Joint imaging in childhood and adolescence [2 ed.] 9783030113421, 3030113426

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Sergio Lopes Viana Maria Custódia Machado Ribeiro Bruno Beber Machado

Joint Imaging in Childhood and Adolescence Second Edition 2019

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Joint Imaging in Childhood and Adolescence

Sergio Lopes Viana Maria Custódia Machado Ribeiro   Bruno Beber Machado

Joint Imaging in Childhood and Adolescence Second Edition 2019

Sergio Lopes Viana Hospital da Criança de Brasília José Alencar Hospital Ortopédico e Medicina Especializada (HOME) and Diagnóstico Clínica de Imagens Médicas Brasília Distrito Federal Brazil

Maria Custódia Machado Ribeiro Hospital da Criança de Brasília José Alencar Brasília Distrito Federal Brazil

Bruno Beber Machado Gastren Clínica Médica e Radiológica (Iúna-ES) Clínica Radiológica Med Imagem Clínica Radiológica Radial, Santa Casa de Misericórdia and Unimed Sul Capixaba Cachoeiro de Itapemirim Espírito Santo Brazil

ISBN 978-3-030-11341-4    ISBN 978-3-030-11342-1 (eBook) https://doi.org/10.1007/978-3-030-11342-1 Library of Congress Control Number: 2019932990 © Springer Nature Switzerland AG 2019 This work is subject to copyright. All rights are reserved 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 publisher, 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 publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

To the loving memory of my parents, Martiniano and Almira, and of Socorro Viana, who was my aunt, my mother and my father at the same time. To Angelica, Maria Fernanda, and Vinicius. Sorry for the absent time and thanks for being there for me, making everything worthwhile. To my family and my friends, for believing in me more than I believe in myself. Sergio Lopes Viana To my son Pedro and my daughter Julia. To Heloiza, my dear friend, thank you very much for your encouragement and affection. To Machado, my brother, mentor, and counselor. To my friend Sergio Viana, for his wise and skillful project coordination. Maria Custódia Machado Ribeiro To God, who always walks beside me, guiding my steps. To my beautiful, lovely, and patient wife Marina, for her extraordinary love, support, and understanding, and to our children, Heitor, Maria, and Clara, for providing true meaning to our lives. To my parents, Eberth and Ana, for showing me the value of work and study. To my dear friend Sergio Viana, for his leadership and togetherness. To all my friends, for their confidence and encouragement. Bruno Beber Machado

Foreword

Musculoskeletal imaging in the skeletally immature patient is a “gray area” often neglected by both musculoskeletal and pediatric radiologists. For the most part, knowledge on musculoskeletal imaging was built based on the assessment of adult individuals, which comprise the vast majority of the patients seen in daily practice. Furthermore, pediatric radiology as a subspecialty has traditionally focused on internal medicine, mostly thoracic and abdominal imaging, so that musculoskeletal diseases have received relatively little attention in the literature, most of the times concentrated on trauma and skeletal dysplasias, with even less emphasis on joint diseases. Therefore, this book is an opportune work as it aims to bring together these two worlds and provide a bridge between musculoskeletal and pediatric imaging by displaying the many facets that joint diseases may present in children and adolescents. The book begins with chapters dealing with the role of the different imaging methods in the pediatric patient and the peculiar features of the immature skeleton on imaging. These are topics of paramount importance, providing the reader with the necessary background in order to differentiate between normal and pathological findings. The following chapters cover a number of topics that are essential to anyone interested in this subspecialty: inflammatory and infectious arthropathies, sports-related injuries, accidental and non-accidental trauma, articular and periarticular tumors and pseudotumors, selected dysplastic conditions, and spinal diseases. Additionally, there is a brand-new chapter about autoinflammatory bone diseases, a hot topic that has been growing in importance and deserving increasing attention in recent years. Above all, the book is filled with images of great pictorial value, which play a pivotal role in understanding the key points of each of the diseases in question. This book is in its second edition and deservedly so, demonstrating the success that the authors achieved with their work by filling a gap in the medical literature in such a highly competitive international publishing market. It delivers comprehensive and up-to-date content with a richly illustrated material, written by professionals with vast scientific and practical knowledge, whose clear and concise language will certainly optimize the reader’s time and enhance knowledge absorption. The history of this book is further evidence of the high quality of the production of Brazilian authors in the field of imaging. Moreover, I would like to highlight another important aspect in being proficient in pediatric musculoskeletal radiology: the strategic one. I believe that, in a short time, artificial intelligence (AI) will be able to perform the most basic radiological diagnoses. Nevertheless, pediatric musculoskeletal radiology is anything but basic. Instead, it is complex and multifaceted, and mastering this area in this ever-changing time can be a very important differential in the career of the twenty-first-century radiologist. Finally, I would like to congratulate the authors for bringing to life a work of such quality, which will be very useful indeed in the imaging evaluation of our pediatric patients. It is an honor and a pleasure to be the one to introduce this book to the scientific community. 

Rodrigo Aguiar, MD Professor of Radiology Universidade Federal do Paraná Curitiba, Brazil vii

Preface

Pediatric radiology is considered the oldest subspecialty of diagnostic imaging. Nevertheless, there has been a steady and progressive decline in the number of pediatric radiologists in the last decades, along with a decreased emphasis on pediatric imaging during the training of radiology residents. On the other hand, advances in technology have provided us with imaging studies whose anatomic detail and diagnostic capabilities are better than ever before. The net result of this is a mismatch between what imaging methods can offer and what is effectively achieved by the radiologists, and this is particularly true in pediatrics: the aversion that many general radiologists present to pediatric studies is proverbial. In most cases, this happens because they are not fully acquainted with the normal appearance of the immature organism, sometimes being even unable to distinguish between normal and abnormal findings. Many books were already written about pediatric radiology, but only a few were devoted to musculoskeletal imaging. Just a handful was specifically dedicated to the immature joint, especially after the advent of cross-sectional imaging, and that is why our book intends to provide the reader with the basics of articular evaluation of children and adolescents, using a direct and concise approach. The chapters try to follow a logical and linear ordering, so that they can be read in sequence and, at the same time, serve as a reference source. Initially, the book describes the peculiarities of the different imaging modalities in the pediatric patient and the anatomical and/or developmental uniqueness of the growing skeleton on imaging. The infectious and noninfectious arthritides are discussed in the following chapters, as well as some conditions that are important in the differential diagnosis. The chapter on autoinflammatory bone disorders, a new and less known branch of autoinflammatory diseases that has become increasingly recognized in the last decade, emphasizes the importance of chronic multifocal recurrent osteomyelitis as the prototypical condition in this group. The articular and periarticular tumors and pseudotumors of the childhood are also studied, as well as Legg-Calvé-Perthes disease, another important pediatric entity. The chapter on musculoskeletal disorders related to hematologic diseases stresses mainly the importance of the hemophilic arthropathy and abnormalities associated with sickle cell disease. The subsequent chapters are about acute osteoarticular trauma and sports-related lesions, both increasingly found in pediatric patients. Spinal abnormalities inherent to the pediatric age group also deserve their own chapter, as well as some selected dysplastic and developmental abnormalities of the immature joint. The authors would like to express their gratitude to all those who contributed to this book, either providing images of great pictorial value or making a critical review of the manuscript. Many thanks to all in Springer too, for believing in this project, for their professional attitude, and for the cordial mindset. Last but not least, a special “thank you” to Dr. João Luiz Fernandes, one of the most prominent Brazilian radiologists, our fellow colleague and mentor. Many of the images in this book were obtained together during years of friendship and mutual ­collaboration, and many others were kind “gifts” from his personal archive. We gratefully acknowledge his precious help.

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In addition to all the foregoing, it goes without saying that even though written only by three authors, this book is the result of several decades of work, depicting the findings of hundreds of patients diagnosed and treated by hundreds of physicians. To all of them, patients and doctors alike, our acknowledgment and our gratefulness. Sergio Lopes Viana Maria Custódia Machado Ribeiro  Bruno Beber Machado

Preface

Contents

1 Imaging Methods and the Immature Joint: An Introduction���������������������������������   1 1.1 Introduction���������������������������������������������������������������������������������������������������������   1 1.2 Radiographs���������������������������������������������������������������������������������������������������������   1 1.3 Ultrasonography���������������������������������������������������������������������������������������������������   2 1.4 Nuclear Medicine�������������������������������������������������������������������������������������������������   6 1.5 Computed Tomography���������������������������������������������������������������������������������������   8 1.6 Magnetic Resonance Imaging�����������������������������������������������������������������������������  15 1.7 Dual Energy X-Ray Absorptiometry�������������������������������������������������������������������  22 Recommended Reading �����������������������������������������������������������������������������������������������  28 2 Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton���������������������������������������������������������������������������������������������  29 2.1 Introduction���������������������������������������������������������������������������������������������������������  29 2.2 The Immature Epiphysis and the Physis�������������������������������������������������������������  29 2.3 Pediatric Bone Marrow ���������������������������������������������������������������������������������������  40 Recommended Reading �����������������������������������������������������������������������������������������������  48 3 Imaging of Juvenile Idiopathic Arthritis �����������������������������������������������������������������  51 3.1 Introduction���������������������������������������������������������������������������������������������������������  51 3.2 Radiographs���������������������������������������������������������������������������������������������������������  51 3.3 Ultrasonography���������������������������������������������������������������������������������������������������  64 3.4 Magnetic Resonance Imaging�����������������������������������������������������������������������������  66 3.5 Computed Tomography���������������������������������������������������������������������������������������  83 Recommended Reading �����������������������������������������������������������������������������������������������  84 4 Imaging of Juvenile Spondyloarthritis and Pediatric Collagen Vascular Disorders�����������������������������������������������������������������������������������������������������  85 4.1 Introduction���������������������������������������������������������������������������������������������������������  85 4.2 Juvenile Spondyloarthritis�����������������������������������������������������������������������������������  85 4.2.1 Juvenile Ankylosing Spondylitis�������������������������������������������������������������  85 4.2.2 Juvenile Psoriatic Arthritis�����������������������������������������������������������������������  93 4.2.3 Arthritis Associated with Inflammatory Bowel Disease in Children�������  96 4.2.4 Reactive Arthritis������������������������������������������������������������������������������������� 102 4.3 Pediatric Collagen Vascular Disorders����������������������������������������������������������������� 106 4.3.1 Juvenile Dermatomyositis����������������������������������������������������������������������� 106 4.3.2 Juvenile Systemic Lupus Erythematosus������������������������������������������������� 108 4.3.3 Juvenile Systemic Sclerosis and Juvenile Localized Scleroderma ��������� 114 4.3.4 Mixed Connective Tissue Disease����������������������������������������������������������� 120 Recommended Reading ����������������������������������������������������������������������������������������������� 122 5 Imaging of Infectious Arthropathies in Children����������������������������������������������������� 123 5.1 Introduction��������������������������������������������������������������������������������������������������������� 123 5.2 Pyogenic Arthritis ����������������������������������������������������������������������������������������������� 123 5.3 Tuberculous Arthritis������������������������������������������������������������������������������������������� 135 xi

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Contents

5.4 Transient Synovitis of the Hip����������������������������������������������������������������������������� 144 Recommended Reading ����������������������������������������������������������������������������������������������� 152 6 Imaging of Chronic Recurrent Multifocal Osteomyelitis and Autoinflammatory Bone Disorders ������������������������������������������������������������������� 155 6.1 Introduction��������������������������������������������������������������������������������������������������������� 155 6.2 Chronic Recurrent Multifocal Osteomyelitis������������������������������������������������������� 155 6.2.1 Background ��������������������������������������������������������������������������������������������� 155 6.2.2 Role of Imaging Methods ����������������������������������������������������������������������� 155 6.2.3 Affected Sites������������������������������������������������������������������������������������������� 164 6.3 DIRA and Majeed Syndrome������������������������������������������������������������������������������� 171 6.4 SAPHO Syndrome����������������������������������������������������������������������������������������������� 178 6.5 NOMID and/or CINCA��������������������������������������������������������������������������������������� 179 Recommended Reading ����������������������������������������������������������������������������������������������� 181 7 Imaging of Articular and Periarticular Tumors and Pseudotumors��������������������� 183 7.1 Introduction��������������������������������������������������������������������������������������������������������� 183 7.2 Bone Lesions������������������������������������������������������������������������������������������������������� 183 7.3 Soft-Tissue Lesions��������������������������������������������������������������������������������������������� 191 Recommended Reading ����������������������������������������������������������������������������������������������� 212 8 Imaging of Legg-Calvé-Perthes Disease������������������������������������������������������������������� 213 8.1 Introduction��������������������������������������������������������������������������������������������������������� 213 8.2 Clinical Aspects��������������������������������������������������������������������������������������������������� 213 8.3 Imaging ��������������������������������������������������������������������������������������������������������������� 213 8.3.1 Radiographs��������������������������������������������������������������������������������������������� 213 8.3.2 Magnetic Resonance Imaging����������������������������������������������������������������� 219 8.3.3 Other Imaging Methods��������������������������������������������������������������������������� 228 Recommended Reading ����������������������������������������������������������������������������������������������� 233 9 Imaging of Musculoskeletal Manifestations Related to Pediatric Hematologic Diseases������������������������������������������������������������������������������������������������� 235 9.1 Introduction��������������������������������������������������������������������������������������������������������� 235 9.2 Hemoglobinopathies ������������������������������������������������������������������������������������������� 235 9.3 Coagulation Disorders����������������������������������������������������������������������������������������� 248 9.4 Hematologic Malignancies ��������������������������������������������������������������������������������� 258 Recommended Reading ����������������������������������������������������������������������������������������������� 268 10 Imaging of Accidental and Non-­accidental Articular Injuries in the Skeletally Immature Patient��������������������������������������������������������������������������� 269 10.1 Introduction������������������������������������������������������������������������������������������������������� 269 10.2 Peculiar Aspects of the Fractures of the Immature Skeleton����������������������������� 269 10.3 Pediatric Fractures of the Upper Extremity������������������������������������������������������� 278 10.4 Pediatric Fractures of the Lower Extremity������������������������������������������������������� 289 10.5 Traumatic Lesions of the Soft Tissues��������������������������������������������������������������� 291 10.6 Non-accidental Trauma������������������������������������������������������������������������������������� 293 Recommended Reading ����������������������������������������������������������������������������������������������� 317 11 Imaging of Sports-Related Musculoskeletal Lesions in Pediatric Patients����������� 319 11.1 Introduction������������������������������������������������������������������������������������������������������� 319 11.2 Apophysitis ������������������������������������������������������������������������������������������������������� 319 11.3 Osteochondritis Dissecans��������������������������������������������������������������������������������� 336 11.4 Stress-Related Physeal Injuries������������������������������������������������������������������������� 344 11.5 Stress Fractures ������������������������������������������������������������������������������������������������� 347 Recommended Reading ����������������������������������������������������������������������������������������������� 350

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12 Imaging Assessment of the Pediatric Spine: Selected Topics ��������������������������������� 353 12.1 Introduction������������������������������������������������������������������������������������������������������� 353 12.2 Juvenile Idiopathic Arthritis������������������������������������������������������������������������������� 353 12.3 Pyogenic (Bacterial) Spondylodiscitis��������������������������������������������������������������� 356 12.4 Spinal Tuberculosis������������������������������������������������������������������������������������������� 361 12.5 Spondylolysis����������������������������������������������������������������������������������������������������� 364 12.6 Scheuermann Disease ��������������������������������������������������������������������������������������� 370 12.7 Calcification of the Intervertebral Disc in Childhood��������������������������������������� 374 Recommended Reading ����������������������������������������������������������������������������������������������� 378 13 Imaging of Selected Dysplastic and Developmental Abnormalities of the Immature Joint������������������������������������������������������������������������������������������������� 379 13.1 Introduction������������������������������������������������������������������������������������������������������� 379 13.2 Madelung Deformity����������������������������������������������������������������������������������������� 379 13.3 Proximal Femoral Focal Deficiency ����������������������������������������������������������������� 379 13.4 Developmental Dysplasia of the Hip����������������������������������������������������������������� 383 13.5 Dorsal Defect of the Patella������������������������������������������������������������������������������� 386 13.6 Transient Lateral Patellar Dislocation��������������������������������������������������������������� 387 13.7 Popliteal Cyst����������������������������������������������������������������������������������������������������� 389 13.8 Discoid Meniscus����������������������������������������������������������������������������������������������� 389 13.9 Blount Disease��������������������������������������������������������������������������������������������������� 395 13.10 Freiberg Disease������������������������������������������������������������������������������������������������� 395 13.11 Tarsal Coalition ������������������������������������������������������������������������������������������������� 397 13.12 Spondyloepiphyseal Dysplasia and Multiple Epiphyseal Dysplasia����������������� 405 Recommended Reading ����������������������������������������������������������������������������������������������� 412

Abbreviations

CT Computed tomography Fat sat Fat-saturated MRI Magnetic resonance imaging PD-WI Proton density-weighted image STIR Short-tau inversion-recovery T1-WI T1-weighted image T2-WI T2-weighted image US Ultrasonography

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List of Figures

Fig. 1.1

Fig. 1.2

Fig. 1.3

Fig. 1.4

Fig. 1.5

Fig. 1.6

Radiographs of the left foot of a child performed with conventional (left) and digital (right) techniques. The digital radiograph has wider dynamic range when compared to the conventional one: the toes and the tarsal bones are equally well seen on the former, while only the middle portion of the foot is adequately exposed on the latter������������������������������� 2 Radiograph of the right knee of a 13-year-old female with juvenile idiopathic arthritis diagnosed 1 year earlier. Even though erosions are absent, osteoporosis and subtle increase in the size of the epiphyses are already seen, related to the hyperemic state. This radiograph will serve as a baseline study to monitor disease evolution and treatment response�������������� 3 Pelvic radiograph of a 22-year-old male with juvenile idiopathic arthritis since age 15. There is advanced arthritis of the left hip, with regional osteoporosis, erosions of the articular surfaces, narrowing of the joint space, and reduced size of the ipsilateral femoral head, which is markedly deformed��������������������������������������������������������������������������������������������� 3 Radiographs of a child with short stature showing generalized increase in bone density, with loss of definition of the corticomedullary junction (a). The fingers are short and stubby, and the distal phalanges are hypoplastic (b). Craniofacial abnormalities include macrocrania, trigonocephaly, parieto-occipital bossing, and straightening of the mandibular angles (c). These findings are typical of pyknodysostosis, with no need for additional investigation��������������������������������������������������������������� 4 In an appropriate clinical background, some radiographic patterns are almost pathognomonic. However, in most cases these findings usually appear late in the course of the disease, limiting their effectiveness for early diagnosis. In (a), there is a linear cortical lucency along the medial aspect of the proximal diaphysis of the right tibia associated with periosteal reaction and bone neoformation, which are highly suggestive of stress fracture in an adolescent runner. In (b), radiograph of a child with pain in the left hip shows that the femoral head is sclerotic and reduced in size, presenting a curvilinear subchondral lucency (crescent sign), findings typical of Legg-Calvé-Perthes disease. In both cases, MRI would be able to establish the diagnosis much earlier ��������������������������������������������������������������������������������������������������������������������� 5 Until the advent of modern imaging methods, only invasive radiographic procedures, such as conventional arthrograms (a), were able to demonstrate the epiphyseal cartilage, demanding sedation and intra-articular injection of iodinated contrast. This cartilage is much larger than the mineralized ossification nucleus (n), the only portion of the epiphysis that is detectable on radiographs. In (b), for comparison, coronal T1-weighted image (T1-WI, left) and fat sat T2-weighted image (T2-WI, right) of the left hip of a 3-year-old child are able to xvii

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Fig. 1.8

Fig. 1.9

Fig. 1.10

Fig. 1.11

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List of Figures

display both ossified and nonossified structures with high detail and in a noninvasive way, including the epiphyseal and articular cartilages, the acetabular labrum, muscles, and tendons��������������������������������������������������������������� 6 US of two distinct children with juvenile idiopathic arthritis and tenosynovitis involving the flexor pollicis longus tendon in the first patient (left images) and the flexor carpi radialis in the second one (right images). The tendons are elongated on sagittal scans (left images and upper right image) and appear as round structures on transverse scans (lower right image), with a fibrillar appearance. The synovial fluid in the tendon sheaths appears hypoechogenic, while amorphous echogenic foci are related to synovial thickening and debris. Even a 4-year-­old child (first patient) tolerates an US scan very well������������������������������� 7 US of an adolescent complaining of a nodule of elastic consistency and variable dimensions in the lumbar region. The image reveals a focal defect of the lumbar aponeurosis measuring 12 mm (calipers) and herniation of paravertebral muscle fibers��������������������������������������������������������������� 7 An 18-year-old female with autoimmune hepatitis since age 14 and taking immunosuppressant drugs presenting with left-sided pyogenic prepatellar bursitis. US scans (upper row) reveal thickening of subcutaneous tissue and filling of the prepatellar bursa with heterogeneous hypoechogenic material; peripheral hyperemia is seen on Doppler US (red-yellowish streaks in the second image). In the lower row, T2-WI (first image) discloses subcutaneous thickening and distension of the prepatellar bursa by heterogeneous content, mostly hyperintense. Post-contrast fat sat T1-WI (second image) reveals enhancement of the synovium and of the inflamed subcutaneous tissue, corresponding to the hyperemic zones seen on Doppler US. The non-enhancing material inside the bursa corresponds to debris and pus ��������������� 8 A 9-year-old boy presenting with a painless infrapatellar lump in the anterolateral aspect of the left knee. Doppler US (upper left image) discloses an oval well-delimited and heterogeneous hypoechogenic mass, with central areas of increased blood flow. Sagittal T1-WI (upper right image), transverse fat sat T2-WI (lower left image), and postgadolinium fat sat T1-WI (lower right image) reveal a sharply delimited lesion with heterogeneous signal intensity, predominantly hypointense on T1-WI and hyperintense on T2-WI, whose epicenter is near the patellar tendon. There is marked post-gadolinium enhancement, as could be inferred from the increased flow seen on Doppler US. The histopathological diagnosis was fibroma of the tendon sheath ��������������������������������������������������������������������������������������������������������� 9 Color Doppler (a) and power Doppler (b) US images of the right wrist of a patient with a presumptive diagnosis of palindromic rheumatism. Joint effusion and a thickened hyperemic synovium can be seen, with increased flow demonstrated on Doppler images, especially evident in (b)��������������������������������������������������������������������������������������������������������������������������� 9 US of a 5-year-old male with transient synovitis of the left hip disclosing synovial thickening and homogeneous synovial effusion. The growth plate and the epiphyseal cartilage are clearly seen as hypoechogenic structures������������������������������������������������������������������������������������� 10 Normal US scan of the right hip of a newborn with suspected developmental dysplasia. Both the femoral head and the acetabulum present preserved shape and size, and the articular relationships are normal (see Chap. 13)������������������������������������������������������������������������������������������� 10

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Fig. 1.14 Bone scintigraphy of a male adolescent with chronic osteomyelitis of the left femur showing markedly increased uptake in the distal twothirds of this bone. Even though quite evident, this scintigraphic finding is not specific, and several other conditions could cause a similar pattern. Scintigraphy is most often performed either in individuals with an already diagnosed disease, in order to assess its activity, or in concert with other imaging modalities in the investigation of patients with uncertain diagnosis��������������������������������������������������������������������� 10 Fig. 1.15 Bone scintigraphy revealing an area of increased uptake projected over the right frontal region (a). Though this finding is a reliable indicator of increased metabolic activity, it is far from being specific. CT of the head of the same patient (b) discloses a focal area of increased bone density affecting the outer table and the diploe of the right half of the frontal bone showing the typical “ground glass” appearance of fibrous dysplasia. Compare the high spatial resolution of CT with the low level of anatomic detail obtained with bone scintigraphy��������������������������������������������� 11 Fig. 1.16 Male adolescent with reactive arthritis. Bone scintigraphy (posterior view, a) shows increased uptake in the sacroiliac joints suggesting sacroiliitis, even though scintigraphic sacroiliac evaluation is particularly difficult in skeletally immature individuals; note the physiologic uptake in the distal physes of the forearms, which also occurs in normal sacroiliac joints. Coronal STIR (b) and post-contrast fat sat T1-WI (c) reveals areas of subchondral marrow edema and small erosions along the articular surfaces of both sacroiliac joints, bilaterally, with post-gadolinium enhancement, establishing the presence of sacroiliitis beyond any doubt������������������������������������������������������������� 11 Fig. 1.17 Reformatted CT images (a) and volume-rendered reconstructions (b) of the left ankle of a healthy 12-year-old male illustrate the multiplanar capabilities of this method, its high spatial definition, and the capacity to highlight different body tissues, like the bones (upper row, b) and the tendons (lower row, b). In (c), transverse CT images suffice to demonstrate marked trochlear dysplasia and signs of patellofemoral instability in a 12-year-old male, with a large osteochondral lesion in the anterior aspect of the lateral condyle and a displaced bone fragment in the intercondylar notch; nevertheless, volume-­rendered reconstructions (d) are an elegant way to better display the patellofemoral abnormalities and the relation among the avulsed fragment and the adjacent structures��������������������������������������������������������������������� 12 Fig. 1.18 A 12-year-old male with a history of trauma in his left knee 1 month earlier, persistent pain, and normal radiographs. Coronal fat sat PD-WI (left) shows joint effusion and extensive bone marrow edema in the distal femoral metaphysis, acutely delimited by the growth plate. There is a questionable infraction of the lateral cortex, immediately above the physis, which is widened and hyperintense in its lateral portion. Coronal reformatted CT image (right) demonstrates beyond any doubt the suspected fracture and the asymmetric physeal widening. Despite the adequacy of CT for bone assessment, this method has limited usefulness in the evaluation of the soft tissues (compare the level of detail of the intra-articular structures obtained with CT and MRI) and is completely insensitive for bone marrow edema����������������������������������������������� 15 Fig. 1.19 Transverse (a) and reformatted (b and c) CT images of the femur of a 16-year-old male with a diaphyseal osteoid osteoma. Even though the transverse image is sufficient to demonstrate the radiolucent tumoral

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Fig. 1.20

Fig. 1.21

Fig. 1.22

Fig. 1.23

Fig. 1.24

Fig. 1.25

Fig. 1.26

Fig. 1.27

List of Figures

nidus and a tiny central calcification, the reformatted images are useful to put in evidence the marked cortical thickening, endosteal sclerosis, and diaphyseal bowing that are also present��������������������������������������������������������� 16 Axial transverse CT image (left image) and axial fat sat T2-WI (right image) at the level of the anterior inferior iliac spines (AIIS) of a 13-year-old boy. Even though avulsion of the apophysis of the right AIIS is better demonstrated with CT because of its inherently superior spatial resolution, MRI can reveal edematous changes of the bone and soft tissues to which CT is insensitive ����������������������������������������������������������������� 17 Oblique reformatted CT images of a sessile osteochondroma (arrows) originating from the posterior surface of the body of the scapula in a 16-year-old female. CT is excellent for demonstration of cortical and medullary continuity between the osteochondroma and the parent bone, typical of this type of lesion. Furthermore, CT is also very useful in this particular case because of the anatomically complex structure of the scapula – which would render the lesion difficult to see on radiographs – and because of its multiplanar capabilities, making possible to obtain reformatted images in any needed plane in order to better depict the exostosis������������������������������������������������������������������������������������� 17 Talocalcaneal coalition in an 11-year-old male. Sagittal reformatted CT images (a) are diagnostic, revealing narrowing of the joint space of the middle facet and irregularity of the joint surfaces, as well as sclerosis of the subchondral bone. Nevertheless, most of the non-radiologists will prefer volume-rendered reconstructions (b) to envision the anatomic abnormality������������������������������������������������������������������������������������������� 18 Female adolescent with retropatellar pain in her left knee. CT-arthrography (a) reveals irregularity of the surface of the patellar cartilage with great detail (arrows), but it is limited for assessment of the cartilaginous substance. Transverse fat sat proton density-weighted image (PD-WI) at the same level (b) demonstrates the irregular contour of the articular cartilage in a noninvasive way and, in addition, shows abnormal intrasubstance signal intensity ������������������������������������������������������������� 18 Fat sat PD-WI of the left knee of a healthy 8-year-old child in the coronal (left) and sagittal (right) planes. MRI is able to assess noninvasively virtually all the osseous and non-osseous structures of the joint, providing excellent anatomic detail������������������������������������������������������� 19 Sagittal T1-WI and gradient-echo image (upper row) and transverse fat sat T2-WI and post-gadolinium fat sat T1-WI (lower row) of the right ankle of an 11-year-old hemophiliac patient. There is joint effusion and synovial impregnation by hemosiderin, which is markedly hypointense in all sequences (see Chap. 9), related to recurrent hemarthroses. Post-gadolinium image discloses a thickened and enhancing synovium, representing active inflammation and hyperemia������������������������������������������������� 19 A 9-year-old male with osteochondritis dissecans of the medial femoral condyle. The subchondral bone fragment is clearly seen on a coronal fat sat PD-WI, surrounded by bone marrow edema. Even though there is abnormal signal intensity in the adjacent epiphyseal cartilage, there is no discontinuity of the overlying articular cartilage����������������������������������������� 20 MRI of the left knee of a 16-year-old soccer player. Sagittal T1-WI (upper row) and fat sat PD-WI (lower row) disclose a non-­displaced tear of the posterior horn of the medial meniscus, with transection of the lower surface. Only MRI can demonstrate such abnormality noninvasively and with this level of detail ����������������������������������������������������������� 21

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Fig. 1.28 Male adolescent who sustained a traumatic injury to the lumbar region 1 month earlier (fall during a motocross race) presenting persistent low-back pain. Pelvic radiograph (upper left image) failed to disclose any noteworthy abnormalities. However, coronal fat sat T2-WI (upper right image) reveals bone marrow edema along the surfaces of the left sacroiliac joint, with increased signal intensity within the joint space and in the surrounding soft tissues. Transverse T1-WI and T2-WI (lower row) show widening of the left sacroiliac joint space and irregularity of the corresponding articular surfaces (“occult” posttraumatic diastasis)����������������������������������������������������������������������������������������� 22 Fig. 1.29 Anteroposterior radiograph (left) and coronal fat sat PD-WI (right) of the left knee of a 13-year-old male with a history of joint trauma while playing soccer and persistent pain. The radiograph obtained at initial evaluation is normal, while MRI reveals moderate bone marrow edema in the lateral femoral condyle, as well as an incomplete peripheral fracture of the cancellous bone (arrow). Edema of the soft tissues lateral to the affected femoral condyle is also evident on MRI ��������������������������� 23 Fig. 1.30 Tenosynovitis related to juvenile idiopathic arthritis in an adolescent. Transverse post-gadolinium fat sat T1-WI of the left hand discloses synovial enhancement in the flexor tendon sheaths. Even though all digits are affected, enhancement is more intense in the second and in the fifth flexor sheaths. Involution of this enhancement in subsequent studies is an indicator of good response to the treatment; conversely, progression of the findings indicates worsening of the inflammatory process������������������������������������������������������������������������������������������������������������������� 23 Fig. 1.31 Coronal fat sat T1-WI of the hips of a 6-year-old female with juvenile idiopathic arthritis. The first image (a), acquired immediately after intravenous administration of contrast, demonstrates joint effusion and synovial thickening in the right hip, with intense enhancement of the inflamed synovium. The joint fluid can be clearly differentiated from the thickened synovium, mostly adjacent to the acetabular labrum and to the medial cortex of the femoral neck. The second image (b), obtained in the same plane several minutes later, reveals diffusion of the contrast to the joint cavity, making it difficult to distinguish the synovial fluid from the synovium������������������������������������������������������������������������� 24 Fig. 1.32 Whole-body MRI of a young female presenting ovarian cancer and renal cell carcinoma (familial cancer syndrome) performed for detection of metastases, with no signs of distant disease. Whole-body MRI is unique as it provides global assessment of the organism without exposure to ionizing radiation. (Courtesy of Dr. Vinícius de Araújo Gomes, MD, Tesla Diagnóstico por Imagem, Brasília, Brazil) ��������������������������� 24 Fig. 1.33 DEXA of the lumbar spine (a) and of the whole body (b) of a healthy 11-year-old female showing that bone mineral density (BMD) is within the normal range when compared to a population with similar characteristics (note the graphs in the lower left corner of the images, in which BMD is plotted, and the charts on the right, where the values found are stated). On the other hand, the densitometric data (lumbar spine and whole body) of an 8-year-old female with osteogenesis imperfecta (c) reveals marked decrease of the BMD, with consequent increase in the relative risk of fractures ��������������������������������������������������������������� 25 Fig. 2.1 Radiograph of the right wrist of a healthy 8-year-old male showing that ossification has already begun in the carpal bones and in the distal radial epiphysis. However, as radiographs are fairly insensitive for

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cartilaginous assessment, only an indirect estimate of the thickness of the physes, of the cartilaginous anlage of the carpal bones, and of the epiphyseal cartilages can be made. The distal epiphysis of the ulna is entirely cartilaginous and completely invisible ��������������������������������������������������� 29 MRI of the right wrist of a young male whose age is similar to that of the child of Fig. 2.1. Coronal T1-WI (left), fat sat PD-WI (center), and gradient-echo image (right) show that the ossified portions of the carpal bones are isointense with the medullary bone seen in the metacarpals, the distal metaphyses of the radius and ulna, and the ossified portion of the distal epiphysis of the radius. Even though the distal epiphysis of the ulna is entirely cartilaginous, the epiphyseal cartilage is clearly seen, presenting low to intermediate signal intensity on T1-WI and intermediate to high signal intensity in the other sequences; a similar behavior is seen in the cartilaginous anlage of the carpal bones and in the cartilaginous portion of the distal epiphysis of the radius ����������������������������� 30 Coronal T1-WI (a) and fat sat T2-WI (b) of the left hip of a 3-year-old male. The secondary ossification center of the femoral head is already present, whose bone marrow has undergone complete conversion to the fatty type. On the other hand, the bone marrow of the femoral metaphysis and of the iliac bone presents predominance of the hematopoietic variety. The epiphyseal cartilage is predominantly isointense on T1-WI and shows intermediate signal intensity on fat sat T2-WI. There is a small focus of increased signal intensity on T2-WI in the apex of the epiphyseal cartilage, related to pre-ossification changes. The difference between the signal intensity of the yellow marrow (epiphyseal) and the red marrow (metaphyseal and diaphyseal) is even more conspicuous in sagittal images of the knee of a schoolaged child (c)��������������������������������������������������������������������������������������������������������� 31 In (a), coronal T1-WI (left) and fat sat T2-WI (right) of the left elbow of a 6-year-old female show that the ossification center of the capitulum is already filled with yellow marrow. The trochlear portion of the distal epiphysis of the humerus is completely cartilaginous, and increased signal intensity is seen in this cartilage on fat sat T2-WI, representing pre-ossification phenomena. In (b), volume-­rendered CT reconstructions of the left elbow of a 13-year-old male demonstrate that all the ossification centers are ossified, with partial fusion of the ossification center of the capitulum. Despite the excellent anatomic detail of bone provided by CT, very limited information can be obtained with this imaging method about the cartilaginous structures����������������� 32 Sagittal T1-WI (left) and fat sat T2-WI (right) of the right knee of a 13-year-old male. The secondary physis and the articular cartilage of the distal femur are clearly identified on fat sat T2-WI as linear areas of high signal intensity situated between the ossified and the cartilaginous portion of the epiphysis and along the joint surface of the epiphyseal cartilage, respectively. Bone marrow conversion is already complete in the epiphyses, while there is residual red marrow in the metaphyses, with its typical flame-shaped appearance������������������������������������������������������������� 33 Sagittal fat sat T2-WI of the left hip of a toddler. Although the epiphyseal cartilage displays predominantly intermediate signal intensity, there is low signal intensity in the weight-bearing zone, located in the uppermost portion of the epiphysis. In addition, foci of increased signal intensity are also found in the apex of the epiphyseal cartilage, related to ongoing ossification. The secondary physis appears

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Fig. 2.7

Fig. 2.8

Fig. 2.9

Fig. 2.10

Fig. 2.11

Fig. 2.12

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Fig. 2.14

as a thin hyperintense line surrounding the secondary ossification center, between the latter and the epiphyseal cartilage. The physis and the articular cartilage are also hyperintense if compared to the epiphyseal cartilage����������������������������������������������������������������������������������������������� 33 Sagittal PD-WI of the medial femoral condyles of two different children – the first is a 7-year-old subject (a) and the second one is a 13-year-old individual (b) – displaying the epiphyseal cartilage (*) as a structure of intermediate signal intensity between the hyperintense articular cartilage and the hypointense secondary ossification center. The ossification center is smaller, and the cartilage is proportionally thicker in younger children����������������������������������������������������������������������������������� 34 Sagittal fat sat T2-WI of the knees of two distinct boys, a 5-year-old (left) and a 7-year-old (right). There is rapid epiphyseal growth over time, with increase in the size of the secondary ossification center and reduction of the thickness of the epiphyseal cartilage. In the first image, marked hyperintensity is present in the primary spongiosa of the distal femur; a zone of increased signal intensity within the posterior portion of the epiphyseal cartilage of the femoral condyle represents ongoing ossification. The second image also shows hyperintensity of the posterior portion of the epiphyseal cartilage, more diffuse if compared to that seen in the first child. The focal area of decreased signal intensity seen in the weight-bearing zone of the epiphyseal cartilage of the femur in the second image is deprived of significance, typical of ambulating children���������������������������������������������������������������������������������������������� 34 Lateral view of the right knee of a 9-year-old female. The irregular contour of the posterior aspect of the femoral condyles is a normal finding, related to skeletal maturation������������������������������������������������������������������� 35 Radiographs (a) and reformatted CT images (b) of the right knee of a 2-year-old female. Normal spiculation of the contour of the ossified portions of the femoral condyles can be seen, mostly medial, related to activity in the bone and/or cartilage interface������������������������������������������������������� 35 Axial fat sat post-gadolinium T1-WI at the level of the proximal tibial epiphysis showing the normal vascular supply of the epiphyseal cartilage of a 3-year-old female as a web of punctate and linear areas of enhancement; the ossified nucleus of the epiphysis is seen in its central portion in the second image as an oval area of low signal intensity��������������������� 36 Coronal gradient-­echo images of the left knee of a 5-year-old child. The epiphyseal cartilages of the distal femur and of the proximal tibia are clearly distinguished from the adjacent articular cartilages: the latter are noticeably brighter, with signal intensity similar to that of the physeal cartilage. The smooth and regular physes are typical of younger children. As the menisci are composed of fibrocartilage, they appear as triangular structures with uniform low signal intensity ����������������������� 37 Coronal fat sat PD-WI of the left knee of a 15-year-old female displaying in detail the normal articular cartilages of the femoral condyles and of the tibial plateaus (asterisks)������������������������������������������������������� 37 Sagittal fat sat T2-WI of the right ankle of an 8-year-old female. The distal physis of the tibia presents the classic three-layered appearance, with high signal intensity in the physeal cartilage and in the primary spongiosa and an intervening line of low signal intensity corresponding to the provisional calcification zone. The physis is almost flat, a normal finding for the patient’s age. Foci of increased signal intensity are seen

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Fig. 2.17

Fig. 2.18

Fig. 2.19

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Fig. 2.21

List of Figures

in the medullary bone of the hindfoot and midfoot, deprived of significance����������������������������������������������������������������������������������������������������������� 38 Sagittal fat sat T2-WI of the right ankle of a 12-year-old female. If compared to the child of Fig. 2.14, the distal tibial physis is wavier and presents reduced thickness, findings related to progression of bone maturation. The calcaneal apophysis is already incorporated to the body of the bone��������������������������������������������������������������������������������������������������� 38 Sagittal fat sat T2-WI of the left knee of a 10-year-old male. There is physiological hyperintensity in the primary spongiosa of the distal femur and proximal tibia, which should not be confused with bone marrow edema ����������������������������������������������������������������������������������������������������� 38 Coronal fat sat T2-WI of the right knee of a 13-year-old male. The physes display their characteristic three-layered appearance, which is more evident in the proximal tibia. Intermediate to high signal intensity can be seen in the flame-shaped red marrow of the metaphyses, notably in the distal femur������������������������������������������������������������������������������������������������� 39 In (a), radiograph of the fingers of a 14-year-old male shows that the central physes of the distal phalanges are already closed and that only peripheral areas are yet to fuse. Reformatted coronal (left) and sagittal (right) CT images of the right ankle of a 13-year-old female (b) reveal a Salter-Harris type III avulsion fracture of the anterolateral portion of the distal tibial epiphysis (Tillaux fracture); note that the central, medial, and posterior portions of the physis are already closed. Closure of the distal tibial growth plate starts centrally and medially, progresses to posteriorly and laterally, and finishes at the anterolateral portion, rendering the epiphysis adjacent to the latter prone to avulsion injuries during the final stages of the process. The juvenile Tillaux fracture is a practical example of how the centrifugal pattern of closure of the growth plates may be of clinical importance ������������������������������������������������������� 39 In (a), anteroposterior and lateral views of the right ankle of a 20-yearold female display the physeal scar of the distal tibia as a thin dense line interposed between the metaphysis and the epiphysis below. In (b), sagittal T1-WI of the lateral femoral condyles and tibial plateaus of two distinct girls (a 15-year-­old [left] and a 25-year-old [right]) show the physeal scars as faint lines of low signal intensity; the red marrow – which displays intermediate signal intensity and is far more abundant in the younger individual – is confined to the metaphyseal regions and abuts the scars, sparing the epiphyses������������������������������������������������������������������� 40 A 14-year-old female complaining of pain in both knees. Coronal fat sat PD-WI (a) and sagittal T1-WI (b, left images) and fat sat PD-WI (b, right images) of the right knee reveal focal areas of bone marrow edema pattern centered about the physes of the distal femur and proximal tibia. Similar findings can be seen in the contralateral femur (c and d) ��������������������������������������������������������������������������������������������������������������� 41 A 13-year-old female complaining of right knee pain. Coronal T1-WI (upper left image) and fat sat T2-WI (upper right image) disclose bone marrow edema centered about the distal femoral physis, with questionable physeal narrowing. Post-gadolinium fat sat T1-WI (lower left image) discloses enhancement of the edematous bone marrow, while coronal reformatted CT image of the same knee (lower right image) shows sclerosis of the cancellous bone in the affected area and unequivocal focal narrowing of the growth plate. Focal periphyseal edema ������������������������������������������������������������������������������������������������������������������� 43

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xxv

Fig. 2.22 An 11-year-old male with aggressive sarcoma of the right proximal tibia. In addition to an anteroposterior view of the proximal leg (upper left image), transverse fat sat T2-WI (upper right image), coronal fat sat T2-WI (lower left image), and post-gadolinium fat sat T1-WI (lower right image) are also shown. The radiograph reveals heterogeneous bone sclerosis, spiculated periosteal reaction, and an adjacent soft-tissue mass. On MRI, the bone marrow of the proximal metadiaphysis of the tibia is diffusely infiltrated by the tumor, with an extensive subperiosteal component. Nonetheless, the proximal tibial epiphysis presents normal signal intensity, as the progression of the sarcoma was halted by the open physis ��������������������������������������������������������������� 44 Fig. 2.23 Coronal T1-WI of the legs of a 10-year-old male demonstrating the normal centrifugal pattern of bone marrow conversion, with preponderance of the hyperintense yellow marrow in the tibial diaphyses and residual red marrow predominantly located in the metaphyses, mainly the proximal ones����������������������������������������������������������������� 45 Fig. 2.24 Coronal T1-WI (left) and fat sat T2-WI (right) of the left hip of a 35-year-old female. There is residual red marrow intertwined with yellow marrow, the former predominantly found in the proximal femoral metadiaphysis and in the iliac bone. Red marrow is no longer present in the femoral epiphysis and in the greater trochanter, which are completely occupied by yellow marrow��������������������������������������������������������� 45 Fig. 2.25 Coronal T1-WI (left) and fat sat T2-WI (right) of the left hip of an 8-year-old male. A thick cartilaginous anlage is still present in greater trochanter apophysis, while ossification of the femoral head is far more advanced. The secondary ossification center of the femoral epiphysis shows complete conversion to yellow marrow, while red marrow is still predominant in the metaphysis����������������������������������������������������������������������������� 46 Fig. 2.26 Coronal T1-WI (left) and sagittal fat sat T2-WI (right) of the right shoulder of a 10-year-old male. The secondary ossification center of the proximal epiphysis of the humerus presents complete bone marrow conversion, and its signal intensity is identical to that of the subcutaneous fat in all sequences. Marrow conversion of the diaphyseal and metaphyseal regions is still happening, with predominance of red marrow in juxtaphyseal areas, characterized by intermediate signal intensity on T1-WI and high signal intensity on fat sat T2-WI ��������������������������� 46 Fig. 2.27 Sagittal T1-WI of the left knee of a 13-year-old male demonstrating the appropriateness of T1-weighted sequences for the assessment of bone marrow. While the epiphyseal yellow marrow presents high signal intensity, similar to that of the subcutaneous fat, metaphyseal red marrow presents low signal intensity. However, red marrow is hyperintense if compared to the skeletal muscle, excluding the possibility of marrow infiltration ������������������������������������������������������������������������� 47 Fig. 2.28 Sagittal fat sat proton density-weighted images of the left knee of an 8-year-old female complaining of heel pain. Scattered foci of increased signal intensity can be seen in the medullary bone of talus and in the midfoot, which are commonly found in healthy children and may represent residual red marrow or mechanical stress related to normal activity. The calcaneus (not shown) was normal��������������������������������������������������� 47 Fig. 2.29 Coronal images (fat sat T1-WI) of the left hip of a 13-year-old male before (left) and after (right) intravenous administration of gadolinium. Enhancement of the red marrow (mostly diaphyseal) is more intense than that of the yellow marrow (mainly epiphyseal and metaphyseal).

xxvi

Fig. 3.1

Fig. 3.2

Fig. 3.3

Fig. 3.4

Fig. 3.5

Fig. 3.6

Fig. 3.7

Fig. 3.8

List of Figures

Physeal enhancement is more intense than that seen in the epiphyseal cartilage����������������������������������������������������������������������������������������������������������������� 48 Radiographs of the ankle (a) and of the knee (b) of two distinct children with JIA showing soft-tissue swelling and displacement of periarticular fat planes. Even though bone erosions are not apparent, osteoporosis is already present, notably in the knee, where soft-tissue swelling is much more prominent������������������������������������������������������������������������� 52 Radiograph of the right hand of a child with JIA. There is soft-tissue swelling adjacent to the proximal interphalangeal joint of the fifth finger, more evident due to the density gradient created by the air and/or fat interface. Periarticular osteoporosis and periosteal reaction along the diaphyses of the proximal phalanges are also present ������������������������� 53 Radiographs of the hands and wrists of a child with early-stage JIA. Symmetric and bilateral periarticular osteoporosis is the main finding, predominantly found in the metacarpophalangeal joints. There is also subtle increase in the size of the epiphyses, mainly in the left wrist, without signs of erosive articular disease��������������������������������������������������� 53 Radiograph of the pelvis of a patient with long-standing JIA displaying findings related to chronic hyperemia. The proximal epiphysis of the right femur shows increased size, while there is diffuse osteoporosis associated with hypoplasia of the iliac bones and premature physeal closure on the left. Bilateral coxa valga is also present ��������������������������������������� 53 Radiograph of the hands of a patient with long-standing JIA (a) discloses deformities of several digits related to premature and asymmetric closure of the growth plates, with shortening of the second to the fifth metacarpals on the right and of the distal phalanges of both thumbs. Diffuse osteoporosis is also present, with abnormal alignment of the carpal bones and increased size of several epiphyses, bilaterally. Narrowing of joint spaces is obvious, mainly in the right radiocarpal joint, with invagination of the adjacent carpal bones. In (b), in another child with late-stage JIA, there is growth arrest due to premature physeal closure in both elbows. Marked periarticular osteoporosis is also present, with increased size of the distal humeral epiphyses, notably in the left elbow��������������������������������������������������������������������������������������� 54 In (a), anteroposterior view shows asymmetric growth of the knees, with increased size of the left distal femur when compared to the contralateral one (which also displays mild overgrowth); diffuse osteoporosis and growth recovery lines are also present, bilaterally. In (b), only the left knee is affected, with epiphyseal overgrowth of the distal femur and proximal tibia and mild ipsilateral osteoporosis; growth recovery lines are also present ����������������������������������������������������������������� 55 The left image reveals asymmetric bone maturation in the knees of a child with JIA: the epiphyses of the right femur, tibia, and fibula are irregular, bigger, and more developed than the contralateral ones, and regional osteoporosis is also present. In the right image, there is diffuse osteoporosis of the right elbow, as well as marked periosteal reaction along the distal humerus and epiphyseal overgrowth. Erosive articular disease is evident, mainly in the medial portion of the joint, as well as soft-tissue swelling����������������������������������������������������������������������������������������������� 56 Scanogram of an adolescent with advanced JIA (a) demonstrating advanced bilateral hip arthritis, more important on the left side, with joint space narrowing, widespread erosions, and remodeling of the joint surfaces. There is shortening of the right limb, with marked

List of Figures

xxvii

Fig. 3.9

Fig. 3.10

Fig. 3.11

Fig. 3.12

Fig. 3.13

Fig. 3.14

Fig. 3.15

Fig. 3.16

Fig. 3.17

Fig. 3.18

Fig. 3.19

leg-­length discrepancy. Growth recovery lines and periarticular osteoporosis can be seen in the knees and ankles. Anteroposterior view of the legs of another patient with JIA (b) shows diffuse osteoporosis and increased size of the epiphyses of the knees and ankles; the left limb is shorter than the contralateral as a result of abnormalities above the knee level. Tibiotalar slant is evident bilaterally��������������������������������������������� 56 Radiograph of the left wrist of a 16-year-old female with JIA since late childhood. There is mild osteoporosis, with narrowing of the radiocarpal joint space and disorganization of the proximal carpal row; a small cortical erosion can be seen in the distal third of the scaphoid. Despite the absence of extensive bone erosions, these findings are indicative of advanced cartilaginous destruction ������������������������������������������������� 57 Long-standing JIA affecting both hips, with bone erosions, narrowing of the joint spaces (more important in the right hip), and periarticular osteoporosis. Periosteal reaction is seen along the right femoral neck����������������� 57 Radiograph of the right knee of an adolescent with JIA and erosive changes. A large peripheral bone erosion can be seen in the proximal tibia, sparing the joint surface of the adjacent plateau����������������������������������������� 57 Radiograph of the left shoulder of a patient with long-­standing JIA. The joint surface of the humeral head is markedly irregular due to the presence of bone erosions. Cephalic migration of the humeral head is also present, related to complete tear of the rotator cuff. Glenoid deformity and bone remodeling are also present ������������������������������������������������� 57 In (a), radiograph of the left hip of a patient with advanced JIA demonstrates erosive arthropathy and secondary osteoarthritis due to extensive cartilaginous damage, with marked narrowing of the joint space associated with marginal osteophytes and subchondral sclerosis. In (b), radiographs of the left elbow of a 22-year-old male who suffered from JIA since age 1 year reveal premature and extensive osteoarthritis secondary to chronic arthritis��������������������������������������������������������� 58 Radiographs of the wrists of a 6-year-old child with JIA since 18 months old. There is diffuse osteoporosis and ankylosis of multiple joints, mainly carpometacarpal, as well as bilateral arthritis of the fourth metacarpophalangeal joints, abnormal bone modeling, and solid periosteal reaction along the metacarpal diaphyses ��������������������������������������������� 58 Symmetric and bilateral periostitis can be seen along the proximal and middle phalanges in both hands, notably from the second to the fourth digits. Periarticular osteoporosis is also present in this patient with JIA������������� 59 There is marked widespread osteoporosis in both ankles in this patient with long-standing JIA, as well as soft-tissue swelling and growth recovery lines ������������������������������������������������������������������������������������������������������� 59 This 14-year-old female with JIA developed diffuse osteoporosis after institution of systemic corticosteroid therapy, and treatment with oral alendronate was then started. Radiographs taken 10 months later disclosed dense metaphyseal bands in his long bones, here shown in the left ankle. Tibiotalar slant is also evident������������������������������������������������������� 60 Detail of a pelvic radiograph showing the classic “bone-­within-­bone” appearance in the right iliac bone of an adolescent with long-standing JIA������������������������������������������������������������������������������������������������������������������������� 60 Striated calcifications are seen in the infrapatellar fat pad of a young adult with late-stage sequelae of JIA who underwent several procedures for steroid infiltration in the knee. The radiographic

xxviii

Fig. 3.20

Fig. 3.21

Fig. 3.22

Fig. 3.23

Fig. 3.24

Fig. 3.25

Fig. 3.26

Fig. 3.27

Fig. 3.28

List of Figures

findings and the clinical data are highly characteristic about the nature of these calcifications, with no need for further investigation ����������������������������� 60 In the patients above, in addition to diffuse osteoporosis and radiographic evidence of arthritis, there is flexion deformity of the left elbow (a), both knees (b), and the first metatarsophalangeal joint of the left foot (c). In (d), deformity of the heads of the first metacarpals and subluxation of the corresponding metacarpophalangeal joints are evident, more important in the right hand, as well as epiphyseal overgrowth ����������������������������������������������������������������������������������������������������������� 61 Typical radiographic findings in the hands and wrists of two distinct patients with long-standing JIA. There are joint space narrowing and crowding of the carpal bones, which present a polyhedral appearance, opposite to the rounded contours that they exhibit in normal children. Diffuse osteoporosis can be seen in both patients, with carpal and metacarpal erosions in (a) and increased size of the epiphyses of the distal forearm in (b) ��������������������������������������������������������������������������������������������� 62 Radiographs of the knees of three different patients with JIA (a– c). Osteoporosis, epiphyseal remodeling, and widening of the intercondylar notch are found in varied degrees of severity in all of them. Bone erosions are also seen, more evident in (b)��������������������������������������� 62 Lateral view of the left knee of a patient with long-standing JIA showing diffuse osteoporosis, markedly increased epiphyseal size, soft-tissue swelling, and patellar “squaring.” These findings may be indistinguishable from those associated with hemophilia ����������������������������������� 63 Severely destructive arthropathy of the right hip is evident in this 36-year-old patient with late-stage sequelae of JIA. There is diffuse hypoplasia of the homolateral iliac bone, related to long-standing disease, as well as generalized osteoporosis in the affected hemipelvis��������������� 63 Aggressive arthritis affecting the left hip in a poorly controlled patient with long-standing JIA. Anteroposterior radiograph displays advanced joint destruction, with abnormal shape and irregular contour of the femoral head, bone remodeling, and acetabular protrusion ��������������������������������� 63 Avascular necrosis of the femoral head is a well-known complication of JIA. Anteroposterior (left) and lateral (right) radiographs evidence osteonecrosis of the left femoral head, with bone remodeling, abnormal epiphyseal shape, widening and shortening of the femoral neck, and subchondral lucencies. A small erosion can be seen in the right femoral head, with ipsilateral coxa valga��������������������������������������������������������������������������� 63 Planigraphy of the right temporomandibular joint (open mouth) of a patient with JIA revealing late-stage arthritic changes, with extensive destruction of the mandibular condyle, bone fragmentation, and erosions of the joint surfaces. Remodeling and enlargement of the glenoid fossa are quite evident, as well as sclerosis of the subchondral bone and flattening of the temporal eminence ����������������������������������������������������� 64 In (a), US of the knees (suprapatellar pouches, upper row) and of the ankles (lower row) of a child with JIA reveals heterogeneous joint effusions in these joints associated with bilateral and symmetric synovial thickening. In (b), US of another patient with JIA discloses a popliteal cyst containing heterogeneous fluid and marked synovial thickening; the thickened synovium displays prominent hyperemia on Doppler US in (c). (Courtesy of Dr. Telma Sakuno, MD, Hospital Universitário da UFSC, Florianópolis, Brazil (a) and Dr. Maria Montserrat, MD, Clínica Montserrat, Brasília, Brazil (b and c))������������������������� 65

List of Figures

xxix

Fig. 3.29 US of the anterior recess of the left ankle (upper row) and of the suprapatellar pouch of the right knee (lower row) of a 3-year-old female with JIA. There is thickening of the synovium (open arrows) and joint effusion in both joints, but no abnormal synovial Doppler signal was found. The suprapatellar pouch is completely filled by hyperechogenic and hypertrophic synovium. This child had a recent flare of disease activity and was being reevaluated after showing clinical improvement upon treatment������������������������������������������������������������������� 65 Fig. 3.30 Tenosynovitis of the extensor tendons of the right wrist in an 11-yearold male with JIA. The upper image displays a longitudinal scan along the third extensor compartment, while the lower image is a transversal section highlighting the fourth compartment. Both images show a hypoechogenic and heterogeneous halo surrounding the tendons (calipers and arrows), which maintain normal thickness and echogenicity. Histopathological analysis of the hypoechogenic tissue showed chronic hypertrophic synovitis����������������������������������������������������������������� 66 Fig. 3.31 Transverse T2-WI (a) and post-gadolinium fat sat T1-WI (b) of the hips of a 9-year-old female with long-standing JIA affecting both knees and arthritis of recent onset in the right hip. It is easier to identify right-­sided small to moderate joint effusion and synovial thickening by comparing the abnormal hip with the contralateral normal one. Synovitis is even more evident on (b), appearing as a thin enhancing stripe easily distinguished from the dark synovial fluid. Osteitis and erosions are not yet present����������������������������������������������������������������������������������� 67 Fig. 3.32 Contrast-enhanced fat sat T1-WI of the knees in the transverse and coronal planes (right knee, upper row; left knee, lower row) of a 7-year-old male with JIA since age 4. Symmetric and bilateral joint effusion and synovial thickening are evident, notably in the left knee. The thickened synovium shows enhancement and is more prominent in the intercondylar notches and adjacent to the lateral meniscus of the left knee. Meniscal hypoplasia is also seen in both knees, affecting predominantly the medial menisci. Focal irregularities can be seen in the corners of the tibial epiphyses on coronal images, corresponding to tiny cartilaginous erosions ����������������������������������������������������������������������������������� 67 Fig. 3.33 MRI of the left ankle of a child with JIA. In (a), images obtained in multiple spatial planes and using different sequences reveal synovitis, bone erosions (more evident in the tarsal sinus, with adjacent bone marrow edema), and joint effusion. In (b), gadolinium-enhanced fat sat T1-WI display enhancement of the inflamed synovium (allowing it to be distinguished from the synovial fluid), within bone erosions and in the edematous bone. Tenosynovitis is quite obvious, with fluid distension and contrast enhancement within the sheaths of the fibular tendons and of the posterior tibial tendon. Enhancement of the retrocalcaneal bursa is also evident����������������������������������������������������������������������� 68 Fig. 3.34 Sagittal fat sat T2-WI of the left knee of a child with JIA (a) disclosing a large joint effusion associated with synovial thickening and prominent lymph nodes in the popliteal fossa, posterior to the distal femoral diaphysis, without evidence of erosive arthritis. In another patient, post-contrast fat sat T1-WI of the right knee (b) reveal enlarged, enhancing lymph nodes in the popliteal fossa, as well as marked synovitis and joint effusion ��������������������������������������������������������������������� 69 Fig. 3.35 Transverse fat sat T2-WI (upper row, a) and post-gadolinium fat sat T1-WI in the transverse (lower row, a) and sagittal (b) planes of the

xxx

Fig. 3.36

Fig. 3.37

Fig. 3.38

Fig. 3.39

Fig. 3.40

List of Figures

right knee of a child with JIA. T2-WI demonstrate joint effusion, synovial thickening, and small cartilaginous erosions in the femoral trochlea and in the femoral condyles, with thinning of the cartilage of the lateral condyle. Contrast-enhanced images show that the synovial thickening is even more extensive than initially estimated as the inflamed synovium can be distinguished from the synovial fluid. Enhancement is also seen in the inflamed cartilages (which present irregular surfaces and superficial erosions) and in popliteal lymph nodes������������ 70 5-year-old female with JIA and active arthritis in the right wrist. In (a), coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) reveal extensive bone marrow edema affecting several carpal bones and the second metacarpal, with variable post-contrast enhancement, as well as joint effusion and an abnormally thickened and enhancing synovium. In (b), axial fat sat T2-WI (left) and post-­gadolinium fat sat T1-WI (right) disclose tenosynovitis of the extensors characterized by peritendinous edema and post-contrast enhancement affecting mostly the first and the second compartments; involvement of the extensor carpi ulnaris is more evident in post-gadolinium images. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)����������������������������������������������������������������������������� 71 19-year-old male with long-standing JIA and arthritis of the left hip. Coronal STIR image (left) and axial post-gadolinium fat sat T1-WI (right) show markedly thickened synovium occupying the joint cavity (asterisks), with post-contrast enhancement. There is also extensive thinning of the articular cartilages, more evident in the uppermost portion of the joint. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)����������������� 72 Young child with well-controlled JIA presenting with signs of inflammation in the left knee. Sagittal T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) disclose deep infrapatellar bursitis characterized by fluid distension of the bursa and marked synovial thickening and post-contrast enhancement. Mild intraarticular synovitis is also present, as well as enhancing lymph nodes in the popliteal fossa (right image)������������������������������������������������������������� 73 In (a), coronal STIR image (left) and post-gadolinium fat sat T1-WI (right) of the left wrist of an 18-year-old female with long-standing JIA display arthritis of the left wrist, with osteitis of the bones of the proximal carpal row, a large erosion of the distal scaphoid, and marked synovitis of the radiocarpal and distal radioulnar joints (note the difference on T1-WI between the thickened and abnormally enhancing synovium, which is peripherally located, and the centrally situated dark, non-enhancing joint fluid in the latter compartment). Thickening of the extensor carpi ulnaris and peritendinous post-contrast enhancement are also present, representing tendinopathy and/or tenosynovitis. In (b), axial fat sat T2-WI (left) and sagittal post-gadolinium fat sat T1-WI (right) of the right shoulder of a 15-year-old female with JIA show marked synovial thickening inside the joint and prominent postgadolinium enhancement; the synovial fluid in the subscapularis recess does not enhance. (Both cases courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)���������������������������������������������������������������������������������������������������������������������� 73 Sagittal fat sat T2-WI (left) and post-­gadolinium fat sat T1-WI (right) of the right knee of an 11-year-old male with JIA displaying small joint

List of Figures

xxxi

Fig. 3.41

Fig. 3.42

Fig. 3.43

Fig. 3.44

Fig. 3.45

Fig. 3.46

Fig. 3.47

Fig. 3.48

effusion and synovial enhancement inside the joint cavity and in the vicinity of the cruciate ligaments, with no signs of osteitis or erosions. An enhancing lymph node can be seen in the popliteal region. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil) ��������������������������������������������������������� 74 Imaging investigation of the right knee of a child with early JIA. Even though the lateral radiograph is entirely normal (first image), sagittal T1-WI (second image) and fat sat T2-WI (third image) clearly demonstrate a small joint effusion and a cartilaginous erosion affecting the posterior aspect of the epiphyseal cartilage of the medial femoral condyle, as well as osteitis and early erosive changes of the subchondral bone; a focal defect of the overlying articular cartilage was also present (not shown) ������������������������������������������������������������������������������� 74 Transverse post-gadolinium fat sat T1-WI of the right knee of a 4-year-old male with JIA. Joint hyperemia led to prominence of epiphyseal vessels of the proximal tibia, causing this bizarre pattern of cartilaginous enhancement����������������������������������������������������������������������������������� 75 Coronal fat sat PD-WI of the hips of a 19-year-old female with longstanding JIA. There is joint effusion in the right hip, as well as bone marrow edema in the ipsilateral proximal femur and in the subchondral bone of the corresponding acetabulum (compare with the normal left hip). A focal area of subcortical osteitis is seen in the lateral aspect of the right head and/or neck transition, without associated erosions ����������������������� 75 MRI of the left ankle of a child with early JIA. Sagittal fat sat T2-WI (upper left image) reveals a mottled pattern of bone marrow edema affecting the tarsal bones and a small tibiotalar joint effusion. Sagittal (upper right image) and transverse (lower images) post-­gadolinium fat sat T1-WI show enhancement of the edematous bone and of the inflamed synovium, as well as irregularity of the cartilage of the posteromedial portion of the talar dome. Only MRI is able to show these early findings with such a high level of detail��������������������������������������������� 75 Sagittal fat sat T2-WI of the left ankle of an adolescent with JIA. In addition to joint effusion, extensive bone marrow edema affecting several tarsal bones is also evident, as well as soft-tissue edema in the dorsum of the foot, findings compatible with tarsitis. Despite the extent of bone marrow edema, bone erosions are absent ����������������������������������������������� 76 Transverse T2-WI (upper image) and T1-WI (lower image) of the right hip of a patient with JIA. In addition to joint effusion, there are large bone erosions in the femoral head, filled with thickened synovium and synovial fluid��������������������������������������������������������������������������������������������������������� 76 Advanced arthritis of the left hip of a 22-year-old patient with JIA since mid-adolescence. Anteroposterior view (a) discloses marked narrowing of the joint space of the left hip, as well as abnormal shape of the femoral head and bone erosions. These findings are accurately depicted with MRI (b, coronal T1-WI [left] and post-gadolinium fat sat T1-WI [right]), which discloses extensive cartilaginous destruction, bone erosions, joint incongruity, and secondary osteoarthritis. Post-­ gadolinium enhancement is indicative of active inflammation����������������������������� 77 Sagittal T1-WI (upper images) and fat sat T2-WI (lower images) of the left knee of a young adult with long-standing JIA. There is marked increase in the size of the patella, whose bone marrow is diffusely edematous. In addition, joint effusion and synovitis are also present, with erosions of the femoropatellar joint surfaces����������������������������������������������� 78

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Fig. 3.49 Imaging investigation of the right knee of a 9-year-old female with active JIA. In (a), anteroposterior views of both knees demonstrate increased size of the epiphyses of the right distal femur and proximal tibia (compare with the normal left knee). In addition to epiphyseal enlargement, fat sat PD-WI in the coronal (b) and sagittal (c) planes disclose joint effusion and synovial thickening, as well as mild hypoplasia of the medial meniscus. Erosions and subchondral osteitis are absent ������������������������������������������������������������������������������������������������������������� 79 Fig. 3.50 16-year-old male with enthesitis-related JIA. Sagittal T1-WI (left) and fat sat T2-WI (right) of the left ankle reveal a thickened and heterogeneous Achilles tendon, as well as bone marrow edema of the calcaneus adjacent to its insertion, distention of the retrocalcaneal bursa, and edema of the surrounding soft tissues, findings compatible with tendinopathy and active enthesopathy. A small tibiotalar joint effusion is also present. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)����������������� 80 Fig. 3.51 Female patient with long-standing JIA. Coronal T1-WI (left) and fat sat T2-WI (right) of the right hip disclose joint space narrowing and a small joint effusion, as well as fluid distension of the trochanteric bursa. MRI and US are very suitable in the assessment of distended periarticular bursae and other fluid collections����������������������������������������������������� 80 Fig. 3.52 Sagittal T2-WI and T1-WI of the left TMJ of a 9-year-old male with long-standing JIA in the closed-mouth position (a) show flattening of the articular surface of the mandibular condyle along with remodeling and enlargement of the glenoid fossa, as well as flattening of the temporal eminence and a small joint effusion; additionally, coronal post-gadolinium fat sat T1-WI (b) reveals bilateral synovial enhancement (arrows), more prominent in the left side. Sagittal reformatted cone-beam CT images in closed-mouth (c) and openmouth (d) positions disclose bilateral bone deformities (including a severely hypoplastic and dysmorphic right condyle), limited excursion of both condyles, and tiny erosions in the irregular articular surfaces of both mandibular condyles, more evident on the right side; volumerendered reconstructions (e) display asymmetry of the mandibular rami, micrognathia and/or retrognathia, and limited jaw opening. (Courtesy of Dr. Glaucia Nize Martins Santos, DDS, MSc, Hospital de Base do Distrito Federal, Brasília, Brazil) ����������������������������������������������������������� 81 Fig. 4.1 Coronal STIR images of a 9-year-old female showing normal appearance of the sacrum and sacroiliac joints. The segmental and the lateral apophyses of the sacral wings appear as hyperintense transverse and marginal longitudinal bands, respectively, which are symmetric and uniform in thickness along both joints and should not be confused with bone marrow edema������������������������������������������������������������������������������������� 86 Fig. 4.2 An 18-year-old male with JAS and arthritis of the left midfoot and hindfoot since age 15. Lateral view (a) of the ankle demonstrates dorsal enthesophytosis and diffuse joint space narrowing in the midfoot, as well as and subcortical lucencies in the lowermost portion of the cuboid bone. In (b), sagittal T1-WI (upper row) and fat sat PD-WI (lower row) of the same ankle reveal arthritic changes, with joint effusion, cartilaginous thinning, synovial thickening, and bone marrow edema, as well as erosions in the talus, in the calcaneus, and in the cuboid. Post-gadolinium images (c) disclose enhancement of the thickened synovium and within bone erosions. Tarsitis is a peculiar

List of Figures

List of Figures

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Fig. 4.3

Fig. 4.4

Fig. 4.5

Fig. 4.6

Fig. 4.7

Fig. 4.8

Fig. 4.9

manifestation of juvenile spondyloarthritis, representing a combination of inflammation and bone proliferation that often leads to ankylosis. In (d), coronal T1-WI (left) and fat sat T2-WI (right) of the left shoulder of a 17-year-old male with JAS disclose joint effusion and synovial thickening, more evident in the axillary recess, as well as enthesopathy of the rotator cuff, with erosion and bone marrow edema adjoining the insertion site of the supraspinatus tendon, which displays mildly heterogeneous signal intensity ����������������������������������������������������������������������������� 87 Pelvic radiograph of a 27-year-old patient with JAS since late adolescence. There is severe osteoarthritis of the left hip (secondary to chronic arthritis) and right-sided sacroiliitis with pseudo-widening of the joint space, as well as ankylosis of the left sacroiliac joint and of the lower lumbar spine. Total replacement of the right hip joint is also seen, with wide lucent zones surrounding both components of the prosthesis, indicative of loosening ����������������������������������������������������������������������� 89 A 12-year-old male with JAS. Coronal CT image shows confluent subchondral erosions in the iliac surface of the left sacroiliac joint, with subtle sclerosis of the adjacent bone. This confluence leads to pseudo-widening of the sacroiliac joint space, similar to that seen in the right sacroiliac joint of the patient of Fig. 4.3������������������������������������������������� 89 Coronal STIR image (a) and post-gadolinium fat sat T1-WI (b) of a 13-year-old child with JAS and pre-erosive sacroiliitis. There is asymmetric subchondral bone marrow edema along the sacral surface and in the lowermost portion of the iliac surface of the right sacroiliac joint, with post-contrast enhancement. Joint spaces are preserved and erosions are absent. Similar (and more prominent) findings are seen in (c) in a 9-year-old male with axial spondyloarthritis and bilateral sacroiliitis (upper row, T1-WI; lower row, fat sat T2-WI) ����������������������������������� 89 MRI of the sacroiliac joints of two different patients. In (a), in a 19-year-old male with JAS since age 15, there is bilateral subchondral osteitis, which appears as areas of low signal intensity on T1-WI (left image) and high signal intensity on STIR (right image), as well as narrowing of the joint spaces and irregularity of the articular surfaces due to micro-erosions; a dominant bone erosion is seen in the upper half of the left sacral surface. Fatty replacement of the medullary bone is also present, mostly in the left sacral wing. In (b), MRI of a 14-yearold male with JAS and good clinical control shows narrowing of the left sacroiliac joint space and subchondral sclerosis, which appears as hypointense areas on transverse T2-WI (left images) and coronal post-­gadolinium fat sat T1-WI (right image). The absence of bone marrow edema or abnormal post-contrast enhancement is indicative of inactive disease����������������������������������������������������������������������������������������������������� 92 Bone scintigraphy of the same patient as in Fig. 4.4, posterior view. There is increased uptake in the lowermost portion of the left sacroiliac joint, indicative of active inflammation. Radiographs and CT are insensitive for assessment of disease activity������������������������������������������������������� 93 A 12-year-old female with severe JPA. Erosive arthritis can be seen in the interphalangeal joints of the third finger, mainly distal. Solid periosteal reaction along the diaphyses of the proximal phalanges is also present, from the second to the fourth digits. Extensive carpal and carpometacarpal ankylosis is evident������������������������������������������������������������������� 93 Radiograph of the feet of a child with JPA (magnification of the right forefoot in the right image). Erosive arthritis is seen in the

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Fig. 4.10

Fig. 4.11

Fig. 4.12

Fig. 4.13

Fig. 4.14

Fig. 4.15

Fig. 4.16

List of Figures

interphalangeal joint of the right hallux (“mouse ears” appearance), as well as ankylosis of the corresponding metatarsophalangeal joint. Arthritis of the metatarsophalangeal joint of the ipsilateral fourth toe is also evident, with the classic “pencil-in-cup” configuration characterized by bone remodeling and a saucer-like appearance of the joint surface of the proximal phalanx, in which the severely eroded metatarsal head articulates. Periostitis is seen along the proximal phalanx of the fifth toe on the right and along the diaphysis of the fourth metatarsal bone������������������������������������������������������������������������������������������� 94 Bilateral hip arthritis in a preadolescent girl with JPA, more important in the left hip, in which there is narrowing of the joint space and erosions of the articular surfaces��������������������������������������������������������������������������� 94 Deforming arthritis of the right elbow of a child with psoriasis. There is marked remodeling of the joint surfaces, with widening of the trochlear notch. Bone erosions are present in the distal humerus������������������������� 94 Reformatted sagittal CT images of the right foot (a and b) of a 10-yearold female with JPA and tarsitis showing bone erosions, subchondral sclerosis, bone proliferation, and enthesophyte formation at the site of attachment of the dorsal talonavicular ligament in the dorsal surface of the navicular bone, as well as densification of the adjacent subcutaneous tissue and diffuse osteoporosis. After successful therapy, reformatted sagittal CT images of the same foot obtained 1 year later (c, upper row) disclose complete bone healing and restoration of normal bone density, with residual deformity and mild sclerosis of the dorsal portion of the navicular; there is complete absence of edematous changes on sagittal fat sat T2-WI and T1-WI (lower row) performed on the same day��������������������������������������������������������������������������������������������������������� 95 Bilateral erosive arthritis of the metatar­sophalangeal joints can be seen in the feet of this female patient with JPA, more important in the right foot. Note the typical “pencil-in-­cup” deformity and lateral deviation of the toes, as well as marked osteoporosis ��������������������������������������������������������� 96 Arthritis of the manubriosternal joint in a 13-year-old female with JPA and 2 years of disease evolution. Reformatted coronal (a) and sagittal (b) CT images of the sternum disclose bone erosions and subchondral sclerosis in the articular surface of the body of the sternum for the manubrium, typical of chronic arthritis ��������������������������������������������������������������� 97 A 20-year-old male with long-standing peripheral JPA and unsuspected sacroiliac involvement. In (a), coronal fat sat T2-WI (left) and postgadolinium fat sat T1-WI (right) reveal unilateral right sacroiliitis characterized by extensive subchondral bone marrow edema (osteitis) both in the iliac and sacral joint surfaces and associated synovitis, with post-contrast enhancement within the joint space and in the inflamed bone. There is also evidence of capsulitis, with thickening, increased signal intensity, and contrast enhancement of the ipsilateral joint capsule (arrows), as well as subchondral sclerosis in the upper portion of the iliac surface. In addition to the above described findings, axial fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) in (b) disclose right-sided edematous changes of the posterior ligaments and subtle post-contrast enhancement (arrows) corresponding to active enthesitis���������������� 98 A 12-year-old female with polyarticular JPA and arthritis of the right hip. In (a), anteroposterior radiograph of the pelvis shows narrowing of the joint space of the right hip, with sclerosis of the subchondral bone of the acetabular roof. In (b), coronal T1-WI (left), fat sat T2-WI

List of Figures

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Fig. 4.17

Fig. 4.18

Fig. 4.19

Fig. 4.20

Fig. 4.21

Fig. 4.22

(center), and post-gadolinium fat sat T1-WI (right) reveal thinning of the articular cartilages, subchondral sclerosis, and osteitis in the acetabular roof and post-contrast enhancement of the bone marrow edema. There is diffusion of the injected gadolinium to the joint cavity������������� 99 Coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) of a patient with axial JPA showing bilateral sacroiliitis – more prominent on the right – with post-contrast enhancement of the inflamed bone marrow and synovium. There is a clear-cut erosion in the sacral articular surface of the left sacroiliac joint (arrow), more conspicuous on fat sat T2-WI and containing enhancing synovial tissue. Pseudo-­widening of the joint spaces is present, related to confluent micro-­erosions along the iliac surfaces of both joints������������������������� 100 Ankylosing tarsitis of the left foot in a girl with severe, progressive, and unrelenting polyarticular JPA. Lateral radiograph (a) reveals extensive ankylosis of the bones of the hindfoot and midfoot and severe erosive arthritis of the tibiotalar joint. T1-WI (left) and fat sat T2-WI (right) in the coronal (b) and axial (c) planes show active arthritis in the tibiotalar joint and demonstrate the ankylosis of the tarsal bones ��������������������� 100 Coronal STIR images of the sacroiliac joints of a male adolescent with axial JPA and bilateral sacroiliitis obtained at ages 15 (left) and 17 (right) disclosing changes in the pattern of joint involvement over time. In the first image, the right ilium exhibits extensive osteitis, which completely subsided 2 years later. Nonetheless, even though the sacral erosions are less well defined in the second image, bone marrow edema along the sacral surfaces – which was previously quite circumscribed – has a more diffuse appearance, mostly in the left side. Osteitis is also more prominent than before in the iliac side of the left sacroiliac joint������������� 101 Reactive arthritis with 6 months of evolution in a 15-year-old male adolescent. Radiograph of the left foot (a) discloses a subchondral lucency in the proximal phalanx of the third toe and faint periosteal reaction along this bone. US of the third metatarsophalangeal joint (b) shows heterogeneous joint effusion and marked synovial thickening (upper row); in spite of the prominent synovial proliferation, Doppler US shows only mild hyperemia (lower row). T1-WI (c, left) reveals joint effusion, circumferential bone erosions in the head of the third metatarsal, and synovitis, with bone marrow edema in the adjacent joint surfaces on fat sat T2-WI (c, right) and intense enhancement of the inflamed tissues on post-­gadolinium fat sat T1-WI (d). In addition to arthritis of the third metatarsophalangeal joint, bone scintigraphy (e) also discloses increased uptake on both sacroiliac joints, indicative of active sacroiliitis������������������������������������������������������������������������������������������������� 102 A 19-year-old male with reactive arthritis since adolescence. Pelvic radiograph (a) shows bilateral sacroiliitis with subchondral erosions and sclerosis. Lateral view of the left calcaneus (b) discloses signs of enthesopathy at the insertion of the Achilles tendon, with cortical irregularity, erosions, and bone neoformation ��������������������������������������������������� 105 A 14-year-old patient with reactive arthritis. In (a), fat sat PD-WI of the left knee in the coronal (left) and sagittal (right) planes show enthesopathy at the insertion of the quadriceps tendon (which is thickened and heterogeneous) and at the origin of the medial collateral ligament, with edema of the adjacent bone marrow and soft tissues. Mild synovitis is also present, and enlarged lymph nodes can be seen in the popliteal fossa. Bilateral sacroiliitis is evident on a transverse STIR

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Fig. 4.23

Fig. 4.24

Fig. 4.25

Fig. 4.26

Fig. 4.27

Fig. 4.28

Fig. 4.29

Fig. 4.30

Fig. 4.31

List of Figures

image (b, upper image), more extensive in the right side, with post-­ gadolinium enhancement on fat sat T1-WI (b, lower image)����������������������������� 105 A 12-year-old child with reactive arthritis in the left ankle and knee. Radiograph of the affected ankle shows only soft-tissue swelling, without further findings��������������������������������������������������������������������������������������� 106 Arthritis of the hands and wrists in a child with JDM. In spite of subtle subluxation of the metacarpophalangeal joints of the thumbs, more evident in the right hand, there are no signs of erosive disease. Softtissue swelling and generalized osteoporosis are also present, as well as symmetric and bilateral calcifications in the soft tissues of the distal forearms ������������������������������������������������������������������������������������������������������������� 107 A 3-year-old child with JDM. Radiographs show extensive and confluent plaques of calcification in the soft tissues of the upper limbs (a) and lower limbs (b), predominantly located in the elbows and in the proximal portions of the thighs and arms����������������������������������������������������������� 108 Chest X-ray of an adolescent with long-standing JDM. There are multiple calcifications in the soft tissues of the chest wall and of the arms��������������������������������������������������������������������������������������������������������������������� 108 Bizarre calcinosis is seen on the radiographs of this adolescent with JDM, involving the soft tissues of the upper limbs (a), of the pelvis (b), and of the lower extremities (c). Diffuse osteoporosis is also evident��������������� 109 Patterns of calcification in two distinct patients with JDM. In (a), lateral views of the left thigh of a 12-year-old female display large calcified masses and nodules of varied size and density in the posterior soft tissues of the lower limb, spanning the thigh, the popliteal region, and the proximal leg; marked osteoporosis is also present. In (b), radiographs of the left forefoot of a 15-year-old female show a cluster of densely calcified nodular deposits with varied sizes and shapes in the soft tissues plantar to the first metatarsal bone��������������������������������������������� 110 On US, calcifications in the left lower limb of a patient with JDM appear as hyperechogenic areas with posterior acoustic shadowing in the subcutaneous tissue (a–c), in the muscles, and along the fascial planes (d). In this study, there are micronodular (a and b), nodularclustered (c), and plaque-like (d) calcified deposits������������������������������������������� 111 CT of the chest of a child with JDM. Images in the transverse plane with soft-tissue window settings (a–d) demonstrate several superficial calcifications in the chest wall ��������������������������������������������������������������������������� 111 In (a), axial STIR images of the lower limbs of a 7-year-old boy with acute JDM disclose a symmetric pattern of muscle edema affecting mainly the gluteus maximus and the vastus lateralis muscles. In another patient, a 9-year old girl with JDM and active myositis, coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) of the thighs (b and c) and of the left hip (d) reveal a symmetric pattern of muscle edema affecting predominantly the adductor muscles and the proximal thighs, with post-gadolinium enhancement. In (e), transverse T2-WI of the pelvis of a 16-year-old female with chronic JDM shows striking atrophy and fatty replacement of the gluteal muscles, with hyperintense fat streaks permeating the muscle bellies. The anterior abdominal wall is markedly atrophic, with a strap-like appearance of the corresponding muscles. Symmetric and bilateral subcutaneous calcinosis is also present, mainly in the buttocks, appearing as hypointense streaks across the gluteal fat. (a is a courtesy of Dr. Bernardo Martins, MD, SARAH Brasília, Brasília, Brazil)������������������������������� 112

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Fig. 4.32 A 14-year-old female with JSLE since age 8 complaining of rightsided shoulder pain. Coronal (upper row) and sagittal (lower row) fat sat PD-WI demonstrate subacromial bursitis, with no evidence of erosive arthropathy��������������������������������������������������������������������������������������������� 114 Fig. 4.33 A 15-year-old female with JSLE. In (a), Doppler US of the second metacarpophalangeal joint of the right hand reveals joint effusion, synovial thickening, and increased blood flow. In (b), the extensor tendons at the level of the ipsilateral wrist are surrounded by heterogeneous, hypoechogenic material, corresponding to fluid and thickened synovium. Coronal STIR image (c, left) and post-gadolinium fat sat T1-WI (c, right) reveal nonerosive arthritis of the proximal interphalangeal joints and, more importantly, of the metacarpophalangeal joints, much more evident on post-contrast T1-WI due to the enhancement of the inflamed synovium. In (d), in addition to metacarpophalangeal arthritis, transverse STIR images (left) and post-gadolinium fat sat T1-WI (right) also disclose flexor and extensor tenosynovitis. Fluid distension of the flexor tendon sheaths is quite evident, as well as ruptures of the radial sagittal bands of the extensor mechanisms from the second to the fourth digits, with ulnar subluxation of the central extensor tendons������������������������������������������������������� 115 Fig. 4.34 Transverse post-gadolinium fat sat T1-WI of the left knee of an adolescent with JSLE displaying diffuse enhancement of the thickened synovium and erosions in the patellar cartilage. This patient had several areas of avascular necrosis in the proximal tibia and in the distal femur, the latter partially seen in this image as a geographic lesion in the medullary bone, displaying abnormal enhancement������������������������������������������� 116 Fig. 4.35 Coronal STIR images of both knees of a 15-year-old female patient with JSLE and lupus arthropathy demonstrating erosions in the joint surfaces of the lateral femoral condyles, surrounded by bone marrow edema and associated with small joint effusions ����������������������������������������������� 117 Fig. 4.36 Scleroderma “en coup de sabre” affecting the left hemiface of a 6-year-old male. In (a), transverse T1-WI demonstrates low signal intensity of the affected skin and subcutaneous tissue, with full-­ thickness atrophy of the soft tissues of the forehead and scalp. In (b), volume-rendered reconstruction of a three-dimensional sequence displays the typical lesion of this type of scleroderma, with a band-like depression of the skin surface affecting the left supraorbital region and the scalp ������������������������������������������������������������������������������������������������������������� 118 Fig. 4.37 Parry-Romberg syndrome in an adult patient, with 10 years of evolution. The upper image is a transverse CT section displaying marked atrophy of the right hemiface at the expense of the skin and subcutaneous tissue. In the lower image, a volume-rendered reconstruction shows facial hemiatrophy with extensive wasting of the soft tissues and prominence of the zygomatic arch under the skin surface. These findings are similar to those seen in the juvenile form of the disease����������������������������������������������������������������������������������������������������������� 119 Fig. 4.38 Radiographs of the left hand of a 5-year-old boy with juvenile scleroderma and sclerodactyly. In spite of the absence of erosive arthropathy, flexion deformities are already present, affecting the proximal interphalangeal joints from the second to the fifth digits. Diffuse osteoporosis is also evident������������������������������������������������������������������� 119 Fig. 4.39 Transverse fat sat T2-WI of the right wrist of a young female with scleroderma shows increased signal intensity in the soft tissues

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adjacent to the extensor and flexor tendons, related to tenosynovitis. The tendons present normal appearance������������������������������������������������������������� 120 Fig. 4.40 Radiographs of the hands of a 16-year-old female with juvenile scleroderma disclosing bilateral resorption of the distal phalanges and thinning of the soft tissues of the extremities of the fingers (acroosteolysis)����������������������������������������������������������������������������������������������������������� 120 Fig. 4.41 Widening of the periodontal ligament space is seen in the jaw of a patient with juvenile scleroderma, with periapical lucencies in several teeth. Partial edentulism is already present, even prior to the eruption of the third molars����������������������������������������������������������������������������������������������� 121 Fig. 5.1 Radiographs of the index finger of the right hand of a 6-year-­old female who sustained an open fracture of the middle phalanx 6 months earlier presenting spontaneous pus drainage from a fistulous orifice and marked soft-tissue swelling. There are signs of chronic osteomyelitis of the middle phalanx, with extensive osteolysis and bone sequestra involving the medullary cavity and in the distal interphalangeal joint. Destruction of corresponding joint surfaces due to PA is also evident, with lateral deviation of the distal phalanx��������������������������������������������������������� 124 Fig. 5.2 A 9-year-old female with acute osteomyelitis of the right distal femur and secondary contamination of the joint cavity of the knee joint. There are no osseous abnormalities on radiographs, although swelling of periarticular soft tissues can be seen, mostly suprapatellar and more evident in the lateral view. There are also loss of definition of periarticular fat planes and subtle widening of the joint space. Nonetheless, these are non-specific radiographic findings��������������������������������� 124 Fig. 5.3 Anteroposterior view of the right hip of a child with PA and disease onset less than 1 month earlier. There is osteoporosis of the proximal femur and narrowing of the coxofemoral joint space, as well as irregularity of the acetabulum. Such findings are compatible with advanced cartilaginous destruction��������������������������������������������������������������������� 125 Fig. 5.4 Radiograph of the proximal portion of the right arm of a young child with bacterial osteomyelitis and secondary contamination of the shoulder joint. There are lytic lesions associated with cortical destruction in the proximal metaphysis, as well as marked swelling of the periarticular soft tissues and widening of the proximal humeral physis ����������������������������������������������������������������������������������������������������������������� 125 Fig. 5.5 Pyogenic arthritis of the left hip with poor evolution. There is marked bone destruction with almost complete resorption of the left proximal femoral epiphysis and bone remodeling of the corresponding acetabulum; acetabular protrusion is evident as well, with striking acetabular incongruity. Left-sided osteoporosis is also present������������������������� 125 Fig. 5.6 Radiographs of the left elbow (first image) and of the right shoulder (second image) of a child with multifocal bacterial osteomyelitis and secondary articular contamination. There is metaphyseal osteomyelitis in the left distal and in the right proximal humeri, with permeative osteolysis, periosteal reaction, soft-tissue swelling, and epiphyseal involvement, the latter more evident in the shoulder. Osteomyelitis of the right femur and pyogenic arthritis of the ipsilateral hip were also present (not shown)��������������������������������������������������������������������������������������������� 126 Fig. 5.7 US of the hips of two distinct children, both with pyogenic arthritis. The upper images show longitudinal scans of the left hip joint demonstrating hypoechogenic joint effusion associated with irregular synovial thickening. In the lower row, there is heterogeneous material

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Fig. 5.8

Fig. 5.9

Fig. 5.10

Fig. 5.11

Fig. 5.12

Fig. 5.13

filling the joint cavity of the right hip, representing synovial thickening and joint effusion with suspended debris. The proximal epiphysis of the right femur is irregular and of reduced size, notably if compared to the contralateral one. (Courtesy of Dr. Telma Sakuno, MD, Hospital Universitário da UFSC, Florianópolis, Brazil)��������������������������������������������������� 126 Coronal STIR image (upper left image), transverse T1-WI (upper right image), and post-contrast fat sat T1-WI in the coronal and sagittal planes (lower images) of the hips and thighs of a 9-year-old female with right-sided septic coxofemoral arthritis. There are joint effusion in the right hip and bone marrow edema in the ipsilateral femur, which extends far beyond the subchondral bone, reaching the mid-diaphysis, indicative of associated osteomyelitis. Post-gadolinium enhancement of the edematous bone and of the proximal quadriceps is also evident������������� 127 Coronal T1-WI and fat sat T2-WI (upper row) of the left hip of a 12-year-old girl with PA reveal joint effusion and cartilaginous thinning, as well as edematous changes of the soft tissues of the proximal thigh and of the subchondral bone marrow of the acetabulum. Transverse post-contrast fat sat T1-WI (lower row) disclose intense enhancement of the thickened synovium and extensive destruction of the anterosuperior acetabulum, with cortical discontinuity and infiltration of the adjacent soft tissues, as well as contrast enhancement in the affected bone and soft tissues. This appearance may resemble aggressive bone tumors, like Ewing’s sarcoma�������������������������������������������������� 127 Transverse post-gadolinium fat sat T1-WI of the left hip of a 13-yearold male with PA. Heterogeneous joint effusion, marked synovial thickening, and infected collections in the soft tissues of the proximal thigh can be seen, with post-contrast enhancement. The femoral head is deformed, and its appearance is suggestive of slippage of the proximal femoral epiphysis as a complication of septic arthritis��������������������������������������� 128 Female adolescent with a chronic low-grade infection in the right forefoot. In (a) and (b), PET-CT demonstrates intense enhancement adjacent to the third metatarsophalangeal joint, initially interpreted as an infection of the periarticular soft-tissues with secondary involvement of the contiguous bone. MRI performed 3 months later (coronal STIR image (c) and sagittal post-gadolinium fat sat T1-WI (d)) demonstrates that the infection was primarily articular, with joint effusion, synovitis, and erosions in the head of the third metatarsal bone and edematous changes of the bone and of the adjacent soft tissues�������������������������������������������� 129 MRI of the left ankle of a 12-year-old male with PA. T1-WI (upper left image) and STIR image (upper right image) disclose tibiotalar joint effusion, metaphyseal osteomyelitis of the distal tibia, and a small juxtaphyseal intraosseous abscess, anteriorly situated. Post-­gadolinium fat sat T1-WI (lower images) demonstrate the intraosseous abscess with hypointense content and peripheral enhancement draining to the joint cavity through a cortical break. Synovial enhancement is also present, distinguishing the thickened synovium from the joint effusion ����������� 129 MRI of the same patient as in Fig. 5.2, performed on the same day (upper row, coronal fat sat T2-WI and sagittal T2-WI; lower row, coronal and sagittal post-gadolinium fat sat T1-WI). There is diffuse infiltration of the bone marrow of the distal femur, with post-­ gadolinium enhancement, as well as subperiosteal abscesses, extensive edema of the periarticular soft tissues, and contamination of the joint cavity, with joint effusion and synovitis������������������������������������������������������������� 130

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Fig. 5.14 MRI of the left hip of a child with PA (upper left image, coronal fat sat T2-WI; remaining images – transverse post-gadolinium fat sat T1-WI). There is a large and heterogeneous joint effusion on fat sat T2-WI, with extensive bone marrow edema in the proximal femur and acetabulum and edematous changes in the adjacent soft tissues. Post-gadolinium images display a large, complex soft-tissue abscess surrounding the hip, with thick and irregular enhancement, as well as adjacent myositis����������� 131 Fig. 5.15 Coronal T2-WI (left) and post-gadolinium fat sat T1-WI (right) of the left sacroiliac joint of a 13-year-old male with suspected PA of the right hip and a normal US scan. There are fluid within the sacroiliac joint space and edematous changes of the adjacent soft tissues, as well as a well-delimited intraosseous abscess in the subchondral bone of the upper third of the sacral surface surrounded by extensive bone marrow edema. Post-contrast images display diffuse enhancement of the aforementioned edematous abnormalities and peripheral enhancement inside the intraosseous abscess��������������������������������������������������������������������������� 131 Fig. 5.16 MRI of the right hip of a 10-year-old boy who underwent surgical treatment of PA, performed to clarify signs of ongoing sepsis. On coronal post-gadolinium fat sat T1-WI, one can identify a small joint effusion associated with synovial enhancement, extensive osteomyelitis of the ipsilateral iliac bone and a large, complex abscess involving the iliac and gluteal muscles, with surrounding myositis. There are also diffuse post-contrast enhancement of the infected bone, peripheral enhancement of the soft-tissue abscess, and feathery enhancement of the inflamed muscles������������������������������������������������������������������������������������������� 132 Fig. 5.17 A 9-year-old male with concomitant PA and osteomyelitis of the left hip. In (a), coronal (left) and axial (right) fat sat T2-WI show, in addition to moderate joint effusion, extensive bone marrow edema affecting the ilium and, more importantly, the ischium, as well as several soft-tissue collections in the periarticular muscles, more evident in the obturator internus, and widespread myositis. In (b), anteroposterior radiograph of the pelvis performed 1 month later displays marked osteoporosis in the left hip and bone destruction affecting the ischium, with cortical irregularity and permeative lytic lesions; mild narrowing of the ipsilateral coxofemoral joint space is also present��������������������������������������������������������������������������������������������������������� 133 Fig. 5.18 A 9-year-old male with PA of the left hip and a cutaneous fistula in the inguinal region. Coronal and axial fat sat T2-WI (left) and postgadolinium T1-WI (right) disclose joint effusion and synovitis, extensive bone marrow edema in the proximal femur with heterogeneous post-contrast enhancement (related to osteomyelitis), and widespread myositis, characterized by muscle edema and illdefined enhancement. There is an elongated and loculated abscess in the anterior soft tissues of the root of the thigh, which is more evident in the axial post-gadolinium T1-WI, with a thin peripheral rim of enhancement. The small area of enhancing bone marrow edema seen in the roof of the acetabulum may either correspond to focal osteomyelitis or be merely related to reactive osteitis ������������������������������������������������������������� 134 Fig. 5.19 A 9-year-old male with PA of the right hip and septicemia. CT scan reveals joint effusion, marked swelling of periarticular soft tissues, densification of the subcutaneous fat, and juxtaarticular abscesses. Gas bubbles can be seen in the collections, indicative of the bacterial nature

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Fig. 5.20

Fig. 5.21

Fig. 5.22

Fig. 5.23

Fig. 5.24

Fig. 5.25

Fig. 5.26

of the infection. (Courtesy of Dr. Arthemízio Rocha, MD, Hospital de Base do Distrito Federal, Brasília, Brazil) ��������������������������������������������������������� 135 CT scan of the left knee of a 2-year-old child with PA. Transverse images with bone (left images) and soft-tissue (central images) window settings and volume-rendered reconstructions (right images) reveal an extensive lytic lesion of the proximal metadiaphysis of the tibia, which extends across the growth plate to the proximal epiphysis. There is wide discontinuity of the posterior cortex, with bone sequestra in the medullary cavity, joint effusion, and a complex abscess in the posterior soft tissues of the proximal leg��������������������������������������������������������������������������� 135 Neonatal septic arthritis of the right shoulder. In the first image, radiograph of the affected joint reveals metaphyseal osteomyelitis of the proximal humerus, with a large intraosseous abscess and extensive periosteal reaction. In the following images, transverse CT sections corroborate the above described findings, disclosing bone destruction and cortical rupture. There is evidence of contamination of the joint cavity, with a large joint effusion and abscesses in the adjacent soft tissues. (Courtesy of Dr. Arthemízio Rocha, MD, Hospital de Base do Distrito Federal, Brasília, Brazil)����������������������������������������������������������������������� 136 A 17-year-old patient with PA of the right facet joint of L3–L4. In (a) and (b), transverse CT images evidence blurring and hypodensity of the soft tissues adjacent to the infected joint, without evidence of bone erosions. Transverse T2-WI (c) and post-gadolinium fat sat T1-WI (d) show fluid in the joint space extending deep to the ipsilateral ligamentum flavum, with discontinuity of the latter. Edema of the paravertebral soft tissues is also seen, as well as a right-sided posterior epidural phlegmon, with contralateral displacement of the thecal sac. The inflamed tissues exhibit diffuse post-contrast enhancement����������������������� 136 Transverse CT images (a) and (b) and sagittal reformatted images (c) of the right ankle of a 7-year-old female with tibiotalar PA and osteomyelitis of the tarsal bones. Destructive lesions in the talus and in the tarsal navicular bone are evident in the image with bone window settings (a), with sequestra in the affected bones and in the adjacent soft tissues. Diffuse edema of the periarticular soft tissues is evident in the images with soft-tissue window settings (b) and (c), as well as a large tibiotalar effusion. Post-contrast enhancement is seen in the thickened synovium and in the inflamed soft tissues����������������������������������������� 137 Late-stage sequelae of neonatal PA of the right hip. Radiographs show deformity of the proximal femur, delayed epiphyseal ossification, and remodeling of the acetabulum����������������������������������������������������������������������������� 139 Radiographs of the right elbow of a 7-year-old male with late-stage sequelae of PA (a). Joint deformity, bone remodeling, and articular incongruity can be seen, with radial shortening due to premature physeal closure. In (b), pelvic radiograph of a patient with late-stage sequelae of PA of the right hip shows coxofemoral dislocation and superior migration of the ipsilateral femur. The femoral head is articulated with the iliac bone, and the ipsilateral acetabulum is poorly developed, which are indicative of long-standing disease ��������������������������������� 139 Radiographs of the left shoulder of a young child with PA. The image on the left, obtained during the active stage of the disease, shows metaphyseal lucencies and cortical irregularity due to osteomyelitis. The second radiograph, taken after healing has occurred, reveals early fusion of the proximal humeral physis and marked residual deformity������������� 140

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Fig. 5.27 Late-stage sequelae of PA of the right hip, probably complicated with avascular necrosis. Scanogram demonstrates shortening of the right lower limb due to deformity of the ipsilateral hip, characterized by a mushroom-shaped femoral head, shortening and broadening of the femoral neck, flattening of the acetabulum, and early closure of the growth plate of the femoral head, with consequent joint incongruity ��������������� 141 Fig. 5.28 Sagittal post-gadolinium fat sat T1-WI of the right hip of a 3-year-old child with PA. In addition to the abnormalities usually found in septic joints, there is marked decrease in the enhancement of the proximal femoral epiphysis, as well as loss of its sphericity, related to avascular necrosis��������������������������������������������������������������������������������������������������������������� 142 Fig. 5.29 Late-stage sequelae of PA of the right wrist. There is evidence of right-sided proximal row carpectomy, with fusion of the bones of the distal row and the adjacent metacarpals, as well as residual deformity and atrophy of the ipsilateral bones ������������������������������������������������������������������� 143 Fig. 5.30 Tuberculous arthritis of the left knee in a young child. Phemister triad is present, with periarticular osteoporosis, predominantly peripheral erosions, and relative preservation of the joint space. Metaphyseal and epiphyseal lytic lesions are seen in the distal femur, representing active osteomyelitis (transphyseal spread) ������������������������������������������������������������������� 144 Fig. 5.31 Increased size and osteoporosis of the epiphyses are seen in this anteroposterior view of the right knee of a child with tuberculous arthritis, with preservation of the joint space and swelling of the periarticular soft tissues ������������������������������������������������������������������������������������� 144 Fig. 5.32 Radiographs of the right knee disclosing posterolateral lytic lesions involving the metaphysis and the epiphysis of the distal femur representing transphyseal dissemination of tuberculous osteomyelitis and concomitant tuberculous arthritis. There are discontinuity of the posterior cortex and diffuse swelling of the periarticular soft tissues, as well as posterior periosteal reaction along the distal femoral diaphysis������������� 145 Fig. 5.33 Radiographs of the left knee of a 2-year-old child. There is a welldelimited lytic lesion adjacent to the anterolateral physis in the proximal tibial metaphysis. Tuberculous osteomyelitis������������������������������������� 145 Fig. 5.34 Lytic lesion in the medial portion of the distal epiphysis of the right femur, ill-defined, associated with diffuse swelling of periarticular soft tissues, representing tuberculous osteomyelitis and concomitant arthritis ��������������������������������������������������������������������������������������������������������������� 146 Fig. 5.35 Lateral views of both knees of a 5-year-old child with left-sided tuberculous arthritis. The left epiphyses are osteopenic and show increased size when compared to the contralateral ones; ipsilateral soft-tissue swelling is also evident��������������������������������������������������������������������� 146 Fig. 5.36 Tuberculous arthritis of the left knee. There is increased size of the epiphyses and periarticular osteoporosis in the affected knee, with widening of the intercondylar notch, findings similar to those of hemophiliac patients. Subtle narrowing of the left joint space is noticeable ����������������������������������������������������������������������������������������������������������� 147 Fig. 5.37 Radiograph of the hips of a 15-year-old female with left-­sided tuberculous arthritis. There is narrowing of the left joint space, with irregular joint surfaces, regional osteoporosis, and premature physeal closure in the ipsilateral femur��������������������������������������������������������������������������� 147 Fig. 5.38 A 6-year-old male with chronic arthritis in the left knee and a skin fistula. Radiographs disclose advanced destructive arthritis, marked osteoporosis, abnormal shape of the epiphyses, large bone erosions

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Fig. 5.39

Fig. 5.40

Fig. 5.41

Fig. 5.42

Fig. 5.43

Fig. 5.44

Fig. 5.45

Fig. 5.46

Fig. 6.1

(mainly posterior, along the distal femur and the proximal tibia), and swelling of the regional soft tissues. Osteoarticular tuberculosis����������������������� 148 Pelvic radiographs of two distinct children, both with advanced tuberculous arthritis of the left hip joints. Bone destruction with marked periarticular osteoporosis and irregularity of the joint surfaces can be seen, as well as hypoplasia of the left iliac bones and of the left proximal femora. Pressure erosions can be seen along the medial aspect of the femoral neck in the second radiograph, as well as lateral subluxation of the hip����������������������������������������������������������������������������������������� 148 A 3-year-old child with severe malnutrition and palpable nodules in the frontal region. Anteroposterior skull radiograph shows two paramedian lytic lesions in the frontal bone. A small button sequestrum is seen in the left-sided lesion. Tuberculous osteomyelitis������������������������������������������������� 149 Multifocal tuberculous osteomyelitis affecting the right knee and the left elbow. There are lamellar periosteal reaction in the humerus and solid periosteal apposition in the tibia and in the bones of the forearm, with mild bone expansion. Periarticular osteoporosis is also present, with lucent lesions in the distal humerus and in the proximal ulna and tibia, as well as soft-tissue nodules along the dorsal aspect of the proximal forearm ����������������������������������������������������������������������������������������������� 149 In (a), fat sat T2-WI (upper images) and post-gadolinium fat sat T1-WI (lower images) disclose tenosynovial involvement of the flexor tendons of the hand in a young male with musculoskeletal TB. The flexor tendon sheaths are distended with heterogeneous hyperintense material on T2-WI containing septa and debris, more prominent in the first, second, and fifth digits, mostly the second one, which display postgadolinium enhancement. In (b), coronal gradient-echo images reveal numerous foci of low signal intensity within the tendon sheaths of the second and fifth digits, traditionally considered as related to hemosiderin deposition, even though some authors relate them to “rice bodies” or caseous changes. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)����������������������������������������������������������������������� 150 Transverse CT images of the right knee of a child with tuberculous arthritis. Synovial thickening and a large joint effusion are present, as well as a lytic lesion containing a bone sequestrum in the distal femur������������� 151 Longitudinal US scan of the left hip of a patient with tuberculous arthritis reveals a deeply seated, well-delimited heterogeneous abscess adjacent to the femoral cortex, with posterior acoustic enhancement ��������������� 151 US of the right hip of a child with TSH. Joint effusion is quite evident, as well as synovial thickening. Nevertheless, these are non-specific findings and do not allow to infer the real nature of the arthritis. Laboratory analysis of the synovial fluid was negative for infection and arthritis subsided with conservative treatment��������������������������������������������������� 151 Coronal T1-WI (a), STIR image (b), and post-gadolinium fat sat T1-WI (c) of the hips of a 4-year-old child with right-sided TSH. There are moderate joint effusion and synovial thickening in the right hip, with post-contrast enhancement of the synovium. Erosions and bone marrow edema are notably absent. Complete recovery was achieved with conservative measures��������������������������������������������������������������������������������� 152 An 11-year-old female with CRMO involving both knees and the right ankle. Anteroposterior radiograph (a) and reformatted coronal CT images (b) of the knees disclose several well-delimited lytic lesions in

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Fig. 6.2

Fig. 6.3

Fig. 6.4

Fig. 6.5

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the distal metaphyses of the femora and in the proximal metaphyses of the tibiae, adjacent to the growth plates, surrounded by extensive bone sclerosis. The abnormalities are more pronounced in the left knee, where increased size of the epiphyses is also present, as well as a lytic lesion associated with marked sclerosis in the proximal tibial epiphysis. In (c), in addition to metaphyseal lytic lesions surrounded by bone sclerosis, reformatted sagittal CT images of the right ankle reveal a solid periosteal reaction along the posterior cortex of the distal tibia. In (d) and (e), coronal fat sat T2-WI (upper images) and post-gadolinium fat sat T1-WI (lower images) show disease progression over a period of 7 months: bone marrow edema in (e) is much more extensive than it appeared in (d), especially in the right knee, as well as gadolinium enhancement, which is more evident in the lytic lesions than in the edematous bone. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)��������������������������������������������������������������������������������������������������� 157 Radiographs of both knees (a) and reformatted coronal and sagittal CT images of the right knee (b) of a 12-year-old female with CRMO show symmetric and bilateral involvement of the metaphyses of the femora, tibiae, and fibulae; clustered lytic lesions surrounded by sclerosis can be seen adjoining the growth plates in all involved bones with the exception of the left fibula, where only sclerosis is present. The sclerotic component is much less important than that seen in 6.1. In (c) and (d), coronal and sagittal fat sat PD-WI of the right knee of a different patient (12-year-old girl) acquired 6 months apart disclose reactivation of previously quiescent CRMO: the upper images reveal only minimal juxtaphyseal bone marrow edema, more evident in the distal femur, while the lower images show worsening of the edematous changes and the appearance of small hyperintense metaphyseal nodules that were previously absent (circled areas)��������������������������������������������������������� 160 Axial CT image (a, left), sagittal T1-WI (a, center), and fat sat PD-WI (a, right) of the left hip of a 12-year-old female with CRMO displaying lytic lesions in the proximal metaphysis of the femur, with extensive bone marrow edema extending to the proximal diaphysis and moderate joint effusion; mild bone sclerosis surrounding the lesions is present in the CT image. In (b), in addition to increased uptake in the left hip, a bone scintigraphy reveals abnormal focal uptake adjoining the distal growth plate of the left femur, which corresponds to another focus of osteitis. The physiological uptake in the growth plates makes areas of abnormal bone activity harder to identify����������������������������������������������������������� 162 A 9-year-old female with CRMO. In (a), sagittal fat sat PD-WI (left) and T1-WI (right) of the right ankle disclose juxtaphyseal metaphyseal lesions surrounded by bone marrow edema in the distal tibia and fibula, with subtle edema of the adjacent soft tissues; bone marrow edema is also present in the epiphysis. In (b), additional coronal fat sat PD-WI with increased field-of-view performed ad hoc reveal similar findings in the contralateral tibia and fibula. In (c), sagittal fat sat PD-WI (left) and post-gadolinium fat sat T1-WI (right) reveal inflammatory involvement of the right calcaneal apophysis of the same child, with enhancement of the edematous changes of the bone and adjacent soft tissues����������������������������������������������������������������������������������������������������������������� 163 Imaging studies of the right ankle of a 12-year-old male with CRMO. In (a), radiographs show several juxtaphyseal lucent areas in

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the distal metaphyses of the tibia and fibula. In (b), MRI images acquired in different planes and sequences reveal, in addition to the lesions described on radiographs, similar lesions abutting the physis of the calcaneal apophysis, as well as extensive surrounding bone marrow edema (which is also present in the epiphyses) and inflammation of the adjacent soft tissues��������������������������������������������������������������������������������������������� 165 Fig. 6.6 Radiographs of the left knee of a child with CRMO. There is extensive bone sclerosis in the metaphyses of the distal femur and proximal tibia, more pronounced in the latter, in which there are confluent juxtaphyseal erosions and widening of the adjacent growth plate. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)����������� 166 Fig. 6.7 An 11-year-old female with CRMO. In (a), axial T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) of the left foot disclose diaphyseal thickening and circumferential periosteal reaction related to the second metatarsal bone, with edema of the bone marrow and of the adjacent soft tissues, involvement of the distal physis, and marked post-gadolinium enhancement. Additional lesions are present adjoining the physis of the greater trochanter (b) and (c), with associated bone marrow edema and inflammation of the adjacent soft tissues����������������������������������������������������������������������������������������������������������� 167 Fig. 6.8 In (a), chronic inflammation of the left proximal radius related to long-standing CRMO in a 10-year-old boy led to physeal widening of the proximal radius, irregular contours of the adjacent metaphysis and epiphysis, and flaring of the proximal metadiaphysis; there is also a multilayered periosteal reaction, as well as bone sclerosis mixed with lucent areas. In (b), long-standing CRMO of the proximal tibia in another child led to hyperostosis, with cortical thickening and narrowing of the medullary canal; heterogeneous bone sclerosis is also present, with intervening lucent areas����������������������������������������������������������������� 170 Fig. 6.9 An 11-year-old female with CRMO. In (a) and (b), reformatted CT images show lytic lesions abutting the growth plate of both fibulae, with surrounding sclerosis. In (c), MRI images of the right ankle reveal bone marrow edema adjoining the aforementioned lesions, with transphyseal involvement. In (d), coronal and sagittal PD-WI of the right knee of the same child disclose juxtaphyseal lytic lesions in the distal femur and proximal tibia, surrounded by extensive bone marrow edema extending to the adjacent epiphyses and associated with inflammation of the contiguous soft tissues (note the presence of fluid within the deep infrapatellar bursa) ������������������������������������������������������������������� 171 Fig. 6.10 A 13-year-old girl with CRMO since age 8. The patient’s guardians opted to abandon the pharmacologic treatment, and the child remained drug-free for almost 5 years, evolving with progressive genu varum and receiving only orthopedic support. A panoramic radiograph of the lower limbs shows severe genu varum with bilateral epiphysiodesis of the distal femora. Note the typical juxtaphyseal lytic lesions in the long bones of both lower limbs����������������������������������������������������������������������������������� 173 Fig. 6.11 A 9-year-old male with CRMO and spontaneous patellar fracture. Sagittal fat sat PD-WI (left) and T1-WI (right) disclose an incomplete transversal fracture involving the cancellous bone of the anteriormost portion of the upper third of the patella, surrounded by bone marrow edema���������������������������������174 Fig. 6.12 Clavicular involvement in a 14-year-old male with CRMO. In (a), anteroposterior radiographs reveal widening of the medial third of the

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Fig. 6.13

Fig. 6.14

Fig. 6.15

Fig. 6.16

Fig. 6.17

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right clavicle, with mixed lytic and/or sclerotic appearance of the bone and soft-tissue swelling. In (b), axial fat sat T2-WI (left) and postgadolinium fat sat T1-WI (right) disclose edematous changes of the clavicular bone and of the adjacent soft tissues, which show enhancement on post-contrast images, mainly in the affected bone. In (c), oblique reformatted CT images of the right clavicle show in high detail destruction of the medial third of the bone along with bone expansion and extensive periosteal reaction, as well as mild sclerosis of the cancellous bone��������������������������������������������������������������������������������������������� 174 A 16-year-old male with CRMO and involvement of the left clavicle. Reformatted coronal CT image of the anterior chest wall (a) shows a destructive lesion in the medial third of the left clavicle with adjacent soft-tissue component. In (b), oblique reformatted CT images of the right (upper image) and left (lower image) clavicles display destruction and fragmentation of the medial extremity of the latter, with marked periosteal reaction and soft-tissue swelling. Comparative reformatted axial oblique CT images (c) reveal, in addition to the above described destructive lesion, sclerosis of the cancellous bone and diffuse hyperostosis of the left clavicle, with cortical thickening and narrowing of the medullary canal����������������������������������������������������������������������������������������� 176 A 9-year-old female with CRMO and pelvic lesions. In (a), axial T1-WI and fat sat T2-WI demonstrate small lytic lesions of the cancellous bone, bone marrow edema, and soft-tissue edema adjacent to the right ischiopubic synchondrosis. A supplementary coronal fat sat T2-weighted sequence with increased field-of-view including the whole pelvis (b) was subsequently performed and disclosed multiple sites of bone marrow edema affecting the symphysis pubis, the triradiate cartilages, both ischiopubic synchondroses, the iliac crest apophyses (notably in the left side), and the sacroiliac joints����������������������������� 177 Axial (a) and coronal (b) fat sat T2-WI of the left hip exhibit multifocal involvement of the pelvis in a 10-year-old boy with CRMO. In addition to osteitis, lytic lesions, and soft-tissue edema adjacent to the right ischiopubic synchondrosis, there is also involvement of the left triradiate cartilage, associated with hip effusion and edema of the adjacent obturator internus muscle, mimicking osteomyelitis and septic arthritis������������������������������������������������������������������������� 178 Lateral radiograph (left), sagittal T2-WI (center), and sagittal postgadolinium fat sat T1-WI (right) of the thoracic spine of a 10-year-old male with CRMO. Radiographic findings include collapse and sclerosis of a midthoracic vertebral body (vertebra plana) with no apparent abnormalities of the adjacent vertebrae. On MRI images, in addition to the aforementioned vertebral collapse, there are bone marrow edema in the adjacent vertebrae and infiltration of the prevertebral and posterior epidural soft tissues, all of which show post-contrast enhancement. The contiguous intervertebral discs, however, show no signs of inflammation������������������������������������������������������������������������������������������������������� 179 Involvement of the left costovertebral joint at level T7 in a 9-year-old boy with CRMO. The left images display axial STIR slices showing osteitis in the posterior portion of the corresponding rib and adjacent soft-tissue edema. The right images display transverse and reformatted coronal CT images disclosing predominantly lytic changes of the medullary bone, as well as cortical destruction and mild expansion of the posterior extremity of the rib ����������������������������������������������������������������������� 180

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Fig. 6.18 A 4-year-old female with DIRA. Reformatted sagittal CT images reveal extensive bone destruction and collapse of several upper thoracic vertebral bodies related to long-standing osteitis, with severe disorganization of the spinal architecture. Fusion of the corresponding apophyseal joints was also present (not shown)������������������������������������������������� 181 Fig. 7.1 Female adolescent complaining of painful swelling of her left hallux. (a) Radiographs reveal widening of the mid-diaphysis of the proximal phalanx of the first ray, as well as solid periosteal reaction and premature osteoarthritis of the corresponding metatarsophalangeal joint. There is an ill-defined lucency in the distal diaphysis (arrows), with a central area of increased density. (b) Sagittal T1-WI (left) and STIR images (center and right) demonstrate a subperiosteal OO adjacent to the plantar cortex of the proximal phalanx, with low signal intensity in all sequences in its inner portion related to a calcified nidus. Extensive edema of the bone marrow and of the adjacent soft tissues is evident, as well as metatarsophalangeal arthritis. (c) Coronal gradient-­echo image (upper image), T2-WI (central image), and post-­gadolinium fat sat T1-WI (lower image) corroborate the above described findings and reveal enhancement of the non-mineralized portion of the nidus and of the inflamed tissues������������������������������������������������� 184 Fig. 7.2 An 18-year-old patient complaining of chronic arthritis of the right ankle since age 15. He underwent two biopsies of the calcaneus that were inconclusive. (a) Radiographs reveal marked osteoporosis and premature osteoarthritis of the midfoot and of the hindfoot, with sclerosis of the anterior process of the calcaneus.0 (b) Transverse CT images (upper row) and a sagittal reformatted image (lower row) demonstrate, in addition to the abovementioned findings, the grossly calcified nidus of an OO of the anterior calcaneal process associated with reactive sclerosis and exuberant bone neoformation. (c) Sagittal T1-WI (upper left image) and STIR image (upper right image) demonstrate that the nidus is predominantly hypointense in all imaging sequences, with surrounding edema of the bone marrow and of the adjacent soft tissues. In the lower row, STIR images in the transverse (left) and coronal (right) planes are very helpful to demonstrate the edematous changes and the arthritic component in the ankle, with joint effusion and synovitis����������������������������������������������������������������������������������������� 185 Fig. 7.3 Transverse CT image of the left midfoot demonstrates an OO nidus in the superolateral portion of the cuboid bone, with peripheral hypodensity and a calcified central component ������������������������������������������������� 186 Fig. 7.4 Transverse CT images (upper row), coronal reformatted image (lower row, left), and volume-rendered reconstruction (lower row, right) of the left hip of a 12-year-old male. There is a lucent nidus of OO in the anterior cortex of the femoral neck with a distinctive central calcification, surrounded by sclerosis and associated with cortical thickening. The volume-rendered image shows abnormal widening of the femoral neck, as well as irregularity of the contours of the anterior cortex������������������������������������������������������������������������������������������������������������������� 187 Fig. 7.5 Bone scintigraphy of the same patient as in Fig. 7.3. There is increased uptake in the lateral portion of the left midfoot, which is completely non-specific. In cases like this, other imaging studies should be requested in order to clarify the real nature of the abnormal finding����������������� 188 Fig. 7.6 (a) Radiographs and transverse and coronal reformatted CT images (b) of the left shoulder of a 17-year-old boy. There is a well-­delimited and

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eccentrically located lytic lesion in the anterior portion of the humeral head, surrounded by a thin sclerotic halo and presenting delicate calcifications in the tumor matrix; periosteal reaction is present along the diaphysis of the proximal humerus. (c) Coronal fat sat T2-WI (left images) and T1-WI (upper right image) show predominance of intermediate to low signal intensity in the tumor as well as extensive bone marrow edema, periostitis along the medial cortex of the proximal diaphysis of the humerus, small joint effusion, and edema of the adjacent soft tissues. Coronal post-gadolinium fat sat T1-WI (lower right image) displays enhancement of the lesion itself and of the aforementioned edematous changes������������������������������������������������������������������� 189 Fig. 7.7 CT of the hips of an adolescent with chondroblastoma of the left proximal femur. A coronal reformatted image (upper image) and a transverse section (lower image) demonstrate a well-delimited lytic lesion in the left femoral head, surrounded by a thin sclerotic rim, with delicate foci of calcification in the tumor matrix. In spite of the circumscribed appearance of the lesion, there is extensive cortical discontinuity with dissemination to the joint cavity������������������������������������������� 191 Fig. 7.8 (a) Lateral view of the left knee of an 11-year-old female with joint pain shows irregularity of the posterior cortex of the medial femoral condyle, immediately above the growth plate. (b) Transverse images of a CT-arthrography (upper row) demonstrate that the irregular cortex is adjacent to the origin of the medial gastrocnemius, with subtle subcortical sclerosis. This cortical desmoid is hyperintense on transverse fat sat T2-WI (b, lower row). (c-f) A large bone defect is seen in a similar location in a 13-year-old male, clearly associated with the origin of the medial gastrocnemius, which is more evident on reformatted and volume-rendered CT images ��������������������������������������������������� 192 Fig. 7.9 A 21-month-old female with painful limp, progressive deformity of the right leg, and refusal to walk. Radiographs of the legs (a) demonstrate a lucent lesion extending obliquely downward in the medial cortex of the proximal portion of the right tibia. Varus deformity, cortical thickening, and marked peripheral sclerosis are also present, making this radiographic picture typical of FFD. Transverse CT image at the level of the lesion (b) also shows a well-delimited lytic cortical lesion with prominent perilesional sclerosis and cortical thickening. (c) Coronal reformatted image (left) and volume-rendered reconstruction (right) demonstrate close relation of the lesion to the insertion site of the pes anserinus tendons����������������������������������������������������������������������������������� 195 Fig. 7.10 Oblique radiograph (first image) of the left knee of a young child with DEH showing a partially calcified mass in the medial soft tissues of the joint. Coronal reformatted CT image (second image) and volumerendered reconstruction (third image) reveal that the lesion is eccentrically located in the medial portion of the epiphyseal cartilage of the distal femur, partially cartilaginous and partially ossified. A coronal gradient-echo image (fourth image) is very helpful to display the calcified component of the lesion inside the medial portion of the epiphyseal cartilage of the distal femur, which is abnormally enlarged, leading to valgus deformity of the knee������������������������������������������������������������� 196 Fig. 7.11 Radiographs of the right knee of a skeletally immature patient (a) demonstrate a partially calcified soft-tissue mass in the posteromedial portion of the distal femoral epiphysis, projected over the non-ossified epiphyseal cartilage. MRI performed some months later (b, coronal

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Fig. 7.12

Fig. 7.13

Fig. 7.14

Fig. 7.15

Fig. 7.16

Fig. 7.17

Fig. 7.18

T1-WI [left], fat sat PD-WI [center], and sagittal post-­gadolinium fat sat T1-WI [right]) discloses an epiphyseal mass containing areas of ossification, which are predominantly isointense with the ossified portion of the adjacent secondary ossification center. There is focal bulging of the epiphyseal cartilage, without abnormal enhancement on post-contrast images. These findings are typical for DEH��������������������������������� 196 A 3-year-old male with DEH of the right tibial tubercle. (a) Radiographs reveal increased size of the tibial tubercle, with continuity between the cortical and cancellous bone of the mass and those of the tibia. (b) Transverse sections (upper images), sagittal reformatted image (lower left image), and volume-rendered reconstruction (lower right image) of a contrast-enhanced CT scan corroborate the radiographic findings, demonstrating a cartilaginous cap of normal appearance and absence of periosteal reaction, cortical discontinuity, any soft-tissue mass, or abnormal post-contrast enhancement��������������������������� 198 Conventional arthrogram of the right shoulder. The contrast agent inside the joint cavity delineates an intra-articular mass with irregular and lobulated contours related to villous synovial thickening in this patient with PVNS. Even though this image is very illustrative of the macroscopic appearance of the synovial proliferation, its value is essentially pictorial and historical, as conventional arthrograms are no longer used for this purpose������������������������������������������������������������������������������� 199 Radiographs of the left knee of a patient with PVNS. There is a lobulated suprapatellar mass in the soft tissues of the suprapatellar pouch, whose density is higher than that of the adjacent soft-tissue planes. Pressure erosions in the anterior cortex of the distal femur are also present, well-defined, and presenting sclerotic borders, which are indicative of long evolution and low aggressiveness ����������������������������������������� 200 Planigraphy of the right hip of a patient with PVNS disclosing an extensive lucent lesion in the anterolateral cortex of the femoral neck, surrounded by a sclerotic rim (pressure erosion)����������������������������������������������� 200 MRI of the left knee of a female adolescent with PVNS (3 years of evolution). Coronal fat sat T2-WI (a), sagittal T1-WI (b), sagittal gradient-echo image (c), and transverse gradient-echo image (d) disclose nodular thickening of the synovium, which presents a villous appearance and displays low signal intensity in all sequences, mostly gradient-echo images, related to hemosiderin buildup. These findings are more prominent in the suprapatellar pouch, posterior to the cruciate ligaments and in the infrapatellar fat pad����������������������������������������������������������� 201 Transverse fat sat PD-WI (a and b), sagittal T1-WI (c), and coronal fat sat PD-WI (d) of the right knee of an adolescent with long-­standing PVNS. In addition to hypointense synovial thickening and intraarticular buildup of hemosiderin, there is a destructive arthropathy similar to that found in hemophilia, with diffuse cartilaginous thinning, cortical erosions, and osteochondral lesions. Overgrowth of the medial femoral condyle is also evident��������������������������������������������������������������������������� 202 Nodular synovitis of the left knee in a 15-year-old patient. There is a well-delimited mass of intermediate signal intensity on T1-WI (left) and T2-WI (center) in the Hoffa fat pad, with high signal intensity on fat sat PD-WI (left). Magnetic susceptibility artifacts can be seen inside the lesion. Nevertheless, hemosiderin impregnation is less intense than that usually present in the diffuse form of PVNS����������������������������������������������� 203

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Fig. 7.19 Radiographs of the index finger of a 15-year-old patient with GCTTS revealing nodular soft-tissue swelling that is volar and medial relative to the middle phalanx, with subtle remodeling of the adjacent cortex��������������� 204 Fig. 7.20 GCTTS of the flexor tendons of the third toe in the right foot of a 10-year-old male. (a) shows sagittal STIR images (left) and T2-WI in the sagittal and coronal planes (right), while (b) displays pre-contrast coronal T1-WI (left) and post-contrast sagittal and coronal T1-WI (right). The mass is heterogeneous and contains multiple septa, with low to intermediate signal intensity on T1-WI and T2-WI and high signal intensity on STIR images. The tumor envelops the flexor tendons of the third toe and displaces the flexor tendons of the second and fourth toes. Heterogeneous enhancement is seen on postgadolinium images ��������������������������������������������������������������������������������������������� 205 Fig. 7.21 Bilateral lipoma arborescens of the knees of a 12-year-old male. Coronal T1-WI and fat sat T2-WI of the right (upper row) and left (lower row) knees disclose large villous masses with signal intensity similar to that of the subcutaneous fat largely occupying the joint cavities. Bilateral arthritis is also present, as well as a large joint effusion in the left knee��������������������������������������������������������������������������������������� 206 Fig. 7.22 Lipoma arborescens of the right knee. There is an abnormal structure of villous appearance in the suprapatellar pouch and in the Hoffa fat pad, whose signal intensity is similar to that of the subcutaneous fat on T1-WI (left) and on T2-WI (center), showing signal drop on fat sat T2-WI (right). Joint effusion is also evident������������������������������������������������������� 207 Fig. 7.23 PSO of the left hip joint in a skeletally immature patient. Anteroposterior radiograph (upper image) discloses several mineralized nodules medial to the femoral neck, as well as osteoporosis of the proximal femur. The lower image is a radiograph of the surgical specimen (post-synovectomy) revealing that most nodules have a rim of cortical bone and an inner core of cancellous bone. Even though there are at least four dominant nodules, most of the remaining are small and relatively uniform in size ������������������������������������������������������������� 207 Fig. 7.24 Reformatted sagittal images of a non-enhanced CT of the knee highlighting features of a synovial hemangioma in a young patient. There is an intra-articular mass (solid arrows) with lobulated contours and heterogeneous appearance, predominantly of soft-tissue density; the mass is surrounded by fat, and fat strands can be seen throughout the lesion. A calcified phlebolith is clearly identified (dashed arrow) ��������������� 208 Fig. 7.25 Sagittal fat sat T2-WI (first and second images), post-­gadolinium fat sat T1-WI (third image), and subtracted post-­gadolinium fat sat T1-WI (fourth image) of the right knee of a 3-year-old girl. There is a SVM of the diffuse type infiltrating the soft tissues of the infrapatellar and suprapatellar compartments, characterized by multiple serpentine structures of high signal intensity on fat sat T2-WI that exhibit postcontrast enhancement, more evident after digital subtraction. As the patient is a young child, there are no signs of arthropathy��������������������������������� 208 Fig. 7.26 Synovial hemangioma of the medial recess of the suprapatellar pouch. The mass is composed of serpiginous vessels that show low signal intensity on T1-WI (upper left image), high signal intensity on STIR (upper right image), and marked enhancement on post-­gadolinium fat sat T1-WI (lower left image). Gradient-echo image (lower right image) is useful to demonstrate low signal intensity in the joint surfaces and in

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the infrapatellar fat pad, related to hemosiderin deposition due to recurrent hemarthroses��������������������������������������������������������������������������������������� 209 Fig. 7.27 Imaging studies demonstrating the evolution of the arthropathy in a patient with synovial hemangioma. (a) The images in the upper row (coronal T1-WI [left] and fat sat T2-WI [right]) reveal a large venous malformation with intra-articular and extra-articular components, which presents intermediate signal intensity on T1-WI and is hyperintense on T2-WI, involving the lateral portions of the distal thigh, knee, and proximal leg. Osteoarthropathy is already present, with thinning of the articular cartilages, irregularity of the joint surfaces, and subtle edema of the subchondral bone marrow. The images in the lower row, obtained 6 months later (after percutaneous treatment), disclose marked decrease of the size of the malformation. However, there is worsening of the osteoarthropathy, with progression of the aforementioned findings and development of significant muscle atrophy. (b) Post-gadolinium fat sat T1-WI acquired prior to treatment demonstrate marked enhancement of the anomalous vascular structures, highlighting the usefulness of contrast-enhanced MRI for accurate staging of SVM������������������������������������������������������������������������������������� 210 Fig. 8.1 Radiographs of the right hip of a child with LCPD show diffuse sclerosis and reduced height of the femoral epiphysis, as well as a subchondral fracture, more evident on the lateral view (right image). Widening of the joint space is also present��������������������������������������������������������� 214 Fig. 8.2 Lateral view of the left hip (a) of a patient with LCPD displaying reduced height and increased density of the femoral epiphysis and a crescent-shaped subcortical lucency (subchondral fracture). Transverse CT image (b) of the same patient demonstrates gas in the fracture site and epiphyseal sclerosis������������������������������������������������������������������������������������� 214 Fig. 8.3 Marked epiphyseal sclerosis is seen in this anteroposterior view of the left hip, with flattening of the articular surface and collapse of the lateral two-thirds of the ossified portion of the femoral head. There is also mild lateral subluxation of this epiphysis��������������������������������������������������� 215 Fig. 8.4 Metaphyseal reaction in the right hip of a patient with LCPD. There are multiple well-delimited and confluent lucencies adjacent to the physis, with broadening of the femoral neck. The femoral head is denser than normal, with focal lucencies permeating the sclerotic bone������������������������������� 215 Fig. 8.5 The left proximal femoral epiphysis shows decreased density and size when compared with the contralateral one in this radiograph, findings related to LCPD. Metaphyseal reaction is present, as well as slight widening of the joint space��������������������������������������������������������������������������������� 215 Fig. 8.6 In this patient with LCPD, the left proximal femoral epiphysis is flattened and fragmented due to ischemia, with a centrally located sequestrum. There is remodeling of the femoral neck, which is broadened and shortened, in addition to obvious widening of the joint space and extrusion of the lateral portion of the femoral epiphysis������������������� 216 Fig. 8.7 Radiographs of the hips in a patient with bilateral LCPD displaying fragmentation and reduced size of the left proximal femoral epiphysis, with ipsilateral metaphyseal reaction and broadening of the femoral neck. The right femoral head is also flattened, sclerotic and irregular, and metaphyseal reaction and femoral remodeling are also present, but the findings are less prominent than in the left hip��������������������������������������������� 216 Fig. 8.8 Radiographs of both hips (a and b) demonstrate flattening and fragmentation of the right proximal femoral epiphysis, affecting mainly

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Fig. 8.11

Fig. 8.12

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its lateral two-thirds, with associated metaphyseal reaction. There is partial extrusion of the right femoral head and remodeling of the acetabular cavity, which is widened and shallow. The right femoral neck is shortened and broadened ����������������������������������������������������������������������� 216 In (a), radiographs of the left hip of a child with LCPD display flattening and fragmentation of the proximal femoral epiphysis affecting mainly its lateral third, with a wavy, M-shaped growth plate. The femoral neck is broadened and shortened, with sclerosis of the medial cortex representing a response to anomalous overload. In (b), radiographs obtained 9 months later demonstrate coalescence of bone fragments, with reossification of the lateral pillar and partial restoration of the convexity of the articular surface. Nonetheless, the epiphysis is deformed and partially extruded������������������������������������������������������������������������� 217 Late-stage sequelae of LCPD in a young adult. Radiograph (upper left image), volume-rendered reconstruction (upper right image), transverse CT section (lower left image), and reformatted coronal image (lower right image) demonstrate morphologic abnormalities of the left femoral head (flattening and loss of spherical shape, lateral subluxation, and joint incongruity) and femoral neck (shortening and broadening)��������������������� 218 Radiographs of the pelvis (a) and of the knees (b) of a child with multiple epiphyseal dysplasia. Radiographic findings in the hips resemble those found during the fragmentation phase of LCPD. However, these findings are bilateral and symmetric, and morphologic epiphyseal abnormalities are also found in the distal femora and proximal tibiae, indicating their dysplastic nature��������������������������� 219 Schematic representation of the three pillars of the proximal femoral epiphysis, with the lateral pillar highlighted. Lack of involvement of this pillar in the early fragmentation phase of LCPD corresponds to Herring type A. When this pillar is involved and there is less than 50% of reduction of its height, the patient is Herring type B. In patients Herring type C, more than 50% of this pillar is collapsed��������������������������������� 219 T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) of the right hip of a 10-year-old female with LCPD. The first MRI study (upper row) revealed joint effusion, synovitis, and absent post-contrast enhancement of the whole proximal femoral epiphysis, even in the absence of bone marrow edema; there is no deformity of the femoral head, and the labrum is normal. MRI performed 14 months later (lower row) discloses epiphyseal fragmentation and flattening associated with bone marrow edema and heterogeneous post-contrast enhancement of the ischemic bone; there is also joint incongruity, with extrusion of the femoral head and horizontalization of the labrum, as well as bone marrow edema, widening of the femoral neck and cartilaginous thickening (mostly medial). Joint effusion and synovitis are present on follow-up images as well������������������������������������������������������������� 220 MRI of the hips of a child with right-sided LCPD. The right proximal femoral epiphysis presents low signal intensity if compared to the contralateral one in a coronal fat sat T1-WI (upper image) and increased signal intensity on a coronal T2-WI (lower image), findings compatible with bone marrow edema. Reduced epiphyseal size, bone fragmentation, and epiphyseal collapse are absent, but decreased epiphyseal perfusion was present in post-contrast images (not shown)������������� 221 Coronal T1-WI (left) and sagittal T2-WI (right) of the left hip of a child with LCPD reveal low signal intensity in both sequences in the

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Fig. 8.21

Fig. 8.22

Fig. 8.23

subchondral bone of the weight-bearing zone of the femoral epiphysis, which is reduced in size ������������������������������������������������������������������������������������� 221 Coronal T1-WI (a) and sagittal gradient-echo image (b) demonstrate reduced size and abnormal shape of the left proximal femoral epiphysis, with low signal intensity of the epiphyseal bone marrow in both sequences. There is thickening of the femoral cartilage, more evident in (a)������������������������������������������������������������������������������������������������������� 222 MRI of the right hip of a 9-year-old male with LCPD. T1-WI (a and b, left images) and fat sat T2-WI (a and b, right images) in the coronal and sagittal planes demonstrate bone marrow edema in the lateral pillar of the proximal femoral epiphysis and low signal intensity in both sequences in the subchondral bone of its central portion, the latter being indicative of sclerosis. Joint effusion is also present, as well as bone marrow edema in the femoral neck ����������������������������������������������������������� 223 Coronal T1-WI (a), fat sat T2-WI (b), and post-gadolinium fat sat T1-WI (c) of the right hip of a 4-year-old male with LCPD. The proximal femoral epiphysis is irregular, presenting reduced size and markedly decreased signal intensity in all sequences. Joint effusion, bone marrow edema in the femoral neck, and metaphyseal reaction are also present. Post-contrast images demonstrate absent enhancement in the ischemic epiphysis, while the edematous bone, the inflamed synovium, and the metaphyseal “cysts” display obvious enhancement������������� 224 MRI of the hips of a young child with right-sided LCPD (coronal T1-WI [upper image], gradient-echo image [central image], and post-contrast fat sat T1-WI [lower image]). The affected epiphysis is reduced in size and presents diminished perfusion, with low signal intensity of the subchondral bone and ipsilateral cartilaginous thickening����������������������������������������������������������������������������������������������������������� 225 MRI of an 8-year-old male with right-sided LCPD (coronal fat sat T2-WI [left], T1-WI [center], and post-gadolinium fat sat T1-WI [right]). There is ischemic involvement of the proximal femoral epiphysis, more evident in the central and medial pillars, characterized by a geographic area of heterogeneous signal intensity on T2-WI and low signal intensity on T1-WI. Mildly abnormal signal intensity is also seen in the lateral pillar. The post-gadolinium image shows areas of intense enhancement permeating the ischemic region and the lateral pillar representing ongoing bone repair and revascularization. The femoral neck is shortened and broadened����������������������������������������������������������� 226 MRI of the left hip of an 11-year-old female with LCPD. T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) show focal depression of the osseous surface of the femoral epiphysis at the transition of the medial and central pillars, sparing the lateral pillar. Increased signal intensity on T2-WI and enhancement of the bone marrow in the central and lateral pillars can be seen, which are indicative of revascularization. Joint congruity is preserved, with adequate head containment��������������������������������������������������������������������������������� 226 LCPD of the left hip, late fragmentation phase. Coronal T1-WI (upper image) and post-gadolinium fat sat T1-WI (lower image) demonstrate extensive epiphyseal collapse, with fragmentation, heterogeneous enhancement of the necrotic areas, and remodeling of the metaphysis and of the acetabulum. A large joint effusion is also present����������������������������� 227 MRI of a young adult with late-stage sequelae of right-sided LCPD. T1-WI in the coronal (upper images) and transverse (lower

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Fig. 8.25

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Fig. 8.27

Fig. 9.1

Fig. 9.2

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images) planes demonstrate complete restoration of the normal signal intensity of the femoral head. Nonetheless, the epiphysis is deformed and flattened, with acetabular remodeling, joint incongruity, and lateral subluxation��������������������������������������������������������������������������������������������������������� 228 A 47-year-old patient with late-stage sequelae of right-sided LCPD. Coronal T1-WI (a) and fat sat T2-WI (b) and sagittal fat sat T2-WI (c) reveal a markedly deformed femoral head and severe secondary osteoarthritis of the hip. A large degenerative subchondral cyst can be seen in the acetabular roof, disrupting the cortex of the iliac bone and presenting intrapelvic extension ��������������������������������������������������������� 229 CT of the hips of a 3-year-old male. Coronal reformatted images show sclerosis, fragmentation, and reduced size of the ossified portion of the left proximal femoral epiphysis. Even though the diagnosis of LCPD in early fragmentation stage is quite obvious, CT is unable to detect bone marrow edema or to assess the pattern of revascularization, being also limited in the evaluation of the soft tissues. (Courtesy of Dr. Pablo Coimbra, MD, Uniclinic Diagnóstico por Imagem – UDI and Clínica Trajano Almeida, Fortaleza, Brazil)������������������������������������������������������������������� 230 Reformatted coronal CT images of the hips of a 5-year-old female with right-sided LCPD. In addition to advanced epiphyseal collapse, with sclerosis and fragmentation, acetabular remodeling and widening of the femoral neck can also be seen in the affected hip����������������������������������������������� 231 Oblique reformatted CT images of both hips (a) and volume-­rendered reconstruction (b) of a 62-year-old patient with late-stage sequelae of right-sided LCPD. There is loss of the spherical shape of the right femoral head, which presents a “mushroom” appearance (left image in a), in addition to broadening and shortening of the femoral neck. Acetabular remodeling and secondary osteoarthritis are also evident in the right hip��������������������������������������������������������������������������������������������������������� 232 (a) Coronal T1-WI (left) and fat sat T2-WI (right) of the left hip of a child with SCD discloses diffuse alteration of the signal intensity of the bone marrow, which is predominantly hypointense on T1-WI and hyperintense on fat sat T2-WI, representing hyperplasia of the red marrow related to chronic anemia. Similar changes can be seen in 9.1b in the right knee of a 16-year-old male with SCD (coronal T1-WI [left] and sagittal PD-WI [right]), with widespread replacement of the fatty marrow by a comparatively hypointense hematopoietic marrow in both sequences; residual fatty marrow can be seen in the innermost portion of the epiphyses (mostly in the tibia) and, more extensively, in the patella����������������������������������������������������������������������������������������������������������������� 236 Radiographic abnormalities related to marrow hyperplasia in SCD. (a) There is enlargement of the tubular bones of the right hand and of the distal portions of the radius and ulna, with coarse appearance of the trabeculae. (b) The ribs are widened due to enlargement of the medullary cavities, with irregular periosteal reaction in several of them����������� 237 Lateral radiograph of the skull of a 7-year-old child with SCD. Widening of the diploic space is evident, with prominence of bone trabeculae, thickening of the inner table, and thinning of the outer table. The occipital squama is spared����������������������������������������������������������������� 237 Radiographic abnormalities of the spine of a child with SCD. There is diffuse osteoporosis and coarsening of the trabeculae. Several vertebrae present reduced height and a biconcave appearance, notably in the

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thoracic spine, related to hyperplasia of the red marrow. “H-shaped” vertebrae are also present in the lumbar spine ��������������������������������������������������� 238 Fig. 9.5 Lateral view of the lumbar spine of a child with SCD revealing diffuse osteoporosis and reduced height of the vertebral bodies of L2 and L5, with subtle posterior wedging of the latter��������������������������������������������������������� 239 Fig. 9.6 Radiograph of the left ankle of a 15-year-old boy with SCD and tibiotalar slant. Even though this is a classic radiographic finding in SCD, other conditions, such as hemophilia and juvenile idiopathic arthritis, may present a similar appearance��������������������������������������������������������� 239 Fig. 9.7 Lateral view of the thoracolumbar spine of a child with SCD showing the typical “H-shaped” vertebrae. There are focal depressions of the affected endplates, acutely delimited, whose appearance differs from that of the biconcave vertebrae weakened by hyperplasia of the red marrow ��������������������������������������������������������������������������������������������������������������� 239 Fig. 9.8 (a) Radiograph of hands and wrists of a child with sickle cell dactylitis demonstrates soft-tissue swelling and irregular periosteal reaction along the left metacarpals (from the second to the fifth) and in the right proximal phalanges of the fourth and fifth digits. There is also symmetric, diffuse, and bilateral widening of the phalanges, which show prominent bone trabeculae and solid periosteal reaction in some diaphyses. (b) Radiograph of the right hand of an 11-month-old male with acute dactylitis shows periosteal reaction in several metacarpals and cortical moth-eaten lesions, mainly in the third one; mottled osteoporosis is also present��������������������������������������������������������������������������������� 240 Fig. 9.9 There is diaphyseal widening of the first metacarpal (which displays a cylindrical appearance) in this child with SCD due to expansion of the medullary cavity. Bone trabeculae are prominent and coarse, with a striated pattern. Solid periosteal reaction is seen in the proximal phalanges, mainly in the fourth finger ��������������������������������������������������������������� 241 Fig. 9.10 (a) Anteroposterior view of the right femur of a male adolescent with SCD discloses a bone infarct as an extensive lucency with lobulated borders in the medullary cavity of the distal diaphysis, without associated calcifications; the distal portion of the lesion is reasonably well-delimited, while the proximal portion is ill-defined. (b) Radiographs of the right leg of a 17-year-old male with SCD and a painful limb reveal an extensive and ill-defined lucency in the distal tibial diaphysis, with loss of the trabeculae, findings related to a bone infarct ����������������������������������������������������������������������������������������������������������������� 241 Fig. 9.11 Radiographs of the right leg (a) and of the left upper limb (b) of a child with SCD (18-month-old) reveal diffuse osteoporosis, areas of bone sclerosis, and solid periosteal reaction in the long bones, related to bone infarcts. (c) Radiographs of the left knee of a 16-year-old female with SCD disclose well-demarcated serpiginous areas of sclerosis in the medullary bone of the diaphyses of the distal femur and proximal tibia, typical of chronic bone infarcts����������������������������������������������������������������� 242 Fig. 9.12 Anteroposterior and lateral views of the right leg of the same child obtained 3 years apart demonstrate the low sensitivity of this method for the assessment of acute infarcts in SCD. Radiographs obtained during an acute painful crisis (left) do not disclose any abnormal findings, except for a non-ossifying fibroma in the distal tibia. On follow-up (right), there are extensive sclerotic areas in the medullary cavity of the proximal tibia, with periosteal reaction and cortical

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thickening along the tibia and the fibula, findings related to bone infarcts of chronic evolution������������������������������������������������������������������������������� 243 (a, b) Radiographs of the pelvis of a 13-year-old female with SCD and bilateral avascular necrosis of the femoral heads disclose heterogeneous sclerosis of the medullary bone of the proximal femoral epiphyses and flattening of the corresponding articular surfaces, more important in the right hip; there is also a subchondral fracture and partial collapse of the right femoral head. (c) Pelvic radiograph of a 16-year-old female with SCD shows diffuse sclerosis of the medullary bone of the iliac bones and of the femora, with a “bone-within-bone” appearance in the proximal femoral diaphyses. Even though it is clear that there are multiple chronic bone infarcts, this imaging method is insensitive to detect acute ischemia. Coronal T1-WI (d), fat sat T2-WI (e), and post-gadolinium fat sat T1-WI (f) of the hips of the same patient reveal recent bone infarcts in the femoral diaphyses, with hyperintense areas on T1-WI and T2-WI and mild post-contrast enhancement. There is also extensive avascular necrosis of the left femoral head, with enhancement of the lateral pillar. A non-enhancing, serpiginous area of low signal intensity in all sequences in the right femoral head represents an old infarct, with bone sclerosis������������������������������� 244 (a, b) Radiographs of two distinct patients demonstrate linear areas of sclerosis in the medullary cavities of the proximal femora, adjacent to the cortical bone (“bone-within-bone” appearance). In SCD, this finding – that may be found in many other conditions – is related to bone infarcts������������������������������������������������������������������������������������������������������� 245 An 8-year-old child with SCD and an acute painful crisis in the right thigh. (a) Coronal fat sat T1-WI before (left) and after (right) administration of intravenous gadolinium reveal an extensive area of increased signal intensity in the medullary cavity of the femur, representing hemoglobin degradation products related to a bone infarct, with post-contrast enhancement of the ischemic bone and surrounding soft tissues. On transverse post-gadolinium fat sat T1-WI of the thighs obtained 1 month later (b), the bone infarct of the right femur displays predominantly peripheral enhancement, while there is also diaphyseal osteomyelitis in the contralateral femur, with a subperiosteal abscess appearing as an encapsulated fluid collection that shows peripheral enhancement; diffuse and intense post-contrast enhancement of the adjacent soft tissues is evident as well. Diaphyseal osteomyelitis of the left tibia was also present (not shown)��������������������������������������������������������������� 245 (a) Sagittal fat sat T2-WI (left) and fat sat T1-WI before (center) and after (right) administration of intravenous gadolinium demonstrate a large geographic area of abnormal signal intensity in the right femoral diaphysis of a 13-year-old female with SCD, predominantly hyperintense both on T1-WI and T2-WI and exhibiting heterogeneous post-contrast enhancement, mostly peripheral, findings related to a bone infarct. (b) T1-WI (left), fat sat T2-WI (center), and post-­ gadolinium fat sat T1-WI (right) of the right hip of a 15-year-old female with SCD disclose geographic areas of abnormal signal intensity in the apophysis of the greater trochanter and in the supraacetabular iliac bone, as well as in the femoral epiphysis and in the medullary cavity of the proximal diaphysis. The former is a heterogeneous lesion with fat in the central portion surrounded by a thin rim of low signal intensity in all sequences, while the latter three

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Fig. 9.17

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Fig. 9.20

Fig. 9.21

Fig. 9.22

are ill-defined, presenting low signal intensity on T1-WI and high signal intensity on fat sat T2-WI; predominantly peripheral postgadolinium enhancement is seen in all lesions. These are bone infarcts in different stages: the apophyseal lesion is older, while the iliac, epiphyseal, and diaphyseal ones show evidence of recent ischemia ����������������� 246 (a) Symmetric and bilateral areas of sclerosis are seen in the medullary bone of the proximal humeral epiphyses, also present in the proximal metadiaphyses of both humeri, more evident in the right shoulder, representing chronic bone infarcts and/or avascular necrosis. (b) Avascular necrosis of the right femoral head can be seen in a child with SCD, in whom the femoral epiphysis presents heterogeneously high density, with flattening and irregularity of the epiphyseal surface (the latter two more evident in the lateral view) ������������������������������������������������������� 247 Sagittal fat sat T2-WI (left), T1-WI (center), and subtracted postgadolinium fat sat T1-WI (right) of a 16-year-old male with SCD and a hemorrhagic infarct of the fibular head. The first and the second images reveal diffuse high signal intensity in the proximal fibular epiphysis due to the presence of hemoglobin degradation products, while the third image discloses absent perfusion of the ischemic epiphysis. There is also extensive replacement of the fatty marrow by hematopoietic marrow ��������������������������������������������������������������������������������������������������������������� 248 Subperiosteal bleeding in a 2-month-old male with SCD and pain upon mobilization of the left lower limb. Radiograph of the left thigh (a) demonstrates solid periosteal reaction along the femoral diaphysis. Sagittal and transverse fat sat T2-WI of the same patient (b, upper images) disclose a hyperintense subperiosteal collection, which is hypointense on T1-WI (lower left image) and presents minimal post-­gadolinium enhancement (lower right image); the adjacent bone is normal����������������������������������������������������������������������������������������������������������������� 249 (a) Radiographs of an 8-year-old child with SCD and signs of infection in the left leg demonstrate chronic osteomyelitis in the distal diaphysis of the tibia, with extensive bone destruction, layered periosteal reaction, and a posterolateral cloaca in the lower portion of the lesion. (b) Radiographs of the right femur of a 5-year-old child with SCD and chronic osteomyelitis reveal (left image) an extensive lucency in the medullary bone of the diaphysis, with sclerosis of the surrounding bone and discontinuous periosteal reaction, as well as mineralized nodules in the posterior soft tissues of the thigh possibly representing osteoporotic sequestra contained by the periosteum. Lateral radiograph of the same site taken 11 months later (right image) reveals cavitation in the posterior portion of the femoral diaphysis surrounded by a sclerotic rim and containing a large bone fragment. Periosteal reaction became solid and continuous ��������������������������������������������������������������������������������������������������� 250 Extensive destruction of the anterior portion of the vertebral body of L2 in a 16-year-old female with SCD and spinal infection. There is also destruction of the anteroinferior corner of L1 and of the anterosuperior corner of L3, as well as narrowing of the corresponding disc spaces. SCD-related findings are present, with diffuse osteoporosis, “fish mouth” deformities and H-shaped vertebrae����������������������� 251 Multiple vertebral infarcts and spondylodiscitis in an 8-year-­old child with SCD. Sagittal T2-WI (first image) and STIR image (second image) reveal areas of increased signal intensity in several vertebral bodies (more prominent from T6 to T10 and in L3) related to bone

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Fig. 9.24

Fig. 9.25

Fig. 9.26

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infarcts, with normal appearance of the adjacent intervertebral disks. In L4–L5, however, there is reduction of the disc height and heterogeneous signal intensity of the disc itself, as well as destruction of the adjacent endplates and bone marrow edema. An intraosseous abscess is seen in the anterior portion of L5, with cortical discontinuity and extension to the prevertebral space, contained by the anterior longitudinal ligament. An epidural phlegmon is also present, extending from L4 to S1. Post-gadolinium T1-WI in the sagittal (third image) and transverse (fourth image) planes disclose peripheral enhancement in the abovementioned abscess and diffuse enhancement in the inflamed epidural tissue, as well as mild enhancement of the bone marrow of the ischemic vertebral bodies����������������������������������������������������������������������������������� 251 Septic arthritis of the left hip in a child with SCD. Pelvic radiograph (left) demonstrates subtle widening of the joint space of the left hip, related to purulent effusion and capsular distension, and reduced size of the ossified portion of the ipsilateral epiphysis. Radiograph of the affected hip taken 5 months later (right) reveals diffuse osteoporosis of the proximal femur, narrowing of the uppermost portion of joint space (an indirect indicator of cartilaginous damage) and widening of its medial portion, without significant bone destruction. The relatively slow progression of the radiographic findings is suggestive of lowvirulence infection, given that classic pyogenic arthritis is a rapidly destructive process ��������������������������������������������������������������������������������������������� 252 Transverse CT images of the right shoulder of a child with SCD (upper images and lower left image). There is heterogeneous sclerosis of the medullary bone of the proximal humerus and of the scapula related to chronic bone infarcts, in addition to a large joint effusion and peripheral erosions of the glenoid rim related to septic arthritis. Transverse image of the left shoulder (lower right image) displays purulent effusion in this joint too����������������������������������������������������������������������� 252 A 13-year-old male with beta-thalassemia and exuberant extramedullary hematopoiesis. Sagittal T1-WI (a) and T2-WI (b) and transverse post-gadolinium T1-WI (c) of the thoracic spine demonstrate persistence of red marrow in all vertebral bodies, some of which are mildly enlarged. Expansion of the medullary cavity of the ribs is also present, bilaterally (c). Extramedullary hematopoiesis appears as paraspinal masses and multiple coalescent nodules in the posterior epidural space, also present along the inner cortices of the ribs, presenting signal intensity slightly higher than that of the red marrow and mild post-­gadolinium enhancement. The epidural component causes severe compression of the spinal cord, mostly from T5 to T8. (Courtesy of Dr. Aline Magnago, MD, Bioscan Diagnóstico por Imagem, Vitória, Brazil)������������������������������������������������������������������������������� 254 (a) Radiographs of the left knee of an 8-year-old hemophiliac patient show epiphyseal osteoporosis and overgrowth of the medial femoral condyle, as well as a high-density effusion in the suprapatellar pouch and in the popliteal fossa. (b) There is advanced hemophilic osteoarthropathy in the left knee of a 13-year-old patient characterized by marked osteoporosis, joint space narrowing, erosions of the articular surfaces, epiphyseal overgrowth, and squaring of the inferior margin of the patella; there is also prominence of the periarticular soft tissues, which present high density related to iron deposition ��������������������������������������� 255

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Fig. 9.27 Radiographic evolution of hemophilic arthropathy of the right elbow. (a) Radiographs of the right elbow taken when the patient was 13 years old show regional osteoporosis, early closure of the growth plates, destructive arthropathy, and remodeling of the articular fossae and incisurae. (b) Radiographs of the same elbow taken at age 18 demonstrate advanced osteoarthritis and deformity of the joint surfaces, with excessive growth of the proximal radius and altered joint alignment leading to marked remodeling of the radial fossa of distal humerus��������������������������������������������������������������������������������������������������������������� 256 Fig. 9.28 (a) Transverse gradient-echo image (upper left image) and coronal fat sat T2-WI (remaining images) of the left knee of an 11-year-­old hemophiliac patient demonstrate a small joint effusion, synovial thickening, and chondral and/or osteochondral lesions, mainly in the lateral femoral condyle, with bone marrow edema and erosive changes of the subchondral bone. The first image demonstrates mild hemosiderin impregnation – seen in the joint capsule, in the thickened synovium, and inside the erosion anteriorly located in the lateral femoral condyle – as areas of low signal intensity; meniscal hypoplasia is also present, mostly medial. (b) Coronal T1-WI and fat sat T2-WI of the left knee of a 12-year-old hemophiliac patient disclose marked thinning of the articular cartilages and subchondral cysts, the latter more evident in the articular surfaces of the lateral compartment, surrounded by bone marrow edema; mild hemosiderin impregnation of the articular surfaces and of the synovium is also present, as well as meniscal hypoplasia, notably in the lateral compartment����������������������������������� 257 Fig. 9.29 (a) Coronal T1-WI (left), fat sat T2-WI (center), and gradient-­echo images (right) of the left shoulder of a 12-year-old hemophiliac patient disclose extensive intra-articular hemosiderin deposition, more evident on gradient-echo images, as well as marked bicipital tenosynovitis; nevertheless, the articular cartilages are preserved, and there is no structural joint damage. (b) Transverse (upper row) and coronal (lower row) gradient-echo images of the left knee of an 8-year-­old hemophiliac patient reveal more prominent synovitis and hemosiderin impregnation if compared to those seen in the patient of figure (a), as well as irregular cartilaginous contours and meniscal hypoplasia. (c) Coronal T1-WI (left) and fat sat T2-WI (right) of the left knee of a 13-year-old hemophiliac show extensive osteoarthropathy, with marked cartilaginous destruction, irregularity of the subchondral bone, and subchondral cysts along the joint surfaces, as well as prominent intra-­articular hemosiderin impregnation����������������������������������������������������������� 259 Fig. 9.30 MRI of the right elbow of the same patient as in Fig. 9.27, sagittal T1-WI (a), fat sat T2-WI (b), post-gadolinium fat sat T1-WI (c), and gradient-echo image (d). In addition to the deformities previously described on radiographs, MRI shows joint effusion of intermediate signal intensity on T1-WI and high signal intensity on T2-WI (subacute hemarthrosis) and subchondral bone marrow edema and erosions (which enhance on post-contrast images). Markedly heterogeneous synovial thickening is also present, exhibiting post-gadolinium enhancement and low signal intensity on gradient-echo images (hemosiderin impregnation)������������������������������������������������������������������������������� 262 Fig. 9.31 Advanced hemophilic arthropathy in the left ankle of a 17-year-old patient. Sagittal reformatted CT images (a and b) demonstrate severe tibiotalar osteoarthritis, with large marginal osteophytes, marked

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Fig. 9.32

Fig. 9.33

Fig. 9.34

Fig. 9.35 Fig. 9.36

Fig. 10.1

Fig. 10.2

List of Figures

narrowing of the joint space, and multiple subchondral cysts (the hallmark of hemophilic arthropathy). Sagittal fat sat T2-WI (c) and T1-WI (d) show destruction of the articular cartilages, with subchondral cysts and extensive bone marrow edema, as well as hemosiderin impregnation in the anterior recess of the articular capsule, which is hypointense in all sequences ������������������������������������������������� 263 MRI of the ankles of a 13-year-old male with bilateral hemophilic arthropathy. (a) Images obtained in several spatial planes with different sequences reveal destructive arthropathy of the left ankle, with joint effusion, marked synovitis, osteochondral lesions in the talar dome, and extensive hemosiderin impregnation, the latter being more evident in the gradient-echo sequence (lower left image). (b) Post-­gadolinium T1-WI of the right ankle demonstrates enhancement of the thickened synovium, of the edematous bone marrow, and of the subchondral cysts. Arthropathy is more advanced in the right ankle, with multiple and coalescent subchondral cysts (some of them with mixed content) and secondary osteoarthritis������������������������������������������������������������������������������� 264 A 7-year-old male with hemophilic arthropathy of the left ankle. Coronal fat sat T2-WI display a subchondral cyst in the medial convexity of the talar dome surrounded by a rim of low signal intensity and extensive bone marrow edema. Mild tibiotalar slant is also present����������� 265 Oblique radiographs of the feet of a hemophiliac patient with palpable masses in both heels caused by hemophilic pseudotumors. There is soft-tissue swelling in the hindfeet (notably in the left extremity) and diffuse osteoporosis. Expansile, multiloculated bone lesions are seen in the right cuboid bone and in the left calcaneus, the latter being larger, with ill-defined cortical edges. Coarse trabecular pattern is present in the anterior portion of the right talus, as well as a complete pathologic fracture in the ipsilateral calcaneus. Expansion of the medullary cavities of the diaphyses of the first and of the fourth metatarsals and cortical thinning are also evident in the right foot. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)��������������������������������������� 266 Multiple lytic lesions diffusely distributed in the iliac bones and in the proximal femora of an 11-year-old female with ALL���������������������������������������� 266 (a) Anteroposterior view of the right hip of a child with ALL demonstrates diffuse osteoporosis, a lucent metaphyseal band in the proximal femur and periosteal reaction along the femoral neck and the ipsilateral iliac bone. (b) Leukemic lines can be seen in the metaphyses of the distal femur and of the proximal tibia in a 4-year-old female with ALL, as well as diffuse osteoporosis ����������������������������������������������������������������� 267 Anteroposterior view (left) and lateral view (right) of the right ankle of a child with a triplane fracture. The first image shows a vertical fracture affecting the lateral portion of the distal epiphysis of the tibia and lateral physeal widening, which could be interpreted as a Salter-Harris fracture type III. Nonetheless, there is also a bone fragment involving the posterior and lateral portions of the distal metaphysis, better seen in the lateral view, which demonstrates a coronal fracture of the metaphysis. Complex fractures like this one usually require CT for proper evaluation������������������������������������������������������������������������������������������������� 270 Lateral view of the left ankle demonstrating a type II fracture of the distal tibia with anterior displacement of the epiphysis and of the metaphyseal fragment. Marked osteoporosis is also present ����������������������������� 270

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Fig. 10.3 Radiographs of the left elbow of a child with supracondylar fracture of the humerus. Although the fracture line is quite subtle in the anteroposterior view, additional markers seen on the lateral view include displacement of the anterior and posterior fat planes and absent intersection between the anterior humeral line and the central portion of the distal epiphysis����������������������������������������������������������������������������������������� 271 Fig. 10.4 Reformatted CT images of the left distal humerus of a 9-year-old child in the coronal (a) and sagittal (b) planes show a healed transphyseal fracture (type IV) of the lateral condyle. There is a transphyseal bone bridge between the humeral metaphysis and the anteromedial portion of the capitulum, more evident in (b)������������������������������� 271 Fig. 10.5 (a) Sagittal fat sat T2-WI of the ankles (right ankle – upper row; left ankle – lower row) demonstrate widening and increased signal intensity of the left tibial physis, as well as ipsilateral metaphyseal edema. This acute, non-displaced Salter-Harris type I fracture would be difficult to detect with other imaging methods. Similar findings are present in the right distal femur of a 12-year-old child in (b) (coronal fat sat PD-WI [left] and sagittal T1-WI [right]), but bone marrow edema is less prominent, and physeal widening is more evident as this is a subacute lesion��������������������������������������������������������������������������������������������� 273 Fig. 10.6 T1-WI (left) and fat sat T2-WI (right) of the left knee show subtle lateral displacement of the proximal epiphysis of the fibula, more evident in the coronal images (Salter-Harris lesion type I), with bone marrow edema centered at the physis. There is also extensive edema in the adjacent muscles and a subperiosteal hematoma along the proximal metadiaphysis of the fibula��������������������������������������������������������������������������������� 275 Fig. 10.7 (a) Radiographs of the left elbow demonstrate a fracture line involving the lateral condyle of the humerus, extending from the lateral cortex of the metaphysis to the physis medial to the ossification center of the capitulum. Nonetheless, radiographs do not allow proper assessment of the extension of the fracture into the non-ossified portion of the epiphysis. Coronal T1-WI (b) is also limited to demonstrate the real extent of the fracture, which is clearly shown on fat sat PD-WI (c) (Salter-Harris fracture type IV). Joint effusion and marked edema of the periarticular soft tissues are also present������������������������������������������������������� 276 Fig. 10.8 US of a very young child with right-sided avulsion fracture of the non-ossified medial epicondyle of the humerus. The upper image shows caudal displacement of the avulsed epicondyle, with hypoechogenic fluid interposed between the fragment and the host cartilage (compare with the normal appearance of the left medial epicondyle). In addition to the above described avulsion fracture, the lower image also discloses a subtle zigzag hypoechogenic fracture line coursing through the cartilaginous fragment ����������������������������������������������������� 278 Fig. 10.9 Schematic representation of the Salter-Harris classification of physeal fractures. The physis is represented as a thick line and the fractures as thin lines. While types I and II are physeal and physeal and/or metaphyseal, respectively, types III and IV are associated with epiphyseal involvement and extend to the joint surface. Type V fracture is a compressive physeal lesion, resulting from the action of axial forces ���������� 279 Fig. 10.10 Sagittal T1-WI (left) and fat sat T2-WI (right) of the right ankle. There is widening of the physis of the distal fibula, more evident on T1-WI, with increased signal intensity of the physis itself and of the adjacent bone marrow on fat sat T2-WI (Salter-Harris fracture type I) ��������������������������� 280

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Fig. 10.11 Lateral (upper image) and oblique (lower image) views of the wrist disclosing a physeal and/or metaphyseal fracture of the distal radius, with dorsal angulation and displacement of the epiphysis and of the metaphyseal fragment (Salter-Harris fracture type II)��������������������������������������� 280 Fig. 10.12 Type III fracture of the base of the proximal phalanx of the thumb in a 14-year-old male. Radiograph (a), coronal T1-WI (b, upper row), and sagittal fat sat PD-WI (b, lower row) show a mildly displaced physeal and/or epiphyseal fracture leading to discontinuity of the joint surface. A small metacarpophalangeal effusion is also present��������������������������������������� 281 Fig. 10.13 Coronal T1-WI (left) and fat sat PD-WI (right) of the left ankle of a 12-year-old female demonstrate periphyseal bone marrow edema in the distal tibia and fibula, with a vertical fracture line extending to the joint surface in the medial portion of the tibial epiphysis, also surrounded by marrow edema. These findings correspond to a Salter-Harris fracture type III in the tibia and a non-­displaced type I lesion in the fibula��������������������� 282 Fig. 10.14 Evolution of a surgically treated type II fracture of the distal femur. Formation of bone callus and progressive consolidation of the fracture are evident in serial radiographs, as well as gradual onset of osteoporosis��������������������������������������������������������������������������������������������������������� 283 Fig. 10.15 Radiographs (a), sagittal reformatted CT images (b), and volumerendered reconstructions (c) of an adolescent with sequelae of a surgically corrected elbow fracture. There is irregularity of the joint surfaces, with premature osteoarthritis and flexion deformity��������������������������� 283 Fig. 10.16 Radiographs (a) and reformatted CT images (b) of the right knee of a 10-year-old boy with a remote transphyseal fracture of the distal femur who developed a centrally located transphyseal bone bridge affecting the medial condyle and abnormal widening of the medial physis. (c), radiograph of the wrist and of the forearm of a skeletally immature patient (left image) demonstrates bowing and deformity of the distal radius and ulna, with orthopedic plate and screws in the latter; there is a peripheral transphyseal bone bridge in the distal radius (to which growth recovery lines converge), as well as incongruity of the radiocarpal joint. On the right, radiograph of a young adult with sequelae from an old healed fracture of the distal forearm reveals radial shortening (growth arrest related to physeal injury) and premature osteoarthritis of the wrist, as well as deformity of the distal ulna ��������������������� 285 Fig. 10.17 Old gunshot lesion in the head of the fourth metacarpal bone associated with physeal injury. There is deformity of the metacarpal head and premature physeal closure leading to bone shortening��������������������������������������� 286 Fig. 10.18 Radiographs of the right wrist and distal forearm of a child with old healed fractures of the ipsilateral radius and ulna. There is discrepancy in the length of the forearm bones due to early closure of the ulnar physis and, as a consequence, ulnar shortening. Secondary deformity of the distal radius is also present����������������������������������������������������������������������� 287 Fig. 10.19 Sagittal reformatted CT images (left) and volume-rendered reconstructions (right) of the forearm of a child demonstrating a greenstick fracture of the distal third of the ulna, with discontinuity of the volar cortex and bending of the opposite side of the bone. A complete diaphyseal fracture of the distal radius can be seen in the last image������������������������������������������������������������������������������������������������������������������� 287 Fig. 10.20 Radiographs of the proximal third of the left forearm of a 13-year-old male reveal an incomplete fracture in the posterior cortex of the radius associated with moderate periosteal reaction, without involvement of

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the opposite side, as well as mild volar bowing of this bone. Greenstick fracture ��������������������������������������������������������������������������������������������������������������� 288 Fig. 10.21 Radiographs of the right forearm of the same child, taken some months apart. The first radiograph (left) reveals plastic deformation of the radial mid-diaphysis as well as a subtle incomplete fracture of the lateral cortex of the ulnar mid-diaphysis (more evident in the magnified image) associated with solid periosteal reaction. The follow-up radiograph discloses refracture of the ulna in the same level of the previously described lesion; the fracture is complete in the second radiograph, with exuberant bone callus and extensive periosteal reaction. The plastic deformation of the radius remains unchanged������������������ 288 Fig. 10.22 Radiographs of the distal forearm of a young child demonstrates focal bulging in the anterolateral cortex of the distal diaphysis of the radius, typical of a buckle fracture��������������������������������������������������������������������������������� 289 Fig. 10.23 Radiographs of the forearm displaying plastic deformation of the proximal third of the radius, with diaphyseal bowing and absence of cortical discontinuity������������������������������������������������������������������������������������������� 290 Fig. 10.24 Anteroposterior (left) and lateral (right) views of the right distal forearm of a child display complete fractures of the distal diaphyses of the radius and of the ulna, with dorsal displacement and angulation of the fragments, leading to the classic “bayonet” deformity. The lateral view is more adequate in estimating the real extent of displacement����������������� 291 Fig. 10.25 Sagittal T2-WI (left) and fat sat PD-WI (right) of the left knee of a 13-year-old child at the level of the lateral femoral condyle. There is stripping of the articular cartilage, with fluid in the interface with the subchondral bone, not associated with fractures or detachment of cartilaginous fragments. Extensive bone marrow edema and a large joint effusion are also seen��������������������������������������������������������������������������������� 292 Fig. 10.26 Sagittal T1-WI (left) and fat sat PD-WI (right) of the right knee of a 17-year-old male with recent trauma evidence detachment of a large cartilaginous fragment from the anterior portion of the medial femoral condyle, with exposure of the subchondral bone and extensive bone marrow edema. The displaced cartilaginous fragment is found posterior to the affected condyle and presents signal intensity similar to that of the normal articular cartilage in all sequences��������������������������������������������������� 293 Fig. 10.27 (a) Radiograph of a newborn demonstrates complete fracture of the middle third of the right clavicle, with displacement, angulation, and rotation of the medial portion of this bone (birth trauma). (b) Radiograph of an 11-year-old child discloses a greenstick fracture of the clavicle, with incomplete cortical disruption in the upper (convex) surface and bending of the concave side������������������������������������������������������������� 294 Fig. 10.28 MR-arthrography of the left shoulder of a 16-year-old handball player performed after an episode of anterior glenohumeral dislocation. Transverse (a) and coronal (b) fat sat T1-WI demonstrate classic signs of anterior instability, with posterolateral cortical depression of the humeral head (Hill-Sachs lesion) and extensive rupture of the anterior and/or anterosuperior labrum, as well as avulsion of the adjacent periosteum����������������� 295 Fig. 10.29 (a) A supracondylar fracture of the humerus is clearly seen in the anteroposterior view, with posterior displacement of the distal humerus in the lateral view. (b) Radiographs of the left elbow of a 3-year-old boy disclose a completely displaced supracondylar fracture with no cortical contact between the fragments��������������������������������������������������������������� 296

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Fig. 10.30 Transverse T2-WI (upper left image) and coronal T1-WI (upper right image), T2-WI (lower left image), and STIR image (lower right image) of the right elbow of a child with a type IV fracture of the lateral condyle of the distal humerus. The fracture line, which is nondisplaced and surrounded by bone marrow edema, begins in the lateral cortex of the distal humerus and follows an inferior course, crossing the physis and the non-ossified epiphyseal cartilage ����������������������������������������� 297 Fig. 10.31 Oblique and lateral radiographs of the left elbow of an adolescent (left and central images) reveal joint dislocation and avulsion of the ossification center of the medial epicondyle, which overlaps the lateral condyle in the first image and the coronoid process in the second one. The right image is an anteroposterior view obtained after reduction that demonstrates the ossification center in its usual position, with obvious physeal widening and subtle bone fragmentation����������������������������������������������� 297 Fig. 10.32 Anteroposterior and lateral radiographs of a child with fracturedislocation of the right elbow and avulsion of the medial epicondyle. The bone fragment overlies the olecranon fossa in the anteroposterior view, while the lateral view confirms its intra-articular location ����������������������� 298 Fig. 10.33 MRI of the right elbow of a child with avulsion of the medial epicondyle (coronal and transverse fat sat T2-WI [upper row] and T1-WI [lower row]). The avulsed ossification center, which presents medial displacement and anterior rotation, is attached to the medial collateral ligament, with edematous changes of the adjacent bone marrow and soft tissues��������������������������������������������������������������������������������������� 298 Fig. 10.34 Radiographs of the left elbow and proximal forearm of a patient with Monteggia fracture performed before (left) and after (right) surgical correction. It is important to emphasize that the radiograph at left was taken several years after the traumatic event: only the ulnar fracture was diagnosed in the emergency unit then and the radial dislocation went unnoticed. There is dislocation of the radial head in the first image, as well as pressure erosion in the anterior cortex of the adjacent humerus, with restoration of its normal relationship with the capitulum in the second image. The fracture of the ulnar diaphysis is partially seen in the first image����������������������������������������������������������������������������������������� 299 Fig. 10.35 Salter-Harris type I fractures. In the first two images, coronal T1-WI and gradient-echo image of the wrist of a 13-year-old patient reveal metaphyseal bone marrow edema of the radius and of the ulna, as well as increased signal intensity in the corresponding physes in the second image. Post-gadolinium fat sat T1-WI in the coronal (third image) and sagittal (fourth image) planes disclose enhancement of the physes and of the edematous bone marrow and soft tissues. Physeal widening is more evident in the dorsal portion of the ulna ��������������������������������������������������� 300 Fig. 10.36 Transverse (a) and coronal (b) CT images of the right wrist of a 13-year-old male demonstrate a complete fracture of the scaphoid, with subtle proximal migration of the distal fragment, which is partially interposed between the proximal portion of the scaphoid and the lunate bone, more evident in the coronal plane������������������������������������������������������������� 300 Fig. 10.37 Anteroposterior view of the right hip of a child with a trochanteric fracture of the femur. Pediatric fractures of the proximal femur are rare and usually evident on radiographs��������������������������������������������������������������������� 301 Fig. 10.38 MRI of the left knee of a 14-year-old patient with a Salter-­Harris type II fracture of the distal femur. Coronal T1-WI (left) and fat sat T2-WI (right) disclose an oblique fracture line across the femoral metaphysis,

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extending from the lateral cortex to the physis. There is obvious physeal widening, medial to the metaphyseal fracture line, representing the horizontal component of the lesion. A subchondral bone bruise is seen on the lateral femoral condyle ������������������������������������������������������������������� 301 Fig. 10.39 Salter-Harris fracture type III of the proximal tibia. Sagittal T1-WI (a) and fat sat T2-WI in the sagittal (b), transverse (c), and coronal (d) planes demonstrate physeal widening associated with a vertical fracture of the lateral portion of the tibial epiphysis. There is extensive bone marrow edema in the tibial epiphysis and metaphysis��������������������������������������� 302 Fig. 10.40 Coronal fat sat T2-WI of the left knee disclose a Salter-Harris fracture type IV of the proximal tibia extending from the proximal metadiaphysis to the articular surface of the lateral plateau. The fracture line is hyperintense, surrounded by bone marrow edema��������������������� 303 Fig. 10.41 Salter-Harris fracture type I of the distal fibula. Sagittal T1-WI (left) and fat sat PD-WI (right) of a 14-year-old patient reveal physeal widening (more evident on T1-WI) and edematous changes of the physis and of the adjacent bone marrow (more evident on fat sat PD-WI)��������������������������������������������������������������������������������������������������������������� 304 Fig. 10.42 Salter-Harris fracture type II of the distal fibula in an 11-year-old child. Even though a physeal and/or metaphyseal fracture line is quite evident on oblique views of the ankle (a), sagittal T1-WI (b, left) and fat sat PD-WI (b, right) demonstrate additional findings, such as marked bone marrow and soft-tissue edema����������������������������������������������������������������������������� 305 Fig. 10.43 CT scout view (upper left image), reformatted images in the coronal (upper right image) and sagittal (lower left image) planes, and transverse image (lower right image) of the right ankle of a child who sustained a recent traumatic injury. There is a complex Salter-­Harris fracture type IV involving the metaphysis, the physis, and the epiphysis of the tibia, in addition to a fracture of the medial malleolus. CT images are more accurate to demonstrate the real extent of complex fractures like this one ����������������������������������������������������������������������������������������� 306 Fig. 10.44 (a) Axial (left) and volume-rendered (right) CT images of the right ankle of a 13-year-old female (same patient as in Fig. 2.18) reveal a fracture involving the distal tibial epiphysis and the anterolateral portion of the adjacent physis (Tillaux fracture), with displacement of the resulting bone fragment; the remainder of the physis is already closed in this Salter-Harris type III fracture. (b) Coronal and sagittal reformatted CT images of the right ankle of a 13-year-old boy disclose a tibial fracture with three components (triplane fracture), one of them crossing the epiphysis vertically, other coursing horizontally through the physis, and a third one in the coronal plane involving the metaphysis, findings that are elegantly displayed in volume-rendered reconstructions in (c)����������������������������� 307 Fig. 10.45 MRI of the right knee of a 16-year-old patient with acute infrapatellar pain during a soccer match. Sagittal T1-WI (left) and fat sat PD-WI (right) reveal a partial tear of the proximal patellar tendon – which is thickened and heterogeneous – adjacent to its origin, with edema of the Hoffa’s fat pad and of the bone marrow of the inferior pole of the patella����������������������������������������������������������������������������������������������������������������� 308 Fig. 10.46 Fat sat PD-WI in the transverse (a), sagittal (b, left), and coronal (b, right) planes demonstrate edema of the muscle fibers in the distal myotendinous junction of the brachial biceps of a 17-year-old patient, without muscle tear or intramuscular collections, representing a muscle sprain. Axial (c) and coronal (d) fat sat T2-WI of the thighs of a

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15-year-old male disclosing feather-like edema surrounding the musculotendinous junction of the rectus femoris bilaterally, notably in the left thigh, where a small amount of fluid can be seen along the affected tendon, without frank tear. Bone marrow edema is incidentally seen on the left side of the pubic symphysis������������������������������������������������������� 309 Fig. 10.47 Adolescent with acute pain in the anterior aspect of the right thigh after trauma during a soccer match. The left image is a longitudinal US scan with extended field-of-view that demonstrates a complete tear of the rectus femoris, with superior retraction (arrows). In the right image, the inferior portion of the retracted muscle belly is shown in higher detail, with fluid interposed between it and the vastus intermedius ����������������������������� 310 Fig. 10.48 (a) Transverse T2-WI (left) and fat sat PD-WI (right) of a 15-year-­old patient with an acute sprain of the right ankle display thickening and heterogeneous signal intensity of the anterior talofibular ligament, without discontinuity of its fibers; marked edema of the periarticular soft tissues is also seen, as well as joint effusion. (b) Axial T1-WI (left) and fat sat T2-WI (right) of the left ankle of an 8-year-old boy disclose thickening and interstitial hyperintensity in the anterior talofibular ligament on T2-WI, which presents ill-defined contours on T1-WI; edema of the surrounding soft tissues and bone marrow edema of the distal fibula are also evident������������������������������������������������������������������������������� 311 Fig. 10.49 (a) Sagittal fat sat PD-WI of a 16-year-old male seen after knee trauma during a basketball match reveal a complete tear of the anterior cruciate ligament, with moderate joint effusion, absent visualization of the ligament fibers, typical bone bruises in the lateral femoral condyle and in the lateral tibial plateau, and anterior translation of the tibia. (b) Sagittal fat sat PD-WI and coronal oblique T2-WI of another patient disclose a complete tear of the distal portion of the anterior cruciate ligament, along with joint effusion and edema of the posterior soft tissues������������������������������������� 312 Fig. 10.50 Young child with left knee trauma and clinical evidence of joint instability. Sagittal T2-WI (upper row, left) and coronal fat sat PD-WI (lower row, left) reveal an intact anterior cruciate ligament. Nonetheless, its tibial insertion is ill-defined, with adjacent bone marrow edema indicating bone avulsion; subchondral bone marrow edema is also present in the lateral femoral condyle. A lateral radiograph (right) clearly demonstrates the suspected bone avulsion at the tibial insertion of the anterior cruciate ligament������������������������������������������� 313 Fig. 10.51 A 6-year-old male with chronic pain in the right knee. Coronal fat sat PD-WI (a) and sagittal T1-WI and T2-WI (b) disclose a transverse tear across the whole extension of the medial meniscus, with a loculated parameniscal cyst protruding anteriorly and medially. Despite the young age of the child, imaging findings are identical to those of similar lesions seen in adults������������������������������������������������������������������������������� 313 Fig. 10.52 Sagittal T1-WI (left) and fat sat PD-WI (right) of the right knee of a 16-year-old male. There is a vertical full-thickness tear at the periphery of the posterior horn of the medial meniscus. The criteria used to diagnose meniscal lesions in children and adults are essentially the same ������������������������������������������������������������������������������������������������������������������� 314 Fig. 10.53 Radiographic findings in two children who suffered physical abuse. Radiographs of the forearms and of the legs (left) display focal areas of periosteal reaction in the mid-diaphyses of the right ulna and of the left radius, with symmetric and bilateral fractures of the distal diaphyses of the tibiae and fibulae. A lateral radiograph of the sternum of the second

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patient (right) discloses a destructive lesion of the sternal body, with ill-defined borders, bone fragmentation, and anterior displacement of its lower portion, related to osteomyelitis (the child was subjected to recurrent burns on the anterior portion of the chest, intentionally caused by lit cigarettes)��������������������������������������������������������������������������������������� 315 Fig. 10.54 A 2-month-old child victim of physical abuse admitted to the intensive care unit. (a) Volume-rendered CT reconstructions demonstrate a complex, multi-fragmented skull fracture that was associated with bilateral subdural collections and brain contusions (not shown). (b) Radiographs of the upper limbs of the same child disclose multiple fractures in different stages of healing: spiral diaphyseal fractures of the bones of the left forearm and a transverse fracture of diaphysis of the ipsilateral humerus (which presents diastasis, angulation, and fragmentation) can be seen, as well as an ipsilateral supracondylar fracture. There is a complete fracture with gross displacement of the distal portion of the right humerus, as well as thick periosteal reaction along the diaphysis. The distal portion of the right forearm is seen in further detail in (c): this image reveals subtle corner fractures in the radius and in the ulna, more evident in the former, in which there is also an incomplete metaphyseal fracture associated with mild bowing. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)����������� 315 Fig. 11.1 In (a), radiographs of the right hip of an adolescent with acute avulsion of the anterior inferior iliac spine show a partially corticated bone fragment in the soft tissues adjacent to the apophyseal site, without evidence of chronic apophysitis. In (b), MRI of another patient demonstrates similar findings, with acute avulsion and mild displacement of the anterior inferior iliac spine, without signs of chronic inflammation. Transverse T1-WI (upper row, left) and T2-WI (upper row, right) disclose increased signal intensity of the periapophyseal soft tissues, related to post-traumatic hemorrhage, while sagittal fat sat T2-WI (lower row) reveal extensive soft-tissue edema and allow accurate assessment of the extent of the avulsion. Additional transverse T1-WI (c) and fat sat T2-WI (d) of the pelvis of the same patient disclose a large hematoma deeply situated relative to the right iliac muscle containing a fluid-fluid level. (a, courtesy of Dr. Marcelo Coelho Avelino, MD, Medimagem, Teresina, Brazil) ������������������������� 320 Fig. 11.2 Radiographs of three distinct patients with chronic right-­sided apophysitis of the anterior inferior iliac spine displaying different appearances of this condition on imaging. Increased size and abnormal shape of this apophysis are present in all patients. In (a), periosteal reaction and bone neoformation are evident, which are notably absent in the acute lesion of Fig. 11.1a. In (b), the apophysis has a pseudotumoral appearance, with bone deformity, metaphyseal remodeling, and physeal widening. In (c), despite the obvious increase of the apophyseal size, bone neoformation and/or remodeling is absent����������� 322 Fig. 11.3 CT of the pelvis of a 14-year-old soccer player. Transverse images (a), sagittal reformatted images (b) and volume-rendered reconstruction (c) display increased size of the apophysis of the right anterior inferior iliac spine, as well as physeal widening and bone neoformation. Apophysitis is more evident when the affected apophysis is compared to the contralateral one��������������������������������������������������������������������������������������� 322

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Fig. 11.4 In (a), transverse T1-WI (upper left image), T2-WI (upper right image) and STIR image (lower left image) reveal findings similar to those of the patient of Fig. 11.3; MRI, however, is able to detect edematous changes of the bone marrow and of the soft tissues, which are related to chronic inflammation and not evident on CT. Sagittal gradient-echo image (lower right image) is useful to demonstrate increased size and irregular contours of the affected apophysis, as well as physeal widening. In (b), post-gadolinium fat sat T1-WI of the same patient (upper row) display enhancement of the abovementioned edematous areas, while CT images (lower row) reveal solid and thick periosteal neoformation, which is difficult to demonstrate on MRI����������������������������������� 323 Fig. 11.5 Sagittal T1-WI (a), fat sat PD-WI (b) and post-gadolinium fat sat T1-WI (c) of a patient with apophysitis of the tibial tubercle show bone fragmentation in addition to thickening and heterogeneity of the distal portion of the patellar tendon. Furthermore, there is fluid distension of the deep infrapatellar bursa and edematous changes of the bone marrow and of the adjacent soft tissues, which show enhancement on post-contrast images������������������������������������������������������������������������������������������� 324 Fig. 11.6 MRI of the hips of a 14-year-old adolescent with chronic apophysitis of the right anterior inferior iliac spine. Transverse T1-WI (a), T2-WI (b) and fat sat T2-WI (c) reveal subtle increase of the size of the affected apophysis and adjacent bone marrow edema, which are absent in the opposite side. In (d), sagittal fat sat T2-WI of the right hip demonstrate, in addition to the abovementioned findings, widening and increased signal intensity of the affected physis������������������������������������������������� 324 Fig. 11.7 A 15-year-old patient with long-standing right-sided inguinal pain related to chronic apophysitis of the anterior inferior iliac spine. Transverse T1-WI (a), T2-WI (b) and STIR images (c) and sagittal T2-WI and fat sat T2-WI (d) display findings that are very similar to those of the patient of Fig. 11.6, except for absence of significant physeal widening ����������������������������������������������������������������������������������������������� 325 Fig. 11.8 Axial CT images of the pelvis of two distinct male soccer players with chronic traction apophysitis of the right anterior superior iliac spine (13-year-old [upper row] and 16-year-old [lower row]). Both patients present increased size of the affected apophyses when compared to the contralateral side (more evident in the older individual), physeal widening, and periosteal reaction (more extensive in the younger patient) ��������������������������������������������������������������������������������������������������������������� 325 Fig. 11.9 In (a), axial T1-WI and fat sat T2-WI (left) and coronal fat sat T2-WI (right) of the ischia of a 12-year-old female high-performance gymnast disclose extensive bone marrow edema affecting the entire left ischial tuberosity, without soft-tissue involvement, findings compatible with incipient apophysitis. In (b), similar findings are seen in a 14-year-old male soccer player (coronal and axial fat sat T2-WI), in addition to periosteal reaction and edema of the adjacent soft tissues, which are indicative of a more chronic process������������������������������������������������������������������� 326 Fig. 11.10 Bone deformity related to an old healed lesion of the left anterior superior iliac spine incidentally found during an abdominal CT scan in a 36-year-old male (former soccer player during the adolescence). On transverse images (upper row), there is prominence of the apophysis, with a bony protuberance that is also evident on a sagittal reformatted image (lower right image - compare with the normal apophysis in the lower left image)������������������������������������������������������������������������������������������������� 327

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Fig. 11.11 Lateral view of the left knee of a child with OSD showing fragmentation and sclerosis of the tibial tubercle����������������������������������������������� 327 Fig. 11.12 MRI of the right knee of a 13-year-old child with OSD. Sagittal T1-WI (a) and fat sat T2-WI (b) and coronal fat sat T2-WI (c) display fragmentation of the apophysis of the tibial tubercle and extensive bone marrow edema, as well as edema of the infrapatellar fat pad and thickening of the distal portion of the patellar tendon ��������������������������������������� 328 Fig. 11.13 A 13-year-old-patient with OSD. In addition to the findings above described for the patient of Fig. 11.12, sagittal PD-WI (a) and STIR image (b) and transverse STIR image (c) disclose a sclerotic bone fragment with low signal intensity in both sequences and fluid in the deep infrapatellar bursa��������������������������������������������������������������������������������������� 328 Fig. 11.14 Lateral radiograph (a) and sagittal T1-WI (b) and fat sat PD-WI (c) of an adult with late-stage sequelae of OSD complaining of anterior knee pain. The radiograph shows an ossicle projected over the distal portion of the patellar tendon, with irregularity of the tibial tubercle. MRI corroborates the radiographic findings, demonstrating cystic and/or edematous changes of the bone marrow of the tibial tubercle and of the ossicle, as well as thickening of the distal patellar tendon and edema of the adjacent soft tissues��������������������������������������������������������������������������������������� 329 Fig. 11.15 In (a), sagittal T1-WI (upper left image), T2-WI (upper right image), and STIR image (lower left image) and coronal fat sat PD-WI (lower right image) of an 11-year-old soccer player with SLJD display bone marrow edema and fragmentation of the inferior pole of the patella; edematous changes are also seen in the infrapatellar fat pad. In (b), sagittal fat sat T2-WI (left) and T1-WI (right) of a 12-year-old male with SLJD disclose overall similar findings, with thickening and increased signal intensity of the proximal portion of the patellar tendon and edema of the bone marrow and of the adjacent soft tissues, without discernible bone fragmentation, though������������������������������������������������������������� 330 Fig. 11.16 Sagittal T1-WI (a) and T2-WI (b) and transverse STIR image (c) of a 14-year-old patient with SLJD display bone fragmentation, more evident than that observed in the patient of Fig. 11.15. Nonetheless, the edematous changes are less prominent and almost exclusively confined to the avulsed bone fragment. Subtle thickening of the proximal patellar tendon is also present����������������������������������������������������������������������������� 331 Fig. 11.17 A 27-year-old patient with symptomatic sequelae of SLJD. MRI discloses chronic avulsion of a large bone fragment with corticated borders adjacent to the inferior patellar pole, as well as thickening of the proximal patellar tendon and edema of the adjacent soft tissues����������������� 332 Fig. 11.18 Transverse CT image (a) and sagittal reformatted image (b) of a 13-year-old runner with left infrapatellar pain disclose thickening and focal hypodensity of the proximal patellar tendon due to tendinopathy, without abnormalities of the adjacent bone or of the soft tissues����������������������� 332 Fig. 11.19 Sagittal T1-WI (left) and fat sat PD-WI (right) of the right ankle of an 8-year-old girl with Sever disease disclosing fragmentation and bone marrow edema in the calcaneal apophysis, which is markedly hypointense on T1-WI. A small amount of fluid is present adjacent to the site of insertion of the Achilles tendon��������������������������������������������������������� 333 Fig. 11.20 Radiographs (a) of a 6-year-old male with left-sided Kohler disease disclose a sclerotic tarsal navicular bone, which is reduced in size and presents slightly irregular contours. In (b), axial T1-WI (left), fat sat T2-WI (center) and post-gadolinium fat sat T1-WI (right) of the left

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ankle of the same patient display heterogeneous signal intensity of the ossified portion of the tarsal navicular, with predominantly edematous changes in the medial portion and hypointense sclerosis in the central and lateral portions; markedly decreased post-contrast enhancement can be seen in the sclerotic bone, with higher than normal enhancement in the medial portion������������������������������������������������������������������������������������������� 334 Fig. 11.21 Radiographs (a) and reformatted CT images (b) of the right shoulder of a 14-year-old male with acromial apophysitis. There is sclerosis, diminished size and fragmentation of the ossification center of the acromial apophysis, as well as subtle physeal widening ����������������������������������� 334 Fig. 11.22 Symptomatic tripartite patella in a 17-year-old athlete. Radiographs of the left knee (a) demonstrate two superolateral ossification centers not incorporated to the body of the patella. Coronal (b) and transverse (c) fat sat PD-WI display bone marrow edema adjacent to the synchondrosis, which presents increased signal intensity ��������������������������������� 335 Fig. 11.23 OD of the medial femoral condyle of the left knee. Radiographs demonstrate a subchondral lucency in the mesial portion of the affected condyle containing small bone fragments, more evident in the anteroposterior view������������������������������������������������������������������������������������������� 336 Fig. 11.24 Anteroposterior (a) and lateral (b) views of the left knee demonstrating OD of the medial femoral condyle. The lesion and the in situ bone fragments are much larger than those seen in the patient of Fig. 11.23������������� 336 Fig. 11.25 Anteroposterior (a) and lateral (b) views disclose bone fragments adjacent to the articular surface of the patella, related to OD (see Fig. 11.30). However, radiographs are not suitable to assess the stability of the lesion. In another patient, axial view of the patella (c) demonstrates more properly the osteochondral bed and the in situ bone fragments but, once again, it is not possible to evaluate their stability��������������� 337 Fig. 11.26 Coronal fat sat PD-WI (a) and sagittal T2-WI (b) of the left knee of an adolescent with OD of the medial femoral condyle. There is an in situ bone fragment displaying heterogeneously high signal intensity in (a) and low signal intensity in (b). Adjacent bone marrow edema is also present, as well as a subtle hyperintense halo surrounding the fragment in (a). The overlying cartilage is irregular, with heterogeneous signal intensity��������������������������������������������������������������������������������������������������������������� 337 Fig. 11.27 Multifocal OD of the right knee affecting the medial femoral condyle and the lateral tibial plateau. Anteroposterior view (left) demonstrates typical subchondral lucencies, with in situ bone fragments. Sagittal T2-WI (upper row, right) and coronal fat sat PD-WI (lower row, right) reveal that the bone fragments have heterogeneous signal intensity, with preservation of the overlying cartilages. Cyst-like lesions are seen along the interfaces between the fragments and the host bones. The interfaces are hyperintense on both sequences��������������������������������������������������� 338 Fig. 11.28 Sagittal T1-WI (a) and T2-WI (b) and coronal fat sat PD-WI (c) and gradient-echo image (d) of the knee of an adolescent with OD of the medial femoral condyle. The fragment presents variable signal intensity in the different sequences, with adjacent bone marrow edema and multiple small cysts along the interface fragment and/or host bone. The overlying cartilage is preserved������������������������������������������������������������������� 338 Fig. 11.29 Coronal fat sat PD-WI of the left knee acquired in intervals of 1 year, from age 7 to age 9. The first image (a) evidences OD of the medial femoral condyle with an in situ bone fragment of high signal intensity, surrounded by bone marrow edema, as well as hyperintensity in the interface fragment

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and/or host bone and heterogeneous signal intensity of the overlying cartilage. The second image (b) reveals involution of the bone marrow edema and heterogeneous signal intensity of the fragment and of the cartilage, while the third one (c) demonstrates virtually complete incorporation of the bone fragment 2 years later, emphasizing the relative importance of the classic signs of instability in the juvenile form of OD������������������339 Fig. 11.30 Sagittal T1-WI (upper left image) and T2-WI (upper right image) and fat sat PD-WI in the transverse (lower right image) and coronal (lower left image) planes of the right knee of the same patient of Fig. 11.25. There is OD of the patella with in situ bone fragments that display low to intermediate signal intensity in all sequences, surrounded by a hyperintense halo on fat sat PD-WI. The overlying cartilage is irregular and heterogeneous. A cartilaginous loose body undetectable on radiographs can be seen posterolateral to the anterior cruciate ligament, with intermediate signal intensity on T1-WI and intermediate to low signal intensity in the other sequences��������������������������������������������������������������� 339 Fig. 11.31 Chronic OD in a 21-year-old patient. Coronal fat sat PD-WI reveals an “empty” osteochondral bed in the medial femoral condyle, filled with synovial fluid, as well as a large osteochondral loose body adjacent to the intercondylar notch. The complete lack of bone marrow edema is indicative of chronic evolution��������������������������������������������������������������������������� 340 Fig. 11.32 Radiographs (a) and CT images (b) of the right ankle of a 16-year-old female with OD of the talus. The radiographs evidence a subchondral lucency in the posteromedial convexity of the talar dome, containing bone fragments, findings clearly demonstrated on CT. Nonetheless, neither of these methods provide accurate information about the overlying cartilage or concerning the stability of the lesion. Sagittal fat sat PD-WI (c) and 3D gradient-echo images (d) reveal adjacent bone marrow edema (more evident in c) and thinning and/or irregularity of the overlying cartilage (more clearly seen in d), without evidence of frank instability��������������������������������������������������������������������������������������������������� 341 Fig. 11.33 MRI of the left ankle of a 15-year-old male soccer player with persistent joint pain 2 months after a traumatic episode. Sagittal T1-WI (upper left image) and fat sat T2-WI (lower left image) and coronal PD-WI (upper right image) and fat sat PD-WI (lower right image). There is an osteochondral lesion in the medial convexity of the talar dome with an in situ fragment, surrounded by bone marrow edema. Bone marrow edema is also seen in the lateral malleolus (countrecoup lesion), with swelling of the periarticular soft tissues����������������������������������������� 341 Fig. 11.34 Evolution of juvenile OD of the talus. Sagittal T1-WI (left images) and fat sat PD-WI (right images) acquired at age 15 (a) and age 22 (b) reveal an in situ bone fragment in both studies. Despite the edematous changes of the bone fragment and the irregularity of the articular cartilage in (b), the stability of the lesion after 7 years of conservative treatment emphasizes the more benign nature of juvenile OD if compared to the adult form��������������������������������������������������������������������������������� 342 Fig. 11.35 A 14-year-old elite-level female gymnast. Sagittal fat sat T2-WI (a) and post-contrast fat sat T1-WI (b) demonstrate OD of the medial convexity of the talus. There is continuity between the bone fragment (which presents post-gadolinium enhancement) and the host bone. Enhancement is also present in the interface between the fragment and the host bone, which appears hyperintense on fat sat T2-WI. Perilesional bone marrow edema is present as well������������������������������� 343

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Fig. 11.36 A 16-year-old patient with OD of the capitulum. Anteroposterior view (upper left image) discloses a subchondral lucency in the capitulum containing bone fragments. Coronal gradient-­echo image (upper right image) and transverse T1-WI (lower left image) and fat sat PD-WI (lower right image) demonstrate that the bone fragment is predominantly hypointense on T1-WI and heterogeneous on PD-WI, surrounded by bone marrow edema. The interface with the host bone appears hyperintense on PD-WI, with a small cyst-­like lesion in the adjacent cancellous bone������������������������������������������������������������������������������������� 343 Fig. 11.37 MR-arthrography of the left shoulder of a 14-year-old female complaining of pain and tenderness on the lateral aspect of this joint (“little leaguer’s shoulder”). Coronal fat sat T2-WI (a) and fat sat T1-WI in abduction and external rotation (b) reveal metaphyseal bone marrow edema radiating from the physis, which presents mild lateral widening, more evident in (b). (Courtesy of Dr. Daniel Sá, MD, Image Memorial Diagnósticos da America S.A., Salvador, Brazil) ����������������������������� 344 Fig. 11.38 In (a), radiograph of the left hip (upper left image) demonstrates that an imaginary line drawn along the lateral cortex of the femoral neck does not intersect the femoral epiphysis. Transverse STIR image (upper right image), coronal STIR image (lower left image) and postgadolinium fat sat T1-WI (lower right image) evidence posteroinferior slippage of the epiphysis, with juxtaphyseal bone marrow edema and physeal widening. Post-gadolinium enhancement is evident both in the physis and in the edematous bone marrow. In (b), radiograph of a 12-year-old male taken at admission (left image) discloses bilateral SCFE, more evident in the left hip, with subtle physeal widening and mild epiphyseal slippage in the contralateral joint; follow-up radiograph obtained 3 months later (right image) shows obvious bilateral SCFE and fixation with cannulated screws������������������������������������������� 345 Fig. 11.39 Bilateral SCFE in a 14-year-old patient. Transverse CT image (a) and sagittal reformatted images (b) reveal posteroinferior slippage of the proximal femoral epiphyses, more important in the right hip, where physeal widening is more evident. Thickening of the posterior cortices of the femoral necks is also evident on sagittal images. (c) Reformatted CT images of the left hip of a 9-year-old girl with SCFE disclose obvious physeal widening and irregular physeal contours, as well as epiphyseal slippage��������������������������������������������������������������������������������������������� 346 Fig. 11.40 CT scan of the pelvis of an elderly patient with late-stage sequelae of bilateral SCFE. There is deformity of the proximal femora, with marked retroversion of the femoral heads and secondary osteoarthritis (note the remarkable similarity with Fig. 11.39a)����������������������������������������������� 347 Fig. 11.41 Left-sided SCFE in a 13-year-old adolescent. The upper left image (coronal fat sat PD-WI including both hips) demonstrates bone marrow edema centered about the left physis that is absent in the contralateral hip, associated with joint effusion. Transverse fat sat PD-WI (upper right image) and coronal fat sat PD-WI (lower left image) and T1-WI (lower right image) show posteroinferior slippage of the proximal femoral epiphysis and physeal widening, as well as the above described juxtaphyseal bone marrow edema����������������������������������������������������������������������� 348 Fig. 11.42 Stress fracture of the calcaneus in a skeletally immature patient. There is a band of sclerosis perpendicular to the bone trabeculae, typical of stress fractures in this site����������������������������������������������������������������������������������� 348

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Fig. 11.43 A 11-year-old ballerina complaining of pain in both feet. Transverse fat sat T2-WI of the right foot disclose several areas of bone marrow edema from the first to the third metatarsals, with focal thickening of the medial cortex of the second one, without discernible fracture lines. Multiple foci of bone marrow edema were also present in the left foot (not shown) due to stress reaction related to physical activity��������������������������� 349 Fig. 11.44 A 12-year-old soccer player with pain in the right ankle that increased with physical activity. Sagittal T1-WI (a) and fat sat T2-WI (b) and coronal fat sat T2-WI (c) demonstrate an anterolateral fracture line in the trabecular bone of the distal tibial metaphysis, coursing parallel to the growth plate and reaching the lateral cortex, surrounded by bone marrow edema. These findings are typical for a stress fracture������������������������� 349 Fig. 12.1 Young child with active JIA in the cervical spine. Lateral radiograph discloses irregularity of the facets related to erosive joint disease from C2 to C5, with minimal anterior slippage of C2. There is also atlantoaxial instability, with an increased interval between the anterior arch of C1 and the odontoid peg������������������������������������������������������������������������� 353 Fig. 12.2 MRI of the cervical spine of a 13-year-old female with active JIA. Sagittal fat sat T2-WI (upper left image) and post-­gadolinium fat sat T1-WI in the transverse (upper right image) and coronal (lower row) planes reveal ankylosis of the facet joints in C4–C5. Left-sided erosions and post-contrast enhancement are seen in C2–C3 and C3–C4 and in C5–C6, bilaterally (Courtesy of Dr. Christiane Maria França, MD, Hospital Universitário de Brasília – UnB, Brasília, Brazil)����������������������� 354 Fig. 12.3 Oblique radiograph of the cervical spine of a patient with longstanding JIA reveals extensive ankylosis of the facet joints. The C5–C6 level is spared, with premature and atypical osteoarthritis of the facet joints and irregularity and sclerosis of the endplates at this level related to excessive solicitation of the only cervical segment with preserved mobility. Calcifications of the nucleus pulposus are present in all cervical discs������������������������������������������������������������������������������������������������������� 355 Fig. 12.4 Classic radiographic findings of long-standing spinal JIA can be seen in (a), with vertebral hypoplasia from C3 to C7, squaring of the vertebral bodies and facet joint ankylosis, the latter more evident between C3 and C5. Ankylosis of the median atlantoaxial joint is also present, as well as reduced height of the disc spaces and peripheral disc calcifications from C3–C4 to C5–C6. In (b), reformatted sagittal CT images of the thoracic spine of a 10-year-old female with unremitting systemic JIA and prolonged corticosteroid therapy reveal diffuse osteoporosis, multiple vertebral insufficiency fractures, and anterior vertebral wedging more evident in T5, T6, T7, T12, and L1; there is sclerosis of the bone adjacent to the upper endplates of T5 and T7 and the lower endplate of L1������������������������������������������������������������������������������������� 355 Fig. 12.5 Ankylosis of the facet joints of C2–C3 can be seen in this lateral view of the cervical spine of a child with JIA. Note the normal appearance of the facet joints below this level, with regular and smooth surfaces, in contradistinction to those seen in the child of Fig. 12.1������������������������������������� 356 Fig. 12.6 Lateral view (hyperflexion) of the craniovertebral transition of a patient with JIA demonstrates C1–C2 instability, with anterior translation of the atlas relative to the odontoid������������������������������������������������������������������������� 356 Fig. 12.7 Pyogenic spondylodiscitis of L3–L4 in a young child. Lateral radiograph reveals reduced height of the affected disc space, with loss of definition of the adjacent vertebral endplates (Courtesy of Dr.

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Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)��������������������������������������� 357 Fig. 12.8 Lateral radiographs of the cervical spine of a 13-year-old child with pyogenic spondylodiscitis, taken 20 days apart. The first radiograph (left) shows reduced height of the C4–C5 disc space, with loss of definition of the upper endplate of C5 and swelling of the prevertebral soft tissues. The second radiograph (right) demonstrates rapid evolution of the infectious process, with angular deformity of the spine centered about C4 (related to bone destruction, collapse and anterior wedging of this vertebral body), marked osteoporosis of the vertebral bodies from C3 to C5, and reduced height of the corresponding disc spaces. In addition, there is marked swelling of the prevertebral soft tissues leading to compression of the pharyngeal air column����������������������������� 357 Fig. 12.9 Sagittal T2-WI (first image) and fat sat T1-WI (second image) of an 11-year-old female with pyogenic discitis in L3–L4 reveal reduced height and abnormal signal intensity of the affected disc, with destruction of the adjacent endplates and extension of the infectious process to the contiguous vertebral bodies. There is also extensive bone marrow edema surrounding the areas of bone destruction. A small subligamentous collection can be seen posterior to the upper portion of the vertebral body of L4. Sagittal (third image) and coronal (fourth image) post-gadolinium fat sat T1-WI demonstrate enhancement of the osteodiscal focus of infection, of the subligamentous abscess, of the areas of bone marrow edema, and of the edematous paravertebral soft tissues (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)��������������������������������������������������������������������������������������������������� 358 Fig. 12.10 Pyogenic discitis of L4–L5. Sagittal T1-WI (upper row), T2-WI (central row), and post-contrast T1-WI (lower row) disclose diffuse reduction of the height of the affected disc, which presents abnormal signal intensity in all sequences, with destruction of the adjacent endplates and associated bone marrow edema. Post-­gadolinium images demonstrate diffuse and intense enhancement of the infected disc and of the adjacent bone (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)������������������������������������������������������������������������������������� 359 Fig. 12.11 Transverse post-gadolinium fat sat T1-WI of a 3-year-old child with bacterial spondylodiscitis of L5–S1. There is diffuse enhancement in the affected disc, in the bone marrow of the adjacent vertebrae, in the prevertebral and paravertebral soft tissues, and in the epidural space. Despite the extensive involvement of the epidural space, the absence of fluid collections and the diffuse – instead of circumscribed – appearance of post-contrast enhancement favor phlegmon over abscess in this case����������������������������������������������������������������������������������������������������������� 360 Fig. 12.12 Transverse CT images (left) and post-gadolinium fat sat T1-WI (right) acquired approximately at the same levels in a child with pyogenic spondylodiscitis of the upper lumbar spine. In spite of the excellent anatomic detail of CT for bone structures, allowing accurate assessment of the destruction of the vertebral endplates, the evaluation of soft-tissue abnormalities is poor if compared to that obtained with MRI. In the latter, in addition to bone destruction and post-contrast enhancement of the bone marrow, there is also enhancement of the epidural and paravertebral soft tissues, extending to the foramina,

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surrounding the emerging nerve roots and leading to anterior compression of the thecal sac (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)������������������������������������������������������������������� 360 Fig. 12.13 Contrast-enhanced CT of the neck of the same patient of Fig. 12.8 performed on the same day of the second radiograph. There is obvious destruction of the body of C4 (left images), with bone fragments extending to the spinal canal. A large prevertebral abscess is also seen, displacing the pharyngeal air column (right images). In addition, there is obliteration of the cervical fat planes (with diffuse post-contrast enhancement) and increased density of the epidural space due to post-­contrast enhancement, with mass effect leading to circumferential compression and deformation of the spinal cord ����������������������������������������������� 361 Fig. 12.14 Chest X-ray of a young child (left) disclosing an opacity in the right upper lobe related to pulmonary tuberculosis. The right image is a lateral radiograph of the lumbar spine of the same patient demonstrating collapse of the vertebral body of L2, with angular deformity of the spine and destruction of the inferior endplate of L1. A paravertebral soft-tissue mass with peripheral calcifications is also present. Tuberculous spondylodiscitis ��������������������������������������������������������������� 362 Fig. 12.15 Small child presenting a fistulous orifice in the right groin and caseous discharge. Fistulography with injection of iodinated contrast (left image) discloses opacification of the iliopsoas bursa, which presents irregular contours. The primary site of disease is located in L2–L3, with collapse and anterior wedging of L2 and destruction of the upper endplate of L3 (right image). The disc space is relatively preserved, in spite of the advanced degree of bone destruction. Vertebral tuberculosis and tuberculous iliopsoas bursitis����������������������������������������������������������������������� 362 Fig. 12.16 Tuberculous spondylodiscitis of L1–L2. Radiographs of the upper lumbar spine display reduced height of L1–L2, with destruction of the adjacent endplates and extensive osteolysis of L2, whose vertebral body presents left anterolateral wedging and right tilting ��������������������������������� 363 Fig. 12.17 Spinal tuberculosis affecting the lower thoracic segment. Radiographs demonstrate collapse of T9, with extensive bone destruction and anterior wedging of this vertebral body leading to accentuation of the normal kyphosis. The superior endplate of T10 is eroded and irregular, with reduced height of the corresponding disc space����������������������������������������� 363 Fig. 12.18 In (a), axial CT images of the middle thoracic spine of a 9-year-old girl with spinal tuberculosis disclose marked destruction associated with bone fragmentation of the vertebral bodies and a large prevertebral and paravertebral mass with soft-tissue density; periosteal reaction is present in the adjacent ribs. The figure (b) displays a CT-guided aspiration of a right paravertebral abscess in another patient with tuberculous spondylodiscitis of the thoracic spine: the patient is lying in the prone position, and the tip of the needle is located inside the abscess. There is extensive destruction of the vertebral body and of part of the neural arch. A left-sided paravertebral abscess is also present, adjacent to the descending aorta������������������������������������������������������������������������� 364 Fig. 12.19 Sagittal T1-WI (left images), fat sat T2-WI (center images), and post-gadolinium fat sat T1-WI (right images) of the thoracic spine of a 9-year-old boy with vertebral tuberculosis. There are marked destruction and anterior wedging of the vertebral body of T6, with bone marrow edema and post-gadolinium enhancement of the vertebral

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bodies of T4 through to T7 (extending to the neural arches) and a large prevertebral and/or paravertebral abscess exhibiting peripheral enhancement; this abscess is the cause of non-contiguous involvement of T4. Destruction of the endplates adjacent to T6 and an intraosseous abscess in the posterior portion of the vertebral body of T5 are also evident. The angular kyphotic deformity of the spine and the presence of epidural inflammatory tissue lead to narrowing of the spinal canal and compressive myelopathy ����������������������������������������������������������������������������� 365 Fig. 12.20 Tuberculous spondylodiscitis. Sagittal T1-WI (first image), T2-WI (second image), STIR image (third image), and post-gadolinium T1-WI (fourth image) demonstrate reduced height and abnormal signal intensity of the intervertebral disc of T12-L1, with disappearance of the cortical bone of the adjacent endplates and partial collapse of the vertebral bodies, mainly of T12. Large discontinuous abscesses are seen in the prevertebral and paravertebral soft tissues of the thoracic and lumbar segments, as well as in the anterior epidural space, predominantly hypointense on T1-WI and heterogeneous on T2-WI, with peripheral post-contrast enhancement. The epidural abscess leads to spinal cord compression and extends from T10 to L4. The fifth image is a coronal post-gadolinium T1-WI that demonstrates large bilateral abscesses of the iliopsoas muscles������������������������������������������������������� 366 Fig. 12.21 Radiographs of the lumbar spine of a young child with spondylolysis of L5, more evident in the lateral view (last image), and slight anterior spondylolisthesis. Mild hypoplasia of this vertebral body is also present, as well as spina bifida occulta in L5 and S1. Interestingly, the bone defect is less evident in the oblique views, probably due to superposition of colonic gas������������������������������������������������������������������������������� 367 Fig. 12.22 Anteroposterior (a) and lateral (b) views of the lower lumbar spine of an adolescent with low-back pain. A dysplastic left lamina of L5 can be seen in the anteroposterior view, while the lateral radiograph reveals a bony defect of the pars interarticularis, as well as mild posterior wedging of the corresponding vertebral body and grade I anterior spondylolisthesis������������������������������������������������������������������������������������������������� 367 Fig. 12.23 CT of an adolescent with chronic lombalgia. In (a), transverse image reveals bilateral and symmetric bony defects with sclerotic borders in the vertebral arch of L5. Reformatted sagittal images (b) are more useful in disclosing the lesions, putting into evidence their corticated edges, which are indicative of chronic evolution (compare the isthmi of L5 with the normal ones in the vertebrae above). Spondylolisthesis is absent ����������������������������������������������������������������������������������������������������������������� 368 Fig. 12.24 Transverse CT image (a) and oblique sagittal reformatted image (b) of the lower lumbar spine of a male adolescent judo player complaining of subacute lumbar pain reveal incomplete and unilateral right-sided spondylolysis of L5, involving only the inferior cortex and not associated with spondylolisthesis. In (c), lateral radiograph (left), reformatted sagittal CT image (center), and sagittal fat sat T2-WI (right) of the lumbar spine of a 10-year-old male disclose incomplete left-sided spondylolysis of L5, which is quite obvious on CT; the radiograph discloses a faint lucent line that is difficult to characterize as a spondylotic defect, while MRI is the only imaging method able to reveal bone marrow edema in the neural arch extending to the vertebral body, even though the bone defect itself is not well demonstrated��������������������� 369

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Fig. 12.25 Male adolescent complaining of low-back pain of chronic evolution, with exacerbation in the last 10 days. In (a), transverse T1-WI (left) and T2-WI (right) display increased signal intensity on both sequences in the bone marrow of the right pedicle of L5, representing fatty replacement. On the other hand, there is low signal intensity on T1-WI and high signal intensity on T2-WI in the left pedicle, related to bone marrow edema. Sagittal STIR images (b) demonstrate hypointensity of the bone marrow of the right pedicle of L5 (first image) and hyperintensity in the left pedicle and in the ipsilateral facets (second image), mirroring the findings of (a). The left inferior articular facet of L4 and the ipsilateral superior articular facet of S1 also exhibit bone marrow edema. A small amount of fluid is seen in the right facet joint in L4–L5 and in the left ones in L4–L5 and L5–S1, with diffuse edema of the soft tissues adjacent to the latter. Complete bone defects can be seen in the isthmi of L5, much less conspicuous than those seen on CT images in previous figures. MRI findings are compatible with bilateral spondylolysis of L5, with a chronic lesion on the right side and an acute fracture on the left������������������������������������������������������������������������������������� 370 Fig. 12.26 3D gradient-echo sequence with sagittal reformatted images at the level of the facet joints of L5 (the same patient as in Fig. 12.25). The bony defects are much more evident in this sequence: note the irregular borders of the right-sided spondylolysis (first image), typical of chronic lesions, in contradistinction to the comparatively smoother borders of the acute left-sided defect (second image)��������������������������������������������������������� 371 Fig. 12.27 Sagittal T1-WI (upper row) and T2-WI (lower row) of the lumbar spine. There is a left-sided spondylolysis of L5 associated with grade I spondylolisthesis leading to ipsilateral foraminal narrowing and stretching of the emerging nerve root. The bony defect presents corticated borders, and fatty replacement is seen in the adjacent pedicle, which are indicative of chronic evolution��������������������������������������������� 371 Fig. 12.28 Transverse T2-WI at the level of L5 in a patient with spondylolysis and spondylolisthesis. The bony defects appear as transversely oriented clefts that interrupt the vertebral arch, with anterior translation of the vertebral body and exposure of the disc immediately below (“pseudobulging”). There is also narrowing of both foramina, mainly on the left ����������������������������������������������������������������������������������������������������������� 372 Fig. 12.29 Sagittal (a) and parasagittal (b) T1-WI and T2-WI of the lumbar spine of an adolescent demonstrating spondylolysis of L5 with grade II spondylolisthesis and marked foraminal stenosis in L5–S1. Hypoplasia and posterior wedging of the body of L5 are present, along with reduced height and low signal intensity of the intervertebral disc of L5–S1 and edematous changes of the bone marrow of the contiguous endplates. Stretching of the emerging nerve roots and osteodiscal changes related to abnormal vertebral mobility are the probable causes of pain in this patient������������������������������������������������������������������������������������������� 372 Fig. 12.30 Radiographs (a) and sagittal reformatted CT images (b) of the thoracic spine of an adolescent with Scheuermann disease. Thoracic kyphosis is present, related to anterior wedging and reduced height of the vertebral bodies from T7 to T9. The endplates are irregular, presenting subchondral sclerosis from T6 to T11. In (c), coronal and sagittal reformatted CT images and volume-rendered 3D reconstruction of the thoracic spine of a 13-year-old male with Scheuermann disease disclose mid-thoracic kyphosis and marked irregularity of the endplates

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of the middle and inferior thoracic vertebrae, the latter also present in the upper lumbar levels. Anteroposterior elongation of the apical vertebral bodies and disc space narrowing are present in both patients������������� 373 Fig. 12.31 Male adolescent with mild form of Scheuermann disease. Lateral radiograph (left) and sagittal reformatted CT image (right) demonstrate findings similar to those observed in the patients of Fig. 12.30 from T9 to T12; nonetheless, in spite of wedging and reduced height of the vertebral bodies of T9, T10, and T12, no significant kyphosis is present����������� 374 Fig. 12.32 MRI of the same patient of Fig. 12.31, sagittal T2-WI (a), and post-­ gadolinium fat sat T1-WI (b). In addition to the previously described findings, there is reduced height of the discs in the affected segment, with loss of the normal signal intensity on T2-WI, as well as minimal subchondral enhancement adjacent to the endplates of T8 and T9��������������������� 375 Fig. 12.33 Lateral radiograph of the cervical spine of a young child (a) reveals a calcified nodule with irregular contours in the anterior portion of C3– C4 disc space and mild sclerosis of the superior endplate of C4, with debatable increased density posteriorly to the abovementioned disc space. In (b), axial, reformatted sagittal and volume-rendered CT images disclose, in addition to the aforementioned findings, a large calcified oval-shaped nodule adjacent to the midline (paramedian left) posterior to C3–C4, deep to the posterior longitudinal ligament, corresponding to herniation of the disc calcification ����������������������������������������� 376 Fig. 12.34 Anteroposterior view of the lower thoracic spine of a 12-year-old boy (left) reveals nodular calcifications in the T10–T11 and T11–T12 disc spaces. Sagittal T1-WI (center) and T2-WI (right) show the nodules as areas of low signal intensity in all sequences in the posterior portions of both discs, as well as a small subligamentous herniation posterior to T11. Both discs present lower-than-normal signal intensity on T2-WI (disc dehydration)����������������������������������������������������������������������������������������������� 377 Fig. 13.1 Radiographs of the wrists of an adolescent with bilateral Madelung deformity. These images show medial inclination of the distal articular surfaces of the radii, with a notch in the distal medial portion of these bones at the origin of the Vickers ligament, bilaterally. Note the wedge-shaped configuration of the bones of the proximal carpal rows, allowing them to conform to the altered shape of the distal epiphyses of the forearms. The distal radial epiphyses appear triangular��������������������������� 380 Fig. 13.2 Coronal T1-WI and fat sat T2-WI (a) and sagittal fat sat T2-WI (b) of the left wrist of a patient with Madelung deformity. The typical appearance of the distal radius is quite evident, with medial and volar angulation of the articular surface. The Vickers ligament appears as a band of low signal intensity in both sequences tethering the triangular fibrocartilage complex and the lunate bone to the deformed radial epiphysis. A skin marker can be seen adjacent to the ulnar styloid, indicating a palpable lump due to dorsal subluxation of the distal ulna������������� 380 Fig. 13.3 Radiographs of the lower limbs of different patients with PFFD demonstrating the varied degrees of severity that this condition may present. In (a), both acetabula are markedly dysplastic, with no signs of ossification of the left femur and ipsilateral thigh shortening; the ipsilateral fibula is also malformed. The right femora are shortened in figures (a) and (b), presenting tapered and pointed proximal ends, notably in the latter image, which also displays ipsilateral acetabular dysplasia, cranial migration of the femoral diaphysis, and absence of the right fibula. In (c), there is symmetric and bilateral varus deformity

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of both femora, with mildly shallow acetabula and cone-shaped femoral heads. Figure (d) shows shortening and subtrochanteric varus deformity of the right femur, with acetabular dysplasia and reduced size of the ipsilateral femoral head; the right fibula is absent����������������������������� 381 Fig. 13.4 In the upper image, a pelvic radiograph reveals shortening and bending of both femora, with bilateral metaphyseal irregularity. The acetabula are reasonably well-formed, an indirect sign of the presence of the femoral heads. However, as the epiphyseal cartilages are not yet ossified, this study is unable to provide accurate information about them. Conventional arthrograms (lower image) delineate the contour of the femoral epiphyses, confirming that they are really present within the acetabula������������������������������������������������������������������������������������������������������� 382 Fig. 13.5 Pelvic radiograph (a), coronal T1-WI (b, upper row), and postgadolinium fat sat T1-WI (b, lower row) of the hips of a child with PFFD. The radiograph shows left-sided deficient development of the femoral head and neck, with ipsilateral varus deformity; there are also sclerosis and irregularity of the right proximal femoral metaphysis. MRI demonstrates that the provisional calcification zone is present on the right side, seen as a metaphyseal line of low signal intensity, and ill-­defined on the left side����������������������������������������������������������������������������������� 382 Fig. 13.6 In (a), radiograph of the left hip of a child with DDH shows joint incongruity, with a shallow and dysplastic acetabulum associated with a dysmorphic and laterally subluxated femoral head. In (b), pelvic radiograph of a 28-year-old female with late-stage sequelae of bilateral DDH shows bilateral coxa vara and posterosuperior dislocation of the femoral heads, which are markedly deformed. Both acetabula are poorly developed������������������������������������������������������������������������������������������������� 383 Fig. 13.7 Pelvic radiographs of two distinct patients with DDH. Shenton’s line is broken in both hips in (a), with mild lateralization of the right metaphysis and ipsilateral acetabular hypoplasia. In (b), the right hip shows evidence of frank dislocation, with cephalic migration of the femur and hypoplasia of the acetabulum; discontinuity of Shenton’s line is seen in the left hip, as well as mild acetabular hypoplasia. The real position of the femoral heads can be only inferred on radiographs, as they are not yet ossified ��������������������������������������������������������������������������������� 384 Fig. 13.8 Right-sided DDH. Pelvic radiographs reveal that the ossified portion of the right femoral epiphysis is smaller and presents delayed development if compared to the contralateral one. The right epiphysis is situated outside the inferomedial quadrant delimited by the intersection of Perkins’ and Hilgenreiner’s lines. Shenton’s line is clearly discontinuous on the right, with hypoplasia of the ipsilateral acetabulum ��������������������������������������������������������������������������������������������������������� 384 Fig. 13.9 In (a), US of the left hip of a newborn reveals normal values for the angles measured with Graf’s static method (see text). In (b), DDH is present, with reduction of the alpha angle and increase of the beta angle������������������������������������������������������������������������������������������������������������������� 385 Fig. 13.10 In (a), even though marked acetabular hypoplasia and asymmetric growth of the femoral heads are clearly seen, the radiograph is unable to provide an accurate evaluation of how successful was closed reduction of hip dislocation after cast placement. Reformatted CT images (b) and volume-rendered reconstruction (c) of a distinct patient who underwent a similar procedure display the articular relations in a

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safe and noninvasive way; left-sided hypoplasia of the acetabulum and of the femoral head is present, more evident in (c)��������������������������������������������� 385 Fig. 13.11 Radiographs (upper row) and CT images (lower row) of two distinct patients with DDP demonstrates similar findings: a well-­defined cortical defect in the superolateral portion of the articular surface of the patella, with subtle depression of the overlying cartilage on CT. (Courtesy of Dr. Pablo Coimbra, MD, Uniclinic Diagnóstico por Imagem UDI and Clínica Trajano Almeida, Fortaleza, Brazil) ������������������������� 386 Fig. 13.12 Transverse CT image (a, left) and fat sat T2-WI (a, right) of the right knee of the same patient with DDP. There is bone sclerosis adjacent to the cortical defect, more evident on CT, as well as thinning of the articular cartilage, whose signal intensity is heterogeneous on MRI. In a different patient, axial fat sat T2-WI of the left knee (b) shows a well-defined DDP in which the signal intensity within the defect is similar to that of the overlying articular cartilage, whose internal signal is mildly hyperintense����������������������������������������������������������������������������������������� 386 Fig. 13.13 CT of the left knee of an 11-year-old male with recent TPLD (images in the transverse (a), coronal and sagittal planes (b) and volumerendered reconstructions (c) and (d)). The transverse images display joint effusion and an osteochondral loose body in the lateral recess of the suprapatellar pouch, as well as marked trochlear dysplasia and lateral subluxation of the patella. In addition to the aforementioned findings, reformatted images and volume-rendered reconstructions reveal cortical irregularity along the anterior aspect of the lateral femoral condyle (donor site of the osteochondral fragment, avulsed during an episode of patellofemoral instability)������������������������������������������������� 387 Fig. 13.14 Transverse CT image (a) and volume-rendered reconstruction (b) of the left knee of an adolescent with chronic patellofemoral instability and recurrent patellar dislocation. The trochlea is shallow, associated with patellar tilt and subluxation. There is also a small avulsed bone fragment adjacent to the site of insertion of the medial patellar retinaculum, as well as irregularity of the adjacent cortex. In (c), in addition to the dysplastic patellofemoral abnormalities, transverse CT images disclose irregular cortical contours of the medial pole of the patella and avulsed bone fragments in the adjacent soft tissues������������������������� 389 Fig. 13.15 Transverse fat sat T2-WI of the right knee of an adolescent with a recent episode of lateral patellar dislocation. Typical “kissing contusions” with bone bruises are seen in the medial patellar margin and in the outer surface of the lateral femoral condyle, in addition to joint effusion and a small popliteal cyst. Partial tear of the medial retinaculum, adjacent to its patellar insertion, can be seen in (a). There is an osteochondral lesion on the medial facet of the articular surface of the patella, more evident in (a), with detachment of a hypointense osteochondral fragment that is anteriorly situated relative to the distal segment of the anterior cruciate ligament in (c). In (d), similar findings are seen in transverse T2-WI of a 14-year-old boy: extensive cartilaginous damage is present, with formation of a chondral flap, as well as a depressed cortical fracture along the external surface of the lateral femoral condyle and marked patellofemoral incongruity����������������������� 390 Fig. 13.16 MRI of the left knee of a 13-year-old male with chronic patellofemoral instability and no recent episodes of dislocation. Transverse fat sat T2-WI reveal small joint effusion, trochlear dysplasia, and a subtle area of bone marrow edema in the lateral femoral condyle, reminiscent of a

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remote patellar dislocation occurred several months earlier. A small popliteal cyst is also present������������������������������������������������������������������������������� 391 Fig. 13.17 CT of the right knee of a 9-year-old girl with chronic patellofemoral instability. Transverse images (a) and volume-rendered reconstruction (b) display marked patellofemoral incongruity, with a convex trochlear surface and obvious lateral subluxation of the patella ��������������������������������������� 391 Fig. 13.18 US of the popliteal fossa of a patient with juvenile idiopathic arthritis. There is a popliteal cyst with its characteristic “beak” pointing to the space between the medial gastrocnemius and the semimembranosus tendons. The cyst presents heterogeneous content, with synovial thickening and hyperemia on Doppler related to the subjacent arthritis. (Courtesy of Dr. Maria Montserrat, MD, Clinica Montserrat, Brasilia, Brazil)����������������������������������������������������������������������������������������������������������������� 391 Fig. 13.19 Popliteal cyst in the right knee of a 7-year-old male. Transverse fat sat T2-WI (a) and sagittal T1-WI and PD-WI (b) demonstrate a cystic lesion in the soft tissues of the popliteal fossa, with the typical beaklike projection pointing to the interval between the medial gastrocnemius and the semimembranosus tendons. Intracystic septa can be seen, usually deprived of significance. In (c), axial PD-WI of a different patient shows the typical communication of the cyst with the joint through a neck between the tendons of the medial gastrocnemius and semimembranosus ��������������������������������������������������������������������������������������� 392 Fig. 13.20 An 11-year-old boy with pain and a clicking sensation on the lateral compartment of his left knee. Anteroposterior view (a) reveals widening of the lateral joint space, with hypoplasia of the lateral tibial spine and of the lateral femoral condyle. Sagittal T1-WI (b) demonstrate continuity across the anterior and posterior horns of the lateral meniscus (“bow-tie” appearance) in three contiguous slices, while coronal fat sat PD-WI (c) show increased meniscal dimensions covering the full extent of the articular surface of the corresponding tibial plateau. Discoid meniscus������������������������������������������������������������������������� 392 Fig. 13.21 Tear of a discoid meniscus associated with parameniscal cyst in a child. Sagittal T2-WI (upper row) and fat sat PD-WI in the coronal and axial planes (lower row) show a discoid meniscus whose configuration is similar to that seen in Fig. 13.20. However, in the present case, there is a horizontal tear extending from the posterior horn to the anterior horn, in addition to a heterogeneous parameniscal cyst protruding to the adjacent Hoffa fat pad����������������������������������������������������������������������������������������� 394 Fig. 13.22 An 11-year-old boy with pain in the lateral compartment of the left knee and limited range of motion. Sagittal T1-WI and T2-WI (upper row) and coronal PD-WI and fat sat PD-WI (lower row) reveal an incomplete discoid meniscus presenting a horizontal tear, with a small parameniscal cyst protruding laterally ��������������������������������������������������������������� 394 Fig. 13.23 Anteroposterior views of the knees of a child with left-­sided Blount disease. There is varus deformity of the left proximal tibia, with “beaking” of the medial portion of the corresponding metaphysis and hypoplasia of the medial tibial plateau. The medial tibial physis is widened and irregular, with thickening of the adjacent diaphyseal cortex������������������������������������������������������������������������������������������������������������������� 395 Fig. 13.24 Coronal reformatted CT images (a) and volume-rendered reconstructions (b) of the left knees of a 7-year-old male (left) and an 8-year-old girl (right) with Blount disease. Both children present varus deformity of the proximal tibiae, with medial slope and hypoplasia of

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the medial plateaus and “beaking” of the medial portion of the metaphyses, more pronounced in the younger individual, who also presents medial physeal narrowing and cortical thickening in the adjacent diaphysis. Widening and irregularity of the medial physis are present in the female patient������������������������������������������������������������������������������� 396 Fig. 13.25 Coronal gradient-echo images of the left knee of a child with Blount disease. The imaging findings are quite similar to the radiographic picture described in Fig. 13.23. Nevertheless, MRI is more accurate for physeal assessment (notice the peripherally located medial transphyseal bone bridge) and in the evaluation of structures that are not detectable on radiographs, such as the epiphyseal cartilage (which is thicker in the medial tibial plateau if compared to the lateral) and the menisci (notice the dysplastic appearance of the medial meniscus, which is enlarged and shows abnormal signal intensity) ����������������������������������� 397 Fig. 13.26 Transverse CT image (a) and oblique view (b) of the forefeet of two distinct adolescents with Freiberg disease. In (a), there are collapse and fragmentation of the articular surface of the head of the second metatarsal, as well as remodeling of the adjacent articular surface of the proximal phalanx. In (b), advanced disease is found in the third metatarsal head, with marked bone collapse and prominent remodeling of the base of the proximal phalanx������������������������������������������������������������������� 397 Fig. 13.27 Axial views of both calcanei in a patient with bilateral talocalcaneal coalition. The middle facets are obliquely oriented and narrowed, with irregularity of the joint surfaces. The sustentaculum tali and the adjacent talus are deformed, bilaterally ������������������������������������������������������������� 398 Fig. 13.28 Lateral (a), oblique and anteroposterior (b) views of the left ankle of a child with calcaneonavicular coalition. The lateral view shows that the anterior process of the calcaneus is abnormally elongated and tubular (“anteater sign”), as well as a small dorsal talar “beak.” The coalition can be seen in the oblique view, with lateral prominence of the navicular bone. Both the lateral portion of the navicular and the anterior calcaneal process are irregular, with bone fragmentation adjacent to the articular surfaces. The lateral prominence of the navicular is also evident in the anteroposterior view, as well as loss of the normal alignment usually seen between this bone and the talar head ��������� 399 Fig. 13.29 Lateral view of the right ankle of a 19-year-old male showing indirect signs of talocalcaneal coalition. The “C sign” is present, as well a large talar beak������������������������������������������������������������������������������������������������������������� 399 Fig. 13.30 Lateral radiographs of the ankles of an adolescent with bilateral talocalcaneal coalition. The same findings present in the patient of Fig. 13.29 are seen, with some variations. There is bone fragmentation associated with the talar beak in the right ankle, while the “C sign” is discontinuous on the left side in its posterior portion����������������������������������������� 399 Fig. 13.31 Transverse CT image (a), coronal reformatted image (b) and volumerendered reconstructions (c) of the ankles of an 11-year-old male with non-ossified talocalcaneal coalition on the left. Compare the normal anatomy of the right subtalar joint with the abnormal contralateral side. There is hypoplasia of the left sustentaculum tali, with loss of its typical polyhedral appearance, as well as enlargement of the adjacent talus. Both bones show rounded contours, with narrowing of the corresponding joint space, irregular articular surfaces, and mild subchondral sclerosis ����������������������������������������������������������������������������������������� 400 Fig. 13.32 Imaging evaluation of the left ankle of an 8-year-old boy with talocalcaneal coalition. A lateral radiograph (a) shows flattening of the

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plantar arch and absence of the image corresponding to the middle facet. Figure (b) and (c) compare CT (left images) and MRI (right images) sections obtained in similar levels in the transverse and coronal planes. Even though the coalition is well demonstrated on both studies, CT is superior in delineating bone anatomy, while MRI has the unique ability to reveal subchondral bone marrow edema. In (d), sagittal T1-WI (upper image) and fat sat T2-WI (lower image) show low signal intensity in the involved joint space in both sequences, which is typical for fibrous coalition ����������������������������������������������������������������� 400 Fig. 13.33 Sagittal reformatted CT images (a) and volume-rendered reconstruction (b) of the same foot as in Fig. 13.28. The previously described findings are depicted with superior anatomic detail. Although the coalition is clearly non-ossified, it is not possible to determine if it is fibrous or cartilaginous in nature with CT. In another patient, MRI of the left ankle of a 12-year-­old male (axial and sagittal T1-WI and fat sat T2-WI in c and d) disclose findings similar to those of images (a) and (b) and, in addition, adjacent bone marrow edema and a band of low signal intensity in all sequences interposed between the anomalous osseous surfaces, characterizing a fibrous calcaneonavicular coalition������������� 401 Fig. 13.34 Transverse CT images (a) and volume-rendered reconstruction (b) of the left ankle of a child with osseous talocalcaneal coalition. There is a bony bridge in the middle facet of the subtalar joint, with seamless continuity of the cortices and of the cancellous bone of the talus and of the calcaneus������������������������������������������������������������������������������������������������������� 402 Fig. 13.35 Bilateral extra-articular talocalcaneal coalitions posterior to the middle talocalcaneal joints can be seen on a CT scan of an 8-year-­old male. Transverse (a), coronal (b), and sagittal (c) reformatted images and volume-rendered reconstruction (d) reveal findings similar to those above described for non-ossified coalitions: narrowed joint spaces, irregularity of the articular surfaces, hypertrophy of the articular margins, and subchondral sclerosis��������������������������������������������������������������������� 403 Fig. 13.36 CT scan of a 17-year-old adolescent with calcaneonavicular coalition. Transverse (a), reformatted sagittal (b) images, and volume-­rendered reconstructions (c) clearly demonstrate the abnormal anatomy, particularly the elongated anterior process of the calcaneus, which have a polyhedral appearance on 3D images (“anteater sign”). Nevertheless, just like in Fig. 13.33, though is quite obvious that the coalition is non-ossified, CT alone cannot define if it is fibrous or cartilaginous. However, sagittal T1-WI and fat sat T2-WI (d) and transverse T1-WI (e, left) and T2-WI (e, right) show signal intensity similar to that of cartilage within the coalition (hypointense on T1-WI and hyperintense on T2-WI), establishing the cartilaginous nature of the lesion. In (d), bone marrow edema is evident in the anterior calcaneal process, in addition to fluid within the tarsal sinus and in the tibiotalar joint ��������������������� 403 Fig. 13.37 Radiographs of a child with SED. In (a), there is bilateral and symmetric deformity of the femoral heads, which are flattened and widened, as well as remodeling of the acetabula and bilateral coxa vara. Platyspondyly is evident in radiographs of the thoracolumbar spine (b), as well as reduced height of the disc spaces and deformity of the vertebral endplates. Findings are more prominent in the dorsal spine ������������������������������������������������������������������������������������������������������������������� 404 Fig. 13.38 Radiographs of the thoracolumbar spine (a), pelvis (b) and knees (c) of a child with SED. Spinal changes similar to those described in Fig. 13.37 are seen, with most extensive involvement of the lumbar

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spine in this patient. The epiphyses of the proximal femora are deformed, with coxa vara, marked acetabular dysplasia, and bilateral coxofemoral subluxation. Anteroposterior view of the knees displays abnormal morphology of all epiphyses, with overgrowth of the medial femoral condyles and bilateral valgus deformity, as well as generalized metaphyseal widening. In (d), sagittal T2-WI and T1-WI of the lumbar spine of a young adult with SED tarda disclose hump-shaped mounds of bone in the central and posterior portions of the vertebral endplates, which present irregular contours, and anterior vertebral beaking, as well as diffuse reduction of the height and of the signal intensity of the intervertebral discs ��������������������������������������������������������������������������������������������� 406 Fig. 13.39 In this child with SED, radiographs of the thoracolumbar spine (a) show the typical vertebral deformity seen in previous patients. The height of the intervertebral disc spaces is relatively preserved because this is a young child. Pelvic radiograph (b) reveals bilateral coxa vara and fragmentation of the proximal femoral epiphyses. Epiphyseal fragmentation is also seen in the distal femur, involving the medial femoral condyle (c), with deformity of the proximal tibial epiphysis and metaphyseal widening��������������������������������������������������������������������������������� 407 Fig. 13.40 Scanogram of a patient with MED. There are bilateral and symmetric morphologic abnormalities involving the hips, knees, and ankles. Marked flattening of the femoral heads and condyles is present, as well as irregularity of the tibiotalar articular surfaces, with spheroid appearance of the talar domes and remodeling of the distal tibiae (ball-­in-­socket configuration)����������������������������������������������������������������������������� 408 Fig. 13.41 Radiographs of the pelvis (a) and of the knees (b) of a child with MED. The proximal femoral epiphyses have a stippled, mulberry-­like appearance, with bilateral coxa vara. Symmetric and bilateral varus deformities of the knees are also present, with malformed epiphyses and metaphyseal widening��������������������������������������������������������������������������������� 408 Fig. 13.42 Multiple skeletal abnormalities in a child with MED. In (a), there is bilateral and symmetric flattening of the femoral heads. Altered epiphyseal morphology is also seen in the distal femora and in the proximal tibiae in (b), with heterogeneous ossification and flattening of the articular surfaces. There is epiphyseal flattening of the metatarsal (c) and metacarpal (d) bones; morphologic abnormalities can be seen in the epiphyses of the first toes and in the distal radius and ulna. In (e), marked irregularity of the epiphyses in the right tibiotalar joint is evident, with incongruity of the joint surfaces. The secondary ossification centers of the capitula appear fragmented in (f), notably on the left side, with sclerosis of the fragments on the right����������������������������������� 409 Fig. 13.43 Fragmentation and flattening of the femoral heads in MED may closely resemble Legg-Calvé-Perthes disease, as seen in these radiographs. However, bilateral involvement of the epiphyses of several joints at the same time allows a safe differential diagnosis in most cases����������������������������� 410 Fig. 13.44 Pelvic radiograph (a) and MR-arthrography of the left hip (b) of an adolescent with MED. Radiographic findings include marked deformity of the femoral heads and bilateral coxa vara. Despite the irregularity of the epiphyses and the apparent incongruity of the hips on the radiograph, MR-arthrography demonstrates that the cartilaginous component of the joints is preserved, with smooth contours. Nevertheless, premature osteoarthritis must be kept in mind as a frequent complication of MED ������������������������������������������������������������������� 410

List of Figures

1

Imaging Methods and the Immature Joint: An Introduction

1.1

Introduction

Unparalleled improvements in diagnostic imaging have occurred over the last several decades. Until the 1960s, radiographs were the only technique available in this field. In time, however, more sophisticated imaging methods were gradually added to the diagnostic arsenal, and even radiographs have entered into the digital arena. Each of these imaging methods has singularities to be considered in the assessment of immature joints, and both the radiologist and the requesting physician must be familiar with them. The requesting physician is supposed to have an open-minded and receptive attitude, consulting with the radiologist whenever a doubt arises (e.g., “which imaging method is the most appropriate for this patient in this specific clinical setting?”) and providing all the relevant information for each case. Accordingly, the radiologist must perform the requested imaging study and interpret the findings under the light of the clinical picture. Analyzing the images without taking the clinical background into account is dangerous and may lead to an erroneous  – and potentially catastrophic  – diagnosis. This chapter is a brief introduction to the most important imaging methods used in the investigation of the immature joint, emphasizing their peculiarities in pediatric patients. It is important to keep in mind these imaging methods are complementary instead of exclusive, acting synergistically when properly combined.

1.2

Radiographs

Radiographs have always been closely associated with the assessment of the locomotor apparatus and its disorders. It is emblematic that the first radiographic study ever made was the image of a hand, the left hand of the wife of Wilhelm Röntgen, the discoverer of the X-rays, in 1895. In its classic form, currently dubbed “conventional” radiography, a radio-

graphic film is placed inside a cassette with intensifying screens and exposed to X-rays. The anatomic structure under study is interposed between the source of the radiation and this cassette. The resulting image translates the different densities of the several body tissues: denser tissues, such as the bone, appear whiter as they absorb the radiation in a higher degree, therefore limiting the amount that effectively reaches the film. Similarly, less dense tissues, such as fat, appear darker. Even though digital radiographs  – either obtained with computed radiography (CR) or digital radiography (DR) – take advantage of the same physical principles, they do not rely on X-ray films to produce medical images. On the contrary, a sensor receives the emitted radiation and transmits the electronically obtained information. The generated image is, in fact, a computer file, which can be viewed on a screen, archived in many types of digital media, or printed (either on paper or on medical imaging film). Despite the advantages of digital radiography over conventional radiography (wider dynamic range, less exposure to radiation, telemedicine capabilities  – Fig.  1.1), the training and the experience of the observer are far more important than the technology involved. Digital radiographs have become widely accessible in recent years and conventional radiographs are rarely seen nowadays in the authors’ daily practice. The notion that X-rays became outdated after the advent of modern imaging methods has no grounds. Radiographs remain essential and consist the first line of investigation for patients with articular disorders; as a general rule, radiographs must be available before requesting any additional imaging study (Fig. 1.2). They are inexpensive, widely available, and not operator-dependent and present good reproducibility. Furthermore, correct interpretation of imaging studies like ultrasonography and magnetic resonance imaging relies largely on correlation with radiographs. Two or more views are usually obtained, making it easier to determine the location of abnormal findings. In arthritic patients, radiographs

© Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_1

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1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.1  Radiographs of the left foot of a child performed with conventional (left) and digital (right) techniques. The digital radiograph has wider dynamic range when compared to the conventional one: the toes and the tarsal bones are equally well seen on the former, while only the middle portion of the foot is adequately exposed on the latter

are obtained early in the clinical course in order to rule out traumatic or orthopedic conditions. Furthermore, serial radiographs may demonstrate the progression of joint damage in articular disease, and radiographic findings are used as imaging criteria in several staging and scoring systems, as they are very suitable for demonstration of established osteoarticular damage (e.g., cortical erosions, abnormal joint alignment, joint space narrowing and ankylosis – Fig. 1.3). Moreover, radiographs are often problem-solving on their own, as several musculoskeletal disorders can be readily diagnosed on X-rays (e.g., bone tumors, fractures, osteomyelitis, congenital malformations, and developmental abnormalities – Figs. 1.4 and 1.5). Disadvantages include the use of ionizing radiation (which is especially deleterious for the immature organism), low sensitivity for the early stages of

articular diseases, and limited usefulness in the assessment of the soft tissues and anatomically complex joints. Once-­ popular radiographic techniques such as conventional arthrograms and linear tomography (planigraphy) became virtually obsolete after the advent of cross-sectional imaging, given the higher diagnostic accuracy and the noninvasive nature of the latter (Fig. 1.6).

1.3

Ultrasonography

Ultrasonography (US) has become widely accepted for joint assessment, notably after the introduction of highfrequency transducers. In US, an array of piezoelectric crystals generates a beam of ultrasonic waves that is

1.3 Ultrasonography

Fig. 1.2  Radiograph of the right knee of a 13-year-old female with juvenile idiopathic arthritis diagnosed 1 year earlier. Even though erosions are absent, osteoporosis and subtle increase in the size of the epiphyses are already seen, related to the hyperemic state. This radiograph will serve as a baseline study to monitor disease evolution and treatment response

Fig. 1.3  Pelvic radiograph of a 22-year-old male with juvenile idiopathic arthritis since age 15. There is advanced arthritis of the left hip, with regional osteoporosis, erosions of the articular surfaces, narrowing of the joint space, and reduced size of the ipsilateral femoral head, which is markedly deformed

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directed to a given structure, which will reflect them in different degrees depending on the composition of the tissues. For example, the synovial fluid is a very good conductor of ultrasonic waves, while the cortical bone reflects them almost entirely. The reflections of the ultrasonic beam are transmitted to a computer that will process the obtained data and produce real-time images on a screen, therefore providing a unique dynamic characteristic to US. Although excellent for the evaluation of large joints and superficial soft tissues (Figs. 1.7 and 1.8), this imaging modality presents limitations in the assessment of deeply seated structures and small and/or deformed joints, to which the transducer may not fit satisfactorily. In small children, “hockey stick” transducers allow the examination of regions where conventional linear transducers would be too large. Furthermore, the ultrasonic beam relies on the existence of acoustic “windows” to reach the region of interest, which may not be present in the anatomic site under study. Superficially located osseous abnormalities may occasionally be detected on US, but essentially no information is gathered about the innermost portions of the bones. Doppler US (color Doppler and power Doppler) is a technique that detects and measures blood flow in vascular structures, being very useful in the investigation of hyperemic joint diseases, entheseal inflammation, soft-tissue masses, and fluid collections (Figs. 1.9, 1.10, and 1.11). US is also useful to evaluate the soft-tissue component of traumatic and sports-related musculoskeletal injuries. US is extensively used in pediatric patients because it is painless, inexpensive, and widely available, can be performed at the bedside, and does not require special or uncomfortable positioning. The absence of ionizing radiation must also be taken into account in this age group, as serial studies can be performed without risk of damage to the growing organism. It is well-tolerated by children and more than one joint can be examined expeditiously in a single session. Joint effusion and synovial thickening are readily apparent on US, as well as signs of inflammation within bursae, synovial sheaths, or cysts (Figs. 1.7, 1.9, and 1.12). The articular cartilage is particularly well seen in large joints (Fig. 1.12). In arthritic patients, the degree of hyperemia can be estimated with Doppler US and monitored in sequential studies, serving as an indicator of disease activity and a marker of treatment response. The dynamic properties of US allow for assessment of a given structure in different spatial planes (Fig.  1.7), evaluation of articular relationships (such as in newborns with suspected developmental dysplasia of the hip – Fig. 1.13) and real-time demonstration of abnormalities that would otherwise go unnoticed with other imaging methods, such as tendon dislocations or muscle hernias (Fig. 1.8). Additionally, US is very useful to guide invasive diagnostic and/or therapeutic procedures.

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1  Imaging Methods and the Immature Joint: An Introduction

a

b

Fig. 1.4  Radiographs of a child with short stature showing generalized increase in bone density, with loss of definition of the corticomedullary junction (a). The fingers are short and stubby, and the distal phalanges are hypoplastic (b). Craniofacial abnormalities include macrocrania,

trigonocephaly, parieto-occipital bossing, and straightening of the mandibular angles (c). These findings are typical of pyknodysostosis, with no need for additional investigation

1.3 Ultrasonography Fig. 1.4 (continued)

Fig. 1.5  In an appropriate clinical background, some radiographic patterns are almost pathognomonic. However, in most cases these findings usually appear late in the course of the disease, limiting their effectiveness for early diagnosis. In (a), there is a linear cortical lucency along the medial aspect of the proximal diaphysis of the right tibia associated with periosteal reaction and bone neoformation, which are highly suggestive of stress fracture in an adolescent runner. In (b), radiograph of a child with pain in the left hip shows that the femoral head is sclerotic and reduced in size, presenting a curvilinear subchondral lucency (crescent sign), findings typical of Legg-Calvé-Perthes disease. In both cases, MRI would be able to establish the diagnosis much earlier

5

c

a

b

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1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.6  Until the advent of modern imaging methods, only invasive radiographic procedures, such as conventional arthrograms (a), were able to demonstrate the epiphyseal cartilage, demanding sedation and intra-articular injection of iodinated contrast. This cartilage is much larger than the mineralized ossification nucleus (n), the only portion of the epiphysis that is detectable on radiographs. In (b), for comparison, coronal T1-weighted image (T1-WI, left) and fat sat T2-weighted image (T2-WI, right) of the left hip of a 3-year-old child are able to display both ossified and nonossified structures with high detail and in a noninvasive way, including the epiphyseal and articular cartilages, the acetabular labrum, muscles, and tendons

a

b

Despite its advantages, US has also some drawbacks, whose importance should not be underestimated. It has limited reproducibility and lacks standardized protocols, requiring specific training of the operator and a sound knowledge of the peculiarities of the immature skeleton (operator-­dependent method), besides demanding appropriate equipment, with high-frequency linear transducers (equipment-dependent method).

1.4

Nuclear Medicine

Scintigraphy is a generic name given to the majority of the nuclear medicine scans. During these studies, a radiopharmaceutical (substance formed by the combination of a radio-

nuclide and a pharmaceutical compound) is administered to the patient and, depending on its properties, it will build up in a given tissue or organ. Such buildup (which is most often due to increased metabolic activity) is registered by detectors in a gamma camera that processes the collected data and produces images based on the emitted pattern of radiation. The different radiopharmaceuticals and techniques available are capable to assess several organs and systems. Whole-body bone scan with technetium-99m compounds is the most important scintigraphic study in musculoskeletal imaging; other radionuclides are used less often, in specific clinical situations. Generally speaking, bone scintigraphy is a highly sensitive study that, if positive, usually indicates the presence of an abnormality, whose usefulness has been proved mostly in the fields of trauma, oncology, and musculoskele-

1.4 Nuclear Medicine

Fig. 1.7  US of two distinct children with juvenile idiopathic arthritis and tenosynovitis involving the flexor pollicis longus tendon in the first patient (left images) and the flexor carpi radialis in the second one (right images). The tendons are elongated on sagittal scans (left images and upper right image) and appear as round structures on transverse scans

Fig. 1.8  US of an adolescent complaining of a nodule of elastic consistency and variable dimensions in the lumbar region. The image reveals a focal defect of the lumbar aponeurosis measuring 12  mm (calipers) and herniation of paravertebral muscle fibers

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(lower right image), with a fibrillar appearance. The synovial fluid in the tendon sheaths appears hypoechogenic, while amorphous echogenic foci are related to synovial thickening and debris. Even a 4-year-­ old child (first patient) tolerates an US scan very well

tal infection (Fig. 1.14). On the other hand, however, besides exposing the immature organism to ionizing radiation, its specificity is very low, and it usually requires complementary imaging studies to clarify the real nature of an unexpected area of increased uptake (Figs. 1.14, 1.15, and 1.16). Furthermore, its spatial resolution is very poor, and sometimes it is not possible to determine the precise location of the affected area, such as when very intense carpal or tarsal uptake is found. In children, there is physiological uptake in the normal growth plates  – which are juxtaarticular and/or intra-­articular – and in the sacroiliac joints, limiting its usefulness even more (Fig. 1.16). A distinctive feature of bone scintigraphy is its ability to study the whole body in a single study, which is very useful, for example, in the screening of metastases or “silent” sites of involvement in multifocal skeletal diseases.

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1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.9  An 18-year-old female with autoimmune hepatitis since age 14 and taking immunosuppressant drugs presenting with left-sided pyogenic prepatellar bursitis. US scans (upper row) reveal thickening of subcutaneous tissue and filling of the prepatellar bursa with heterogeneous hypoechogenic material; peripheral hyperemia is seen on Doppler US (red-yellowish streaks in the second image). In the lower

row, T2-WI (first image) discloses subcutaneous thickening and distension of the prepatellar bursa by heterogeneous content, mostly hyperintense. Post-contrast fat sat T1-WI (second image) reveals enhancement of the synovium and of the inflamed subcutaneous tissue, corresponding to the hyperemic zones seen on Doppler US. The non-enhancing material inside the bursa corresponds to debris and pus

While “common” scintigraphies produce planar (two-­ dimensional) images, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are nuclear medicine techniques that produce three-­ dimensional information. PET and/or CT is a modality that blends images obtained with PET and those obtained with computed tomography. This study allows correlation of PET images, which are highly sensitive, with matching computed tomography images, which provide high anatomic resolution. Even though their utility in some pediatric ­musculoskeletal conditions is well established, the exact role of these modalities in most articular diseases is yet to be determined, especially considering the radiation burden delivered by PET and/or CT.

1.5

Computed Tomography

After the advent of computed tomography (CT) in the 1970s, this imaging method became widely popular and disseminated throughout the world. To put it briefly, in a modern scanner there are an X-ray tube and an array of detectors that rotate around a moving table, in which the patient is lying. Different tissues have different attenuation coefficients, producing contrast that is identified by the detectors. The three-­ ­ dimensional information thus obtained is hence ­processed, providing volumetric data to create medical images. Continuous technological progress has led to improved speed of acquisition and image quality in CT

1.5 Computed Tomography

Fig. 1.10  A 9-year-old boy presenting with a painless infrapatellar lump in the anterolateral aspect of the left knee. Doppler US (upper left image) discloses an oval well-delimited and heterogeneous hypoechogenic mass, with central areas of increased blood flow. Sagittal T1-WI (upper right image), transverse fat sat T2-WI (lower left image), and post-gadolinium fat sat T1-WI (lower right image) reveal a sharply

a

Fig. 1.11  Color Doppler (a) and power Doppler (b) US images of the right wrist of a patient with a presumptive diagnosis of palindromic rheumatism. Joint effusion and a thickened hyperemic synovium can be

9

delimited lesion with heterogeneous signal intensity, predominantly hypointense on T1-WI and hyperintense on T2-WI, whose epicenter is near the patellar tendon. There is marked post-gadolinium enhancement, as could be inferred from the increased flow seen on Doppler US. The histopathological diagnosis was fibroma of the tendon sheath

b

seen, with increased flow demonstrated on Doppler images, especially evident in (b)

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Fig. 1.12  US of a 5-year-old male with transient synovitis of the left hip disclosing synovial thickening and homogeneous synovial effusion. The growth plate and the epiphyseal cartilage are clearly seen as hypoechogenic structures

Fig. 1.13  Normal US scan of the right hip of a newborn with suspected developmental dysplasia. Both the femoral head and the acetabulum present preserved shape and size, and the articular relationships are normal (see Chap. 13)

s­canners, and multidetector computed tomography (MDCT) is currently the state-of-the-art in this imaging field. In MDCT, there is simultaneous acquisition of multiple slices at high speed, with unparalleled spatial resolution. These scanners are coupled to dedicated workstations that generate multiplanar reformatted images and volume-rendered reconstructions. CT is the best imaging modality for the assessment of bone anatomy, being capable to detect even very subtle abnormalities such as incomplete fractures, osseous avulsions, small foci of calcification, tiny cortical erosions, or faint periosteal reaction in exquisite detail (Figs. 1.15, 1.17, 1.18, 1.19, and 1.20). Radiographic findings can be

1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.14  Bone scintigraphy of a male adolescent with chronic osteomyelitis of the left femur showing markedly increased uptake in the distal two-thirds of this bone. Even though quite evident, this scintigraphic finding is not specific, and several other conditions could cause a similar pattern. Scintigraphy is most often performed either in individuals with an already diagnosed disease, in order to assess its activity, or in concert with other imaging modalities in the investigation of patients with uncertain diagnosis

d­ emonstrated earlier and more accurately with CT, notably in the evaluation of anatomically complex joints (Fig. 1.21). Multiplanar reformatted images and volume-rendered reconstructions are warmly welcomed by non-radiologists, as they usually find these images more familiar and easier to understand than transverse sections (Figs. 1.17, 1.18, 1.19, 1.20, 1.21, and 1.22). However, despite its high spatial resolution, CT has limited usefulness in the evaluation of the soft tissues, and its contrast resolution is lower when compared to magnetic resonance imaging (Fig.  1.18). Furthermore, CT scans deliver ionizing radiation in a non-negligible amount and should be used judiciously in children. Intravenous iodinated contrast is indicated for patients with inflammatory or infectious joint diseases, soft-tissue masses, fluid collections, and tumors and/or pseudotumors; nevertheless, CT is not recommended for assessment of disease activity in patients with chronic arthritis, as magnetic resonance imaging and US are the imaging methods of choice in this setting. CT-arthrography is a second-line procedure in pediatric radiology, performed after intraarticular injection of iodinated contrast, being useful in selected cases, such as in the assessment of chondral and/or osteochondral lesions (Fig. 1.23) or to detect non-­mineralized intra-articular loose bodies. Even though relatively rare, allergic reactions to iodinated contrast agents do occur, and the fact that these agents are potentially nephrotoxic must be kept in mind (the potential risk-to-benefit ratio should be carefully evaluated, especially in patients with impaired renal function). CT is not usually the first choice for imaging

1.5 Computed Tomography

a

Fig. 1.15  Bone scintigraphy revealing an area of increased uptake projected over the right frontal region (a). Though this finding is a reliable indicator of increased metabolic activity, it is far from being specific. CT of the head of the same patient (b) discloses a focal area of increased

a

11

b

bone density affecting the outer table and the diploe of the right half of the frontal bone showing the typical “ground glass” appearance of fibrous dysplasia. Compare the high spatial resolution of CT with the low level of anatomic detail obtained with bone scintigraphy

b

c

Fig. 1.16  Male adolescent with reactive arthritis. Bone scintigraphy (posterior view, a) shows increased uptake in the sacroiliac joints suggesting sacroiliitis, even though scintigraphic sacroiliac evaluation is particularly difficult in skeletally immature individuals; note the physiologic uptake in the distal physes of the forearms, which also occurs in

normal sacroiliac joints. Coronal STIR (b) and post-contrast fat sat T1-WI (c) reveals areas of subchondral marrow edema and small erosions along the articular surfaces of both sacroiliac joints, bilaterally, with post-gadolinium enhancement, establishing the presence of sacroiliitis beyond any doubt

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1  Imaging Methods and the Immature Joint: An Introduction

a

Fig. 1.17  Reformatted CT images (a) and volume-rendered reconstructions (b) of the left ankle of a healthy 12-year-old male illustrate the multiplanar capabilities of this method, its high spatial definition, and the capacity to highlight different body tissues, like the bones (upper row, b) and the tendons (lower row, b). In (c), transverse CT images suffice to demonstrate marked trochlear dysplasia and signs of

patellofemoral instability in a 12-year-old male, with a large osteochondral lesion in the anterior aspect of the lateral condyle and a displaced bone fragment in the intercondylar notch; nevertheless, volume-­ rendered reconstructions (d) are an elegant way to better display the patellofemoral abnormalities and the relation among the avulsed fragment and the adjacent structures

1.5 Computed Tomography

b

Fig. 1.17 (continued)

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1  Imaging Methods and the Immature Joint: An Introduction

c

d

Fig. 1.17 (continued)

1.6 Magnetic Resonance Imaging

15

Fig. 1.18  A 12-year-old male with a history of trauma in his left knee 1 month earlier, persistent pain, and normal radiographs. Coronal fat sat PD-WI (left) shows joint effusion and extensive bone marrow edema in the distal femoral metaphysis, acutely delimited by the growth plate. There is a questionable infraction of the lateral cortex, immediately above the physis, which is widened and hyperintense in its lateral por-

tion. Coronal reformatted CT image (right) demonstrates beyond any doubt the suspected fracture and the asymmetric physeal widening. Despite the adequacy of CT for bone assessment, this method has limited usefulness in the evaluation of the soft tissues (compare the level of detail of the intra-articular structures obtained with CT and MRI) and is completely insensitive for bone marrow edema

assessment in most pediatric patients with joint complaints, and US and magnetic resonance imaging are generally more appropriate for clarification of equivocal radiographic ­findings. In children, musculoskeletal CT is more useful in the assessment of traumatic joint injuries or as an alternative imaging method if magnetic resonance imaging is not available.

1.6

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is currently the most important imaging method in the assessment of the locomotor apparatus. During MRI scanning, the patient is positioned inside a magnet that generates a powerful magnetic field. A radiofrequency energy pulse is delivered to protons spinning

16

1  Imaging Methods and the Immature Joint: An Introduction

a

c

b Fig. 1.19  Transverse (a) and reformatted (b and c) CT images of the femur of a 16-year-old male with a diaphyseal osteoid osteoma. Even though the transverse image is sufficient to demonstrate the radiolucent

tumoral nidus and a tiny central calcification, the reformatted images are useful to put in evidence the marked cortical thickening, endosteal sclerosis, and diaphyseal bowing that are also present

1.6 Magnetic Resonance Imaging

17

Fig. 1.20  Axial transverse CT image (left image) and axial fat sat T2-WI (right image) at the level of the anterior inferior iliac spines (AIIS) of a 13-year-old boy. Even though avulsion of the apophysis of

the right AIIS is better demonstrated with CT because of its inherently superior spatial resolution, MRI can reveal edematous changes of the bone and soft tissues to which CT is insensitive

Fig. 1.21  Oblique reformatted CT images of a sessile osteochondroma (arrows) originating from the posterior surface of the body of the scapula in a 16-year-old female. CT is excellent for demonstration of cortical and medullary continuity between the osteochondroma and the parent bone, typical of this type of lesion. Furthermore, CT is also very

useful in this particular case because of the anatomically complex structure of the scapula – which would render the lesion difficult to see on radiographs – and because of its multiplanar capabilities, making possible to obtain reformatted images in any needed plane in order to better depict the exostosis

18

a

b

Fig. 1.22  Talocalcaneal coalition in an 11-year-old male. Sagittal reformatted CT images (a) are diagnostic, revealing narrowing of the joint space of the middle facet and irregularity of the joint surfaces, as well as sclerosis of the subchondral bone. Nevertheless, most of the non-radiologists will prefer volume-rendered reconstructions (b) to envision the anatomic abnormality

a

Fig. 1.23  Female adolescent with retropatellar pain in her left knee. CT-arthrography (a) reveals irregularity of the surface of the patellar cartilage with great detail (arrows), but it is limited for assessment of the cartilaginous substance. Transverse fat sat proton density-weighted

1  Imaging Methods and the Immature Joint: An Introduction

in a given frequency (mainly hydrogen protons, the most abundant in the human body), so that they align with the magnetic field. Once this pulse is stopped, protons turn back to their original random status and, by doing so, release a signal that is captured and processed to obtain medical images. Basic sequences include T1-weighted images (T1-­ WI, more useful to assess the anatomy of the region of interest) and T2-weighted images (T2-WI, more sensitive in the detection of abnormal findings, mostly when some form of fat suppression is used [fluid-sensitive sequences], such as fat saturation [fat sat], Dixon technique or short-tau inversion-­ recovery [STIR] images) (Fig. 1.6). Proton density-weighted images (PD-WI) are obtained in an intermediate-weighted sequence that is especially useful for cartilaginous assessment (notably when fat suppression is applied – Fig. 1.24), while gradient-echo sequences (also referred to as T2*) are highly sensitive to the presence of calcifications and hemosiderin (Fig.  1.25). Several other sequences are available, and some of them will be discussed in the following chapters. An in-depth analysis of the technical aspects and the complex physics underlying MRI, however, is beyond the scope of this concise introduction. MRI is able to obtain images in any conceivable plane, with excellent spatial and contrast resolutions, and the absence of ionizing radiation in MRI is especially appreciated in the assessment of pediatric patients. The bones and the soft tissues are equally well studied, and the articular cartilage can be clearly distinguished from the epiphyseal cartilage in the growing skeleton in a noninvasive way (Figs. 1.6, 1.9, 1.10, 1.16, 1.18, 1.20,  1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, and 1.31). MRI is superior to US in the assessment of bony structures and better than radiographs, US, and CT in the evaluation of non-osseous structures. Moreover, a unique feature of MRI is the ability to demonstrate the so-­ called bone marrow edema, an abnormal pattern of signal intensity in the cancellous bone characterized by low signal intensity on T1-WI b

image (PD-WI) at the same level (b) demonstrates the irregular contour of the articular cartilage in a noninvasive way and, in addition, shows abnormal intrasubstance signal intensity

1.6 Magnetic Resonance Imaging

19

Fig. 1.24  Fat sat PD-WI of the left knee of a healthy 8-year-old child in the coronal (left) and sagittal (right) planes. MRI is able to assess noninvasively virtually all the osseous and non-osseous structures of the joint, providing excellent anatomic detail

Fig. 1.25  Sagittal T1-WI and gradient-echo image (upper row) and transverse fat sat T2-WI and post-gadolinium fat sat T1-WI (lower row) of the right ankle of an 11-year-old hemophiliac patient. There is joint effusion and synovial impregnation by hemosiderin, which is markedly

hypointense in all sequences (see Chap. 9), related to recurrent hemarthroses. Post-gadolinium image discloses a thickened and enhancing synovium, representing active inflammation and hyperemia

20

1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.25 (continued)

Fig. 1.26  A 9-year-old male with osteochondritis dissecans of the medial femoral condyle. The subchondral bone fragment is clearly seen on a coronal fat sat PD-WI, surrounded by bone marrow edema. Even though there is abnormal signal intensity in the adjacent epiphyseal cartilage, there is no discontinuity of the overlying articular cartilage

and high signal intensity on T2-WI (more evident on fluid-sensitive sequences). Albeit non-specific, this finding is extremely sensitive and serves as a reliable marker of a subjacent abnormality; it is roughly equivalent to the increased uptake found on bone scintigraphy but presents much higher diagnostic accuracy (Figs. 1.18, 1.26, 1.28, and 1.29). MRI uses gadolinium-based compounds as contrast agents, either intravenous or intra-articular (MR-arthrography), tak-

ing advantage of the paramagnetic properties of this chemical element. Intravenous contrast is most useful in the assessment of musculoskeletal infections (Fig.  1.9), tumoral and/or pseudotumoral conditions (Fig.  1.10), and inflammatory and/or hyperemic joint diseases (Figs.  1.25, 1.30, and 1.31) and in the postoperative period. The extent and intensity of post-contrast enhancement parallel the ­inflammatory activity and can be followed in serial studies: the more severe the inflammation, the more intense the enhancement and vice versa. Post-gadolinium enhancement is also an indicator of neoangiogenesis (usually found in hypervascular neoplastic lesions – Fig. 1.10) or of the presence of anomalous vessels (such as those found in vascular malformations). Unlike iodinated contrast agents, gadolinium-­based compounds are not associated to nephrotoxicity. Allergic reactions are extremely uncommon and, when they occur, usually present mild severity. Given that intravenously administered gadolinium compounds are found inside the joint cavities a few minutes after the injection (notably in inflamed joints), post-contrast sequences should be obtained as soon as possible in order to distinguish the thickened synovium from the synovial fluid (Fig. 1.31). For all the explanation above, MRI is the most complete and sophisticated imaging method for the assessment of the immature joint, unrivaled as a tool for early diagnosis. MRI can detect abnormalities related to inflammatory arthropathies – such as juvenile idiopathic arthritis and septic arthritis – still in the preerosive stage, allowing timely introduction of treatment, before the onset of irreversible changes, and, therefore, less severe evolution and better prognosis. Because of its high anatomic

1.6 Magnetic Resonance Imaging

21

Fig. 1.27  MRI of the left knee of a 16-year-old soccer player. Sagittal section of the lower surface. Only MRI can demonstrate such T1-WI (upper row) and fat sat PD-WI (lower row) disclose a non-­ abnormality noninvasively and with this level of detail displaced tear of the posterior horn of the medial meniscus, with tran-

resolution, MRI is also very useful in cancer staging and preoperative planning. Subtle traumatic abnormalities  – which are often “occult” on radiographs – may be heralded by areas of bone marrow edema pattern (Figs. 1.18, 1.28 and 1.29). Recent data have suggested potential usefulness of whole-body MRI (Fig. 1.32) in pediatric rheumatology, mostly in the evaluation of chronic recurrent multifocal osteomyelitis, arthritis, ­dermatomyositis, and connective tissue diseases. Even though

this technique holds promise in several non-oncological settings, including rheumatology, the definition of its role in the investigation of rheumatic diseases is still a work in progress. Nevertheless, like any imaging modality, MRI also has some limitations and drawbacks. MRI is an expensive procedure, whose availability is highly variable worldwide. It is contraindicated for patients with cardiac pacemakers, some types of ferromagnetic intracranial aneurysm clips, and elec-

22

1  Imaging Methods and the Immature Joint: An Introduction

Fig. 1.28  Male adolescent who sustained a traumatic injury to the lumbar region 1 month earlier (fall during a motocross race) presenting persistent low-back pain. Pelvic radiograph (upper left image) failed to disclose any noteworthy abnormalities. However, coronal fat sat T2-WI (upper right image) reveals bone marrow edema along the surfaces of

the left sacroiliac joint, with increased signal intensity within the joint space and in the surrounding soft tissues. Transverse T1-WI and T2-WI (lower row) show widening of the left sacroiliac joint space and irregularity of the corresponding articular surfaces (“occult” posttraumatic diastasis)

tronic monitoring or life-support devices (like infusion pumps or mechanical ventilators), which are incompatible with a strong magnetic field unless otherwise stated. The time for image acquisition is long, the required position may be uncomfortable, a few joints – at the maximum – can be examined in a single session, and the patient has to stand absolutely still; therefore, individuals unable to cooperate will need sedation, increasing the involved costs and risks. Although gadolinium-based contrast agents are not nephrotoxic per se, when administered to patients with moderate to severe renal failure (especially those requiring dialysis), they may lead to a rare, progressive, and potentially fatal disease called nephrogenic systemic fibrosis (NSF), for which no effective treatment exists. Alternative imaging methods should be considered for patients with chronic renal failure if contrast-enhanced MRI is not indispensable; otherwise, informed consent

must be obtained from the patient (or the guardians) and from the requesting physician. In order to minimize the risk of NSF, the lowest possible dose of contrast should be used and dialysis must be performed as soon as possible after MRI. As the incidence of NSF decreased following application of guidelines on restrictive use of gadolinium-­ based contrast agents, increasing the awareness of clinicians and adherence to the guidelines are crucial in order to prevent new cases.

1.7

Dual Energy X-Ray Absorptiometry

Among the several imaging methods able to assess bone mineral density, dual energy X-ray absorptiometry (DEXA) is the most widely used, most studied, and more uniformly standardized. In a nutshell, a DEXA scanner is able to interpret

1.7 Dual Energy X-Ray Absorptiometry

23

Fig. 1.29  Anteroposterior radiograph (left) and coronal fat sat PD-WI (right) of the left knee of a 13-year-old male with a history of joint trauma while playing soccer and persistent pain. The radiograph obtained at initial evaluation is normal, while MRI reveals moderate

1 cm

Contraste esquerda

Fig. 1.30  Tenosynovitis related to juvenile idiopathic arthritis in an adolescent. Transverse post-gadolinium fat sat T1-WI of the left hand discloses synovial enhancement in the flexor tendon sheaths. Even though all digits are affected, enhancement is more intense in the second and in the fifth flexor sheaths. Involution of this enhancement in subsequent studies is an indicator of good response to the treatment; conversely, progression of the findings indicates worsening of the inflammatory process

bone marrow edema in the lateral femoral condyle, as well as an incomplete peripheral fracture of the cancellous bone (arrow). Edema of the soft tissues lateral to the affected femoral condyle is also evident on MRI

the different levels of absorption of X-rays by the different body tissues to estimate the bone mineral density in a given site or in the whole body. The results obtained are quantified in standard deviations and compared with the normal values​​ of a population with similar characteristics (sex, age, and ethnicity), aiming to identify patients with low bone mineral density and increased risk of fractures (Fig. 1.33). Pediatric DEXA is peculiar, differing from that performed in adults as the parameters used are distinct and vary according to the clinical background. The International Society for Clinical Densitometry periodically issues official positions to standardize the procedure, the terms used in the reports, and the uniformity of these reports. These positions are continually updated and are available for reference on the Internet (www. iscd.org).

24

a

1  Imaging Methods and the Immature Joint: An Introduction

b

Fig. 1.31  Coronal fat sat T1-WI of the hips of a 6-year-old female with juvenile idiopathic arthritis. The first image (a), acquired immediately after intravenous administration of contrast, demonstrates joint effusion and synovial thickening in the right hip, with intense enhancement of the inflamed synovium. The joint fluid can be clearly differentiated

from the thickened synovium, mostly adjacent to the acetabular labrum and to the medial cortex of the femoral neck. The second image (b), obtained in the same plane several minutes later, reveals diffusion of the contrast to the joint cavity, making it difficult to distinguish the synovial fluid from the synovium

Fig. 1.32  Whole-body MRI of a young female presenting ovarian cancer and renal cell carcinoma (familial cancer syndrome) performed for detection of metastases, with no signs of distant disease. Whole-body

MRI is unique as it provides global assessment of the organism without exposure to ionizing radiation. (Courtesy of Dr. Vinícius de Araújo Gomes, MD, Tesla Diagnóstico por Imagem, Brasília, Brazil)

1.7 Dual Energy X-Ray Absorptiometry

25

a Name: Patient ID: 174819 DOB: 22 March 1999

Sex: Female Ethnicity: Pediatric

Height: 155.0 cm Weight: 38.0 kg Age: 11

Referring physician: Scan information: Scan date: 22 July 2010 ID: A0722100B Scan type: f Lumbar Spine Analysis: 23 July 2010 08:47 Version 12.7.3.2:5 Lumbar Spine Operator: Model: Comment:

DXA results summary: Region

Image not for diagnostic use k = 1.122, d0 = 52.3 109 x 131

1.4

L1 L2 L3 L4 Total

BMD Area BMC (g) (g/cm2) (cm2) 10.76 7.46 0.693 12.25 8.40 0.685 14.51 10.44 0.719 15.32 10.94 0.714 52.84 37.24 0.705

Tscore

PR (%) 76 67 69 68 70

Zscore 0.5 –0.3 –0.2 –0.2 0.0

AM (%) 109 96 98 97 99

Total BMD CV 1.0%, ACF = 1.042, BCF = 1.010, TH = 4.885

Total

1.2

BMD

1.0 Physician’s comment:

0.8 0.6 0.4 0.2

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Age

T-score vs. pediatric female; Z-score vs. pediatric female. Fig. 1.33  DEXA of the lumbar spine (a) and of the whole body (b) of a healthy 11-year-old female showing that bone mineral density (BMD) is within the normal range when compared to a population with similar characteristics (note the graphs in the lower left corner of the images, in which BMD is plotted, and the charts on the right, where the values

found are stated). On the other hand, the densitometric data (lumbar spine and whole body) of an 8-year-old female with osteogenesis imperfecta (c) reveals marked decrease of the BMD, with consequent increase in the relative risk of fractures

26

1  Imaging Methods and the Immature Joint: An Introduction

b Name: Patient ID: 174819 DOB: 22 March 1999

Sex: Female Ethnicity: Pediatric

Height: 155.0 cm Weight: 39.0 kg Age: 11

Referring physician: Scan information: Scan date: 22 July 2010 ID: A0722100E Scan type: a Whole Body Analysis: 23 July 2010 11:15 Version 12.7.3.2:5 Auto whole body Operator: Model: Comment:

DXA results summary: BMC BMD Area (g) (g/cm2) (cm2) 91.63 0.605 151.34 L Arm 87.80 0.585 R Arm 150.15 35.98 0.500 71.91 L Ribs 29.38 0.480 61.25 R Ribs 69.90 0.565 T Spine 123.68 32.89 0.841 L Spine 39.12 188.87 159.41 0.844 Pelvis 270.67 254.12 0.939 L Leg 252.10 234.43 0.930 R Leg Subtotal 1309.08 995.54 0.760 205.07 332.67 1.622 Head Total 1514.15 1328.21 0.877

Region

Image not for diagnostic use k = 1.187, d0 = 51.5 318 x 150 Total

PR Tscore (%)

79

1.4 Total BMD CV 1.0%, ACF = 1.042, BCF = 1.010 1.2

BMD

1.0 Physician’s comment: 0.8 0.6 0.4

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Age

T-score vs. pediatric female; Z-score vs. pediatric female.

Fig. 1.33 (continued)

Zscore

AM (%)

0.2

101

1.7 Dual Energy X-Ray Absorptiometry

27

c Paciente: Data de Nascimento: 15/6/1999 8,2 anos Altura / Peso: 110,0 cm 16,8 kg Sexo / Etnia: Feminino

ID Estabelecimento: 390030 Médico que Medido: 30/8/2007 Analisado: 8/4/2009

13:32:18 (9,15) 17:16:05 (9,30)

Jovem Adulto Corr. Etária Referencia: Coluna AP L1-L4 BMD T-Score BMD (g/cm2) (g/cm2) Região z-Score 1,43 –2,8 0,394 L1 1,30 –3,3 0,418 L2 1,18 –2,9 0,451 L3 1,06 –3,4 0,403 L4 0,93 –3,1 0,417` L1-L4 0,81 0,68 0,56 0,44 0,31 5 10 15 20 Correspondência com Idade Idade (anos) NHANES/EUA Coluna AP População de Referência (v104) Estatisticamente 68% de exames repetidos situam-se dentro de 1DP (± 0,010 g/cm2 para Coluna AP L1-L4) Imagem não destinada a diagnóstico Referência: Corpo Inteiro Total BMD (g/cm2) 1,25 1,19 1,13 1,06 1,00 0,94 0,87 0,81 Idade: 8,2 0,75 0,68 20 5 Idade do esqueleto: 7,8 Idade (anos) Imagem não destinada a diagnóstico

Região Braços Pernas Tronco Costelas Pelve Coluna Total Total (Cabeça)

BMD (g/cm2) 0,487 0,581 0,514 0,497 0,497 0,554 0,697 0,536

Jovem Adulto T-Score -

Corr. Etária z-Score –2,2 –2,5

Correspondência com Idade, Etnla NHANES/EUA Corpo Inteiro População de Referência (v104) Estatisticamente 68% de exames repetidos situam-se dentro de 1DP (± 0,010 g/cm2 para Corpo Inteiro Total)

Fig. 1.33 (continued)

Key Points • Radiographs are inexpensive, largely available, and useful in the follow-up of already established bone abnormalities. Nonetheless, they are limited for early diagnosis of joint diseases and for the assessment of the soft tissues. As a general rule, radiographs should always be available before requesting more sophisticated imaging studies. • US is inexpensive, well-tolerated, and sensitive to synovitis and hyperemia, yielding images in real time. However, it is an operator-dependent study, limited to the assessment of superficial structures. Despite its usefulness for the evaluation of the soft tissues, little information (or no information at all) can be obtained about the bones.

• Bone scintigraphy is a highly sensitive imaging method that is able to study the entire skeleton in a single study and detect “occult” sites of multifocal disease (tumors, infection, arthritis). Nonetheless, low specificity, exposure to radiation, and poor spatial resolution limit its usefulness in children. • CT has high spatial resolution and multiplanar capabilities, providing excellent assessment of bone anatomy. However, it delivers ionizing radiation and is limited in the evaluation of the soft tissues, and the iodinated contrast agents are potentially nephrotoxic. CT is more useful in the evaluation of osteoarticular trauma or as a diagnostic alternative if MRI is not available.

28

1  Imaging Methods and the Immature Joint: An Introduction

• MRI is inherently multiplanar, nonionizing, and highly sensitive, with high spatial and contrast resolutions. It is very useful for early diagnosis of osteoarticular conditions and to monitor the evolution of inflammatory joint diseases. Nevertheless, it is an expensive procedure whose availability is variable worldwide, and there are some absolute contraindications. Furthermore, pediatric patients often need sedation, increasing the involved costs and risks. • DEXA is the method of choice to assess bone mineral density, detecting individuals with increased risk of fractures. However, it is not useful in the assessment of the joints.

Recommended Reading 1. Alizai H, Chang G, Regatte RR. MRI of the musculoskeletal system: advanced applications using high and ultrahigh field MRI. Semin Musculoskelet Radiol. 2015;19:363–74. 2. Allen G, Wilson D, Graham R, Jacob D. Échographie pédiatrique ostéo-articulaire. J Radiol. 2005;86:1924–30. 3. Babyn P, Doria AS. Radiologic investigation of rheumatic diseases. Rheum Dis Clin N Am. 2007;33:403–40. 4. Boavida P, Muller LS, Rosendahl K. Magnetic resonance imaging of the immature skeleton. Acta Radiol. 2013;54:1007–14. 5. Buchmann RF, Jaramillo D. Imaging of articular disorders in children. Radiol Clin N Am. 2004;42:151–68. 6. Daftari Besheli L, Aran S, Shaqdan K, Kay J, Abujudeh H. Current status of nephrogenic systemic fibrosis. Clin Radiol. 2014;69:661–8. 7. Daldrup-Link HE, Steinbach L. MR imaging of pediatric arthritis. Magn Reson Imaging Clin N Am. 2009;17:451–67. 8. Damasio MB, Magnaguagno F, Stagnaro G.  Whole-body MRI: non-oncological applications in paediatrics. Radiol Med. 2016;121:454–61. 9. Damilakis J, Maris TG, Karantanas AH. An update on the assessment of osteoporosis using radiologic techniques. Eur Radiol. 2007;17:1591–602. 10. Delle Sedie A, Riente L, Bombardieri S. Limits and perspectives of ultrasound in the diagnosis and management of rheumatic diseases. Mod Rheumatol. 2008;18:125–31. 11. DiPietro MA, Leschied JR.  Pediatric musculoskeletal ultrasound. Pediatr Radiol. 2017;47:1144–54. 12. Fritzsche PJ.  Communication: the key to improved patient care. Radiology. 2005;234:13–4.

13. Hryhorczuk AL, Restrepo R, Lee EY.  Pediatric musculoskeletal ultrasound: practical imaging approach. AJR Am J Roentgenol. 2016;206:W62–72. 14. Hustinx R, Malaise MG.  PET imaging of arthritis. PET Clin. 2006;1:131–9. 15. Imhof H, Mang T.  Advances in musculoskeletal radiology: multidetector computed tomography. Orthop Clin North Am. 2006;37:287–98. 16. Jaramillo D, Laor T.  Pediatric musculoskeletal MRI: basic principles to optimize success. Pediatr Radiol. 2008;38:379–91. 17. Johnson K. Imaging of juvenile idiopathic arthritis. Pediatr Radiol. 2006;36:743–58. 18. Kalkwarf HJ, Abrams SA, DiMeglio LA, Koo WW, Specker BL, Weiler H, et al. Bone densitometry in infants and young children: the 2013 ISCD Pediatric Official Positions. J Clin Densitom. 2014;17:243–57. 19. Malattia C, Tzaribachev N, van den Berg JM, Magni-Manzoni S. Juvenile idiopathic arthritis – the role of imaging from a rheumatologist's perspective. Pediatr Radiol. 2018;48:785–91. 20. Matuszewska G, Zaniewicz-Kaniewska K, Włodkowska-­ Korytkowska M, Smorawińska P, Saied F, Kunisz W, et  al. Radiological imaging in pediatric rheumatic diseases. Pol J Radiol. 2014;79:51–8. 21. Maurer K. Musculoskeletal ultrasound in childhood. Eur J Radiol. 2014;83:1529–37. 22. Miller E, Uleryk E, Doria AS. Evidence-based outcomes of studies addressing diagnostic accuracy of MRI of juvenile idiopathic arthritis. AJR Am J Roentgenol. 2009;192:1209–18. 23. Nadel HR, Stilwell ME.  Nuclear medicine topics in pediatric musculoskeletal disease: techniques and applications. Radiol Clin North Am. 2001;39:619–51. 24. Parisi MT, Iyer RS, Stanescu AL. Nuclear medicine applications in pediatric musculoskeletal diseases: the added value of hybrid imaging. Semin Musculoskelet Radiol. 2018;22:25–45. 25. Patel AS, Soares B, Courtier J, Mackenzie JD.  Radiation dose reduction in pediatric CT-guided musculoskeletal procedures. Pediatr Radiol. 2013;43:1303–8. 26. Piccolo CL, Galluzzo M, Ianniello S, Trinci M, Russo A, Rossi E, et al. Pediatric musculoskeletal injuries: role of ultrasound and magnetic resonance imaging. Musculoskelet Surg. 2017;101:85–102. 27. Rodriguez-Lozano AL, Giancane G, Pignataro R, Viola S, Valle M, Gregorio S, et al. Agreement among musculoskeletal pediatric specialists in the assessment of radiographic joint damage in juvenile idiopathic arthritis. Arthritis Care Res (Hoboken). 2014;66:34–9. 28. Sheybani EF, Khanna G, White AJ, Demertzis JL. Imaging of juvenile idiopathic arthritis: a multimodality approach. Radiographics. 2013;33:1253–73. 29. Windschall D.  Möglichkeiten der Bildgebung in der Kinder- und Jugendrheumatologie. Z Rheumatol. 2016;75:973–86. 30. Yamashita H, Kubota K, Mimori A. Clinical value of whole-body PET/CT in patients with active rheumatic diseases. Arthritis Res Ther. 2014;16:423.

2

Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

2.1

Introduction

There is a proverbial saying in medicine that “children are not small adults.” This is especially true in pediatric imaging, given that the “normal” appearance changes in time with the structural and physiologic changes of normal growth. The adult skeleton, for example, is very different from that of the skeletally immature individual, and there are notable differences between the bones of a newborn and those of a toddler. Many radiologists – even experienced professionals – do not feel comfortable with pediatric studies, including those related to the immature musculoskeletal system. The most important cause of this aversion is, by far, lack of familiarity with the normal appearance of the growing skeleton and its developmental peculiarities; this unawareness is a barrier both to recognition of normal patterns and to the diagnosis of pathological findings. The purpose of this chapter is to provide the reader with a brief review of the anatomical, histological, and physiological bases of osteoarticular development, which are crucial for interpretation and understanding of pediatric musculoskeletal imaging.

2.2

 he Immature Epiphysis T and the Physis

A unique feature of the immature skeleton is the presence of cartilaginous structures in the extremities of the long bones, namely, the epiphyseal cartilage and the physis (also referred to as primary physis, growth cartilage, or growth plate), which involute with skeletal maturation and are no longer present in the adult organism. These cartilages act together as a functional unit responsible for the longitudinal growth of the bone. On the other hand, the articular cartilage protects and nourishes the subchondral bone of the joint surfaces and, unlike the physis and the epiphyseal cartilage, does not involute, remaining throughout the life course. Radiographs are totally insensitive to demonstrate these cartilages (Fig.  2.1), and computed

Fig. 2.1  Radiograph of the right wrist of a healthy 8-year-old male showing that ossification has already begun in the carpal bones and in the distal radial epiphysis. However, as radiographs are fairly insensitive for cartilaginous assessment, only an indirect estimate of the thickness of the physes, of the cartilaginous anlage of the carpal bones, and of the epiphyseal cartilages can be made. The distal epiphysis of the ulna is entirely cartilaginous and completely invisible

tomography (CT) and ultrasonography (US) are also limited in their evaluation. Because of its characteristics (see Chap. 1), magnetic resonance imaging (MRI) is the preferred imaging method for assessment of most structures of the immature bone (Fig. 2.2).

© Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_2

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2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

Fig. 2.2  MRI of the right wrist of a young male whose age is similar to that of the child of Fig. 2.1. Coronal T1-WI (left), fat sat PD-WI (center), and gradient-echo image (right) show that the ossified portions of the carpal bones are isointense with the medullary bone seen in the metacarpals, the distal metaphyses of the radius and ulna, and the ossified portion of the distal epiphysis of the radius. Even though the distal

epiphysis of the ulna is entirely cartilaginous, the epiphyseal cartilage is clearly seen, presenting low to intermediate signal intensity on T1-WI and intermediate to high signal intensity in the other sequences; a similar behavior is seen in the cartilaginous anlage of the carpal bones and in the cartilaginous portion of the distal epiphysis of the radius

The immature epiphysis is situated between the joint cavity and the physis. During the early stages of development, the epiphyses are entirely cartilaginous, serving as precursors for the ossified ends of the long bones. The cartilaginous epiphysis usually displays intermediate signal intensity on T1-WI and fluid-sensitive sequences, being hypointense relative to the physis and the articular cartilage on the latter. Transformation of cartilage into bone begins in the inner portion of the epiphysis, the so-called secondary ossification center (given that primary ossification centers form the diaphyses of the tubular bones during intrauterine life). Ossification may occur in a single center (like in the proximal or distal femoral epiphyses – Fig. 2.3) or, less often, via multiple secondary ossification centers that later coalesce (as in the distal humerus  – Fig. 2.4). The secondary ossification center is surrounded by a specialized structure, the secondary physis, responsible for the endochondral ossification and structurally similar to the primary physis, appearing as a thin layer of high signal intensity on fluid-sensitive sequences (Figs. 2.5 and 2.6). Foci of high signal intensity on fluid-­sensitive sequences and intermediate to high signal on gradient-­ echo images in the epiphyseal cartilage corresponding to

pre-ossification phenomena are seen before the appearance of the secondary ossification center (Fig. 2.4). Once ossified, the center is oval and/or round, evolving to a hemispheric configuration over time; it increases in size and molds to the contour of the epiphysis in which is settled, at the same time as there is thinning of the epiphyseal cartilage (Figs.  2.7 and 2.8). The epiphyseal cartilage is homogeneous throughout the first year of life, but, as skeleton maturation takes place, focal areas of high signal intensity on fluid-sensitive sequences appear (Figs.  2.3, 2.6, and 2.8), classically in the posterior aspect of the femoral condyles. Such areas are more common in preadolescent males and are typically not associated with abnormalities of the subchondral bone, being deprived of significance and representing the earliest stages of endochondral ossification. Focal and heterogeneous at first, they become more extensive and uniform with time (Fig.  2.8). As the child begins to walk, the weight-bearing portions of the epiphyseal cartilages present a decrease in their signal intensity on T2-WI, more evident in the knees and the hips, also deprived of importance (Figs. 2.6 and 2.8). Irregularity or spiculation of the secondary ossification centers at the bone and/or cartilage junction is a normal finding, mostly seen during

2.2 The Immature Epiphysis and the Physis

a

31

b

c

Fig. 2.3  Coronal T1-WI (a) and fat sat T2-WI (b) of the left hip of a 3-year-old male. The secondary ossification center of the femoral head is already present, whose bone marrow has undergone complete conversion to the fatty type. On the other hand, the bone marrow of the femoral metaphysis and of the iliac bone presents predominance of the hematopoietic variety. The epiphyseal cartilage is predominantly isointense on

T1-WI and shows intermediate signal intensity on fat sat T2-WI. There is a small focus of increased signal intensity on T2-WI in the apex of the epiphyseal cartilage, related to pre-ossification changes. The difference between the signal intensity of the yellow marrow (epiphyseal) and the red marrow (metaphyseal and diaphyseal) is even more conspicuous in sagittal images of the knee of a school-aged child (c)

32 Fig. 2.4  In (a), coronal T1-WI (left) and fat sat T2-WI (right) of the left elbow of a 6-year-old female show that the ossification center of the capitulum is already filled with yellow marrow. The trochlear portion of the distal epiphysis of the humerus is completely cartilaginous, and increased signal intensity is seen in this cartilage on fat sat T2-WI, representing pre-ossification phenomena. In (b), volume-­ rendered CT reconstructions of the left elbow of a 13-year-old male demonstrate that all the ossification centers are ossified, with partial fusion of the ossification center of the capitulum. Despite the excellent anatomic detail of bone provided by CT, very limited information can be obtained with this imaging method about the cartilaginous structures

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

a

b

2.2 The Immature Epiphysis and the Physis Fig. 2.5  Sagittal T1-WI (left) and fat sat T2-WI (right) of the right knee of a 13-year-old male. The secondary physis and the articular cartilage of the distal femur are clearly identified on fat sat T2-WI as linear areas of high signal intensity situated between the ossified and the cartilaginous portion of the epiphysis and along the joint surface of the epiphyseal cartilage, respectively. Bone marrow conversion is already complete in the epiphyses, while there is residual red marrow in the metaphyses, with its typical flame-shaped appearance

Fig. 2.6  Sagittal fat sat T2-WI of the left hip of a toddler. Although the epiphyseal cartilage displays predominantly intermediate signal intensity, there is low signal intensity in the weight-bearing zone, located in the uppermost portion of the epiphysis. In addition, foci of increased signal intensity are also found in the apex of the epiphyseal cartilage, related to ongoing ossification. The secondary physis appears as a thin hyperintense line surrounding the secondary ossification center, between the latter and the epiphyseal cartilage. The physis and the articular cartilage are also hyperintense if compared to the epiphyseal cartilage

33

34

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

a

b

Fig. 2.7  Sagittal PD-WI of the medial femoral condyles of two different children – the first is a 7-year-old subject (a) and the second one is a 13-year-old individual (b) – displaying the epiphyseal cartilage (*) as a structure of intermediate signal intensity between the hyperintense

articular cartilage and the hypointense secondary ossification center. The ossification center is smaller, and the cartilage is proportionally thicker in younger children

Fig. 2.8  Sagittal fat sat T2-WI of the knees of two distinct boys, a 5-year-old (left) and a 7-year-old (right). There is rapid epiphyseal growth over time, with increase in the size of the secondary ossification center and reduction of the thickness of the epiphyseal cartilage. In the first image, marked hyperintensity is present in the primary spongiosa of the distal femur; a zone of increased signal intensity within the posterior portion of the epiphyseal cartilage of the femoral condyle repre-

sents ongoing ossification. The second image also shows hyperintensity of the posterior portion of the epiphyseal cartilage, more diffuse if compared to that seen in the first child. The focal area of decreased signal intensity seen in the weight-bearing zone of the epiphyseal cartilage of the femur in the second image is deprived of significance, typical of ambulating children

2.2 The Immature Epiphysis and the Physis

Fig. 2.9  Lateral view of the right knee of a 9-year-old female. The irregular contour of the posterior aspect of the femoral condyles is a normal finding, related to skeletal maturation Fig. 2.10  Radiographs (a) and reformatted CT images (b) of the right knee of a 2-year-old female. Normal spiculation of the contour of the ossified portions of the femoral condyles can be seen, mostly medial, related to activity in the bone and/or cartilage interface

a

35

growth spurts (Figs.  2.9 and 2.10). Accessory ­ossification centers may also be present, usually adjoining the posterior aspect of the secondary ossification centers of the distal femur, not associated with bone marrow edema or abnormalities of the overlying cartilage and eventually becoming fused with the secondary center itself. Furthermore, carpal and tarsal bones of healthy children may show focal areas of cortical depression, which may be multiple and occasionally simulate bone erosions: preservation of articular cartilage, absence of bone marrow edema, and normal post-contrast enhancement help to rule out erosive disease. Vascular supply is abundant in the epiphyseal cartilage, more evident on post-gadolinium T1-WI, appearing as dotted or linear areas of enhancement (Fig. 2.11). The articular cartilage is hardly discernible on T1-WI, appearing as a thin layer of high signal intensity surrounding the immature epiphysis on T2-WI (Figs. 2.5, 2.6, 2.7, 2.8 and 2.12), which becomes more conspicuous as the maturation process comes to an end (Fig. 2.13). The physis is a specialized area of the bone, situated between the epiphysis and the metaphysis. It is divided into several zones, each one of them with distinct histological appearances and functions in the process of endochondral ossification. The germinal layer (resting zone) abuts the epiphysis and is composed mainly by abundant matrix and loosely organized chondrocytes, providing the cells responsible for growth; lesions of this layer (such as those found in  transphyseal fractures, for instance) may lead to arrested bone growth. The proliferating zone is constituted

36 Fig. 2.10  (continued)

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

b

Fig. 2.11  Axial fat sat post-gadolinium T1-WI at the level of the proximal tibial epiphysis showing the normal vascular supply of the epiphyseal cartilage of a 3-year-old female as a web of punctate and linear

areas of enhancement; the ossified nucleus of the epiphysis is seen in its central portion in the second image as an oval area of low signal intensity

2.2 The Immature Epiphysis and the Physis

37

Fig. 2.12  Coronal gradient-­ echo images of the left knee of a 5-year-old child. The epiphyseal cartilages of the distal femur and of the proximal tibia are clearly distinguished from the adjacent articular cartilages: the latter are noticeably brighter, with signal intensity similar to that of the physeal cartilage. The smooth and regular physes are typical of younger children. As the menisci are composed of fibrocartilage, they appear as triangular structures with uniform low signal intensity

Fig. 2.13  Coronal fat sat PD-WI of the left knee of a 15-year-old female displaying in detail the normal articular cartilages of the femoral condyles and of the tibial plateaus (asterisks)

by flattened chondrocytes with intense mitotic activity, which are arranged in columns and separated by bars of chondroid matrix. These columns of cells present continuous migration to the metaphysis, fed by cellular division in their basal portions. Conversely, there is no active cellular division in the hypertrophic cell zone, where the chondrocytes reach their maximum size and undergo vacuolation. Finally, after

the death of the chondrocytes and upon production of alkaline phosphatase in the provisional calcification zone, the metaphyseal vessels invade the extracellular matrix, which becomes mineralized and serve as a scaffold for the osteogenesis. These vessels bring osteoprogenitor cells, which differentiate into osteoblasts and form bone in the spaces left behind by the chondrocytes. The thickness of the physis is relatively uniform during growth due to a strict balance between production of cartilage and removal of chondrocytes. The physes of young children are flat, becoming wavy as the growth advances (Figs. 2.12, 2.14, and 2.15). The primary spongiosa is the portion of the metaphysis adjacent to the physis, composed of newly formed bone, which appears hyperintense on fluid-sensitive sequences (Figs. 2.8, 2.14, 2.16, and 2.17). Even though the several physeal zones cannot be discriminated as distinct regions on MRI, the normal physis has a three-layered appearance: in addition to the primary spongiosa, it is possible to distinguish the provisional calcification zone, which is hypointense in all sequences because of its mineralized  matrix, and the physeal cartilage itself, which displays intermediate signal on T1-WI and intermediate and/or high signal intensity on fluid-sensitive sequences

38

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

Fig. 2.14  Sagittal fat sat T2-WI of the right ankle of an 8-year-old female. The distal physis of the tibia presents the classic three-layered appearance, with high signal intensity in the physeal cartilage and in the primary spongiosa and an intervening line of low signal intensity corresponding to the provisional calcification zone. The physis is almost flat, a normal finding for the patient’s age. Foci of increased signal intensity are seen in the medullary bone of the hindfoot and midfoot, deprived of significance

Fig. 2.15  Sagittal fat sat T2-WI of the right ankle of a 12-year-old female. If compared to the child of Fig. 2.14, the distal tibial physis is wavier and presents reduced thickness, findings related to progression of bone maturation. The calcaneal apophysis is already incorporated to the body of the bone

Fig. 2.16  Sagittal fat sat T2-WI of the left knee of a 10-year-old male. There is physiological hyperintensity in the primary spongiosa of the distal femur and proximal tibia, which should not be confused with bone marrow edema

(Figs.  2.14 and 2.17). Once bone maturation is complete, there is progressive narrowing of the physis, which usually starts centrally and proceeds peripherally until its eventual disappearance (Figs. 2.15 and 2.18). The physeal scar is a thin sclerotic line located where once was the physis, which is more evident in the first years after physeal closure and tends to fade over time, remaining throughout life as a linear area of low signal intensity in all sequences on MRI (Fig. 2.19). Areas of bone marrow edema centered about the closing physis are occasionally found in adolescents, notably in the knees. Such areas of focal periphyseal edema typically affect the epiphyseal and the metaphyseal bone marrow and may be occasionally painful, probably representing the early stages of active physeal closure (Fig. 2.20); in the authors’ experience, post-contrast enhancement may also be present (Fig. 2.21). They can be found in more than one bone in the same joint or even in more than one joint at the same time, usually resolving with conservative treatment, with no need for imaging follow-up. Transphyseal vessels involute around 18 months of extrauterine life, so that epiphyseal and metaphyseal vascular beds become separated; thus, from this age until skeletal maturation,

2.2 The Immature Epiphysis and the Physis Fig. 2.17  Coronal fat sat T2-WI of the right knee of a 13-year-old male. The physes display their characteristic three-layered appearance, which is more evident in the proximal tibia. Intermediate to high signal intensity can be seen in the flame-shaped red marrow of the metaphyses, notably in the distal femur

Fig. 2.18  In (a), radiograph of the fingers of a 14-year-old male shows that the central physes of the distal phalanges are already closed and that only peripheral areas are yet to fuse. Reformatted coronal (left) and sagittal (right) CT images of the right ankle of a 13-year-old female (b) reveal a Salter-Harris type III avulsion fracture of the anterolateral portion of the distal tibial epiphysis (Tillaux fracture); note that the central, medial, and posterior portions of the physis are already closed. Closure of the distal tibial growth plate starts centrally and medially, progresses to posteriorly and laterally, and finishes at the anterolateral portion, rendering the epiphysis adjacent to the latter prone to avulsion injuries during the final stages of the process. The juvenile Tillaux fracture is a practical example of how the centrifugal pattern of closure of the growth plates may be of clinical importance

a

b

39

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2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

Fig. 2.19  In (a), anteroposterior and lateral views of the right ankle of a 20-year-old female display the physeal scar of the distal tibia as a thin dense line interposed between the metaphysis and the epiphysis below. In (b), sagittal T1-WI of the lateral femoral condyles and tibial plateaus of two distinct girls (a 15-year-­ old [left] and a 25-year-old [right]) show the physeal scars as faint lines of low signal intensity; the red marrow – which displays intermediate signal intensity and is far more abundant in the younger individual – is confined to the metaphyseal regions and abuts the scars, sparing the epiphyses

a

b

open physes usually act as physiological barriers limiting the propagation of neoplastic lesions and infections (Fig. 2.22).

2.3

Pediatric Bone Marrow

The bone marrow is the main hematopoietic organ. As a consequence of its variable and dynamic composition, its appearance on imaging changes considerably during skeletal maturation. For instance, in newborns the bone marrow is entirely of the hematopoietic type (red marrow), which presents low signal intensity on T1-WI (similar to or higher than that of the skeletal muscle) and intermediate to high signal intensity on fluid-sen-

sitive sequences. The conversion of red marrow to yellow (fatty) marrow in the appendicular skeleton begins in the first year of life and happens expeditiously, following a stereotyped pattern, being almost complete by the time of skeletal maturity. As the yellow marrow is composed mostly by fat, conversion leads to increase in the signal intensity of the bone marrow on T1-WI and signal drop in sequences with fat suppression, a pattern similar to that of the subcutaneous tissue. The conversion process starts in the distal portions of the limbs (phalanges of the hands and feet) and advances centripetally to the proximal bones (humeri and femora), extending proximally to the axial skeleton. However, if the long bones are considered individually, the pattern of marrow replacement is centrifugal, beginning in the mid-diaphysis and advancing toward

2.3 Pediatric Bone Marrow

41

a

b

Fig. 2.20  A 14-year-old female complaining of pain in both knees. Coronal fat sat PD-WI (a) and sagittal T1-WI (b, left images) and fat sat PD-WI (b, right images) of the right knee reveal focal areas of bone

marrow edema pattern centered about the physes of the distal femur and proximal tibia. Similar findings can be seen in the contralateral femur (c and d)

42

c

d

Fig. 2.20  (continued)

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

2.3 Pediatric Bone Marrow Fig. 2.21  A 13-year-old female complaining of right knee pain. Coronal T1-WI (upper left image) and fat sat T2-WI (upper right image) disclose bone marrow edema centered about the distal femoral physis, with questionable physeal narrowing. Post-gadolinium fat sat T1-WI (lower left image) discloses enhancement of the edematous bone marrow, while coronal reformatted CT image of the same knee (lower right image) shows sclerosis of the cancellous bone in the affected area and unequivocal focal narrowing of the growth plate. Focal periphyseal edema

43

44

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

Fig. 2.22  An 11-year-old male with aggressive sarcoma of the right proximal tibia. In addition to an anteroposterior view of the proximal leg (upper left image), transverse fat sat T2-WI (upper right image), coronal fat sat T2-WI (lower left image), and post-gadolinium fat sat T1-WI (lower right image) are also shown. The radiograph reveals heterogeneous bone sclerosis, spiculated periosteal reaction, and an adja-

cent soft-tissue mass. On MRI, the bone marrow of the proximal metadiaphysis of the tibia is diffusely infiltrated by the tumor, with an extensive subperiosteal component. Nonetheless, the proximal tibial epiphysis presents normal signal intensity, as the progression of the sarcoma was halted by the open physis

2.3 Pediatric Bone Marrow

Fig. 2.23  Coronal T1-WI of the legs of a 10-year-old male demonstrating the normal centrifugal pattern of bone marrow conversion, with preponderance of the hyperintense yellow marrow in the tibial diaphyses and residual red marrow predominantly located in the metaphyses, mainly the proximal ones Fig. 2.24  Coronal T1-WI (left) and fat sat T2-WI (right) of the left hip of a 35-year-old female. There is residual red marrow intertwined with yellow marrow, the former predominantly found in the proximal femoral metadiaphysis and in the iliac bone. Red marrow is no longer present in the femoral epiphysis and in the greater trochanter, which are completely occupied by yellow marrow

45

the metaphyses (Fig. 2.23). In the epiphyses, although the bone marrow of the newly formed secondary ossification centers is ­essentially of the hematopoietic type, complete conversion occurs within 6  months of their radiographic appearance (Figs.  2.2, 2.3, 2.4, and 2.5). Regarding the spine, the ossified portion of the vertebrae is usually hypointense on T1-WI if compared to the skeletal muscle during the first month of life, with progressive increase of signal intensity from the first to the sixth month and becoming hyperintense from then on. On fluid-­sensitive sequences, the signal intensity of the vertebrae presents progressive reduction if compared to the skeletal muscle, going from isointense and/or slightly hyperintense in young children to hypointense in older individuals. Marrow conversion is progressive and continuous in the axial skeleton, also occurring throughout adult life. In the pelvic bones, marrow conversion is usually more heterogeneous, intertwining areas of red marrow and yellow marrow (Fig. 2.24).

46

2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

It is important to keep in mind some normal and peculiar aspects of the pediatric bone marrow that may be mistakenly construed as abnormal. Residual red marrow adjacent to the metaphysis, for instance, has a typical “flame-shaped” appearance, based on the physis and showing imprecise borders; it blends gradually with the adjacent yellow marrow, without trabecular distortion or associated mass effect Fig. 2.25  Coronal T1-WI (left) and fat sat T2-WI (right) of the left hip of an 8-year-old male. A thick cartilaginous anlage is still present in greater trochanter apophysis, while ossification of the femoral head is far more advanced. The secondary ossification center of the femoral epiphysis shows complete conversion to yellow marrow, while red marrow is still predominant in the metaphysis

Fig. 2.26  Coronal T1-WI (left) and sagittal fat sat T2-WI (right) of the right shoulder of a 10-year-old male. The secondary ossification center of the proximal epiphysis of the humerus presents complete bone marrow conversion, and its signal intensity is identical to that of the subcutaneous fat in all sequences. Marrow conversion of the diaphyseal and metaphyseal regions is still happening, with predominance of red marrow in juxtaphyseal areas, characterized by intermediate signal intensity on T1-WI and high signal intensity on fat sat T2-WI

(Figs.  2.5, 2.17, 2.23, and 2.25). The vast majority of ­pathologic marrow lesions will display very low signal intensity on T1-WI and marked hyperintensity in fluidsensitive sequences (Fig. 2.22). T1 is the most important sequence for this kind of assessment, as fluid-sensitive sequences frequently overestimate the signal intensity of the red marrow (Figs. 2.25, 2.26, and 2.27). Residual red

2.3 Pediatric Bone Marrow

Fig. 2.27  Sagittal T1-WI of the left knee of a 13-year-old male demonstrating the appropriateness of T1-weighted sequences for the assessment of bone marrow. While the epiphyseal yellow marrow presents high signal intensity, similar to that of the subcutaneous fat, metaphyseal red marrow presents low signal intensity. However, red marrow is hyperintense if compared to the skeletal muscle, excluding the possibility of marrow infiltration

Fig. 2.28  Sagittal fat sat proton density-weighted images of the left knee of an 8-year-old female complaining of heel pain. Scattered foci of increased signal intensity can be seen in the medullary bone of talus and in the midfoot, which are commonly found in healthy children and may represent residual red marrow or mechanical stress related to normal activity. The calcaneus (not shown) was normal

47

marrow is ­commonly found in the proximal metaphysis of the long bones of young adults and should not be misinterpreted as marrow infiltration (Fig. 2.24). Additionally, a significant percentage of asymptomatic children present focal areas of increased signal intensity on fluid-sensitive sequences in their ankles and feet and in the carpal bones, usually bilateral and symmetric, which may be due to mechanical stress related to normal activity or represent residual perivascular islets of red marrow (Figs.  2.14 and 2.28); this finding is deprived of any clinical meaning and tend to disappear in time. Residual red marrow may also be present in the epiphyses, presenting either as a peripheral halo – mirroring the centrifugal pattern of conversion – or as islets permeating the fatty marrow. Post-gadolinium enhancement is found in the normal bone marrow, mainly in the red marrow of young children, in the primary spongiosa and in the physis (physeal enhancement is more prominent than that of the epiphyseal cartilage – Fig. 2.29).

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2  Imaging of Peculiar Aspects of the Anatomy and Development of the Growing Skeleton

Fig. 2.29  Coronal images (fat sat T1-WI) of the left hip of a 13-year-old male before (left) and after (right) intravenous administration of gadolinium. Enhancement of the red marrow (mostly diaphyseal) is more intense than that of the yellow marrow (mainly epiphyseal and metaphyseal). Physeal enhancement is more intense than that seen in the epiphyseal cartilage

Key Points

• The epiphyseal cartilage and the physis act together as a functional unit, responsible for longitudinal growth of the bone. The appearance of these structures changes along the course of skeletal development, and awareness of these normal changes helps to avoid erroneous interpretation. • The epiphysis is entirely cartilaginous in newborns, undergoing progressive ossification that begins in its innermost portion, the secondary ossification center. Changes in the signal intensity of the epiphyseal cartilage related to pre-ossification phenomena should not to be confused with cartilaginous injuries. • The physis has a typical three-layered appearance on fluid-sensitive sequences, constituted by the hyperintense physeal cartilage, the hypointense provisional calcification zone, and the hyperintense primary spongiosa. In adolescents, areas of focal periphyseal edema can be found and are probably related to active closure of the growth plates. • The appearance of the normal bone marrow changes significantly with growth. In newborns, the marrow is entirely of the hematopoietic type (red), presenting progressive conversion to fatty (yellow) marrow as the skeletal maturation advances. Residual areas of red marrow intertwined with yellow marrow are a major pitfall in MRI interpretation.

Recommended Reading 1. Baheti AD, Iyer RS, Parisi MT, Ferguson MR, Weinberger E, Stanescu AL. “Children are not small adults”: avoiding common pitfalls of normal developmental variants in pediatric imaging. Clin Imaging. 2016;40:1182–90. 2. Barnewolt CE, Shapiro F, Jaramillo D.  Normal gadolinium-­ enhanced MR images of the developing appendicular skeleton: part 1. Cartilaginous epiphysis and physis. AJR Am J Roentgenol. 1997;169:183–9. 3. Beckmann N, Spence S.  Unusual presentations of focal periphyseal edema zones: a report of bilateral symmetric presentation and partial physeal closure. Case Rep Radiol. 2015. https://doi. org/10.1155/2015/465018. 4. Boavida P, Muller LS, Rosendahl K. Magnetic resonance imaging of the immature skeleton. Acta Radiol. 2013;54:1007–14. 5. Brian JM, Choi DH, Moore MM.  The primary physis. Semin Musculoskelet Radiol. 2018;22:95–103. 6. Burdiles A, Babyn PS. Pediatric bone marrow MR imaging. Magn Reson Imaging Clin N Am. 2009;17:391–409. 7. Cairns R. Magnetic resonance imaging of the growth plate: pictorial essay. Can Assoc Radiol J. 2003;54:234–42. 8. Chauvin NA, Jaimes C, Laor T, Jaramillo D. Magnetic resonance imaging of the pediatric shoulder. Magn Reson Imaging Clin N Am. 2012;20:327–47. 9. Ecklund K, Jaramillo D. Imaging of growth disturbance in children. Radiol Clin N Am. 2001;39:823–41. 10. Gilbert C, Babyn P. MR imaging of the neonatal musculoskeletal system. Magn Reson Imaging Clin N Am. 2011;19:841–58. 11. Gill KG, Nemeth BA, Davis KW.  Magnetic resonance imag ing of the pediatric knee. Magn Reson Imaging Clin N Am. 2014;22:743–63. 12. Jaimes C, Chauvin NA, Delgado J, Jaramillo D.  MR imaging of normal epiphyseal development and common epiphyseal disorders. Radiographics. 2014;34:449–71.

Recommended Reading 13. Jaimes C, Jimenez M, Marin D, Ho-Fung V, Jaramillo D.  The trochlear pre-ossification center: a normal developmental stage and potential pitfall on MR images. Pediatr Radiol. 2012;42:1364–71. 14. Jans LB, Jaremko JL, Ditchfield M, Verstraete KL.  Evolution of femoral condylar ossification at MR imaging: frequency and patient age distribution. Radiology. 2011;258:880–8. 15. Jaramillo D.  Cartilage imaging. Pediatr Radiol. 2008;38(Suppl 2):S256–8. 16. Jaramillo D, Hoffer FA. Cartilaginous epiphysis and growth plate: normal and abnormal MR imaging findings. AJR Am J Roentgenol. 1992;158:1105–10. 17. Kan JH.  Major pitfalls in musculoskeletal imaging-MRI.  Pediatr Radiol. 2008;38(Suppl 2):S251–5. 18. Kellenberger CJ.  Pitfalls in paediatric musculoskeletal imaging. Pediatr Radiol. 2009;39(Suppl 3):372–81. 19. Khanna PC, Thapa MM.  The growing skeleton: MR imaging appearances of developing cartilage. Magn Reson Imaging Clin N Am. 2009;17:411–21. 20. Kothary S, Rosenberg ZS, Poncinelli LL, Kwong S. Skeletal development of the glenoid and glenoid-coracoid interface in the pediatric population: MRI features. Skelet Radiol. 2014;43:1281–8. 21. Laor T, Jaramillo D. MR imaging insights into skeletal maturation: what is normal? Radiology. 2009;250:28–38. 22. Murphy DT, Moynagh MR, Eustace SJ, Kavanagh EC. Bone marrow. Magn Reson Imaging Clin N Am. 2010;18:727–35.

49 23. Niu J, Feng G, Kong X, Wang J, Han P. Age-related marrow conversion and developing epiphysis in the proximal femur: evaluation with STIR MR imaging. J Huazhong Univ Sci Technolog Med Sci. 2007;27:617–21. 24. Parfitt AM, Travers R, Rauch F, Glorieux FH. Structural and cellular changes during bone growth in healthy children. Bone. 2000;27:487–94. 25. Thapa MM, Iyer RS, Khanna PC, Chew FS.  MRI of pediat ric patients: part 1, normal and abnormal cartilage. AJR Am J Roentgenol. 2012;198:W450–5. 26. Vande Berg BC, Malghem J, Lecouvet FE, Maldague B. La moelle osseuse normale: aspects dynamiques en imagerie par résonance magnétique. J Radiol. 2001;82:127–35. 27. Varich LJ, Laor T, Jaramillo D.  Normal maturation of the distal femoral epiphyseal cartilage: age-related changes at MR imaging. Radiology. 2000;214:705–9. 28. Zbojniewicz AM, Laor T.  Focal periphyseal edema (FOPE) zone on MRI of the adolescent knee: a potentially painful manifestation of physiologic physeal fusion? AJR Am J Roentgenol. 2011;197:998–1004. 29. Zember JS, Rosenberg ZS, Kwong S, Kothary SP, Bedoya MA. Normal skeletal maturation and imaging pitfalls in the pediatric shoulder. Radiographics. 2015;35:1108–22. 30. Zwick EB, Kocher R.  Growth dynamics in the context of pediatric sports injuries and overuse. Semin Musculoskelet Radiol. 2014;18:465–8.

3

Imaging of Juvenile Idiopathic Arthritis

3.1

Introduction

The umbrella term juvenile idiopathic arthritis (JIA) encompasses a heterogeneous group of chronic arthritides that share the following features: (1) disease onset before 16 years of age and (2) a minimum duration of 6 weeks. It is the most common rheumatic entity of childhood, consisting of an autoimmune inflammatory disease of unknown etiology whose main target tissue is the synovium. The knee is the most common site of involvement, followed by the ankle, wrist, and hand. Even though the diagnosis is essentially a clinical one, recent therapeutic advances have drastically changed the role of imaging in its management, given that children with JIA must be diagnosed as soon as possible for timely introduction of treatment (“window of opportunity”). Early recognition and rapid attaining of disease remission are crucial for a benign course and improved long-term outcome. Overall, magnetic resonance imaging and ultrasonography are especially useful for early diagnosis and monitoring of patients with JIA, allowing prompt demonstration of abnormal findings, evaluation of disease progression, and accurate assessment of treatment response. Nevertheless, one should have in mind that widespread use of advanced imaging studies in patients with JIA is still relatively recent, and interpretation is hampered by gaps in knowledge and lack of standardization regarding the normal appearance of the growing skeleton; therefore, differentiation between normal findings and pathologic changes can be challenging, particularly in early disease. The following topics in this chapter cover the imaging findings of peripheral joint disease in JIA. Juvenile spondyloarthritis is discussed in Chap. 4, while spinal involvement in JIA is part of the subject matter of Chap. 12.

3.2

Radiographs

For many decades, radiographs were the only imaging modality available for the assessment of patients with JIA. The accumulated experience with this method is quite vast, and radiographic findings in advanced disease are characteristic. Nevertheless, radiographs are fairly insensitive for the early stages of arthritis in general, underestimating the real severity of joint damage. Therefore, they are not appropriate for early diagnosis, as detection of articular inflammation must be achieved before the onset of radiographically detectable changes. This lack of sensitivity is particularly true for JIA because the epiphyseal cartilage of the long bones is thick, so that extensive cartilaginous loss must occur before bone erosions become apparent in children. Despite these limitations, radiographs should be obtained in all patients as part of the initial assessment as a baseline study, being also useful to rule out alternative causes of joint pain. Furthermore, they are also helpful in the assessment of patients with established disease and unexpected clinical changes. Early-stage changes, such as synovial thickening and joint effusion, appear on radiographs as non-specific soft-­ tissue swelling and obliteration of fat planes (Fig.  3.1). Periarticular soft-tissue swelling is more evident if the joint is surrounded by air and a natural density gradient is therefore present (Fig. 3.2). Findings related to chronic inflammation and hyperemia include juxtaarticular osteoporosis (Fig. 3.3), epiphyseal remodeling, and increased size of secondary ossification centers (Fig.  3.4). The hyperemic state may also lead to accelerated skeletal maturation and discrepancy between bone age and chronological age. Bone overgrowth and/or early closure of the growth plates (Figs. 3.4,

© Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_3

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52 Fig. 3.1  Radiographs of the ankle (a) and of the knee (b) of two distinct children with JIA showing soft-tissue swelling and displacement of periarticular fat planes. Even though bone erosions are not apparent, osteoporosis is already present, notably in the knee, where soft-tissue swelling is much more prominent

3  Imaging of Juvenile Idiopathic Arthritis

a

b

3.2 Radiographs

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3.5, 3.6, and 3.7) can be found, as well as limb-length discrepancy (Fig. 3.8). Synovitis is present since the very early stages of JIA, with gradual development of synovial hyperplasia and hypercellular pannus. The so-called joint space seen on radiographs comprises, in fact, the joint cavity itself and non-calcified structures (which are cartilaginous for the most part) interposed between the osseous surfaces. This space undergoes

Fig. 3.2  Radiograph of the right hand of a child with JIA.  There is soft-tissue swelling adjacent to the proximal interphalangeal joint of the fifth finger, more evident due to the density gradient created by the air and/or fat interface. Periarticular osteoporosis and periosteal reaction along the diaphyses of the proximal phalanges are also present

Fig. 3.3  Radiographs of the hands and wrists of a child with early-stage JIA. Symmetric and bilateral periarticular osteoporosis is the main finding, predominantly found in the metacarpophalangeal joints. There is also subtle increase in the size of the epiphyses, mainly in the left wrist, without signs of erosive articular disease

Fig. 3.4  Radiograph of the pelvis of a patient with long-standing JIA displaying findings related to chronic hyperemia. The proximal epiphysis of the right femur shows increased size, while there is diffuse osteoporosis associated with hypoplasia of the iliac bones and premature physeal closure on the left. Bilateral coxa valga is also present

54 Fig. 3.5  Radiograph of the hands of a patient with long-standing JIA (a) discloses deformities of several digits related to premature and asymmetric closure of the growth plates, with shortening of the second to the fifth metacarpals on the right and of the distal phalanges of both thumbs. Diffuse osteoporosis is also present, with abnormal alignment of the carpal bones and increased size of several epiphyses, bilaterally. Narrowing of joint spaces is obvious, mainly in the right radiocarpal joint, with invagination of the adjacent carpal bones. In (b), in another child with late-stage JIA, there is growth arrest due to premature physeal closure in both elbows. Marked periarticular osteoporosis is also present, with increased size of the distal humeral epiphyses, notably in the left elbow

3  Imaging of Juvenile Idiopathic Arthritis

a

b

3.2 Radiographs Fig. 3.6  In (a), anteroposterior view shows asymmetric growth of the knees, with increased size of the left distal femur when compared to the contralateral one (which also displays mild overgrowth); diffuse osteoporosis and growth recovery lines are also present, bilaterally. In (b), only the left knee is affected, with epiphyseal overgrowth of the distal femur and proximal tibia and mild ipsilateral osteoporosis; growth recovery lines are also present

55

a

b

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Fig. 3.7  The left image reveals asymmetric bone maturation in the knees of a child with JIA: the epiphyses of the right femur, tibia, and fibula are irregular, bigger, and more developed than the contralateral ones, and regional osteoporosis is also present. In the right image, there

a

Fig. 3.8  Scanogram of an adolescent with advanced JIA (a) demonstrating advanced bilateral hip arthritis, more important on the left side, with joint space narrowing, widespread erosions, and remodeling of the joint surfaces. There is shortening of the right limb, with marked leg-­ length discrepancy. Growth recovery lines and periarticular osteoporo-

is diffuse osteoporosis of the right elbow, as well as marked periosteal reaction along the distal humerus and epiphyseal overgrowth. Erosive articular disease is evident, mainly in the medial portion of the joint, as well as soft-tissue swelling

b

sis can be seen in the knees and ankles. Anteroposterior view of the legs of another patient with JIA (b) shows diffuse osteoporosis and increased size of the epiphyses of the knees and ankles; the left limb is shorter than the contralateral as a result of abnormalities above the knee level. Tibiotalar slant is evident bilaterally

3.2 Radiographs

57

Fig. 3.9  Radiograph of the left wrist of a 16-year-old female with JIA since late childhood. There is mild osteoporosis, with narrowing of the radiocarpal joint space and disorganization of the proximal carpal row; a small cortical erosion can be seen in the distal third of the scaphoid. Despite the absence of extensive bone erosions, these findings are indicative of advanced cartilaginous destruction

Fig. 3.11  Radiograph of the right knee of an adolescent with JIA and erosive changes. A large peripheral bone erosion can be seen in the proximal tibia, sparing the joint surface of the adjacent plateau

Fig. 3.10  Long-standing JIA affecting both hips, with bone erosions, narrowing of the joint spaces (more important in the right hip), and periarticular osteoporosis. Periosteal reaction is seen along the right femoral neck

slow, progressive, and uniform narrowing due to the action of pannus, which erodes and destroys the cartilaginous structures and the bone (Figs. 3.9 and 3.10). Bone erosions are first seen in peripheral sites where the articular cartilage is absent (“bare areas”), near to ligament insertions and capsular reflections (Fig. 3.11), presenting centripetal progression. Erosions in the joint surfaces are indicative of advanced disease, which may ultimately lead to secondary osteoarthritis (Figs.  3.8, 3.10, 3.12, and 3.13). Destruction of the joint surfaces may eventually cause ankylosis, which is relatively infrequent nowadays (Fig. 3.14). Periosteal reaction is more frequently

Fig. 3.12  Radiograph of the left shoulder of a patient with long-­ standing JIA. The joint surface of the humeral head is markedly irregular due to the presence of bone erosions. Cephalic migration of the humeral head is also present, related to complete tear of the rotator cuff. Glenoid deformity and bone remodeling are also present

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a

b

Fig. 3.13  In (a), radiograph of the left hip of a patient with advanced JIA demonstrates erosive arthropathy and secondary osteoarthritis due to extensive cartilaginous damage, with marked narrowing of the joint space associated with marginal osteophytes and subchondral sclerosis.

In (b), radiographs of the left elbow of a 22-year-old male who suffered from JIA since age 1 year reveal premature and extensive osteoarthritis secondary to chronic arthritis

Fig. 3.14  Radiographs of the wrists of a 6-year-old child with JIA since 18  months old. There is diffuse osteoporosis and ankylosis of multiple joints, mainly carpometacarpal, as well as bilateral arthritis of

the fourth metacarpophalangeal joints, abnormal bone modeling, and solid periosteal reaction along the metacarpal diaphyses

3.2 Radiographs

encountered in JIA than in the adult form of rheumatoid arthritis, affecting mostly the tubular bones of the hands and feet (Figs.  3.2, 3.7, 3.10, 3.14, and 3.15). Bone spurs and enthesophytes are associated with enthesopathy (inflammation involving the sites of insertion of tendons, ligaments, and joint capsules) in patients with the enthesitis-­related form of JIA. In advanced JIA, the association of diffuse osteoporosis (Fig. 3.16) and anomalous biomechanics caused by changes such as muscle atrophy and abnormal joint alignment increases the risk of fractures. Radiodense metaphyseal bands can be found in patients to whom bisphosphonates were administered to treat osteoporosis (Fig. 3.17). Growth recovery lines are frequently seen (Figs. 3.6, 3.8, and 3.16), mostly in patients with long-standing disease, as well as the “bone-within-bone” appearance, which has a similar meaning (Fig. 3.18). Intraarticular and periarticular soft-­tissue calcifications are also common, most often secondary to therapeutic injections of corticosteroids (Fig. 3.19). Flexion contractures, varus and/or valgus deformities, and altered joint alignment are late-stage complications (Fig. 3.20). Classic radiographic findings in late-stage JIA of the hands and wrists include crowding, altered shape (“squaring”) and disorganization of the carpal bones, as well as epiphyseal deformities and brachydactyly (Figs.  3.5, 3.14, and 3.21). Radial deviation of the affected fingers is more Fig. 3.15  Symmetric and bilateral periostitis can be seen along the proximal and middle phalanges in both hands, notably from the second to the fourth digits. Periarticular osteoporosis is also present in this patient with JIA

59

common than the ulnar deviation characteristic of adult-type rheumatoid disease, even though the typical digital deformities commonly found in advanced rheumatoid arthritis  – namely, “swan neck” (hyperextension of the proximal interphalangeal joint and flexion of the distal interphalangeal joint) and “boutonnière” (hyperflexion of the proximal

Fig. 3.16  There is marked widespread osteoporosis in both ankles in this patient with long-standing JIA, as well as soft-tissue swelling and growth recovery lines

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3  Imaging of Juvenile Idiopathic Arthritis

Fig. 3.18  Detail of a pelvic radiograph showing the classic “bone-­ within-­bone” appearance in the right iliac bone of an adolescent with long-standing JIA

Fig. 3.17  This 14-year-old female with JIA developed diffuse osteoporosis after institution of systemic corticosteroid therapy, and treatment with oral alendronate was then started. Radiographs taken 10 months later disclosed dense metaphyseal bands in his long bones, here shown in the left ankle. Tibiotalar slant is also evident

interphalangeal joint with extension of the distal interphalangeal joint) – can also be found in JIA. Common findings in the knees include widening of the intercondylar notch (Fig. 3.22) and “squaring” of the patella (Fig. 3.23), similar to those found in hemophiliac children. Tibiotalar slant (medial inclination of the articular surfaces of the ankle) is another finding that can be seen both in JIA and in hemophilia (and in other conditions as well – Figs. 3.8 and 3.17). Pelvic abnormalities include iliac hypoplasia (Figs. 3.4 and 3.24), abnormal cervical-diaphyseal angle (Fig. 3.4), acetabular protrusion (Fig. 3.25), avascular necrosis of the femoral head (Fig.  3.26), and premature osteoarthritis of the hip (Figs. 3.13 and 3.24). Temporomandibular arthritis is not infrequent in JIA and may be severe (Fig. 3.27), with damage to the growth center of the mandibular condyle, condylar flattening, bone erosions, and facial deformities. Complications related to JIA of the temporomandibular joints comprise micrognathia and

Fig. 3.19  Striated calcifications are seen in the infrapatellar fat pad of a young adult with late-stage sequelae of JIA who underwent several procedures for steroid infiltration in the knee. The radiographic findings and the clinical data are highly characteristic about the nature of these calcifications, with no need for further investigation

3.2 Radiographs

a

61

b

c

Fig. 3.20  In the patients above, in addition to diffuse osteoporosis and radiographic evidence of arthritis, there is flexion deformity of the left elbow (a), both knees (b), and the first metatarsophalangeal joint of the left foot (c). In (d), deformity of the heads of the first metacarpals and

d

subluxation of the corresponding metacarpophalangeal joints are evident, more important in the right hand, as well as epiphyseal overgrowth

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3  Imaging of Juvenile Idiopathic Arthritis

a

Fig. 3.21  Typical radiographic findings in the hands and wrists of two distinct patients with long-standing JIA. There are joint space narrowing and crowding of the carpal bones, which present a polyhedral appearance, opposite to the rounded contours that they exhibit in nor-

a

b

mal children. Diffuse osteoporosis can be seen in both patients, with carpal and metacarpal erosions in (a) and increased size of the epiphyses of the distal forearm in (b)

b

c

Fig. 3.22  Radiographs of the knees of three different patients with JIA (a–c). Osteoporosis, epiphyseal remodeling, and widening of the intercondylar notch are found in varied degrees of severity in all of them. Bone erosions are also seen, more evident in (b)

3.2 Radiographs

63

Fig. 3.24  Severely destructive arthropathy of the right hip is evident in this 36-year-old patient with late-stage sequelae of JIA. There is diffuse hypoplasia of the homolateral iliac bone, related to long-standing disease, as well as generalized osteoporosis in the affected hemipelvis

Fig. 3.23  Lateral view of the left knee of a patient with long-standing JIA showing diffuse osteoporosis, markedly increased epiphyseal size, soft-tissue swelling, and patellar “squaring.” These findings may be indistinguishable from those associated with hemophilia

Fig. 3.25  Aggressive arthritis affecting the left hip in a poorly controlled patient with long-standing JIA.  Anteroposterior radiograph displays advanced joint destruction, with abnormal shape and irregular contour of the femoral head, bone remodeling, and acetabular protrusion

Fig. 3.26  Avascular necrosis of the femoral head is a well-known complication of JIA. Anteroposterior (left) and lateral (right) radiographs evidence osteonecrosis of the left femoral head, with bone remodeling,

abnormal epiphyseal shape, widening and shortening of the femoral neck, and subchondral lucencies. A small erosion can be seen in the right femoral head, with ipsilateral coxa valga

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3  Imaging of Juvenile Idiopathic Arthritis

Fig. 3.27  Planigraphy of the right temporomandibular joint (open mouth) of a patient with JIA revealing late-stage arthritic changes, with extensive destruction of the mandibular condyle, bone fragmentation, and erosions of the joint surfaces. Remodeling and enlargement of the glenoid fossa are quite evident, as well as sclerosis of the subchondral bone and flattening of the temporal eminence

retrognathia, malocclusion, reduced joint mobility, abnormal dentition, and shortening of the mandibular body and rami, with “bird-like” facies and secondary degenerative changes in advanced cases. As radiographic changes are related to structural damage, early detection of temporomandibular joint involvement is crucial and can be achieved with magnetic resonance imaging (see Sect. 3.4).

3.3

Ultrasonography

Ultrasonography (US) is more sensitive than radiographs for the assessment of initial JIA, demonstrating abnormalities related to early-stage articular inflammation such as joint effusion and synovitis. Furthermore, US is superior to clinical evaluation in the identification of synovitis and in distinguishing joint disease from tenosynovitis. However, there is a strong dependence on the operator’s skills and on the type of equipment used in pediatric musculoskeletal US. Therefore, a well-trained physician acquainted with the peculiarities and pitfalls of the immature skeleton and an appropriate US machine are required in order to obtain useful and reliable information. Physiologic irregularities of newly ossified epiphyses, for example, may be misconstrued as cortical erosions, and the thickness and vascularity of epiphyseal cartilage vary with skeletal maturation; in addition, synovial Doppler signal and variable amounts of

intraarticular fluid may be present in healthy children, so that sometimes it may be challenging to define what is normal and what is not, even for the experienced operator. In addition, the role of US in the detection of bone erosions in JIA is less well established than in rheumatoid arthritis, and magnetic resonance imaging outperforms US both in the detection of erosive changes and in the characterization of pre-erosive changes (bone marrow edema and/or osteitis) in patients with JIA. On the other hand, US is very adequate for guidance of diagnostic (aspiration) and therapeutic (injection) joint procedures in children. Joint effusion appears hypoechogenic and/or anechogenic, compressible, occasionally with suspended debris, and does not exhibit Doppler signal, while the inflamed synovium is hypoechogenic (even though sometimes it may be isoechogenic or ­hyperechogenic), thickened, and poorly compressible, with increased flow on Doppler images (Fig. 3.28). Serial studies are useful for monitoring disease evolution and to assess response to treatment: good evolution will lead to involution of joint effusion and synovial thickening and/or hyperemia, while the opposite happens in poorly responsive patients (Fig. 3.29). Taking into account the operator-dependent nature of US and the lack of standardized protocols, serial studies should be ideally performed by the same sonographer. Persistent synovitis has been detected both by US and magnetic resonance imaging in a large proportion of JIA patients considered in remission and with inactive disease on clinical grounds. The implications of this finding are still unclear, and further clarification is needed before stating that subclinical synovitis is associated with a higher risk of structural damage progression or should influence decisions about therapy. Tenosynovitis is most commonly seen around the ankle joint and involving the extensor tendons of the wrist. The tenosynovial component of JIA is particularly well assessed with US, which is able to evaluate the structure of the tendons – which may be thickened and heterogeneous if tendinopathy is present – and the presence of fluid and thickened synovium within their sheaths, as well as increased synovial Doppler signal (though the latter is not mandatory for the diagnosis) (Figs. 1.7 and 3.30). Extension of the inflammation to adjacent bursae and synovial cysts (such as popliteal cysts, which are particularly common in JIA) is usually evident on US (Fig.  3.28). The hypertrophic synovium may undergo fibrinoid necrosis, resulting in the formation of the so-called rice bodies, which appear as hypoechoic nodules that typically measure a few millimeters in size. The normal articular cartilage is hypoechogenic, smooth, and well-delimited. The inflamed cartilage, however, becomes thickened, irregular, and ill-defined; cartilaginous thinning and erosions can be seen in more advanced stages. US is superior to radiographs for the detection of superficial bone erosions in sites where acoustic windows are available, appearing as focal cortical defects that can be seen in two

3.3 Ultrasonography

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65

b

c

Fig. 3.28  In (a), US of the knees (suprapatellar pouches, upper row) and of the ankles (lower row) of a child with JIA reveals heterogeneous joint effusions in these joints associated with bilateral and symmetric synovial thickening. In (b), US of another patient with JIA discloses a popliteal cyst containing heterogeneous fluid and marked synovial

thickening; the thickened synovium displays prominent hyperemia on Doppler US in (c). (Courtesy of Dr. Telma Sakuno, MD, Hospital Universitário da UFSC, Florianópolis, Brazil (a) and Dr. Maria Montserrat, MD, Clínica Montserrat, Brasília, Brazil (b and c))

Fig. 3.29  US of the anterior recess of the left ankle (upper row) and of the suprapatellar pouch of the right knee (lower row) of a 3-year-old female with JIA. There is thickening of the synovium (open arrows) and joint effusion in both joints, but no abnormal synovial Doppler signal

was found. The suprapatellar pouch is completely filled by hyperechogenic and hypertrophic synovium. This child had a recent flare of disease activity and was being reevaluated after showing clinical improvement upon treatment

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Fig. 3.29 (continued)

perpendicular planes, presenting irregular floor and posterior acoustic enhancement. Enthesitis, when present, appears as loss of the normal fibrillary structure and decreased echogenicity of a tendon – or a ligament – at its bone attachment. The affected tendon and/or ligament may appear thickened, and increased Doppler signal and/or increased fluid in adjacent bursae may be present as well. The most often involved entheses in JIA include the plantar aponeurosis, the insertion of the Achilles tendon, the distal and proximal insertions of the patellar tendon, and the insertion of the quadriceps. Entheseal calcifications, enthesophytes, and erosions may be also found in later stages, although these findings are less commonly seen in children.

3.4

Fig. 3.30  Tenosynovitis of the extensor tendons of the right wrist in an 11-year-old male with JIA.  The upper image displays a longitudinal scan along the third extensor compartment, while the lower image is a transversal section highlighting the fourth compartment. Both images show a hypoechogenic and heterogeneous halo surrounding the tendons (calipers and arrows), which maintain normal thickness and echogenicity. Histopathological analysis of the hypoechogenic tissue showed chronic hypertrophic synovitis

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is the imaging method of choice for early diagnosis of JIA, mostly because of its multiplanar capabilities, high resolution, and exquisite anatomic detail, allowing excellent evaluation of the soft tissues and the bone. MRI is the only imaging modality that assesses all relevant structures in JIA, providing accurate evaluation of the extent of synovitis and bone marrow and soft-tissue edema and reliable depiction of early erosive disease. Intravenous gadolinium is formally indicated when imaging patients with JIA in order to assess the real extent and the severity of arthritis, as well as to monitor its evolution in subsequent studies. Joint effusion usually displays low signal intensity on T1-weighted images (T1-WI) and high signal intensity on T2-weighted images (T2-WI) (Figs. 3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, and 3.39); increased signal intensity on T1-WI and/or decreased signal on T2-WI are indicative of

3.4 Magnetic Resonance Imaging

a

67

b

Fig. 3.31  Transverse T2-WI (a) and post-gadolinium fat sat T1-WI (b) of the hips of a 9-year-old female with long-standing JIA affecting both knees and arthritis of recent onset in the right hip. It is easier to identify right-­sided small to moderate joint effusion and synovial thickening by

comparing the abnormal hip with the contralateral normal one. Synovitis is even more evident on (b), appearing as a thin enhancing stripe easily distinguished from the dark synovial fluid. Osteitis and erosions are not yet present

Fig. 3.32  Contrast-enhanced fat sat T1-WI of the knees in the transverse and coronal planes (right knee, upper row; left knee, lower row) of a 7-year-old male with JIA since age 4. Symmetric and bilateral joint effusion and synovial thickening are evident, notably in the left knee. The thickened synovium shows enhancement and is more prominent in

the intercondylar notches and adjacent to the lateral meniscus of the left knee. Meniscal hypoplasia is also seen in both knees, affecting predominantly the medial menisci. Focal irregularities can be seen in the corners of the tibial epiphyses on coronal images, corresponding to tiny cartilaginous erosions

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3  Imaging of Juvenile Idiopathic Arthritis

hemarthrosis. The inflamed synovium appears thickened and irregular, most often hypointense on T1-WI and hyperintense on T2-WI; nevertheless, the hallmark feature of active arthritis is abnormal enhancement of thickened synovium, which appears on contrast-enhanced fat sat T1-WI as a bright stripe against the dark background (Figs.  3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, 3.39, and 3.40). It has been recently shown that synovial thickening is commonly p­ resent in the knee of children unaffected by clinical arthritis; however, synovitis involving the infrapatellar region and adjacent to the cruciate ligaments is considered highly suggestive of JIA, so that these findings increase the ability to discriminate between JIA and benign synovial thickening (Fig. 3.40).

Synovial enhancement may be patchy, particularly in chronic disease, related to nonenhancing areas of fibrosis. “Rice bodies” appear at MRI as non-enhancing micronodules with intermediate to low signal intensity in all sequences inside the joint cavity. Progression or involution of synovitis and joint effusion in serial studies provide information about disease evolution and treatment response, just like in US, and assessment of disease activity and differentiation between active synovitis and fibrotic changes can be done by evaluating the pattern of synovial enhancement. Prominent periarticular lymph nodes that may enhance on post-contrast images are not uncommon, frequently found in the popliteal fossa (Figs.  3.34, 3.35, 3.38, and 3.40). Whole-body MRI

a

Fig. 3.33  MRI of the left ankle of a child with JIA.  In (a), images obtained in multiple spatial planes and using different sequences reveal synovitis, bone erosions (more evident in the tarsal sinus, with adjacent bone marrow edema), and joint effusion. In (b), gadolinium-enhanced fat sat T1-WI display enhancement of the inflamed synovium (allowing

it to be distinguished from the synovial fluid), within bone erosions and in the edematous bone. Tenosynovitis is quite obvious, with fluid distension and contrast enhancement within the sheaths of the fibular tendons and of the posterior tibial tendon. Enhancement of the retrocalcaneal bursa is also evident

3.4 Magnetic Resonance Imaging

69

b

Fig. 3.33 (continued)

a

Fig. 3.34  Sagittal fat sat T2-WI of the left knee of a child with JIA (a) disclosing a large joint effusion associated with synovial thickening and prominent lymph nodes in the popliteal fossa, posterior to the distal femoral diaphysis, without evidence of erosive arthritis. In another

b

patient, post-contrast fat sat T1-WI of the right knee (b) reveal enlarged, enhancing lymph nodes in the popliteal fossa, as well as marked synovitis and joint effusion

70

has been described as a potentially useful tool in the search for active inflammatory lesions in JIA but still lacks study and validation. MRI is able to demonstrate from subtle irregularities of the articular cartilage, seen in early-stage JIA (Figs.  3.32, 3.35, and 3.41), to clear-cut erosions and large areas of

3  Imaging of Juvenile Idiopathic Arthritis

osteochondral destruction, which are characteristic of advanced disease (Figs.  3.37 and 3.39). After intravenous injection of gadolinium, inflamed cartilages usually display some degree of enhancement (Fig. 3.35), sometimes with a “spoke-wheel” pattern of prominent epiphyseal vessels (Fig. 3.42). Subchondral areas of bone marrow edema appear

a

Fig. 3.35  Transverse fat sat T2-WI (upper row, a) and post-gadolinium fat sat T1-WI in the transverse (lower row, a) and sagittal (b) planes of the right knee of a child with JIA.  T2-WI demonstrate joint effusion, synovial thickening, and small cartilaginous erosions in the femoral trochlea and in the femoral condyles, with thinning of the cartilage of the

lateral condyle. Contrast-enhanced images show that the synovial thickening is even more extensive than initially estimated as the inflamed synovium can be distinguished from the synovial fluid. Enhancement is also seen in the inflamed cartilages (which present irregular surfaces and superficial erosions) and in popliteal lymph nodes

3.4 Magnetic Resonance Imaging

71

b

Fig. 3.35 (continued)

a

Fig. 3.36  5-year-old female with JIA and active arthritis in the right wrist. In (a), coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) reveal extensive bone marrow edema affecting several carpal bones and the second metacarpal, with variable post-contrast enhancement, as well as joint effusion and an abnormally thickened and enhancing synovium. In (b), axial fat sat T2-WI (left) and post-­gadolinium fat sat T1-WI (right) disclose tenosynovitis of the extensors characterized by peritendinous edema and post-contrast enhancement affecting mostly the first and the second compartments; involvement of the extensor carpi ulnaris is more evident in post-gadolinium images. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)

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3  Imaging of Juvenile Idiopathic Arthritis

b

Fig. 3.36 (continued)

Fig. 3.37  19-year-old male with long-standing JIA and arthritis of the left hip. Coronal STIR image (left) and axial post-gadolinium fat sat T1-WI (right) show markedly thickened synovium occupying the joint cavity (asterisks), with post-contrast enhancement. There is also exten-

sive thinning of the articular cartilages, more evident in the uppermost portion of the joint. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)

3.4 Magnetic Resonance Imaging

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Fig. 3.38 Young child with well-controlled JIA presenting with signs of inflammation in the left knee. Sagittal T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) disclose deep infrapatellar bursitis characterized by fluid distension of the bursa and

Fig. 3.39  In (a), coronal STIR image (left) and post-gadolinium fat sat T1-WI (right) of the left wrist of an 18-year-old female with long-standing JIA display arthritis of the left wrist, with osteitis of the bones of the proximal carpal row, a large erosion of the distal scaphoid, and marked synovitis of the radiocarpal and distal radioulnar joints (note the difference on T1-WI between the thickened and abnormally enhancing synovium, which is peripherally located, and the centrally situated dark, non-enhancing joint fluid in the latter compartment). Thickening of the extensor carpi ulnaris and peritendinous postcontrast enhancement are also present, representing tendinopathy and/or tenosynovitis. In (b), axial fat sat T2-WI (left) and sagittal postgadolinium fat sat T1-WI (right) of the right shoulder of a 15-year-old female with JIA show marked synovial thickening inside the joint and prominent post-gadolinium enhancement; the synovial fluid in the subscapularis recess does not enhance. (Both cases courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)

a

b

marked synovial thickening and post-contrast enhancement. Mild intraarticular synovitis is also present, as well as enhancing lymph nodes in the popliteal fossa (right image)

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3  Imaging of Juvenile Idiopathic Arthritis

Fig. 3.40  Sagittal fat sat T2-WI (left) and post-­ gadolinium fat sat T1-WI (right) of the right knee of an 11-year-old male with JIA displaying small joint effusion and synovial enhancement inside the joint cavity and in the vicinity of the cruciate ligaments, with no signs of osteitis or erosions. An enhancing lymph node can be seen in the popliteal region. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)

Fig. 3.41  Imaging investigation of the right knee of a child with early JIA. Even though the lateral radiograph is entirely normal (first image), sagittal T1-WI (second image) and fat sat T2-WI (third image) clearly demonstrate a small joint effusion and a cartilaginous erosion affecting

the posterior aspect of the epiphyseal cartilage of the medial femoral condyle, as well as osteitis and early erosive changes of the subchondral bone; a focal defect of the overlying articular cartilage was also present (not shown)

3.4 Magnetic Resonance Imaging

75

as ill-defined zones of low signal intensity on T1-WI and increased signal intensity on T2-WI, which are more evident on fluid-sensitive sequences, indicative of osteitis and active inflammation (Figs. 3.43, 3.44, and 3.45); such areas commonly exhibit post-contrast enhancement long before the

development of bone erosions. Bone erosions, in turn, are well-delimited cortical defects that are most often hypointense on T1-WI and hyperintense on T2-WI, frequently surrounded by bone marrow edema and displaying post-gadolinium enhancement when active (Figs. 3.41, 3.46,

Fig. 3.42  Transverse post-gadolinium fat sat T1-WI of the right knee of a 4-year-old male with JIA. Joint hyperemia led to prominence of epiphyseal vessels of the proximal tibia, causing this bizarre pattern of cartilaginous enhancement

Fig. 3.43  Coronal fat sat PD-WI of the hips of a 19-year-old female with long-standing JIA. There is joint effusion in the right hip, as well as bone marrow edema in the ipsilateral proximal femur and in the subchondral bone of the corresponding acetabulum (compare with the normal left hip). A focal area of subcortical osteitis is seen in the lateral aspect of the right head and/or neck transition, without associated erosions

Fig. 3.44  MRI of the left ankle of a child with early JIA. Sagittal fat sat T2-WI (upper left image) reveals a mottled pattern of bone marrow edema affecting the tarsal bones and a small tibiotalar joint effusion. Sagittal (upper right image) and transverse (lower images) post-­

gadolinium fat sat T1-WI show enhancement of the edematous bone and of the inflamed synovium, as well as irregularity of the cartilage of the posteromedial portion of the talar dome. Only MRI is able to show these early findings with such a high level of detail

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Fig. 3.44 (continued)

Fig. 3.46  Transverse T2-WI (upper image) and T1-WI (lower image) of the right hip of a patient with JIA. In addition to joint effusion, there are large bone erosions in the femoral head, filled with thickened synovium and synovial fluid

Fig. 3.45  Sagittal fat sat T2-WI of the left ankle of an adolescent with JIA. In addition to joint effusion, extensive bone marrow edema affecting several tarsal bones is also evident, as well as soft-tissue edema in the dorsum of the foot, findings compatible with tarsitis. Despite the extent of bone marrow edema, bone erosions are absent

3.4 Magnetic Resonance Imaging Fig. 3.47  Advanced arthritis of the left hip of a 22-year-old patient with JIA since mid-adolescence. Anteroposterior view (a) discloses marked narrowing of the joint space of the left hip, as well as abnormal shape of the femoral head and bone erosions. These findings are accurately depicted with MRI (b, coronal T1-WI [left] and post-gadolinium fat sat T1-WI [right]), which discloses extensive cartilaginous destruction, bone erosions, joint incongruity, and secondary osteoarthritis. Post-­ gadolinium enhancement is indicative of active inflammation

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and 3.47). Bony depressions are commonly seen in the carpal bones of children and may be difficult to differentiate from erosions in JIA; the presence – or absence – of additional signs of inflammation, such as active synovitis and associated cartilage thinning, is useful to discriminate benign findings from actual erosions. Changes related to joint hyperemia, such as increased size and altered shape of the epiphyses, premature physeal closure, and secondary osteoarthritis are also clearly seen on MRI (Figs. 3.48 and 3.49).

On MRI, inflamed entheses present bone marrow edema, edema of the adjacent soft tissues, distension of nearby bursae, and post-gadolinium enhancement, even though enthesophytes and bone spurs are better seen on radiographs (Fig. 3.50). Tarsitis is a peculiar presentation of patients with enthesitis-related JIA that also occurs in juvenile spondyloarthritis, characterized by inflammation of the small joints of the midfoot and the overlying tendons, entheses, and soft tissues; MRI reveals synovitis, joint effusions, bone marrow

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Fig. 3.48  Sagittal T1-WI (upper images) and fat sat T2-WI (lower images) of the left knee of a young adult with long-standing JIA. There is marked increase in the size of the patella, whose bone marrow is diffusely edematous. In addition, joint effusion and synovitis are also present, with erosions of the femoropatellar joint surfaces

edema, and soft-tissue edema (Fig.  3.45). Inflammation within synovial cysts and periarticular bursae may be found as well, with fluid distension and synovial thickening and/or enhancement (Figs. 3.38 and 3.51). MRI is also invaluable in the assessment of patients with enthesitis-related JIA and involvement of the sacroiliac joints (imaging of sacroiliitis is discussed in further detail in Chap. 4). As stated above, tenosynovitis affects more frequently the extensor tendons in the wrists and the ankles (even though flexor tendons may be involved too), with fluid distention, synovial thickening, and post-gadolinium enhancement in the affected tendon sheaths (Figs. 1.30, 3.33, 3.36, and 3.39); inflamed tendons appear thickened and display

increased signal intensity, and intratendinous post-gadolinium enhancement may be present as well. Long-standing inflammatory tendinopathy can evolve into degeneration and rupture of the tendons. Muscle atrophy and fatty replacement are typical of chronic disease, as well as hypoplasia of the cruciate ligaments and menisci (Figs. 3.32 and 3.49). The temporomandibular joints (TMJ) are frequently affected in JIA (50–87% of all patients, mostly those younger than 4 years old). TMJ involvement in JIA has gained increased attention in the literature in recent years as it is often present at the beginning of the disease, can be asymptomatic even in the presence of erosive arthritis, and may be

3.4 Magnetic Resonance Imaging

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a

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c

Fig. 3.49  Imaging investigation of the right knee of a 9-year-old female with active JIA. In (a), anteroposterior views of both knees demonstrate increased size of the epiphyses of the right distal femur and proximal tibia (compare with the normal left knee). In addition to

epiphyseal enlargement, fat sat PD-WI in the coronal (b) and sagittal (c) planes disclose joint effusion and synovial thickening, as well as mild hypoplasia of the medial meniscus. Erosions and subchondral osteitis are absent

the first  – and, sometimes, the only  – affected joint. The younger the child is at the onset of the disease, the more severe mandibular growth abnormalities are, so that early diagnosis is essential in order to prevent structural damage (see Sect. 3.2). Clinical assessment is often difficult, and imaging is the most reliable tool for evaluation of TMJ arthritis. MRI is the imaging modality of choice, and acute findings include joint effusion, synovitis, and bone marrow

edema. Chronic changes include pannus formation, condylar flattening, bone erosions, disk abnormalities, and hypertrophic bone formation. Post-gadolinium images are mandatory in order to differentiate joint effusion from increased signal intensity in the thickened synovium seen on fluid-sensitive sequences due to acute inflammation and edema (Fig. 3.52). US is not recommended for TMJ assessment in JIA because of its unacceptably low level of sensitivity.

80 Fig. 3.50  16-year-old male with enthesitis-related JIA. Sagittal T1-WI (left) and fat sat T2-WI (right) of the left ankle reveal a thickened and heterogeneous Achilles tendon, as well as bone marrow edema of the calcaneus adjacent to its insertion, distention of the retrocalcaneal bursa, and edema of the surrounding soft tissues, findings compatible with tendinopathy and active enthesopathy. A small tibiotalar joint effusion is also present. (Courtesy of Prof. Dr. Rodrigo Aguiar, MD, Universidade Federal do Paraná and Clínica DAPI, Curitiba, Brazil)

Fig. 3.51  Female patient with long-standing JIA. Coronal T1-WI (left) and fat sat T2-WI (right) of the right hip disclose joint space narrowing and a small joint effusion, as well as fluid distension of the trochanteric bursa. MRI and US are very suitable in the assessment of distended periarticular bursae and other fluid collections

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Fig. 3.52  Sagittal T2-WI and T1-WI of the left TMJ of a 9-year-old male with long-standing JIA in the closed-mouth position (a) show flattening of the articular surface of the mandibular condyle along with remodeling and enlargement of the glenoid fossa, as well as flattening of the temporal eminence and a small joint effusion; additionally, coronal post-gadolinium fat sat T1-WI (b) reveals bilateral synovial enhancement (arrows), more prominent in the left side. Sagittal reformatted cone-beam CT images in closed-mouth (c) and open-mouth (d)

positions disclose bilateral bone deformities (including a severely hypoplastic and dysmorphic right condyle), limited excursion of both condyles, and tiny erosions in the irregular articular surfaces of both mandibular condyles, more evident on the right side; volume-rendered reconstructions (e) display asymmetry of the mandibular rami, micrognathia and/or retrognathia, and limited jaw opening. (Courtesy of Dr. Glaucia Nize Martins Santos, DDS, MSc, Hospital de Base do Distrito Federal, Brasília, Brazil)

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c

d

Fig. 3.52 (continued)

3.5 Computed Tomography

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e

Fig. 3.52 (continued)

3.5

Computed Tomography

Even though computed tomography (CT) is excellent for bone assessment and for the detection of bone erosions, it is exceptionally requested for patients with JIA, mainly because of its limited accuracy in the evaluation of the soft tissues, exposition to ionizing radiation, and unreliable assessment of disease activity. Nevertheless, it may be occasionally used as a diagnostic alternative, especially in the study of anatomically complex joints such as the cervical spine (Chap. 12) and the TMJ (Fig. 3.52). In addition, CT is the best imaging method for the assessment of fractures, which may be occasionally present in patients with JIA.

Key Points

• Timely institution of treatment has the potential to modify the course of JIA, leading to an improved prognosis. Therefore, it is essential to diagnose the disease as early as possible, making imaging investigation more important now than ever before. • Imaging of JIA is sometimes challenging, even for experienced physicians, because skeletal changes due to normal growth may be difficult to differentiate from abnormal findings related to joint inflammation.

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• Radiographs are suitable for assessment of advanced JIA, in which osteoarticular damage is already established, and the radiographic findings of long-­ standing disease are classic. Nevertheless, this imaging method is inappropriate for early diagnosis and to monitor treatment response. • US and MRI are useful in the early stages of JIA, as both are able to detect joint effusion, synovitis, and edematous and/or hyperemic abnormalities of the soft tissues, to which radiographs are fairly insensitive. MRI is superior for the detection of bone erosions and to disclose areas of osteitis (seen as foci of subchondral bone marrow edema) that are present even in the pre-erosive stage. MRI also demonstrates articular structures not seen on US or to which the latter has limited access. • Doppler US and contrast-enhanced MRI are able to assess treatment response and disease evolution in serial studies, mostly by monitoring joint effusion and synovial inflammation.

Recommended Reading 1. Azouz EM.  Juvenile idiopathic arthritis: how can the radiologist help the clinician? Pediatr Radiol. 2008;38(Suppl 3):S403–8. 2. Babyn P, Doria AS. Radiologic investigation of rheumatic diseases. Rheum Dis Clin N Am. 2007;33:403–40. 3. Chauvin NA, Doria AS.  Ultrasound imaging of synovial inflammation in juvenile idiopathic arthritis. Pediatr Radiol. 2017;47:1160–70. 4. Chauvin NA, Khwaja A. Imaging of inflammatory arthritis in children: status and perspectives on the use of ultrasound, radiographs, and magnetic resonance imaging. Rheum Dis Clin North Am. 2016;42:587–606. 5. Collado P, Malattia C.  Imaging in paediatric rheumatology: is it time for imaging? Best Pract Res Clin Rheumatol. 2016;30:720–35. 6. Daldrup-Link HE, Steinbach L. MR imaging of pediatric arthritis. Radiol Clin N Am. 2009;47:939–55. 7. Damasio MB, de Horatio LT, Boavida P, Lambot-Juhan K, Rosendahl K, Tomà P, et al. Imaging in juvenile idiopathic arthritis (JIA): an update with particular emphasis on MRI.  Acta Radiol. 2013;54:1015–23. 8. Dimitriou C, Boitsios G, Badot V, Lê PQ, Goffin L, Simoni P.  Imaging of juvenile idiopathic arthritis. Radiol Clin N Am. 2017;55:1071–83. 9. Hemke R, Maas M, van Veenendaal M, Dolman KM, van Rossum MA, van den Berg JM, et  al. Contrast-enhanced MRI compared with the physical examination in the evaluation of disease activity in juvenile idiopathic arthritis. Eur Radiol. 2014;24:327–34. 10. Johnson K. Imaging of juvenile idiopathic arthritis. Pediatr Radiol. 2006;36:743–58. 11. Jordan A, McDonagh JE. Juvenile idiopathic arthritis: the paediatric perspective. Pediatr Radiol. 2006;36:734–42.

12. Karmazyn B, Bowyer SL, Schmidt KM, Ballinger SH, Buckwalter K, Beam TT, et  al. US findings of metacarpophalangeal joints in children with idiopathic juvenile arthritis. Pediatr Radiol. 2007;37:475–82. 13. Lanni S, Martini A, Malattia C. Heading toward a modern imaging approach in juvenile idiopathic arthritis. Curr Rheumatol Rep. 2014. https://doi.org/10.1007/s11926-014-0416-9. 14. MacKenzie JD, Vasanawala SS. Advances in pediatric MR imaging. Magn Reson Imaging Clin N Am. 2008;16:385–402. 15. Magni-Manzoni S, Malattia C, Lanni S, Ravelli A. Advances and challenges in imaging in juvenile idiopathic arthritis. Nat Rev Rheumatol. 2012;8:329–36. 16. Malattia C, Tzaribachev N, van den Berg JM, Magni-Manzoni S. Juvenile idiopathic arthritis – the role of imaging from a rheumatologist's perspective. Pediatr Radiol. 2018;48:785–91. 17. Miller E, Uleryk E, Doria AS. Evidence-based outcomes of studies addressing diagnostic accuracy of MRI of juvenile idiopathic arthritis. AJR Am J Roentgenol. 2009;192:1209–18. 18. Navallas M, Inarejos EJ, Iglesias E, Cho Lee GY, Rodríguez N, Antón J.  MR imaging of the temporomandibular joint in juvenile idiopathic arthritis: technique and findings. Radiographics. 2017;37:595–612. 19. Navallas M, Rebollo Polo M, Riaza L, Muchart López J, Maristany T.  Artritis idiopática juvenil, peculiaridades de la imagen en la edad pediátrica con especial interés en la resonancia magnética. Radiologia. 2013;55:373–84. 20. Nguyen JC, Lee KS, Thapa MM, Rosas HG. US evaluation of juvenile idiopathic arthritis and osteoarticular infection. Radiographics. 2017;37:1181–201. 21. Nusman CM, Hemke R, Benninga MA, Schonenberg-Meinema D, Kindermann A, van Rossum MA, et al. Contrast-enhanced MRI of the knee in children unaffected by clinical arthritis compared to clinically active juvenile idiopathic arthritis patients. Eur Radiol. 2016;26:1141–8. 22. Ording Muller LS, Humphries P, Rosendahl K. The joints in juvenile idiopathic arthritis. Insights Imaging. 2015;6:275–84. 23. Petty RE, Southwood TR, Manners P, Baum J, Glass DN, Goldenberg J, et  al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. J Rheumatol. 2004;31:390–2. 24. Pruthi S, Thapa MM. Infectious and inflammatory disorders. Magn Reson Imaging Clin N Am. 2009;17:423–38. 25. Shanmugavel C, Sodhi KS, Sandhu MS, Sidhu R, Singh S, Katariya S, et al. Role of power Doppler sonography in evaluation of therapeutic response of the knee in juvenile rheumatoid arthritis. Rheumatol Int. 2008;28:573–8. 26. Sheybani EF, Khanna G, White AJ, Demertzis JL. Imaging of juvenile idiopathic arthritis: a multimodality approach. Radiographics. 2013;33:1253–73. 27. Southwood T. Juvenile idiopathic arthritis: clinically relevant imaging in diagnosis and monitoring. Pediatr Radiol. 2008;38(Suppl 3):S395–402. 28. Sudoł-Szopińska I, Grochowska E, Gietka P, Płaza M, Pracoń G, Saied F, et al. Imaging of juvenile idiopathic arthritis. Part II: ultrasonography and MRI. J Ultrason. 2016;16:237–51. 29. Tattersall R, Rangaraj S.  Diagnosing juvenile idiopathic arthritis. Paediatr Child Health. 2007;18:85–9. 3 0. Workie DW, Graham TB, Laor T, Rajagopal A, O’Brien KJ, Bommer WA, et  al. Quantitative MR characterization of disease activity in the knee in children with juvenile idiopathic arthritis: a longitudinal pilot study. Pediatr Radiol. 2007;37:535–43.

4

Imaging of Juvenile Spondyloarthritis and Pediatric Collagen Vascular Disorders

4.1

Introduction

Juvenile spondyloarthritis (also called juvenile spondyloarthropathies) comprises a heterogeneous group of conditions characterized by inflammation of the sacroiliac joints and of the spine, varied degrees of enthesitis and arthritis, association with HLA-B27 antigen, and disease onset before age 16, accounting for 15–20% of all forms of arthritis in skeletally immature patients. Even though classification of juvenile spondyloarthritis is a controversial issue (which is beyond the scope of this chapter), this group of diseases classically encompasses juvenile ankylosing spondylitis, juvenile psoriatic arthritis, reactive arthritis, arthritis associated with inflammatory bowel disease, and the undifferentiated forms of spondyloarthritis. In addition to the axial skeleton, juvenile spondyloarthritis also affects the peripheral joints, mostly in the lower extremities, and prominent enthesopathy is often present. Peripheral arthritis and enthesitis of the lower extremities usually preponderate during the initial stage, and sacroiliitis and/or spondylitis are late findings, so that children with early-stage juvenile spondyloarthritis may be incorrectly diagnosed as having classic juvenile idiopathic arthritis. Radiographic criteria employed for adult-type disease are fairly insensitive for early diagnosis of juvenile spondyloarthritis, and, therefore, more sensitive imaging methods such as ultrasonography (US) and magnetic resonance imaging (MRI) have become increasingly important in this setting, given that early diagnosis and timely introduction of treatment are paramount for improved outcome and better quality of life. Pediatric collagen vascular disorders, on their turn, are multisystemic autoimmune diseases of uncertain etiology that are similar in many ways to their adult counterparts. Nonetheless, peculiarities in the presentation and evolution of the juvenile forms of collagen diseases make them unique, thus deserving separate study. Even though osteoarticular manifestations are not the more relevant in most patients, some imaging findings are quite typical, and it is important for the radiologist to be acquainted with them.

4.2

Juvenile Spondyloarthritis

Before proceeding to the study of juvenile spondyloarthritis, it would be wise to add a cautionary note about MRI and the immature sacroiliac joints. First of all, there are peculiar issues related to age-dependent developmental changes of the sacrum: this bone develops from segmental and lateral apophyses that become progressively ossified from age 9 to 17. In the immature skeleton, these cartilages appear relatively hyperintense compared with the adjacent bone and should not be misconstrued as bone marrow edema on fluid-­sensitive sequences (Fig. 4.1). As the pediatric sacroiliac joint is a complex and challenging structure on imaging studies, it requires from the radiologist a thorough comprehension of its anatomy and development. In addition, MRI will likely play an even more important role in this setting in the near future, as very recent data suggest that active sacroiliitis in juvenile spondyloarthritis is probably more frequent and occurs earlier than previously thought and is frequently asymptomatic. However, even though MRI is considered the gold standard for the diagnosis of sacroiliitis, there is a lack of reporting standards or diagnostic criteria for pediatric sacroiliac MRI, and most radiologists adapt adult scoring systems not yet validated in children. There are gaps in the literature that must be filled in order to improve the quality of evidence, so that building up experience in this topic is still needed.

4.2.1 Juvenile Ankylosing Spondylitis Juvenile ankylosing spondylitis (JAS) is more frequent in males, and disease onset usually occurs between the end of childhood and the first years of adolescence. Arthritis and enthesitis (inflammation involving the sites of insertion of tendons, ligaments, and joint capsules) are the more important articular manifestations in JAS.  In contradistinction to the adult form of ankylosing spondylitis, in which axial involvement predominates from the start, in JAS years (or even decades, if at all) may elapse before spondylitis and sacroiliitis become evident.

© Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_4

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Fig. 4.1  Coronal STIR images of a 9-year-old female showing normal appearance of the sacrum and sacroiliac joints. The segmental and the lateral apophyses of the sacral wings appear as hyperintense transverse

and marginal longitudinal bands, respectively, which are symmetric and uniform in thickness along both joints and should not be confused with bone marrow edema

Arthritis is more common in large joints of the lower extremities – such as the hip, knee, ankle, and first toe – and the peripheral joints are involved less often; arthritis in the joints of the upper limbs is only sporadic. If compared to that found in adulttype ankylosing spondylitis, articular disease in JAS usually follows a more severe course, with unrelenting arthritis, disability, and occasional need for joint replacement (Figs. 4.2 and 4.3). Radiographic findings related to peripheral arthritis include progressive joint space narrowing and bone erosions of late appearance (Fig. 4.2). MRI is the imaging method of choice for early diagnosis, demonstrating joint effusion, synovial thickening, and inflammation of the soft tissues and of the bones, even in the pre-erosive stage, as well as cartilaginous and bone erosions in advanced disease (Fig. 4.2). US is also able to demonstrate joint effusion, synovitis, and soft-tissue swelling as soon as they appear, being also capable to depict cartilaginous damage and bone erosions (although inferior to MRI for this purpose). Enthesitis is more frequently found in the insertions of the extensor mechanism of the knee and in the calcaneal entheses. Related findings on imaging studies include bone marrow edema, periosteal reaction, edema of the adjacent soft tissues, bone spurs, and enthesophytes, as well as soft-tissue swelling and fluid distention of adjacent bursae (Fig.  4.2). Periostitis is more common in the hands, while enthesophytes are more frequently seen in the tarsal bones (Fig. 4.2). The affected tendon appears thickened and heterogeneous on US and MRI (Fig.  4.2), showing increased perfusion on Doppler US and post-gadolinium enhancement.

Sacroiliitis in JAS is prototypical, very similar to that found in adult-type disease. Unlike in adults, however, axial arthritis is not required for diagnosis of juvenile spondyloarthritis, and many children with JAS will never develop axial disease. When positive, radiographs show loss of definition of the articular surfaces, bone erosions, and subchondral sclerosis in the sacroiliac joints, which are most often bilateral, although unilateral disease may be seen at presentation. As the disease advances, there is gradual narrowing of the joint spaces, and ankylosis may be found in late-stage JAS (Fig.  4.3), the latter being quite rare in children. Pseudo-­ widening of the joint space is a peculiar finding related to confluence of subchondral erosions (Figs.  4.3 and 4.4). Radiographs, however, are insensitive for the assessment of sacroiliac joints, largely because of their complex anatomy; furthermore, classic radiographic findings are only found in advanced sacroiliitis (Fig. 4.3), and this imaging method is unable to distinguish active from inactive disease. In the current stage of knowledge, considering the very limited utility of radiographs for early detection of sacroiliitis, routinely requiring radiographs prior to MRI in screening is ­considered by some authors as an obsolete and useless practice that may lead to delayed diagnosis and introduction of therapy. MRI is the most suitable study for sacroiliac evaluation as it is able to disclose both signs of disease activity and chronic (structural) manifestations of sacroiliitis; therefore, the evidence is that MRI should replace radiography as the first line of investigation. Active lesions of sacroiliitis include osteitis,

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Fig. 4.2  An 18-year-old male with JAS and arthritis of the left midfoot and hindfoot since age 15. Lateral view (a) of the ankle demonstrates dorsal enthesophytosis and diffuse joint space narrowing in the midfoot, as well as and subcortical lucencies in the lowermost portion of the cuboid bone. In (b), sagittal T1-WI (upper row) and fat sat PD-WI (lower row) of the same ankle reveal arthritic changes, with joint effusion, cartilaginous thinning, synovial thickening, and bone marrow edema, as well as erosions in the talus, in the calcaneus, and in the cuboid. Post-gadolinium images (c) disclose enhancement of the thick-

ened synovium and within bone erosions. Tarsitis is a peculiar manifestation of juvenile spondyloarthritis, representing a combination of inflammation and bone proliferation that often leads to ankylosis. In (d), coronal T1-WI (left) and fat sat T2-WI (right) of the left shoulder of a 17-year-old male with JAS disclose joint effusion and synovial thickening, more evident in the axillary recess, as well as enthesopathy of the rotator cuff, with erosion and bone marrow edema adjoining the insertion site of the supraspinatus tendon, which displays mildly heterogeneous signal intensity

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Fig. 4.2 (continued)

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synovitis, retro-articular enthesitis, and capsulitis. Areas of subchondral marrow edema (osteitis) show post-gadolinium enhancement and are present since the very early stages of sacroiliitis, way before the appearance of erosions (Fig. 4.5). If compared to adult sacroiliitis, areas of subchondral bone

Fig. 4.3  Pelvic radiograph of a 27-year-old patient with JAS since late adolescence. There is severe osteoarthritis of the left hip (secondary to chronic arthritis) and right-sided sacroiliitis with pseudo-widening of the joint space, as well as ankylosis of the left sacroiliac joint and of the lower lumbar spine. Total replacement of the right hip joint is also seen, with wide lucent zones surrounding both components of the prosthesis, indicative of loosening

Fig. 4.4  A 12-year-old male with JAS. Coronal CT image shows confluent subchondral erosions in the iliac surface of the left sacroiliac joint, with subtle sclerosis of the adjacent bone. This confluence leads to pseudo-widening of the sacroiliac joint space, similar to that seen in the right sacroiliac joint of the patient of Fig. 4.3

a

Fig. 4.5  Coronal STIR image (a) and post-gadolinium fat sat T1-WI (b) of a 13-year-old child with JAS and pre-erosive sacroiliitis. There is asymmetric subchondral bone marrow edema along the sacral surface and in the lowermost portion of the iliac surface of the right sacroiliac

joint, with post-contrast enhancement. Joint spaces are preserved and erosions are absent. Similar (and more prominent) findings are seen in (c) in a 9-year-old male with axial spondyloarthritis and bilateral sacroiliitis (upper row, T1-WI; lower row, fat sat T2-WI)

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Fig. 4.5 (continued)

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Fig. 4.5 (continued)

marrow in children have been described as smaller and less pronounced, although the specificity of this finding is much higher in pediatric patients than in adults. Evidence of synovitis includes increased signal intensity on T2-WI and post-­ gadolinium enhancement inside the articular space in inflamed sacroiliac joints, mainly the latter. Retro-articular enthesitis appears on MRI as high signal intensity and/or enhancement of the posterior ligaments, while capsulitis is seen as high signal intensity on fluid-sensitive sequences and/or abnormal enhancement involving the capsule of the sacroiliac joint, both (retro-articular enthesitis and capsulitis) highly specific for sacroiliitis. On their turn, structural abnormalities include erosions, sclerosis, fat infiltration, and ankylosis, all of them considered of high specificity for pediatric sacroiliitis. Bone erosions are usually small, and large subchondral cysts are relatively rare (Fig. 4.6); in children, erosions often are not depicted as easily as in adults on T1-WI because the osteochondral interface is hazy due to incomplete skeletal maturation, and some authors advocate STIR or fat sat T2-WI as more appropriate for their detection. Subchondral sclerosis appears as areas of low signal intensity in all sequences (Fig. 4.6). Fatty replacement of the bone marrow is a late finding, indicative of past episodes of inflammation and subsequent healing and typically found in chronic sacroiliitis (Fig.  4.6). Whole-body MRI has been recently described as a potentially useful tool for early detection of juvenile spondyloarthritis and to monitor disease activity and therapy efficacy. However, as stated in the introduction of this topic, MRI assessment of sacroiliitis features

in children is not overall as studied as in adults, and some issues are yet to be elucidated. For example, recent data suggest that there is only limited added diagnostic value for contrast administration in MRI of the sacroiliac joints in juvenile spondyloarthritis because “standard” sequences would be sufficient to detect both acute and chronic inflammatory changes. Other authors, on the other hand, have found that synovial enhancement would be the most sensitive among all MRI findings in these patients and might be detected even without accompanying bone marrow edema; furthermore, variations in the intensity and extent of synovial enhancement would mirror the efficacy of the treatment on serial studies (Fig. 4.6). Currently, there seems to be a trend among pediatric rheumatologists toward non-enhanced MRI for the assessment of pediatric sacroiliitis, even though this issue is still a matter of debate. In spite of the excellent bone assessment provided by computed tomography (CT) (Fig. 4.4), this imaging modality is unable to yield any information about inflammation activity, and it is exceptionally used nowadays for sacroiliac evaluation in juvenile spondyloarthritis. Likewise, notwithstanding the high sensitivity of bone scintigraphy, its usefulness is very limited in the assessment of sacroiliitis in juvenile spondyloarthritis, mostly because of technical issues in the evaluation of the immature sacroiliac joints (see Chap. 1) and its inherently low specificity and spatial resolution (Fig. 4.7). Sacroiliitis almost always precedes vertebral involvement in JAS. Spondylitis usually appears in late-stage disease and is rarely found in children, affecting most often the thoraco-

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a

b

Fig. 4.6  MRI of the sacroiliac joints of two different patients. In (a), in a 19-year-old male with JAS since age 15, there is bilateral subchondral osteitis, which appears as areas of low signal intensity on T1-WI (left image) and high signal intensity on STIR (right image), as well as narrowing of the joint spaces and irregularity of the articular surfaces due to micro-erosions; a dominant bone erosion is seen in the upper half of the left sacral surface. Fatty replacement of the medullary bone is also

present, mostly in the left sacral wing. In (b), MRI of a 14-year-old male with JAS and good clinical control shows narrowing of the left sacroiliac joint space and subchondral sclerosis, which appears as hypointense areas on transverse T2-WI (left images) and coronal post-­ gadolinium fat sat T1-WI (right image). The absence of bone marrow edema or abnormal post-contrast enhancement is indicative of inactive disease

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Fig. 4.7  Bone scintigraphy of the same patient as in Fig. 4.4, posterior view. There is increased uptake in the lowermost portion of the left sacroiliac joint, indicative of active inflammation. Radiographs and CT are insensitive for assessment of disease activity

lumbar spine of adults with long-standing JAS. Involvement of the cervical spine is rare and late, presenting a more benign course if compared to that seen in juvenile idiopathic arthritis. Classic radiographic findings (infrequently seen in skeletally immature patients) include sclerosis of vertebral corners, squaring of the vertebral bodies, syndesmophytosis, and ankylosis of the facet joints (Fig. 4.3).

4.2.2 Juvenile Psoriatic Arthritis Juvenile psoriatic arthritis (JPA) is a form of seronegative arthritis associated with psoriasis, much less common than the adult form of the disease. JPA is defined as persistent arthritis (more than 6 weeks) with onset prior to age 16 and either the presence of a psoriatic rash or, in the absence of rash, at least 2 of the following minor criteria: first-degree relative with psoriasis, nail pitting or onycholysis, and ­dactylitis. Even though radiographic findings of psoriatic arthritis are similar in adults and children, one must keep in mind that inflammatory involvement of the sacroiliac joints and spine is less frequent in pediatric patients and full radiographic evidence of psoriatic arthritis is rarely found in children. Peripheral arthritis is usually oligoarticular and asymmetric, affecting most often the knees and the small joints of the hands and feet.

Fig. 4.8  A 12-year-old female with severe JPA. Erosive arthritis can be seen in the interphalangeal joints of the third finger, mainly distal. Solid periosteal reaction along the diaphyses of the proximal phalanges is also present, from the second to the fourth digits. Extensive carpal and carpometacarpal ankylosis is evident

While the association of periostitis, bone erosions, proliferative bone changes, and enthesitis is very characteristic of JPA, radiographs are insensitive for early-stage JPA, as these are late findings. The hands are affected more often and more severely than the feet, and arthritis of the distal interphalangeal joints is typical (Fig. 4.8); osteolysis and ankylosis are occasionally observed concomitantly in the same hand or foot (Fig. 4.8). Association of peripheral erosions and periostitis may lead to the classic “mouse ears” appearance (Fig. 4.9). Arthritis mutilans is a rare and severe form of JPA, presenting imaging findings similar to those of juvenile idiopathic arthritis (Figs. 4.10 and 4.11). Abnormalities commonly found in the adult-type form of the disease, such as acro-osteolysis (resorption of the distal phalanges), whiskering (proliferative bone neoformation in the entheses), and periostitis, tend to be less aggressive in JPA.  Nevertheless, enthesopathic lesions may be the only radiographic change for a long time, appear-

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Fig. 4.9  Radiograph of the feet of a child with JPA (magnification of the right forefoot in the right image). Erosive arthritis is seen in the interphalangeal joint of the right hallux (“mouse ears” appearance), as well as ankylosis of the corresponding metatarsophalangeal joint. Arthritis of the metatarsophalangeal joint of the ipsilateral fourth toe is also evident,

with the classic “pencil-in-cup” configuration characterized by bone remodeling and a saucer-like appearance of the joint surface of the proximal phalanx, in which the severely eroded metatarsal head articulates. Periostitis is seen along the proximal phalanx of the fifth toe on the right and along the diaphysis of the fourth metatarsal bone

Fig. 4.10  Bilateral hip arthritis in a preadolescent girl with JPA, more important in the left hip, in which there is narrowing of the joint space and erosions of the articular surfaces

ing as areas of ossification and erosions in the bony component of the entheses (Fig. 4.12). The so-called pencil-­in-­cup deformity, a classic finding of psoriatic arthritis in adults, is uncommonly seen in children (Figs. 4.9 and 4.13). Anterior chest wall inflammation is not uncommon in spondyloarthritis, mostly found in psoriatic arthritis, involving the sternoclavicular, manubriosternal, and sternocostal joints and affecting as much as one-fourth of the patients (both children and adults) with the axial form of the disease (Fig. 4.14). The so-called sausage finger (dactylitis) results from a combination of soft-

Fig. 4.11  Deforming arthritis of the right elbow of a child with psoriasis. There is marked remodeling of the joint surfaces, with widening of the trochlear notch. Bone erosions are present in the distal humerus

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Fig. 4.12  Reformatted sagittal CT images of the right foot (a and b) of a 10-year-old female with JPA and tarsitis showing bone erosions, subchondral sclerosis, bone proliferation, and enthesophyte formation at the site of attachment of the dorsal talonavicular ligament in the dorsal surface of the navicular bone, as well as densification of the adjacent subcutaneous tissue and diffuse osteoporosis. After successful therapy,

reformatted sagittal CT images of the same foot obtained 1 year later (c, upper row) disclose complete bone healing and restoration of normal bone density, with residual deformity and mild sclerosis of the dorsal portion of the navicular; there is complete absence of edematous changes on sagittal fat sat T2-WI and T1-WI (lower row) performed on the same day

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Fig. 4.13  Bilateral erosive arthritis of the metatar­ sophalangeal joints can be seen in the feet of this female patient with JPA, more important in the right foot. Note the typical “pencil-in-­ cup” deformity and lateral deviation of the toes, as well as marked osteoporosis

tissue inflammation, tenosynovitis, arthritis, and periostitis, which is very suggestive of JPA – especially when found in a toe – even in the absence of dermatologic changes. If compared to JAS, there is more extensive involvement of the small joints and less enthesopathy in JPA, features that help to narrow the differential diagnosis. Sacroiliitis (most often asymmetric) and spondylitis are also late findings. Acute inflammatory changes are well demonstrated with MRI, with osteitis (usually on both sides of the joint), synovitis, capsulitis, and enthesitis associated with post-gadolinium enhancement (Fig. 4.15) that are present long before the appearance of structural bone changes. Such structural changes include bone erosions, fatty replacement of the bone marrow, subchondral sclerosis, and ankylosis (Figs. 4.16, 4.17, and 4.18). Contrast-enhanced MRI is the most useful imaging method for assessing the extent of the disease and the activity of the inflammation in early-­stage JPA, as well as to monitor disease evolution (Fig. 4.19).

4.2.3 A  rthritis Associated with Inflammatory Bowel Disease in Children Arthritis is found in approximately 10% of the children with inflammatory bowel disease, and it may either precede or follow the clinical onset of the subjacent enteropathy. Two distinct types of articular disease may occur, one of them with predominance of peripheral arthritis, without sex predilection, and another one with predominance of spondylitis and sacroiliitis, more common in males. Asymmetric nondestructive oligoarticular arthritis is the most common pattern, whose activity parallels that of the intestinal disease. Knees, ankles, and wrists are affected most often, followed by hands and shoulders. Axial involvement is less common, indistinguishable from that found in JAS (see Sect. 4.2.1), and both sacroiliitis and spondylitis may progress regardless of the control of the intestinal disease; nevertheless, sacroiliitis and spondylitis are rarely found in children and usually appear in adult age. Enthesitis, osteoporosis, periostitis, and digital clubbing may also be present.

4.2 Juvenile Spondyloarthritis Fig. 4.14  Arthritis of the manubriosternal joint in a 13-year-old female with JPA and 2 years of disease evolution. Reformatted coronal (a) and sagittal (b) CT images of the sternum disclose bone erosions and subchondral sclerosis in the articular surface of the body of the sternum for the manubrium, typical of chronic arthritis

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Fig. 4.15  A 20-year-old male with long-standing peripheral JPA and unsuspected sacroiliac involvement. In (a), coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) reveal unilateral right sacroiliitis characterized by extensive subchondral bone marrow edema (osteitis) both in the iliac and sacral joint surfaces and associated synovitis, with post-contrast enhancement within the joint space and in the inflamed bone. There is also evidence of capsulitis, with thickening,

increased signal intensity, and contrast enhancement of the ipsilateral joint capsule (arrows), as well as subchondral sclerosis in the upper portion of the iliac surface. In addition to the above described findings, axial fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) in (b) disclose right-sided edematous changes of the posterior ligaments and subtle post-contrast enhancement (arrows) corresponding to active enthesitis

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Fig. 4.16  A 12-year-old female with polyarticular JPA and arthritis of the right hip. In (a), anteroposterior radiograph of the pelvis shows narrowing of the joint space of the right hip, with sclerosis of the subchondral bone of the acetabular roof. In (b), coronal T1-WI (left), fat sat

T2-WI (center), and post-gadolinium fat sat T1-WI (right) reveal thinning of the articular cartilages, subchondral sclerosis, and osteitis in the acetabular roof and post-contrast enhancement of the bone marrow edema. There is diffusion of the injected gadolinium to the joint cavity

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Fig. 4.17  Coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) of a patient with axial JPA showing bilateral sacroiliitis – more prominent on the right – with post-contrast enhancement of the inflamed bone marrow and synovium. There is a clear-cut erosion in the

a

sacral articular surface of the left sacroiliac joint (arrow), more conspicuous on fat sat T2-WI and containing enhancing synovial tissue. Pseudo-­widening of the joint spaces is present, related to confluent micro-­erosions along the iliac surfaces of both joints

b

Fig. 4.18  Ankylosing tarsitis of the left foot in a girl with severe, progressive, and unrelenting polyarticular JPA.  Lateral radiograph (a) reveals extensive ankylosis of the bones of the hindfoot and midfoot and severe erosive arthritis of the tibiotalar joint. T1-WI (left) and fat

sat T2-WI (right) in the coronal (b) and axial (c) planes show active arthritis in the tibiotalar joint and demonstrate the ankylosis of the tarsal bones

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Fig. 4.18 (continued)

Fig. 4.19  Coronal STIR images of the sacroiliac joints of a male adolescent with axial JPA and bilateral sacroiliitis obtained at ages 15 (left) and 17 (right) disclosing changes in the pattern of joint involvement over time. In the first image, the right ilium exhibits extensive osteitis, which completely subsided 2 years later. Nonetheless, even though the

sacral erosions are less well defined in the second image, bone marrow edema along the sacral surfaces – which was previously quite circumscribed – has a more diffuse appearance, mostly in the left side. Osteitis is also more prominent than before in the iliac side of the left sacroiliac joint

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4.2.4 Reactive Arthritis

a

Reactive arthritis usually occurs following an intestinal infection (mainly caused by Yersinia, Shigella, Salmonella, or Campylobacter) or an infection of the urogenital tract (most frequently caused by Chlamydia). Nonetheless, this is not a form of septic arthritis, as there are no viable microorganisms in the synovial fluid aspirated from affected joints. The classic clinical triad – arthritis, urethritis, and conjunctivitis – is only found in a minority of the patients. The disease usually affects males between 15 and 35  years of age, being rarely found in younger individuals. Arthritis is most often monoarticular and/or oligoarticular and asymmetric, characteristically affecting the joints of the lower limbs (Fig. 4.20); involvement of the first interphalangeal joint is typical, and dactylitis similar to that of JPA may be found. Tenosynovitis and synovial cysts may also be present. It is most commonly a self-limited condition, and erosive arthropathy is only occasionally found (Fig. 4.20). Sacroiliitis (usually symmetric and bilateral) and enthesitis (inflammation of the calcaneal entheses is a classic manifestation) may be present, but are less common in skeletally immature patients than in adults (Figs. 4.20, 4.21, and 4.22). Radiographs are most often normal or non-specific in benign cases (Fig. 4.23). Fig. 4.20  Reactive arthritis with 6 months of evolution in a 15-yearold male adolescent. Radiograph of the left foot (a) discloses a subchondral lucency in the proximal phalanx of the third toe and faint periosteal reaction along this bone. US of the third metatarsophalangeal joint (b) shows heterogeneous joint effusion and marked synovial thickening (upper row); in spite of the prominent synovial proliferation, Doppler US shows only mild hyperemia (lower row). T1-WI (c, left) reveals joint effusion, circumferential bone erosions in the head of the third metatarsal, and synovitis, with bone marrow edema in the adjacent joint surfaces on fat sat T2-WI (c, right) and intense enhancement of the inflamed tissues on post-­gadolinium fat sat T1-WI (d). In addition to arthritis of the third metatarsophalangeal joint, bone scintigraphy (e) also discloses increased uptake on both sacroiliac joints, indicative of active sacroiliitis

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Fig. 4.20 (continued)

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e

Fig. 4.20 (continued)

Plantar

Retificada

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Fig. 4.21  A 19-year-old male with reactive arthritis since adolescence. Pelvic radiograph (a) shows bilateral sacroiliitis with subchondral erosions and sclerosis. Lateral view of the left calcaneus (b) discloses

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signs of enthesopathy at the insertion of the Achilles tendon, with cortical irregularity, erosions, and bone neoformation

a

Fig. 4.22  A 14-year-old patient with reactive arthritis. In (a), fat sat PD-WI of the left knee in the coronal (left) and sagittal (right) planes show enthesopathy at the insertion of the quadriceps tendon (which is thickened and heterogeneous) and at the origin of the medial collateral ligament, with edema of the adjacent bone marrow and soft tissues.

Mild synovitis is also present, and enlarged lymph nodes can be seen in the popliteal fossa. Bilateral sacroiliitis is evident on a transverse STIR image (b, upper image), more extensive in the right side, with post-­ gadolinium enhancement on fat sat T1-WI (b, lower image)

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b

Fig. 4.22 (continued)

4.3

Pediatric Collagen Vascular Disorders

4.3.1 Juvenile Dermatomyositis

Fig. 4.23  A 12-year-old child with reactive arthritis in the left ankle and knee. Radiograph of the affected ankle shows only soft-tissue swelling, without further findings

Despite its rarity, juvenile dermatomyositis (JDM) is the most common of the noninfectious inflammatory myopathies of childhood, affecting mainly school-aged females around 6–7 years of age. Patients with JDM present proximal and symmetric muscle weakness and high serum levels of muscle enzymes; unlike adult-onset dermatomyositis, JDM is not associated with increased incidence of malignancies, and prognosis is overall good. Articular symptoms occur in approximately half of the patients in early-stage disease, mostly arthralgia and joint stiffness. Arthritis is typically transient, nonerosive, and non-­ deforming, characterized by oligoarthritis in twothirds of the affected patients and polyarthritis in the remaining; knees, wrists, elbows, and fingers are the most frequently involved joints, and marked osteoporosis may be present (Fig. 4.24). Dystrophic calcinosis is a characteristic feature of chronic JDM, occurring predominantly in superficial locations (mostly the elbows and knees). The calcific deposits are rarely present at onset, developing later during the course of the disease as superficial skin nodules, deeply seated deposits, calcified plaques along fascial planes or in a widespread “exoskeleton” pattern (Figs. 4.24, 4.25, 4.26, 4.27, and 4.28), appearing on MRI as areas of low signal intensity. Calcifications may be seen

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Fig. 4.24  Arthritis of the hands and wrists in a child with JDM. In spite of subtle subluxation of the metacarpophalangeal joints of the thumbs, more evident in the right hand, there are no signs of erosive disease. Soft-tissue swelling and generalized osteoporosis are also present, as well as symmetric and bilateral calcifications in the soft tissues of the distal forearms

on US as hyperechogenic areas even before they become apparent on radiographs (Fig. 4.29). With regard to myositis, radiographs are non-specific and fairly insensitive for assessment of the acute phase. In long-­ standing JDM, radiographic findings include muscle atrophy, muscular calcifications (Figs. 4.25, 4.27, and 4.28), and flexion deformities. US findings in the acute phase of myositis include increased volume and decreased echogenicity of the affected muscles, while there is increased echogenicity, fatty infiltration, and atrophy in late-stage JDM; fibrosis and/or calcifications appear as hyperechogenic foci with posterior acoustic shadowing in the muscles and in the subcutaneous tissue (Fig. 4.29). CT is not useful for the assessment of active myositis, but it is the best imaging modality available to depict soft-tissue calcifications (Fig.  4.30). MRI is the preferred method to confirm the diagnosis in this setting by revealing edematous changes related to active inflammation during the acute stage (myositis, tenosynovitis, fasciitis, cellulitis) and to demonstrate the distribution of the disease. There is often a symmetric pattern of muscle edema

c­ haracterized by increased signal on fluid-sensitive sequences involving most commonly the adductor muscles and the muscles of the proximal thigh (Fig. 4.31). Furthermore, MRI is a useful tool to monitor disease evolution and treatment response, as abnormally increased T2 signal resolves with successful therapy. Atrophy and fatty replacement of the affected muscles related to long-standing JDM are also evident on MRI, as well as foci of fibrosis and/or calcification, which appear hypointense in all sequences (Fig.  4.31). However, MRI is limited for the detection of calcifications, and even large plaques that would be easily seen on radiographs can be missed. Both US and MRI may be used to select suitable sites of active myositis for muscle biopsy; MRI is more sensitive, but US is less costly and more convenient in children, with no need for sedation. Whole-body MRI has been described as a promising tool for global assessment of inflammation and monitoring of the disease course in JDM; inflammatory changes within muscles, fascia, and the subcutaneous tissue seem to correlate with disease activity and might be useful to tailor treatment and assess its efficacy.

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b

Fig. 4.25  A 3-year-old child with JDM. Radiographs show extensive and confluent plaques of calcification in the soft tissues of the upper limbs (a) and lower limbs (b), predominantly located in the elbows and in the proximal portions of the thighs and arms

4.3.2 Juvenile Systemic Lupus Erythematosus

Fig. 4.26  Chest X-ray of an adolescent with long-standing JDM. There are multiple calcifications in the soft tissues of the chest wall and of the arms

The juvenile form of systemic lupus erythematosus (JSLE) is the most common of the juvenile collagen vascular diseases. It is characterized by onset before 16  years of age, and approximately 20% of all lupus patients are diagnosed before skeletal maturation, mostly females around age 12, which tend to present a more severe clinical course than adults with the disease. The majority of these juvenile patients will show some kind of musculoskeletal involvement, and arthralgia and/or arthritis are the most frequent manifestations. Affected children usually present bilateral and symmetric polyarthritis, which is often transient, commonly involving the knees, ankles, hands, and wrists and, less frequently, elbows; even though synovitis may be present (Figs. 4.32 and 4.33), erosive articular disease is rare. Other findings include periarticular osteoporosis, “swan neck” and “boutonniere” digital deformities (see Chap. 3), and a nonerosive deformity with ulnar deviation and subluxation of the metacarpophalangeal and, occasionally, proximal interphalangeal joints (Jaccoud

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Fig. 4.27  Bizarre calcinosis is seen on the radiographs of this adolescent with JDM, involving the soft tissues of the upper limbs (a), of the pelvis (b), and of the lower extremities (c). Diffuse osteoporosis is also evident

arthropathy, much less common than in the adult form of the disease). Tenosynovitis is relatively frequent (Fig. 4.33), but myositis is rarely found. US is usually the first line of investigation for the assessment of arthritis and tenosynovitis in JSLE (Fig. 4.33), but MRI is more precise in determining the

real extent of synovitis (Figs.  4.32, 4.33, 4.34, and 4.35), allowing early detection of erosions and osteochondral lesions (Figs. 4.34 and 4.35). One of the most feared complications of JSLE is avascular necrosis, which is more common in the femoral heads and tibial plateaus (Fig. 4.34).

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Fig. 4.28  Patterns of calcification in two distinct patients with JDM. In (a), lateral views of the left thigh of a 12-year-old female display large calcified masses and nodules of varied size and density in the posterior soft tissues of the lower limb, spanning the thigh, the popliteal region,

and the proximal leg; marked osteoporosis is also present. In (b), radiographs of the left forefoot of a 15-year-old female show a cluster of densely calcified nodular deposits with varied sizes and shapes in the soft tissues plantar to the first metatarsal bone

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d

Fig. 4.29  On US, calcifications in the left lower limb of a patient with JDM appear as hyperechogenic areas with posterior acoustic shadowing in the subcutaneous tissue (a–c), in the muscles, and along the fas-

cial planes (d). In this study, there are micronodular (a and b), nodular-clustered (c), and plaque-like (d) calcified deposits

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b

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d

Fig. 4.30  CT of the chest of a child with JDM. Images in the transverse plane with soft-tissue window settings (a–d) demonstrate several superficial calcifications in the chest wall

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b

Fig. 4.31  In (a), axial STIR images of the lower limbs of a 7-year-old boy with acute JDM disclose a symmetric pattern of muscle edema affecting mainly the gluteus maximus and the vastus lateralis muscles. In another patient, a 9-year old girl with JDM and active myositis, coronal fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) of the thighs (b and c) and of the left hip (d) reveal a symmetric pattern of muscle edema affecting predominantly the adductor muscles and the proximal thighs, with post-gadolinium enhancement. In (e), transverse

T2-WI of the pelvis of a 16-year-old female with chronic JDM shows striking atrophy and fatty replacement of the gluteal muscles, with hyperintense fat streaks permeating the muscle bellies. The anterior abdominal wall is markedly atrophic, with a strap-like appearance of the corresponding muscles. Symmetric and bilateral subcutaneous calcinosis is also present, mainly in the buttocks, appearing as hypointense streaks across the gluteal fat. (a is a courtesy of Dr. Bernardo Martins, MD, SARAH Brasília, Brasília, Brazil)

4.3 Pediatric Collagen Vascular Disorders

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d

e

Fig. 4.31 (continued)

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4.3.3 J uvenile Systemic Sclerosis and Juvenile Localized Scleroderma Scleroderma is a generic denomination applied to a group of connective tissue diseases characterized by excessive deposition of collagen, cutaneous fibrosis, and skin induration. There are two major subtypes, one of them characterized by cutaneous sclerosis and involvement of the internal organs,

called systemic sclerosis, and the other predominantly limited to skin involvement, called localized scleroderma (or morphea). In either of these subtypes, juvenile scleroderma is defined by onset before age 16, being rarer than the classic adult form. Juvenile systemic sclerosis (JSS) is very rare, being the less frequent among the juvenile variants of scleroderma, affecting mainly females between 10 and 16 years of age.

Fig. 4.32  A 14-year-old female with JSLE since age 8 complaining of right-sided shoulder pain. Coronal (upper row) and sagittal (lower row) fat sat PD-WI demonstrate subacromial bursitis, with no evidence of erosive arthropathy

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Fig. 4.33  A 15-year-old female with JSLE. In (a), Doppler US of the second metacarpophalangeal joint of the right hand reveals joint effusion, synovial thickening, and increased blood flow. In (b), the extensor tendons at the level of the ipsilateral wrist are surrounded by heterogeneous, hypoechogenic material, corresponding to fluid and thickened synovium. Coronal STIR image (c, left) and post-gadolinium fat sat T1-WI (c, right) reveal nonerosive arthritis of the proximal interphalangeal joints and, more importantly, of the metacarpophalangeal joints,

much more evident on post-contrast T1-WI due to the enhancement of the inflamed synovium. In (d), in addition to metacarpophalangeal arthritis, transverse STIR images (left) and post-gadolinium fat sat T1-WI (right) also disclose flexor and extensor tenosynovitis. Fluid distension of the flexor tendon sheaths is quite evident, as well as ruptures of the radial sagittal bands of the extensor mechanisms from the second to the fourth digits, with ulnar subluxation of the central extensor tendons

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d

Fig. 4.33 (continued)

Fig. 4.34  Transverse post-gadolinium fat sat T1-WI of the left knee of an adolescent with JSLE displaying diffuse enhancement of the thickened synovium and erosions in the patellar cartilage. This patient had several areas of avascular necrosis in the proximal tibia and in the distal femur, the latter partially seen in this image as a geographic lesion in the medullary bone, displaying abnormal enhancement

Manifestations involving the musculoskeletal system and the skin are early and common. Arthritis (which is an early finding in JSS) and myositis are more prevalent than in adult-­type disease. On the other hand, localized juvenile scleroderma (LJS) is ten times more frequent than JSS, more common in females, with disease onset usually occurring around age 7. The clinical spectrum of LJS varies from small plaques of cutaneous sclerosis to extensive dermatofibrosis, but the most common form is linear scleroderma, characterized by one or more band-like areas of skin induration that usually occur asymmetrically in one of the limbs. When the face is involved, lesions are typical, varying from scleroderma “en coup de sabre” (asymmetric band-like lesion affecting the scalp and the supraorbital region  – Fig. 4.36) to Parry-Romberg syndrome (a more diffuse condition in which there is progressive facial atrophy, affecting mostly the skin and the subcutaneous tissue  – Fig.  4.37). High-frequency US reveal dermal thickening and hypodermal thinning, and active lesions demonstrate increased hypodermal echogenicity and increased Doppler flow; changes in lesion vascularity and tissue thickness over time provides useful insight on efficacy of disease treatment. US may also show calcifications, sclerosis, and atrophy in the

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Fig. 4.35  Coronal STIR images of both knees of a 15-year-old female patient with JSLE and lupus arthropathy demonstrating erosions in the joint surfaces of the lateral femoral condyles, surrounded by bone marrow edema and associated with small joint effusions

affected soft tissues. MRI is more accurate in demonstrating the real extent of the lesions and to monitor disease activity: if active inflammation is present, the dermis appears thickened, with edema of the subcutaneous tissue and post-gadolinium enhancement, while chronic lesions show skin and fat atrophy, without inflammatory signs (Fig.  4.36). Distribution is sheet-like and best assessed in the axial plane. Skin abnormalities may lead to disproportionate skeletal growth, such as limb-length discrepancy or facial underdevelopment. Articular involvement is the most common extracutaneous manifestation in LJS, affecting approximately 20% of

the patients. Arthritis is usually nonerosive and asymmetric, even though erosive arthritis is occasionally found, and early development of contractures, subluxations, and tenosynovitis may occur (Figs.  4.38 and 4.39); US and MRI are the imaging methods of choice for assessment of articular manifestations. Reduced thickness of the soft tissues of the digital extremities, acro-osteolysis (lytic changes of the distal phalanges of the hands and feet – Fig. 4.40), and calcifications of the skin and subcutaneous tissue (most common in sites exposed to pressure) are late findings. There may also be widening of the periodontal ligament space and edentulism (Fig. 4.41).

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b

Fig. 4.36  Scleroderma “en coup de sabre” affecting the left hemiface of a 6-year-old male. In (a), transverse T1-WI demonstrates low signal intensity of the affected skin and subcutaneous tissue, with full-­ thickness atrophy of the soft tissues of the forehead and scalp. In (b),

volume-rendered reconstruction of a three-dimensional sequence displays the typical lesion of this type of scleroderma, with a band-like depression of the skin surface affecting the left supraorbital region and the scalp

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Fig. 4.37  Parry-Romberg syndrome in an adult patient, with 10 years of evolution. The upper image is a transverse CT section displaying marked atrophy of the right hemiface at the expense of the skin and subcutaneous tissue. In the lower image, a volume-rendered reconstruc-

tion shows facial hemiatrophy with extensive wasting of the soft tissues and prominence of the zygomatic arch under the skin surface. These findings are similar to those seen in the juvenile form of the disease

Fig. 4.38  Radiographs of the left hand of a 5-year-old boy with juvenile scleroderma and sclerodactyly. In spite of the absence of erosive arthropathy, flexion deformities are already present, affecting the proxi-

mal interphalangeal joints from the second to the fifth digits. Diffuse osteoporosis is also evident

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4.3.4 Mixed Connective Tissue Disease

Fig. 4.39  Transverse fat sat T2-WI of the right wrist of a young female with scleroderma shows increased signal intensity in the soft tissues adjacent to the extensor and flexor tendons, related to tenosynovitis. The tendons present normal appearance

Pediatric mixed connective tissue disease (MCTD) is characterized by overlapping features of juvenile idiopathic arthritis (JIA), systemic lupus erythematosus, systemic sclerosis, and dermatomyositis and/or polymyositis. It is a rare disease entity, even though almost one-fourth of all described patients are children, presenting a more benign course if compared to the adult type. Affected individuals typically present Raynaud phenomenon and positivity for anti-U1 RNP antibody, with variable disease course and outcome. Disease onset usually occurs between the end of childhood and the beginning of adolescence, and females are predominantly affected. Arthritis and/or arthralgia are common, of varied severity. Myositis may affect up to two-thirds of these patients, indistinguishable on imaging

Fig. 4.40  Radiographs of the hands of a 16-year-old female with juvenile scleroderma disclosing bilateral resorption of the distal phalanges and thinning of the soft tissues of the extremities of the fingers (acro-osteolysis)

4.3 Pediatric Collagen Vascular Disorders

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Fig. 4.41  Widening of the periodontal ligament space is seen in the jaw of a patient with juvenile scleroderma, with periapical lucencies in several teeth. Partial edentulism is already present, even prior to the eruption of the third molars

from that found in JDM. It has been described that dermatomyositis-related findings, commonly found at presentation, tend to involute during the course of the disease, while sclerodermarelated abnormalities increase in frequency with time.

Key Points

• Unlike its adult counterparts, juvenile spondyloarthritis presents predominantly peripheral joint involvement at onset, while spondylitis and/or sacroiliitis are late findings. As radiographs are often normal, US and MRI – mainly the latter – are the most useful methods for the assessment of peripheral arthritis. MRI is the method of choice for evaluation of sacroiliitis. • Active lesions in sacroiliitis include osteitis, synovitis, retro-articular enthesitis, and capsulitis, while structural lesions comprise bone erosions, subchondral sclerosis, fatty replacement, and ankylosis, all of them well assessed with MRI. • Distinctive features of juvenile ankylosing spondylitis include asymmetric oligoarthritis and enthesitis. Sacroiliitis is prototypical, similar to that of the adult form of the disease. • Periostitis is more prominent, and there is less enthesopathy in juvenile psoriatic arthritis if com-

pared to juvenile ankylosing spondylitis.  Patients usually present asymmetric oligoarthritis of the distal interphalangeal joints of the hands, and dactylitis is a typical finding. • Arthritis associated with inflammatory bowel disease in children is most often an oligoarthritis that affects peripheral joints. Only a minority of these patients will present sacroiliitis and/or spondylitis. • Reactive arthritis usually presents as a self-limited monoarthritis or oligoarthritis, involving most often the lower limbs. Erosive arthropathy, enthesitis, and sacroiliitis are occasionally found. • Osteoarticular manifestations are not among the most prominent features of pediatric collagen vascular disorders. Nevertheless, from an imaging standpoint, there are some noteworthy features. Myositis and dystrophic calcinosis are typical of juvenile dermatomyositis, while cutaneous and/or subcutaneous areas of inflammation are characteristic of juvenile scleroderma, leading to skin atrophy and fibrosis. Nonerosive arthritis, tenosynovitis, and avascular necrosis are the most common findings in patients with juvenile systemic lupus erythematosus. Arthritis and myositis are not uncommon in pediatric mixed connective tissue disease.

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Recommended Reading 1. Aquino MR, Tse SM, Gupta S, Rachlis AC, Stimec J. Whole-body MRI of juvenile spondyloarthritis: protocols and pictorial review of characteristic patterns. Pediatr Radiol. 2015;45:754–62. 2. Babyn P, Doria AS. Radiologic investigation of rheumatic diseases. Rheum Dis Clin N Am. 2007;33:403–40. 3. Buchmann RF, Jaramillo D. Imaging of articular disorders in children. Radiol Clin N Am. 2004;42:151–68. 4. Burgos-Vargas R.  The juvenile-onset spondyloarthritides. Rheum Dis Clin N Am. 2002;28:531–60. 5. Daldrup-Link HE, Steinbach L. MR imaging of pediatric arthritis. Magn Reson Imaging Clin N Am. 2009;17:451–67. 6. Eshed I, Bollow M, McGonagle DG, Tan AL, Althoff CE, Asbach P, et al. MRI of enthesitis of the appendicular skeleton in spondyloarthritis. Ann Rheum Dis. 2007;66:1553–9. 7. Fink AZ, Gittler JK, Nakrani RN, Alis J, Blumfield E, Levin TL.  Imaging findings in systemic childhood diseases presenting with dermatologic manifestations. Clin Imaging. 2018;49:17–36. 8. Hartman GH, Renaud DL, Sundaram M, Reed AM.  Spondyloarthropathy presenting at a young age: case report and review. Skelet Radiol. 2007;36:161–4. 9. Herregods N, Dehoorne J, Joos R, Jaremko JL, Baraliakos X, Leus A, et al. Diagnostic value of MRI features of sacroiliitis in juvenile spondyloarthritis. Clin Radiol. 2015;70:1428–38. 10. Herregods N, Jaremko JL, Baraliakos X, Dehoorne J, Leus A, Verstraete K, et  al. Limited role of gadolinium to detect active sacroiliitis on MRI in juvenile spondyloarthritis. Skelet Radiol. 2015;44:1637–46. 11. Horger M, Fierlbeck G, Kuemmerle-Deschner J, Tzaribachev N, Wehrmann M, Claussen CD, et al. MRI findings in deep and generalized morphea (localized scleroderma). AJR Am J Roentgenol. 2008;190:32–9. 12. Jadon DR, Ramanan AV, Sengupta R. Juvenile versus adult-onset ankylosing spondylitis  – clinical, radiographic, and social outcomes. A systematic review. J Rheumatol. 2013;40:1797–805. 13. Jaremko JL, Liu L, Winn NJ, Ellsworth JE, Lambert RG. Diagnostic utility of magnetic resonance imaging and radiography in juvenile spondyloarthritis: evaluation of the sacroiliac joints in controls and affected subjects. J Rheumatol. 2014;41:963–70. 14. Johnson K, Davis PJ, Foster JK, McDonagh JE, Ryder CA, Southwood TR.  Imaging of muscle disorders in children. Pediatr Radiol. 2006;36:1005–18. 15. Lalani TA, Kanne JP, Hatfield GA, Chen P.  Imaging findings in systemic lupus erythematosus. Radiographics. 2004;24:1069–86. 16. Lee EY, Sundel RP, Kim S, Zurakowski D, Kleinman PK. MRI findings of juvenile psoriatic arthritis. Skelet Radiol. 2008;37:987–96.

17. Lin C, MacKenzie JD, Courtier JL, Gu JT, Milojevic D. Magnetic resonance imaging findings in juvenile spondyloarthropathy and effects of treatment observed on subsequent imaging. Pediatr Rheumatol Online J. 2014. https://doi.org/10.1186/1546-0096-12-25. 18. Mier RJ, Shishov M, Higgins GC, Rennebohm RM, Wortmann DW, Jerath R, et  al. Pediatric-onset mixed connective tissue disease. Rheum Dis Clin N Am. 2005;31:483–96. 19. Orr KE, Andronikou S, Bramham MJ, Holjar-Erlic I, Menegotto F, Ramanan AV.  Magnetic resonance imaging of sacroiliitis in children: frequency of findings and interobserver reliability. Pediatr Radiol. 2018;48:1621–8. 20. Pruthi S, Thapa MM. Infectious and inflammatory disorders. Magn Reson Imaging Clin N Am. 2009;17:423–38. 21. Rennie WJ, Jans L, Jurik AG, Sudoł-Szopińska I, Schueller-­ Weidekamm C, Eshed I. Anterior chest wall in axial spondyloarthritis: imaging, interpretation, and differential diagnosis. Semin Musculoskelet Radiol. 2018;22:197–206. 22. Sudoł-Szopińska I, Jans L, Jurik AG, Hemke R, Eshed I, Boutry N.  Imaging features of the juvenile inflammatory arthropathies. Semin Musculoskelet Radiol. 2018;22:147–65. 23. Tomasová Studynková J, Charvát F, Jarosová K, Vencovsky J. The role of MRI in the assessment of dermatomyositis and polymyositis. Rheumatology (Oxford). 2007;46:1174–9. 24. Uson J, Loza E, Möller I, Acebes C, Andreu JL, Batlle E, et  al. Recommendations for the use of ultrasound and magnetic resonance in patients with spondyloarthritis, including psoriatic arthritis, and patients with juvenile idiopathic arthritis. Reumatol Clin. 2018;14:27–35. 25. Wagner-Weiner L.  Pediatric rheumatology for the adult rheumatologist. J Clin Rheumatol. 2008;14:109–19. 26. Weiss PF, Chauvin NA, Roth J.  Imaging in juvenile spondyloarthritis. Curr Rheumatol Rep. 2016. https://doi.org/10.1007/ s11926-016-0624-6. 27. Weiss PF, Xiao R, Biko DM, Chauvin NA. Assessment of sacroiliitis at diagnosis of juvenile spondyloarthritis by radiography, magnetic resonance imaging, and clinical examination. Arthritis Care Res (Hoboken). 2016;68:187–94. 28. Weiss PF, Xiao R, Biko DM, Johnson AM, Chauvin NA. Detection of inflammatory sacroiliitis in children with magnetic resonance imaging: is gadolinium contrast enhancement necessary? Arthritis Rheumatol. 2015;67:2250–6. 29. Weiss PF, Xiao R, Brandon TG, Biko DM, Maksymowych WP, Lambert RG, et  al. Radiographs in screening for sacroiliitis in children: what is the value? Arthritis Res Ther. 2018. https://doi. org/10.1186/s13075-018-1642-8. 30. Zulian F.  Systemic sclerosis and localized scleroderma in childhood. Rheum Dis Clin N Am. 2008;34:239–55.

5

Imaging of Infectious Arthropathies in Children

5.1

Introduction

Osteoarticular infection in children often poses a diagnostic challenge, so much greater as the younger is the patient. Although joint aspiration remains indispensable for definitive diagnosis of septic arthritis (as well as tissue biopsy and/or culture data for tuberculous arthritis), imaging is a valuable tool in the workup of these patients. No matter the etiologic agent, early and accurate definition of the infectious origin of the arthritis is paramount in order to minimize structural damage and avoid complications and long-term sequelae. This chapter addresses the articular component of peripheral musculoskeletal infections, namely, pyogenic and tuberculous arthritis, together with the imaging features of transient synovitis of the hip, one of the most important differential diagnoses to consider in daily practice. Spinal infection is part of the subject matter of Chap. 12.

5.2

Pyogenic Arthritis

The term pyogenic arthritis (PA) is used to describe bacterial joint infection, which accounts for approximately 6% of all arthritis in children. PA most often presents as an acute monoarthritis, more frequently found in males less than 3 years of age. The joints of the lower extremities are involved in approximately 75% of the patients, mostly the hips and knees; the ankles, elbows, and shoulders are other important sites of disease. In children younger than 18  months, the process may begin in a metaphyseal focus that disseminates via transphyseal vessels, which are absent in older children, in whom the growth plate would act as a barrier for dissemination (see Chap. 2). However, it has been recently demonstrated that concomitant osteomyelitis and septic arthritis are more frequent than previously thought in older children, being detected on magnetic resonance imaging in 28–55% of such patients with PA, thus impacting current recommendations for imaging in the management of these patients. In addition to hematogenous spread, the most common route of acquisition, less common ways of

contamination include direct inoculation (open wounds, joint punctures, surgery) or dissemination from a contiguous focus in the adjacent soft tissues. Although Staphylococcus aureus remains the most common pathogen in Western countries, the profile differs in low-income countries; in Africa, for example, Salmonella accounts for 40–60% of all PA cases. It is also noteworthy the increasing prevalence of Kingella kingae, mostly in the population less than 4 years of age. Time is a critical prognostic factor in PA, and prompt diagnosis and management are crucial, as delayed recognition and treatment lead to irreversible joint destruction and permanent sequelae. The acute inflammatory response related to bacterial infection causes rapid cartilaginous destruction, and the increase in the intracapsular pressure related to synovial hypertrophy and purulent effusion may lead to joint dislocation and epiphyseal ischemia, mostly in septic hips. Definitive diagnosis relies on aspiration and analysis of the synovial fluid, which must be performed as soon as PA is suspected. The role of imaging studies – namely, magnetic resonance imaging – has gained importance because of the well-documented association with osteomyelitis in an expressive proportion of patients with PA, so that accurate staging and depicting of associated abnormalities are vital for preoperative planning. Nevertheless, none of the available imaging methods are able to distinguish infectious from noninfectious arthritis, and a normal imaging evaluation does not necessarily rule out articular infection in an appropriate clinical setting. Radiographs must be obtained in all patients even though this imaging modality is quite insensitive, as irreversible joint damage is usually present by the time that radiographic abnormalities become evident, 7–10 days after the process has been initiated (Fig. 5.1); however, radiographs are useful to rule out potential alternative causes of pain, such as fractures or tumors, and to detect established osteomyelitis. Additionally, bone destruction may be present from the start if there is concurrent chronic osteomyelitis. Findings related to the early stages of articular infection are fairly ­non-­specific, including joint effusion, widening of the joint space, and soft-tissue swelling (Fig. 5.2). Narrowing of the joint space appears quickly, as well

© Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_5

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Fig. 5.1  Radiographs of the index finger of the right hand of a 6-year-­ old female who sustained an open fracture of the middle phalanx 6 months earlier presenting spontaneous pus drainage from a fistulous orifice and marked soft-tissue swelling. There are signs of chronic

osteomyelitis of the middle phalanx, with extensive osteolysis and bone sequestra involving the medullary cavity and in the distal interphalangeal joint. Destruction of corresponding joint surfaces due to PA is also evident, with lateral deviation of the distal phalanx

Fig. 5.2  A 9-year-old female with acute osteomyelitis of the right distal femur and secondary contamination of the joint cavity of the knee joint. There are no osseous abnormalities on radiographs, although swelling of periarticular soft tissues can be seen, mostly suprapatellar

and more evident in the lateral view. There are also loss of definition of periarticular fat planes and subtle widening of the joint space. Nonetheless, these are non-specific radiographic findings

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as epiphyseal osteopenia (which is less pronounced than that found in tuberculous arthritis) and peripheral and subchondral bone erosions (Figs. 5.3 and 5.4), which are usually more severe in the hips (Fig. 5.5). Polyarticular PA occurs in less than 10% of all cases (Fig. 5.6). Ultrasonography (US) is very useful for early detection of joint effusion and synovitis in children because it does not involve exposure to ionizing radiation and is performed quickly, non-invasively, and with no need for sedation, being also appropriate for image-guided joint aspiration. It is particularly helpful for the detection of joint effusion in deeply seated joints such as the hip or shoulder, where clinical examination is not effective. In addition to joint effusion (which may vary from clear and hypoechogenic to heterogeneous with suspended debris), hyperemia of the inflamed synovium on Doppler US is also common, but these findings are not specific (Fig.  5.7). US is also able to demonstrate erosions (especially large ones) and dissemination of the infection to adjacent bursae and tendon sheaths. Some authors believe that US and radiographs are sufficient diagnostic imaging in the initial evaluation of the septic hip, as

Fig. 5.4  Radiograph of the proximal portion of the right arm of a young child with bacterial osteomyelitis and secondary contamination of the shoulder joint. There are lytic lesions associated with cortical destruction in the proximal metaphysis, as well as marked swelling of the periarticular soft tissues and widening of the proximal humeral physis

Fig. 5.3  Anteroposterior view of the right hip of a child with PA and disease onset less than 1  month earlier. There is osteoporosis of the proximal femur and narrowing of the coxofemoral joint space, as well as irregularity of the acetabulum. Such findings are compatible with advanced cartilaginous destruction

Fig. 5.5  Pyogenic arthritis of the left hip with poor evolution. There is marked bone destruction with almost complete resorption of the left proximal femoral epiphysis and bone remodeling of the corresponding acetabulum; acetabular protrusion is evident as well, with striking acetabular incongruity. Left-sided osteoporosis is also present

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Fig. 5.6  Radiographs of the left elbow (first image) and of the right shoulder (second image) of a child with multifocal bacterial osteomyelitis and secondary articular contamination. There is metaphyseal osteomyelitis in the left distal and in the right proximal humeri, with permeative osteolysis, periosteal reaction, soft-tissue swelling, and epiphyseal involvement, the latter more evident in the shoulder. Osteomyelitis of the right femur and pyogenic arthritis of the ipsilateral hip were also present (not shown)

Fig. 5.7  US of the hips of two distinct children, both with pyogenic arthritis. The upper images show longitudinal scans of the left hip joint demonstrating hypoechogenic joint effusion associated with irregular synovial thickening. In the lower row, there is heterogeneous material filling the joint cavity of the right hip, representing synovial thickening and joint effusion with suspended debris. The proximal epiphysis of the right femur is irregular and of reduced size, notably if compared to the contralateral one. (Courtesy of Dr. Telma Sakuno, MD, Hospital Universitário da UFSC, Florianópolis, Brazil)

joint effusion along with compatible clinical and laboratory findings is usually enough evidence for surgery without need for advanced imaging. Nevertheless, absence of hip effusion in this clinical setting, on the other hand, does not rule out infection, either because the stage of the process is too early (first 24 hours) or because adjacent osteomyelitis or soft-tissue infection is the real cause of the symptoms. In the light of recent knowledge, further investigation with magnetic resonance imaging is recommended (see below). Contrast-enhanced magnetic resonance imaging (MRI) allows prompt detection of the earliest changes related to PA, with accurate assessment of disease extent that helps in preoperative planning. It is highly sensitive for detecting joint effusion and synovitis, mostly when intravenous contrast is administered, as there is enhancement of the synovium and of the inflamed tissues (Figs. 5.8, 5.9, 5.10, 5.11, 5.12, 5.13, and 5.14); furthermore, contrast-enhanced fat sat T1-WI are unique in demonstrating involvement of the nonossified epiphyseal cartilage (chondritis), which appears as non-­enhancing areas in children less than 18 months old. Erosions and destructive changes of bone and cartilage are also clearly seen (Figs. 5.9, 5.10, 5.11, and 5.12), as well as dissemination of the infectious process to nearby bursae and tendon sheaths. Subchondral bone marrow edema is common and not necessarily indicative of osteomyelitis, as it may be merely related to reactive (noninfectious) osteitis. Osteomyelitis is more likely if the edematous areas extend far beyond the subchondral bone, notably if there is prominent low signal intensity on T1-WI (Figs.  5.8, 5.12, 5.13, and 5.14). Epiphyseal extension of bone marrow edema related to metaphyseal osteomyelitis has been described as an unreliable predictor of whether a joint effusion is reactive or pyogenic; nevertheless, adjacent joint effusions identified

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Fig. 5.8  Coronal STIR image (upper left image), transverse T1-WI (upper right image), and post-contrast fat sat T1-WI in the coronal and sagittal planes (lower images) of the hips and thighs of a 9-year-old female with right-sided septic coxofemoral arthritis. There are joint effusion in the

right hip and bone marrow edema in the ipsilateral femur, which extends far beyond the subchondral bone, reaching the mid-diaphysis, indicative of associated osteomyelitis. Post-gadolinium enhancement of the edematous bone and of the proximal quadriceps is also evident

Fig. 5.9  Coronal T1-WI and fat sat T2-WI (upper row) of the left hip of a 12-year-old girl with PA reveal joint effusion and cartilaginous thinning, as well as edematous changes of the soft tissues of the proximal thigh and of the subchondral bone marrow of the acetabulum. Transverse post-contrast fat sat T1-WI (lower row) disclose intense

enhancement of the thickened synovium and extensive destruction of the anterosuperior acetabulum, with cortical discontinuity and infiltration of the adjacent soft tissues, as well as contrast enhancement in the affected bone and soft tissues. This appearance may resemble aggressive bone tumors, like Ewing’s sarcoma

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Fig. 5.9 (continued)

Fig. 5.10  Transverse post-gadolinium fat sat T1-WI of the left hip of a 13-year-old male with PA. Heterogeneous joint effusion, marked synovial thickening, and infected collections in the soft tissues of the proximal thigh can be seen, with post-contrast enhancement. The femoral head is deformed, and its appearance is suggestive of slippage of the proximal femoral epiphysis as a complication of septic arthritis

on MRI in children with osteomyelitis should be presumed to be septic until proven otherwise, and concomitant septic arthritis is more likely if osteomyelitis occurs at a site with intra-­articular metaphysis. Cortical discontinuity, periosteal reaction, intraosseous abscesses, and soft-tissue collections are typical of osteomyelitis (Figs. 5.9, 5.12, 5.13, 5.14, 5.15, 5.16, 5.17, and 5.18). MRI has been recommended as the imaging modality of choice when evaluating bone involvement in septic arthritis given that, unlike previously thought, it has been shown that concomitance of osteomyelitis and PA is statistically significant. Moreover, some authors advocate that, if there is a strong suspicion of osteoarticular infection, MRI should routinely be used as the only investigation and, in particular for PA patients, the sole use of US is discouraged. If MRI is performed for suspected osteomyelitis, the nearest joint should routinely be specifically investigated. Furthermore, MRI is effective for early and accurate diagnosis of deeply seated soft-tissue infections around the hip and the pelvic girdle and may avoid a useless joint aspiration. Lastly, in septic hips, contrast-enhanced MRI can provide unique information related to the perfusion of the femoral head, as there is an increased risk of osteonecrosis in this setting. Nevertheless, limited availability of MRI and the potential need for sedation and/or anesthesia in children are deterrents to a more widespread utilization. Computed tomography (CT) has restricted usefulness in the assessment of PA in pediatric patients (see Chap. 1). It is usually reserved for selected cases, most commonly performed as an adjunct to MRI for osseous assessment or to evaluate anatomically complex joints (Figs. 5.19, 5.20, 5.21, 5.22, and 5.23). Intravenous contrast is recommended in this setting, as there is post-contrast enhancement in the inflamed synovium and soft tissues (Figs. 5.20 and 5.23). If there is associated osteomyelitis, CT is invaluable to demonstrate bone destruction, periosteal neoformation and the

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a

b

c

d

Fig. 5.11  Female adolescent with a chronic low-grade infection in the right forefoot. In (a) and (b), PET-CT demonstrates intense enhancement adjacent to the third metatarsophalangeal joint, initially interpreted as an infection of the periarticular soft-tissues with secondary involvement of the contiguous bone. MRI performed 3  months later

(coronal STIR image (c) and sagittal post-gadolinium fat sat T1-WI (d)) demonstrates that the infection was primarily articular, with joint effusion, synovitis, and erosions in the head of the third metatarsal bone and edematous changes of the bone and of the adjacent soft tissues

Fig. 5.12  MRI of the left ankle of a 12-year-old male with PA. T1-WI (upper left image) and STIR image (upper right image) disclose tibiotalar joint effusion, metaphyseal osteomyelitis of the distal tibia, and a small juxtaphyseal intraosseous abscess, anteriorly situated. Post-­

gadolinium fat sat T1-WI (lower images) demonstrate the intraosseous abscess with hypointense content and peripheral enhancement draining to the joint cavity through a cortical break. Synovial enhancement is also present, distinguishing the thickened synovium from the joint effusion

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Fig. 5.12 (continued)

Fig. 5.13  MRI of the same patient as in Fig.  5.2, performed on the gadolinium enhancement, as well as subperiosteal abscesses, extensive same day (upper row, coronal fat sat T2-WI and sagittal T2-WI; lower edema of the periarticular soft tissues, and contamination of the joint row, coronal and sagittal post-gadolinium fat sat T1-WI). There is dif- cavity, with joint effusion and synovitis fuse infiltration of the bone marrow of the distal femur, with post-­

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Fig. 5.14  MRI of the left hip of a child with PA (upper left image, coronal fat sat T2-WI; remaining images – transverse post-gadolinium fat sat T1-WI). There is a large and heterogeneous joint effusion on fat sat T2-WI, with extensive bone marrow edema in the proximal femur

and acetabulum and edematous changes in the adjacent soft tissues. Post-gadolinium images display a large, complex soft-tissue abscess surrounding the hip, with thick and irregular enhancement, as well as adjacent myositis

Fig. 5.15  Coronal T2-WI (left) and post-gadolinium fat sat T1-WI (right) of the left sacroiliac joint of a 13-year-old male with suspected PA of the right hip and a normal US scan. There are fluid within the sacroiliac joint space and edematous changes of the adjacent soft tissues, as well as a well-delimited intraosseous abscess in the subchon-

dral bone of the upper third of the sacral surface surrounded by extensive bone marrow edema. Post-contrast images display diffuse enhancement of the aforementioned edematous abnormalities and peripheral enhancement inside the intraosseous abscess

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Fig. 5.15 (continued)

Fig. 5.16  MRI of the right hip of a 10-year-old boy who underwent surgical treatment of PA, performed to clarify signs of ongoing sepsis. On coronal post-gadolinium fat sat T1-WI, one can identify a small joint effusion associated with synovial enhancement, extensive osteomyelitis of the ipsilateral iliac bone and a large, complex abscess

involving the iliac and gluteal muscles, with surrounding myositis. There are also diffuse post-contrast enhancement of the infected bone, peripheral enhancement of the soft-tissue abscess, and feathery enhancement of the inflamed muscles

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a

b

Fig. 5.17  A 9-year-old male with concomitant PA and osteomyelitis of the left hip. In (a), coronal (left) and axial (right) fat sat T2-WI show, in addition to moderate joint effusion, extensive bone marrow edema affecting the ilium and, more importantly, the ischium, as well as several soft-tissue collections in the periarticular muscles, more evident in

the obturator internus, and widespread myositis. In (b), anteroposterior radiograph of the pelvis performed 1  month later displays marked osteoporosis in the left hip and bone destruction affecting the ischium, with cortical irregularity and permeative lytic lesions; mild narrowing of the ipsilateral coxofemoral joint space is also present

presence of sequestra (Figs. 5.20, 5.21 and 5.23). Moreover, CT is the best imaging method to depict gas bubbles in the infected tissues, which are indicative of the bacterial nature of the infection (Fig. 5.19). Despite its high sensitivity, bone scintigraphy also plays a limited role in the assessment of articular infection and has been largely supplanted by US and MRI in this setting

(see Chap. 1). Nevertheless, because of its ability to assess the whole body in a single study, bone scintigraphy may be useful to detect “occult” sites of infection in multifocal PA. Increased uptake is usually present in the affected joint, although decreased uptake may be seen in the epiphysis if avascular necrosis ensues (which is more frequently seen in the hip). Even though it has been suggested that PET

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Fig. 5.18  A 9-year-old male with PA of the left hip and a cutaneous fistula in the inguinal region. Coronal and axial fat sat T2-WI (left) and post-gadolinium T1-WI (right) disclose joint effusion and synovitis, extensive bone marrow edema in the proximal femur with heterogeneous post-contrast enhancement (related to osteomyelitis), and widespread myositis, characterized by muscle edema and ill-defined

enhancement. There is an elongated and loculated abscess in the anterior soft tissues of the root of the thigh, which is more evident in the axial post-gadolinium T1-WI, with a thin peripheral rim of enhancement. The small area of enhancing bone marrow edema seen in the roof of the acetabulum may either correspond to focal osteomyelitis or be merely related to reactive osteitis

and/or CT may be useful in the assessment of the posttreatment course of PA, as MRI can be abnormal even after successful management of the infection, the role of this imaging modality in the evaluation of septic joints has not yet been established (Fig. 5.11). Long-term sequelae are found in up to 40% of children with PA.  Abnormal joint alignment and/or joint

deformities (Figs. 5.24 and 5.25), premature physeal closure (Figs. 5.25, 5.26 and 5.27), limb-length discrepancy (Fig.  5.27), premature osteoarthritis, avascular necrosis (Figs. 5.27 and 5.28), and, in advanced cases, bony ankylosis (in opposition to the fibrous type of ankylosis seen in tuberculous arthritis  – Fig.  5.29) are among the most important complications.

5.3  Tuberculous Arthritis

135

5.3

Tuberculous Arthritis

Fig. 5.19  A 9-year-old male with PA of the right hip and septicemia. CT scan reveals joint effusion, marked swelling of periarticular soft tissues, densification of the subcutaneous fat, and juxtaarticular abscesses. Gas bubbles can be seen in the collections, indicative of the bacterial nature of the infection. (Courtesy of Dr. Arthemízio Rocha, MD, Hospital de Base do Distrito Federal, Brasília, Brazil)

Tuberculosis (TB) is an infectious condition known since ancient times. Even though several strains of mycobacteria may cause TB, Mycobacterium tuberculosis is the most important of them all. There has been a global increase in the incidence of TB in recent times that may be attributable to several factors, including the HIV and/or AIDS pandemic and immigration from endemic areas. Osteoarticular disease accounts for different percentages of extrapulmonary TB in different populations (varying from 10% to 35%), and it is noteworthy that less than half of these patients have concomitant pulmonary disease. Musculoskeletal TB is more common in older children and young adults where TB is endemic, presenting in older persons in developed countries; spinal involvement, however, is found even in small children. Only the involvement of the peripheral joints will be discussed in the following paragraphs, as spinal involvement, the most common presentation of musculoskeletal TB, is part of the subject matter of Chap. 12.

Fig. 5.20 CT scan of the left knee of a 2-year-old child with PA. Transverse images with bone (left images) and soft-tissue (central images) window settings and volume-rendered reconstructions (right images) reveal an extensive lytic lesion of the proximal metadiaphysis

of the tibia, which extends across the growth plate to the proximal epiphysis. There is wide discontinuity of the posterior cortex, with bone sequestra in the medullary cavity, joint effusion, and a complex abscess in the posterior soft tissues of the proximal leg

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Fig. 5.21  Neonatal septic arthritis of the right shoulder. In the first image, radiograph of the affected joint reveals metaphyseal osteomyelitis of the proximal humerus, with a large intraosseous abscess and extensive periosteal reaction. In the following images, transverse CT sections corroborate the above described findings, disclosing bone

a

Fig. 5.22  A 17-year-old patient with PA of the right facet joint of L3– L4. In (a) and (b), transverse CT images evidence blurring and hypodensity of the soft tissues adjacent to the infected joint, without evidence of bone erosions. Transverse T2-WI (c) and post-gadolinium fat sat T1-WI (d) show fluid in the joint space extending deep to the

destruction and cortical rupture. There is evidence of contamination of the joint cavity, with a large joint effusion and abscesses in the adjacent soft tissues. (Courtesy of Dr. Arthemízio Rocha, MD, Hospital de Base do Distrito Federal, Brasília, Brazil)

b

ipsilateral ligamentum flavum, with discontinuity of the latter. Edema of the paravertebral soft tissues is also seen, as well as a right-sided posterior epidural phlegmon, with contralateral displacement of the thecal sac. The inflamed tissues exhibit diffuse post-contrast enhancement

5.3  Tuberculous Arthritis

c

137

d

Fig. 5.22 (continued)

a

Fig. 5.23  Transverse CT images (a) and (b) and sagittal reformatted images (c) of the right ankle of a 7-year-old female with tibiotalar PA and osteomyelitis of the tarsal bones. Destructive lesions in the talus and in the tarsal navicular bone are evident in the image with bone window settings (a), with sequestra in the affected bones and in the

adjacent soft tissues. Diffuse edema of the periarticular soft tissues is evident in the images with soft-tissue window settings (b) and (c), as well as a large tibiotalar effusion. Post-contrast enhancement is seen in the thickened synovium and in the inflamed soft tissues

138

5  Imaging of Infectious Arthropathies in Children

b

c

Fig. 5.23 (continued)

5.3  Tuberculous Arthritis

139

Fig. 5.24  Late-stage sequelae of neonatal PA of the right hip. Radiographs show deformity of the proximal femur, delayed epiphyseal ossification, and remodeling of the acetabulum Fig. 5.25  Radiographs of the right elbow of a 7-year-old male with late-stage sequelae of PA (a). Joint deformity, bone remodeling, and articular incongruity can be seen, with radial shortening due to premature physeal closure. In (b), pelvic radiograph of a patient with late-stage sequelae of PA of the right hip shows coxofemoral dislocation and superior migration of the ipsilateral femur. The femoral head is articulated with the iliac bone, and the ipsilateral acetabulum is poorly developed, which are indicative of long-standing disease

a

b

140

5  Imaging of Infectious Arthropathies in Children

Fig. 5.26  Radiographs of the left shoulder of a young child with PA. The image on the left, obtained during the active stage of the disease, shows metaphyseal lucencies and cortical irregularity due to

osteomyelitis. The second radiograph, taken after healing has occurred, reveals early fusion of the proximal humeral physis and marked residual deformity

Tuberculous arthritis is typically monoarticular, though multifocal musculoskeletal TB may be found in 5–10% of all skeletal cases. The typical presentation is that of a slowly progressive monoarthritis that affects weight-bearing joints, such as the knees and hips, even though any joint can be involved. In extraspinal TB, osteoarticular involvement is more frequent than isolated osteomyelitis, and infection of the joint cavity is usually due to transphyseal dissemination of an active tuberculous focus in the metaphysis of a long bone, consisting of both osteomyelitis and arthritis. This pattern is characteristic of osteoarticular TB, highlighting the importance of being acquainted with tuberculous osteomyelitis to better understand the findings of tuberculous arthritis. Furthermore, there may be abscesses around the joint or adjacent to bone (“cold abscesses”), which may occasionally rupture and lead to the development of sinus tracts that are very characteristic of musculoskeletal TB. Early-stage radiographic findings are non-specific and include widening of the joint space and soft-tissue swelling.

The triad of periarticular osteoporosis, peripheral bone erosions, and relative preservation of the joint space (Phemister triad) is classic for tuberculous arthritis (Figs. 5.30 and 5.31). Periosteal reaction, cortical irregularity, and lytic lesions may also be present (Figs. 5.30, 5.32, 5.33, and 5.34), usually with minimal to absent bone sclerosis. Chronic granulomatous synovitis leads to joint effusion, synovial thickening, and pressure erosions; nevertheless, as tuberculous arthritis lacks the proteolytic enzymes found in pyogenic arthritis, progression of joint space narrowing is slower in the former. Hyperemia is the cause of marked juxtaarticular osteoporosis, epiphyseal overgrowth and accelerated bone maturation (Figs. 5.31, 5.35, 5.36, and 5.37), premature and/or asymmetric physeal closure (Fig. 5.37), and widening of the intercondylar notch of the affected knees (Fig.  5.36). There is progressive destruction of the subchondral bone (Figs. 5.37, 5.38, and 5.39), and extensive osteochondral damage may eventually lead to fibrous ankylosis. Subluxation of the femoral head is occasionally seen in tuberculous arthritis

5.3  Tuberculous Arthritis

141

Fig. 5.27  Late-stage sequelae of PA of the right hip, probably complicated with avascular necrosis. Scanogram demonstrates shortening of the right lower limb due to deformity of the ipsilateral hip, characterized by a mushroomshaped femoral head, shortening and broadening of the femoral neck, flattening of the acetabulum, and early closure of the growth plate of the femoral head, with consequent joint incongruity

of the hip joint, just like in PA (Fig.  5.39). The metaphyses of long bones (mainly the femora and the tibiae) are the most frequently affected sites in tuberculous osteomyelitis (Figs. 5.30, 5.32 and 5.33), but involvement of other sites (such as the ribs, patella, sternum, and skull) is not rare (Fig. 5.40). In children, there may be eccentric, well-­ delimited round or ovoid lytic lesions, which are frequently multifocal and usually lack sclerotic borders, presenting metaphyseal expansion and periosteal reaction (Fig. 5.41);

the term cystic TB (also known as osteitis cystica tuberculosa multiplex or multifocal tuberculous osteomyelitis) is often used to describe these multiple expansile metaphyseal lesions. As mentioned above, transphyseal dissemination is more common in TB than in bacterial infections (Figs. 5.30 and 5.32); a cortical break may be present, disseminating the infection directly into the joint cavity, and sequestra are occasionally found. Generally speaking, tuberculous osteomyelitis lacks sclerosis and has less sequestra and periosteal

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Fig. 5.28  Sagittal post-gadolinium fat sat T1-WI of the right hip of a 3-year-old child with PA. In addition to the abnormalities usually found in septic joints, there is marked decrease in the enhancement of the

proximal femoral epiphysis, as well as loss of its sphericity, related to avascular necrosis

reaction if compared to pyogenic osteomyelitis. The term spina ventosa is used to describe a peculiar form of tuberculous osteomyelitis that is more common in children and usually affects the small bones of hands and feet (tuberculous dactylitis), characterized by osseous destruction, thickening of the overlying periosteum, and fusiform appearance of the bone. These lesions appear as cyst-like cavities on radiographs, leading to diaphyseal widening and swelling of the surrounding soft tissues. MRI is the optimal imaging method for early demonstration of osteoarticular tuberculosis, revealing bone marrow edema adjacent to the affected joint, joint effusion (often heterogeneous in appearance), synovial thickening, cartilaginous damage, and bone erosions (Fig. 5.42). Administration of intravenous contrast is formally recommended, just like in pyogenic arthritis. Synovial proliferation may be hypointense or hyperintense on T2-weighted images (T2-WI), showing moderate to intense post-contrast enhancement when acutely inflamed (Fig. 5.42); nonetheless, chronically inflamed synovium may exhibit little enhancement or no

enhancement at all. If compared to pyogenic arthritis, the erosive component is more prominent in tuberculous arthritis, with relatively less subchondral edema. Furthermore, there may be hemosiderin deposition in the thickened synovium in osteoarticular TB (Fig.  5.42). Tuberculous tenosynovitis commonly involves the hand, with synovial thickening, fluid distention, and hyperintense material on T2-WI within tendon sheaths, occasionally leading to the formation of soft-tissue masses (Fig.  5.42). Tuberculous bursitis usually affects sites exposed to frequent trauma, and the process may extend to adjacent musculoskeletal structures. When present, tuberculous abscesses usually display thin and smooth walls, while the walls of bacterial abscesses are most often thicker and irregular; peripheral post-gadolinium enhancement is seen in both conditions. Intraosseous abscesses in TB are most often hypointense on T1-WI and hyperintense on T2-WI, also presenting post-gadolinium enhancement; the presence of hypointense areas on T2-WI usually indicates caseous transformation and is very suggestive of tuberculous osteomyelitis. “Rice bodies” (fibrinoid

5.3  Tuberculous Arthritis

143

Fig. 5.29  Late-stage sequelae of PA of the right wrist. There is evidence of right-sided proximal row carpectomy, with fusion of the bones of the distal row and the adjacent metacarpals, as well as residual deformity and atrophy of the ipsilateral bones

necrosis of the hypertrophic synovium with fibrin precipitation and development of micronodules) similar to those seen in juvenile idiopathic arthritis can be identified within the joints, bursae, and tendon sheaths. CT is very useful to demonstrate bone sequestra (Fig. 5.43) and soft-tissue calcifications, the latter being typical of chronic osteoarticular TB; the advantages and drawbacks of CT in the assessment of tuberculous arthritis are similar to those above described for pyogenic arthritis.

Just like in PA, US is helpful in the assessment of tuberculous arthritis in children, being also useful to guide invasive joint procedures. Common findings include joint effusion (which may be heterogeneous in appearance), synovial thickening and/or hyperemia, and soft-tissue swelling; superficially located erosions may be seen. Soft-tissue abscesses appear as round and/or oval masses with varied echogenicity depending on their content, presenting peripheral hyperemia on Doppler studies and posterior acoustic enhancement (Fig. 5.44).

144

Fig. 5.30  Tuberculous arthritis of the left knee in a young child. Phemister triad is present, with periarticular osteoporosis, predominantly peripheral erosions, and relative preservation of the joint space.

5  Imaging of Infectious Arthropathies in Children

Metaphyseal and epiphyseal lytic lesions are seen in the distal femur, representing active osteomyelitis (transphyseal spread)

5.4

Fig. 5.31  Increased size and osteoporosis of the epiphyses are seen in this anteroposterior view of the right knee of a child with tuberculous arthritis, with preservation of the joint space and swelling of the periarticular soft tissues

Transient Synovitis of the Hip

Transient synovitis of the hip (TSH), also referred to as toxic synovitis, is an acute condition characterized by joint effusion and non-specific synovial proliferation in the hip joint. It is one of the main differential diagnoses of septic arthritis and the most frequent cause of acute hip pain in children from 3 to 10 years of age, occurring bilaterally in up to 25% of the patients. Diagnosis of TSH is one of exclusion and its etiology is unknown. In most cases, prognosis is good, and affected children will have complete recovery with conservative treatment. The main diagnostic challenge is distinguishing TSH from infectious arthritis: the clinical picture and the imaging findings may be similar, but symptoms are usually more acute and severe in the latter. If left untreated, septic arthritis follows a relentless course, with abnormal laboratory tests; conversely, fever in children with TSH is usually low or absent, and there will be no clinical or laboratory evidence of systemic disease. In TSH, radiographs are normal or show non-specific findings, such as mild osteoporosis of the proximal femur, widening of the joint space, and obliteration of fat planes around the hip. Radiographs are especially recommended for children with less than 1  year of age and for those

5.4  Transient Synovitis of the Hip

Fig. 5.32  Radiographs of the right knee disclosing posterolateral lytic lesions involving the metaphysis and the epiphysis of the distal femur representing transphyseal dissemination of tuberculous osteomyelitis

145

and concomitant tuberculous arthritis. There are discontinuity of the posterior cortex and diffuse swelling of the periarticular soft tissues, as well as posterior periosteal reaction along the distal femoral diaphysis

Fig. 5.33  Radiographs of the left knee of a 2-year-old child. There is a well-delimited lytic lesion adjacent to the anterolateral physis in the proximal tibial metaphysis. Tuberculous osteomyelitis

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5  Imaging of Infectious Arthropathies in Children

Fig. 5.34  Lytic lesion in the medial portion of the distal epiphysis of the right femur, ill-defined, associated with diffuse swelling of periarticular soft tissues, representing tuberculous osteomyelitis and concomitant arthritis

Fig. 5.35  Lateral views of both knees of a 5-year-old child with left-sided tuberculous arthritis. The left epiphyses are osteopenic and show increased size when compared to the contralateral ones; ipsilateral soft-tissue swelling is also evident

5.4  Transient Synovitis of the Hip

147

Fig. 5.36  Tuberculous arthritis of the left knee. There is increased size of the epiphyses and periarticular osteoporosis in the affected knee, with widening of the intercondylar notch, findings similar to those of hemophiliac patients. Subtle narrowing of the left joint space is noticeable

Fig. 5.37  Radiograph of the hips of a 15-year-old female with left-­sided tuberculous arthritis. There is narrowing of the left joint space, with irregular joint surfaces, regional osteoporosis, and premature physeal closure in the ipsilateral femur

older than 8 years old because TSH is uncommon in these age groups, in which septic arthritis and child abuse (younger children) and slipped femoral capital epiphysis (older children) should be considered. US is the first line of investigation for patients with TSH, as synovial thickening and even small joint effusions can be detected

(Fig. 5.45) and image-guided joint aspiration may be performed in the same session. MRI is a second-line procedure in TSH, showing joint effusion and mild synovitis without significant bone marrow edema or erosive arthritis (Fig.  5.46). Other imaging studies are rarely used in patients with TSH.

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Fig. 5.38  A 6-year-old male with chronic arthritis in the left knee and a skin fistula. Radiographs disclose advanced destructive arthritis, marked osteoporosis, abnormal shape of the epiphyses, large bone ero-

sions (mainly posterior, along the distal femur and the proximal tibia), and swelling of the regional soft tissues. Osteoarticular tuberculosis

Fig. 5.39  Pelvic radiographs of two distinct children, both with advanced tuberculous arthritis of the left hip joints. Bone destruction with marked periarticular osteoporosis and irregularity of the joint surfaces can be seen, as well as hypoplasia of the left iliac bones and of the

left proximal femora. Pressure erosions can be seen along the medial aspect of the femoral neck in the second radiograph, as well as lateral subluxation of the hip

5.4  Transient Synovitis of the Hip

149

Fig. 5.40  A 3-year-old child with severe malnutrition and palpable nodules in the frontal region. Anteroposterior skull radiograph shows two paramedian lytic lesions in the frontal bone. A small button sequestrum is seen in the left-sided lesion. Tuberculous osteomyelitis

Fig. 5.41 Multifocal tuberculous osteomyelitis affecting the right knee and the left elbow. There are lamellar periosteal reaction in the humerus and solid periosteal apposition in the tibia and in the bones of the forearm,

with mild bone expansion. Periarticular osteoporosis is also present, with lucent lesions in the distal humerus and in the proximal ulna and tibia, as well as soft-tissue nodules along the dorsal aspect of the proximal forearm

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5  Imaging of Infectious Arthropathies in Children

a

b

Fig. 5.42  In (a), fat sat T2-WI (upper images) and post-gadolinium fat sat T1-WI (lower images) disclose tenosynovial involvement of the flexor tendons of the hand in a young male with musculoskeletal TB. The flexor tendon sheaths are distended with heterogeneous hyperintense material on T2-WI containing septa and debris, more prominent in the first, second, and fifth digits, mostly the second one, which display post-gadolinium

enhancement. In (b), coronal gradient-echo images reveal numerous foci of low signal intensity within the tendon sheaths of the second and fifth digits, traditionally considered as related to hemosiderin deposition, even though some authors relate them to “rice bodies” or caseous changes. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)

5.4  Transient Synovitis of the Hip

151

Fig. 5.45  US of the right hip of a child with TSH.  Joint effusion is quite evident, as well as synovial thickening. Nevertheless, these are non-specific findings and do not allow to infer the real nature of the arthritis. Laboratory analysis of the synovial fluid was negative for infection and arthritis subsided with conservative treatment

Key Points

Fig. 5.43  Transverse CT images of the right knee of a child with tuberculous arthritis. Synovial thickening and a large joint effusion are present, as well as a lytic lesion containing a bone sequestrum in the distal femur

Fig. 5.44  Longitudinal US scan of the left hip of a patient with tuberculous arthritis reveals a deeply seated, well-delimited heterogeneous abscess adjacent to the femoral cortex, with posterior acoustic enhancement

• PA is a rapidly progressive disease that leads to accelerated joint destruction. Radiographs are insensitive, and radiographic findings appear late in the course of the disease. Early-stage abnormalities include synovitis and joint effusion. MRI is the most sensitive imaging method, being unique in its ability to demonstrate bone marrow edema, while US is fairly sensitive for soft-tissue abnormalities but insensitive for bone assessment. The added value of imaging modalities other than MRI and US for detection of PA is limited. • It has been shown that concomitance of osteomyelitis and PA is statistically significant, and some authors advocate that, if there is a strong suspicion of osteoarticular infection, MRI should routinely be used as the first (and only) imaging investigation; furthermore, particularly for patients in which there is a strong suspicion of PA, the sole use of US is discouraged. Nevertheless, other authors still believe that US and radiographs are sufficient diagnostic imaging in the initial evaluation of the potentially septic hip. • Radiographic findings typical of tuberculous arthritis include marked periarticular osteoporosis, indolent course, and relative preservation of the joint space. Findings similar to those found in other hyperemic arthropathies can be found, such as epiphyseal overgrowth and early closure of the growth plates. The role of the imaging methods is similar in PA and tuberculous arthritis. • TSH is a self-limited and non-destructive arthritis that affects the hip of children. Joint effusion and synovitis are common, while bone erosions and significant bone marrow edema are notably absent. Radiographs and US are the first line of investigation, while MRI is reserved for selected cases.

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a

b

c Fig. 5.46  Coronal T1-WI (a), STIR image (b), and post-gadolinium fat sat T1-WI (c) of the hips of a 4-year-old child with right-sided TSH. There are moderate joint effusion and synovial thickening in the

Recommended Reading 1. Agarwal A, Aggarwal AN.  Bone and joint infections in children: septic arthritis. Indian J Pediatr. 2016;83:825–33. 2. Arnold JC, Bradley JS. Osteoarticular infections in children. Infect Dis Clin North Am. 2015;29:557–74. 3. Bancroft LW.  MR imaging of infectious processes of the knee. Radiol Clin North Am. 2007;45:931–41. 4. Buchmann RF, Jaramillo D. Imaging of articular disorders in children. Radiol Clin North Am. 2004;42:151–68. 5. Bomanji JB, Gupta N, Gulati P, Das CJ. Imaging in tuberculosis. Cold Spring Harb Perspect Med. 2015; https://doi.org/10.1101/cshperspect.a017814. 6. Chiappini E, Mastrolia MV, Galli L, De Martino M, Lazzeri S. Septic arthritis in children in resource limited and non-resource limited countries: an update on diagnosis and treatment. Expert Rev Anti Infect Ther. 2016;14:1087–96. 7. Cook PC. Transient synovitis, septic hip, and Legg-Calvé-Perthes disease: an approach to the correct diagnosis. Pediatr Clin North Am. 2014;61:1109–18.

right hip, with post-contrast enhancement of the synovium. Erosions and bone marrow edema are notably absent. Complete recovery was achieved with conservative measures

8. Daldrup-Link HE, Steinbach L. MR imaging of pediatric arthritis. Magn Reson Imaging Clin N Am. 2009;17:451–67. 9. De Backer AI, Vanhoenacker FM, Sanghvi DA. Imaging features of extraaxial musculoskeletal tuberculosis. Indian J Radiol Imaging. 2009;19:176–86. 10. Dubois-Ferrière V, Belaieff W, Lascombes P, de Coulon G, Ceroni D. Transient synovitis of the hip: which investigations are truly useful ? Swiss Med Wkly. 2015; https://doi.org/10.4414/ smw.2015.14176. 11. Dwek JR.  The hip: MR imaging of uniquely pediatric disorders. Magn Reson Imaging Clin N Am. 2009;17:509–20. 12. Ernat J, Riccio AI, Fitzpatrick K, Jo C, Wimberly RL. Osteomyelitis is commonly associated with septic arthritis of the shoulder in children. J Pediatr Orthop. 2017;37:547–52. 13. Fabry G. Clinical practice: the hip from birth to adolescence. Eur J Pediatr. 2010;169:143–8. 14. Frank G, Mahoney HM, Eppes SC. Musculoskeletal infections in children. Pediatr Clin North Am. 2005;52:1083–106. 15. Gutierrez K. Bone and joint infections in children. Pediatr Clin N Am. 2005;52:779–94.

Recommended Reading 16. Kritsaneepaiboon S, Andres MM, Tatco VR, Lim CCQ, Concepcion NDP.  Extrapulmonary involvement in pediatric tuberculosis. Pediatr Radiol. 2017;47:1249–59. 17. Laine JC, Kaiser SP, Diab M.  High-risk pediatric orthopedic pitfalls. Emerg Med Clin North Am. 2010;28:85–102. 18. Leonard MK, Blumberg HM.  Musculoskeletal Tuberculosis. Microbiol Spectr. 2017; https://doi.org/10.1128/microbiolspec. TNMI7-0046-2017. 19. Manz N, Krieg AH, Heininger U, Ritz N.  Evaluation of the current use of imaging modalities and pathogen detection in children with acute osteomyelitis and septic arthritis. Eur J Pediatr. 2018;177:1071–80. 20. McCarthy JJ, Noonan KJ.  Toxic synovitis. Skeletal Radiol. 2008;37:963–5. 21. Monsalve J, Kan JH, Schallert EK, Bisset GS, Zhang W, Rosenfeld SB.  Septic arthritis in children: frequency of coexisting unsuspected osteomyelitis and implications on imaging work-up and management. AJR Am J Roentgenol. 2015;204:1289–95. 22. Montgomery NI, Epps HR. Pediatric Septic Arthritis. Orthop Clin North Am. 2017;48:209–16. 23. Montgomery NI, Rosenfeld S.  Pediatric osteoarticular infection update. J Pediatr Orthop. 2015;35:74–81.

153 24. Pattamapaspong N, Sivasomboon C, Settakorn J, Pruksakorn D, Muttarak M.  Pitfalls in imaging of musculoskeletal infections. Semin Musculoskelet Radiol. 2014;18:86–100. 25. Prasad A, Manchanda S, Sachdev N, Baruah BP, Manchanda V.  Imaging features of pediatric musculoskeletal tuberculosis. Pediatr Radiol. 2012;42:1235–49. 26. Pruthi S, Thapa MM. Infectious and inflammatory disorders. Magn Reson Imaging Clin N Am. 2009;17:423–38. 27. Ranson M. Imaging of pediatric musculoskeletal infection. Semin Musculoskelet Radiol. 2009;13:277–99. 28. Schallert EK, Kan JH, Monsalve J, Zhang W, Bisset GS 3rd, Rosenfeld S.  Metaphyseal osteomyelitis in children: how often does MRI-documented joint effusion or epiphyseal extension of edema indicate coexisting septic arthritis? Pediatr Radiol. 2015;45:1174–81. 29. Song KS, Lee SW, Bae KC. Key role of magnetic resonance imaging in the diagnosis of infections around the hip and pelvic girdle mimicking septic arthritis of the hip in children. J Pediatr Orthop B. 2016;25:234–40. 30. Teo HE, Peh WC. Skeletal tuberculosis in children. Pediatr Radiol. 2004;34:853–60.

6

Imaging of Chronic Recurrent Multifocal Osteomyelitis and Autoinflammatory Bone Disorders

6.1

Introduction

ment also differ (see Sect. 6.4, below). Diagnosis of CRMO is one of exclusion, based on clinical data, histopathology, Autoinflammatory bone diseases are disorders characterized and imaging findings, and recent studies indicate an increasby chronic osteitis, bone resorption, and abnormal remodel- ingly important role of imaging in this setting. ing resulting from aberrant unprovoked activation of the Patients with CRMO present recurrent episodes of osteitis innate immune system. The areas affected by chronic bone characterized by pain, swelling, and tenderness in the inflammation are typically culture-negative, with no appar- affected sites. Histological findings are compatible with ent pathogen on histopathology. Inflammatory skin lesions chronic osteomyelitis, but there are no viable microorganare often present, as well as accompanying fever. Chronic isms in samples of the affected tissues, laboratory tests are recurrent multifocal osteomyelitis (CRMO), SAPHO syn- non-specific, and cultures are negative, with no improvement drome, Majeed syndrome, pyoderma gangrenosum and acne on antibiotics. Even though prognosis is overall good, recur(PAPA), deficiency of interleukin-1 receptor antagonist rence is very common; furthermore, persistence of disease (DIRA), CINCA and/or NOMID, and cherubism are among activity into adulthood has been described in a group of the most common autoinflammatory bone disorders in child- patients, and there is a lack of long-term follow-up studies. hood, and CRMO is by far the most studied and well-­ As CRMO is not an infectious condition, the term is recognized of them all. This chapter covers the imaging find- clearly a misnomer – mostly due to the dreaded word “osteoings of some of these diseases, focusing on CRMO as the myelitis” – that may lead to a communication breakdown if prototypical condition of the group. the referring physician is not acquainted with the disease (which is frequently the case in the authors’ experience). Thus, in every and any report containing the term CRMO, the authors include between parentheses the more modern – 6.2 Chronic Recurrent Multifocal and more appropriate – term “chronic non-bacterial osteitis” Osteomyelitis in order to avoid diagnostic confusion. Nevertheless, as CRMO is consecrated by use, for the sake of simplicity, this 6.2.1 Background term will be used in this chapter to refer to chronic non-­ Chronic recurrent multifocal osteomyelitis (CRMO) is a less bacterial osteitis. Although many works call CRMO a “rare known sporadic and idiopathic inflammatory disease of the disease,” it is widely accepted that this disorder is vastly bones that affects most often females from 9 to 14 years of underdiagnosed; there has been a worldwide increase in the age. It is almost exclusively a pediatric condition, even diagnosis in the last decade, which is most probably attributthough adult-onset presentation has been rarely described. able to raised awareness about the condition. CRMO is characterized by (1) multifocal and non-pyogenic bone lesions; (2) undulating clinical course, with exacerbations with remissions; and (3) association with other inflam- 6.2.2 Role of Imaging Methods matory diseases. Associated conditions include psoriasis vulgaris, palmoplantar pustulosis, and inflammatory bowel Imaging findings are not specific but may be very suggestive disease. While some authors describe CRMO as the infantile of the diagnosis. Just like in classic bacterial osteomyelitis, form of SAPHO syndrome, others consider them as distinct the cancellous bone adjacent to the metaphyses (either but related disorders; cutaneous manifestations in CRMO related to epiphyses or apophyses in the long bones) and are not as common as in SAPHO, and sites of bone involve- metaphyseal equivalents (typically in the immature pelvis) is © Springer Nature Switzerland AG 2019 S. L. Viana et al., Joint Imaging in Childhood and Adolescence, https://doi.org/10.1007/978-3-030-11342-1_6

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affected most often, predominantly in the lower limbs. While disease of the long tubular bones is far more common, typical involvement of the clavicle (see Sect. 6.2.3, below) is considered the most specific imaging finding by some authors; even though multifocal disease is usually needed to establish the diagnosis, isolated clavicular disease is used as a criterion in specifically devised (but not yet validated) diagnostic algorithms. Sterile osteitis of the mandible, sternum, ribs, and small tubular bones occurs more rarely. Classic bacterial osteomyelitis and neoplasia are the main differential diagnosis to be considered; the presence of osteitis and/or hyperostosis and multifocal involvement in typical sites are useful findings toward the diagnosis of CRMO. As CRMO is a diagnosis of exclusion, good correlation between clinical and imaging findings and adequate communication between the radiologist and the referring physician are key to a correct diagnosis, requiring close collaboration between the clinical teams. Given that several cardinal features are only evident on imaging, radiologists have an important role in making the diagnosis early in the clinical course, mostly in the more challenging cases. Although initial, atypical, and/or solitary lesions (with the possible exception of clavicular involvement) are usually managed with bone biopsy and further investigation, imaging is of great help in the management of patients with typical and/or multifocal bone lesions and absence of clinical and laboratory evidence of infection, especially if there are concomitant CRMO-associated conditions (e.g., skin lesions or inflammatory bowel disease). In the latter group, a presumptive diagnosis can be made on imaging with a reasonably high level of confidence, obviating the need for a bone biopsy. One must keep in mind that in most cases only a specific symptomatic site is imaged at presentation in CRMO, even though concurrent active subclinical sites of inflammation are present in a high proportion of the patients. Once CRMO is suspected, such sites should be actively looked for, even in the absence of symptoms, as multifocal disease is usually required for the diagnosis. Exposure to radiation is an especially sensitive issue in the setting of CRMO, given that “occult” sites of involvement are often present and this disorder has no reliable physical findings or laboratory markers, making it necessary to obtain frequent imaging studies  – which should be ideally radiation-free in order to estimate disease activity and guide the treatment. Radiographs are the first imaging study ordered for most patients – albeit most lesions appear radiographically normal  – usually followed by contrast-­enhanced magnetic resonance imaging (MRI) of the affected sites for additional characterization and staging. Radiographs are widely available and less expensive than other imaging methods, being able to suggest the diagnosis when characteristic lesions are present (Figs. 6.1a and 6.2a), but are fairly insensitive in early-stage disease – with a high false-negative rate – and involve exposure to ionizing radia-

tion. On computed tomography (CT), radiographic findings such as lytic lesions, sclerosis, periostitis, hyperostosis, and bone expansion are all well demonstrated (Figs.  6.1b, c, 6.2b, and 6.3a), and this imaging method is also useful to guide bone biopsies; nonetheless, CT is not helpful in the assessment of disease activity, and it also involves exposure of the immature organism to radiation. Whole-body bone scintigraphy with Technetium-99m is valuable in the investigation of additional skeletal lesions when whole-body MRI is not available, even though bone scans are not as sensitive as MRI in this setting and do not allow any additional characterization of the lesions; furthermore, it may be difficult to distinguish inflammation from the physiologic increased uptake at the growth plates, and, once more, there is the issue of radiation exposure (Fig. 6.3). PET-CT has been described as useful to identify active sites of inflammation, which appear as areas of increased uptake, but it delivers even more radiation than the aforementioned imaging methods. For all the exposed above, MRI is currently the imaging modality of choice in CRMO because it is radiation-free and has high sensitivity in demonstrating (1) the presence and extent of inflammatory changes in the bones and in the soft tissues, (2) arthritis (which is present in a non-negligible fraction of the affected patients), and (3) complications such as bone deformities, physeal bars, and fractures, being also useful (4) in the monitoring of disease activity and response to treatment in serial studies (Figs. 6.1d, e, 6.2c, d, 6.3, and 6.4). Active lesions are typically associated with bone marrow edema and post-gadolinium enhancement (Figs.  6.1, 6.2, 6.3, and 6.4), while inactive chronic lesions exhibit predominance of sclerosis, with low signal intensity in all sequences and absent enhancement. Even though inflammation of the surrounding soft tissues may also be found, sequestra, abscesses, and skin fistulae are typically absent. Bilateral and symmetric disease is not uncommon, so that adding one or more fluid-sensitive MRI sequences with an increased field-of-view in selected cases in order to demonstrate concurrent involvement of the contralateral limb is frequently rewarding in the authors’ experience (Fig. 6.4). Once “typical” lesions are found, whole-body MRI has a vital role in the management of patients with CRMO, both to detect additional – and frequently “silent” – sites of osteitis and to monitor disease activity and treatment response in long-term surveillance. In addition to coronal whole-body STIR images, a targeted sagittal STIR sequence of the whole spine is also acquired. Key sites to look for lesions on whole-­body MRI include the pelvis, femora, tibiae, ankles, feet, spine, clavicles, sternum, and ribs. High ADC values are found in CRMO lesions on diffusion-weighted images and are useful in distinguishing them from malignant lesions, as lower ADC values are found in tumors. As neither imaging nor biopsy can provide a specific diagnosis, there is a growing trend toward the use of whole-body MRI in difficult cases.

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a

c

b Fig. 6.1  An 11-year-old female with CRMO involving both knees and the right ankle. Anteroposterior radiograph (a) and reformatted coronal CT images (b) of the knees disclose several well-delimited lytic lesions in the distal metaphyses of the femora and in the proximal metaphyses of the tibiae, adjacent to the growth plates, surrounded by extensive bone sclerosis. The abnormalities are more pronounced in the left knee, where increased size of the epiphyses is also present, as well as a lytic lesion associated with marked sclerosis in the proximal tibial epiphysis. In (c), in addition to metaphyseal lytic lesions surrounded by bone sclerosis, reformatted sagittal CT images of the right ankle reveal a

solid periosteal reaction along the posterior cortex of the distal tibia. In (d) and (e), coronal fat sat T2-WI (upper images) and post-gadolinium fat sat T1-WI (lower images) show disease progression over a period of 7 months: bone marrow edema in (e) is much more extensive than it appeared in (d), especially in the right knee, as well as gadolinium enhancement, which is more evident in the lytic lesions than in the edematous bone. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)

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d Fig. 6.1 (continued)

6.2 Chronic Recurrent Multifocal Osteomyelitis

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e Fig. 6.1 (continued)

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a

b

Fig. 6.2  Radiographs of both knees (a) and reformatted coronal and sagittal CT images of the right knee (b) of a 12-year-old female with CRMO show symmetric and bilateral involvement of the metaphyses of the femora, tibiae, and fibulae; clustered lytic lesions surrounded by sclerosis can be seen adjoining the growth plates in all involved bones with the exception of the left fibula, where only sclerosis is present. The sclerotic component is much less important than that seen in 6.1.

In (c) and (d), coronal and sagittal fat sat PD-WI of the right knee of a different patient (12-year-old girl) acquired 6  months apart disclose reactivation of previously quiescent CRMO: the upper images reveal only minimal juxtaphyseal bone marrow edema, more evident in the distal femur, while the lower images show worsening of the edematous changes and the appearance of small hyperintense metaphyseal nodules that were previously absent (circled areas)

6.2 Chronic Recurrent Multifocal Osteomyelitis

c

d

Fig. 6.2 (continued)

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a

b

Fig. 6.3  Axial CT image (a, left), sagittal T1-WI (a, center), and fat sat PD-WI (a, right) of the left hip of a 12-year-old female with CRMO displaying lytic lesions in the proximal metaphysis of the femur, with extensive bone marrow edema extending to the proximal diaphysis and moderate joint effusion; mild bone sclerosis surrounding the lesions is

present in the CT image. In (b), in addition to increased uptake in the left hip, a bone scintigraphy reveals abnormal focal uptake adjoining the distal growth plate of the left femur, which corresponds to another focus of osteitis. The physiological uptake in the growth plates makes areas of abnormal bone activity harder to identify

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a

b

Fig. 6.4  A 9-year-old female with CRMO. In (a), sagittal fat sat PD-WI (left) and T1-WI (right) of the right ankle disclose juxtaphyseal metaphyseal lesions surrounded by bone marrow edema in the distal tibia and fibula, with subtle edema of the adjacent soft tissues; bone marrow edema is also present in the epiphysis. In (b), additional coronal fat sat PD-WI

with increased field-of-view performed ad hoc reveal similar findings in the contralateral tibia and fibula. In (c), sagittal fat sat PD-WI (left) and post-gadolinium fat sat T1-WI (right) reveal inflammatory involvement of the right calcaneal apophysis of the same child, with enhancement of the edematous changes of the bone and adjacent soft tissues

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c

Fig. 6.4 (continued)

Despite its advantages, MRI availability may be limited (especially regarding whole-body MRI, mostly in limitedresource countries), and it often requires sedation in young children.

6.2.3 Affected Sites As stated above, the metaphyses of the long bones are the most common sites of involvement in CRMO (up to 3/4 of all cases), and the distal metaphysis of the tibia is the most commonly affected site. The radiographic picture is dominated by osteitis (inflammation of the cancellous bone in the medullary cavity), which leads to varied degrees of osteolysis and osteosclerosis, and the most common appearance on radiographs and CT is that of sclerosis with intervening areas of lucency (Figs. 6.1, 6.2, 6.3, and 6.5). In addition, juxtaphyseal round lucent lesions are commonly found abutting the growth plate, which may be solitary or multiple, surrounded by peripheral sclerosis that becomes progressively thicker and may eventually become the dominant component (Figs. 6.1, 6.2, 6.3, and 6.5); physeal widening may be present as well (Fig.  6.6). Periosteal reaction is not infrequent and is usually more prominent in small-thickness bones such as the fibula, metacarpals, and metatarsals (Figs. 6.1 and 6.7). Late radiographic findings include hyperostosis (cortical thickening and narrowing of the medullary canal) and abnor-

mal bone modeling, with bone expansion, metaphyseal widening, and diaphyseal involvement in long-standing disease (Fig. 6.8). Osteitis-related bone marrow edema is the earliest finding on MRI, which is present before radiographic changes become apparent; the above described juxtaphyseal lesions (which present low-to-intermediate signal intensity on T1-WI and high signal intensity on fluid-sensitive sequences) and periostitis are also present on MRI, as well as edema of the adjacent soft tissues (Figs.  6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, and 6.9); as stated above, bone sclerosis displays low signal intensity in all sequences. Even though rare, diaphyseal-metaphyseal, metaphyseal-epiphyseal, and purely diaphyseal lesions may be found (Fig. 6.7). In ­addition to bone deformities (Fig.  6.10), complications of CRMO described in the literature include bone demineralization, fractures (Fig. 6.11), physeal bars and/or growth arrest, asymmetric growth, limb-length discrepancy, and joint dislocation. The presence of transphyseal involvement must be mentioned in the reports as it may indicate patients at higher risk for the formation of physeal bars (Figs. 6.1, 6.4, 6.5, 6.7, and 6.9). Clavicular involvement occurs in 20–40% of all cases and presents clinically as a painful mass typically located in the medial third of this bone, which may be initially misinterpreted as infection or tumor. Nonetheless, one must remember that the clavicle is an uncommon site of bacterial osteomyelitis. Moreover, in spite of its relative rarity, CRMO is the most common non-neoplastic lesion of the clavicle in

6.2 Chronic Recurrent Multifocal Osteomyelitis

165

a

Fig. 6.5  Imaging studies of the right ankle of a 12-year-old male with CRMO. In (a), radiographs show several juxtaphyseal lucent areas in the distal metaphyses of the tibia and fibula. In (b), MRI images acquired in different planes and sequences reveal, in addition to the

lesions described on radiographs, similar lesions abutting the physis of the calcaneal apophysis, as well as extensive surrounding bone marrow edema (which is also present in the epiphyses) and inflammation of the adjacent soft tissues

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b Fig. 6.5 (continued)

Fig. 6.6  Radiographs of the left knee of a child with CRMO. There is extensive bone sclerosis in the metaphyses of the distal femur and proximal tibia, more pronounced in the latter, in which there are confluent juxtaphyseal erosions and widening of the adjacent growth plate. (Courtesy of Dr. Marcelo Ricardo Canuto Natal, MD, Sabin Medicina Diagnóstica and Hospital de Base do Distrito Federal, Brasília, Brazil)

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a

Fig. 6.7  An 11-year-old female with CRMO. In (a), axial T1-WI (left), fat sat T2-WI (center), and post-gadolinium fat sat T1-WI (right) of the left foot disclose diaphyseal thickening and circumferential periosteal reaction related to the second metatarsal bone, with edema of the bone marrow and of the adjacent soft tissues, involvement of the distal

physis, and marked post-gadolinium enhancement. Additional lesions are present adjoining the physis of the greater trochanter (b) and (c), with associated bone marrow edema and inflammation of the adjacent soft tissues

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b

Fig. 6.7 (continued)

the first two decades of life, being also the most common primary lesion of the medial third of this bone across all age groups. Therefore, an expansile lesion affecting the medial clavicle and sparing the sternoclavicular joint in children and adolescents should be considered CRMO until proven otherwise. The typical presentation on imaging studies is that of a osteolytic expansile lesion involving the medial extremity of the clavicle that may closely resemble an aggressive process,

with periosteal reaction (frequently of the “onion skin” type) and associated soft-tissue component (Figs. 6.12 and 6.13). Unlike in SAPHO syndrome, the sternoclavicular joint, the anterior portion of the ribs, and the adjacent manubrium are typically spared, and there are no signs of sternoclavicular arthritis or costoclavicular enthesopathy. Radiographic assessment of this anatomically complex region is notoriously difficult because of superposition of bone structures

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169

c

Fig. 6.7 (continued)

(Fig. 6.12). Thus, despite the fact that computed tomography (CT) is not usually ranked among the first-line imaging methods for evaluation of CRMO, the authors find contrast-­ enhanced CT particularly useful in the initial assessment of clavicular lesions because of its multiplanar capabilities and exquisite anatomic detail, providing an accurate depiction of the lesion itself (notably the components of sclerosis, osteolysis, and hyperostosis and the periosteal reaction) and the relations with the surrounding intrathoracic structures (Figs. 6.12 and 6.13). MRI has the added benefits of demonstrating active osteitis and evaluating the soft-tissue component more properly (Fig. 6.12). As mentioned above, some authors believe that isolated involvement of the clavicle, when typical, has the same meaning of multifocal involvement as a diagnostic criterion for CRMO. The pelvic bones are involved in as much as 20% of all cases of CRMO, mostly adjoining the metaphyseal equivalents (such as the apophyseal physes, the sacroiliac joints, the ischiopubic synchondrosis, and the triradiate cartilage). As for the above described sites, findings include osteolytic lesions, periosteal reaction, and sclerosis, with osteitis, peri-

ostitis, and edema of the adjacent soft tissues in active lesions (Figs. 6.14 and 6.15). Lesions of the triradiate cartilage are frequently associated with hip effusion and may closely resemble bacterial osteomyelitis and septic arthritis (Fig. 6.15). If a single joint is being examined (such as the hip or the sacroiliacs) and findings are indicative of CRMO, the authors have found useful in their practice to include axial and/or coronal fluid-sensitive sequences of the whole pelvis in order to reveal clinically silent sites of involvement that are often present and might otherwise go unnoticed (Fig. 6.14). Involvement of the spine varies largely between different series, ranging from 3% to 34%, but most authors mention something in the range of 20%. The thoracic spine is more affected than the lumbar segment, and cervical involvement is rare. It is noteworthy that the vertebral bodies are the most common site of pathologic fractures in CRMO, mainly in the thoracic vertebrae, which may be the cause of scoliosis of acute onset. The typical lesion is osteolytic and affects the vertebral body, with varied degrees of sclerosis, and may extend to the pedicles and to the adjacent soft tissues; vertebral collapse is a common

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Fig. 6.8  In (a), chronic inflammation of the left proximal radius related to long-standing CRMO in a 10-year-old boy led to physeal widening of the proximal radius, irregular contours of the adjacent metaphysis and epiphysis, and flaring of the proximal metadiaphysis; there is also a multilayered periosteal reaction, as well as bone sclerosis mixed with lucent areas. In (b), long-standing CRMO of the proximal tibia in another child led to hyperostosis, with cortical thickening and narrowing of the medullary canal; heterogeneous bone sclerosis is also present, with intervening lucent areas

a

b

6.3 DIRA and Majeed Syndrome

171

a

Fig. 6.9  An 11-year-old female with CRMO. In (a) and (b), reformatted CT images show lytic lesions abutting the growth plate of both fibulae, with surrounding sclerosis. In (c), MRI images of the right ankle reveal bone marrow edema adjoining the aforementioned lesions, with transphyseal involvement. In (d), coronal and sagittal PD-WI of the

finding, which may have the appearance of vertebra plana, without reconstitution of the vertebral height after healing (Fig.  6.16). There may be involvement of more than one vertebra, either contiguous or noncontiguous, typically without disc involvement or abscess development (Fig.  6.16). Involvement of the costovertebral joints may occur as well, with osteolysis, periostitis, and occasional widening of the posterior portion of the rib, in addition to edema of the adjacent soft tissues (Fig. 6.17). The mandible is affected in approximately 5–10% of all patients, with a high percentage of deforming changes on long-term follow-up. Imaging findings are similar to those abovementioned, with lytic changes associated with varied degrees of sclerosis in early disease and increasing sclerosis with hyperostosis and progressive enlargement of the mandible as the disease advances. Inflammation of the soft tissues may be present as well.

right knee of the same child disclose juxtaphyseal lytic lesions in the distal femur and proximal tibia, surrounded by extensive bone marrow edema extending to the adjacent epiphyses and associated with inflammation of the contiguous soft tissues (note the presence of fluid within the deep infrapatellar bursa)

6.3

DIRA and Majeed Syndrome

Deficiency of interleukin-1 receptor antagonist (DIRA) and Majeed syndrome are both autoinflammatory bone diseases that occur in early life in which sterile osteomyelitis is a prominent component, but present distinct clinical features. DIRA is a newly recognized autosomal recessive disorder that appears as sterile multifocal osteomyelitis, periostitis, pustulosis, and systemic inflammation of neonatal onset, whose clinical symptoms start in the first weeks after birth. Even though osteitis and periostitis may involve any skeletal site, the long bones (with a predilection for the proximal femur), ribs, clavicles, and spine (vertebral bodies) are affected most often. Osteitis is usually severe, with extensive bone involvement and prominent periostitis, and widened ribs with periosteal changes are a constant finding. Spinal mani-

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b

c

Fig. 6.9 (continued)

6.3 DIRA and Majeed Syndrome

d

Fig. 6.9 (continued) Fig. 6.10  A 13-year-old girl with CRMO since age 8. The patient’s guardians opted to abandon the pharmacologic treatment, and the child remained drug-free for almost 5 years, evolving with progressive genu varum and receiving only orthopedic support. A panoramic radiograph of the lower limbs shows severe genu varum with bilateral epiphysiodesis of the distal femora. Note the typical juxtaphyseal lytic lesions in the long bones of both lower limbs

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Fig. 6.11  A 9-year-old male with CRMO and spontaneous patellar fracture. Sagittal fat sat PD-WI (left) and T1-WI (right) disclose an incomplete transversal fracture involving the cancellous bone of the anteriormost portion of the upper third of the patella, surrounded by bone marrow edema

a

Fig. 6.12 Clavicular involvement in a 14-year-old male with CRMO.  In (a), anteroposterior radiographs reveal widening of the medial third of the right clavicle, with mixed lytic and/or sclerotic appearance of the bone and soft-tissue swelling. In (b), axial fat sat T2-WI (left) and post-gadolinium fat sat T1-WI (right) disclose edematous changes of the clavicular bone and of the adjacent soft tissues,

which show enhancement on post-contrast images, mainly in the affected bone. In (c), oblique reformatted CT images of the right clavicle show in high detail destruction of the medial third of the bone along with bone expansion and extensive periosteal reaction, as well as mild sclerosis of the cancellous bone

6.3 DIRA and Majeed Syndrome

b

c

Fig. 6.12 (continued)

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a

b

c

Fig. 6.13  A 16-year-old male with CRMO and involvement of the left clavicle. Reformatted coronal CT image of the anterior chest wall (a) shows a destructive lesion in the medial third of the left clavicle with adjacent soft-tissue component. In (b), oblique reformatted CT images of the right (upper image) and left (lower image) clavicles display destruction and fragmentation of the medial extremity of the latter, with

marked periosteal reaction and soft-tissue swelling. Comparative reformatted axial oblique CT images (c) reveal, in addition to the above described destructive lesion, sclerosis of the cancellous bone and diffuse hyperostosis of the left clavicle, with cortical thickening and narrowing of the medullary canal

6.3 DIRA and Majeed Syndrome

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a

b

Fig. 6.14  A 9-year-old female with CRMO and pelvic lesions. In (a), axial T1-WI and fat sat T2-WI demonstrate small lytic lesions of the cancellous bone, bone marrow edema, and soft-tissue edema adjacent to the right ischiopubic synchondrosis. A supplementary coronal fat sat T2-weighted sequence with increased field-of-view including the whole

pelvis (b) was subsequently performed and disclosed multiple sites of bone marrow edema affecting the symphysis pubis, the triradiate cartilages, both ischiopubic synchondroses, the iliac crest apophyses (notably in the left side), and the sacroiliac joints

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a

b

Fig. 6.15  Axial (a) and coronal (b) fat sat T2-WI of the left hip exhibit multifocal involvement of the pelvis in a 10-year-old boy with CRMO. In addition to osteitis, lytic lesions, and soft-tissue edema adjacent to the right ischiopubic synchondrosis, there is also involvement of

the left triradiate cartilage, associated with hip effusion and edema of the adjacent obturator internus muscle, mimicking osteomyelitis and septic arthritis

festations include vertebral collapse with secondary fusion of vertebral bodies (Fig. 6.18) and vertebral instability, the latter mostly seen in the upper cervical spine. Less common findings include heterotopic ossification of the proximal femora, clavicular widening, and lytic calvarial lesions. Majeed syndrome, on its turn, presents as sterile multifocal osteomyelitis with onset in the first 2 years of life and is typically associated with congenital dyserythropoietic anemia. Although it may resemble CRMO, Majeed syndrome is an inherited autosomal recessive disease that, in addition to the unique association with dyserythropoietic anemia, has an earlier age of onset and follows a more severe clinical course. The most affected sites in Majeed syndrome are similar to those above described for CRMO, with preferential involvement of the metaphyses of long bones.

of the anterior chest wall (even though it may involve any skeletal segment) and dermatological abnormalities such as palmoplantar pustulosis and severe acne. SAPHO can affect patients of any age group and its etiology is still unknown. Children with SAPHO syndrome usually have a chronic disease that intercalates periods of exacerbation and remission. Cutaneous and osteoarticular manifestations do not necessarily appear simultaneously, and skin involvement in pediatric patients is not as frequent as in adults. Prognosis is overall good and disabling complications are rare. Osteoarticular manifestations include osteitis, hyperostosis, synovitis, arthritis, and enthesitis, usually of insidious onset, which are often accompanied by pain, tenderness, swelling, phlogosis, and limited range of motion in the affected sites. Systemic manifestations are uncommon and, when present, usually of mild intensity. While the anterior chest wall (mostly the sternoclavicular region) is the most affected site in adolescents, there is a predominance in the long bones in pediatriconset SAPHO (metadiaphyses are most affected, especially the distal femur and proximal and distal tibia). Spinal involvement seems to be not uncommon, with a tendency to affect the anterior vertebral body corners, and other sites are reported with highly variable frequency. Arthritis is a frequent finding, usu-

6.4

SAPHO Syndrome

The acronym SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) identifies a clinical syndrome that encompasses a variety of chronic and recurrent osteoarticular manifestations, mostly osteitis and hyperostosis of the bones

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6.5 NOMID and/or CINCA

Fig. 6.16  Lateral radiograph (left), sagittal T2-WI (center), and sagittal post-gadolinium fat sat T1-WI (right) of the thoracic spine of a 10-year-old male with CRMO. Radiographic findings include collapse and sclerosis of a midthoracic vertebral body (vertebra plana) with no apparent abnormalities of the adjacent vertebrae. On MRI images, in

addition to the aforementioned vertebral collapse, there are bone marrow edema in the adjacent vertebrae and infiltration of the prevertebral and posterior epidural soft tissues, all of which show post-contrast enhancement. The contiguous intervertebral discs, however, show no signs of inflammation

ally affecting the joints adjacent to the involved bones, both in children and in adults; the sternoclavicular and sternocostal joints are affected most often, followed by knees, hips, ankles, and, less commonly, the small joints of the hands and feet. Enthesopathy may lead to ossification of the ligaments and, ultimately, development of bone bridging across affected joints. Radiographs are fairly insensitive in early disease; initial lesions are often lytic, with or without surrounding sclerosis, typically accompanied by endosteal or periosteal reaction. With disease progression, a mixed lytic and/or sclerotic appearance of the bone ensues, and later findings include diffuse sclerosis, hyperostosis, thick periostitis, and ligament ossification. When arthritis is present, there may be erosions and joint space narrowing. Spinal involvement includes lesions of the vertebral body corner (similar to those seen with Romanus lesions in spondyloarthritis, with bone marrow edema followed by fatty replacement [on MRI] and sclerosis and/or erosions), non-specific spondylo-

discitis, and destructive bone lesions; sacroiliitis, however, is usually seen only in the subgroup of adult patients. Just like in CRMO, MRI is the imaging method of choice to detect early subclinical lesions and to monitor the evolution of edematous changes of the bone marrow (osteitis), which are indicative of disease activity, being also useful to identify inflammation of the adjacent soft tissues. Once again, just like in CRMO, wholebody bone scintigraphy and whole-­body MRI are both able to detect clinically silent sites of involvement; the latter is preferable in children as it does not involve exposure to radiation.

6.5

NOMID and/or CINCA

Neonatal-onset multisystem inflammatory disease (NOMID), also called chronic infantile neurological cutaneous and articular (CINCA) syndrome, is a genetic dis-

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Fig. 6.17  Involvement of the left costovertebral joint at level T7 in a 9-year-old boy with CRMO. The left images display axial STIR slices showing osteitis in the posterior portion of the corresponding rib and adjacent soft-tissue edema. The right images display transverse and

reformatted coronal CT images disclosing predominantly lytic changes of the medullary bone, as well as cortical destruction and mild expansion of the posterior extremity of the rib

ease included in the group of the cryopyrin-associated periodic syndromes. It is a chronic autoinflammatory disorder characterized by the triad of skin rash, arthropathy (related to bone overgrowth), and central nervous system abnormalities. While nearly two-thirds of patients have only arthralgia or transient arthritis, in a third part there is a deforming arthropathy with overgrowth of the patella and of the epiphyses of the long bones. The articular manifestations are the most remarkable and characteristic features of the disease, with symmetric or asymmetric involvement of peripheral joints, notably the knees, followed by ankles, midfoot, elbows, wrists, and hands. Enlargement of the non-ossified portion of the physis is the earliest finding, related to abnormal endochondral bone formation leading to the appearance of large and heterogeneously calcified masses (mostly the distal physis of the femur and the

proximal physis of the tibia). These masses cause deformation of the adjacent epiphyses and metaphyses (which appear splayed and cupped, with irregular contours) and bone overgrowth, with no evidence of synovial thickening or bone erosions. The lesions are initially not mineralized but customarily become calcified on serial radiographs as the patient grows. Patellar overgrowth with irregular borders and heterogeneous ossification is the most characteristic radiographic finding in patients with NOMID and/or CINCA.  Secondary osteoarthritis has been frequently reported in patients with bone changes. Other abnormalities include osteoporosis, delayed bone age, genu varus and/or valgus, limb-length discrepancy, and short stature (the latter three related to early closure of the growth plates). On MRI, the physeal masses present low signal intensity on T1-WI and intermediate signal on T2-WI, with post-gadolinium enhancement.

Recommended Reading

Fig. 6.18  A 4-year-old female with DIRA.  Reformatted sagittal CT images reveal extensive bone destruction and collapse of several upper thoracic vertebral bodies related to long-standing osteitis, with severe

Key Points

• Autoinflammatory bone diseases are characterized by chronic osteitis, inflammation-induced bone resorption, and bone remodeling. Chronic recurrent multifocal osteomyelitis (CRMO), SAPHO syndrome, Majeed syndrome, pyoderma gangrenosum and acne (PAPA), deficiency of interleukin-1 receptor antagonist (DIRA), CINCA and/or NOMID, and cherubism are among the most common pediatric disorders in this group, and CRMO is by far the most studied and well-recognized of them all. • In patients with CRMO and classic imaging findings, a presumptive diagnosis can be made with a reasonably high level of confidence, obviating the need for a bone biopsy. • Varied degrees of osteolysis and/or osteosclerosis, periostitis, hyperostosis, and bone expansion can be found in CRMO, and the metaphyses of the long bones are the most common sites of involvement. MRI is the imaging modality of choice as it demonstrates inflammatory changes in the bones and in the soft tissues and allows adequate monitoring of disease activity and response to treatment.

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disorganization of the spinal architecture. Fusion of the corresponding apophyseal joints was also present (not shown)

• Whole-body bone scintigraphy and whole-body MRI are both useful to characterize multifocal CRMO and to monitor disease activity and treatment response, the latter being the preferred imaging method in long-term surveillance.

Recommended Reading 1. Aksentijevich I, Masters SL, Ferguson PJ, Dancey P, Frenkel J, van Royen-Kerkhoff A, et  al. An autoinflammatory disease with deficiency of the interleukin-1-receptor antagonist. N Engl J Med. 2009;360:2426–37. 2. Berkowitz YJ, Greenwood SJ, Cribb G, Davies K, Cassar-Pullicino VN.  Complete resolution and remodeling of chronic recurrent multifocal osteomyelitis on MRI and radiographs. Skeletal Radiol. 2018;47:563–8. 3. Chen HC, Wuerdeman MF, Chang JH, Nieves-Robbins NM. The role of whole-body magnetic resonance imaging in diagnosing chronic recurrent multifocal osteomyelitis. Radiol Case Rep. 2018;13:485–9. 4. Costa-Reis P, Sullivan KE. Chronic recurrent multifocal osteomyelitis. J Clin Immunol. 2013;33:1043–56. 5. Falip C, Alison M, Boutry N, Job-Deslandre C, Cotten A, Azoulay R, et al. Chronic recurrent multifocal osteomyelitis (CRMO): a longitudinal case series review. Pediatr Radiol. 2013;43:355–75.

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6  Imaging of Chronic Recurrent Multifocal Osteomyelitis and Autoinflammatory Bone Disorders

6. Greenwood S, Leone A, Cassar-Pullicino VN. SAPHO and recurrent multifocal osteomyelitis. Radiol Clin North Am. 2017;55:1035–53. 7. Greer MC.  Whole-body magnetic resonance imaging: techniques and non-oncologic indications. Pediatr Radiol. 2018;48:1348–63. 8. Hedrich CM, Hofmann SR, Pablik J, Morbach H, Girschick HJ. Autoinflammatory bone disorders with special focus on chronic recurrent multifocal osteomyelitis (CRMO). Pediatr Rheumatol Online J. 2013; https://doi.org/10.1186/1546-0096-11-47. 9. Hill SC, Namde M, Dwyer A, Poznanski A, Canna S, Goldbach-­ Mansky R. Arthropathy of neonatal onset multisystem inflammatory disease (NOMID/CINCA). Pediatr Radiol. 2007;37:145–52. 10. Jurik AG, Klicman RF, Simoni P, Robinson P, Teh J.  SAPHO and CRMO: the value of imaging. Semin Musculoskelet Radiol. 2018;22:207–24. 11. Khanna G, Sato TS, Ferguson P. Imaging of chronic recurrent multifocal osteomyelitis. Radiographics. 2009;29:1159–77. 12. Koplas MC, Simonelli PS, Bauer TW, Joyce MJ, Sundaram M. Your diagnosis? chronic recurrent multifocal osteomyelitis. Orthopedics. 2010;33:218. 13. Leclair N, Thörmer G, Sorge I, Ritter L, Schuster V, Hirsch FW. Whole-body diffusion-weighted imaging in chronic recurrent multifocal osteomyelitis in children. PLoS One. 2016; https://doi. org/10.1371/journal.pone.0147523. 14. Mallick A, Chaturvedi A, Muthukumar N. Chronic recurrent multifocal osteomyelitis: a diagnostic dilemma: a case report and review of the literature. JBJS Case Connect. 2016; https://doi.org/10.2106/ JBJS.CC.15.00119. 15. Modesto C.  Síndrome CINCA/NOMID.  Med Clin (Barc). 2011;136(Suppl 1):10–5. 16. Morbach H, Hedrich CM, Beer M, Girschick HJ. Autoinflammatory bone disorders. Clin Immunol. 2013;147:185–96. 17. Nguyen MT, Borchers A, Selmi C, Naguwa SM, Cheema G, Gershwin ME.  The SAPHO syndrome. Semin Arthritis Rheum. 2012;42:254–65. 18. Queiroz RM, Rocha PHP, Lauar LZ, Costa MJBD, Laguna CB, Oliveira RGG.  Chronic recurrent multifocal osteomyelitis exhibiting predominance of periosteal reaction. Rev Assoc Med Bras. 1992;63:303–6.

19. Roderick MR, Shah R, Rogers V, Finn A, Ramanan AV.  Chronic recurrent multifocal osteomyelitis (CRMO) – advancing the diagnosis. Pediatr Rheumatol Online J. 2016; https://doi.org/10.1186/ s12969-016-0109-1. 20. Roderick MR, Sen ES, Ramanan AV.  Chronic recurrent multifocal osteomyelitis in children and adults: current understanding and areas for development. Rheumatology (Oxford). 2018;57:41–8. 21. Rukavina I.  SAPHO syndrome: a review. J Child Orthop. 2015;9:19–27. 22. Sirisha K, Keerthi T, Habibi S, Varaprasad IR, Jyotsna Rani Y, Narendranath L, et  al. Chronic recurrent multifocal osteomyelitis complicated by hip subluxation: a case report. Int J Rheum Dis. 2017;20:1800–1. 23. Stern SM, Ferguson PJ. Autoinflammatory bone diseases. Rheum Dis Clin North Am. 2013;39:735–49. 24. Surendra G, Shetty U. Chronic recurrent multifocal osteomyelitis: a rare entity. J Med Imaging Radiat Oncol. 2015;59:436–44. 25. Thacker PG, Binkovitz LA, Thomas KB. Deficiency of interleukin-­ 1-­receptor antagonist syndrome: a rare auto-inflammatory condition that mimics multiple classic radiographic findings. Pediatr Radiol. 2012;42:495–8. 26. Vargas Pérez M, Sevilla Pérez B. SAPHO syndrome in childhood. A case report. Reumatol Clin 2018;14:109–12. 27. Voit AM, Arnoldi AP, Douis H, Bleisteiner F, Jansson MK, Reiser MF, et  al. Whole-body magnetic resonance imaging in chronic recurrent multifocal osteomyelitis: clinical longterm assessment may underestimate activity. J Rheumatol. 2015;42:1455–62. 28. von Kalle T, Heim N, Hospach T, Langendörfer M, Winkler P, Stuber T.  Typical patterns of bone involvement in whole-body MRI of patients with chronic recurrent multifocal osteomyelitis (CRMO). Rofo. 2013;185:655–61. 29. Zaki FM, Sridharan R, Pei TS, Ibrahim S, Ping TS. NOMID: the radiographic and MRI features and review of literature. J Radiol Case Rep. 2012;6:1–8. 30. Zhao Y, Ferguson PJ.  Chronic nonbacterial osteomyelitis and chronic recurrent multifocal osteomyelitis in children. Pediatr Clin North Am. 2018;65:783–800.

7

Imaging of Articular and Periarticular Tumors and Pseudotumors

7.1

Introduction

Even though tumors and pseudotumors are not rheumatic conditions per se, their clinical and/or imaging presentation often resemble those of articular diseases, especially when located within the joints or in nearby areas. Histopathological analysis remains indispensable for a definitive diagnosis, but imaging studies play a fundamental role in the assessment of these lesions. Many musculoskeletal tumors and/or pseudotumors display a typical appearance on imaging, thus allowing a presumptive diagnosis with a reasonable degree of accuracy. In addition, surgical planning relies on adequate preoperative staging, which can be safely achieved with imaging. Only selected lesions more prone to simulate rheumatic conditions in the pediatric age group – either from a clinical standpoint or on imaging – are covered in this chapter. Bone lesions include osteoid osteoma, chondroblastoma, cortical desmoids, focal fibrocartilaginous dysplasia, and dysplasia epiphysealis hemimelica, while pigmented villonodular synovitis, localized nodular synovitis, giant cell tumor of the tendon sheath, lipoma arborescens, primary synovial osteochondromatosis, and synovial hemangioma comprise the soft-tissue lesions to be studied.

7.2

Bone Lesions

Two primary bone tumors of the childhood will deserve special attention in this topic: osteoid osteoma (OO) and chondroblastoma. OO is the most common of the benign bone tumors, usually found in males in the second decade of life. It is a small (