystolithiasis presents predominantly with cholesterol stones, whereas the remainder consists of mixed cholesterol and black pigment stones. Females have a higher prevalence of cholecystolithiasis than males, and the frequency of this disease increases with age, escalating significantly in their 40s. The causes of cholecystolithiasis are very complicated and are associated with various factors. Risk factors that affect the change in the ratio of cholesterol to bile acid concentration and cause cholestasis, can lead to stone formation, such as race, gender, obesity, pregnancy, high-fat diet, long-­term parenteral nutrition, diabetes, hyperlipidemia, and cirrhosis. In China, the incidence of cholecystolithiasis in the northwest is high, which may be related to dietary habits. Most patients are asymptomatic, with stones only discovered accidentally during physical examination, surgery and autopsy, and become stationary gallstones. With the popularization of health examination, the discovery of asymptomatic gallstones has increased significantly. Only a few patients present with biliary colic symptoms typical of cholecystolithiasis. The majority manifest as acute or chronic cholecystitis. Jaundice rarely occurs. Small stones can enter through the cystic duct and stay in the common bile duct to become common bile duct stones, which can induce biliary pancreatitis. Chronic perforation of cholecystitis caused by stone compression can result in Mirizzi syndrome, cholecystoduodenal fistula, or cholecystocolonic fistula. Long-term stimulation by stones, and inflammation, can induce gallbladder cancer. B-mode ultrasound is the first-line imaging modality in evaluating cholecystolithiasis, with a reported sensitivity of approximately 100% (Hwang et  al. 2014); approximately 10–20% of gallstone contain enough calcium to be visible by

N. Xiang · S. He · C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China

abdominal X-ray (Zeman 1994; Bortoff et al. 2000; Chuah et al. 2017); CT and MRI can also display gallstones, but not as a routine examination. With the development of digital medicine, 3D visualization has been widely used in preoperative evaluation of hepatobiliary and pancreatic diseases as well as in the intraoperative navigation of surgery. Laparoscopic cholecystectomy is preferred for gallstones with symptoms and/or complications. Preoperatively, 3D visualization can be used to evaluate cholecystolithiasis more accurately, to guide surgeons to perform more precise operations, and to reduce the incidence of surgical complications (Fan et  al. 2013; Zeng et al. 2016).

10.2 Application of 3D Visualization in Cholecystolithiasis Currently, for most patients with cholecystolithiasis with simple conditions and no anatomic variation, the diagnosis can be confirmed by preoperative B-ultrasound. However, for some complicated diseases, such as repeated acute calculous cholecystitis, severe adhesion in the triangle area, unclear or variable anatomical relationship, patients with portal hypertension, complex vasculature in the portal area; surgeons need to perform cholecystectomy according to the specific conditions encountered during the operation. It is impossible to know in advance all the patient’s individual anatomical characteristics (such as variations of gallbladder and right hepatic arteries), and the lack of foresight for potential risks of surgery, especially for beginners, may result in iatrogenic injury during operation. In recent years, with the rapid development of digital medicine, 3D visualization has been widely applied clinically. Through preoperative 3D modeling by MI-3DVS software, the anatomical structure of abdominal parenchymal organs and celiac vessels, as well as their spatial relationships, can be accurately displayed stereoscopically; this helps surgeons to understand (a) the shape of the gallbladder,

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(b) the distribution, shape, and size of the gallstones, and (c) the spatial relationship between the gallbladder and the surrounding organs, blood vessels and tissue preoperatively. Moreover, 3D reconstructed models can help foresee situations that may arise during the operation due to anatomic variations. In order to improve the safety of the operation and promote the recovery of patients after surgery, surgical preoperative planning can be trialed with the aid of a surgical simulation system. Surgical plans can be rehearsed repeatedly and the optimal individualized surgical procedures can be selected, thereby improving the safety of operation and promoting postoperative recovery.

subsequently transmitted to the terminal server for 3D imaging through the internal network and exported to obtain the available thin-layer original CT image data (Fig. 10.1).

10.2.1 3D Visualization Workflow

10.2.1.3 3D Reconstruction

10.2.1.1 Acquisition of Thin-Slice CT Data Multiphase images (plain scan, arterial, hepatic venous, and portal venous phase) should be obtained first, and then these images [with a slice thickness of 5 mm] should be imported into a Mxview workstation and sliced into 0.625  mm, using the digital imaging and communications in medicine (DICOM) 3.0. format. These processed images should be

3D Reconstruction of Blood Vessels • 3D Reconstruction of Arteries Conventional enhanced CT data in the arterial phase was segmented and reconstructed by surface rendering (Fig. 10.4a); CTA data were reconstructed by volume rendering, with the advantage of high speed and high quality. During the reconstruction process, it may not be possible to reconstruct some arte-

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10.2.1.2 Image Segmentation CT image was imported into MI-3DVS for automated image segmentation (Fig. 10.2). MI-3DVS was used to segment the CT data of each phase quickly and the results were satisfactory. Data were obtained from the gallbladder, gallstone, liver, portal vein, and hepatic artery. A few unsatisfactory segmentation can be corrected by adjusting the threshold value for further 3D reconstruction (Fig. 10.3).

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rial terminal branches while adjusting the threshold value, because of the need to complete operations such as bone removal. In this case, local vascular surface rendering can be used to supplement the modelling, and then the effect of 3D reconstruction of the arterial system can be fully displayed in a combined form. • 3D Reconstruction of the Portal Venous System CT data of the portal venous system was segmented and Fig. 10.2  Automatic image segmentation. (a) Read pictures in a DICOM viewer; (b) data are converted and saved; (c) import data in MI-3DVS to prepare for segmentation; (d) 3D reconstruction is performed in the MI-3DVS; (e) liver segmentation; (f) Gallbladder segmentation; (g) calculus segmentation; (h) arterial system segmentation; (i) portal venous system segmentation; (j) hepatic venous system segmentation

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reconstructed by surface rendering (region growing method) (Fig. 10.4fb). 3D Reconstruction of the Gallbladder, Gallbladder Stones, and Biliary Tract • Data for gallbladder and biliary reconstruction in the arterial or venous phase, requires reasonable selection based on the gallbladder, biliary tract, and surrounding tissues.

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Fig. 10.3  Image segmentation. (a) Gallbladder segmentation; (b) calculus segmentation; (c) liver and gallstone segmentation

Enhanced scan data with substantial differences in CT thresholds between gallbladder, biliary tract, and surrounding tissues were selected as sources of 3D reconstruction data (Fig. 10.4c). • Stones were segmented and reconstructed by surface rendering. • The specific reconstruction method is the same as that of the liver (Fig. 10.4d). • Segmentation and reconstruction of gallbladder image with an unclear boundary require several steps to reconstruct organs. Finally, the reconstruction of the gallbladder is completed by the combined function (Fig. 10.4e–h).

10.2.1.4 Surgical Simulation The 3D models of liver and gallbladder were imported into the FreeForm Modeling System for smoothing and removing some excessive details and noises. They could be com-

bined and displayed stereoscopically to be observed from all directions, and they could also be enlarged, reduced, and rotated. Different tissue structures were rendered in different colors: the liver was reddish-brown, the bile duct was green, the bile duct stone was black, the artery was red, the portal vein was purple, and the hepatic vein was blue; which increased the stereoscopic sensation of the 3D hepatobiliary model. The simulated cholecystolithiasis was performed using PHANTOM, force feedback equipment. Surgical Procedure Step 1 When the transparency of liver and gallbladder is set at 0.5 (50%), the distributions of blood vessels and gallstones in the liver are visible (Fig. 10.5). Step 2 Activate the arterial system, introduce a needle to suture the cystic artery (Fig. 10.6), and cut the gallbladder artery (Figs. 10.7 and 10.8).

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ency of the liver is 0, showing its internal structure; (g) Biliary tract transparency is set to 0 to show calculi; (h) The transparency of liver and biliary tract is 0, showing the location of calculi

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Step 3 Activate the gallbladder, introduce a scalpel, and show the process of incision of the gallbladder bed (Figs. 10.9 and 10.10). Step 4 Show the resection line of the gallbladder (Fig. 10.11), and remove the gallbladder (Fig. 10.12). Step 5 Introduce the needle, suture the end of the cystic duct (Fig. 10.13), and show the suture of the cystic duct (Fig. 10.14).

10.2.2 Application Value of 3D Visualization in Gallbladder Stone Difficulties that cannot be foreseen by traditional imaging before an operation may frequently be encountered during cholecystectomy. For example:

• Variation in the origin, course, and number of gallbladder arteries, which may increase the risk of intraoperative gallbladder artery hemorrhage. • A variant right hepatic artery issuing from the superior mesenteric artery courses through the posterior or right posterior of extrahepatic bile duct, and then enters into the liver through the posterior triangle of the gallbladder, which may increase the risk of injury of the right hepatic artery during the operation. • Variation of the gallbladder duct and extrahepatic bile duct may increase the risk of bile duct injury. • The exposure of the branches of middle hepatic vein or portal vein to the gallbladder bed may increase the risk of accidental hemorrhage during operation. • Recurrent acute attack of cholecystitis may result in fusing with surrounding organs and tissues and unclear anatomical detail.

10  Digital Surgical Diagnosis and Management of Cholecystolithiasis Fig. 10.5  The structure of gallbladder stones and blood vessels is visible when the transparency of liver and gallbladder is set at 0.5

Fig. 10.6  Simulation of gallbladder resection, and suture of the gallbladder artery

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Fig. 10.8  Cut off the cystic artery

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10  Digital Surgical Diagnosis and Management of Cholecystolithiasis Fig. 10.9  Gallbladder bed cut open

Fig. 10.10  Procedure of gallbladder bed incision

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10  Digital Surgical Diagnosis and Management of Cholecystolithiasis Fig. 10.13  Suture the cystic duct

Fig. 10.14  Suture line of the cystic duct

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• In complicated portal hypertension, the hepatic portal area is complicated by blood vessels and there are many pathological variations of vessels. The thin varicose vein wall is easily damaged, causing bleeding. All of these above factors may increase iatrogenic injury and even lead to life-threatening intraoperative bleeding that is difficult to control. For the above-mentioned laparoscopic cholecystectomy, 3D visualization technology has a unique guiding advantage over traditional imaging technology. Through preoperative study of 3D visualization on patients with cholecystolithiasis: • The shape of the gallbladder, the shape and distribution of gallstones, and the anatomical relationship between the gallbladder and its surrounding organs are stereoscopically displayed. • The anatomical relationship of the anterior and posterior triangle of the gallbladder are clearly displayed and the flow of the blood vessels is observed. • The variation of the bile duct, gallbladder neck duct, gallbladder artery, and the right hepatic artery was evaluated. • In patients with choledocholithiasis and Mirizzi syndrome, the course of the extrahepatic bile duct, and its dilatation or stenosis is demonstrated in three dimensions. • The gallbladder bed with or without the variability of the hepatic vein branch or portal vein exposure is individually displayed in order to prevent accidental bleeding during the operation. On this basis, we can also use the construction of three-­ dimensional visualization platforms for virtual surgery, and change the traditional methods of diagnosis and treatment, so that clinicians can obtain more intuitive and realistic clinical data so as to formulate detailed and rational

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treatment plans for patients and optimize the operation method. It also provides the doctors with opportunities for rehearsal repeatedly before the operation, to increase their proficiency and cooperation, thus speeding up the progress of the operation, increasing the probability of success, and reducing complications. The visualization of surgery can also change the traditional medical teaching model; that is, it no longer relies on the traditional method of learning surgery solely by carbon pen, hand-drawn line, and anatomical atlas. Instead, it relies on three-dimensional images from real patients as the object of operation research. It provides a real and intuitive operation process for classroom teaching, as well as for the operation teaching of graduate students, intern doctors, and advanced students; increasing the opportunity to practice, improving learning efficiency, and shortening the learning curve.

References Bortoff GA, Chen MY, Ott DJ, Wolfman NT, Routh WD. Gallbladder stones: imaging and intervention. Radiographics. 2000;20(3): 751–66. Chuah PS, Curtis J, Misra N, Hikmat D, Chawla S. Pictorial review: the pearls and pitfalls of the radiological manifestations of gallstone ileus. Abdom Radiol (NY). 2017;42(4):1169–75. https://doi. org/10.1007/s00261-­016-­0996-­0. Fan Y, Xiang N, Wang L.  Three-dimensional laparoscopic cholecystectomy: a case report and literature review. J South Med Univ. 2013;33(12):1856–7. Hwang H, Marsh I, Doyle J.  Does ultrasonography accurately diagnose acute cholecystitis? Improving diagnostic accuracy based on a review at a regional hospital. Can J Surg. 2014;57(3):162–8. Zeman RK.  Cholelithiasis and cholecystitis. In: Gore RM, Levine MS, Laufer I, editors. Textbook of gastrointestinal radiology. Philadelphia, PA: Saunders; 1994. p. 1636–74. Zeng N, Fang C, Yang J, et al. Application of three-dimensional laparoscopic cholecystectomy for complicated gallstone disease. J South Med Univ. 2016 Jan;36(1):145–7.

Digital Surgical Diagnosis and Management of Extrahepatic Cholelithiasis

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Yunqiang Tang, Xu Chang, and Chihua Fang

11.1 Introduction Extrahepatic cholelithiasis is a frequently occurring biliary tract disease in China. It commonly manifests by obstruction of the common bile duct and leads to acute cholangitis; if not treated in a timely manner, it will cause acute obstructive suppurative cholangitis or acute severe cholangitis, eventually progressing into shock and loss of consciousness. The condition is dangerous, with a high mortality rate. Surgical intervention remains the primary therapy and the only effective treatment for extrahepatic cholelithiasis; however, reoperation on the extrahepatic bile duct is one of the most frequent reoperations in abdominal surgery. Reoperation following biliary tract surgery is more complicated than the initial procedure, and the scope of surgery is wider. It not only increases the suffering and financial burden of patients but also easily leads to medical disputes. The leading causes of reoperation include residual and/or recurrence of bile duct stones, as well as bile duct injury and stenosis of various etiologies. In addition to the influence of many factors, such as the condition of the disease, the level of technology, the condition of the equipment, insufficient preoperative understanding of the anatomical abnormalities such as the site, and quantity of biliary tract stones; the extent of stenosis and dilatation, as well as the distribution of blood vessels, are also relevant. In recent years, there have been considerable efforts made toward promoting the development of digital surgical treatment and management of extrahepatic cholelithiasis. Peng Weibin et al. (2005) used MSCT virtual endoscopy to detect Y. Tang Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China X. Chang Panyu District Hospital of Traditional Chinese Medicine, Guangzhou, China C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China

biliary calculus, and they believed that endoscopy could accurately display the 3D dynamics of the stones; the size and location of stones observed at any angle in 3D space were consistent with the findings of ultrasound, transverse axis CT or surgery. Fasel et al. (1996, 2010) and Fasel and Schenk (2013) reconstructed the main branches of the liver, gallbladder, intrahepatic vein system, and intrahepatic and extrahepatic biliary system using the VHP dataset. The model was used to simulate the minimally invasive and endoscopic procedures for the surgical treatment of biliary diseases. Other scholars have carried out researches on 3D reconstruction of hepatobiliary system images. For example, Giadás et al. (2002) evaluated the role of helical computer tomographic cholangiography (HCT-C) in the visualization of the biliary tract. Using data of intrahepatic and extrahepatic cholelithiasis obtained by 64-slice spiral CT scan, Fang et al. carried out a research on 3D visualization and surgery simulation, by which surgical planning could be optimized and preoperative rehearsal be performed, thereby improving surgical safety and reduce complications (Fan et al. 2007). Digital surgery has been developing at an amazing rate and increasingly being been used to guide the diagnosis and management of extrahepatic cholelithiasis.

11.2 3  D Modelling of Extrahepatic Cholelithiasis Extrahepatic cholelithiasis refers to stones located in the common bile duct, common hepatic duct, left hepatic duct, and right hepatic duct, of which choledocholithiasis accounts for the majority. B-ultrasound can detect the intrahepatic bile duct dilatation and intracavitary stones with good sensitivity. At the same time, it can show the pathological changes in the liver parenchyma and is the first choice for the examination of hepatolithiasis. However, B-ultrasound cannot show the complete picture of the biliary system, especially the stricture of the bile duct, the results are easily affected by the subjective experience of the examiner, and there has a

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r­ecognized rate of misdiagnosis. Therefore, the results of B-ultrasound cannot solely be used as the basis for surgery. CT can show the distribution of hepatolithiasis, the systemic images of the bile duct and hepatic parenchyma lesions, and has a significant value in the diagnosis of hepatolithiasis. Stereoscopic conformation of the intrahepatic bile duct system and the distribution of intrahepatic stones can be obtained by observing the CT photographs of each level systematically. MRCP is a noninvasive method for the diagnosis of the biliary tract. It can display an intrahepatic bile duct tree in various directions. Combined with the original image, it can accurately judge the distribution of intrahepatic stones, lesions of the bile duct system, and hepatic parenchyma. It is superior to CT and direct biliary tract imaging in the diagnosis of hepatolithiasis. PTC and ERCP can clearly show the whole picture of the bile duct system and provide an essential basis for surgical treatment. However, PTC and ERCP cannot show lesions outside the bile duct. Moreover, both, as invasive examination methods, may cause some severe complications. Thus, their indications should be strictly controlled. With the development of digital surgery for extrahepatic cholelithiasis, a three-dimensional biliary tract model can be established by using a 64-row spiral CT with high temporal and spatial resolution and using advanced equipment with powerful data processing ability. It is more favorable for preoperative evaluation and optimization of surgical options.

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11.2.1 Image Data of Choledocholithiasis Scanned by 64-Slice Spiral CT The methods are the same as those mentioned above. Traditional two-dimensional CT images (Fig. 11.1) are converted to BMP format by DICOM viewer software with 415 × 303 × 32b specification and an 832 MB data set size (Fig.  11.2). The contour of the liver is precise, the cross-­ section tube contrast agent is well filled, the various vascular tubes are clear, and the stones are located about 1.5 cm × 1.5 cm in the lower part of the common bile duct (Figs. 11.1b and 11.2d).

11.2.2 Image Registration The specific method is the same as the above described (Fig. 11.2a, b).

11.2.3 Image Segmentation and 3D Modelling The BMP data containing choledocholithiasis were imported into the medical image processing system to complete automatic image segmentation and 3D reconstruction (Fig. 11.3). The model was further processed by introducing the FreeForm Modeling System. After smoothing, and removing

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Fig. 11.2  DICOM view and its image converted to BMP format. (a) ICOM viewer reads CT images; (b) Convert to BMP format in DICOM viewer and save; (c) BMP image of choledochal dilatation; (d) BMP image of calculi in the lower segment of common bile duct

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the layering and noise, a three-dimensional model with realistic configuration and strong stereoscopic effect can be obtained. The abdominal aorta and its branches are clearly displayed in the arterial system, and the hepatic artery and the left hepatic artery, the right hepatic artery, and its subordinate branches are also clearly displayed (Fig. 11.4a). The right branch of the hepatic vein and the main trunk of the middle hepatic vein show well in the venous system, and the branches of the hepatic vein can also be clearly displayed under normal conditions. Because there are left intrahepatic bile duct stones with extrahepatic bile duct stones and left liver atrophy, the model can only identify the third-grade hepatic vein of the right liver with the naked eye, and not the left hepatic vein, which is consistent with the atrophy of the left liver seen in the original image (Fig. 11.4c). The portal vein was well displayed, almost reaching the five branches of the portal vein and the splenic vein (Fig. 11.4b), and the hepatobiliary system model was consistent with the original structure, and when the transparency of the biliary tract was 0.25, the stones could be seen (Fig. 11.4d, e).

11.3 V  irtual Surgery for Extrahepatic Cholelithiasis As mentioned above, a 64-slice spiral CT can be utilized to perform visualization research of the biliary tract system and to establish a three-dimension bile duct model. Simultaneously, visual simulation surgery can be carried out, which makes the preoperative evaluation and selection of a surgical plan more reasonable.

11.3.1 Secondary Development and Visual Simulation of Virtual Surgical Instruments The SLT format of choledocholithiasis and the models of liver, bile, pancreas, and spleen were introduced into the FreeForm Modeling System to be processed to smooth and remove the layer and noise. However, because the system does not have the virtual surgical instruments, the secondary development of the surgical instruments is carried out using the GHOST SDK software, and the molds of the secondarily developed instruments and devices, such as T-shaped tubes, are imported into the system to perform visual simulation of choledocholithotomy and T-tube drainage. The specific steps are as follows: • Step 1 When the transparency of the liver is 1, the three-­ dimensional model of the liver and gallbladder is displayed (Fig. 11.5). When the transparency of the liver is 0.5, the internal structure of the liver is shown (Fig. 11.6). When the transparency of the liver and gallbladder is 0.5, the stones at the lower end of the common bile duct are shown (Fig. 11.7). When the transparency of the liver and bile duct is 1 and 0.5, respectively, the black stones at the lower end of the common bile duct are visible (Fig. 11.8). • Step 2 Activate the biliary system, introduce a virtual scalpel, and cut the lower end of the common bile duct (Fig. 11.9). • Step 3 Introduce lithotripsy forceps to perform the process of removing the stones at the lower end of the common bile duct (Fig. 11.10a, b, c).

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Fig. 11.3  Image segmentation and 3D reconstruction. (a) Import BMP data in MIPS for segmentation; (b) 3D reconstruction in MIPS; (c) segmentation of the liver; (d) segmentation of gallbladder and common

bile duct; (e) segmentation of common bile duct stones; (f) segmentation of the arterial system; (g) segmentation of hepatic veins; (h) segmentation of portal vein

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Fig. 11.4  3D reconstruction effect. (a) Reconstructed arterial system; (b) Reconstructed portal vein system; (c) Reconstructed hepatic veins; (d) Reconstructed biliary tract system; (e) Calculi were visible when the transparency of reconstructed hepatobiliary and bile ducts was 0.25

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Fig. 11.5 Reconstructed hepatobiliary, pancreatic, and spleen model

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11  Digital Surgical Diagnosis and Management of Extrahepatic Cholelithiasis Fig. 11.6  The transparency of the liver is 0.5, showing the tubular structure inside the liver

Fig. 11.7  Calculi are revealed when hepatobiliary transparency is 0.5

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Fig. 11.9  Activation of biliary tract system, introduction of virtual scalpel, and cutting the common bile duct

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Fig. 11.10  3D visualized simulation surgery—simulation of stone removal process. (a) Introduce the lithotomy forceps to carry out the stone removal; (b) stone removal process; (c) remove the stone

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• Step 4 Introduce the T-tube and insert the needle into the lower end of the common bile duct (Fig. 11.11a, b, c). • Step 5 Introduce the needle, suture, and knot and perform the suturing process of the common bile duct incision and T-tube indwelling (Fig. 11.12a, b, c).

11.3.2 Significance of 3D Visualization in the Management of Choledocholithiasis

With the continuous progress of imaging techniques such as MSCT and MRI, people’s understanding of internal structure The STL format of the liver, bile, pancreas, and spleen changes of the hepatobiliary system caused by hepatobiliary model of choledocholithiasis was imported into the FreeForm diseases has deepened. In recent years, the development of Modeling System. The model can be magnified, reduced, computer technology and image processing technology has and rotated in all directions. It can be seen that the internal promoted research on the visualization of liver and gallbladstructure of the model is faithful to the original two-­ der. However, there is still a long way to go with clinic dimensional image. Different systems were rendered in dif- requirements. At present, there are many studies on the ferent colors: the liver was reddish-brown, the bile duct was whole digitized virtual human dataset at home and abroad as green, the bile duct stone was black, the artery was red, the well as the use of perfused liver specimens to study the strucportal vein was purple, the hepatic vein was blue, the pan- ture of liver internal pipeline or to use medical imaging creas was yellow, and the spleen was purplish-red. The 3D equipment such as CT, MRI, 3DCT, and workstations model is more stereoscopic and realistic. The internal duct brought in by the instruments to reconstruct the viscera, but structure and the location of stones can be displayed by set- there are some shortcomings. The 64-slice spiral CT scanting different transparency (Figs. 11.5, 11.6, 11.7, and 11.8). ning data of intrahepatic and extrahepatic bile duct stones The secondary virtual surgical instrument T-tube is similar to provides clear submillimeter data, which can be used for 3D the real one. The manipulation force feedback device visualization stereo imaging assisted by a computer. (PHANTOM) can be used to perform visual simulation surComputer-aided surgery (CAS) is a new technology gery for choledocholithotomy and T-tube drainage based on the high-speed processing and controlling of (Figs. 11.9, 11.10, 11.11, and 11.12). data. It can provide ­technical support for surgeons through

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Fig. 11.11  3D visualized simulation surgery—simulating the indwelling of T tube. (a) Introduce t-tube; (b) indwell the T-tube; (c) bile duct transparency is 0.5, showing the position of the T-tube

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a virtual environment to make the operation safer and more accurate. In recent years, with the development of diagnostic imaging instruments such as CT and MRI, the application of computer virtual reality technology in medicine has rapidly developed. Virtual surgery is an emerging discipline that uses a variety of medical image data to create a simulated environment in a computer using virtual reality technology. Doctors use the information from the virtual environment for surgical planning, training, and guiding the surgeon during the actual operation process. After the establishment of a virtual surgical system for biliary calculi, the automatic image segmentation and 3D reconstruction were carried out through the MIPS system (using the CT image information obtained preoperatively on the patients with cholelithiasis); enabling rapid building of the 3D model. In the virtual environment established

by the computer, the operation process, position, and angle of the incision were well-designed, thus improving the success rate of the operation. Moreover, surgical training is crucial because 80% of the errors in surgical teaching and training are caused by human factors. Young doctors can observe the expert’s surgical procedure on the system and repeat the exercise. Virtual surgery has greatly shortened the time required for surgical training while reducing the need for expensive subjects. Since the virtual surgery system can provide the operator with a realistic and immersive training environment, Force feedback rendering algorithms can create a good sense of presence, so the training process is almost identical to the real situation, especially the hand feeling of the actual operation. This technique has opened up a new model of medical teaching that helps solve the difficulties of clinical medical training and education.

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Fig. 11.12  3D visualized simulation surgery—simulating the process of suture of bile duct and indwelling of T-tube. (a) Introduce the suture needle to suture the common bile duct; (b) suture the common bile duct; (c) suture of the common bile duct incision

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References Fan Y, Fang C, Zhu X. Clinical application of three-dimensional imaging of 64-slices spiral CT cholangiography in pathological diagnosis of hepatolithiasis. Chin J Dig Surg. 2007;6(6):428–32. Fasel JH, Schenk A. Concepts for liver segment classification: neither old ones nor new ones, but a comprehensive one. J Clin Imaging Sci. 2013;3:48. https://doi.org/10.4103/2156-­7514.120803. Fasel JHD, Muster M, Gailloud P, Mentha G, Terrier F.  Duplicated hepatic artery: radiologic and surgical implications. Acta Anat. 1996;157:164–8.

Fasel JH, Majno PE, Peitgen HO. Liver segments: an anatomical rationale for explaining inconsistencies with Couinaud’s eight-segment concept. Surg Radiol Anat. 2010;32:761–5. Giadás T, Octavio de Toledo L, Asensio M, et al. Helical CT cholangiography in the evaluation of the biliary tract: application to the diagnosis of choledocholithiasis. Abdom Imaging. 2002;27:61–70. Peng W, Chen G, Zhao L, et al. MSCT virtual endoscopy: primary clinical applications in the detection of biliary calculus. J Jiangsu Univ (Medical Edition). 2005;015(002):124–5.

Digital Surgical Diagnosis and Management of Hepatolithiasis

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Qiping Lu, Jian Yang, Ping Wang, Jun Liu, Yingfang Fan, and Chihua Fang

12.1 Introduction Hepatolithiasis refers to stones that originated from the intrahepatic biliary system, which can exist alone or coexist with extrahepatic bile duct stones. As a common biliary tract disease that is difficult to treat, hepatolithiasis is characterized by slow progress and severe consequence. When the hepatobiliary system suffers from progressive damage caused by diffuse stone obstruction and recurrent cholangitis, it can lead to severe complications such as biliary cirrhosis and portal hypertension, cholangiocarcinoma, liver failure, and eventually to the final stage of biliary disease. It has become the most challenging problem in hepatobiliary surgery and liver transplantation and is an important cause of death in benign biliary tract diseases in China. Since the 1950s, Professor Zhiqiang Huang has organized domestic specialists to perform researches on the diagnosis and management of hepatolithiasis from various perspectives. Based on the clinical and pathological studies of a large number of cases, it is recognized that intrahepatic cholangiolithiasis is a strict intrahepatic segmental lesion. In the pathological range, the liver tissue has the corresponding pathology such as fibrosis, atrophy, and loss of function Electronic Supplementary Material The online version of this chapter (https://doi.org/10.1007/978-­981-­33-­6769-­2_12) contains supplementary material, which is available to authorized users. Q. Lu General Hospital of Central Theater Command, Wuhan, China J. Yang · Y. Fan · C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China P. Wang First Affiliated Hospital, Guangzhou Medical University, Guangzhou, China J. Liu Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China

(Huang 2014). In 1957, regular hepatectomy to treat hepatolithiasis was initiated by prof. Zhiqiang Huang; later on, the principle of “relieving the obstruction, removing lesions and building unobstructed drainage” was described (1959). This principle has laid the foundation for the surgical treatment of hepatolithiasis. In 1983, The Biliary Surgery Branch of the Chinese Medical Association established the definition, nomenclature, and diagnostic criteria for hepatolithiasis; and the diagnostic criteria for acute obstructive suppurative cholangitis and standards for marking stone sites were formulated. In the 1980s and 1990s, at the time when information technology was still relatively backward, two clinical epidemiological investigations of cholelithiasis were organized. According to 357 cases of hepatectomy and postoperative follow-up in Southwest Hospital, the significance of hepatolithiasis and stricture in reoperation of the biliary tract was analyzed (Huang 2014). It was first pointed out that the residual hepatolithiasis and the stricture of the hepatobiliary duct are the most common and main reasons for the failure of surgical treatment for hepatolithiasis in China; it can cause hyperplasia and atrophy, complicate design, and further increase the difficulty and risk of reoperation of biliary tract surgery. Therefore, various innovative surgical methods of portal cholangiojejunostomy have been developed. Since then, with the continuous improvement of liver surgery technology and medical technology, hepatectomy in the treatment of hepatolithiasis has progressed. Studies on hepatobiliary perfusion, especially microcirculation, causes, and control of biliary bleeding, surgical treatment of end-­ stage biliary diseases have also steadily deepened understanding. Systematic studies on the principles and methods of surgical treatment for benign biliary diseases such as hepatolithiasis, and the application of a series of surgical methods such as hepatectomy and repair of high bile duct stricture, have greatly improved treatment outcomes. These researches have promoted the diagnosis and treatment of hepatolithiasis. Because of their contribution to research on hepatolithiasis, the team of Academician Huang Zhiqiang won the first prize of The Millennial National Science and Technology

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_12

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Progress Awards. In 2007, the Department of Biliary surgery of the Chinese Medical Association organized and published the “Guidelines for the Diagnosis and Treatment of Hepatolithiasis.” In 2013, the expert consensus on the laparoscopic treatment of hepatolithiasis was formulated and published by the Committee of minimally invasive Surgeons of the Chinese Physicians Association, which further promoted the standardized diagnosis and treatment of hepatolithiasis in China. Despite the consensus on treatment, not every hospital can have the well-developed infrastructure, clinical, surgical, and technical expertise required for the effective diagnosis and treatment of hepatolithiasis. The main reason is that although the imaging evaluation of hepatolithiasis has developed considerably, some deficiencies remain. B-ultrasound, CT, and MRI have their advantages in the diagnosis of hepatolithiasis, but their shortcomings are obvious. B-ultrasound can detect dilated biliary tract and calculi; however, it is challenging to show the location of bile duct stenosis due to many factors and poor image quality. CT and MRI can comprehensively display the distribution of hepatolithiasis, dilatation of bile duct system, and pathological changes of the hepatic parenchyma, but both of them are two-dimensional tomographic black-and-white images. Generally, it is difficult to show the location of biliary stricture directly, nor can we find stones with similar density to hepatic parenchyma. Thus, an experienced specialist is required to continuously observe the CT images of each period to form a complete stereoscopic image. Invasive direct biliary imaging examinations such as ERCP and PTC have the risk of inducing complications such as acute cholangitis; and they cannot observe the pathological changes in the intrahepatic bile duct above the narrowed bile duct segment and the extrahepatic bile duct; nor the relationship between the vessels. The analysis and judgment of hepatolithiasis need to be combined with other examination methods. In particular, the above methods displayed two-dimensional images unsuitable for objective 3D visualized imaging. It is difficult to accurately visualize the liver tissue section with narrowed hepatobiliary duct lesions that need to be resected in vivo, and adjacent relationships with the surrounding vessels before the operation. In the past, the understanding of the inter-relationship between intrahepatic blood vessels and bile duct was mainly obtained from the study of the vascular casts of autopsy specimens. Although representing the basic situation, this method cannot fully reflect the personalized characteristic of the living body because it is derived from corpses. Surgeons’ judgment and surgical planning are based on the subjective and comprehensive conception of the spatial position of the tissues and organs, which presents great ambiguity and uncertainty. For complex hepatolithiasis, especially when associated with high bile duct stricture, or/and atrophic hyperplasia syndrome; the accurate grasp of variations of the biliary system,

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portal vein, hepatic artery, and hepatic vein, as well as the anatomic relationship between them, intrahepatic stones and narrow biliary ducts; has decisive significance in formulating the surgical planning for conventional hepatectomy. Therefore, the high uncertainty of the complicated condition of hepatolithiasis before the operation and insufficient evaluation, limits the effective implementation of radical therapy. As Prof. Dong et al. (2017) said, “Due to the limitations of theory and technology in the past, it was difficult to remove the benign lesions and malignant tumors involving the intrahepatic bile duct and liver parenchyma entirely, thus the cure of disease could not be achieved. The effect of surgery only remains at the level of ‘relieving symptoms’. Surgical treatment of intrahepatic bile duct lesions is a century-­long challenge in the field of abdominal surgery.” In the twenty-first century, the world has entered a new era of biological intelligence information with the rapid development of digital technology. The integration of surgery, anatomy, imaging, computer technology, and digital information engineering technology; which has promoted the emergence of 3D visualization technology of hepatolithiasis. In the past 10 years, the clinical practice in many hospitals has fully confirmed the unique and superior technical guidance and support role of 3D visualization technology in the accurate diagnosis and treatment of hepatolithiasis, which can help surgeons to achieve the “cure effect” (Fang et al. 2013). In January 2017, “Expert consensus on precise diagnosis and treatment of hepatolithiasis guided by 3D visualization technology,” jointly formulated by the Digital Medical Branch of the Chinese Medical Association and the Digital Medicine Clinical Surgery Committee of the Chinese Research Hospitals, was officially released, indicating that it has become a mature and advanced medical technology that can be popularized and standardized in China. This chapter focuses on the application of 3D visualization technology in the accurate diagnosis and treatment of hepatolithiasis.

12.2 Preoperative Imaging of Hepatolithiasis The formulation of a reasonable surgical approach requires an accurate preoperative diagnosis. The basis of preoperative treatment planning for hepatolithiasis mainly includes imaging diagnosis, evaluation of liver physiological reserve function, and judgment of the patient’s general condition. Among them, imaging diagnosis is the most critical, which is crucial to the formulation of surgical plans and surgical effects. Currently, the main imaging techniques for the diagnosis of hepatolithiasis include B-ultrasound, CT, MRI, ERCP, PTC, postoperative biliary drainage tube angiography, and choledochoscopy. However, each of them has its own advantages and limitations, so it is difficult to obtain a comprehen-

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sive diagnosis by a single examination. Thus, the combination of more than one imaging examination is often required to achieve the purpose of correct diagnosis.

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not, and whether the distal bile duct is dilated. The latter can be manifested as a strip-like branched low-density shadow parallel to the enhanced portal vein. Isodense calculi in the dilated intrahepatic bile ducts show no enhancement of strip-­ like or spot-like isodense shadow. The distal bile ducts are 12.2.1 Imaging slightly dilated, which is difficult to discern on CT. It is necessary to make a repeated observation of thin-layer CT Ultrasound examination has great value in the diagnosis of enhanced scanning and carefully measure whether the CT hepatolithiasis. Featured as noninvasive, inexpensive, and value of plain scan and contrast-enhanced CT is increasing repeatable, B-ultrasound, suitable for the screening of stones, or not, and whether the lesions are enhanced or not, so that is the simplest initial diagnostic modality and it can show the diagnosis can be confirmed. Primarily because of the hepatolithiasis and bile duct dilatation. Stones present as characteristics of low pressure in the bile duct, it is difficult echogenic spots with an acoustic shadow behind them. to display the bile duct directly by the contrast medium, Calcification of the intrahepatic duct system also shows which is rare or through the vascular pathway. The two-­ stone-like imaging, so the diagnosis of hepatolithiasis can dimensional CT image is always the bottleneck in the spatial usually be made when marked bile duct dilatation peripheral diagnosis of the stone and the stricture of the bile duct. In to the stones is seen (Sakpal et al. 2009). B-ultrasound is also general, it is difficult to display the location of biliary stricvaluable in the localization diagnosis of hepatic abscess and ture directly, so it cannot completely cover the distribution of intrahepatic cholangiocarcinoma caused by hepatolithiasis; stones, location of bile duct stricture, location of bile duct however, the imaging effect on the latter is not as good as stenosis, and display of bile duct tree. 3D reconstruction of that of CT and MRI.  B-ultrasound has a high diagnostic the bile duct can also be carried out by the CT image post-­ value for hepatolithiasis falling off to the common hepatic processing workstation. However, the 3D reconstruction duct and common bile duct. The main disadvantage is that an images obtained are only the images of a particular vascular overall image of the biliary tree cannot be adequately pro- phase. Clinicians can only be provided with 2D flat films, not vided and B-ultrasound is not as intuitive as CT and MRI, the true 3D images, with which is challenging to visualize especially, less sensitive for hepatic parenchyma lesions the stereoscopic relationship between the third stage blood (usually hepatic fibrosis) caused by biliary stricture and hep- vessel and the liver and bile duct tree simultaneously. The atolithiasis and for biliary stricture lesions. B-ultrasound is typical “honeycomb sign” can be observed by CT enhancedependent on the proficiency of the operator. Therefore, ment in the diagnosis of hepatic abscess complicated with although it can be considered as the preferred primary exam- hepatolithiasis. Separation enhancement is most evident in ination in general, other imaging examinations are still nec- the arterial phase, and the degree of enhancement decreases essary to determine the condition before surgical treatment. in the portal vein phase and delayed phase. The degree of The sensitivity and accuracy of CT in the diagnosis of enhancement of the delayed period decreased; peripheral hepatolithiasis are higher than those of B-ultrasound. CT can inflammation and congestion produced a noticeably patchy show the location of hepatic hilum, dilatation of bile duct, as enhancement in the arterial phase, and various atypical manwell as hypertrophy and atrophy of the liver. By systemati- ifestations may occur during the delayed phase, which are cally observing all levels, we can understand the distribution difficult to diagnose. Complicated cholangiocarcinoma may of stones in the intrahepatic bile duct and the pathological present various solid, cystic, and solid lesions, often accomchanges of liver parenchyma. CT plain scan can show high-­ panied by distally dilated intrahepatic bile duct and enlarged density calculi, which are displayed as a corded, round, and hilar lymph nodes, but often without specificity, which needs nodular shape in the course of the intrahepatic bile duct. Its to be evaluated in conjunction with other examinations. CT value varies according to the composition and calcium On Plain MRI, T1- and T2-weighted images can show content of the calculi. Generally speaking, high calcium con- hepatolithiasis, mostly strip, round, nodular low signal, or tent calculi have high CT value, which can clearly show the no signal shadow. According to the different components of calculi shadow, while calculi with equal density and low-­ the stone, T1-weighted can be a low signal, iso-signal, or density display poorly because of low calcium content. CT hyperintense, and the signal value of the calcium-containing plain scan has some limitations in the diagnosis of complica- stone is low. On MRI plain scan, the shape of bile duct dilations of hepatolithiasis, such as hepatic abscess and intrahe- tion can also be observed at the distal end of the stone, patic cholangiocarcinoma. Both showed homogeneous or which is shown as long strip T1 and long T2 signal. The heterogeneous low-density lesions. Enhanced CT scan can diagnosis of hepatolithiasis and choledocholithiasis can also be used as a supplement to CT plain scan in the diagnosis of be confirmed by MRI plain scan. The most significant hepatolithiasis and its complications. It can better reveal the advantage of MRI combined with MRCP is that it can dislocation of stones, whether the adjacent wall is thickened or play the intrahepatic bile duct tree in multiple directions and

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accurately judge the distribution of intrahepatic stones, the location and extent of biliary stenosis and dilation as well as liver parenchymal lesions. The limitation of MRI is that its spatial resolution is not as good as that of CT.  On the T2-weighted image, the signal of bile is long, and the abnormal signal of small stones is easily “submerged.” MRI is not as clear as CT and B-ultrasound in showing calculi. On MRI, small stones are difficult to find, and the stenosis of the bile duct is not as clear and accurate as the direct cholangiography on MRI. 3D screenshots of CT and MRCP biliary system are not true 3D images, and it is difficult to simultaneously visualize the stereoscopic anatomy of the biliary system and other intrahepatic ducts, especially that of the portal vein system. During contrast-enhanced MRI scanning, although the arteries, portal vein, and hepatic parenchyma were enhanced in each phase, the stones were not enhanced, and the stones without enhancement were often difficult to discern. Therefore, contrast-­enhanced MR imaging is mainly used in the diagnosis of complications of hepatolithiasis. For example, dynamic contrast-enhanced MR (DCE-MR) imaging can help clearly display at a distinct arterial phase not only images of multiple arterial, venous, and delayed phases, but also the “cluster sign” of hepatic abscess, as well as granulomatous wall and hyperemia around it accompanied by hepatolithiasis. The internal structure of the complicated solid cholangiocarcinoma differs from the “cluster sign” in showing as an irregular mass with delayed enhancement. There are cystic components between solid lesions, which serve to distinguish from the “cluster sign.” Invasive direct biliary imaging examinations such as ERCP and PTC are valuable in the diagnosis and treatment of intrahepatic cholelithiasis, but they are not the first choice because of the possibility of inducing complications such as acute cholangitis.

12.2.2 Other Auxiliary Examinations 12.2.2.1 Biliary Manometry Biliary manometry can be used to determine whether bile excretion is normal. It is not of great clinical significance in all scenarios involving intrahepatic cholelithiasis, however, for stones near the porta hepatis of the left and right hepatic ducts with bile duct stricture, the phenomenon of bile duct dilatation, bile retention, and increased bile duct pressure caused by inadequate bile excretion can be observed. At present, according to the condition of the disease, electronic

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biliary manometry should be selected to accurately measure the pressure in the bile duct.

12.2.2.2 Cholescintigraphy Technetium-99m (99mTc) is commonly used in radionuclide scanning. After intravenous injection, it is absorbed by the mononuclear phagocyte system and excreted into the biliary tract. 3D images can be obtained by layering and fixing points during scanning, and the relationship between the images and adjacent structures can be displayed, which provides a good basis for diagnosis. However, the diagnosis of intrahepatic bile duct stones is not ideal. 12.2.2.3 Selective Celiac Arteriography Selective celiac arteriography can be used to observe the presence of displacement, compression, interruption, and abnormal vascular shadows in the arteries. It is useful in the differential diagnosis of hepatobiliary and gallbladder cancer, but the diagnosis of intrahepatic cholelithiasis is not ideal. Moreover, arteriography requires specific equipment, complicated operation, and highly technical conditions, so it is not the first choice for intrahepatic cholelithiasis. In summary, various imaging examinations have their advantages and limitations in the diagnosis of hepatolithiasis. Therefore, for complicated cases of hepatolithiasis, it is often necessary to evaluate them comprehensively in combination with various examinations in order to obtain more objective diagnostic results and formulate surgical treatment strategies.

12.3 Acquisition of High-Quality Submillimeter CT Data The emergence of digital medical technology, represented by 3D visualization of liver and biliary tract and 3D printing technology, provides a new method for accurate preoperative evaluation of hepatolithiasis. 3D visualization technology is based on multi-slice CT enhanced thin-layer scan data. For patients who are diagnosed with hepatolithiasis by B-ultrasound and intended for establishment of a 3D visual model, the thin-section CT scanning technique is used to collect enhanced image data of the upper abdomen. The quality of the data in the plain, arterial, portal, and hepatic venous phases, directly affects the accuracy of the subsequent 3D visualization model of the hepatolithiasis.

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12.3.1 Collection Equipment 64-row spiral CT-PHILIPS Brilliance 64-, 256-, or 320-slice CT can be used. A MEDRAD double-barrel high-pressure syringe (USA) is adopted. The image post-processing workstation is the MxView workstation that comes with the PHILIPS Brilliance 64-slice spiral CT. Scanning parameters: voltage 120 kV, current 300 mAs, rotation time 0.5 s, pitch 0.984, and layer thickness 5 mm.

12.3.2 Preparation for Scanning The patient is orally administered with 500–1000  ml of freshwater 20–30  min before the examination and another 500 ml before scanning to fill the gastrointestinal tract (as a negative contrast agent). The patient is trained to breathe to maximize the control of artifacts caused by respiratory movement.

12.3.3 Plain Scan High-resolution volumetric scanning in the submillimeter state. The patient is placed in a supine position with a routine scan in the direction of head to foot. The scanning range is from the top of diaphragm to the lower edge of the liver, and the scanning condition is 120 kV, 300 mAs; 0.625 × 64 rows of detectors are combined, with 5 mm of thickness, 5 mm of interval, 0.984 of pitch, 0.5 s of bulb rotation, 40–50 cm of scanning field of vision, 512 × 512 of matrix. A routine upper abdominal plain scan is performed.

12.3.4 Dynamic Enhanced CT Scan After the plain scan, the contrast agent is injected into the cubital vein (with cannula needle), the injection rate is 5 ml/s with a double tube CT high-pressure injector. The contrast agents are high concentration of Nonionic iodipin 370 (370 mgI/ml) or iopromide 370 (370 mgI/ml). At a dose of 1.5 ml/ kg, the tube is washed with 50  ml of normal saline after injection of the contrast agent. The scanning conditions are the same as that of the plain scan. The scanning delay is 20 ~ 25 s in the arterial phase and 50 ~ 55 s in the intravenous

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phase. After scanning, the enhanced raw data is applied to perform the thin layer reconstruction of 0.67  mm with an interval of 0.33 mm, and the image data is transferred to the MxView workstation.

12.3.5 Acquisition of Thin-Slice CT Data On the MxView diagnostic workstation, all the data is recorded by CD-ROM, including the data of liver and bile duct stones during plain scan phase, arterial phase, portal venous phase, and hepatic venous phase, all in the format of DICOM 3.0.

12.4 Reconstruction of 3D Visualized Model for Hepatolithiasis Thin-slice CT data are processed by image workstation and imported into MI-3DVS for program segmentation and reconstruction. By adjusting the transparency of the liver, the structure of the liver, hepatic artery, hepatic vein, and the primary, secondary and tertiary branches of the portal vein are displayed, so do the stricture of the biliary tract and the dilated bile duct of the first to fourth grade; the size, shape, and distribution of the stones are also displayed. Through the rotational observation of the model, the spatial position relationship of each pipeline structure is clearly understood.

12.4.1 Image Registration Adjust the scanning sequence of each phase. The original CT images are read with a DICOM viewer. These images are registered, converted into BMP format, and saved in a new folder (Fig.  12.1). In the MI-3DVS, the adaptive region growth algorithm is used to segment the liver sequence, and the 3D dynamic region growth method is used to perform automatic segmentation of the liver pipeline system. It has the advantages of high speed and good accuracy and overcomes the shortcomings of manual segmentation. The segmented data can be reconstructed quickly by using the moving cube algorithm of surface rendering, which is beneficial to the research of visual simulation surgery.

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a

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Fig. 12.1  Image registration. (a) CT images are read with a DICOM viewer; (b) images are converted and saved as BMP format files in the DICOM viewer; (c) BMP images of left intrahepatic bile duct stones

with atrophy; (d) BMP images of left intrahepatic bile duct dilatation and calculi

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concretion in left liver

d

Fig. 12.1 (continued)

12.4.2 Image Automatic Segmentation and 3D Reconstruction

• The contour of the liver was clear, and the left lateral lobe was atrophied and deformed (Fig. 12.3f).

The patient’s BMP data were imported into the MI-3DVS system. Then the 3D model was automatically segmented and reconstructed with the same method. Finally, the 3D model was output in STL format (Fig.  12.2a–h); the STL format of the model containing hepatolithiasis and liver systems were imported into the FreeForm Modeling System to be processed and smoothed. The senses of layering and noise were also removed. A 3D model of each system (Fig. 12.3a– h) and a hepatobiliary model was created (Fig. 12.4). The abdominal aorta and its branches, hepatic artery, and left hepatic artery, right hepatic artery, and its subordinate branches are all clearly displayed (Fig. 12.3a).

The above method was the procedure for 3D reconstruction in the past. Now, an optimized 3D visualization system for abdominal medical images is used. In the process of 3D reconstruction, the software can directly read the original DICOM data of the patient (no format conversion is required) and then carry out automatic registration and system reconstruction, which has dramatically improved the working efficiency.

• Portal vein phase: The main portal vein and grade 5 branches are well displayed. The splenic vein and superior mesenteric vein can be seen (Fig. 12.3b). • Hepatic vein phase: In the absence of hepatic atrophy and cholangiocarcinoma, the main trunk of the hepatic vein showed well. Normally, the branches of the hepatic vein can be displayed. In this case, the left hepatic vein cannot be clearly displayed due to the atrophy and deformation of the left lateral lobe of the liver, resulting in the observed variation of the left hepatic vein (Fig. 12.3c). • Bile duct dilatation of the left extrahepatic lobe can be seen in the reconstructed biliary system (Fig. 12.3d). • Left intrahepatic cholelithiasis (Fig.  12.3e) can be seen when the transparency of the bile duct is set at 25.

12.5 3D Visualized Vascular Classification The liver, biliary tract, stones, and intrahepatic blood vessels were observed and analyzed based on the obtained 3D visualized images of the individualized liver, vessels, stones, and peritoneal vessels, and surrounding organs. For patients without liver atrophy, hypertrophy or biliary cirrhosis, 3D visualization of hepatic artery classification, and hepatic vein classification (see Sect. 16.3); 3D visual portal vein classification can be divided into the following 5 types.

12.5.1 Classification of Portal Vein Branches Normal Type  The main portal vein was divided into left and right branches at the porta hepatis (Fig. 12.5).

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a

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Fig. 12.2  Automatic image segmentation. (a) BMP data are imported into the MI-3DVS for segmentation; (b) 3D reconstruction is performed in the MI-3DVS; (c) segmentation of the liver; (d) segmentation of left intrahepatic bile duct dilation; (e) segmentation of left intrahepatic bile

duct stones; (f) segmentation of the arterial system; (g) segmentation of the portal vein system; (h) segmentation of hepatic and inferior vena cava systems

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Fig. 12.2 (continued)

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Fig. 12.2 (continued)

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g

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Fig. 12.2 (continued)

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b The proper hepatic artery

The main portal vein

The gastroduodenal artery

The right hepatic duct

The right hepatic vein

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The middle hepatic vein

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The left hepatic The common hepatic duct

The left hepatic vein

The gallbladder

The right hepatic duct

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The calculus

Left hepatatrophy

The left hepatic duct The common hepatic duct The gallbladder

h g

The hepatic vein The hepatic artery The bile duct The portal vein

Fig. 12.3  3D models of each system. (a) The reconstructed arterial system; (b) the reconstructed portal vein system; (c) the reconstructed hepatic vein and inferior vena cava; (d) the reconstructed biliary tract; (e) the calculus of the bile duct is observed in the left outer lobe when

the transparency of the biliary system is 0.5; (f) Atrophy of left outer lobe is observed in the reconstructed liver; (g) the 3D model when the liver transparency is 0; (h) the 3D model of the hepatic internal structure is displayed when the liver transparency is 0.5

Type I Variation  The portal vein was divided into the left branch, right anterior branch, and right posterior branch at the porta hepatis (Fig. 12.6).

Type II Variation  Portal vein first issued the right posterior branch, then moving upward to be divided into the right anterior branch and the left branch (Fig. 12.7).

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Fig. 12.4  The 3D model when the liver transparency is 1

LT RA

RA RP

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Fig. 12.5  Normal type Fig. 12.6  Type I

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Fig. 12.7  Type II Fig. 12.9  Other variations

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Fig. 12.8  Type III

Type III Variation  The right branch of the portal vein was horizontally divided into an anterior branch and posterior branch (Fig. 12.8). Other Variations  The absence of the left branch of the portal vein; special variations: left branch of portal vein came from the right anterior branch (Fig. 12.9). In patients with liver atrophy, hypertrophy, or biliary cirrhosis, 3D visualization and evaluation of liver vascular are particularly crucial for selecting surgical methods as well as reducing the incidence of surgical complications and risk because of its pathological changes.

12.6 I ndividualized Liver Segmentation and Volume Calculation for 3D Visualization of Hepatolithiasis In 1954, Couinaud (1954) divided the liver segment according to the distribution of the liver Glisson system and the course of the hepatic vein and proposed a relatively complete eight-segment method. He divided the liver into left and right halves, four lobes, and eight functional segments. Each liver segment can be considered as a functional anatomical unit of the liver. The Couinaud segmentation classification has become the anatomical basis of liver imaging and liver surgery and has been widely used in clinical practice. However, it also has apparent defects because it is the research result of in  vitro liver casting, and its orientation term is for the ­desktop, so it does not accord with the actual situation of in  vivo liver. Moreover, with the development of imaging techniques, more and more studies show that only some of the liver segments accord with Couinaud classification due to the variation of hepatic vein and portal vein branches. In addition to physiological changes, in patients with complex hepatolithiasis, the portal vein is compressed and deformed due to dilatation or inflammatory changes of the biliary system, resulting in local liver tissue nutrition deficiency and fibrotic atrophy. In contrast, the healthy liver exhibits compensatory proliferation, leading to atrophy and hypertrophy of the liver, and even hepatic portal transposition. The hepatic segment with hepatolithiasis was different from that of a healthy liver. The hepatic vein and portal vein system (Figs.  12.10, 12.11, 12.12, 12.13, 12.14, 12.15,

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Fig. 12.12  Staining of Segments V, VI, VII, and VII Fig. 12.10  Individualized segmentation

Fig. 12.11  Staining of Segments II, III, and IV Fig. 12.13  Overall view of segmentations

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Fig. 12.14  Segments II, III, IV, V, and VII

Fig. 12.16  Overall view of s hepatic segments

Fig. 12.15  Hypertrophy of segments V and VII, and contraction of segments VI and VII

12.16, and 12.17) are deformed, as the branches of the portal vein in adjacent liver tissue enlarge to compensate for the deformations of the hepatic and portal veins caused by stones. As a result, portal vein and hepatic veins deviate from their normal paths, and are mostly deviated from the traditional Couinaud segment. Liver atrophy and hypertrophy or liver transposition were observed. In this case, surgi-

Fig. 12.17  Stones at segments III, IV, V, VI, VII, and VII

cal resection, according to the traditional Couinaud segmentation, will inevitably lead to uncertainty of the cutting edge, thus affecting the therapeutic effect. Therefore, the preoperative 3D visualization of individualized liver

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segmentation in patients with hepatolithiasis has important guiding significance for the diagnosis and formulation of surgical methods.

12.6.1 Semiautomatic Liver Segmentation The reconstructed STL format was imported into the FreeForm Modeling System. After smoothing and denoising, the liver was translucent, and the individualized liver segmentation was performed according to the blood flow topological relationship (Fig. 12.18). The liver segments of each functional area were determined by the independent portal vein blood supply and hepatic venous reflux, and each segment of the liver was divided into different colors for comparison.

12.6.2 Hepatic Segment for Hepatolithiasis Through 3D rotational observation of portal vein and hepatic vein, the liver was divided into three, four, or even five sections according to the branches of the hepatic vein. Then the portal vein, biliary tract, and hepatic vein were registered to observe the relationship between the portal vein and bile duct branches in the hepatic veins (Figs. 12.19, 12.20, 12.21, 12.22, 12.23, 12.24, 12.25, 12.26, 12.27, 12.28, 12.29, and 12.30). The segments were marked with different colors (Figs.  12.10, 12.11, 12.12, 12.13, 12.14, 12.15, 12.16, and 12.17) to complete the individualized liver segmentation. The color of each segment was hidden or transparent to some degree. The stones and bile ducts were displayed separately or simultaneously. The distribution of stones and bile duct lesions in each hepatic segment can be clearly observed by rotating observation at different angles (Figs. 12.31, 12.32, 12.33, 12.34, 12.35, and 12.36). The precise localization diagnosis of stones and bile duct lesions can be made. The main factors to be considered comprehensively during surgery include the following aspects: the blood supply system (hepatic artery and portal vein) of the site to be resected, the reflux system (hepatic vein) of the remaining liver, and the remaining liver volume. The 3D reconstruction image can observe the blood supply artery, portal vein, and refluxing hepatic vein of the site to be resected and measure the distance between it and the secondary branch and tertiary branch of the hepatic artery and portal vein. Therefore, whether the surgical procedure is regular hepatic segment hepatectomy or irregular hepatectomy, and whether residual hepatic vein reflux is affected, can be determined. 3D reconstruction images showed the branches of the portal vein and hepatic artery at more than three levels and clearly showed the 3D morphology of three sets of the vascular system in the liver, and their spatial anatomical relationship with the site to

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be excised. Individualized liver segmentation and volume measurement are ensured. Based on the principle of Couinaud segmentation, the 3D visualized liver segmentation function was adopted, which accords with the anatomical characteristics of the individualized portal vein. It can accurately locate the liver segment where the stone is located, as well as calculate the volume of the whole liver, the liver segment where the stone is located, and the residual liver segment; thus providing an accurate basis for the evaluation of liver volume.

12.7 C  linical Diagnosis of Hepatolithiasis with 3D Visualization Appropriate disease classification can not only reflect the anatomical features and pathophysiological changes of diseases but also guide the treatment. The main pathological features of hepatolithiasis are biliary obstruction, infection, destruction, and proliferation of hepatic parenchyma. Due to the dilatation of the intrahepatic bile duct, thickening of the wall, proliferation of fibrous tissue, and massive infiltration of inflammatory cells, the portal vein branches are compressed, distorted, narrowed, blood flow is decreased and the corresponding hepatic parenchyma atrophied. The compensatory hypertrophy of normal liver tissue forms liver atrophy-­ hypertrophy syndrome. Moreover, cholestasis can also cause complications such as biliary tract infection, biliary liver abscess, acute suppurative cholangitis, subphrenic abscess, biliary fistula, and biliary bleeding. The above pathological changes and the location of the stones and diseased bile ducts have become the main considerations for the classification of hepatolithiasis. In the past, hepatolithiasis classification was based on stone component classification, Nakayama classification, and Tsunoda classification. In 2007, the Biliary Surgery branch of the Chinese Medical Association formulated and issued “Guidelines for Diagnosis and Treatment of Hepatolithiasis” (2007), In the guideline, based on (a) the clinical manifestation of the patient as well as conditions such as the distribution of stones in the liver, (b) the degree of pathological changes of the corresponding hepatic duct and liver, and (c) the complication of extrahepatic bile duct stones, hepatolithiasis was divided into two main types: type I and type II. Type I is called regional type, with stones localized in one or several segments along the intrahepatic bile duct tree, often accompanied by stenosis of the hepatic duct and atrophy of the affected segments; Type II was divided into three subtypes according to the hepatic parenchyma lesions: type II a: diffuse type, without obvious fibrosis and atrophy of the hepatic parenchyma. Type II b: diffuse type with regional fibrosis and atrophy of the hepatic parenchyma, usually accompanied by stenosis of the main hepatic duct in

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Fig. 12.18 Individualized liver segmentation. (a) Individualized hepatic segments (segment 5); (b) individualized hepatic segments (segment 7); the arrow points to segment 1; (c) individualized hepatic

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Fig. 12.19  Distribution of portal vein in four hepatic vein regions

Fig. 12.21 Anatomical relationships among the biliary tract, portal vein, and hepatic vein

Fig. 12.20  Spatial anatomy after registration of portal vein and biliary tract

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the atrophy of the liver; Type II c: diffuse type, accompanied by extensive fibrosis of hepatic parenchyma resulting in secondary biliary cirrhosis and portal hypertension, usually with severe stricture of the bile duct below the right and left hepatic duct or confluence. At the same time, the patients with extrahepatic cholelithiasis are divided into three subtypes according to the functional status of Oddi sphincter: Ea: Oddi sphincter was normal and Eb: Oddi sphincter relaxation. Ec: Oddi sphincter stenosis. The criteria in this guideline will help clinicians by providing a classification of complicated hepatolithiasis, to standardize the diagnosis and treatment according to the corresponding treatment plan of each type. The results of prospective and retrospective clinical studies can be summa-

The hepatic vein

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Fig. 12.22  Hepatic and portal veins

rized and analyzed according to unified criteria so that the conclusions are more realistic and objective and have important guiding significance for clinical research and treatment. In 2017, a digital clinical classification of hepatolithiasis was established through the combination of the 3D visual imaging features of hepatolithiasis and the “Expert consensus on precise diagnosis and treatment of hepatolithiasis guided by three-dimensional visualization technology” formulated by the Digital Medicine branch of the Chinese Medical Association and the Digital Medical Committee of Clinical Surgery of the Chinese Research Hospital Society. This expert consensus was based on the “Guidelines” (2007 edition). The digital classification of hepatolithiasis under the guidance of 3D visualization is set based on the comprehensive evaluation of location (L) of stones in different liver segments, the specific location of biliary stenosis (S) or distention (D), and whether it is associated with hepatic atrophy (A) or cirrhosis (C) because the stereoscopic morphology and relationship of intrahepatic “bile duct tree” and “vascular tree,” the size and distribution of stones in various hepatobiliary ducts, the degree and extent of biliary stenosis, the variation of blood vessels and the atrophy of the liver can be displayed in the stereoscopic model constructed by 3D visualization technique. The specific classification is shown in Figs. 12.37, 12.38, 12.39, 12.40, 12.41, 12.42, 12.43, and 12.44. For example, Fig.  12.37: hepatolithiasis LII, III, VI, VII, Sleft and right hepatic duct, DII, III, VI, and VII, and C, indicating stones in the II, III, VI, and VII segments of the liver, the left and right hepatic bile duct stenosis, II, III, VI, VII bile duct dilatation, and liver cirrhosis.

Fig. 12.23  Biliary tract and portal vein The dilated biliary ducts and calculus

The portal vein

12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.24 Stereoscopic anatomy of the biliary tract, hepatic vein, and portal vein

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The dilated biliary ducts

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Fig. 12.25 Stereoscopic anatomy of the portal vein and hepatic vein

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The digital classification is concise, convenient, practical, accurate, and fast; this classification can be generated immediately after the preoperative 3D evaluation. It further standardizes the establishment of a 3D visual model of hepatolithiasis, which is helpful for clinicians to quickly establish a clear and accurate understanding of the patient’s basic condition. Therefore, the clinical classification and management of cholelithiasis based on the “Guidelines”

(2007 edition) can be correctly understood and implemented. This method provides a new strategy for the accurate diagnosis and treatment of intrahepatic cholelithiasis. For example, Fig. 12.44 can clearly show that right hepatolithiasis in segments V, VI, VII, and VII, accompanied by right hepatic stenosis, and atrophy of segments VI and VII, which can guide clinicians to perform precise anatomical right hepatectomy.

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Fig. 12.26 Stereoscopic anatomy of the portal vein, bile duct, and calculus

The dilated biliary ducts and calculus

The portal vein

Fig. 12.27 Stereoscopic anatomy of the bile duct, stone, and vascular system

The hepatic vein

The dilated biliary ducts and calculus

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Fig. 12.28 Stereoscopic anatomy of the portal vein and hepatic vein

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Fig. 12.29 Stereoscopic anatomy of the portal vein and biliary tract

The dilated biliary ducts and calculus

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Fig. 12.31  Stones in segments II, III, IV, VII, and VII

Fig. 12.32  Stones in segments II, III, and IV

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The stone

Fig. 12.35  Stones are seen when segments V and VII are removed

Fig. 12.33  Stones in segments VI and VII

Fig. 12.34  Stones are seen when segment II is removed

Fig. 12.36  Stones are seen when segments VI and VII are transparent

264 Fig. 12.37 Hepatolithiasis LII, III, VI, VII, Sleft and right hepatic duct, DII, III, VI, and VII, and C

Fig. 12.38 Hepatolithiasis; observe the relationship between the portal vein and bile duct (front view); Sleft and right hepatic duct and DII, III, VI, and VII

Fig. 12.39 Hepatolithiasis; observe the relationship between the hepatic artery and bile duct (superior view); Sright hepatic duct and DII, III, VI, and VII

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12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.40 Hepatolithiasis LII, III, VI, and VII, SII, III, right, VI, and VII, DII, III, IV, VI, and VII, C

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12.8.1 Secondary Development of Virtual Surgical Instruments and Simulated Surgery The STL format of the 3D model of hepatolithiasis and the mold of the customized surgical instrument, were imported into the FreeForm Modeling System. By using the force feedback device of the system (PHANTOM), the model could be magnified, reduced, and rotated. After the determination of the route of liver resection and activation of the virtual liver, the liver could be cut with a virtual scalpel. The hepatic artery branch and portal vein branch of the liver section could be sutured and ligated, and the hepatic vein branch and bile duct branch cut off to complete the visual virtual hepatectomy. Fig. 12.41  Hepatolithiasis LII–VII, S0, DII–VII, C0

12.8 P  reoperative Planning and Surgical Simulation The use of a 3D visual virtual system to simulate the operation of hepatolithiasis before an operation helps find the best operative approach and treatment method. The virtual simulation surgery system has advantages such as interoperability and repeatability. It can simulate and predict complex and dangerous situations that may occur in the actual operation. Through the simulation of different surgical schemes, the advantages and disadvantages of these schemes can be compared. In this way, a reasonable and individualized operation program can be selected.

12.8.2 Examples of Simulated Liver Resection for Hepatolithiasis 12.8.2.1 S  imulated Liver Resection for Left-­ Sided Hepatolithiasis The 3D model of liver and gallbladder with left hepatolithiasis was reconstructed and imported into the FreeForm Modeling System. By controlling the transparency of the liver and the biliary tract, all the structures of the liver and its internal organs can be observed and displayed, including the bile duct, hepatic artery, portal vein, hepatic vein, the abdominal aorta, and inferior vena cava. They were consistent with the true structure, especially the bile duct dilatation and multiple stones with atrophy of the left extrahepatic lobe, showing clear structure, accurate location, and fidelity to the

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Fig. 12.42  Hepatolithiasis LII, III, IV, and VI, Sleft hepatic duct, DII, III, IV, VI, and VII, C0. (a) Anterior view; (b) overall view

Fig. 12.44  Hepatolithiasis LV, VI, VII, and VII, S right hepatic duct, DV, VI, VII, and VII, C0 Fig. 12.43  Hepatolithiasis LII, III, IV, Sleft and right hepatic duct, DII, III, IV, VI, and VII, C0

12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.45  3D model of liver with different transparency. (a) 3D model when the liver transparency is 0; (b) when the liver transparency is 0.5, the 3D model of internal structure is displayed

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original two-dimensional image (Fig.  12.45a, b). Different tissue structures were rendered in different colors: the liver was reddish brown; the bile duct, green; the arterial system, red; the portal vein, purple; the hepatic vein and inferior vena cava, blue; the left hepatolithiasis, black (Figs.  12.45 and 12.46). The virtual scalpel can be used to cut the liver at will, with real-time manifestation and strong haptic feedback. The whole surgical procedure has good interactivity, immersion and operability. Surgical Procedures • Introduce the virtual scalpel and activate the virtual liver (Fig. 12.47). • When the transparency of the liver is 0.5, the left hepatic dilated bile duct and stones are shown, and the route of hepatectomy is determined (Fig. 12.48). • The process of left hepatectomy (Figs.  12.49 and 12.50a–c). • Left hepatic artery was activated and transected (Fig. 12.51a).

• The left branch of the portal vein was activated and transected (Fig. 12.52a, b). • The left hepatic duct was activated and transected (Fig. 12.53a–c). • Activate the left liver, bile duct, arteries and veins, and stones (Fig. 12.54). • The left liver was observed by rotation while removing it. The stones can be displayed when the transparency of the left liver is set to 0 (Fig. 12.55a–c). • The left hepatic artery, left portal vein, and left hepatic duct were sutured respectively with a suture needle, suture line, and line knot (Fig. 12.56a–c). • The left hepatic duct, left hepatic artery, and left portal vein were sutured (Fig.  12.57), and the enlarged left hepatic section (Fig. 12.58) was observed.

12.8.2.2 V  irtual Liver Resection for Left and Right Hepatolithiasis The 3D model of liver and gallbladder with left and right hepatolithiasis was reconstructed and imported into the

268 Fig. 12.46  3D model when the liver transparency is 1

Fig. 12.47  Import the virtual scalpel and activate the virtual liver

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12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.48 Left hepatolithiasis is shown and the route of cutting the left liver is determined when the transparency of the liver is 0.5

Fig. 12.49  Follow the established cutting route and cut the liver

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Fig. 12.50 (a) The process of cutting when the liver transparency is 0.5; (b) the process of cutting when the liver transparency is 0.5; (c) The left liver parenchyma is cut off when the liver transparency is 1

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Fig. 12.50 (continued)

FreeForm Modeling System. By varying the level of transparency of the liver and bile duct, the structure of the liver and all its internal ducts can be observed and displayed. Its expression of content and the color coding of different vessels were the same as those of the left hepatectomy virtual surgery. The virtual scalpel can be used to cut the liver at will, with real-time effect and realistic haptic feedback, while the whole surgical procedure has good interactivity, immersion, and operability.

Because various 3D visualization software cannot simulate the physiological function of the liver at present, it is impossible to completely virtualize the real surgical scene, such as tissue bleeding, elastic deformation of soft tissue, real-time blood circulation of various liver tubes, and flow of bile. Therefore, the combination of morphological and functional aspects is an important research direction for the future optimization of visual simulation surgery systems.

Surgical Procedures • Introduce the virtual scalpel, activate bile duct, and open common bile duct (Fig. 12.59). • Choledocholithotomy for stone extraction (Fig. 12.60). • When the transparency of the liver was 0.5, the left hepatic dilated bile duct and stones were shown, and the route of hepatectomy was determined (Figs.  12.48 and 12.61). • The process of left hepatectomy (Figs.  12.62a, b and 12.63a–c). • The left hepatic artery, left portal vein branch, and left hepatic duct were sutured respectively by suture needle, suture line, and line knot (Figs. 12.64 and 12.65). • The process of partial right hepatectomy (Figs.  12.66, 12.67, 12.68, 12.69, and 12.70). • Choledochojejunostomy (Figs. 12.71, 12.72, and 12.73).

12.9 3  D Printing of Liver in the Diagnosis and Management of Complicated Hepatolithiasis 3D printing technology is mainly a rapid prototyping technology. It is based on digital model files and uses adhesive materials such as powder metal or plastics. The synthesis of objects can be constructed by layer printing. After 3D reconstruction, 3D printing of the liver can truly restore the characteristics of organs in vivo. Thus, based on 3D visualization, the liver model can be closer to reality (Fig. 12.74). Its advantages include: the location, size, shape of stones can be displayed through the physical model, and the relationship between stones and vessels can be observed in all directions; Intuitive real-time intraoperative indirect navigation is provided.

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12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.52 (a) Activation of the left branch of the portal vein; (b) Cut off the left branch of the portal vein

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Fig. 12.53 (a) Activation of the bile duct in the left liver; (b) cut off the left hepatic duct; (c) cut off the left hepatic duct

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Fig. 12.54  Activation of the left liver, bile duct, arteries and veins, and stone

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Fig. 12.55 (a) Remove the left liver; (b) remove the left liver and rotate; (c) set the transparency of removed left liver to 0, to reveal calculi

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Fig. 12.55 (continued)

3D printing technology is restricted by factors such as picture quality of CT and MRI, printing type, and printing materials. Its wide application in the clinic needs to be further explored. See Chap. 5, 3D Printing Technology, and its application in biliary surgery for details.

12.10 Precise Treatment of Hepatolithiasis Guided by 3D Visualization Technology At present, surgery is the main treatment for hepatolithiasis. Because of the wide distribution of stones, the different locations and degrees of bile duct stricture and dilation, the operation methods are various. Meanwhile, some patients with long-term pathological changes may suffer from atrophy or hypertrophy of liver parenchyma, complicated by biliary cirrhosis, portal hypertension, biliary tract infection, and liver abscess, or even have stones associated with intrahepatic bile duct cancer, which further leads to the complexity and variety of surgical schemes. Based on the reasons above, this section elaborates on the individualized treatment of hepatolithiasis guided by 3D visualization in different scenarios.

12.10.1  Targeted Lithotripsy for Hepatolithiasis Under Laparoscopy and Choledochoscopy Assisted by 3D Visualization There is a strong segmental distribution of stones in the liver. It is generally believed that only after removing the hepatic parenchyma containing stones, can the stones be completely removed, and the lesions cleared. The diagnostic value of CT, MRCP, and ERCP for hepatolithiasis is described in detail in Sect. 12.1. From the 3D visualization model, the images of hepatobiliary stones, which are completely faithful to the patient’s real situation, can be obtained, and the location, size, and quantity of the stones can be determined. The course of the bile duct, the location, extent, and length of the stricture, and its position relative to the whole liver is clear at a glance; 3D visual classification can clearly define the liver segments involved in regional and diffuse lesions and distinguish narrow bile duct from absolute stricture. Thus, the accurate diagnosis of hepatolithiasis can be realized, which is helpful in guiding the formulation of the surgical plan. It can greatly improve the pertinence of and reduce the unpredictability

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Fig. 12.56 (a) Import stitches in FreeForm Model System; (b) suture the left hepatic duct; (c) suture the severed end of the left hepatic artery and the left portal vein

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Fig. 12.57  Suture the left hepatic duct, left hepatic artery, and left portal vein

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Fig. 12.58  Magnified view of the left liver section

Fig. 12.60  Stone forceps are used to remove bile duct stones

Fig. 12.59  Import the virtual scalpel and activate the biliary tract

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of the operation. The auxiliary treatment technique can realize the principle of “removing the lesions, extracting the stones, relieving the obstruction, completing drainage, preventing recurrence, and protecting function” in the treatment of hepatolithiasis. In recent years, 3D laparoscopy has been widely used because of its high resolution and good depth of field, which is beneficial to accurate anatomical localization, identification of various deep hepatic duct structures, fine operation, and intraoperative bleeding control. The application of minimally invasive techniques such as 3D laparoscopy and hard choledochoscope has changed the huge physiological and psychological trauma on patients caused by traditional surgical procedures through minimally invasive mini incision. Although the hard choledochoscope cannot be bent and it is difficult to explore the intrahepatic bile duct with a wide angle, it has more advantages compared with the electronic choledochoscope:

Fig. 12.61  Left hepatolithiasis is shown. The route of cutting the left liver is determined when the liver transparency is 0.5

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Fig. 12.62 (a) Begin by cutting the liver along a defined path (b) Left hepatic vein is sutured when the liver transparency is 0.5

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Fig. 12.63 (a) The process of cutting when the liver transparency is 1; (b) the bile duct was opened and dilated for lithotomy when the liver transparency was 1; (c) during the resection of liver parenchyma, the

left hepatic artery, the left portal vein, and the left hepatic duct were activated to cut off the left hepatic parenchyma

• For some large stones, it is difficult to remove them only by using lithotripter forceps or Cook baskets, and there is a risk of bleeding caused by tearing the bile duct mucosa. At this time, pneumatic ballistic lithotripsy can be used to remove the stones easily without thermal effect, and the damage is slight. • The high pressure of hard endoscope irrigation of the bile duct is helpful for the safe and rapid discharge of crushed stones.

• Continuous suction of negative pressure is helpful for the timely discharge of contaminated bile and residual, which effectively reduces the bacterial entry into the blood during the operation and reduces the complications such as biliary tract infection. Thus, the internal environment for the recurrence of stones was cleared, and the high recurrence rate of stones was reduced. • It is relatively cheap and easy to popularize.

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Fig. 12.65  Suture the broken end of the left hepatic duct, left hepatic artery and left portal vein, and the wound surface of the liver was sutured Fig. 12.64  The left liver section was observed when the liver transparency was 0.5

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Fig. 12.66 (a) Right hepatic resection line was determined when the liver transparency was 0.5; (b) liver cutting process when the liver transparency was 1

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Fig. 12.67  The dilated bile duct was opened to extract the stone when the liver transparency was 1

Fig. 12.68  During the resection of liver parenchyma, the right hepatic artery, the right portal vein, the right hepatic vein, and the right hepatic duct were activated to cut off the right hepatic parenchyma

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Fig. 12.69  Lithotomy via right hepatic section

Fig. 12.70  Suture the broken end of the right hepatic duct, right hepatic artery and right portal vein, and the wound surface of the liver

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The hepatic vein

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The hepatic vein The dilated biliary ducts and calculus The portal vein The hepatic artery

Fig. 12.71  Jejunum was cut off for choledochojejunostomy Fig. 12.74  3D printed model of complex hepatolithiasis. Note: (1) Dark blue: hepatic vein; (2) red: hepatic artery; (3) light blue: portal vein; (4) green: dilate bile duct; (5) white: stone

Fig. 12.72 Choledochojejunostomy

Fig. 12.73 Choledochojejunostomy

The accurate operation was realized through 3D visualization guided targeted lithotripsy for hepatolithiasis under 3D laparoscopy and choledochoscopy, and the residual stone rate and recurrence rate were reduced. The combination of the three techniques further promotes the advantages of minimally invasive technique: through 3D laparoscopy, a high-­ resolution surgical vision of the abdominal cavity can be obtained from a small incision, which makes the operation more precise and helps to reduce local injury. It is convenient and fast to establish the passage through the original puncture hole into the sheath tube for the entry and exit of the hard choledochoscope. The application of choledochoscopy overcomes the blindness and limitation of traditional bile duct exploration. Combined with a 3D visual image, the lesion site can be reached quickly and clearly; and combined with various stones removal methods, it is helpful to thoroughly and repeatedly remove stones, and relieve the stenosis. On the pathological level, choledochoscopy is also beneficial for obtaining a biopsy of living tissues during surgery, to obtain pathological information more quickly and accurately, and to understand other pathological conditions comprehensively. During the operation, gauze packing is used to block the lower part of the common bile duct, which can reduce the absorption of water and toxin and ensure the safety of the operation. To sum up, 3D visualization assisted targeted lithotripsy for hepatolithiasis under 3D laparoscopy and choledochoscopy provides a safe and effective approach, and an i­ mportant technique of digital minimally invasive surgical treatment.

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12.10.2  A  natomical or Regular Hepatectomy Guided by 3D Visualization

12.10.2.4 Surgical Procedures Tracheal intubation combined with general anesthesia.

According to the pathological basis that hepatolithiasis is a type of strict intrahepatic segmental lesion, Professor Zhiqiang Huang first proposed in 1958 to treat hepatolithiasis with regular hepatectomy (1959). Since then, the clinical practice of surgical treatment of hepatolithiasis for nearly half a century has confirmed that among the treatment principles of “relieving the obstruction, removing the lesions, and completing the drainage”; regular hepatectomy, which can truly achieve the goal of “removing the lesions,” is the most important and core technique in the treatment of hepatolithiasis. However, in patients with complicated hepatolithiasis, the liver is often distorted and transposed, and the rate of variation associated with blood vessels and bile ducts is very high. It is difficult to obtain ideal portal vein and hepatic vein morphology in existing imaging examinations, so the failure of some cases to follow conventional Couinaud segments poses a challenge for regular hepatectomy. Whereas 3D visualization provides a solid and reliable 3D stereoscopic imaging technique for anatomical or regular hepatectomy; because of the relationship between the portal vein and hepatic vein in patients with various types of hepatolithiasis, and its relationship with the diseased bile duct and stones; can be clearly displayed.

For Anatomical Right Hemihepatectomy • The first hepatic portal was dissected, and the right portal vein and right hepatic artery were separated and temporarily controlled or ligated. • Free ligaments around the liver. • Common bile duct exploration. • ICG fluorescent imaging technique can be used to determine the cutting line of the liver in hospitals where conditions permit. • The other steps are the same as those for the right hepatectomy. • ICG fluorescent imaging technique was used to detect bile leakage on the left liver section (Resources 12.1 and 12.2) (Figs. 12.75, 12.76, 12.77, 12.78, and 12.79).

12.10.2.1 Indications • Child-Pugh class A hepatic function patients who need segmental/regional hepatectomy. • The corresponding hepatic lobectomy or segmental hepatectomy should be performed, if there is liver atrophy or corresponding segmental biliary stricture, no matter where the stones are located in the liver. • Intraoperative choledochoscopy and Oddi sphincter function determine whether to perform cholangiojejunostomy. 12.10.2.2 Contraindications • Patients with obvious bleeding and dysfunction. • Liver function Child-Pugh class C. • Inability to tolerate general anesthesia.

For Anatomical Left Hemihepatectomy • The first hepatic portal was dissected, and the left portal vein and left hepatic artery were separated and temporarily controlled or ligated.

Fig. 12.75  3D visualization shows right hepatolithiasis, right hepatic atrophy, compensatory hypertrophy of the left liver. Digital diagnosis: LV ~ VII, Sright hepatic duct, DV ~ VII, C0

coagulation

12.10.2.3 Preoperative Preparation and Imaging Evaluation High-quality CT images of liver and bile duct stones were collected before operation for 3D visual evaluation, liver segmentation, and volume calculation.

The right hepatic artery

Fig. 12.76  Anatomy of the first hepatic hilum, right hepatic artery transection of the common hepatic duct

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• Freeing of the ligaments around the liver. • Common bile duct exploration. • ICG fluorescent imaging technique can be used to determine the cutting line of the liver in hospitals where conditions permit. • The other steps are the same as those for left hepatectomy. • ICG fluorescent imaging technique was used to detect bile leakage on the right liver section (Resources 12.3, 12.4, and 12.5) (Figs. 12.80, 12.81, 12.82, 12.83, 12.84, and 12.85). For Patients with Stones Distributed in Segments II and III and Left Hepatic Duct Stenosis • Cholecystectomy. • Choledocholithotomy. • Resection of hepatic segments II and III. • Rapid intraoperative pathological examination of multipoint biliary ducts in the hepatic section.

Fig. 12.77  Anatomy of the right portal vein and control Fig. 12.78  Atrophy of the right liver. ICG fluorescent imaging clearly shows the dividing line of the left and right liver

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• Hepatolithiasis was removed through Section IV of the bile duct. • Left hepatobiliary stenosis was reconstructed. • Choledochoscope (soft/hard) was used to detect segment IV of the bile duct and Oddi sphincter. • Choledochojejunostomy: determined by intraoperative choledochoscopy and Oddi sphincter function (Figs. 12.86, 12.87, 12.88, 12.89, 12.90, and 12.91).

12.10.3  L  iver Resection in Special Cases Guided by 3D Visualization Technology The removal of the lesion through regular hepatectomy is difficult for patients with: diffuse stones in the left and right livers, and older age, recurrent cholangitis, multiple operations, poor general condition, insufficient residual liver volume, and insufficient liver reserve function, and even for patients who cannot tolerate extensive hepatectomy, especially in hospitals where the technical expertise is relatively limited. How to avoid multiple operations on these patients as far as possible, and strive for radical treatment in a single operation, is a difficult problem. Surgical strategy included perioperative safety measures to enhance liver reserve function and the general whole-body condition. On this ­ foundation and guided by 3D visualization technique, the method of combining regular hepatectomy, irregular hepatectomy, and choledochoscopic soft/hard lithotripsy was adopted in order to realize the basic principles of treating hepatolithiasis; while preserving remnant liver tissues to the greatest extent, to enable patients to recover safely. Cases 1 and 2: Patients with stones diffused in the left and right liver and not suitable for regular hepatectomy and segmental resection for various reasons.

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12.10.3.1 Contraindication • Patients with obvious bleeding and dysfunction. • Liver function Child-Pugh class C. • Unable to tolerate general anesthesia.

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Surgical Procedures coagulation

12.10.3.2 P  reoperative Preparation and Image Evaluation Same as before. 12.10.3.3 Surgical Procedures Case 1 Diagnosis Choledocholithiasis, L II ~ VII, S left, D IV, V, VII, AII, III, VI, VII.

Fig. 12.79  Right hemihepatectomy and choledochojejunostomy Fig. 12.80  CT showing left hepatolithiasis

• Such patients often have 2–3 or more biliary tract operations and severe hilar adhesions. Therefore, the hilar bile duct should be found along the right side of the liver. Sometimes, partial resection of the quadrate lobe of the liver or splitting of the median hepatic fissure is necessary to find the dilated bile duct above the hilar part. • Incision of the common bile duct for removal of a gallstone. • Resection of hepatic segments II and III. • Intraoperative frozen examination of the bile ducts on the left liver section. • Choledocholithotomy through segment IV. • Reconstruction of the biliary stricture is needed for patients with left hepatic biliary stricture. • Right atrophic segment/area resection. • Intraoperative frozen examination of the bile ducts on the right liver section. • Removal of stones through the right hepatic section and hilar bile duct. • Reconstruction of the biliary stricture is needed for patients with right hepatic biliary stricture. • Soft/rigid choledochoscopy was used to explore the bile duct of segment IV, right hepatic duct, extrahepatic bile duct, and Oddi sphincter. • Cholangiojejunostomy (Resources 12.6 and 12.7) (Figs.  12.92, 12.93, 12.94, 12.95, 12.96, 12.97, and 12.98). Case 2 Diagnosis Hepatolithiasis, LV, VI, VII, VII, Sright, DV, VII, VII, AVI.

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Note: Preserve multipoint biopsy of the lateral bile duct for rapid pathological examination during surgery to exclude malignant changes (Figs. 12.99, 12.100, 12.101, and 12.102).

12.10.4  T  argeted Lithotripsy and Stone Extraction Through a Sinus Choledochoscope (Hard Endoscope) Guided by 3D Visualization 12.10.4.1 Indications Patients with a history of biliary tract surgery, residual stones, recurrent hepatolithiasis, and biliary duct stent or drainage tube, can have targeted hard endoscopic lithotripsy and stone removal through the sinus duct guided by 3D visualization.

Fig. 12.81  3D visualization of the left hepatolithiasis is adjacent to the middle hepatic vein. Type LII, III, IV, S0, D left hepatic duct, II, III, and IV, C0

The left hepatic portal vein The left hepatic artery

Fig. 12.82  Anatomy of the first hepatic hilum, left hepatic artery, left hepatic portal vein, and control them

Surgical Procedures • • • • • • • •

Removal of the gallbladder. Choledocholithotomy. Liver resection of the atrophic segment VI. Intraoperative frozen examination of the bile ducts on the liver section. Removal of stones through the right hepatic section. Reconstruction of the hepatic biliary stricture. Soft/rigid choledochoscopy was used to explore the right hepatobiliary duct and Oddi sphincter. Roux-en-Y anastomosis: based on intraoperative choledochoscopy and sphincter of Oddi function (Resources 12.2 and 12.3).

12.10.4.2 Contraindication • Patients with obvious bleeding and coagulation dysfunction. • Child-Pugh class C grade of liver function. • Those who cannot tolerate general anesthesia. 12.10.4.3 Preoperative Preparation and Imaging Evaluation • High-quality CT image data of hepatolithiasis and hepatobiliary duct stones were routinely collected before the operation for 3D visualization analysis. • Direct cholangiography was performed through various drainage tubes and supporting ducts of the biliary tract. • MRCP was performed routinely before the operation. 12.10.4.4 Surgical Procedures • The Richard Wolf choledochoscope was used for the operation. • Individualized targeted lithotripsy was performed under the guidance of the MI-3DVS. • General anesthesia with tracheal intubation. • The initially placed biliary drainage catheter was pulled out, and the length of the body was recorded. The patchy guidewire was inserted into the dilator and sheath tube from the sinuses, and the indwelling dilator and sheath tube were placed along the patchy guide wire to reach the common hepatic duct or intrahepatic bile duct, leaving the sheath tube and assistant fixation. • The rigid mirror was connected with the adjustable pressure water pump, and 0.9% sodium chloride was used as a flushing solution. The rigid mirror reached the target bile duct under the guidance of the 3D model. Then a pneumatic-ballistic lithotripter was placed, and stones larger

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Fig. 12.83  Severe left hepatic atrophy; ICG fluorescent imaging clearly showing the left and right hepatic dividing lines

• Intrahepatic strictured bile ducts were dilated with soft dilators such as biliary balloons. For strictured bile ducts with solid scars, an electric knife was used to cut them off. After dilatation, the distal bile duct supporting beyond the strictured segment was placed. • Finally, extrahepatic bile duct stones were explored and removed, and the function of Oddi sphincter was observed. • T-tube and drainage tubes were retained.

Fig. 12.84  Anatomic left hemihepatectomy

than 10  mm were crushed with the pneumatic ballistics. The ballistic pressure was automatically regulated by the pump, ranging from 0.2 to 0.4  MPa. Stones were then removed by grasping forceps or Cook wire basket. Some of the smaller sediments washed out through the sheath tube with the flowing water. Biliary ducts of grade IV and above or with small bifurcation angle were removed by Cook’s basket or flushing and aspirating with water.

12.10.4.5 Attention • During the lithotripsy procedure, keep the hard lens inside the sheath pipe, and the procedure can be excited only when the stone is in contact with the gravel road. The gravel rod should be placed in the center of the stone, not in the fissure of the stone or between the stone and the bile duct wall. This helps avoid hemobilia caused by bile duct injury by the hard choledochoscope. • In the course of water flushing, the water pressure should be adjusted according to the degree of biliary inflammation in individual patients. This helps to avoid postoperative infections as it can prevent bacteria from entering the blood due to excessive water pressure. • For stones larger than 10 mm in diameter, they should not be forced to take out by lithotripters or Cook basket alone, so as to avoid hemobilia caused by laceration on mucosa. • During the whole lithotripsy process, the total water flushing volume should be controlled at 24,000  ml to 27,000  ml to avoid water intoxication (Figs.  12.103, 12.104, and 12.105).

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Fig. 12.85  ICG fluorescent imaging was used to detect biliary leakage in the right liver section

12.10.5.2 Contraindications Patients with apparent coagulation dysfunction; liver function Child-Pugh class C; inability to tolerate general anesthesia.

Fig. 12.86  CT shows stones are mainly distributed in segments II, III bile duct, and atrophy of the left lateral hepatic lobe

12.10.5  O  pen Liver Resection Combined with Targeted Lithotripsy Under Choledochoscope (Soft/Rigid) Guided by 3D Visualization 12.10.5.1 Indications • Abdominal adhesions caused by previous abdominal surgery. • Severe, multiple stenoses, or liver metastasis of the hilar biliary tube that requires bile duct plastic surgery. • Hepatectomy is necessary when there is atrophy of a liver region or segment. • Preoperative image evaluation and biochemical examination indicative of cholangiocarcinoma. • Laparoscopic hepatectomy or segmental resection is not available.

12.10.5.3 Surgical Procedures • For the patients undergoing an operation for the first time, cholecystectomy and common bile duct exploration should be performed first. • For those who have undergone biliary surgery many times, the hilar bile duct must be found along the right hepatic surface because of severe hilar adhesions. Sometimes, the partial resection of the hepatic lobe or splitting of the median hepatic fissure is required to find the dilated bile duct above the hilar. • The bile duct is cut for stone removal. • The corresponding liver segment or area resection is performed according to the clinical classification and the need for the disease. • Rapid pathological examination of the multipoint intraoperative bile duct in the liver. • Cholangiolithiasis removed through the hepatic segment section. • Plastic treatment of hepatobiliary stricture. • Choledochoscope (soft/hard) exploration of the bile duct. • Select the appropriate dilator and sheath tube according to the thickness of the bile duct. The lithotripsy and net-­ basket stone removal methods are the same as the 3D visualization technique to guide targeted hard endoscopic lithotripsy and stone removal through the sinus duct. • Finally, the extrahepatic stones are explored and removed. If the Oddi sphincter function is normal and biliary hard mirror can enter the duodenal cavity, T-tube and drainage tube should be indwelled. If Oddi sphincter is loose, cho-

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Fig. 12.87  3D modelling and digital clinical classification: LII and III, Sleft hepatic duct, DII ad III, C0

The right hepatic artery

Fig. 12.88  The right hepatic artery crosses over the common hepatic duct, and the actual operation is consistent with the 3D visualization display

ledochojejunostomy should be performed. The abdominal cavity is closed after washing (Resource 12.4) (Figs. 12.106, 12.107, 12.108, 12.109, and 12.110).

12.10.5.4 Attention • The specific technical operation precautions for choledochoscopy (soft or hard mirror) targeting gravel and stone removal are the same as for Sect. 12.10.4. • Before hepatolithiasis, temporary filling of the lower segment of the common bile duct with a gauze strip can

reduce the amount of flushing fluid entering the intestinal tract through the lower segment of the common bile duct. At the same time, continuous suction of the overflowing lavage fluid by a suction device can reduce the absorption of water and avoid the occurrence of postoperative water intoxication.

12.10.6  Percutaneous Transhepatic Choledocholithotripsy Guided by 3D Visualization in the Treatment of Hepatolithiasis 12.10.6.1 Indications • Recurrence of intrahepatic cholelithiasis after repeated operations, including biliary and intestinal drainage. • Intrahepatic and extrahepatic bile duct stones that cannot, should not, or patients who are reluctant to take other technical treatment after multiple operations. • The bile duct dilates above 0.3  cm. In principle, the thicker the bile duct is, the easier it is to puncture successfully.

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Fig. 12.89  3D modelling shows that the stones are located in segments II and III; stenosis of the left hepatic duct

Fig. 12.90  Biliary lithotomy through liver section of segment IV; plastic surgery for hepatic duct stenosis

Fig. 12.91  No residual calculi were found by postoperative direct cholangiography

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Fig. 12.92  3D visualization displays calculi in segments II and III, and parts in segment IV; the left hepatic lobe atrophy, and there is no atrophy of the liver tissue in segment IV; stones distribution in segments VI and VII, and hepatic duct is accompanied by hepatic atrophy. In this case, regular liver resection of segments II and III, irregular liver resection of segments VI and VII should be performed. It is of great value to the function of postoperative residual liver tissue. The individual surgical decision fully demonstrates the advantages of 3D visualization

Fig. 12.93  Liver resection of segments II and III

Fig. 12.94  Liver resection of segments VI and VII

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Fig. 12.95  3D visualization shows the relationship between dilated bile duct, hepatic artery, and portal vein

Fig. 12.96  3D visualization displays the size, shape, distribution of stones, and their relationship to the portal vein; digital type: LII–VII, S0, DII–VII, C0

The dilated biliary ducts and calculus

The portal vein

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Fig. 12.97  Liver resection of segments II and III, choledocholithotomy via left hepatic cross section

Fig. 12.99  Calculus in the right liver, right hepatic duct stricture associated with intrahepatic bile duct dilatation

Fig. 12.98  Irregular partial liver tissue in segment VI, and lithotomy via right hepatic cross section

• In patients with intrahepatic cholelithiasis complicated with biliary stricture, or patients who have difficulty in ERCP catheterization or failure in operation. • Simple reversible stricture of the intrahepatic bile duct.

12.10.6.2 Contraindications • Obvious bleeding and coagulation dysfunction. • The patient who was in poor condition had apparent cardiopulmonary dysfunction, could not tolerate surgery or was in critical condition. • Non-dilatation of the intrahepatic bile duct. • Liver failure. 12.10.6.3 Preoperative Imaging Evaluation CT, MRCP, or 3D visualization evaluation. 12.10.6.4 Surgical Procedures • Percutaneous transhepatic puncture of target bile duct under epidural anesthesia or general anesthesia was performed under ultrasound localization.

Fig. 12.100  Cholangiolithotomy via right hepatic cross section

• The super-smooth guide wire was put back into the bile, and the 8-16F dilator was inserted through the guidewire to expand in turn, and then sent to the sheath tube through the dilator to establish an operational channel. • Then the rigid choledochoscope was used to direct the target bile duct through the sheath tube, and the adjustable pressure perfusion pump was used to infuse normal saline into the target bile duct continuously. After the stones were located, they were removed by using a net basket, or by clamping or flushing with water after lithotripsy. Lithotripsy and 3D visualization technique were used to guide the target lithotripsy with a hard endoscope through the sinus tract. • A drainage tube was inserted into the sinus before the operation.

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297 The residual intrahepatic stones

The right anterior segmental bile duct

Fig. 12.101  Right hepatic biliary stricture with right anterior and posterior bile ducts opening

Fig. 12.104  Preoperative direct cholangiography of the biliary tract through the biliary support tube reveals intrahepatic bile duct stones remaining

Fig. 12.102  Hard endoscopic lithotripsy Fig. 12.105  Targeted hard endoscopic lithotripsy and stone removal through the sinus duct guided by 3D visualization The hepatic vein

The dilated biliary ducts and calculus

Fig. 12.103  3D visualization shows intrahepatic bile duct stones with indwelling biliary support tube

• Such patients can be treated by ultrasound-guided staging: (a) 3D visualization technique can guide percutaneous transhepatic cathedral drainage (PTCD). The sinus tract was dilated once after 1  week, then expanding to about 16 Fr in 2 weeks; one-stage puncture, catheterization, and lithotripsy can also be performed; (b) 3D visualization technique is used to guide the target lithotripsy of choledochoscope. The patients were treated in stages

according to the individual condition of the patient (Resource 12.5) (Figs. 12.111 and 12.112).

12.10.6.5 Attention • The specific technical operation precautions for choledochoscopy (soft or hard mirror) targeting gravel and stone removal are the same as for the above-mentioned method. • The procedure is most suitable for puncture under the guidance of B-ultrasound. The best puncture point is in the anterior approach and the inferior right ribbed area of the process. Except for the right hepatolithiasis, especially near the right rib and the right posterior rib, it is not appropriate to use the lateral and posterior puncture approach. • The puncture direction of the operation requires an acute angle (parallel state) with the target bile duct and facing the hepatic hilus, which is beneficial to the operation of the choledochoscope, so that it can be carried out in a relatively smooth duct and facilitates the treatment of stones and biliary stenosis.

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Fig. 12.106  3D visualization shows the relationship between dilated bile duct and intrahepatic vessels

Fig. 12.107  3D visualization shows mild left hepatic duct stenosis, severe right hepatic duct stricture, right anterior bile duct stricture, and right posterior bile duct stricture

Severe right hepatic duct stenosis

Right hepatic duct Section of left hepatict duct

Fig. 12.108  Remove liver tissue of segments II and III, remove stones through liver cross section, and protect liver tissue of segment IV

Fig. 12.109  Plastic surgery for right hepatic duct stricture, right anterior bile duct stricture, and right posterior bile duct stricture

12  Digital Surgical Diagnosis and Management of Hepatolithiasis

Fig. 12.110  3D visualization technology guided open segmental hepatectomy combined with choledochoscopic hard targeting lithotomy for intraoperative stone removal

Fig. 12.112 Percutaneous transhepatic choledocholithotripsy guided by 3D visualization

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Fig. 12.111  Target bile ducts were subjected to percutaneous hepatic puncture under ultrasonic localization

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• In the course of fistula dilatation, it must be guided along the guidewire into the biliary tract under the supervision of X-ray fluoroscopy. • After expanding the sinus to 16 Fr or 18 Fr, the sheath tube was placed to form the fistula wall, avoiding the hepatic injury and hemorrhage in the further operation, and facilitating the entry and exit of the rigid choledochoscope.

12.10.6.6 Significance 3D visualization technology can optimize the time of establishing a surgical channel of percutaneous transhepatic cholangioscopy and lithotripsy (PTCSL), which is shorter than the previous channel establishment time: the previous PTCS lithotripsy method of sinus dilatation is 2–3  weeks, with more frequent dilatation and a greater likelihood of complications such as bleeding, biliary leakage, biliary tract infection, and peritonitis. Under the guidance of 3D visualization, the first stage lithotripsy can be performed directly through the dilated fistula of the liver, and the second stage lithotripsy can be performed by combined rigid endoscopy one week after percutaneous hepatobiliary fistula. The 3D simulation visualization surgical system was used to find the best angle of the dilated bile duct from the hepatolithiasis as the puncture point. The generally preferred puncture point was on the right margin of the xiphoid wall, and the dilated left outer bile ducts B2, B3a, and B3b were selected, or in the middle line of the right sternal clavicle, and the dilated right bile duct B7a and B6c as the puncture site. The blood vessels, intestines, and thorax were avoided, and the target bile duct was punctured. The sinus was dilated in the first stage to carry out gravel and stone removal, which guided the clinical stages I and II operation successfully. The period of stone extraction, the distance of stone extraction, and the time of operation were shortened, and the times of dilation and intraoperative bleeding were reduced, which truly achieves minimally invasive treatment of hepatolithiasis. The main difficulty of operation lies in the uncertainty of the target bile duct and the variation of the location of the bile duct and blood vessel. It is difficult to understand the lesion thoroughly by traditional examination methods. The adaptive region growing algorithm of MI-3DVS software, is applied to precisely cut the biliary tract system. After 3D reconstruction, the tree structure of the biliary tract system can be displayed as a whole, and the spatial relationship between the biliary duct and the blood vessels can be accurately displayed. It can guide the actual PTCSL operation to avoid the major vessels of the hepatic vein, portal vein, abdominal cavity, and thoracic organs, and select the precise puncture site of the bile duct, which is of great significance to improve the success rate of puncture. Applying 3D visualization technology to guide the combined use of rigid choledochoscope and protective sheath:

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the stone and its surrounding structure could be reproduced by using the 3D visualization technique, and the first, ­second, third, and even fourth-grade branches of intrahepatic bile duct that formed a complete stereoscopic “bile duct tree” could be observed; the location diagnosis of hepatolithiasis was carried out accurately; different parts and angles were selected to simulate the lithotripsy with rigid choledochoscope, and the effect of the simulated operation was observed repeatedly, according to the distribution of stones and concrete situation of bile duct dilation. An individualized surgical plan for rigid choledochoscope and sheath tube was proposed: the dilated sinus had a built-in supporting sheath, and the operation was performed in the sheath and the dilated bile duct. During the operation, the sheath tube was tightly covered in the bile duct with stones, and the sheath tube “straightened” the bile duct relative to it; forming a direct passage in vitro; the stone was flushed after crushing. Then the rigid choledochoscope was used for the “sucking” operation, and the stone flowed out quickly through the sheath tube, which improved the efficiency of stone removal. 3D visualization technique was used to guide the management of biliary stricture: The relationship between the blood vessel and bile duct must be clearly defined before plasty for biliary stricture. It was reported that the stone clearance rate, complication rate and cumulative stone recurrence of hepatolithiasis using PTCSL turned to be approximately 80.0% to 83.3%, 18%, and 32.6% to 40.0%, respectively (Jan and Chen 1995; Lee et al. 2001; Yeh et al. 1995). The main factor affecting the treatment effect was severe bile duct stenosis. In the FreeForm Modeling System virtual surgery environment, the location of bile duct stenosis and the relationship between the bile duct and its surrounding portal vein and hepatic vein can be displayed by magnifying, reducing, rotating, and transparent operation of the 3D model and its accessories. In the actual operation, the rigid choledochoscopy was applied. The bile duct dilated from the distal end of the percutaneous liver reaches the stenotic bile duct. Most of the bile duct stenosis segments are not long; mostly, membranous stenosis, and can be opened by stone forceps. If the stenosis is obvious, a biliary balloon catheter is used to dilate it first, and a series of dilators are successively delivered along the guidewire for progressive expansion. For those with a solid scar, an electric knife or laser incision can be used to dilate the scar with an airbag. After dilation, a support catheter is placed to avoid injury of bile duct blood vessels and reduce complications of biliary tract bleeding. The above treatment may significantly reduce the residual rate of stone, the final residual rate of stone, and the recurrence rate of cholangitis. In conclusion, PTCSL, based on the 3D reconstruction technique, provides a new technique for patients who cannot tolerate open surgery and postoperative residual stones.

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12.10.7  Laparoscopic Hepatectomy Combined with Choledochoscopy (Soft/Hard) for Targeted Lithotripsy and Stone Extraction Guided by 3D Visualization 12.10.7.1 Indications • No history of abdominal surgery, no or mild stenosis of the hilar bile duct, and no need for bile duct plastic surgery. • Stones diffused in the left and right intrahepatic bile ducts or localized in the left or right intrahepatic bile ducts. • Patients with hepatic area or segmental atrophy consistent with the criteria of hepatectomy and if the hospital has the facilities for laparoscopic hepatectomy or segmental resection; laparoscopic hepatectomy, or segmental combined with choledochoscopy (soft/hard) targeted lithotripsy, or stone extraction guided by 3D visualization, can be performed. 12.10.7.2 Contraindications • Patients with obvious bleeding and coagulation dysfunction. • Liver function Child-Pugh class C. • Inability to tolerate general anesthesia or pneumoperitoneum. 12.10.7.3 Surgical procedures General anesthesia with tracheal intubation. • Routine establishment of pneumoperitoneum, the establishment of puncture holes, and placement of puncture sheath. • Abdominal cavity exploration, laparoscopic cholecystectomy, and common bile duct exploration. • According to the preoperative individualized 3D visualization model of patients, the first hepatic portal is dissected, the corresponding hepatic segment/region blocked, or the Pringle technique used to temporarily block the left or right hepatic blood flow; and the damaged liver segment and the stricture segment of the intrahepatic bile duct removed as much as possible. • According to the thickness of the common bile duct, the appropriate dilator and sheath tube are selected and fixed by an assistant. The dilator is inserted through the subxiphoid puncture hole. • A water pump with adjustable pressure (0.9% sodium chloride solution) is connected with a hard mirror and reaches the target bile duct under the guidance of the 3D model.

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• Pneumatic ballistic lithotripsy: A ballistic lithotripsy device is installed under the guidance of a hard mirror. Stones larger than 10 mm are crushed by pneumatic ballistic lithotripsy. The ballistic pressure is automatically maintained within the range of 0.2–0.4  MPa by the pump. • Stone extraction through net basket: The crushed stones are repeatedly extracted by a net basket. Floating gravel is washed out through the sheath tube under the impulse of water. Bile ducts of Grade IV and above or with small bifurcation angles were removed with Cook net basket or “suction” of water flow. • Under the protection of the crushed stone casing and the rigid mirror light source, the rigid mirror can enter and exit the left and right liver smoothly, dilating the bile duct with the aid of the rigid mirror “pick,” “pull,” and “pry” forces. Under the guidance of a 3D visualization model or 3D printing model, the intrahepatic bile duct stones can be accurately located, and lithotripsy and stone extraction can be carried out. • The strictured intrahepatic duct is dilated with a soft dilator, such as a biliary balloon. For the strictured duct with a solid scar the bile duct should be opened with an electric knife first, and then a stent should be placed immediately after dilatation. Its distal end should exceed the strictured segment. • Finally, perform exploration for, and remove extrahepatic bile duct stones are, and observe the function of the Oddi sphincter. The duodenal cavity can be accessed by choledochoscope. • T-tube and drainage tubes should be retained for direct cholangiography and trans-sinusoidal treatment of calculi after operation.

12.10.7.4 Attention • The specific operation of choledochoscopy (soft/ hard) targeted lithotripsy is the same as that of the open hepatectomy or segment section combined with choledochoscope (soft/hard) targeted lithotripsy guided by 3D visualization. • If the bleeding is difficult to control or the patient cannot tolerate pneumoperitoneum during total laparoscopic hepatectomy, immediate reversion to laparotomy is necessary. • Before rigid mirror lithotripsy, a small sliver should be used to fill the lower end of the common bile duct to prevent flushing water or fine stones from entering the intestine; small gauze should be laid on the left and right omentum holes, and the suction tube should be placed for continuous suction to prevent flushing water and fine

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stones from flowing into the abdominal cavity, and postoperative abdominal cavity infection. The gauze and sliver are removed at the end of the operation. • For patients with diffuse cholelithiasis in the left and right intrahepatic bile ducts, stones can be removed by stages in order to avoid water intoxication (Resources 12.6 and 12.7) (Figs. 12.113, 12.114, and 12.115).

Fig. 12.113  The upper right image shows a 3D subabdominal biliary rigid lens through cannula into the common bile duct and intrahepatic bile duct for lithotripsy; the lower left image shows the biliary tract with biliary rigid lens for lithotripsy Fig. 12.114  Biliary rigid lens for lithotripsy under 3D laparoscopy

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12.10.8  Treatment of Hepatolithiasis Complicated with Biliary Cirrhosis Guided by 3D Visualization In patients with hepatolithiasis, chronic recurrent cholangitis and mechanical obstruction resulted in thickening of the fibrous tissue, infiltration of inflammatory cells, and formation of fibrous separation in the portal vein. The new liver tissue nodules compress the hepatic venous branch, which causes the portal vein to shrink, becoming irregular, and thickened. It reduces portal venous blood flow, leading to liver atrophy and portal hypertension. At the same time, the complicated hepatolithiasis causes atrophy of the liver lobe or segment of the liver; resulting in the displacement of the hepatic portal and the distortion of the portal vein, which affects the portal venous blood flow. Extensive stenosis, infection, and cholestasis of hepatobiliary duct cause hepatocytes to be damaged and regenerate, which easily leads to biliary cirrhosis and portal hypertension. These progressive pathological changes worsen over time. With early detection, pathological changes of the liver can be halted if the obstruction and stones are removed. Is the choice of surgical methods for this type of patient first to resolve portal hypertension, or to treat biliary obstruction? Is it a simultaneous operation or a staged surgical treatment? Is it an open surgery, a liver transplant, or a minimally invasive treatment? Scholars have their own opinions. At present, hepatolithiasis complicated with biliary cirrhosis

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bile duct display

T-tube

a

bile duct display

T-tube

b Fig. 12.115  No calculi observed on postoperative direct cholangiography. (a) 2013-12-11; (b) 2014-01-22

often need multiple surgical methods, but the operation is difficult and risky. Therefore, individualized design of the surgical scheme for cholelithiasis should be carried out according to the preoperative Child-Pugh classification of liver function, the experience of the operator, equipment condition, and 3D visualization results. Thus, choose one or more of the above surgical methods or liver transplantation for treatment.

12.10.8.1 Preoperative Evaluation 3D visualization is used to evaluate the changes of the portal vein system and collateral circulation, the distribution of stones in the hepatobiliary duct, the degree and extent of bile duct stricture, the pathological features of the liver, and the reserve liver function. It has important value in determining the choice of treatment, operative method, and operative approach. This is the unique advantage of 3D visualization. 12.10.8.2 Preoperative Preparation • Liver function reserve A grade. • Acquisition of high-quality CT image data, especially in the portal vein phase. • 3D visualization evaluation.

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12.10.8.3 Contraindications • Obvious bleeding and coagulation dysfunction. • Liver function Child-Pugh class C. • Inability to tolerate general anesthesia. 12.10.8.4 Operation Methods In the case of patients with a bile duct drainage tube or support tube, the target lithotripsy through sinus choledochoscope (soft or hard endoscope) guided by 3D visualization should be adopted. For those without a bile duct drainage tube or support tube, open hepatectomy or segmentectomy combined with choledochoscopy (soft/hard mirror) targeted lithotripsy and stone removal guided by 3D visualization should be adopted. • If the surgical approach is severely impeded due to history of multiple biliary tract operations, portal hypertension, severe hepatic adhesions, and extensive portal vein branch expansion, it is necessary to fully understand the operation method of the previous one to avoid the dilated portal vein branch and carefully search for the bile duct along the right liver surface. Once the bile duct is confirmed, the operation is assured of success. • Prevent bleeding from varicose veins on the surface of the bile duct wall and intima due to the thickening of the bile duct wall. • Choledochoscopy (soft/hard): If suppurative bile is found, stones blocking the hilar of the liver are removed as much as possible, and T-tube is placed. After antimicrobial chemotherapy, targeted lithotripsy through sinus choledochoscope (soft or hard) guided by a 3D visualization technique is selected. • Select the appropriate and sheath, according to the thickness of the bile duct. Dilator-specific methods are the same as that for the targeted lithotripsy through sinus choledochoscope guided by 3D visualization. • Finally, the extrahepatic bile duct stones are located and removed, the distal bile duct is observed to be unobstructed and the Oddi sphincter normal. T-tubes and drainage tubes are indwelled.

12.10.8.5 Attention • This case is exceptional. Biliary cirrhosis usually occurs after multiple biliary surgeries, which requires a combination of various surgical methods. Moreover, it is necessary to design an individualized surgical program for biliary calculi because the operation is difficult and hazardous.

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• Most importantly, bleeding, even massive hemorrhage may occur due to inflammation, hyperemia, edema, erosion, blood leakage, and vascular varices of the bile duct. Therefore, the hard mirror cannula should be guided by the light source of the hard choledochoscope throughout the process to prevent the blind entry of punctured variceal vessels. The hard mirror must be placed in the midFig. 12.116  3D visualization shows hepatic atrophy and hypertrophy; digital type: LII - VII, Sundefined, DII-VII, C

dle of stone in the field of view during lithotripsy to prevent sharp lens oblique surface injury or puncture of blood vessels, bile duct, bleeding and bile leakage, and avoid the metal mesh head stimulating the erosive bile duct intima (Resources 12.8, 12.9, and 12.10) (Figs.  12.116, 12.117, 12.118, 12.119, 12.120, 12.121, 12.122, 12.123, 12.124).

The dilated biliary ducts and calculus

The liver

Fig. 12.117  3D visualization shows strange forms of the intrahepatic vessels and bile ducts, and the bile ducts are filled with stones

The liver The portal vein system

dilated biliary ducts and calculus The spleen The hepatic artery

The pancreas

Fig. 12.118  3D visualization shows the dilated and tortuous portal vein system The biliary ducts and calculus

The portal vein system

12  Digital Surgical Diagnosis and Management of Hepatolithiasis Fig. 12.119  3D visualization shows liver atrophy and hypertrophy, with strange forms of intrahepatic vessels and bile ducts, and bile ducts filled with stones

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Hepatic vein The spleen Portal vein

The hepatic artery The pancreas

Dilated bile duct The kidney

Fig. 12.120  3D visualization shows the dilated and tortuous portal vein system

Fig. 12.121  3D visualization shows the relationship between the hepatic artery and bile duct

Dilated portal vein

The bile duct

The hepatic artery

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12.10.9  Complication Prevention and Management of Targeted Lithotripsy for Hepatolithiasis with 3D Visualization Assisted by 3D Laparoscopy and Choledochoscopy 3D visualization can be used to evaluate the lesions of bile duct and stones in all directions and from different angles; and assist in intraoperative navigation to reduce the blindness of intraoperative exploration; 3D laparoscopy is clear, stereoscopic, and effective; the hard lens of the choledochoscope has magnification effect, clear field of ­ vision and large operating cavity, and when it is combined with the individualized 3D reconstruction model, the location of stones can be quickly identified and the operation time can be shortened. The combination of these three technologies can remove stones quickly, accurately, safely, and thoroughly. Nonetheless, a certain risk of complications in this procedure still exists due to the complexity of hepatolithiasis and the characteristics of various diseases, especially in the early stages of this technique.

Fig. 12.122  Ballistic lithotripsy

12.10.9.1 Biliary Injury

Fig. 12.123  Calculus taken out of the intrahepatic bile duct

intrahepatic bile duct

Fig. 12.124  No residual calculi were found by direct postoperative cholangiography

Causes Most injuries are caused by a blind and violent rigid mirror exploration or lithotripsy. In less severe cases, local damage of bile duct mucosa is caused, while in severe cases penetrating injury of the bile duct results, even combined with an injury of adjacent organs. Especially, the diseased bile duct is located in segment VII of the liver, adjacent to the diaphragm, and there is long-term inflammatory stimulation resulting in adhesion between the liver and the diaphragm. Or if during the operation, the lithotripsy rod accidentally pierced the bile duct and reached the liver capsule and diaphragm, which formed the communication among the bile duct, diaphragm, and thoracic cavity. Preventive Measures • When it is difficult to find the branch of the intrahepatic grade II bile duct during the operation, we can combine 3D visual targeting to locate the bile duct and stones, so as to avoid blind exploration. • The operation path of bile duct communicating with the outside, should be established by using the middle diameter sheath tube, in order to ensure the operation of the choledochoscope in the sheath tube. • For patients without choledocholithiasis, choledocholithotomy should be performed at a high level to avoid bile duct laceration during choledochoscopy.

12  Digital Surgical Diagnosis and Management of Hepatolithiasis

• The risk of stone extraction for grade III and above bile ducts should be evaluated according to the intraoperative conditions, such as the angle of the bile duct, the actual diameter of the bile duct, and the size and location of the stones, especially for the distal bile duct near the diaphragm, which is difficult to find after injury, and easily involved in the diaphragm and thoracic cavity. • Attention should be paid to the following details during operation: The lithotripsy rod can be activated only when it touches the stone; lithotripsy rod should be placed in the center of the stone, not between the stone fissure or the wall of the bile duct; hit step by step when the stone is large; the size of the gravel should be determined by the ability to be removed by the net basket or flushed out of the bile duct; when the net basket with stones cannot be pulled out, release it and further gravel should be carried out. Forced pull should be forbidden. No special treatment is required for the damage of the bile duct mucosa. After biliary tract damage, it can repair itself. Once the diagnosis of biliary tract fistula is clear, it should be drained in time to control infection. Surgical treatment should be performed when conservative treatment is ineffective.

12.10.9.2 Biliary Bleeding The occurrence of biliary bleeding is often directly related to the basic state of the biliary tract, often complicated with recurrent biliary tract infection, leading to congested wall, edema, and fragile texture. Patients with liver cirrhosis have extensive varices of the bile duct wall, which is also an important risk factor of biliary bleeding. Several treatment methods are introduced below in terms of the prevention and treatment of biliary bleeding: the punctate hemorrhage of the bile duct wall can be washed with norepinephrine solution or thrombin solution, inducing a satisfactory hemostatic effect. However, the effect of intraoperative hemostatic drug washing for extensive bleeding of bile duct mucous membrane is unsatisfactory, and will often require gauze packing, balloon compression, or electrocoagulation under choledochoscope so as to prevent the recurrence of bleeding after surgery. The diagnosis of biliary bleeding is not difficult for patients with an indwelling T-tube. However, the key is to determine the cause and location of bleeding. Selective celiac arteriography can be used as the first choice for the diagnosis and treatment of postoperative biliary bleeding. When nonoperative treatment is ineffective, timely surgical hemostasis should be performed. With regard to the prevention of biliary hemorrhage, first of all, preoperative active control of biliary tract infection and the improvement of liver function should be ensured, and especially in patients with cirrhosis, the operation should be performed on the premise of Child-Pugh class A or B grade of liver function; secondly, the operation should

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be performed gently in order to reduce the chance of vascular injury; in addition, T-tube should be placed at the appropriate time, and the stones should be removed by stages through the sinus tract if the bile duct was found to be suppurative or at high risk of biliary bleeding during the operation.

12.10.9.3 Gastrointestinal Water Retention Reasons For patients with difficult stone removal or extensive stone distribution, saline should be continuously infused during the operation to keep the visual field clear. A large amount of physiological saline flows into the gastrointestinal tract through the common bile duct, resulting in water retention in the gastrointestinal tract, and secondary water–electrolyte balance disorder, and even water poisoning. Prevention and Treatment Before the removal of hepatolithiasis, the lower part of the common bile duct should be temporarily filled with a gauze strip to reduce the amount of flushing fluid entering the intestinal tract through it. Meanwhile, the suction device is used to continuously draw the overflowing lavage fluid to reduce the water adsorption; the amount of biliary flushing must be controlled, and the stone extraction should be completed as soon as possible.

12.10.9.4 Biliary Leakage The occurrence of bile leakage is closely related to the laparoscopic suturing technique of the surgeon, especially when the bile duct wall is thin; on the other hand, because the intrahepatic dilatation bile duct is adjacent to the liver surface, bile leakage or bile duct drainage may occur when the bile duct is broken during the process of hard mirror lithotripsy and net basketing. The prevention of bile leakage first requires the surgeon to master the laparoscopic suture technique. After suturing, the bile leakage around the T-tube should be carefully observed. Secondly, the 3D visualization technique can be used intraoperatively to confirm the individualized blood supply of bile duct, so as to avoid cutting the main blood supply artery of the extrahepatic bile duct when cutting the common bile duct; then master the techniques of hard mirror lithotripsy and net basket stone removal. In conclusion, 3D visualization-assisted 3D laparoscopy, and choledochoscope hepatolithiasis targeting lithotripsy is a novel operative method, which provides a new choice for the diagnosis and treatment of hepatolithiasis. For hepatobiliary surgeons, mastering the principles of prevention and management of the complications mentioned above is of great practical value for the rational application of the procedure.

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12.11 Application of 3D Visualization in Reoperation of Bile Duct 12.11.1  Reoperation of Bile Duct Reoperation of the bile duct, as one of the most difficult problems in biliary surgery at present, refers to the operation that needs to be performed again after biliary surgery because the primary disease has not been cured or postoperative complications have occurred. The causes of the reoperation of the biliary tract are complicated. On the one hand, the failure to completely remove the factors of biliary tract primary diseases is the main reason; on the other hand, reasons such as inappropriate surgical methods, complications after biliary tract surgery, and iatrogenic biliary tract injury can also cause reoperation of the bile duct. A good therapeutic effect can only be achieved by a more accurate preoperative evaluation and a reasonable surgical plan.

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without hepatectomy, (d) stricture relief without cholangioplasty or resection of lesions, (e) unobstructed drainage without proper choledochojejunostomy. Other reasons for reoperation of bile duct include the following: incomplete resection of choledochal cyst, with only choledochojejunostomy, partial hepatectomy not performed in Caroli’s disease, recurrence of stones or biliary cancers caused by stenosis of the lower common bile duct or by loss of Oddi sphincter function without choledochojejunostomy. Postoperative Complications of Biliary Tract Various complications after biliary tract surgery may occur due to the previously missed diagnosis or unreasonable choice of surgical methods, such as biliary bleeding, drainage tube shedding, bile leakage, stricture of choledochojejunostomy, constrictive papillitis, and Oddi sphincter fibrosis. The complications mentioned above need to be reoperated because of the insufficiency of clinical diagnosis and surgical methods during the first operation.

12.11.1.1 Reasons

Iatrogenic Biliary Tract Injury It refers to biliary tract injury caused by improper operation Main Reasons The disease itself and the operation. The disease itself mainly of the surgeon. The causes of iatrogenic biliary tract injury refers to the recurrence or residual of stone, benign non-­ are related to various factors. According to the causes of calculous biliary stricture, cystic dilatation of bile duct, and injury, the location, degree, and type of biliary tract injury, as biliary tract tumor; the main reasons for reoperation include well as the systemic and local complications of patients, the missed diagnosis before and during operation, recurrence of principle of injury control should be followed, and the approdiseases caused by the improper choice of operation timing priate surgical plan selected. and operation mode, reoperation for various postoperative Other Reasons complications, and iatrogenic bile duct injury. Biliary bleeding, residual cystic duct stones, stricture of the biliary tract after liver transplantation, biliary tract infection Residual and Recurrence of Biliary Stones The incidence of residual stones or recurrence after surgical or recurrence of stones caused by stricture of choledochojeclearance was 29.6%, and that of reoperation was 18.7 (Jan junostomy, unexpected detection of biliary tract tumors or et al. 1996). The factors related to recurrence include incom- secondary biliary tract tumors (such as long-term canceraplete stone removal in the first session, biliary stricture, loss tion of postoperative intrahepatic cholelithiasis) after the first of Oddi sphincter function, cholestasis, and bacterial biliary tract operation. infection. Improper Choice of Surgical Timing and Procedures Patients with biliary tract infection are advised to undergo a definitive surgery after antibiotic chemotherapy. However, if there is no obvious remission after 2 days of active treatment in the acute phase, surgical treatment should be performed to solve the biliary obstruction and establish biliary drainage. Postoperative complications and mortality are high because the emergency operation can hardly solve complicated biliary diseases, such as acute suppurative cholangitis. Secondary or multiple biliary tract operations are necessary when (a) the principle of “relieving the obstruction, removing lesions and building unobstructed drainage” is not followed, (b) only part of the stone is removed, (c) atrophic liver or lesions

12.11.1.2 Preoperative Preparation and Evaluation Sufficient preoperative preparation and accurate preoperative evaluation are the guarantees for successful biliary surgery since the reoperation of the bile duct is complicated and difficult. Special attention should be paid to the following aspects: • The acquisition of detailed medical history and previous surgical data, including the specific surgical procedure for each operation, the location and time of the drainage tube placement, and the postoperative recovery of the patient. • Selection of a well-reasoned examination plan and comprehensive analysis: observe the spatial anatomical rela-

12  Digital Surgical Diagnosis and Management of Hepatolithiasis

tionship between the biliary system and its surrounding blood vessels to clarify the location of the lesion through combining more than two imaging examination methods, especially the application of 3D visualization. Determine whether there was stricture or dilatation of intrahepatic and extrahepatic bile ducts; whether they were complicated with stones or carcinogenesis; and evaluate the general condition of the patients and the severity of the local lesions of the biliary tract. • Reasonable preoperative treatment: Understand the general condition of the patient according to the preoperative examination, mainly including coagulation mechanism, and liver and kidney function, supplemented with necessary preoperative adjuvant therapy to improve the preoperative systemic condition of patients and improve surgical tolerance. When complicated with biliary tract infection, antibiotic regimens are used to control acute biliary tract infection. • Selection of appropriate time and method of operation: The goal of reoperation of the biliary tract is the definitive surgery, which strives to remove the factors of disease recurrence, reduce complications, and obtain a good clinical effect. Therefore, according to the patients’ general condition, liver function and the anatomic changes of the biliary tract after biliary tract operation, the proper timing, and method of operation should be chosen on the basis of detailed preoperative diagnosis and full evaluation, in order to ensure the postoperative effect of reoperation of the bile duct.

12.11.1.3 Surgical Procedures Since the local anatomy of the surgical site and pathology has changed in the reoperation, the difficulty and the rate of complications are higher than that of the previous operation. Thus, more detailed preoperative evaluation and preparation are needed to determine a reasonable individualized operation plan according to the patients’ individual condition, preoperative imaging examination, and intraoperative exploration. Choledocholithotomy and T-tube Drainage This method is suitable for the patients with recurrent stones of the common bile duct or common hepatic duct, or grade 2 cholangiolithiasis of the intrahepatic bile duct, without bile duct stenosis, and without stenosis at the lower end of the common bile duct. In combination with intraoperative choledochoscopy, try to remove stones at one time while preserving the function of Oddi sphincter as far as possible. Avoid misuse of the biliary anastomosis.

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Roux-en-Y Choledochojejunostomy It includes side-to-side Roux-en-Y choledochojejunostomy and Roux-en-Y hepaticojejunostomy after common bile duct transection, and the common bile duct duodenal anastomosis should be abandoned. It is suitable for common bile duct dilatation with stricture of the lower end of the common bile duct or Oddi sphincter dilatation with intestinal fluid reflux. The common bile duct should be transected and closed after removing the distal stones. If there is a stricture of left and right hepatic duct, or grade 2 hepatic duct, it is better to have strictured hepatic duct plasty, high bile duct, or hilar bile duct pelvic cholangiojejunostomy. Hepatectomy For intrahepatic bile duct stones complicated with hepatic atrophy and hypertrophy, or with cholangiocarcinoma, hepatectomy should be performed, and the curative effect of regular hepatectomy is better than that of irregular hepatectomy. For bilateral multiple bile duct stones, preoperative liver function and volume should be assessed, and bilateral hepatectomy should be performed in one stage or multiple stages. For the patients whose hepatolithiasis is difficult to remove by one operation, the cecal end of the ascending jejunum can be retained subcutaneously for choledochoscopic lithotripsy, or percutaneous transhepatic cholangiocentesis (PTCS), once or multiple choledochoscopic lithotripsies (hard or soft) to reduce the trauma of laparotomy and maximize the removal of residual stones. Laparoscopy Combined with Hard or Soft Choledochoscopy for Intrahepatic Bile Duct Lithotripsy If the patients with recurrence of hepatolithiasis have laparoscopic exploration, separable adhesion, and exposure of the first hepatic hilum, the common bile duct can be incised under laparoscopy. Through the common bile duct approach, a soft or hard choledochoscope can be adopted for lithotripsy of the common bile duct and intrahepatic bile duct stones; if one-time stone removal is impossible, T-tube can be indwelled for postoperative T-tube drainage through the sinus tract. Laparoscopic hepatectomy or laparoscopic-­ assisted hepatectomy can be used if intrahepatic hepatolithiasis complicated with canceration are found. Intrahepatic Lithotripsy Through Sinus Tract or PTCS For patients with T-tube or intrahepatic bile duct support tube that was previously indwelled, lithotripsy can be performed under hard and soft choledochoscopy through the sinus tract that formed 1–2 months after surgery; while for patients with multiple hepatolithiasis complicated with bili-

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ary cirrhosis or Child-Pugh class B liver function, primary or secondary PTCS, intrahepatic bile duct lithotripsy can be performed to reduce surgical trauma. Severe Symptomatic Patients Liver transplantation is feasible for patients with extensive intrahepatic bile duct stones whose symptoms occur repeatedly and lead to biliary cirrhosis and severe damage to liver function.

12.11.2  Application of 3D Visualization Technique in Reoperation of the Bile Duct With the development of digital medicine, medical image processing technology based on 3D visualization has been widely used in the diagnosis and adjuvant treatment of clinical diseases. 3D visualization technology can reproduce the anatomical space structure between abdominal organs, accurately locate the lesion position, assist in formulating the operation plan, and guiding the operation in real time so as to reduce the risk of operation and postoperative complications effectively. For patients with residual or recurrent biliary calculi, a 3D visualization technique is used to evaluate the anatomy and variation of stones and intrahepatic duct and hepatic parenchyma lesion accurately, a reasonable and effective hepatectomy program can be formulated through simulation surgery. The anatomy of the bile duct, portal vein, and hepatic vein can be accurately and intuitively displayed through a 3D visualization technique. It is of great significance for the patients undergoing reoperation of the bile duct. • The overall anatomy of upper abdomen: The spatial anatomical relationship between the liver and extrahepatic bile duct system and its adjacent abdominal organs is observed stereoscopically, and the extent of lesions and the degree of surgical difficulty evaluated from the aspect of gross anatomy. • Anatomical observation of liver and biliary system: Stereoscopic observation of liver deformation, atrophy, or hypertrophy of liver segments/lobes, and transposition of portal hepatis; the number and extent of hepatic segments affected by biliary tract diseases; the variation of the intrahepatic bile duct system, hepatic artery, hepatic vein

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and portal vein, and the anatomical changes to the above-­ mentioned duct system caused by previous operations. • Anatomical changes of the biliary system: Location of the diseased hepatic segment, location, size, shape, and quantity of gallstone or tumor lesion, and length and degree of stricture or dilatation of bile duct. 3D visualization technology provides individual 3D liver vascular anatomy, which is helpful for accurate location diagnosis of stones, tumors, the anatomical variation of intrahepatic ducts, and hepatic parenchyma lesions. According to the anatomical features of the 3D visualized biliary tract, combined with the patient’s whole body and liver function, a plan for individualized reoperation of the bile duct was formulated. Specific treatment methods are detailed in Sect. 12.10.

References Biliary Surgery Branch of Chinese Medical Association. Guidelines for the diagnosis and treatment of hepatolithiasis. Chin J Dig Surg. 2007;6(2):156–61. Couinaud C.  Lobes et segments hépatiques: notes sur l'architecture anatomiques et chirurgicale du foie. Presse Med. 1954;62:709–12. Dong J-H, Feng X-B, Duan W-D. Stepping into the “segmental” era of biliary surgery. Chin J Digest Surg. 2017;16(4):341–4. Fang CH, Liu J, Fan YF, et al. Outcomes of hepatectomy for hepatolithiasis based on 3-dimensional reconstruction technique. J Am Coll Surg. 2013;217(2):280–8. Huang CC.  Partial resection of the liver in treatment of intrahepatic stones. Chin Med J. 1959;79:40–5. Huang Z.  The collection of academicians Huang Zhiqiang. Beijing: People’s Military Medical Press; 2014. p. 50–76. Jan YY, Chen MF.  Percutaneous trans-hepatic cholangioscopic lithotomy for hepatolithiasis: long-term results. Gastrointest Endosc. 1995;42(1):1–5. https://doi.org/10.1016/ s0016-­5107(95)70234-­2. Jan YY, Chen MF, Wang CS, Jeng LB, Hwang TL, Chen SC. Surgical treatment of hepatolithiasis: Long-term results. Surgery 1996;120:509–14. Lee SK, Seo DW, Myung SJ, Park ET, Lim BC, Kim HJ, Yoo KS, Park HJ, Joo YH, Kim MH, Min YI.  Percutaneous transhepatic cholangioscopic treatment for hepatolithiasis: an evaluation of long-term results and risk factors for recurrence. Gastrointest Endosc. 2001;53(3):318–23. https://doi.org/10.1016/ s0016-­5107(01)70405-­1. Sakpal SV, Babel N, Chamberlain R. Surgical management of hepatolithiasis. HPB (Oxford). 2009;11(3):194–202. Yeh YH, Huang MH, Yang JC, Mo LR, Lin J, Yueh SK. Percutaneous trans-hepatic cholangioscopy and lithotripsy in the treatment of intrahepatic stones: a study with 5-year follow-up. Gastrointest Endosc. 1995;42(1):13–8. https://doi.org/10.1016/s0016-­5107(95)70236-­9.

Digital Surgical Diagnosis and Management of Biliary Dilatation

13

Jian Yang, Haoyu Hu, and Chihua Fang

13.1 Introduction Biliary dilatation (BD), also known as bile duct cyst, is a rare primary biliary disease. It can be congenital, and can also occur in adulthood, mainly manifesting as intrahepatic and extrahepatic bile duct single or multiple local dilatations. The typical clinical manifestations include jaundice, abdominal pain, and abdominal mass, often accompanied by pancreatitis, cholangitis, and carcinogenesis. The canceration rate is 20 to 30 times that of the general population. Secondary biliary dilatation caused by stones, strictures, or tumors of the bile duct does not belong to the category of BD.

13.2 E  tiology and Clinical Classification of Biliary Dilatation 13.2.1 Etiology of BD BD is predominant in infants and young children, with a male-to-female ratio of 1: (3–4) (Bhavsar et  al. 2012; Soares et  al. 2014), mainly in Southeast Asia and Japan. The incidence of BD is remarkably higher in Eastern countries, notably Japan and Koreas, with a reported incidence of 1 in 1000, whereas it is 1:100,000–150,000 in Western countries (Lee et al. 2009a, b). There have been three theories about the etiology of this disease: (a) the theory of abnormal proliferation of bile duct epithelium, (b) the theory of abnormal pancreaticobiliary duct confluence, and (c) the theory of abnormal nerve development. After Babbit et  al. proposed in 1969 that abnormal pancreaticobiliary junction was the leading cause of choledochal cysts (Babbitt

J. Yang · H. Hu · C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China

et al. 1973), many researchers began to support this theory. Abnormal pancreaticobiliary duct confluence is a congenital developmental abnormality, in which the pancreaticobiliary duct flows far from the intestinal wall outside the sphincter of the duodenal papilla. According to the different parts of the confluence, it can be divided into (a) mucosal or submucosal confluence; (b) external confluence of the intrinsic muscular layer. In the latter case, the pancreaticobiliary ducts confluence in the pancreatic parenchyma outside the proper muscular layer of the duodenum, and then form a common duct opening to the Vater papilla, which is the theory of abnormal pancreaticobiliary duct confluence. The anatomical basis of this theory is the confluence of the pancreaticobiliary duct outside the sphincter, the confluent tube is long, and the junction is obtuse. When the distal ampullary sphincter acts, the two tubes can communicate freely, and the pancreatic juice is often countercurrent to the bile duct because of high pressure in the pancreatic duct. The pathological changes of biliary tract caused by pancreatic juice flow into the bile duct were related to the degree of the activation of pancreatic enzyme: (a) there were no pathological changes in the biliary tract if the pancreatic enzyme was not activated; (b) mild or slow activation of the pancreatic enzyme caused hyperplasia of the mucous membrane of the bile duct, metaplasia of the mucosa, and chronic bacterial infection. Mucosal epithelial metaplasia easily leads to complications such as cholecystitis, biliary calculi, and gallbladder cancer carcinoma; (c) intense activation of the pancreatic enzyme leads to pathological changes such as the exfoliation of the mucous membrane, rupture of elastic fiber in the muscle layer, stricture of the end of the bile duct, and acute bacterial infection. The laceration of elastic fibers in the muscular layer of the bile duct is more likely to cause complications such as perforation of the bile duct and dilatation of the common bile duct. Bile flow into the pancreatic duct mainly causes acute pancreatitis or acute necrotizing pancreatitis.

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13.2.2 Clinical Classification of Biliary Dilatation There are many BD classification methods, which can be divided into intrahepatic type, extrahepatic type, and mixed type, according to the location of occurrence. Todani classification (Miyano et al. 2000) (Fig. 13.1) and Dong’s classification is commonly used clinically. Todani Classification Type I Dilatation of the extrahepatic bile duct. Type Ia Cystic dilatation of the common bile duct. Type Ib Saccular dilatation of the common bile duct. Type Ic Fusiform dilatation extending to the common bile duct. Type II Diverticulum of the common bile duct. Type III Choledochocele involving intraduodenal portion of CBD. Type IV Intra- and extrahepatic duct dilatation. Type IVa Both intra- and extrahepatic cysts. Type IVb Multiple extrahepatic cysts only. Type V Intrahepatic cysts only (Caroli disease) (Fig. 13.2). Jiahong Dong et al. proposed a new classification method based on the cyst location and pathological features in the biliary tree, referred to as Dong’s classification (Dong et al. 2013). Dong’s Classification Type A Cystic dilatation of the peripheral biliary tree limited to the intrahepatic bile ducts. Type A1 Cystic dilatation of the bile duct was limited to one hepatic lobe or several segments.

IA

III

IB

IV A

Type A2 Cystic dilatation of the bile duct was diffused to the entire intrahepatic biliary tree. Type B Cystic dilation of central large intrahepatic bile duct above the hilar convergence. Type B1 Single localized form limited to one hepatic lobe. Type B2 Cystic dilation in hilar convergence or in bi-lobar central bile ducts. Type C Cystic dilatation of the extrahepatic bile duct. Type C1 Without intrapancreatic bile duct involvement. Type C2 With intrapancreatic bile duct involvement. Type D Cystic dilation involving both the intra- and the extrahepatic bile ducts. Type D1 Cystic dilation limited to one lobe. Type D2 Cystic dilation expanded to bi-lobar bile ducts. Type E Cystic dilation of the distal common bile duct.

13.3 I maging Diagnosis of Biliary Dilatation The imaging diagnosis is helpful in determining the extent of involvement and the degree of dilation of the diseased bile duct, as well as the structure of the biliary and pancreatic duct, which can provide a basis for the evaluation of patient’s condition, formulation of the treatment plan and selection of the surgical procedure.

13.3.1 Ultrasonography Ultrasonography (US) is noninvasive and accurate, with specificity as high as 97%, by which the adjacent liver and

IC

II

IV B

V

Fig. 13.1  Diagram of Todani classification of BD (provided by Yan Jiayan, Renji Hospital, Shanghai Jiao Tong University)

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Fig. 13.2  Imaging of BD

pancreas can be displayed; from which the degree and range of the dilatation of the intrahepatic and extrahepatic bile ducts can be determined. US has become the currently preferred imaging method. Todani classification: type II biliary cysts and Caroli’s disease are apparent by ultrasound imaging. The typical US show “cysts” in the common bile duct, most of which are spherical, oval, or fusiform, and can extend to the hilar of the liver or the head of the pancreas, presenting with a clearly bounded cystic anechoic area. This area is connected to the common bile duct, associated with no or slight dilatation of the proximal bile duct. The cyst is distributed along the main branch of the bile duct and merged with the hepatic portal. The cyst presents a round or fusiform non-echoic area; those which present as “lotus root ganglion” located in the ventral side of the portal vein and the intrahepatic bile duct with bead dilatation are the manifestation of Caroli’s disease. When complicated with calculi, strong echoic masses are seen in the anechoic area of the bile duct, accompanied by an acoustic shadow, and the position of the bile duct can be moved. When malignant change occurs in the choledochal cyst, it can be seen that the cyst protrudes from the cystic wall to the cystic lumen, presenting an irregular hyperechoic mass or local thickening of the cystic wall. Real-time dynamic observation of the changes of the bile duct wall is of great value for early detection of carcinogenesis. Choledochal cyst and extrahepatic cystadenoma

can be differentiated by ultrasound without intracavitary separation. Despite the advantages of ultrasonography mentioned above, US can neither display the entire appearance of the intrahepatic and extrahepatic bile ducts and the main pancreatic duct, nor distinguish the tissue structure around the bile duct and the area of confluence of the pancreatic duct and the bile duct. The reason is that US is susceptible to intra-­ abdominal intestinal gas interference and the limits of the orientation of an ultrasound section. The accuracy of ultrasonography cannot adequately meet the needs of clinical diagnosis, so it is of limited help in the development of surgical plans. Endoscopic ultrasonography (EUS) is a combination of ultrasonography and endoscopy. It can acquire histological features of the pipeline and ultrasound images of adjacent organs. EUS can directly scan the hepatic hilus and the lower part of the common bile duct through the duodenal bulb and descending part; and can display the pancreaticobiliary junction and the diseased bile duct.

13.3.2 Multi-Slice CT With the clinical popularization of submillimeter CT, Multi-­ Slice Computer Tomography (MSCT) has significantly

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improved in terms of spatial and temporal resolution. Through MRCT, the size, shape, and extent of cysts can be displayed clearly; also, the relationship between the cysts and their surrounding structures, as well as the complications and signs conducive to the diagnosis of this disease can be well displayed. For example, “central dot” sign: small dotted soft tissue shadow in cystic shadow, whose density is lower or equal to that of liver parenchyma on the plain scan. This “central dot” is the imaging of the intrahepatic portal vein branch, which was previously considered to be a specific sign for the diagnosis of Caroli’s disease; however, some scholars believe that this sign can also be seen in the dilated bile duct after obstruction. Therefore, the diagnosis should be combined with other comprehensive analyses. The “beading sign,” or “tadpole sign”: intrahepatic biliary cysts appear as multiple circular water-like density lesions, with mildly dilated bile ducts and saccular lesions intermingling with each other or on their margins. This disproportionate dilation and its characteristics with normal bile ducts are the keys to differentiate biliary cysts from obstructive biliary dilatation, which is manifested as a gradual thinning ratio from the center to the periphery. The “beading sign,” or “tadpole sign” is valuable in the diagnosis of Caroli’s disease (Park et  al. 2005). Contrast-enhanced CT examination showed that the tumor nodule in the bile duct wall protruded into the lumen is significantly enhanced, which is the basis for the diagnosis of BD canceration (Fig. 13.3). Intravenous injection of cholestyramine for enhanced contrast spiral CT cholangiography (IVC-SCT) is useful in determining the relationship between cysts and bile ducts. Meanwhile, the three-dimensional images of the biliary tract and its surrounding anatomical structure can be obtained by image post-processing, which provides valu-

Fig. 13.3  Contrast-enhanced CT scan showing an enhanced nodular shadow about 2 cm in diameter on the wall of the choledochal cyst, suggesting the carcinogenesis of the cyst (arrow)

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able information for the selection of treatment schemes. If there is a communication between the cyst and the bile duct, the resolution of CT is sufficient to show the accumulation of contrast media in the cyst, thus making a definite diagnosis of the choledochal cyst. However, the display of cholangiography needs a contrast agent to be discharged into the bile duct. The results of the MSCT can be affected when BD is complicated with obstructive jaundice and cholangitis. Stockberger et al. (Yu et al. 2004) found that the development rate of the bile duct was only 25% when the level of serum bilirubin was higher than 34 μmol/L; while the development rate of the bile duct was 93% when the level was less than 34 μmol/L. At the same time, the incapability of CT to clearly display the detailed characteristics of the distal common bile duct and pancreaticobiliary duct confluence brought certain difficulties to the formulation of the operation plan. Although CT has the advantages of a high diagnosis rate, moderate cost, and minimal invasiveness, an allergic reaction may occur because of the need for intravenous injection of contrast agent. Also, the patient is instructed to hold his breath during the examination, which is often impossible for children under the age of 5 years, especially for infants, and artifacts are prone to be produced, thus reducing the efficacy of the examination.

13.3.3 ERCP and PTC As diagnostic and therapeutic methods for the final diagnosis of BD, ERCP, and PTC can be used to classify BD accurately, so that the structure of the biliary and pancreatic duct, and the shape and extent of the cyst can be clearly displayed. They can also be used to judge the presence of cholangiopancreatic stones, strictures, and carcinogenesis, as well as to determine the distal bile duct and Todani classification: the anatomical relationship between extrahepatic part and the pancreatic duct of type I biliary cyst and type IVa cyst confirmed the existence of abnormal pancreaticobiliary junction. It is critical to determine the anatomical location of the confluence of the cholangiopancreatic duct because this plays a crucial role in the avoidance of injury to the pancreatic duct during the excision of the cyst to facilitate the discovery of stones in the common bile duct or confluence, and to remove distal tumors. ERCP is most suitable for adult patients without cholangio-­intestinal anastomosis. It can highlight the confluence of the pancreatic duct and the bile duct through the ampulla and can also be used to determine whether there is cancer by biopsy or cytological examination of the cells (Fig.  13.4). The symptom of severe cholangitis can be relieved either by the removal of stones in the cyst through the incision of the duodenal papilla, or by the placement of

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Fig. 13.5  PTC diagnosed a case of type IV BD, but showed poor results in the lower end of the common bile duct and at the confluence of the biliary and pancreatic ducts

Fig. 13.4  ERCP clearly showing the shape and extent of intrahepatic and extrahepatic bile ducts and cysts, and suggesting that the patient has an abnormal confluence of the pancreatic bile ducts

temporary endoscopic stents before the operation. In patients with portal hypertension, the esophagus and stomach fundus can be examined by endoscopy. All branches and cavities of the bile duct should be examined during ERCP, and cystic wall biopsies should be performed, if necessary, to exclude the possibility of malignancy. The use of balloon blockage ensures that the bile duct tree is adequately filled with contrast media, especially for patients who have previously undergone cyst-duodenostomy. ERCP is the first choice for the diagnosis of Todani III type cyst or choledochal cyst because the incision of the duodenal papilla under endoscope has particular therapeutic value. Although the diversity of ERCP has reduced the use of PTC, it is still an important diagnostic and therapeutic technique in biliary surgery. Patients with previous Roux-en-Y cyst jejunostomy or hepaticojejunostomy are considered for PTC. Besides, PTC is also suitable for the patient with type IV choledochal cyst when the intrahepatic choledochal cyst cannot be well displayed by ERCP due to biliary stricture or tumor. Percutaneous biliary drainage after PTC or biliary tract support after choledochojejunostomy can be performed to control sepsis caused by biliary tract infection. The role of PTC is limited when extensive cyst-jejunostomy prevents local preservation of the cyst and affects the complete display of the cyst, or when a giant extrahe-

patic bile duct cyst overlaps with the pancreaticobiliary junction, which makes the identification of related structures difficult (Fig. 13.5). PTC and ERCP have both advantages and disadvantages for the diagnosis of BD.  Both methods are invasive and require a large amount of contrast media to display the bile duct completely. Complications such as bleeding, bile leakage, acute cholangitis, and acute pancreatitis may occur. Although ERCP can confirm the existence of abnormal pancreaticobiliary juxtaposition, its clinical application has been dramatically limited because it is invasive, and children often need to be intubated under general anesthesia, but 3% to 10% of intubation fails.

13.3.4 Magnetic Resonance Cholangiopancreatography The purpose of Magnetic Resonance hydrography (MR hydrography) can be achieved by restraining the tissue signal around the biliary tract through a T2 weighted imaging technique to highlight the signal of water-­bearing biliary tract; a stereoscopic image of the cholangiopancreatic duct system can be obtained by the three-dimensional reconstruction of the image data through a computer. The advantages are as follows: • The full view of the biliary tree and the abnormal connection of the lower part of the pancreaticobiliary duct related to the etiology of the disease can be clearly and stereoscopically displayed free from the influence of pressure factors when the contrast agent is injected (Lee et  al. 2009a, b).

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• MRCP is a noninvasive examination, that is safe and comfortable, with no radiation damage, which is easy to operate on. • It is not affected by anatomic structural changes after surgery. • There are no complications such as biliary infection and acute pancreatitis. • The reconstructed images can be observed in multi-angle and multi-axial positions, and the lesions can be displayed stereoscopically and more intuitively. • It is suitable for patients who cannot tolerate ERCP and children who cannot cooperate with the examination. Compared with direct cholangiography, MRCP provides an equivalent or even superior BD imaging method, which can provide accurate anatomical development for infants and adults, and a reliable basis for surgical treatment. The dilated bile duct could be cystic, columnar, or diverticular, with high signal intensity on MRCP images. In cases complicated with stones, low signal filling defects could be observed against the background of high signal intensity. For Caroli’s disease, MRCP is currently considered to be the only ideal diagnostic method that can show normal bile ducts and cylindrical, cystic, or spindle-shaped dilated bile ducts, as well as the communication between the cystic lumen and the intrahepatic bile duct. This sign is a characteristic manifestation of the diagnosis of this disease (Fig. 13.6). In the case of cholangiocarcinoma, nodular parenchyma, asymmetric stricture of the bile duct, or truncation of bile duct are observed in MRI transverse axis and MRCP.

Fig. 13.6  MRCP showing the presence of a bile duct cyst and an abnormal connection of the lower segment of the pancreatic bile duct associated with the etiology of the disease

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ERCP has the possibility of over-evaluating the degree of bile duct stenosis, and the gas and pulsatile vascular artifacts in the gastrointestinal tract can cause pseudo-stricture of the bile duct. Meanwhile, MRCP is insensitive to mild stenosis and micro-calculi and is susceptible to volumetric effects and motion artifacts. Therefore, it is necessary to analyze the original image and conventional sequence images carefully to provide a reliable diagnostic basis for the formulation of a clinical operation plan. The anatomical structure of the pancreatic duct and cholangiopancreatic junction in MRCP is inferior to that of ERCP. However, with the improvement of MRI resolution, the limitations of MRI imaging in the diagnosis of biliary and pancreatic duct confluence have been steadily reduced.

13.3.5 Intraoperative Cholangiography Significant advances in the understanding of BD disease have revealed the truth that routine examinations may not meet the display needs for some specific diseases. However, intraoperative cholangiography can make up for the deficiency. Intraoperative cholangiography (IOC) can clearly display the shape of the common bile duct, especially the shape and location of the distal common bile duct. Understanding the shape of the intrahepatic bile duct and whether it is complicated with intrahepatic bile duct dilatation can sometimes help discover the rare vagal bile duct and complicated biliary malformation. Thus, the operation supplemented by cholangiography can effectively reduce postoperative complications (Liu et al. 2007). For patients with Todani type IVa, if only extrahepatic cysts are resected, without sufficient and adequate drainage of intrahepatic cysts, 23%–40% of the cases have postoperative complications such as recurrent cholangitis and liver abscess (Chijiiwa and Koga 1993). The reasons are related to cholestasis and biliary tract infection caused by relative stenosis of the intrahepatic bile duct at the opening of the common hepatic duct or membranous stenosis and septal stenosis. Intraoperative cholangiography can help to show the type and extent of intrahepatic bile duct stenosis. Intrahepatic cholangioplasty and high hepatic duct jejunostomy were performed according to the stenosis. However, IOC may have false-positive and false-negative results. If the injection of contrast media is insufficient, the intrahepatic bile duct will not fill; or the bubbles, mucus blocks, and blood clots in the bile duct may cause diagnostic doubts in the course of reading the radiographs. At this time, judgments should be made based on choledochoscopic observation, a bile duct probe for intrahepatic bile duct and distal common bile duct exploration, and intraoperative observation, to improve diagnostic accuracy.

13  Digital Surgical Diagnosis and Management of Biliary Dilatation

13.3.6 Radionuclide Hepatobiliary Scan Although radionuclide hepatobiliary imaging is useful in the diagnosis of bile duct cysts, its clinical value is limited because the information provided is functional rather than anatomical, which can only supplement cholangiography or stereoscopic imaging. Therefore, it can be used only when the symptoms are similar and difficult to identify.

13.3.7 Digital Medicine Technology With the rapid development of digital medicine technology, digitalization has become one of the developing directions of surgical medicine, and its application in biliary surgery has become more and more extensive. Three-dimensional visualization technology utilizes modern photoconductive technology and imaging technology to overcome the limitation that human eyes cannot see through or see directly. Thus, the spatial structure of the liver and its vascular system can be viewed panoramically and stereoscopically. The liver, surrounding organs, celiac vessels, and different vascular systems in the liver can be displayed three-dimensionally; with the aid of transparency modulation techniques and local magnification of the liver, the shape and distribution of the diseased bile duct are clearly defined through rotating stereoscopic observation of different angles and directions. The extent of the affected bile duct, the degree of dilation, as well as the relationship between the bile duct and hepatic artery, hepatic vein, and portal vein are shown. 3D printing technology can also be used to reconstruct the individual hepatobiliary system accurately, to determine and measure the distribution of the diseased bile duct and its spatial relationship with adjacent vascular structures. Meanwhile, visual virtual simulated operation on the model can help to make the operation plan, determine the best procedural path, guide the actual surgery, and improve accuracy and safety.

13.4 Differential Diagnosis and Management of Biliary Dilatation The clinical differential diagnosis of this disease is of great significance. With the deepening understanding of the etiology and pathology of BD, clinical diagnosis of it has become clearer. Targeted treatment can be carried out promptly, to achieve better clinical efficacy.

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13.4.1 The Differential Diagnosis of Biliary Dilatation 13.4.1.1 Differentiation of Diseases Characterized by Jaundice Periampullary Tumor Periampullary tumor predominantly occurs in the middle-­ aged or above, with a relatively short course; jaundice is aggravated progressively, often accompanied by itchy skin. The patient’s condition deteriorates rapidly and symptoms such as weight loss and anemia may occur; larger tumors may be palpable on the surface of the body and felt hard and nodular; imaging exams such as CT and MRI reveal a solid mass in the distal ampulla of the common bile duct, while no such imaging findings are demonstrated in the case of BD. Biliary Atresia Biliary atresia is a rare disease that occurs in infants; symptoms usually appear between 1 and 2  weeks after birth. Infants with biliary atresia develop cholestatic jaundice, dark brown urine, light yellow feces, and later developing into clay-colored stools, yellow staining of skin and sclera, and cholestatic portal hypertension or ascites in the later stages of the disease. B-ultrasound cannot detect the common bile duct, absence of gallbladder or atrophied gallbladder only, while BD is characterized by expansion of extrahepatic bile duct.

13.4.1.2 Differentiation of Diseases Characterized by Acute Epigastric Pain Acute Pancreatitis Mostly in adults, and causes such as overeating, calculus, or drinking may induce this disease; severe abdominal pain can involve the left back and left shoulder; the biochemical examination shows a significant increase in blood and urine amylase. B-ultrasound and CT show enlarged pancreas but normal choledochus. Acute Cholecystitis Mostly in adults, symptoms such as fever, pain in the right upper abdomen, tenderness, and muscle tension are obvious. Murphy’s sign is positive; real-time examination with B-ultrasound can clearly differentiate. Ascariasis of Biliary Tract Sudden pain in the right epigastric or epigastric cavity can be alleviated or restored to normal after attack; no mass in the

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right epigastric or epigastric abdomen exists; ultrasonic examination shows worm-like echo in the common bile duct and mild dilatation in the common bile duct, while no worm-­ like echo in BD.

13.4.1.3 Differentiation of Diseases Characterized by Abdominal Cystic Mass Hepatic Cyst Normal liver function. Patients with polycystic liver disease may be complicated with polycystic lesions of the kidney, pancreas, or spleen. Imaging methods such as CT or B-ultrasound can present the intrahepatic location of the cyst and a normal extrahepatic bile duct. Hepatic Echinococcosis The patients had contact with animals such as dogs and sheep in livestock areas. The cysts gradually increase; B-ultrasound and CT show intrahepatic space-occupying lesions and a normal extrahepatic common bile duct; eosinophils increased; Casoni test (hydatid intradermal test) positive rate reaches as high as 80%–95%. Retroperitoneal Cystic Masses Cystic teratoma or lymphangioma, for example, retroperitoneal cystic and BD can be differentiated basically by using B-ultrasound or CT, and the possibility of BD can be excluded by ERCP. Right hydronephrosis is not easily distinguished from BD by physical examination; however, the incidence of hydronephrosis is more common on the right side and the lumbar triangle is usually full, so B-ultrasound, intravenous pyelography (IVP), or endoscopic retrograde cholangiopancreatography (ERCP) can help determine right hydronephrosis and BD.

13.4.2 Treatment of BD

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ary drainage under the guidance of ultrasound should be performed. The operation of biliary drainage can help to alleviate critical conditions such as acute obstruction and infectious shock caused by infection. After the patient’s general condition is improved, resection of the diseased bile duct and reconstruction of the biliary tract should be performed.

13.4.2.2 Cholecystectomy, Resection of the Diseased Bile Duct + Roux-en-Y Anastomosis of Bile Duct and Jejunum This procedure can completely eliminate the cyst, improve drainage, significantly reduce the complications of the surgery, and prevent canceration, and thus, it is generally considered suitable for the management of Todani type I, II, and IVb. Because of repeated attacks of cholangitis in adults, there is visible inflammation around the cyst, and it is sometimes more challenging to remove the cyst entirely. In such cases, intracapsular resection can be performed, as proposed by Lily in 1978. Intracapsular resection means resection of the remaining part of the posterior wall adjacent to the portal vein, which was named the Lily procedure. The theoretical basis of this procedure is that the damage of the cyst itself is a potential canceration and the canceration only originates from the mucosa. Therefore, the purpose of preventing canceration can be achieved as long as the mucosal layer is eliminated. Cholangioduodenostomy and cholangiojejunostomy should be abandoned. 13.4.2.3 Liver Resection BD involving intrahepatic bile duct should be treated with drainage or lobectomy. The specific approach of liver resection depends on the distribution and extent of dilated hepatobiliary duct, the complication of hepatic lesion and residual liver function. The residual functional liver volume should be fully evaluated before liver resection. If the residual liver function is insufficient, the columnar dilated hepatic duct and its drainage segments should be properly preserved.

BD has a high canceration rate, which increases gradually with age, specifically, 0.7% under the age of 10 years, 6.8% between 10 and 20 years, and 14.3% over 20 years (Chijiiwa and Koga 1993). Therefore, surgical treatment should be performed as soon as possible once BD is diagnosed regardless of clinical symptoms.

13.4.2.4 Pancreaticoduodenectomy Pancreaticoduodenectomy is feasible when the lesions are associated with carcinogenesis of the lower common bile duct or obstructive jaundice caused by chronic pancreatitis.

13.4.2.1 Biliary Drainage For patients with acute suppurative inflammation, severe obstructive jaundice, and perforation of the biliary duct who cannot tolerate complex surgery, it is recommended that percutaneous transhepatic bile duct drainage and extra-bili-

13.4.2.5 Liver Transplantation Liver transplantation is a practical and final choice for diffuse BD with extensive lesions in bilateral hepatic lobes. Type A2 BD (Caroli’s disease involving the whole liver), complicated with severe hepatic fibrosis and portal hyper-

13  Digital Surgical Diagnosis and Management of Biliary Dilatation

tension, is feasible for liver transplantation. It is also feasible for types A, B, C, and D2 BD complicated with intrahepatic or hilar cholangiocarcinoma which cannot be cured by regular operation and has no extrahepatic metastasis. Some patients with Caroli’s disease even need liver and kidney transplantation.

13.4.2.6 Laparoscopic Surgery Since Farello first applied laparoscopic treatment of this disease in 1995, many scholars have begun to explore laparoscopic techniques. Because of the magnifying effect provided by laparoscopy, the operation is more precise, which is ­conducive to radical resection and correction of hepatic bile duct stricture. With the promotion of laparoscopic techniques and the accumulation of surgical experience, this technology has become one of the important techniques for the treatment of this disease. 13.4.2.7 Reoperation It is not uncommon for patients with bile duct cysts to be reoperated. The leading cause of reoperation is the mismanagement of various complications or the discovery of carcinogenesis. Removal of the duodenal or jejunal anastomosis of the original cyst, as well as the cystectomy and reconstruction of the biliary tract, are the main methods of reoperation. For those who have resected cyst, the critical point is to solve the stricture of choledochojejunostomy. At the time of reoperation, it should be noted that because the recurrence causes the cyst and the surrounding tissue to densely adhere, it is more difficult to separate and excise the cyst. The anterior wall and the bilateral wall can be excised, while the posterior wall can be removed only by removing the intima; leaving an outer layer to prevent the portal vein, hepatic artery, and even inferior vena cava from being damaged. For those with particularly dense adhesions, part of the wall can remain, and this remaining part may be damaged with iodine tincture, alcohol, or phenol after scratching. The anastomotic site should be enlarged to the left or right hepatic duct when there is too much resection near the hilar bile duct in the first operation, which results in the stricture of the anastomotic stoma. In order to avoid biliary stricture and stone formation, the condition of grade 2 or 3 bile duct in the liver should be fully explored. Liver lobectomy should be performed when intrahepatic lesions are found. 13.4.2.8 3D Visualization Technology to Assist Surgical Planning The majority of BD patients have experienced a long process of chronic cholangitis and chronic obstruction of the biliary tract. Their biliary tract structure has been distorted,

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deformed, dilated, or narrowed. Even adjacent liver tissues are affected, and pathophysiological changes occur, which makes the original complex intrahepatic conduit system more challenging to identify. Additionally, it brings uncertainty to the accurate determination of the anatomical relationship between blood vessels and bile duct before an operation. The 3D reconstruction images from CT and MRCP have a single color for the biliary tract and can only display different axial sections. It is impossible to simultaneously visualize the spatial relationship between the biliary system and the three sets of vascular systems in the liver and the whole liver. They are not real three-dimensional images, making it difficult for the operator to make a more accurate judgment on the variation of individual anatomy. In recent years, the rise of digital medical technology and the clinical application of three-dimensional visualization of human organs has brought new ideas for the diagnosis and treatment of BD. Many domestic scholars use proprietary 3D software to reconstruct, and assist in 3D reconstruction and operation planning for BD. 3D models of individualized liver, biliary tract, and blood vessel based on CT or MR data can be used to determine the shape and movement of intrahepatic and extrahepatic bile ducts, and whether they are accompanied by dilation, strictures, and stones; as well as to observe the anatomical relationship of the bile duct, the surrounding portal vein and hepatic vein at any angle. The risk of hemorrhage during operation can be avoided through judgment and evaluation of pathological changes, pre-­ planning, and treatment of possible complications such as intrahepatic bile duct dilatation, stenosis, or other complex biliary malformations and management of important peripheral vessels. Thus, reasonable, and quantitative surgical plans can be formulated, and individualized, precise biliary surgery can be performed. Fang Chihua’s research group has reconstructed the submillimeter CT data of 10 children with BD through the self-­ developed proprietary 3D visualization system for abdominal medical images and virtual surgical instrument simulation. The 3D images can be rotated and observed at will. A stereoscopic display of the shape and scope of the huge bile duct cyst and its relationship with the surrounding structures, as well as that of the stricture of the bile duct outlet and the confluence of the biliary duct at the lower end of the bile duct cyst, played a guiding role in the development of the surgical plan (Figs. 13.7 and 13.8). It is believed that in the near future, with the development and integration of computer technology, physics, and medical equipment technology, digital medicine will be further improved and become one of the essential auxiliary diagnostic and therapeutic means of BD.

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References

Fig. 13.7  In the MI-3DVS, the 3D image (liver and pancreas semitransparent substance) displays the size, shape, and scope of the cyst, as well as the relation of the cyst with peripheral vascular space stereoscopically; the 3D image also shows the distal bile duct opening of a bile duct cyst. With the guidance of this information, complete excision of the cyst during the operation was avoided without damaging the biliopancreatic junction

Fig. 13.8  Intraoperative exploration confirmed the presence of stricture in the distal bile duct opening of the choledochal cyst (on the right biliary duct probe)

Babbitt DP, Starshak RJ, Clemett AR.  Choledochal cyst: a concept of etiology. Am J Roentgenol Radium Therapy, Nucl Med. 1973;119:57–62. Bhavsar MS, Vora HB, Giriyappa VH. Choledochal cyst: a review of literature. Saudi J Gastroenterol. 2012;18:230–6. Chijiiwa K, Koga A. Surgical management and long-term follow-up of patients with choledochal cysts. Am J Surg. 1993;165(1):238–43. Dong J, Zhang X, Xia H, et  al. Cystic dilation of bile duct: new clinical classification and treatment strategy. Chin J Dig Sur. 2013;12(5):370–7. Lee HK, Park SJ, Yi BH, Lee AL, Moon JH, Chang YW. Imaging features of adult choledochal cysts: a pictorial review. Korean J Radiol. 2009a;10:71–80. Lee HK, Park SJ, Yi BH, et al. Imaging features of adult choledochal cysts: a pictorial review. J Korean J Radiol. 2009b;10(1):71–80. Liu Y-B, Wang J-W, Devkota KR, et  al. Congenital choledochal cysts in adults: twenty-five-year experience. J Chin Med J. 2007;120(16):1404–7. Miyano T, Yamataka A, Li L.  Congenital biliary dilatation. J Semin Pediatr Surg. 2000;9(4):187–95. Park DH, Kim MH, Lee SK, et al. Can MRCP replace the diagnostic role or ERCP for patients with choledochal cysts? J Gastrointest Endosc. 2005;62(3):360–6. Soares KC, Arnaoutakis DJ, Kamel I, Rastegar N, Anders R, Maithel S, et  al. Choledochal cysts: presentation, clinical differentiation, and management. J Am Coll Surg. 2014;219(6):1167–80. Yu ZL, Zhang LJ, Fu JZ, et al. Anomalous pancreaticobiliary junction: image analysis and treatment principles. J Hepatobiliary Pancreat Dis Int. 2004;3(1):136–9.

3D Visual Diagnosis and Management of Bile Duct Injuries

14

Ning Zeng, Silve Zeng, Jian Wang, Jiayan Yan, and Chihua Fang

14.1 Introduction Bile duct injuries refer to any damages to the original structure of the biliary system and abdominal changes in the flow of bile caused by traumatic or iatrogenic factors. Iatrogenic bile duct injuries are attributed to iatrogenic factors such as surgery or invasive diagnosis and treatment. Traumatic biliary strictures refer to the stricture or occlusion of bile ducts due to the injury of the biliary system, which is mainly divided into primary biliary stricture and secondary biliary stricture. The critical cause of benign stricture of the bile duct is inflammatory reaction and excessive collagen synthesis caused by bile leakage into the wall of the bile duct after bile duct injury. Typical clinical manifestations are obstructive jaundice, bile leakage, or biliary peritonitis. The management of bile duct injuries remains one of the most complex problems in abdominal surgery. At present, the diagnosis of bile duct injuries is assisted by cholangiography, ultrasound, and CT.  Surgical repair and biliary drainage are the main methods for the treatment of bile duct injuries, but partial hepatectomy or liver transplantation is perhaps the most appropriate treatment for patients with partial or complete liver atrophy.

14.1.1 Etiology and Classification of Bile Duct Injury 14.1.1.1 Etiology Anatomical Factors Variation of Cystic Duct  Typical anatomy of the cystic duct accounts for only 65%. The mode of confluence between

N. Zeng · S. Zeng · C. Fang (*) Zhujiang Hospital, Southern Medical University, Guangzhou, China

the cystic duct and the common hepatic duct may be angular, parallel, and spiral. Generally, there are two types of variations, including variation in the course of the cystic duct (The cystic duct is parallel to the common hepatic duct or right hepatic duct) and variations of confluence (The cystic duct obliquely crosses the front or rear of the common bile duct and converges into the left wall of the common bile duct; the cystic duct confluences into the back of the common hepatic duct, with high opening of the cystic duct in the right hepatic duct, the left hepatic duct, or the lower segment of the common bile duct; the cystic duct flows into the right common bile duct after encircling the common bile duct for one turn). In case of unusual type of cystic duct variation, bile duct injuries are easy to occur in an emergency operation. Variation of Cystic Artery  Generally, cystic artery is in the cystic triangle, arising from the right hepatic artery and then coursing to the gallbladder. About 20% of the cystic artery variations originate from arteries other than the right hepatic artery. Variations of bilateral cystic arteries and variations in the origin of gallbladder are common. Variation of Right Hepatic Artery  Caterpillar hump right hepatic artery, right hepatic artery, or gallbladder artery flows to the gallbladder before passing through the common bile duct. Anatomical Variant of the Gallbladder • Congenital absence of gallbladder. • Bilateral gallbladder. • Intrahepatic gallbladder. • Transverse gallbladder. • Left gallbladder. • Inversion of the gallbladder fundus (Phrygian cap). • Gallbladder in the left hepatic falciform ligament.

J. Wang · J. Yan Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_14

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Pathological Factors Stone incarceration in the neck of the gallbladder and gallbladder atrophy are high-risk factors for transection and defect of bile ducts caused by laparoscopic cholecystectomy (LC). Stones in the junction of the cystic duct and common hepatic duct, as well as right hepatic atrophy in cirrhosis can cause anomaly in bile duct movement and it can easily lead to bile duct injuries; local adhesion and dense infiltration caused by gastric neoplasms can alter the normal anatomy of the bile duct, and even that of the hepatic artery and portal vein. Forced transection, resection, or improper operation can easily damage the bile duct. Surgeon Factors In a large-scale study of 125,000 patients undergoing laparoscopic cholecystectomy, the incidence of biliary tract injury was 0.85%, which was three to four times higher than that of conventional laparotomy. Therefore, LC has always been listed as an important factor of biliary injury. Besides, factors such as the improper selection of incision, insufficient relaxation of anesthetic, inadequate timing of operation, surgeon’s incomplete knowledge of anatomical structures, lack of understanding of biliary tract variation, nonstandard operation, and rough surgical techniques would lead to clamping, excessive traction, and excessive dissection of common bile duct, and in blood pools. During the bile duct exploration, the mucous membrane of the lower part of the bile duct or papilla would be damaged due to rough operation; the placement of excessively thick T-tube and tight suture would also affect the blood supply of the common bile duct wall. In addition, the ischemic biliary disease caused by biliary dysfunction is another factor of bile duct injury and traumatic biliary stricture, which is elaborated in Chap. 9.

14.1.1.2 Classification of Bile Duct Injury At present, there is still a lack of comprehensive coverage in the international community, which can accurately summarize all the pathological characteristics of the various types of bile duct injuries and provide guidance for the prevention, treatment, and prognosis evaluation of various types of bile duct injuries. The commonly used international classification methods for bile duct injury include Bismuth-Corlette classification, Strasburg modification, and Stewart-Way classification (Mercado and Dominguez 2011). Some classifications are mainly established in the period of cholecystectomy, some by biliary stenosis, and others by biliary tract injuries caused by laparoscopic cholecystectomy. Therefore, there is no unified classification of bile duct injury at present. Bismuth-Corlette Classification Type I Low common hepatic duct (CHD) stricture, with a length of the CHD stump of >2 cm.

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Type II Middle stricture: length of CHD 2 cm from the confluence. Type E2 Injury