Nuclear Medicine and PET/CT Cases (Cases in Radiology) [1 ed.] 9780199773695, 2014046160

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Nuclear Medicine and PET/CT Cases

Published and Forthcoming Books in the Cases in Radiology series: Body MRI Cases, William Brant and Eduard de Lange Breast Imaging Cases, Catherine Appleton and Kimberly Wiele Cardiac Imaging Cases, Charles White and Joseph Jen-Sho Chen Chest Imaging Cases, Sanjeev Bhalla, Cylen Javidan-Nejad, Kristopher W. Cummings, and Andrew Bierhals Emergency Radiology Cases, Hani Abujudeh Gastrointestinal Imaging Cases, Angela Levy, Koenraad Mortele, and Benjamin Yeh Genitourinary Imaging Cases, Mark Lockhart and Rupan Sanyal Interventional Radiology Cases, Anne M. Covey, Bradley Pua, Allison Aguado, and David Madoff Musculoskeletal Imaging Cases, Mark Anderson and Stacy Smith Neuroradiology Cases, Clifford Eskey, Clifford Belden, David Pastel, Arastoo Vossough, and Albert Yoo Nuclear Medicine and PET/CT Cases, Chun Kim Pediatric Imaging Cases, Ellen Chung

Nuclear Medicine and PET/CT Cases Edited by Chun K. Kim Associate Professor of Radiology Harvard Medical School Clinical Director of Nuclear Medicine and Molecular Imaging Brigham and Women’s Hospital Boston, Massachusetts

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1 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford New York Auckland  Cape Town  Dar es Salaam  Hong Kong  Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Oxford is a registered trademark of Oxford University Press in the UK and certain other countries. Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016

© Oxford University Press 2015 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by license, or under terms agreed with the appropriate reproduction rights organization. Inquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. Library of Congress Cataloging-in-Publication Data Nuclear medicine and PET/CT cases / edited by Chun K. Kim. p. ; cm. Includes bibliographical references and index. ISBN 978–0–19–977369–5 (alk. paper) I.  Kim, Chun K., editor.  II.  Title. [DNLM:  1.  Nuclear Medicine—Case Reports.  2.  Diagnosis, Differential—Case Reports.  3.  Radioisotopes—therapeutic use—Case Reports.  4.  Radionuclide Imaging—methods—Case Reports. WN 440] R895 616.07′575—dc23 2014046160 This material is not intended to be, and should not be considered, a substitute for medical or other professional advice. Treatment for the conditions described in this material is highly dependent on the individual circumstances. And, while this material is designed to offer accurate information with respect to the subject matter covered and to be current as of the time it was written, research and knowledge about medical and health issues are constantly evolving and dose schedules for medications are being revised continually, with new side effects recognized and accounted for regularly. Readers must therefore always check the product information and clinical procedures with the most up-to-date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulation. The publisher and the authors make no representations or warranties to readers, express or implied, as to the accuracy or completeness of this material. Without limiting the foregoing, the publisher and the authors make no representations or warranties as to the accuracy or efficacy of the drug dosages mentioned in the material. The authors and the publisher do not accept, and expressly disclaim, any responsibility for any liability, loss, or risk that may be claimed or incurred as a consequence of the use and/or application of any of the contents of this material. 9 8 7 6 5 4 3 2 1 Printed in the United States of America on acid-free paper

To my parents, wife, and children for their love and support. –Chun K. Kim

Acknowledgments

The Publisher thanks the following for their time and advice: Mark Anderson, University of Virginia Sanjeev Bhalla, Mallinckrodt Institute of Radiology, Washington University Michael Bruno, Penn State Hershey Medical Center Melissa Rosado de Christenson, St. Luke’s Hospital of Kansas City Rihan Khan, University of Arizona Angela Levy, Georgetown University Alexander Mamourian, University of Pennsylvania Stacy Smith, Brigham and Women’s Hospital

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Preface

This book presents general nuclear medicine and PET/CT imaging cases in a concise case format. While the book is primarily intended for radiology residents and nuclear medicine residents and fellows, any imagers performing and interpreting nuclear medicine studies will find it useful. The format of this book is unique in that individual cases are presented as unknown cases on the front page, with or without a brief history, along with images without arrows so that the readers can appraise the relevant findings and formulate possible differential considerations before turning over the page that simulates closely the reading room experience. On the top of the second page of each case, the diagnosis or the major point of the case and selected images with arrows pointing out the major findings, if felt to be helpful, are provided. Then, the type of radiopharmaceutical and dose, procedure, major findings, differential diagnosis, teaching points, and management are presented using easy-to-follow bullet points. This book is intended not to offer exhaustive and often impractical discussion on individual cases, such as long lists of differential diagnoses that can be found in a typical “Gamut-type” textbook; only the differentials that are practical and that provoke useful thought processes or that contain valuable teaching points are listed in the Differential Diagnosis section. Many of the cases contain companion cases that augment comprehensive understanding of the particular subject. What is emphasized here is the relevant thought process and rationale that are necessary to arrive at the correct diagnosis, as outlined in the Teaching Points section. Some of the teaching points presented in this book are based on the authors’ experience accumulated over 20–30 years, which the readers will find practical and useful. I believe the readers will find this book easy and fun to read. Most radiology residents, for instance, will be able to finish reading it during their 4-week nuclear medicine rotation block. Most practitioners will find surprising depth of information in such a concise book that will stand them in good stead in the busy reading room. It is hoped that this book will serve as a foundation stone in preparation for board examinations and as a valuable reference guide in the practice.

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Contents

Contributors Part 1.  Nuclear CNS Imaging

xiii 1

Part 2.  Nuclear Inflammation/Infection Imaging

23

Part 3.  Ventilation/Perfusion Lung Scintigraphy

61

Part 4.  Pediatric Nuclear Medicine

89

Part 5.  Nuclear Cardiac Imaging

127

Part 6.  Bone Scintigraphy

157

Part 7.  PET/CT in Oncology I

193

Part 8.  PET/CT in Oncology II

239

Part 9.  General Oncologic Imaging

277

Part  10.  Thyroid and Parathyroid

291

Part  11.  Radionuclide Therapy and Pre-Therapy Evaluation

325

Part  12.  Liver, Spleen, and Biliary Tract

345

Part  13.  Gastrointestinal Tract

371

Part  14.  Renal Scintigraphy

389

Part  15.  Potpourri of Cases

405

Appendix 419 Index of Cases

421

Index

425

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Contributors

Scott Britz-Cunningham, MD, PhD Division of Nuclear Medicine West Roxbury VA Medical Center Assistant Professor of Radiology Harvard Medical School Boston, Massachusetts Marcelo F. Di Carli, MD Professor of Radiology Harvard Medical School Chief, Division of Nuclear Medicine and Molecular Imaging Brigham and Women’s Hospital Boston, Massachusetts Frederick D. Grant, MD Assistant Professor of Radiology Harvard Medical School Boston Children’s Hospital Boston, Massachusetts Sherif Heiba, MD Associate Professor of Radiology Icahn School of Medicine Mount Sinai Medical Center New York, New York Laura L. Horky, MD, PhD Instructor in Radiology Harvard Medical School Brigham and Women’s Hospital Boston, Massachusetts Hyewon Hyun, MD Instructor in Radiology Harvard Medical School Brigham and Women’s Hospital Boston, Massachusetts

Heather A. Jacene, MD Assistant Professor of Radiology Harvard Medical School Dana-Farber Cancer Institute Boston, Massachusetts Phillip J. Koo, MD Assistant Professor of Radiology University of Colorado School of Medicine Aurora, Colorado Christopher J. Palestro, MD Chief of Nuclear Medicine and Molecular Imaging North Shore Long Island Jewish Medical Health System Professor of Radiology Hofstra North Shore–LIJ School of Medicine New Hyde Park, New York Won Jun Park, MD CHF Fellow Department of Cardiology Mount Sinai Beth Israel Hospital New York, New York Balaji Rao, MD Assistant Professor of Radiology Yale University School of Medicine New Haven, Connecticut Christopher G. Sakellis, MD Instructor in Radiology Harvard Medical School Dana-Farber Cancer Institute Boston, Massachusetts

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S. Ted Treves, MD Professor of Radiology Harvard Medical School Boston Children’s Hospital Boston, Massachusetts Daniel F. Worsley, MD Assistant Professor of Radiology University of British Columbia Vancouver General Hospital Vancouver, BC, Canada

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Contributors

Katherine A. Zukotynski, MD Assistant Professor University of Toronto Sunnybrook Health Sciences Centre Toronto, ON, Canada

Part 1

Nuclear CNS Imaging Laura L. Horky, Chun K. Kim

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Case 1 History ▶ A 42-year-old woman with refractory epilepsy and normal brain MRI.

Figure 1.1 

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Case 1  Left Temporal Interictal Seizure Focus

Figure 1.2 

Figure 1.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/5 mCi/PET imaging 1 hour after injection.

Findings ▶ Figure 1.2: Hypometabolism in the left temporal lobe. Differential Diagnosis ▶ With history of epilepsy and a normal MRI, the PET finding is most consistent with a left temporal interictal seizure focus.

Teaching Points ▶ Interictal PET is useful in identifying the seizure focus. ▶ Ictal PET (seizure during FDG uptake period) and ictal SPECT studies (inject tracer within 15–30 seconds of ictal onset) typically reveal hypermetabolism/hyperperfusion at the seizure focus, as seen in a different patient in status epilepticus (Figure 1.3), whereas the interictal study will reveal hypoperfusion/hypometabolism, as in Figure 1.2. ▶ Ictal SPECT study, if properly performed, is more sensitive than interictal PET or interictal SPECT, but this study is more difficult to obtain. Furthermore, a delay in tracer injection (>30 seconds after electroclinical onset) may result in a false localization of the seizure focus. Therefore, some centers prefer interictal PET. ▶ Interictal PET is more sensitive than interictal SPECT. ▶ In temporal lobe epilepsy, MRI may be normal or may demonstrate hippocampal sclerosis. ▶ SPECT and PET studies are useful when surface EEG and MRI do not clearly identify a seizure focus. These studies may guide the surgeon to proceed with resection or further diagnostic procedures such as subdural electrode placement. When interictal PET demonstrates cortical left-right asymmetry of at least 15% (mean SUV), surgical outcomes are more likely to be successful (Theodore et al. 1992).

Management ▶ Findings were correlated with MRI (in this case normal) and EEG. ▶ The information was used to determine that the patient would be a candidate for temporal lobectomy. ▶ The patient subsequently underwent an anterior left temporal lobectomy and was seizure-free for at least 2 years afterward. Surgical pathology revealed mild gliosis.

Further Readings Theodore WH, et al. Temporal lobectomy for uncontrolled seizures: the role of positron emission tomography. Ann Neurol. 1992;32:789–794. Horky L, et al. PET and SPECT in brain tumors and epilepsy. Neurosurg Clin N Am. 2011;22:169–184.

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Case 2 History ▶ A 65-year-old comatose patient after head trauma; CT shows subdural and subarachnoid hemorrhage and transtentorial brain herniation. Ant

Post

LL

RL

Figure 2.1 

Figure 2.2 

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Case 2  Brain Death Flow

Ant

Static

LL

Figure 2.3 

SPECT Ant

Post

RL

Figure 2.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-HMPAO/20 mCi/Dynamic imaging immediately after injection, static planar imaging 20 minutes after injection, and if necessary SPECT imaging.

Findings (Figures 2.1–2.3) ▶ No intracranial activity ▶ Hyperperfusion to the nose (hot nose sign) (arrow) Differential Diagnosis ▶ The scan finding is consistent with brain death. Teaching Points ▶ Perfusion tracers (99mTc-ECD and 99mTc-HMPAO) bind to the brain parenchyma. ▶ Absence of brain activity using these tracers is considered diagnostic of brain death. Activity in any part of the brain contradicts the diagnosis.

▶ If planar images are equivocal, consider obtaining SPECT images, if feasible. ▶ Figure 2.4: Example of case that is not brain dead. ▶ Brain may falsely appear viable if imaging within 6 hours of brain function cessation or if activity is present due to scalp or cerebral bleeding.

▶ If tracers that do not cross the blood-brain barrier (e.g., 99mTc-DTPA) are used, the following findings should be evaluated. However, if HMPAO or ECD is used (which is considered the current standard of care), these are merely ancillary findings and should not be solely used to diagnose brain death. ■ “Trident sign” during the arterial phase (composed of a vertical midline activity in the head extending superiorly, representing the right and left anterior cerebral arteries, and bilateral oblique linear activity extending superolaterally, representing right and left middle cerebral arteries) excludes brain death, if present, as seen in the first 4 frames of the flow phase in Figure 2.4. Images are not clear because perfusion tracer was used in this case, causing rapidly rising background brain uptake. ■ “Hot nose sign” signifies preferential external carotid artery circulation in the absence of internal carotid flow; present in approximately 50% of patients with brain death. ■ Absence of venous sinus activity during the venous phase is suggestive of brain death.

Management ▶ If the findings are consistent with brain death, notify the referring team and place a note in the patient’s chart. ▶ If the findings are incompatible with brain death, the test may be repeated at a later date. Further Readings Donohoe K, et al. SNM Procedure Guideline for Brain Death Scintigraphy. version 1.0, 2003 (www.snm.org/guidelines).

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Case 3 History ▶ A 68-year-old man with bilateral internal carotid artery occlusion and left anterior circulation stroke, documented on carotid ultrasound and MR angiogram. Surgical planning for external to internal carotid artery (EC-IC) bypass. Baseline

Figure 3.1 

Post-Diamox

Figure 3.2 

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Case 3  Left ACA Stroke and MCA Ischemia Baseline

Figure 3.3 

Post-Diamox

Figure 3.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-ECD/20 mCi/SPECT imaging 45 minutes after injection.

Findings ▶ Fixed defect in the left anterior cerebral artery (ACA) territory (thin arrow in Figures 3.3 and 3.4) ▶ Reversible defect in the left middle cerebral artery (MCA) territory, seen only on the post-Diamox image (thick arrow in Figure 3.4).

Differential Diagnosis ▶ The fixed defect is consistent with history of left ACA stroke. ▶ The reversible defect in the left MCA territory is consistent with ischemia with compromised cerebrovascular reserve.

Teaching Points ▶ The goal of the study is to identify patients who will benefit from extracranial-intracranial (EC-IC) bypass or carotid endarterectomy.

▶ Acetazolamide (Diamox) is a carbonic anhydrase inhibitor that increases the cerebral circulation x 4. Patients with compromised cerebral circulation may adapt by autoregulatory vasodilation.

▶ Baseline perfusion may appear normal, but after a vasodilator is given, akin to a “perfusion stress test,” the already compromised vessels are not able to dilate further, while the remainder of the cerebral perfusion increases. Therefore, the compromised area looks hypoperfused in comparison.

Management ▶ Patients with unilateral carotid artery stenosis and healthy cerebrovascular reserve at rest are good candidates for carotid artery bypass surgery. Insufficient cerebrovascular reserve signifies an increased risk to the patient during carotid endarterectomy or EC-IC bypass.

Further Readings Juni J, et al. Procedure Guideline for Brain Perfusion SPECT Using 99mTc Radiopharmaceuticals, version 3.0, approved 2009 (http://www.snm.org/guidelines). Vorstrup S, et al. Evaluation of the cerebral vasodilatory capacity by the acetazolamide test before EC-IC bypass surgery in patients with occlusion of the internal carotid artery. Stroke. 1986;17:1291–1298.

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Case 4 History ▶ A 73-year-old woman with dementia.

Figure 4.1 

Figure 4.2 

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Case 4  Alzheimer Disease (AD)

Figure 4.3  Radiopharmaceutical/Dose/Procedure:

Figure 4.4  18F-FDG/10

mCi/PET imaging/1 hour after injection.

Findings (Figures 4.1–4.3) ▶ Hypometabolism of bilateral frontal (mild), parietal, temporal and posterior cingulate cortices ▶ Preserved metabolism of bilateral sensorimotor cortex, deep nuclei, occipital cortex, and cerebellum ▶ Widened interhemispheric, intercaudate, and interthalamic distances, compatible with atrophy. Differential Diagnosis ▶ Parkinson’s dementia: Similar findings to AD, but visual cortex is more affected, and mesial temporal cortex is relatively spared.

▶ In dementia with Lewy bodies (DLB), the occipital cortex is also hypometabolic, in addition to the frontal

and temporoparietal cortex. Additionally, DLB would be the presiding diagnosis if, in addition to cognitive decline, the patient clinically had parkinsonian symptoms and hallucinations, an indicator of pathology in the visual cortex.

Teaching Points ▶ In AD, the initial finding on FDG-PET is temporoparietal hypometabolism; it may be asymmetric at first.

Posterior cingulate hypometabolism is often an early finding as well. In advanced disease, the frontal cortex becomes hypometabolic. The sensorimotor, occipital, and cerebellar cortices are spared in AD. ▶ SPECT imaging with perfusion tracers such as Tc-99m HMPAO or ECD may also be used to determine these diagnoses, but the resolution of PET is superior. ▶ Figure 4.4: (Left) Example of early AD with asymmetric onset in the parietal cortex, left (thick arrow) worse than right. The left-sided posterior cingulate gyrus is also asymmetrically more hypometabolic (thin arrow). (Right) Example of more advanced AD, with decreased bifrontal metabolism (white arrows) in addition to decreased biparietal metabolism (thin arrows). Sensorimotor cortex is prominent (thick arrows).

Management ▶ There is no known cure for AD. ▶ Cholinesterase inhibitors may slow the rate of AD progression but do not prevent or reverse it. ▶ Cholinesterase inhibitors are used for both AD and DLB, but antipsychotics, which can be effective in AD, can cause dangerous side effects in patients with DLB.

Further Readings Herholz K. FDG PET and differential diagnosis of dementia. Alzheim Dis Assoc Disord. 1995;9:6–16. Waxman A, et al. Society of Nuclear Medicine Procedure Guideline for FDG PET Brain Imaging, version 1.0, 2009 (www.snm. org/guidelines).

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Case 5 History ▶ A 58-year-old man with altered mental status.

Figure 5.1 

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Case 5  Frontotemporal Dementia

Figure 5.2  Radiopharmaceutical/Dose/Procedure: 99mTc-HMPAO/925 MBq (25 mCi)/SPECT imaging 90 minutes after injection.

Findings ▶ Decreased bilateral frontal and temporal perfusion ▶ Normal parietal perfusion ▶ Normal cerebellar and basal ganglia perfusion. Differential Diagnosis ▶ Typical finding of frontotemporal dementia (FTD). Teaching Points ▶ FTD is pathologically associated with Tau inclusions. ▶ MRI may be normal or may demonstrate frontal and/or anterior temporal atrophy. ▶ FDG-PET is commonly used to distinguish AD from frontotemporal dementia (FTD), which, as the name

suggests, affects the frontal and temporal cortex. In FTD, the frontal cortex is more severely affected than the parietal cortex. ▶ Perfusion SPECT may also be used to assess dementia.

Management ▶ There is no cure for FTD. ▶ Antidepressant and antipsychotic medication may be helpful. ▶ Supportive care is needed. Further Readings Herholz K. FDG PET and differential diagnosis of dementia. Alzheim Dis Assoc Disord. 1995;9:6–16. Waxman A, et al. Society of Nuclear Medicine Procedure Guideline for FDG PET Brain Imaging, version 1.0, 2009 (www.snm. org/guidelines).

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Case 6 History ▶ A 65-year-old man with cognitive decline, tremor, and hallucinations.

Figure 6.1 

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Case 6  Dementia with Lewy Bodies (DLB)

Figure 6.2 

Figure 6.3 

Figure 6.4 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/370 MBq (10 mCi)/PET imaging 1 hour after injection (Figure 6.1) and 123I-Ioflupane (DaTscan®)/148 MBq (4 mCi)/SPECT imaging 3–6 hours after injection (Figure 6.3).

Findings ▶ Figure 6.2: Bilaterally decreased metabolism in the parietal, temporal, and occipital cortices (solid arrows), as well as the posterior cingulate gyrus (dotted arrow); normal metabolism in the frontal cortex.

▶ Figure 6.3 (DaTscan in the same patient): Preserved uptake in the bilateral caudate nuclei (white arrows) and markedly decreased uptake in the bilateral putamen (black arrows).

▶ Figure 6.4: Normal DaTscan in a different patient for comparison.

Differential Diagnosis ▶ Alzheimer disease (AD)—unlikely given occipital hypometabolism. Teaching Points ▶ DaTscan (dopamine transporter imaging): 123I-Ioflupane is a cocaine analog approved by the FDA for the

evaluation of dopamine transport. DaT is visualized in the striatum, where nigrostriatal neurons synapse with postsynaptic neurons using dopamine as a neurotransmitter. ▶ Parkinsonian symptoms include bradykinesia, resting tremor, rigidity, and postural instability. ▶ Parkinsonian syndromes with abnormal DaTscan will likely respond to dopaminergic therapy. These include Parkinson’s disease (most common), progressive supranuclear palsy, multisystem atrophy, corticobasal degeneration, and DLB. These cannot be distinguished from one another by DaTscan; FDG-PET often aids in the differential diagnosis. ▶ Non-neurodegenerative parkinsonism (i.e., essential tremor, drug-induced parkinsonism, and psychogenic parkinsonism) is characterized by normal striatal dopaminergic transport and a normal DaTscan. These will not respond to dopaminergic therapy. ▶ DaTscan is primarily used in the United States and Europe to evaluate parkinsonism. In Europe, DaTscan is also used clinically to distinguish between DLB and AD. This indication is not approved in the United States as of March 2015.

Management ▶ There is no cure for DLB. ▶ Treatments are aimed at controlling the symptoms. ▶ See Case 4. Further Readings Djang D, et al. SNM Practice Guideline for Dopamine Transporter Imaging with 123I-Ioflupane SPECT, version 1.0 J Nucl Med. 2012;53:154–163. McKeith I, et al. Diagnosis and management of dementia with Lewy bodies: third report of the DLB Consortium. Neurology. 2005;65:1863–1872. Weintraub D, Hurtig HI. Presentation and management of psychosis in parkinson’s disease and dementia with Lewy bodies. Am J Psychiatry. 2007;164:1491–1498.

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Case 7 History ▶ A 72-year-old woman with history of chronic stroke who presents for PET for initial staging for lung cancer.

Figure 7.1 

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Case 7  Crossed Cerebellar Diaschisis Due to Chronic Infarct

Figure 7.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/370 MBq (10 mCi)/PET imaging 1 hour after injection.

Findings ▶ White matter hypodensity within the posterior left frontal white matter and cortex on CT (white arrow), with associated hypometabolism on FDG-PET (thin arrow) is related to remote history of infarct. Infarct within the white matter is difficult to see on FDG PET because normal white matter metabolism is low. ▶ The contralateral cerebellar hemisphere is hypometabolic (thick arrow).

Differential Diagnosis Based on PET Findings ▶ Stroke, acute or chronic (CT or MRI will aid with diagnosis) ▶ Low-grade glioma ▶ Interictal focus of epileptogenesis ▶ Prior surgery ▶ Radiation field ▶ Remote trauma Teaching Points ▶ Crossed cerebellar diaschisis describes hypometabolism in the cerebellar hemisphere contralateral to

deactivated cortex due to disrupted corticopontocerebellar fibers. The primary injury may be in the cortex or deep nuclei. ▶ Crossed cerebellar diaschisis is a common benign physiologic phenomenon seen on PET or SPECT in the presence of supratentorial lesions, including tumor, stroke, or trauma. The cerebellar metabolic depression is typically asymptomatic, and the effect frequently resolves when occurring with stroke but may persist when associated with brain tumors. It is important not to mistake it for an additional cerebellar lesion.

Management ▶ None. The cerebellar finding in this particular case is primarily of academic interest. In the setting of acute stroke, the primary team should be notified.

Further Readings Baron JC, et al. ‘Crossed cerebellar diaschisis’ in human suptratentorial brain infarction. Trans Am Neurol Assess. 1980;105:459–461. Brunberg JA, et al. Crossed cerebellar diaschisis: occurrence and resolution demonstrated with PET during carotid temporary balloon occlusion. Am J Neuroradiol. 1992;13:58–61. Flores LG II, et al. Crossed cerebellar diaschisis: analysis of iodine-123-IMP SPECT imaging. J Nucl Med. 1995;36:399–402.

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Case 8 History ▶ A 78-year-old man with gait disturbance, urinary incontinence, and dementia.

6 Hrs

24 Hrs

48 Hrs

Figure 8.1 

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Case 8  Radionuclide Cisternogram: Normal Pressure Hydrocephalus 6 Hrs

24 Hrs

48 Hrs

Figure 8.2  Radiopharmaceutical/Dose/Procedure: 111In-DTPA/0.3–0.5 mCi/Imaging at multiple time points after intrathecal administration.

Findings ▶ 6 h: Tracer is seen in the cerebrospinal fluid (CSF) space within the basal cisterns and lateral ventricles (arrows). ▶ 24 h: Tracer migrates slowly along the bilateral sylvian fissures and interhemispheric fissure but fails to ascend to the cerebral convexities. Tracer activity persists in the lateral ventricles.

▶ 48 h: Delayed ascent of tracer toward the cerebral convexities. Persistent activity in the lateral ventricles. Differential Diagnosis ▶ None—typical appearance demonstrated. Teaching Points ▶ Normal pressure hydrocephalus (NPH) is characterized by a triad of symptoms: urinary incontinence, dementia, and ataxia (also called “wet, weird, and wobbly”).

▶ CSF pressure is normal, and there is often no significant cortical atrophy on CT. ▶ Cisternography is used to identify patients with NPH who may improve with CSF shunting from the ventricles to the peritoneal cavity, right atrium of the heart, or the pleural cavity.

▶ 111In-DTPA is the only radiotracer FDA approved for injection into the CSF space. For this study, tracer is

injected by lumbar puncture. Normally, tracer should ascend to the basal cisterns by 2–4 hours, the ventricles and suprasellar cisterns by 4–6 hours, and the cerebral convexities by 24 hours, with no significant activity in the lateral ventricles at 24 hours or later. Mild transient activity in the lateral ventricles may occasionally be seen, especially in patients with brain atrophy, but should not persist beyond 24 hours. In patients with NPH, tracer enters the lateral ventricles by 4–6 hours, earlier than normal, and persists up to several days.

Management ▶ Patients with NPH may benefit from CSF shunting. CSF shunting has been shown to reverse the symptoms characteristic of NPH in as many as 81% of patients.

▶ This CSF flow study is currently not used often to diagnose NPH. Neurosurgeons prefer a lumbar drain trial. Further Readings Black P, et al. CSF shunts for dementia, incontinence, and gait disturbance. Clin Neurosurg. 1985;32:632–651. Jacobs M, et al. Radionuclide cisternography and MRI in the evaluation of normal pressure hydrocephalus. J Nucl Med. 1989;14:819–884. Poca MA, et al. Is the placement of shunts in patients with idiopathic normal-pressure hydrocephalus worth the risk? Results of a study based on continuous monitoring of intracranial pressure. J Neurosurg. 2004 May;100:855–866.

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Case 9 History ▶ A 72-year-old woman with VP shunt placed for NPH. Now with recurrence of gait disturbance and memory loss. Assess for shunt malfunction.

Ant

Post

Ant Chest

Post Chest

Ant Abdomen

Post Abdomen

Figure 9.1  Early images

Ant Abdomen

Post Abdomen

Figure 9.2  Delayed images

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Case 9  Normal Ventriculoperitoneal (VP) Shunt Flow

Ant head

Post abdomen

Ant abdomen

Figure 9.4 

Figure 9.3 

15 min

Anterior & Posterior head

3 hours

Anterior & Posterior head

Anterior & Posterior abdomen

24 hours

Anterior & Posterior head

Anterior & Posterior abdomen/pelvis

Figure 9.5  Radiopharmaceutical/Dose/Procedure: 111In-DTPA/0.5 mCi/VP shunt imaging after injection into the shunt reservoir (distal tubing is compressed during injection so that tracer enters the ventricles first).

Findings (Figure 9.3) ▶ Tracer enters the lateral ventricles (left black arrow), indicating patent proximal tubing between the reservoir and the lateral ventricle.

▶ Normal tracer migration from the ventricles to the thecal sac (white arrrow). ▶ Prompt tracer passage through the distal tubing (thick arrow) to the peritoneal cavity in the right abdomen, indicating patent distal tubing; faint activity in the spinal thecal sac (dotted arrows), which should be distinguished from the catheter.

Differential Diagnosis ▶ None: typical appearance demonstrated. Teaching Points ▶ Obstruction is a main cause of shunt failure; may occur either in the proximal or distal tubing, often due to CSF protein buildup.

▶ Defective portion of a blocked VP shunt often needs to be surgically revised. ▶ The tubing may also break or leak. Examples of Obstructed Distal Limb ▶ Figure 9.4 (partial obstuction): On KUB, shunt tubing is coiled in the peritoneum (small white arrow). The

initial scintigraphic image (middle) shows tracer entering ventricles and migrating inferiorly along the thecal sac. Delayed image of the abdomen at 4 hours (right) shows activity in the thecal sac at the lumbar level (large white arrow) and the abdominal VP shunt tubing (small white arrow), a cutoff of activity indicating the level of obstruction (large black arrow) without discernible tracer pooling in the peritoneal space, and physiologic tracer excretion in the bladder (small black arrow). Findings are suggestive of obstruction near the distal tip of tubing. ▶ Figure 9.5 (complete obstruction): Tracers enters the ventricles and migrates within the CSF space as expected but never enters the distal limb.

Management ▶ Surgical shunt revision. Further Readings

MacDonald A, Burrell S. Infrequently performed studies in nuclear medicine: Part 2. J Nucl Med Technol. 2009;37:1–13. Samuel R, et al. Failure of cerebrospinal fluid shunts, Part I. Pediatric Neurol. 2006;34:83–92. Samuel R, et al. Failure of cerebrospinal fluid shunts, Part II. Pediatric Neurol. 2006;34:171–176.

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Case 10 History ▶ History of lung cancer and brain metastases treated with radiosurgery. Follow-up MRI 6 months

later shows an enlarging, enhancing left occipitoparietal mass in the region of prior radiosurgery.

Figure 10.1 

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Case 10  Recurrent Malignancy

Figure 10.2 

Figure 10.3  18F-FDG/10

Radiopharmaceutical/Dose/Procedure: mCi/PET 1 hour after injection (Figure 10.2; left, color image) and 201Tl-chloride/111 MBq (3 mCi)/Early SPECT 2–5 minutes after injection (right, color image), delayed SPECT optional. Note: PET and SPECT studies were performed on separate days.

Findings ▶ Figure 10.2 shows intense thallium uptake in the left parieto-occipital region (dotted arrow), corresponding

to the site of contrast enhancement on MRI. In that region, focal FDG uptake is greater than that of the surrounding irradiated cortex (solid arrow), although not as intense as normal gray matter. These findings are suspicious for tumor recurrence. ▶ Figure 10.3: Postoperative MRI. Pathology revealed poorly differentiated adenocarcinoma with extensive necrosis.

Differential Diagnosis ▶ Post-radiation necrosis with metabolically active granulation tissue (intense inflammatory response). Teaching Points ▶ Post-treatment necrosis is often clinically and radiographically (MRI) indistinguishable from tumor recurrence. Both enhance with contrast.

▶ In general, the higher the FDG uptake, the more likely the diagnosis of tumor. However, significant overlap

in FDG uptake exists between tumor and tissue necrosis, making differential diagnosis challenging. Because this is particularly more difficult in the early post-radiation period, the recommendation is not to perform the study within at least 1–3 months after radiation. ▶ Intense FDG uptake in the normal gray matter may interfere with the interpretation. Correlation with MRI is helpful. It is preferable to fuse the PET to the most recent MRI (T1 post-contrast or 3D acquisition with contrast) for the interpretation. This is often more helpful than a side-by-side visual comparison because the axial planes of brain PET and MRI are often different from one another. Many fusion software packages are available. ▶ Thallium-201 is taken up by viable cells, via a Na-K ATPase, where the blood-brain barrier is broken. There is no confounding physiologic uptake in the surrounding cortex. However, inflammatory cells are also viable and can take up thallium or FDG. Further Readings Chen W. Clinical applications of PET in brain tumors. J Nucl Med. 2007;48:1468–1481. Horky LL, et al. PET and SPECT in brain tumors and epilepsy. Neurosurg Clin N Am. 2011;22:169–184. Kline JL, et al. Single-photon emission CT in the evaluation of recurrent brain tumor in patients treated with gamma knife radiosurgery or conventional radiation therapy. AJNR. 1996;17:1681–1686.

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Part 2

Nuclear Inflammation/ Infection Imaging Christopher J. Palestro

Case 11 History ▶ None.

Patient A

Figure 11.1

25

Case 11  Interstitial Nephritis

Patient A

Patient B

Figure 11.2 Radiopharmaceutical/Dose/Procedure: 67Ga-citrate/10 mCi/Imaging at 48 hours after injection.

Findings (Patient A) ▶ Intense diffuse, bilateral renal uptake (arrows), more intense than spinal uptake. Differential Diagnosis ▶ Pyelonephritis ▶ Lymphoma Teaching Points (Interstitial Nephritis) ▶ Most common causes are medications, especially antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs).

▶ Presentation: acute renal failure, nonspecific signs and symptoms, azotemia, peripheral eosinophilia, microscopic hematuria, proteinuria, esoinophils in the urine, predominantly tubular involvement.

▶ Gallium imaging: ■ Is useful in patients with acute renal failure to differentiate acute interstitial nephritis, characterized by

intense renal activity (Patient A), from acute tubular necrosis, characterized by little or no renal uptake of gallium (Patient B); ■ Should be performed at least 48 hours after injection because the kidneys are the principal route of excretion of gallium during the first 24 hours after injection.

Management ▶ Early treatment with corticosteroids improves prognosis. Further Readings Joaquim AI, et al. Ga-67 scintigraphy in the differential diagnosis between acute interstitial nephritis and acute tubular necrosis: an experimental study. Nephrol Dial Transplant. 2010;25:3277–3282. Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia: Lippincott, Williams and Wilkins; 2012:1339–1352.

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Case 12 History ▶ A 45-year-old man treated for urinary tract infection with fever and low back pain. A posterior planar image (A) and a selected coronal SPECT image (B) are shown in Figure 12.1.

A

B

Figure 12.1 

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Case 12 Spinal Osteomyelitis with Adjacent Psoas Abscess A

B

C

D

Figure 12.2  Radiopharmaceutical/Dose/Procedure: 67Ga-citrate/10 mCi/Imaging at 48 hours after injection.

Findings ▶ Gallium imaging: Posterior planar (panel A) and coronal SPECT (panel B) images show intense uptake in the lower lumbar spine with extension of the abnormal activity into the adjacent soft tissues.

▶ Bone scan performed 2 days earlier: ■ The posterior planar image (panel C) shows nonspecific mild uptake at the L4/L5 level. ■ The coronal SPECT image (panel D) demonstrates increased activity in two contiguous vertebrae (arrows), but the psoas abscess is not seen.

Differential Diagnosis ▶ Tumor ▶ Compression fracture based on bone scan alone but unlikely when combined with gallium imaging ▶ Degenerative changes based on bone scan alone but unlikely when combined with gallium imaging. Teaching Points ▶ Spinal osteomyelitis: ■ Predilection for the elderly; 2%–7% of all cases of osteomyelitis; results from bacteremia or direct bacterial

inoculation; most common causative agent is Staphylococcus aureus; usually confined to the vertebral body and intervertebral disc; posterior element involvement is present in up to 20% of cases; may be accompanied by soft tissue abscess. ▶ Presentation: ■ 50% of patients are symptomatic for 3 or more months; 90% of patients present with back or neck pain; 20% of patients present with a neurological defect; laboratory tests are of limited value; less than 50% of patients present with an elevated leukocyte count; erythrocyte sedimentation rate (ESR) is elevated in more than 90% of the cases; gram stain and culture is most useful laboratory test. ▶ Gallium imaging: ■ Improves the specificity of the bone scan ■ May detect infection earlier than the bone scan ■ Identifies accompanying soft tissue infection ■ Adjunct to, not replacement for, MRI ■ Accuracy highest when SPECT or SPECT/CT is performed.

Management ▶ Antibiotics and surgery when indicated. Further Readings Gemmel F, et al. Radionuclide imaging of spinal infections. Eur J Nucl Med Mol Imag. 2006;33:1226–1237. Love C, et al. Diagnosing spinal osteomyelitis: a comparison of bone and Ga-67 scintigraphy and magnetic resonance imaging. Clin Nucl Med. 2000;25:963–977. Palestro CJ, et al. Radionuclide imaging of musculoskeletal infection: conventional agents. Semin Musculoskelet Radiol. 2007;11:335–352.

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Case 13 History ▶ A 58-year-old woman with lymphadenopathy and dyspnea.

Figure 13.1 

Figure 13.2 

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Case 13 Sarcoidosis

Figure 13.3 

Figure 13.4 

Radiopharmaceutical/Dose/Procedure: 67Ga-citrate/8 mCi/Planar and SPECT-CT imaging 48 hours after injection.

Findings ▶ Whole body planar images (Figure 13.3): ■ Patchy diffuse bilateral pulmonary uptake ■ Focally increased radiotracer uptake in right paratracheal and bilateral hilar lymph nodes (less clearly seen due to superimposed pulmonary uptake)

■ Focal uptake in the celiac/periportal region (partially obscured by the liver) ■ Bilateral inguinal lymph nodes (arrows).

▶ Selected coronal and transaxial SPECT/CT images (Figure 13.4): ■ Increased uptake in mediastinal and bilateral hilar lymph nodes resembles the Greek letter lambda (the “lambda sign”), which is strongly suggestive of sarcoid.

■ Increased uptake in celiac/periportal lymph nodes is more clearly identified. Differential Diagnosis ▶ Lymphoma ▶ Lymphangitic spread of any malignancy ▶ Opportunistic infection ▶ Interstitial lung disease ▶ Pneumoconioses. Teaching Points ▶ Etiology: Unknown; multisystem granulomatous disease usually affecting young and middle-aged adults ▶ Presentation: Varies with organs involved; pulmonary involvement characterized by dry cough, dyspnea, chest pain, hemoptysis (rarely)

▶ Gallium imaging: ■ Useful for evaluating extent of disease, monitoring response to therapy, detecting recurrent disease, and differentiating scarring from active disease

■ Intensity of pulmonary activity correlates with disease activity ■ Not specific and cannot be used to make the diagnosis of sarcoid. Management ▶ Varies with organs involved; corticosteroids are mainstay of treatment. ▶ Other agents including methotrexate, azathioprine, and infliximab, used in steroid-resistant disease, and in patients who cannot tolerate steroids.

Further Readings Dempsey OJ, et al. Sarcoidosis. BMJ. 2009;339:b3206. Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia: Lippincott, Williams and Wilkins; 2012:1339–1352. Sulavik SB, et al. Specificity and sensitivity of distinctive chest radiographic and/or 67Ga images in the noninvasive diagnosis of sarcoidosis. Chest. 1993;103:403–409.

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Case 14 History ▶ A 35-year-old man, intravenous drug abuser, with 3 weeks of progressive shortness of breath, fever, and dry cough.

Figure 14.1 

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Case 14  Pneumocystis Carinii (Jiroveci) Pneumonia (PCP)

Figure 14.2  Radiopharmaceutical/Dose/Procedure: 67Ga-citrate/10 mCi/Imaging 48 hours after injection.

Findings ▶ Diffuse intense uptake in both lungs ■ Intensity of left lung uptake equal to that of the liver ■ Intensity of right lung uptake exceeds that of the liver. Differential Diagnosis ▶ Other opportunistic infections ▶ Pulmonary drug toxicity ▶ Sarcoid ▶ Fibrosing alveolitis (idiopathic pulmonary fibrosis). Teaching Points ▶ Etiology: Alveolar macrophages without CD4+ cells are unable to eradicate Pneumocystis organisms, resulting in uncontrolled organism replication and infection.

▶ Presentation: ■ Progressive exertional dyspnea ■ Nonproductive cough ■ Fever, chills ■ Tachypnea ■ Tachycardia. ▶ Gallium imaging: ■ Very sensitive for detecting PCP ■ Typically presents as diffuse, bilateral intense pulmonary uptake that is at least as intense as hepatic uptake ■ Negative study excludes PCP with high degree of certainty ■ More sensitive than labeled leukocyte imaging for PCP and most opportunistic infections. Management ▶ Antibiotics including trimethoprim-sulfamethoxazole and pentamidine. Further Readings Palestro CJ. The current role of gallium imaging in infection. Sem Nucl Med. 1994;24:128–141. Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia: Lippincott, Williams and Wilkins; 2012:1339–1352. Palestro CJ, et al. The use of gallium and labeled leukocyte scintigraphy in the AIDS patient. Q J Nucl Med. 1995;39:221–230.

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Case 15 History ▶ A 65-year-old patient taking 2 g/day of amoxicillin for a dental abscess.

Figure 15.1 

33

Case 15  Pseudomembranous Colitis

Figure 15.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.5 mCi/Imaging 24 hours after injection.

Findings ▶ Intense labeled leukocyte activity in transverse colon. Differential Diagnosis ▶ Inflammatory bowel disease ▶ Ischemic bowel ▶ GI bleeding ▶ Swallowed leukocytes. Teaching Points ▶ Etiology: ■ Overgrowth of normal intestinal bacterium Clostridium difficile in patients taking antibiotics ■ The colonic lining becomes inflamed and bleeds, taking on characteristic pseudomembrane appearance. ▶ Presentation: ■ Abdominal cramping ■ Bloody diarrhea ■ Fever ▶ 111In-labeled leukocyte imaging: ■ Bowel activity always is abnormal. ■ Extent of disease/involvement cannot be determined on a single image acquired several hours after injection. ■ Accurate delineation of involved areas necessitates acquisition of multiple images shortly after injection. ▶ 99mTc-labeled leukocyte imaging: ■ Bowel activity can be normal on images acquired more than 4 hours after injection. Management ▶ Discontinue offending antibiotic, treat with metronidazole. Further Readings Palestro CJ, et al. Labeled leukocyte imaging: current status and future directions. Q J Nucl Med Mol Imaging. 2009;53:105–123. Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia: Lippincott, Williams and Wilkins; 2012:1339–1352.

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Case 16 History ▶ A 44-year-old intravenous drug abuser presents with fever and bacteremia.

Figure 16.1 

35

Case 16  Spinal Osteomyelitis

Figure 16.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.54 mCi/Imaging 24 hours after injection.

Findings ▶ Labeled leukocyte study (left panel): ■ Decreased activity in the mid-thoracic spine (black arrow) ■ Apparently increased activity in the lower thoracic/upper lumbar region (white arrow) due to superimposed left hepatic lobe activity

▶ MRI (right panel) performed 1 day after the labeled leukocyte study demonstrated diminished intervertebral

disc space with hypointense T1 and hyperintense T2 signal abnormalities and enhancement of the disc space and vertebral bodies consistent with osteomyelitis/discitis.

Differential Diagnosis ▶ Treated osteomyelitis ▶ Tumor ▶ Compression fracture ▶ Paget disease ▶ Previous radiation ▶ Any condition that causes marrow replacement. Teaching Points ▶ Etiology: See Case 12 ▶ Presentation: See Case 12 ▶ Labeled leukocyte imaging: ■ Should not be used for suspected spinal osteomyelitis because more than half of all cases in adults present as nonspecific photopenia.

■ Explanation for the photopenia is unknown. The photopenic presentation also occurs with 99mTc-labeled leukocytes.

■ Osteomyelitis should be considered whenever spinal photopenia is present on a labeled leukocyte image. Management ▶ Antibiotics and surgery as indicated. Further Readings Palestro CJ, et al. Radionuclide diagnosis of vertebral osteomyelitis: indium-111-leukocyte and technetium-99m-methylene diphosphonate bone scintigraphy. J Nucl Med. 1991;32:1861–1865. Palestro CJ, et al. Radionuclide imaging of musculoskeletal infection: conventional agents. Semin Musculoskelet Radiol. 2007;11:335–352.

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Case 17 History ▶ An 81-year-old woman s/p femoral-popliteal prosthetic vascular graft months prior presents with

wound infection, fever, and blood cultures positive for methicillin-resistant Staphyllococcus aureus (MRSA).

Figure 17.1 

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Case 17  Femoral-Popliteal Prosthetic Vascular Graft Infection

Figure 17.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.5 mCi/Scan 24 hours after injection.

Findings ▶ A tubular shaped area of abnormal labeled leukocyte accumulation (arrows) along the medial aspect of the right lower extremity extending from the proximal thigh to the knee.

▶ Focal labeled leukocyte accumulation at the medial aspect of the right knee (arrowhead) corresponds to perigraft abscess found at surgery.

Differential Diagnosis ▶ Thrombosed uninfected graft ▶ Recently placed (within 1 month or less) graft ▶ Perigraft hematoma. Teaching Points ▶ Etiology: Two principal mechanisms ■ Bacterial contamination at time of implantation ■ Hematogenous or lymphogenous transfer of organisms from remote site. ▶ Presentation: Varies with interval after implantation: ■ Early (up to 4 months) infections characterized by fever, leukocytosis, bacteremia, and graft dysfunction; ■ Late infections are more subtle; fever usually is absent. ▶ Labeled leukocyte imaging: ■ Very sensitive (> 90%) for detecting prosthetic graft infection ◆ Sensitivity is not affected by duration of symptoms or previous antibiotic therapy. ◆ Specificity is more variable. ■ Also sensitive for detecting mycotic aneurysms ■ Sensitive and specific for detecting hemodialysis access site infection ■ Not useful for detecting bacterial endocarditis. Management ▶ Removal of the infected graft, when possible, is treatment of choice, along with adjunctive antimicrobial therapy. Further Readings Palestro CJ, et al. Indium-111-labeled leukocyte scintigraphy in hemodialysis access-site infection. J Nucl Med. 1990;31:319–324. Palestro CJ, et al. Labeled leukocyte imaging: current status and future directions. Q J Nucl Med Mol Imaging. 2009;53:105–123.

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Case 18 History ▶ An anterior image taken at 2 hours after administration of 111In-labeled leukocytes in a patient with fever.

Figure 18.1 

39

Case 18 Normal Physiological Pulmonary Uptake of Labeled Leukocytes on Early Images 2 hr

24 hr

Figure 18.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.5 mCi/Imaging at 2 hours and 24 hours after injection.

Findings ▶ Diffuse homogeneous bilateral pulmonary activity at 2 hours after injection ▶ Pulmonary activity has completely cleared at 24 hours ▶ Labeled leukocyte accumulation in the bone marrow and spleen is higher at 24 hours. Differential Diagnosis ▶ Adult respiratory distress syndrome ▶ Sepsis ▶ Opportunistic infection ▶ Pulmonary drug toxicity ▶ Radiation pneumonitis ▶ Hemodialysis. Teaching Points ▶ Etiology: Probably due to leukocyte activation during the in-vitro labeling process, which impedes movement through the pulmonary vascular bed, prolonging passage through the lungs.

▶ Presentation: Physiologic pulmonary uptake of labeled leukocytes is characterized by intense, diffuse bilateral lung activity on images obtained shortly after injection, which clears rapidly, usually reaching background levels by 4 hours. ▶ Diffuse pulmonary activity on labeled leukocyte images rarely is associated with bacterial pneumonia. ▶ Lungs should be evaluated only on images obtained more than 4 hours after injection.

Management ▶ None. Further Readings Love C, et al. Pulmonary activity on labeled leukocyte images: physiologic, pathologic, and imaging correlations. RadioGraphics. 2002;22:1385–1393.

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Case 19 History ▶ A 17-year-old man with sickle cell disease, fever, and left shoulder pain.

Figure 19.1 

41

Case 19  Localized Bone Marrow Expansion WBC

SC

Figure 19.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.5 mCi/leukocyte scan 24 hours after injection (left) immediately followed by 99mTc-sulfur colloid/370 MBq (10 mCi)/bone marrow imaging 1 hour after injection (right).

Findings ▶ Focally increased activity in the left humeral head both on the labeled leukocyte image (WBC) and on the sulfur colloid bone marrow image (SC).

Differential Diagnosis ▶ Osteomyelitis based on leukocyte imaging alone, but unlikley given increased sulfur colloid uptake. Teaching Points ▶ Leukocytes accumulate both in infection and in bone marrow. ■ Therefore, it is not always possible to differentiate between infection and bone marrow on labeled leukocyte studies alone.

■ Neither the distribution (e.g., asymmetry) nor intensity of uptake on labeled leukocyte studies alone is a reliable criterion for differentiating between infection and marrow.

▶ Diagnosing osteomyelitis on labeled leukocyte imaging is best done by performing complementary bone

marrow imaging with 99mTc-sulfur colloid. ■ Both leukocytes and sulfur colloid accumulate in bone marrow. ◆ When the distribution of activity on the labeled leukocyte and bone marrow images is the same (spatially congruent), the activity on the labeled leukocyte study is due to marrow and the test is negative for osteomyelitis. ■ Leukocytes accumulate in infection, sulfur colloid does not. ◆ When there is activity on the labeled leukocyte image without corresponding activity on the bone marrow image (spatially incongruent), the activity on the labeled leukocyte study is due to infection and the test is positive for osteomyelitis.

Management ▶ Supportive. Further Readings Palestro CJ, et al. Combined labeled leukocyte and technetium 99m sulfur colloid bone marrow imaging for diagnosing musculoskeletal infection. RadioGraphics. 2006;26:859–870.

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Case 20 History ▶ A 55-year-old diabetic patient with painless, swollen right foot.

Figure 20.1 

Figure 20.2 

43

Case 20  Osteomyelitis Involving a Neuropathic Joint

WBC

Figure 20.3 

SC

Figure 20.4  111In-labeled

Radiopharmaceutical/Dose/Procedure: leukocytes/0.5 mCi/leukocyte scan 24 hours after injection (left) immediately followed by 99mTc-sulfur colloid/370 MBq (10 mCi)/bone marrow imaging 1 hour after injection (right).

Findings ▶ Plain radiographs of the right foot (lateral and oblique) (Figure 20.3): ■ Extensive joint derangement with rocker bottom deformity, osseous erosions, bony fragmentation, and debris formation compatible with neuropathic arthropathy.

■ Superimposed osteomyelitis cannot be excluded. ■ Patient is s/p 5th ray resection.

▶ Labeled leukocyte image (WBC) and corresponding sulfur colloid image (SC)—lateral projection (Figure 20.4): ■ Focally increased leukocyte activity in the right mid-foot (thin arrow) and no increased bone marrow activity in the corresponding area (thick arrow). In other words, the distribution of activity is spatially incongruent, consistent with osteomyelitis. ■ Spatially congruent, focally increased uptake in the left calcaneus on both the labeled leukocyte and sulfur colloid images. Therefore, the labeled leukocyte activity in this bone is due to marrow, not infection.

Differential Diagnosis ▶ Uninfected neuropathic joint based on labeled leukocyte imaging, but unlikely given the absence of corresponding increased sulfur colloid uptake.

▶ Soft tissue infection, less likely. Specificity may be further improved by SPECT or SPECT/CT imaging. Teaching Points ▶ Etiology: Most commonly due to contiguous spread from adjacent infected ulcer. ▶ Presentation: Painless swelling and adjacent soft tissue ulcer. ▶ Labeled leukocytes accumulate in the uninfected neuropathic joint, primarily due to the presence of

hematopoietically active marrow. ■ Labeled leukocyte activity in the neuropathic joint does not necessarily indicate infection. ■ The best radionuclide method for determining the presence of infection of a neuropathic joint is to perform combined labeled leukocyte/bone marrow imaging. ▶ See Teaching Points in Case 19.

Management ▶ Antibiotics; amputation when indicated. Further Readings Palestro CJ et al. Marrow versus infection in the Charcot joint: Indium-111 leukocyte and technetium-99m sulfur colloid scintigraphy. J Nucl Med. 1998;39:346–350. Palestro CJ, et al. Combined labeled leukocyte and technetium 99m sulfur colloid bone marrow imaging for diagnosing musculoskeletal infection. RadioGraphics. 2006.;26:859–870.

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Case 21 History ▶ A 56-year-old patient underwent bilateral total knee replacement surgery 2 months previously. Presents with painful right knee replacement, elevated ESR, and normal C-reactive protein.

Figure 21.1 

45

Case 21 Infected Right Total Knee Replacement and Hypercellular Bone Marrow Around the Left Total Knee Replacement

WBC

SC

Figure 21.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.5 mCi/leukocyte scan 24 hours after injection (left) immediately followed by 99mTc-sulfur colloid/370 MBq (10 mCi)/bone marrow imaging 1 hour after injection (right).

Findings ▶ Spatially incongruent distribution of activity in the right knee joint space on the labeled leukocyte image

(WBC) and the sulfur colloid bone marrow image (SC). ■ The combined study is positive for infection. ▶ Note that the periprosthetic leukocyte activity around the asymptomatic left knee replacement is even more intense than on the right but spatially congruent on the marrow images, consistent with active bone marrow.

Differential Diagnosis ▶ Superficial soft tissue infection adjacent to the right knee replacement. Teaching Points ▶ Etiology: ■ Varies with time since implantation ■ Up to 1 year likely due to infection at time of surgery ■ After 1 year usually due to hematogenous spread of infection. ▶ Presentation: ■ Pain, swelling, erythema around the prosthetic joint ■ ESR and/or C-reactive protein usually, but not always abnormal ■ Circulating leukocyte count usually normal. ▶ Labeled leukocyte activity around the prosthetic joint does not necessarily indicate infection. It may just

reflect periprosthetic bone marrow uptake of labeled leukocytes. The best imaging method for determining whether or not a prosthetic joint is infected is combined labeled leukocyte/bone marrow imaging. ■ See Teaching Points in Case 19.

Management ▶ Excisional arthroplasty followed by several weeks of antibiotic therapy, and eventually revision arthroplasty. Further Readings Love C, et al. Nuclear medicine and the infected joint replacement. Sem Nucl Med. 2009;39:66–78. Palestro CJ, et al. Combined labeled leukocyte and technetium 99m sulfur colloid bone marrow imaging for diagnosing musculoskeletal infection. RadioGraphics. 2006;26:859–870 Palestro CJ, et al. Radionuclide imaging of musculoskeletal infection: conventional agents. Semin Musculoskelet Radiol. 2007;11:335–352.

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Case 22 History ▶ A 75-year-old patient with a retroperitoneal collection on CT adjacent to an abdominal aortic aneurysm.

Figure 22.1 

Figure 22.2 

47

Case 22  Abdominal Abscess

Figure 22.3  Radiopharmaceutical/Dose/Procedure:

Figure 22.4  111In-labeled

leukocytes/0.5 mCi/Scan 24 hours after injection.

Findings ▶ CT (Figure 22.4, left): ■ A 5.6 × 4.6 cm abdominal aortic aneurysm with an adjacent thick-walled retroperitoneal collection (white arrow) measuring 4.1 × 5.1 × 6.7 cm and suspicious for abscess

■ Bilateral renal cysts.

▶ Labeled leukocyte images, planar (Figure 22.3) and coronal SPECT (Figure 22.4, right): ■ A discrete area of increased activity (arrow) in the mid-abdomen, anterior to the vertebral column, corresponding to the retroperitoneal collection.

Differential Diagnosis ▶ Mycotic aneurysm ▶ Infected hematoma. Teaching Points ▶ Etiology: Variable. ▶ Presentation: Varies with location; fever, local pain, elevated leukocyte count. ▶ Labeled leukocyte imaging is an adjunct to anatomic imaging modalities and facilitates the differentiation of abscess from other fluid collections as well as from tumor, and even normal postoperative changes.

Management ▶ CT-guided drainage. Further Readings Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia: Lippincott, Williams and Wilkins; 2012:1339–1352. Palestro CJ, et al. Labeled leukocyte imaging: current status and future directions. Q J Nucl Med Mol Imaging. 2009;53:105–123.

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Case 23 History ▶ An 85-year-old patient with dementia, fever, and elevated leukocyte count.

Figure 23.1 

49

Case 23  Physiologic Uptake Around Entry Site of a Feeding Gastrostomy

Anterior

Left lateral

Figure 23.2  Radiopharmaceutical/Dose/Procedure: 111In-labeled leukocytes/0.6 mCi/Scan 24 hours after injection.

Findings ▶ Focally increased activity (arrows) in the anterior soft tissues of the left mid-abdomen. Differential Diagnosis ▶ Soft tissue infection ▶ Suture abscess ▶ Bleeding/hematoma. Teaching Points ▶ Etiology: Ostomies are granulating wounds; leukocytes (granulocytes) accumulate at granulating wounds as part of the healing process.

▶ Presentation: Asymptomatic. ▶ Although labeled leukocytes do not accumulate in normally healing surgical wounds, there are some

exceptions. ■ Granulating wounds such as ostomies (tracheostomies, ileostomies, colostomies, vesicostomies, etc.), open surgical wounds, skin grafts, etc., even in the absence of infection, are characterized by increased activity, which can be intense on labeled leukocyte images. ■ Focal uptake, especially when superficial in origin, requires careful clinical correlation. Without appropriate clinical history, ostomies, vascular access lines, dialysis catheters, etc., can yield false positive results. Direct visualization to confirm or exclude the presence of ostomy is also advised.

Management ▶ None. Further Readings Palestro CJ. Scintigraphic imaging of inflammation and inflammation. In: Brant WE, Helms CA, eds. Fundamentals of Diagnostic Radiology. 4th ed. Philadelphia, Lippincott, Williams and Wilkins; 2012:1339–1352. Palestro CJ, et al. Role of radionuclide imaging in the diagnosis of postoperative infection. RadioGraphics. 2000;20:1649–1660. Palestro CJ, et al. Labeled leukocyte imaging: current status and future directions. Q J Nucl Med Mol Imaging. 2009;53:105–123.

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Case 24 History ▶ A 55-year-old woman with stage I breast carcinoma; staging.

Figure 24.1 

51

Case 24 Sarcoidosis

Figure 24.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/14 mCi/PET-CT 1 hour after injection.

Findings ▶ Numerous FDG-avid foci (SUVmax 13) in the mediastinum and bilateral hilar region corresponding to enlarged lymph nodes on the CT component of the examination.

Differential Diagnosis ▶ Lymphoma ▶ Metastatic disease. Teaching Points ▶ Etiology: See Case 13. ▶ Presentation: See Case 13. ▶ FDG-PET/CT ■ FDG uptake is nonspecific and can mimic other diseases. ■ FDG-PET/CT is useful for monitoring effectiveness of therapy and also is useful in cardiac sarcoidosis. Management ▶ See Case 13. Further Readings Prabhakar HB et al. Imaging features of sarcoidosis on MDCT, FDG PET, and PET/CT. AJR. 2008;190(suppl) S1–S6. Youssef G, et al. The use of 18F-FDG PET in the diagnosis of cardiac sarcoidosis: a systematic review and metaanalysis including the Ontario experience. J Nucl Med. 2012;53:241–248.

52

Case 25 History ▶ A 75-year-old woman with 2-year-old abdominal aortic endograft, presented with fever, abdominal pain, and leukocytosis.

Image courtesy of F. Gemmel, MD

Figure 25.1 

53

Case 25  Infected Abdominal Aortic Endograft

Figure 25.2  Radiopharmaceutical/Dose/Procedure:

Figure 25.3  18F-FDG/11

mCi/PET-CT 1 hour after injection.

Findings ▶ Figure 25.2: Intense FDG uptake around the prosthesis can be appreciated in the sagittal (top), transaxial (center), and coronal (bottom) images.

▶ Figure 25.3: Diffuse FDG uptake (SUVmax 6.9) in the right and left limbs of a 3-year-old asymptomatic subclavian vascular graft.

Differential Diagnosis ▶ Aseptic inflammation. Teaching Points ▶ Etiology: See Case 17. ▶ Presentation: See Case 17. ▶ FDG-PET/CT: ■ Very sensitive for detecting prosthetic vascular graft infection. ■ Specificity is controversial. In one series, there was increased periprosthetic FDG uptake around 14/15 uninfected grafts.

■ Specificity may be improved by analyzing FDG uptake patterns in conjunction with graft appearance on the CT component of the test. Focal FDG uptake combined with irregular graft borders on CT may be more specific for infection.

Management ▶ Removal of the infected graft, when possible, is treatment of choice, along with adjunctive antimicrobial therapy

Further Readings Bleeker-Rovers CP, et al. Imaging of infectious diseases using [18F] fluorodeoxyglucose PET. Q J Nucl Med Mol Imaging. 2008;52:17–29. Spacek M, et al. Diagnostics of “non-acute” vascular prosthesis infection using 18F-FDG PET/CT: our experience with 96 prostheses. Eur J Nucl Med Mol Imaging. 2009;36:850–858. Wasselius J, et al. High 18F-FDG Uptake in synthetic aortic vascular grafts on PET/CT in symptomatic and asymptomatic patients. J Nucl Med. 2008;49:1601–1605.

54

Case 26 History ▶ A 60-year-old man with history of motor vehicle accident s/p placement of spinal hardware with draining wound.

Figure 26.1 

55

Case 26  Spinal Osteomyelitis/Infected Hardware

Figure 26.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/15 mCi/PET-CT 1 hour after injection.

Findings ▶ Heterogeneously increased FDG uptake in the left paraspinal region extending from approximately T11 to L3 (SUVmax 9.3) that tracks to an open wound in the left flank (double arrow)

▶ Focally increased FDG uptake (single arrow) in L2 (SUVmax 8.7) Differential Diagnosis ▶ Compression fracture ▶ Tumor.

Teaching Points ▶ Etiology: See Case 12. ▶ Presentation: See Case 12. ▶ FDG-PET/CT: ■ Very sensitive and moderately specific for diagnosing spinal osteomyelitis ■ May be especially useful as an adjunct to MRI for differentiating between infection and severe endplate degenerative changes

■ False positive results have been associated with uninfected spinal hardware. Management ▶ Removal of hardware, antibiotic therapy. Further Readings Gemmel F, et al. Expanding role of 18F-fluoro-D-deoxyglucose PET and PET/CT in spinal infections. Eur Spine J. 2010;19:540–551. Strobel K, et al. PET/CT in musculoskeletal infection. Semin Musculoskelet Radiol. 2007;11:353–364.

56

Case 27 History ▶ A 10-year-old girl with general malaise and intermittent fevers over several months, with

no localizing signs or symptoms. Laboratory tests, plain radiograph, and ultrasound were non-contributory.

Figure 27.1 

57

Case 27  Fever of Unknown Origin (FUO)/Non-Hodgkin Lymphoma

Figure 27.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10 mCi/PET-CT 1 hour after injection.

Findings ▶ Anterior MIP image (left): ■ Intense FDG uptake in the upper thoracic spine ■ Several foci of increased FDG uptake in the mediastinum, lungs, and liver ■ Right-sided hydroureteronephrosis. ▶ Axial image through the upper thoracic spine (right): ■ Increased FDG uptake in T3 (SUVmax 11.4) ■ Subsequent biopsy confirmed non-Hodgkin lymphoma. Differential Diagnosis ▶ Other malignancies ▶ Mycobacterial infection ▶ Sarcoid. Teaching Points ▶ Causes of FUO: ■ Infection about 20%–30% ■ Neoplasm about 10% ■ Other etiologies include vasculitis, thromboembolic disease, collagen vascular disease, granulomatous disease, cerebrovascular accidents, and drug fever.

▶ Presentation: ■ Usually defined as an illness of at least 3 weeks duration ■ With several episodes of fever exceeding 38.3ºC ■ No diagnosis after an appropriate inpatient or outpatient evaluation. ▶ FDG-PET: ■ Though not specific, the test is exquisitely sensitive, making it extremely useful in an entity with so many diverse etiologies.

■ High negative-predictive value makes it unlikely that a focal cause of the fever will be identified if the study is negative.

Management ▶ Varies with cause of the FUO. Further Reading Bleeker-Rovers CP, et al. Fever of unknown origin. Semin Nucl Med. 2009;39:81–87.

58

Case 28 History ▶ A 62-year-old patient (Patient A) with painful 5-year-old hybrid (cemented femoral component, press fit acetabular component) total hip replacement.

Patient A

Patient A

Figure 28.1 

59

Case 28  Infected Right Total Hip Replacement Patient A

Patient A

Patient B

Figure 28.2 

Patient C

Figure 28.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/25 mCi/Bone scan 2 hours after injection.

Findings (Figure 28.2) ▶ X-ray: (1) intact, aligned components; (2) lucent zone around cement-bone interface of the femoral

component may indicate loosening and/or infection; (3) thick periosteal bone formation along the medial femoral shaft, possibly related to callus from prior fracture or extensive stress reaction. ▶ Bone scan: (1) markedly increased tracer activity around femoral component of right hip prosthesis; (2) increased soft tissue activity lateral to the prosthesis; (3) increased activity distal to the prosthesis corresponding to periosteal bone formation on X-ray.

Differential Diagnosis ▶ Aseptic loosening. Teaching Points: ▶ Etiology and Presentation: See Case 21. ▶ Bone scan of hip prostheses: ■ While focal uptake at the distal tip of the femoral component suggests aseptic loosening (e.g., Patient B

[Figure 28.3] had an aseptically loosened 3-year-old right hip replacement), diffuse periprosthetic uptake generally suggests infection (Patient A). However, during the first year after implantation, periprosthetic uptake patterns are so variable that only a normal scan is helpful. Further, up to 10% of asymptomatic cemented prostheses demonstrate periprosthetic uptake beyond 1 year (Patient C). Therefore, these criteria are only modestly reliable. ■ Persistent uptake beyond 1 year is even more prevalent in porous-coated hip replacements. Data about the evolution of normal periprosthetic uptake patterns around other types of prostheses are lacking. ▶ Bone scan assessment of knee replacements also is problematic; more than 60% of femoral components and nearly 90% of tibial components more than 1 year old demonstrate persistent periprosthetic activity. ▶ Summary: ■ Bone scan is sensitive for identifying the failed joint replacement but cannot reliably determine the cause. ■ Performing 3-phase bone scan does not improve overall accuracy of BS in painful prosthetic joint evaluation (50%–70%). Bone scan is most useful as a screening test for the painful joint replacement.

Management ▶ Excisional arthroplasty, several weeks of antibiotic therapy, and eventually revision arthroplasty. Further Readings Love C, et al. Nuclear medicine and the infected joint replacement. Semin Nucl Med. 2009;39:66–78. Palestro CJ, et al. Radionuclide imaging of musculoskeletal infection: conventional agents. Semin Musculoskelet Radiol. 2007;11:335–352.

60

Part 3

Ventilation/Perfusion Lung Scintigraphy Won Jun Park, Daniel F. Worsley, Chun K. Kim

Case 29 History ▶ Shortness of breath and positive D-dimer.

Figure 29.1 

Figure 29.2 

63

Case 29  Normal Ventilation (133Xe) and Perfusion V

Q

SB

Eq 1

Eq 2

WO 1

2

3

4

5

6

7

Post

LAO

RAO

RPO

LPO

Ant

Figure 29.3 

Radiopharmaceutical/Dose/Procedure: ▶ 133Xe ventilation imaging: 10–20 mCi, performed in posterior projection if a single-head gamma camera is

used, or in RPO and LPO projections using a dual-head camera (see Case 40). ■ Single breath (SB) phase: Patient takes a deep breath in. As patient is inhaling, 133Xe gas is administered. SB image is obtained while patient holds the breath and is stopped after 30 sec (or earlier if patient can no longer hold the breath). ■ Equilibrium (EQ) phase: Patient equilibrates using the rebreathing apparatus for 3 min. Several dynamic images may be taken during rebreathing, or one equilibrium image may be taken while patient holds the breath at the end of sufficient rebreathing. If the latter, imaging is stopped after 30 sec (or earlier if the patient cannot hold the breath). ■ Washout (WO) phase: Dynamic views are obtained for 3–5 min. ▶ 99mTc-MAA perfusion imaging: 3–5 mCi ■ Static images in 6 or 8 standard projections, immediately after intravenous injection.

Findings ▶ V: Homogeneous ventilation (SB) with no regional air trapping (WO). ▶ Q: There are areas of mildly decreased activity corresponding to the heart, mediastinum, and aortic knob. Otherwise, perfusion in the lungs is homogeneous with no pleural-based, segmental defects.

Differential Diagnosis ▶ No scintigraphic finding to explain patient’s symptoms and positive D-dimer. Teaching Points ▶ A negative D-dimer has high negative predictive value for acute PE; a positive result does not exclude PE (specificity ~50%).

▶ A normal perfusion scan excludes clinically significant PE. ▶ 133Xe imaging is generally performed first due to its lower photon energy (81 keV vs. 99mTc’s 140 keV).

Although 133Xe images may be obtained after perfusion (only in projections showing abnormal Q), the quality of 133Xe images is poor due to 99mTc down-scatters. ▶ See updated SNM Practice Guideline (2012).

Management ▶ Typically, patient with suspected PE and normal perfusion scan can be managed safely without anticoagulation.

Further Readings Parker JA, et al. SNM Practice Guideline for Lung Scintigraphy, 4.0*. J Nucl Med. 2012;40:57–65. Schrecengost JE, et al. Comparison of diagnostic accuracies in outpatients and hospitalized patients of D-dimer testing for the evaluation of suspected pulmonary embolism. Clin. Chem. 2003;49:1483–1490.

64

Case 30 History ▶ Acute onset chest pain and shortness of breath.

Figure 30.1 

Figure 30.2 

65

Case 30  Pulmonary Embolism (PE) V

Q1

Q2

Figure 30.3 

Radiopharmaceutical/Dose/Procedure ▶ 99mTc-DTPA aerosol ventilation imaging: 30 mCi introduced into nebulizer with only 1–1.5 mCi actually

delivered to patient via a positive pressure nebulizer. ■ Count rate is continuously monitored in posterior projection during inhalation. ■ Patient breathes until the count rate from inhaled radioaerosol reaches 20%–30% of count rate expected from 99mTc-MAA (or count rate corresponding to 1–1.5 mCi). ■ Wipe the patient’s face and have him/her expel any saliva. ▶ 99mTc-MAA perfusion (Q) imaging: See Case 29.

Findings ▶ Panel V shows homogeneous ventilation and swallowed radioaerosol in the distal esophagus (arrows). ▶ Panel Q1 shows multiple mismatched, pleural-based, segmental perfusion defects, more extensive within the right lung.

Differential Diagnosis ▶ Findings typical of PE; cannot differentiate between acute and chronic PE based on a single study. Teaching Points ▶ PE typically causes V/Q mismatch (absent or decreased perfusion with preserved V). Perfusion defects are typically pleural based and wedge shaped.

▶ Following an acute pulmonary embolic event, the time required for clot resolution varies among patients and is affected by type of therapy, clot burden, and cardiopulmonary status of the patient.

▶ Resolution of perfusion defects following PE will typically occur within 3 months. ▶ Following 3 months, partially occlusive thrombus will become covered with endothelium and incorporated

within the vessel wall, causing narrowing of lumen. Once covered with endothelium, the thrombus typically does not undergo further lysis, resulting in chronic PE that causes permanent obstruction of the pulmonary arterial vasculature. ▶ Patient with high-burden chronic PE may develop pulmonary hypertension. ▶ Follow-up perfusion scan 3 months later (Panel Q2 in Figure 30.3) demonstrates persistent defects c/w chronic PE. ▶ See various interpretive criteria for PE summarized in updated SNM Practice Guideline (2012).

Management ▶ Anticoagulant therapy in most cases. ▶ Thrombolysis is considered in case of massive PE causing hemodynamic instability. ▶ Pulmonary thrombectomy may be performed in patients with chronic PE with pulmonary hypertension. Further Readings Parker JA, et al. SNM Practice Guideline for Lung Scintigraphy, 4.0*. J Nucl Med. 2012;40:57–65. Worsley et al. Radionuclide imaging of acute pulmonary embolism. Semin Nucl Med. 2003;33:259–278.

66

Case 31 History ▶ A 67-year-old man with acute onset shortness of breath

Figure 31.1 

Figure 31.2 

Figure 31.3 

67

Case 31  Chronic Obstructive Pulmonary Disease (COPD)

Figure 31.4 

Figure 31.5 

Radiopharmaceutical/Dose/Procedure: perfusion imaging (see Case 30).

99mTc-DTPA

Figure 31.6  aerosol ventilation imaging followed by 99mTc-MAA

Findings (Figures 31.1–31.5) ▶ Heterogeneous ventilation with numerous foci of aerosol clumping (Figure 31.4) and heterogeneous perfusion (Figure 31.5) within both lungs

▶ More prominent ventilation abnormalities compared with the perfusion abnormalities ▶ No pleural-based regions of V/Q mismatch ▶ Chest radiography: Hyperinflated lungs. Differential Diagnosis ▶ Reactive airway disease ▶ Diffuse airspace disease. Teaching Points ▶ COPD is associated with turbulent airflow and increased physiologic dead space, resulting in poor peripheral penetration and clumping of the radioaerosol.

▶ COPD produces multiple subsegmental or nonsegmental perfusion defects, which may be focal or diffusely

scattered throughout the lungs. However, perfusion abnormalities are generally less prominent than ventilation abnormalities. ▶ Reactive airway disease or diffuse airspace disease may be associated with a similar V/Q scan. However, reactive disease tends to produce more central deposition of aerosol in the large airway, as seen in Figure 31.6, rather than multiple foci of clumping distributed throughout the lungs, as seen in Figure 31.4. Correlation with clinical history and radiographic findings would be helpful to differentiate.

Management ▶ Treatment of COPD. Further Readings Mettler FA, Guiberteau MJ. Essentials of Nuclear Medicine Imaging. 5th ed. New York: Elsevier; 2006. Ziessman HA, et al. The Requisites Nuclear Medicine, 3rd ed. New York: Elsevier; 2006.

68

Case 32 History ▶ None.

Figure 32.1 Ventilation

ANT

POST

Figure 32.2 Perfusion

69

Case 32  Chronic Obstructive Pulmonary Disease (COPD) EQ

SB

WO 3

WO 1

WO 2

WO 4

ANT

Figure 32.3 

WO 1

POST

Figure 32.4 

WO 2

WO 3

Figure 32.5  Radiopharmaceutical/Dose/Procedure: 133Xe ventilation followed by 99mTc-MAA perfusion imaging (see Case 29).

Findings (Figures 32.3 and 32.4) ▶ Posterior 133Xe images (Figure 32.3) show markedly heterogeneous ventilation in both lungs. Tracer

distribution on the SB image and WO images is inversely correlated. ■ The most prominent defect on SB (representing worst V) in the right upper lobe fills in on EQ image and shows most delayed washout (dotted arrows). ■ Left lower lobe is best ventilated on SB and shows fastest washout (solid arrows). ■ The remaining lung regions also show inverse patterns on SB and WO. ▶ Figure 32.4: Distribution of perfusion is similar to that of SB.

Differential Diagnosis ▶ Findings typical of COPD. Teaching Points ▶ When perfusion defects are present, look for matching ventilation defects on SB and/or air trapping on WO. ■ Air trapping on WO is highly suggestive of obstructive airway process. However, defect on SB alone is not specific and may be caused by airway disease or other parenchymal process.

■ Perfusion defects matched with areas of air trapping make PE unlikely. ■ PE is not excluded when perfusion defects match with ventilation defects seen only on SB without air trapping on WO; in this case, chest radiograph or CT must be reviewed further.

■ EQ phase does not add more information to the evaluation of PE but is an important step necessary for WO

phase. Unless sufficient amount of 133Xe enters areas of obstructive airway disease during EQ phase, retention may not be well demonstrated during WO phase, which will make ventilation defects seen on SB nonspecific. ▶ See Case 31. ▶ 133Xe is fat-soluble. Delayed WO images occasionally show 133Xe activity in hepatic steatosis (Figure 32.5: an example of selected WO images from another patient). This may be confused with air trapping in the lung base, especially when hemidiaphragm is elevated.

Management ▶ Treatment of COPD. Further Reading Worsley DF, Kim CK. Ventilation/perfusion scanning in the diagnosis of acute pulmonary embolism. In Bahk YW, Kim EE, Isawa T, eds. Nuclear Imaging of the Chest. Berlin: Springer-Verlag; 1998:65–84.

70

Case 33 History ▶ None.

Ant

L Lat

R Lat

Post

LPO

RPO

Figure 33.1 

71

Case 33  Stripe Sign

Ant

L Lat

R Lat

Post

LPO

RPO

Figure 33.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MAA perfusion imaging (see Case 29).

Findings ▶ Peripheral rim or stripe of perfused lung interposed between the perfusion defect and the adjacent pleural surface (a.k.a. stripe sign) within both lower lobes.

▶ No pleural-based segmental perfusion defects. Differential Diagnosis ▶ COPD ▶ Any parenchymal disease.

Teaching Points ▶ Stripe sign is rarely due to PE and more commonly seen in patients with COPD or airspace disease. ▶ Stripe sign is one of the criteria for a very low probability of PE in PIOPED II. Others include nonsegmental

perfusion abnormalities; perfusion defect smaller than corresponding radiographic lesion; ≥ 2 matched V/Q defects with regionally normal chest radiograph and some areas of normal perfusion elsewhere in the lungs; 1–3 small segmental perfusion defects (< 25% of a segment); solitary triple matched defect in the middle or upper lung zone confined to a single segment; and pleural effusion equal to one-third or more of the pleural cavity with no other perfusion defect in either lung (Gottschalk et al. 2007). ▶ See various interpretive criteria for PE summarized in updated SNM Practice Guideline (2012).

Management (of Patients With Very Low or Low Probability V/Q Scan) ▶ In patients with very low or low probability V/Q scan and low clinical likelihood of PE, further investigation of PE or anticoagulation is generally unnecessary.

▶ Even in patients with intermediate to high clinical likelihood of PE, anticoagulation is generally not necessary if serial noninvasive venous studies of the lower extremities are negative.

Further Readings Gottschalk A, et al. Very low probability interpretation of V/Q lung scans in combination with low probability objective clinical assessment reliably excludes pulmonary embolism: data from PIOPED II. J Nucl Med. 2007;48:1411–1415. Parker JA, et al. SNM Practice Guideline for Lung Scintigraphy, 4.0*. J Nucl Med. 2012;40:57–65. Sostman HD, et al. Prospective validation of the stripe sign in ventilation-perfusion scintigraphy. Radiology. 1992;184(2):455–459.

72

Case 34 History ▶ Shortness of breath. Ventilation scan (not shown here) is normal.

ANT

LPO

POST

LT LAT

Figure 34.1 

73

Case 34 Pseudo-Stripe Sign; Single V/Q Mismatch on SPECT A

B

ANT

POST

C

Projection

V

Transaxial Q

LPO

LT LAT

Sagittal

Coronal

Figure 34.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MAA perfusion imaging (see Case 29).

Findings (Figure 34.2; panels A and B) ▶ Planar images (panel A) revealed a small defect with a stripe of activity on LPO and left lateral views (solid

arrows), which may represent a non-pleural-based defect. However, this defect is less well defined on anterior and posterior views, and the presence of “stripe sign” is uncertain. ▶ SPECT images (panel B) show a wedge-shaped pleural-based defect.

Differential Diagnosis ▶ Acute pulmonary embolus (PE) ▶ Chronic PE ▶ Other embolus, e.g., septic, air, fat ▶ Tumor occluding blood vessels. Teaching Points ▶ See Case 33. ▶ While unquestionable “Stripe Sign” is rarely due to PE, small perfusion defects with “stripe-like” surrounding

activity should be interpreted with caution, especially if the stripe is not clearly identified on the best tangential views (anterior and posterior views, in this case). ■ If there is any uncertainty as to whether the perfusion defect is real or not, or whether the defect is pleural or non-pleural based, consider SPECT perfusion imaging for further clarification. ▶ Single V/Q mismatch: ■ Intermediate probability of PE by most conventional criteria, including PIOPED and modified PIOPED criteria. ■ However, using PISAPED criteria (used primarily in Europe), “one or more wedge-shaped perfusion defects” without corresponding radiographic abnormalities is interpreted as “PE present.” ▶ See various interpretive criteria for PE summarized in updated SNM Practice Guideline (2012). ▶ SPECT (or SPECT/CT) imaging is becoming the norm in many centers, especially where 99mTc-technegas is available for ventilation imaging. An example is shown in Figure 34.2 (panel C). The selected set of images shows a mismatched perfusion defect in the lateral basal segment of the right lower lobe.

Management ▶ This patient had PE and received anticoagulation treatment. Further Readings Gutte H, et al. Detection of pulmonary embolism with combined ventilation–perfusion SPECT and low-dose CT: head-to-head comparison with multidetector CT angiography. J Nucl Med. 2009;12:1987–1992. Kim CK. Radiopharmaceuticals and imaging techniques: perfusion lung scanning. In: Bahk YW, et al., eds. Nuclear Imaging of the Chest. Berlin: Springer-Verlag; 1998:40–43. Parker JA, et al. SNM Practice Guideline for Lung Scintigraphy, 4.0*. J Nucl Med. 2012;40:57–65.

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Case 35 History ▶ Shortness of breath. Ventilation scan (not shown here) demonstrated a matched defect.

V

Q

LPO

Lt Lat

Figure 35.1 

Figure 35.2 

75

Case 35  Triple Match (V/Q Match With Radiographic Abnormality)

V

Q

LPO

Lt Lat

Figure 35.3 

Figure 35.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-DTPA aerosol ventilation imaging followed by 99mTc-MAA perfusion imaging (see Case 30).

Findings ▶ A moderate size segmental V/Q matched defect within the superior segment of the left lower lobe with corresponding abnormality on CT.

Differential Diagnosis for V/Q Scan Findings ▶ Pulmonary infarct ▶ Pneumonia ▶ Tumor. Teaching Points ▶ The term “triple match (3M)” refers to a moderate to large V/Q matching segmental defect with a corresponding radiographic abnormality of the same size and shape.

▶ In the PIOPED study, a 3M was associated overall with a 26% probability of PE. Upon further detailed analysis divided by lung zones, a 3M isolated in the upper/middle zones represented a low probability (11%–12%), while that in the lower zone represented an intermediate probability (33%). However, it should be noted that chest X-ray was employed in the PIOPED investigation, not CT. Therefore, the decision for further evaluation or treatment should be based on the most likely diagnosis based on CT findings. ▶ Upon further detailed analysis divided by the degree of perfusion, a 3M associated with merely “decreased” perfusion is less likely to represent PE than a 3M associated with “absent” perfusion. For example, the low probability of PE associated with all 3Ms in the upper/middle zones became 0% instead of 11%–12% if perfusion was merely decreased, whereas the probability of PE increased to 25% (intermediate) if perfusion was absent. Likewise, the intermediate probability associated with all 3Ms in the lower zone went down from 33% to 18% if perfusion was merely decreased, whereas it increased to high-intermediate probability, i.e., 63% (intermediate), if perfusion was absent.

Management ▶ The patient in this case had PE and received anticoagulation. Further Readings Kim CK, Worsley DF, Alavi A. Ventilation/perfusion/chest radiography match is less likely to represent pulmonary embolism if perfusion is decreased rather than absent. Clin Nucl Med. 2000;25:665–669. Worsley DF, Kim CK, Alavi A, Palevski HI. Detailed analysis of patients with matched ventilation-perfusion defects and chest radiographic opacities. J Nucl Med. 1993;34:1851–1853.

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Case 36 History ▶ A 54-year-old woman with shortness of breath.

V

Q

V

Q

Figure 36.1 

77

Case 36  Reverse V/Q Mismatch

Figure 36.2  Radiopharmaceutical/Dose/Procedure: 99mTc-DTPA aerosol ventilation imaging followed by 99mTc-MAA perfusion imaging (see Case 30).

Findings ▶ Top row: ■ Ventilation in the left lower lobe is absent. ■ Swallowed radioaerosol in the stomach during inhalation. ■ Renal activity due to renal clearance of 99mTc-DTPA aerosol absorbed into the blood from lung. ▶ Bottom row: Perfusion in the left lower lobe is markedly decreased (arrows) but is better than ventilation abnormality.

Differential Diagnosis (reverse mismatch in a single region, usually seen in the lung base or entire lower lobe) ▶ Bronchial obstruction, e.g., mucous plug ▶ Bronchial obstruction, e.g., endobronchial lesion ▶ Large pleural effusion ▶ Pneumonia. Teaching Points ▶ Reverse V/Q mismatch refers to a ventilation defect worse than corresponding perfusion defect, where perfusion may be decreased or normal when compared with the rest of the lungs. Even though perfusion is moderately to markedly decreased, these findings should be interpreted as a “reverse mismatch” rather than a match. ▶ Reverse mismatch in a single area in one lung is most commonly seen in the lung base or entire lower lobe. In acute setting, it is generally related to bronchial obstruction (e.g., mucous plug), large pleural effusion, pneumonia, or any combination of these conditions. ▶ Reverse mismatch is highly unlikely to represent PE, even if perfusion is decreased.

Management ▶ Varies depending on the cause of reverse mismatch. Further Readings Carvalho P, Lavender JP. The incidence and etiology of the ventilation/perfusion reverse mismatch defect. Clin Nucl Med. 1989;14:571–576. Shah RM, et al. Reverse ventilation/perfusion (V/Q) mismatch as a cause of hypoxemia. Am J Respir Crit Care Med. 181;2010:A6073.

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Case 37 History ▶ A 3-month-old infant with respiratory distress.

LPO

Q

V

RPO

Q

V

Figure 37.1 

79

Case 37 Shunting of Perfusion Through Atelectatic Lower Lobes Due to PEEP

LPO

Q

V

RPO

Q

V

Figure 37.2 

Figure 37.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-MAA perfusion imaging followed by 81mKr (krypton-81m) ventilation imaging acquired during continuous inhalation of approximately 1–10 mCi.

Findings ▶ Ventilation and perfusion show a completely opposite pattern: ■ Ventilation in both lower lobes is absent, while perfusion is greater in the lower lobes than in the upper and middle lobes.

▶ Extra-pulmonary MAA activity consistent with known congenital heart disease with R-L shunt. ▶ CT: bilateral lower lobe atelectasis. Differential Diagnosis ▶ Atelectasis (with ineffective positive pressure ventilation support). Teaching Points ▶ Pulmonary perfusion is determined by pulmonary arterial/venous pressure (Pa/Pv) and alveolar pressure

(Palv). In normal upright lungs, perfusion is less in the apical/upper zone than in lower zone because perfusion in the apex occurs only at the peaks of the pulsatile Pa wave that exceeds Palv, whereas perfusion in the lower zone is normally not affected by Palv because Pa/Pv exceeds Palv. The findings in this case are uncommon but illustrate the effect of artificially elevated airway pressure. ▶ Atelectasis is a common cause of reverse V/Q mismatch (see also Case 36). However, perfusion in most cases of reverse mismatch is decreased or normal at best, but not increased as seen in this case. ▶ This infant with lobar atelectasis was placed on positive end-expiratory pressure (PEEP) support in order to re-expand collapsed lower lobes. It was unsuccessful. Further, PEEP caused increased airway pressure (hence increased resistance to Q) in well-ventilated upper and middle lobes, which in turn caused shunting of perfusion to atelectatic lower lobes unaffected by PEEP (i.e., R-L shunt). ▶ 81mKr is obtained from an 81Rb/81mKr (currently unavailable in the US). 81mKr imaging can be performed after perfusion imaging due to its 191-keV photopeak, allowing imaging only in the projections showing perfusion abnormalities. Further, each set of V/Q images can be acquired individually without moving the patient owing to 81mKr’s extremely short physical half-life (13 sec), e.g., in the order of Q1, V1, Q2, V2, etc.

Management ▶ Ineffective PEEP was discontinued, and the patient’s condition improved. Further Reading Kim CK, Heyman S. Ventilation/perfusion mismatch caused by positive pressure ventilatory support. J Nucl Med. 1989;30:1268–1270.

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Case 38 History ▶ A 62-year-old man with dyspnea and hemoptysis.

Figure 38.1 

Figure 38.2 

81

Case 38 Unilateral V/Q Mismatch Due to Centrally Located Tumor V

Q

Ant

Figure 38.3 

LAO

Post

RPO

Figure 38.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-DTPA aerosol ventilation imaging followed by 99mTc-MAA perfusion imaging (see Case 30).

Findings ▶ Figure 38.1: Heterogeneous ventilation in both lungs. Decreased ventilation in the left lung. ▶ Figure 38.2: Absent perfusion in the left lung that is more severe than the ventilation abnormality (V/Q mismatch). Normal perfusion in the right lung.

▶ Figure 38.3: CT shows encasement of the left pulmonary artery and vein by a soft tissue mass with small left pleural effusion. The left lower lobe bronchus is compressed but not completely occluded.

Differential Diagnosis for V/Q Scan Findings ▶ Extrinsic compression of the pulmonary artery or vein (centrally located tumor/lymphadenoapthy) ▶ Unilateral pulmonary artery hypoplasia or agenesis ▶ MAA injection into a misplaced central line ▶ Fibrosing mediastinitis ▶ PE causing absent perfusion in an entire lung is statistically extremely rare. Therefore, clinical correlation (with other imaging and/or history) is necessary.

Teaching Points ▶ Unilateral V/Q mismatch is not a typical pattern of PE. ▶ Perfusion imaging provides an indirect assessment of pulmonary perfusion and patency of the pulmonary artery.

▶ Any process extrinsic to the pulmonary artery, such as lung cancer or lymphadenopathy, that compresses the vessel wall or that involves the vessel, such as sarcoma or vasculitis, may cause decreased perfusion.

▶ Other causes of decreased perfusion to one lung include pneumonectomy. ▶ Hilar tumor may cause more severe ventilation abnormality than perfusion abnormalitys. ■ V/Q findings in a patient with known hilar tumor (Figure 38.4: companion case) suggest that the tumor

is obstructing the right main stem bronchus and right upper and middle lobar arteries, but that the lower lobar artery is spared.

Management ▶ Further management appropriate for cancer stage. Further Readings Pickhardt PJ, et al. Unilateral hypoperfusion or absent perfusion on pulmonary scintigraphy: differential diagnosis. AJR. 1998;171:145–150. Worsley DF, et al. Radionuclide imaging of acute pulmonary embolism. Semin Nucl Med. 2003;33:259–278.

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Case 39 History ▶ A 24-year-old woman who is 4 days postpartum with acute onset shortness of breath.

Ventilation

Perfusion

Figure 39.1  Chest X-ray on the same day.

Figure 39.2 

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Case 39  Pulmonary Embolism (PE)

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Figure 39.4 

Figure 39.3  Radiopharmaceutical/Dose/Procedure: perfusion imaging (see Case 30).

99mTc-DTPA

Figure 39.5 

aerosol ventilation imaging followed by 99mTc-MAA

Findings ▶ Figure 39.3: ■ V/Q mismatches in the anterior segment of the left upper lobe (A), lateral basal segment of the left lower lobe (B), superior segment of the right lower lobe (C), and the entire right upper lobe (D).

■ Activity in the thyroid and lactating breast (top panel), likely due to presence of free pertechnetate in 99mTc-DTPA

■ Renal activity due to both DTPA and pertechnetate. ▶ Figure 39.4: Normal chest radiograph performed on the same day. ▶ Figure 39.5: Follow-up radiograph 24 hours later demonstrated a wedge-shaped pleural-based opacity

(Hampton hump) within the right upper lobe. The perfusion abnormality within the right upper lobe was more extensive than the radiographic opacity.

Teaching Points ▶ See Case 30: pulmonary embolism. ▶ See Case 38: large hilar tumor. ▶ 2 or more large mismatched segmental defects or the equivalent in moderate defects (2 moderate equals one large) indicate “high” probability interpretation with PPV of 88%.

▶ When the perfusion defect is substantially larger than the radiographic abnormality, the probability of PE

is high. Perfusion defect that corresponds closely in size to an airspace opacity carries an “intermediate” probability, and if clinical suspicion is high, further evaluation (e.g., CT angiography) may be indicated. ▶ Published data suggest a 12-hour interruption of breastfeeding for subjects receiving 4 mCi of 99mTc-MAA, but no interruption is needed for 99mTc-DTPA, 133Xe, 99mTc-technegas, or 81mKr (see SNM Practice Guideline). ▶ See various interpretive criteria for PE summarized in updated SNM Practice Guideline (2012).

Management ▶ Anticoagulation ▶ Regarding breastfeeding: ■ Before scan: It is advised to express and store breast milk, if possible, to feed baby later. ■ After scan: As a rule of thumb, it is advised to stop breastfeeding for approximately 24 hours. Further Readings Parker JA, et al. SNM Practice Guideline for Lung Scintigraphy, 4.0*. J Nucl Med. 2012;40:57–65. Worsley DF, et al. Radionuclide imaging of acute pulmonary embolism. Semin Nucl Med. 2003;33:259–278.

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Case 40 History ▶ Shortness of breath.

LPO

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Figure 40.1  Single breath 133Xe V 75 61

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Figure 40.2 Perfusion

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Case 40  Attenuation Artifact Due to Arms

LPO

RPO

Figure 40.3  75 61

64

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Figure 40.4  Radiopharmaceutical/Dose/Procedure: 133Xe ventilation followed by 99mTc-MAA perfusion imaging (see Case 29).

Findings ▶ Figure 40.3: Apparently decreased ventilation in the anterior portion of both lungs, which is sharply demarcated and traversing through lobes.

▶ Figure 40.4: Heterogeneous perfusion without mismatched defect. Differential Diagnosis ▶ Findings on ventilation scan are typical of attenuation artifact due to overlying arms. Teaching Points ▶ In this case, the artifact on ventilation scan was noted before perfusion imaging was started. The patient was instructed to raise the arms during perfusion imaging.

▶ If the patient is unable to raise the arms for medical reasons (e.g., stroke, orthopedic problem, etc.) or is not instructed to do so, similar defects may be seen on perfusion imaging.

Management ▶ Technologist who performed this study was reminded of the importance of adhering to the imaging protocol.

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Case 41 History ▶ A 54-year-old man with acute onset shortness of breath.

Figure 41.1 

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Case 41  Hot Spots Due to Clumping of MAA Particles

Figure 41.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MAA perfusion imaging (see Case 29).

Findings ▶ Perfusion scan demonstrates multiple foci of increased activity randomly distributed throughout the lungs. ▶ No pleural-based segmental perfusion defects. Differential Diagnosis ▶ None. Teaching Points ▶ Clumping of particles within the syringe or injection of small labeled clot can lead to multiple focal hot spots scattered throughout the lungs.

▶ This pattern is typically caused by mixing blood in the syringe prior to injection, clumped particles within the syringe due to inadequate mixing, or thrombophlebitis of the injected vein.

▶ If possible, blood should not be drawn back into the syringe at the time of injection. Management ▶ None. Further Readings Ikehira H, et al. Hot spots observed on pulmonary perfusion imaging: a case report. J Nucl Med Technol. 1999;27:301–302. Worsley DF, et al. Radionuclide imaging of acute pulmonary embolism. Semin Nucl Med. 2003;33:259–278.

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Part 4

Pediatric Nuclear Medicine Phillip J. Koo, Frederick D. Grant, S. Ted Treves

Case 42 History ▶ A 55-day-old girl with jaundice.

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Figure 42.2 

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Case 42  Biliary Atresia

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Figure 42.3 

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Figure 42.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-mebrofenin/0.02 mCi/kg; minimum 0.5 mCi/Hepatobiliary scan, dynamic imaging for 1 hour after intravenous injection and delayed static images at 24 hours.

Findings ▶ Prompt and homogeneous hepatic uptake of tracer ▶ No excretion in the extrahepatic ducts or bowel after up to 24 hours ▶ Non-visualized gallbladder ▶ Relatively increased renal excretion of tracer, reflecting increased excretion through an alternative excretory pathway Differential Diagnosis ▶ Impaired biliary excretion ■ Extrahepatic: biliary atresia, bile duct obstruction ■ Intrahepatic: paucity of bile ducts (Alagille syndrome), intrahepatic cholestasis ▶ Hepatocellular dysfunction: neonatal hepatitis, total parenteral nutrition syndrome ▶ Systemic: dehydration, sepsis. Teaching Points ▶ Biliary excretion of tracer into the bowel, if present, is evidence of an intact biliary system and excludes the diagnosis of biliary atresia with a sensitivity and negative-predictive value of virtually 100%.

▶ The reported specificity ranges from 43% to 90%. With hepatocellular dysfunction, there is a structurally

intact biliary system that allows for excretion of the radiotracer into the bowel. However, tracer excretion into the bowel may not be discernible with severe hepatocellular dysfunction, especially on early imaging. ▶ Delayed imaging can be helpful, particularly if bile production is diminished due to the hepatocellular dysfunction. ▶ Pretreatment with phenobarbital for 3–5 days, by enhancing bile synthesis and flow, may increase the specificity and positive-predictive value of the study. ▶ Urine activity in the diaper or urine contamination of the skin of the abdomen on delayed images should not be confused with intestinal activity. Acquiring delayed images after cleaning the skin and changing the diaper can prevent this from occurring.

Management ▶ Definitive diagnosis of biliary atresia is usually made by percutaneous or operative transhepatic cholangiography. ▶ Early diagnosis of biliary atresia is important because surgical intervention is most successful during the first few weeks of life.

Further Reading Kim CK, et al. Liver and biliary tract. In: Elgazzar A, ed. The Pathophysiologic Basis of Nuclear Medicine. 2nd ed. Berlin: Springer-Verlag; 2006:419–447. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:213–217.

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Case 43 History ▶ A 16-year-old girl.

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Figure 43.2 

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Case 43  Choledochal Cyst (Type I) 0 min

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Figure 43.4 

Figure 43.3 

Figure 43.5 

Figure 43.6 

Radiopharmaceutical/Dose/Procedure: 99mTc-mebrofenin/ 0.02 mCi/kg; maximum 1.4 mCi / Hepatobiliary scan, dynamic imaging for 1 hour after intravenous injection and delayed static images as needed.

Findings ▶ During the first 60 minutes of imaging (Figure 43.3), there is prompt hepatic uptake and clearance of tracer. There is tracer accumulation in the dilated extrahepatic duct (arrow) and prompt excretion into the bowel.

▶ After the intravenous administration of morphine with administration of a small booster dose of 99mTc-mebrofenin

(Figure 43.4), there is prompt filling of the gallbladder (arrow).

▶ Ultrasound and MRI (Figures 43.5 and 43.6) confirm the findings of fusiform dilatation (arrow) of the extrahepatic bile duct.

Differential Diagnosis ▶ Cholecystitis is suggested by delayed gallbladder filling; could be chronic but not acute given the fact that there is prompt filling of the gallbladder after administration of morphine.

▶ Obstruction of the distal common bile duct could be considered, but prompt excretion of radiotracer into the bowel and decreasing CBD activity (45–60 minutes) makes this unlikely.

Teaching Points ▶ Todani classification of choledochal cysts: ■ Type I: Saccular or fusiform dilatation of the extrahepatic duct ■ Type II: Diverticulum ■ Type III: Choledochocele ■ Type IV: Multiple dilatations of the biliary duct

◆ IVA involves intra- and extrahepatic ducts. ◆ IVB involves only the extrahepatic duct. ■ Type V (Caroli disease): Multiple dilatations of the intrahepatic ducts ▶ On hepatobiliary imaging, choledochal cysts often appear photopenic early in imaging, and later fill as radiotracer progresses through the biliary system. ▶ Some centers administer a booster dose of radiotracer at the time of morphine administration if little activity remains in the liver parenchyma.

Management ▶ Due to potential complications, such as obstruction or stasis, extrahepatic choledochal cysts typically are removed surgically.

Further Readings Kim OH, Chung HJ, Choi BG. Imaging of the choledochal cyst. Radiographics. 1995;15:69–88. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:219–220.

Case 44 History ▶ A 5-year-old boy with rectal bleeding.

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Figure 44.1 

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Case 44  Ectopic Gastric Mucosa in a Meckel Diverticulum

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Figure 44.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sodium pertechnetate/0.05 mCi/kg; minimum 0.02 mCi / Meckel scan, dynamic imaging for 30 minutes after intravenous injection and additional static images as needed.

Findings ▶ Dynamic images of the torso show focal uptake in the right lower quadrant that accumulates in parallel with uptake in the stomach and does not migrate during the period of imaging.

Differential Diagnosis ▶ In the setting of gastrointestinal bleeding, this most likely represents ectopic gastric mucosa in a Meckel diverticulum, or less likely in a duplication cyst.

▶ Pertechnetate accumulation also can occur in neoplasms and inflammatory bowel disease. ▶ Attention to the time pattern of tracer accumulation and additional views may be helpful to exclude urinary tracer accumulation.

Teaching Points ▶ Approximately half of all Meckel diverticula contain ectopic gastric mucosa, which can cause bleeding due to acid-induced damage of adjacent mucosa.

▶ Other complications of Meckel diverticula include obstruction, diverticulitis, intussusception, and perforation. ▶ Pentagastrin and glucagon have been reported to help improve the accuracy of this study; however, these are rarely used and are not required. Compared to these two drugs, cimetidine has been more commonly used to improve the accuracy, but it also is used infrequently. ▶ When dynamic imaging appears negative with a high clinical suspicion for Meckel diverticulum, lateral planar images or SPECT (or SPECT/CT, if available) may be helpful.

Management ▶ Symptomatic Meckel diverticula are resected. ▶ Treatment of an asymptomatic diverticulum is controversial. Further Readings Levy AD, Hobbs CM. Meckel diverticulum: radiologic features with pathologic correlation. Radiographics. 2004;24:565–587. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:192–200.

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Case 45 History ▶ A 14-month-old boy with recurrent pneumonia.

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Figure 45.1 

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Case 45  Tracheobronchial Aspiration

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Figure 45.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sulfur colloid/0.3 mCi/Radionuclide salivagram is performed by administering 99mTc-sulfur colloid in a drop of saline at the back of or under the tongue. Dynamic imaging is performed in the posterior projection.

Findings ▶ Rapid transit of tracer from the oropharynx to the stomach (dotted arrow) ▶ Rapid accumulation of tracer within the tracheobronchial tree, extending into branching bronchi (arrow) ▶ No spontaneous clearance of the aspirated radiopharmaceutical. Differential Diagnosis ▶ This pattern of tracer accumulation is diagnostic of tracheobronchial aspiration. ▶ Careful attention should be paid to determine whether the aspiration originated from oropharyngeal contents or was a result of gastroesophageal reflux.

Teaching Points ▶ Salivagram is a physiologic technique that assesses for aspiration of oral secretions in patients with recurrent pulmonary infections.

▶ The radionuclide salivagram is more sensitive for the detection of pulmonary aspiration than the upper GI exam or swallowing studies, which involve the conscious swallowing of liquids and solids.

▶ Compared to contrast radiograph studies, salivagram provides less anatomic detail, but has a lower radiation dose.

▶ Aspiration is more common from the oropharynx rather than from reflux. Management ▶ Aspiration to the proximal tracheobronchial tree often is cleared rapidly by the mucociliary epithelium. ▶ Distal aspiration to branching bronchi does not spontaneously clear and often requires medical or even surgical intervention.

▶ Serial follow-up with salivagrams is often preferred over fluoroscopy due to reduced radiation dose. Further Readings Grant FD. Nuclear medicine and molecular imaging of the pediatric chest: current practical imaging assessment. Radiol Clin North Am. 2011;49:1025. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:181–183.

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Case 46 History ▶ A 3-year-old boy.

Figure 46.1 

Figure 46.2 

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Case 46  Non-Obstructive Hydronephrosis

Figure 46.3  Radiopharmaceutical/Dose/Procedure: 99mTc-MAG3/0.1mCi/kg; minimum 1 mCi/Diuretic renogram, initial dynamic imaging for 20–30 minutes before furosemide administration, followed by additional dynamic imaging for 20–30 minutes after furosemide administration.

Findings ▶ Figure 46.1: ■ Mild pelvicaliectas in the left kidney, as demonstrated by decreased cortical uptake near the hilum ■ Cortical transit time (defined as the time of appearance of tracer in the renal collecting system) = 4 minutes (normal < 6 minutes)

■ Markedly delayed spontaneous drainage of the left collecting system ■ No ureteral dilation or tortuosity.

▶ Figure 46.2 (after intravenous injection of furosemide 1 mg/kg): ■ Substantial tracer washout from the renal collecting system ■ Quantitative assessment: Washout half-time (T1/2) is 11 minutes with a 30-minute residual of 23%, which are considered intermediate parameters for evaluation of obstruction.

▶ Figure 46.3: Ultrasound of the left kidney shows mild pelvicaliectasis.

Differential Diagnosis ▶ Rapid uptake and clearance of tracer from the renal cortex indicates intact perfusion and cortical function. Pelvicaliectasis and delayed clearance of tracer from the collecting system suggest hydronephrosis.

▶ The diuretic phase is important to confirm the presence or absence of clinically important collecting system obstruction.

Teaching Points ▶ The pattern of the initial 20-minute time-activity curve is nonspecific, and examination of the dynamic images is necessary to differentiate cortical dysfunction and collecting system obstruction.

▶ Delayed tracer excretion from the renal collecting system with absence of tracer accumulation in a dilated or tortuous ureter suggests mild obstruction at the ureteropelvic junction (UPJ).

▶ Diuresis parameters, such as renal washout T1/2 and post-diuresis residual, are helpful to assess the degree of obstruction.

▶ Important causes of prolonged washout T1/2 without obstruction include poor renal function, markedly dilated collecting system/renal pelvis, chronic use of furosemide, and full bladder.

Management ▶ Patients with intermediate parameters for obstruction are often followed closely for the worsening or resolution of hydronephrosis.

▶ Renal cortical scintigraphy (99mTc-DMSA) can be used to more accurately assess differential renal function. Further Readings Ross SS. Observation of infants with SFU grades 3-4 hydronephrosis: worsening drainage with serial diuresis renography indicates surgical intervention and helps prevent loss of renal function. J Pediatr Urol. 2011;7:266–271. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:251–257.

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Case 47 History ▶ A 40-day-old girl.

Figure 47.1 

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Case 47  Multicystic Dysplastic Kidney

Figure 47.2 

Figure 47.3  99mTc-DMSA/0.05

Radiopharmaceutical/Dose/Procedure: scintigraphy, static imaging at 4 hours after injection.

mCi/kg; minimum 0.02 mCi/Renal cortical

Findings ▶ Figure 47.2: The right kidney is reniform in shape and in the expected location. No functional renal cortex is seen in the expected location of the left kidney.

▶ Figure 47.3: Ultrasound shows that the left kidney is replaced by multiple cysts of varying sizes with no areas of normal renal tissue identified.

Differential Diagnosis ▶ Differential diagnosis of the renal cortical scan alone includes: ■ Multicystic dysplastic kidney (MCDK) ■ Polycystic kidney disease ■ Renal agenesis ■ Ectopic kidney. ▶ The ultrasound findings are typical of MCDK, and are unlikely to represent polycystic kidney disease in a child this age.

Teaching Points ▶ MCDK typically presents as a unilaterally small, cystic kidney and often is diagnosed in utero. Bilateral MCDK is incompatible with life. Polycystic kidneys are usually bilateral and enlarged.

▶ If there is a clinical suspicion for an ectopic kidney, the field of view of the DMSA scan should be expanded to include the pelvis.

Management ▶ The non-functioning kidney can be removed if symptomatic; otherwise no further intervention is required. Further Readings Katabathina VS, Kota G, et al. Adult renal cystic disease: a genetic, biological, and developmental primer. Radiographics. 2010;30(6):1509–1523. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:267.

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Case 48 History ▶ A 10-year-old girl with recurrent febrile urinary tract infections.

Figure 48.1 

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Case 48  Vesicoureteral Reflux (RNC-Grade 3)

Figure 48.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sodium pertechnetate/1 mCi/Direct radionuclide cystogram (RNC). ▶ After the direct infusion of tracer into the bladder through a urethral catheter, dynamic images were obtained in the posterior projection.

Findings ▶ Starting at 5 minutes, there is reflux of radiotracer into the left ureter, which transits into the dilated renal collecting system. This would be designated RNC-grade 3 vesicoureteral reflux (VUR).

Differential Diagnosis ▶ There is no differential diagnosis. The specific cause of reflux, however, cannot be determined on this examination. Teaching Points ▶ In RNC, reflux severity is graded on a scale of 1 (reflux into a ureter), 2 (reflux into renal collecting system), and 3 (reflux with collecting system dilation), while in VCUG severity is graded I–V.

▶ RNC has higher sensitivity than VCUG for detection of VUR, as dynamic images can be acquired over a longer period of time and contrast resolution is higher with RNC than with VCUG.

▶ The anatomic resolution of RNC is lower than VCUG; thus evaluation for ureteroceles, bladder diverticula, or posterior urethral valves should be performed by other studies, such as VCUG or ultrasound.

▶ The radiation exposure with RNC is 50–100 times lower than with VCUG.

Management ▶ The natural progression of low-grade VUR includes spontaneous resolution. ▶ Urinary tract infection in the setting of VUR can be associated with pyelonephritis and renal scarring, with a risk of renal failure. Early intervention is required.

▶ Management can include observation, chronic antibiotic prophylaxis, or surgical correction of VUR. Persistent or severe VUR will require surgical intervention.

▶ Given the lower degree of radiation exposure, RNC also is the preferred study for follow-up imaging and for screening asymptomatic siblings of children with VUR.

Further Reading Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:286–304.

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Case 49 History ▶ A 5-year-old girl.

ANTERIOR

ANTERIOR with transmission

RIGHT LATERAL

RIGHT LATERAL with transmission

Figure 49.1 

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Case 49  Lingual Thyroid

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Figure 49.2 

RIGHT LATERAL

RIGHT LATERAL with transmission

Figure 49.3 

Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide/0.006 mCi/kg; minimum 0.025 mCi/Thyroid scan, 4 hours and 24 hours after oral administration.

Findings ▶ Figure 49.2: Planar images of the upper body show a solitary focus of iodine uptake in the midline near the base of the tongue, which is consistent with a lingual thyroid. ■ No other sites of iodine-avid tissue are identified. ■ A Cobalt-57 flood source was used to produce transmission images to aid in localization (lower panels). ▶ Figure 49.3: Ultrasound images confirm the absence of thyroid tissue in the thyroid bed.

Differential Diagnosis ▶ None. The thyroid scan is diagnostic for ectopic thyroid tissue. Teaching Points ▶ Lingual thyroid is caused by arrested descent of the thyroid gland during embryogenesis. Ectopic thyroid tissue can be located anywhere along the thyroglossal duct tract.

▶ Patients with an ectopic thyroid typically have hypothyroidism, but can have normal thyroid function. ▶ Physical examination may find an exophytic mass at the base of the tongue, but additional imaging or biopsy is not required. A lingual thyroid can cause dysphagia, respiratory obstruction, or pain.

Management ▶ Thyroid hormone replacement is indicated in hypothyroid patients. ▶ Symptoms related to the lingual thyroid size can be treated with thyroid hormone suppression or with surgical resection.

▶ Patients treated surgically will require lifelong thyroid hormone replacement. Further Reading Rahbar R, Yoon MJ, Connolly LP, et al. Lingual thyroid in children: a rare clinical entity. Laryngoscope. 2008;118:1174–1179.

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Case 50 History ▶ A 9-month-old boy with excessive crying.

Figure 50.1 

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Case 50  Non-Accidental Trauma (Child Abuse)

Figure 50.2  Radiopharmaceutical/Dose/Procedure: 18F-sodium fluoride/0.06 mCi/kg; minimum 0.3 mCi/Whole body bone PET imaging, 30–45 minutes after injection.

Findings ▶ This is a maximum intensity projection (MIP) image from an 18F-sodium fluoride PET, not a 99mTc-MDP bone scan. ▶ There is increased uptake in the distal right radius, mid- and proximal left humerus, and distal right tibia. ▶ There is abnormal uptake in multiple right anterior and left anterolateral ribs. ▶ Uptake in the left distal radius/hand is due to partial infiltration of the radiopharmaceutical. Differential Diagnosis ▶ The pattern of findings is highly suspicious for child abuse and requires further evaluation before other diagnoses are considered.

▶ Accidental trauma, disseminated infection, or metastatic disease could be the cause of multiple sites of uptake. However, the location and distribution in this case is highly specific for child abuse.

Teaching Points ▶ Imaging plays a central role in the identification and evaluation of non-accidental trauma. ▶ Characteristic sites of fracture include the skull, ribs, long bones, and metaphyseal corner fractures; multiple fractures of varying age are very suspicious for child abuse.

▶ Bone scans are complementary to radiographs, such as whole body skeletal surveys. Bone scans may be less

sensitive for classic metaphyseal fractures and skull fractures, but are more sensitive for detection of rib fractures.

▶ 18F-sodium fluoride PET is an alternative method of bone scan that can have higher image quality and improved accuracy compared to 99mTc-MDP bone scans.

Management ▶ Bone scan findings should be correlated with radiographs. ▶ Findings should be clearly documented in the report and directly communicated to the referring clinician by the interpreting physician.

Further Readings Drubach LA, et al. Skeletal trauma in child abuse: detection with 18F-NaF PET. Radiology. 2010;255:173–181. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:345–349.

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Case 51 History ▶ A 8-year-old boy.

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Figure 51.1 

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Case 51  Ischiopubic Synchondrosis

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Figure 51.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; minimum 1 mCi/Bone scan.

Findings ▶ Increased uptake at the left ischiopubic junction ▶ The adjacent bones are normal. Differential Diagnosis ▶ The main differential would be osteomyelitis. ▶ In a patient with a known primary malignancy, metastatic disease would be a consideration, but it would be unusual to have a solitary lesion in the pelvis.

Teaching Points ▶ Ischiopubic synchondrosis ■ Is the cartilaginous junction between the inferior pubic ramus and ischium. ■ Typically ossifies between 4 and 12 years of age. ■ On bone scan, uptake in the ischiopubic synchondrosis is often asymmetric. ▶ Septic arthritis typically has increased uptake in both bones surrounding a joint. Management ▶ This is a normal variant and requires no further workup. ▶ Familiarity with the appearance will help avoid unnecessary additional imaging and/or intervention. Further Reading Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:318–321.

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Case 52 History ▶ A 8-year-old girl.

Figure 52.1 

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Case 52  Polyostotic Fibrous Dysplasia

Figure 52.2 

Figure 52.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; minimum 1 mCi/Whole body bone scan/

Findings ▶ Bone scan shows multiple sites of increased non-focal uptake throughout the axial and appendicular skeleton,

including the frontal and occipital bones, right mandible, both humeri, right ulna, left proximal radius, right hemipelvis, both femurs, both tibiae, and both fibulae. ▶ Radiograph of the pelvis demonstrates mild expansion of the right proximal femur with a ground glass matrix and early development of varus angulation.

Differential Diagnosis ▶ Other possible diagnoses could include: ■ Metastatic disease ■ Disseminated infection ■ Osseous lymphoma. ▶ However, the widespread pattern of non-focal uptake is most characteristic of polyostotic fibrous dysplasia. Teaching Points ▶ Abnormal areas of uptake on bone scan should be correlated with radiographs to help determine the etiology.

Fibro-osseous lesions with an expansile, ground glass appearance on radiographs help to confirm the diagnosis.

▶ Fibrous dysplasia can be mono-ostotic or polyostotic. ▶ McCune-Albright syndrome consists of at least two of the following: polyostotic fibrous dysplasia, café au lait spots, and autonomous endocrine hyperfunction.

Management ▶ Patients with McCune-Albright syndrome should be followed closely by an endocrinologist for evaluation and management of endocrine hyperfunction.

Further Readings Shore EM. Inherited human diseases of heterotopic bone formation. Nat Rev Rheumatol. 2010;6:518–527. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:367–373.

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Case 53 History ▶ An 11-year-old boy with back pain. Top

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Case 53  Osteoid Osteoma Top

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Figure 53.2  Radiopharmaceutical/Dose/Procedure: scan with SPECT.

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Figure 54.4 

mCi/kg; minimum 1 mCi; maximum 20 mCi/Bone

Findings ▶ Figure 53.2: Intense focal uptake in the left posterior elements, probably at the lamina/pedicle junction, of vertebra T12.

Differential Diagnosis ▶ In the setting of suspected osteoid osteoma, intense uptake on bone scan/SPECT often helps establish the

diagnosis and location of the lesion. However, bone scan/SPECT is nonspecific for increased bone turnover, which also could reflect infection, neoplasm, metabolic disorders, or trauma.

Teaching Points ▶ Patients with osteoid osteoma often present with bone pain that is worse at night or with activity and that is relieved with NSAIDs.

▶ Bone scan is sensitive for osteoid osteoma. SPECT is particularly beneficial for evaluating lesions involving the spine.

▶ Bone scan can define the anatomic region for further evaluation with CT or MRI. ▶ CT can be used to confirm the diagnosis of osteoid osteomas and guide management. Management ▶ Patients are referred for either surgery or radiofrequency ablation for symptomatic relief. ▶ In surgical patients, 99mTc-MDP can be administered preoperatively, and a mobile gamma camera used intraoperatively to confirm complete surgical resection of the lesion.

▶ Pinhole images from an intraoperative bone scan (Figure 53.3) demonstrate resection of the focus of uptake with radioactivity, now only identified in the postoperative specimen (Figure 53.4). The symptoms resolved after surgery.

Further Readings Blackiewicz DJ. Osteoid osteomas: interoperative bone scan-assisted resection. J Neurosurg Pediatr. 2009;4:237–244. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:362–366.

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Case 54 History ▶ An 11-year-old boy.

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Figure 54.1 

Figure 54.2 

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Case 54 Osteomyelitis

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Figure 54.3 

Figure 54.4 

Figure 54.5  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; minimum 1 mCi/Whole body bone scan, 2–3 hours after injection.

Additional History and Findings ▶ Bone scan (Figures 54.1–54.5) was performed in an 11-year-old boy who presented with pain, swelling, and erythema around the right ankle.

▶ In the right tibia, there is a decreased uptake in the distal third (Figure 54.5; small arrows) and subtly increased uptake in the mid-shaft (thick arrows).

Differential Diagnosis ▶ In this clinical presentation, these findings are most consistent with osteomyelitis. ▶ Osteonecrosis and bone infarct also could present as a photopenic defect. Teaching Points ▶ Osteomyelitis most often occurs in long bones, typically at the metaphyses, which are highly vascularized. ▶ Osteomyelitis is most often “hot” and rarely “cold” on bone scan. “Cold” lesions likely reflect increased

intraosseous pressure due to inflammation. A rim of increased uptake in adjacent bone represents increased bone turnover in reaction to the infection. ▶ Septic joints often demonstrate increased uptake in the periarticular bones on both sides of the joint space.

Management ▶ Antibiotic therapy is indicated. Given the proximity to the joint, careful evaluation (such as ultrasound or joint aspiration) should be performed for septic joint.

▶ Antibiotic therapy will not immediately affect bone scan findings, and should not be held if the bone scan will be delayed.

Further Reading Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:322–343.

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Case 55 History ▶ A 3-year-old boy with a limp.

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Case 55  Perthes Disease

Figure 55.4  Figure 55.5  Figure 55.6  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; minimum 1 mCi/Three phase bone scan with pinhole images.

Findings ▶ Figure 55.1 (angiographic-phase): Symmetric perfusion in the lower extremities. ▶ Figures 55.2 and 55.4 (tissue-phase): Relative photopenia over the right hip (arrow in Figure 55.4). ▶ Figure 55.3 (skeletal-phase pinhole images): Decreased uptake in the head of the right femur and a normal pattern of uptake in the head of the left femur.

▶ Figure 55.5: While the pinhole image of the right hip demonstrates decreased uptake in the medial aspect of

the right femoral epiphysis (thick arrow), uptake along the lateral aspect of epiphysis (thin arrow) indicates an early stage of revascularization. ▶ Figure 55.6: Three months later, a follow-up radiograph shows the right femoral epiphysis to be small, flattened, and sclerotic, consistent with Perthes disease.

Differential Diagnosis ▶ Typical appearance of avascular necrosis (AVN) of the femoral head ▶ Causes of AVN of the femoral head include: ■ Idiopathic (Legg-Calve-Perthes disease, also called Perthes disease) ■ Secondary: ◆ Sickle cell disease ◆ Gaucher disease ◆ Glucocorticoid use ◆ Radiation therapy. ■ Traumatic

Teaching Points ▶ Perthes disease is an idiopathic AVN of the capital femoral epiphysis; the typical presentation is a young boy who presents with a limp.

▶ Over 90% of cases of Perthes disease are unilateral. If there is bilateral involvement, secondary AVN of the femoral head is much more likely.

▶ Bone scan is indicated when radiographs are negative and there remains a concern for AVB. Skeletal-phase pinhole imaging is highly recommended as it increases the accuracy of the exam.

Management ▶ Perthes disease is a self-healing disorder, and treatment focuses on allowing the femoral head to reossify in a

spherical fashion within the acetabulum. This requires containment of the femoral head within the acetabulum.

▶ Nonsurgical therapies include immobilization or range of motion exercises, while surgical options include femoral or acetabular osteotomies.

Further Readings Connolly LP. Skeletal symptoms in the multimodality assessment of young children with acute skeletal symptoms. Clin Nucl Med. 2003;28:746. Treves ST. Pediatric Nuclear Medicine/PET. New York: Springer; 2007:343.

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Case 56 History ▶ A 4-year-old girl with fever and lassitude.

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Figure 55.1 

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Case 56 Neuroblastoma

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Figure 55.2  Radiopharmaceutical/Dose/Procedure: after administration.

Figure 55.3  123I-MIBG/0.14

mCi/kg; minimum 1 mCi/whole body imaging at 1 day

Findings ▶ MIBG images: ■ Physiological uptake in salivary glands (not shown), myocardium, and liver is typical of an MIBG scan. ■ A large region of heterogeneous uptake in the pelvis is concerning for a soft tissue tumor. ■ Widespread osseous metastases are identified by numerous sites of intense focal uptake in the pelvis and extremities in a pattern that likely reflects focal skeletal uptake.

▶ On CT, a large retroperitoneal mass contaning punctate calcifications corresponds to abnormal 123I-MIBG uptake.

Differential Diagnosis ▶ Tumors of neural crest origin, e.g., neuroblastoma, pheochromocytoma, and gangioglioma, demonstrate increased MIBG uptake.

▶ In a child, a large MIBG-avid abdominal mass with skeletal metastases is most likely neuroblastoma. ▶ Localizing the sites of uptake is often challenging and can be improved with SPECT and correlation/ co-registration with CT or MR.

Teaching Points ▶ 123I-MIBG is highly accurate for the diagnosis and follow-up of patients with neoplasms originating from

neural crest cells. 18F-FDG PET can be an alternate imaging method, particularly in patients with low stage disease. ▶ Physiological uptake of 123I-MIBG can be seen in salivary glands, heart, lung, liver, adrenal glands, and brown adipose tissue. Excreted MIBG may accumulate in the bladder and bowel. ▶ Multiple staging classifications are used for neuroblastoma. Most common is the International Neuroblastoma Staging System, which is a postsurgical staging system. ▶ Stage 4S includes infants less than 12–18 months of age with localized disease and dissemination limited to skin liver, and/or bone marrow.

Management ▶ Treatment options include surgery, chemotherapy, radiation, and radiotherapy with 131I-MIBG. ▶ Close observation may be an option, especially in infants with stage 4S disease. ▶ Patients are often monitored with 123I-MIBG exams during and after therapy. Further Readings Grant FD. Nuclear medicine and molecular imaging of the pediatric chest: current practical imaging assessment. Radiol Clin North Am. 2011;49:1025. Lonergan GJ, et al. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: Radiologic-pathologic correlation. Radiographics. 2002;22:911–934. Sharp S. Diagnosis of neuroblastoma. Sem Nucl Med. 2011;41:345–353.

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Case 57 History ▶ A 4-year-old girl.

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Figure 57.1 

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Case 57 Left Pulmonary Artery Atresia (Previously Treated) With a Right-to-Left Cardiac Shunt

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Figure 57.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MAA/0.05 mCi/kg; minimum 0.2 mCi/Imaging immediately after injection.

Findings ▶ There is decreased relative perfusion to the left lung compared to the right lung. In this patient with a history

of congenital heart disease, these findings are the result of left pulmonary artery atresia previously treated with unifocalization and multiple dilatations. ▶ Mild systemic penetration of tracer, demonstrated by tracer accumulation elsewhere in the body, especially in the kidneys.

Differential Diagnosis ▶ Findings are diagnostic of a right-to-left (pulmonary-to-systemic) shunt. ■ In the setting of congenital heart disease, the most likely cause is an intracardiac defect. ■ Intrapulmonary shunts will have a similar appearance on perfusion scan. Teaching Points ▶ Uptake in the brain, kidneys, liver, spleen and/or thyroid is indicative of a right-to-left shunt that allows the particles to bypass the pulmonary circulation and enter the systemic circulation.

▶ For quantitative assessment of the shunt, anterior and posterior whole body imaging may be necessary. ▶ 99mTc-MAA perfusion scan is sensitive for the detection of right-to-left shunts, and the degree of systemic penetration is proportional to the severity of the shunt.

Management ▶ For future perfusion lung scans, the administered number of MAA particles should be reduced in order to minimize systemic microembolization.

▶ If clinically indicated, dedicated cardiac imaging could be performed. Further Readings Grant FD. Nuclear medicine and molecular imaging of the pediatric chest: current practical imaging assessment. Radiol Clin North Am. 2011;49:1025. Mettler FA, Guiberteau MJ. Essentials of Nuclear Medicine. Philadelphia: Elsevier; 2006:147.

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Case 58 History ▶ A 7-year-old female dancer.

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Case 58 Bilateral Pars Stress in Vertebra L4 With Spondylolysis Confirmed on CT

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Figure 58.3 

Figure 58.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; minimum 1 mCi, maximum 20 mCi/Bone scan with SPECT, 2–3 hours after injection.

Findings ▶ Planar images (Figure 58.3) show increased uptake bilaterally in the lower lumbar spine. ▶ SPECT images (Figure 58.2) demonstrate that the uptake is located in both pars interarticulares of vertebra L4. ▶ CT (Figure 58.4) shows bilateral pars defects, indicating bilateral L4 spondylolysis. Differential Diagnosis ▶ Increased uptake in a pars interarticularis can indicate stress changes, but does not distinguish stress changes from fracture (spondylolysis).

▶ Facet arthropathy may appear similar, but is more common in older adults. Teaching Points ▶ Bone scan is highly sensitive for stress changes in the pars interarticulares. ▶ Bone scan is more sensitive for the detection of early stress changes than spine radiographs, CT, or MRI. ▶ SPECT is much more sensitive than planar imaging and should be performed in all children suspected of having pars stress.

▶ Bone scan does not distinguish stress changes from fracture (spondylolysis). Management ▶ Patients identified with pars stress changes typically are instructed to temporarily discontinue related physical activities and may be prescribed a back brace. In most cases, symptoms improve or resolve.

▶ If symptoms persist despite rest or bracing, CT can be used to differentiate pars stress from pars fracture (spondylolysis).

▶ The CT can be localized to the vertebra of interest (identified by bone scan) to reduce radiation exposure. Further Reading Zukotynksi K, et al. Skeletal scintigraphy in pediatric sports medicine. AJR 2010;195:1212.

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Case 59 History ▶ A 17-year-old female soccer player.

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Case 59  Stress Fracture

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Radiopharmaceutical/Dose/Procedure: 99mTc-MDP/0.2 mCi/kg; maximum 20 mCi/Three phase bone scan.

Findings ▶ Figure 59.1: Dynamic angiographic phase images acquired immediately after tracer administration show symmetrical perfusion in the pelvis and proximal legs.

▶ Figure 59.4: Planar tissue-phase images acquired soon after the angiographic images show minimally increased activity (arrows) corresponding to the ovoid focus of increased uptake noted on the skeletal-phase images.

▶ Figure 59.5: Skeletal-phase images acquired 3–4 hours after tracer administration show an ovoid focus of increased uptake in the medial aspect of the diaphysis of the left femur.

Differential Diagnosis ▶ Fatigue/overuse stress changes present as a spectrum of severity from minor stress changes, to stress fractures, to acute fracture.

▶ The differential also includes apophysitis at the adductor insertion and traumatic fracture. ▶ Osteoid osteoma or healing non-ossifying fibroma might have a similar appearance. Teaching Points ▶ Stress fractures typically have focal uptake on skeletal-phase images while non-fractured stress changes typically have diffuse linear uptake.

▶ In the legs, stress fractures occur most commonly in the tibia, but also can occur in the fibula or femur.

With stress fractures, focal tracer accumulation may or may not be seen on angiographic or tissue phase of a bone scan. ▶ Soft tissue accumulation typically is more focal than the pattern of soft tissue accumulation seen with an inflammatory process. ▶ Two types of stress fracture: ■ Fatigue stress fracture: Normal bone exposed to abnormal stresses ■ Insufficiency stress fracture: Abnormal bone exposed to normal stresses ▶ Scintigraphic findings should be correlated with available anatomic imaging.

Management ▶ Activity modification is required, which often includes activity restriction or rest for 4–12 weeks. ▶ Stress fractures left untreated can lead to worsening pain and eventual fracture of the involved bone. Further Readings Anderson MW. Stress fractures. Radiology. 1996;199:1–12. Hutchinson PH. Complete and incomplete femoral stress fractures in the adolescent athlete. Orthopedics. 2008;31:604.

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Part 5

Nuclear Cardiac Imaging Balaji Rao, Marcelo F. Di Carli

Case 60 History ▶ A 44-year-old male with atypical chest pain was referred for exercise myocardial perfusion SPECT scan.

Figure 60.1 

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Case 60  Reporting of Exercise Myocardial Perfusion Imaging (MPI)

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Technique: (1) Rest imaging ~30 minutes after IV injection of 8–10 mCi of 99mTc-sestamibi, (2) exercise and inject 25–30 mCi of 99mTc-sestamibi IV at peak stress, and (3) stress imaging (including gated imaging at 8 frames per cardiac cycle) 15–45 minutes after tracer injection. Findings: Normal (Figure 60.2) Differential Diagnosis: None

Teaching Points Report should contain the following, in addition to the clinical history and procedure details: ▶ Location of the defects (based on AHA/ACC 17 segment model) (Figure 60.3) ▶ Size of the defects—small: 1–2 segments; medium: 3–4 segments; large: ≥ 5 ▶ Severity of the defects—normal perfusion: 0; mild reduction in counts: 1; moderate reduction in counts: 2; severe reduction in counts: 3; absent count: 4 ▶ Semiquantitative evaluation of regional myocardial perfusion. For example, current procedure guidelines from the American Society of Nuclear Cardiology advocate the use of global scores: summed stress score (SSS, reflecting the total extent and severity of perfusion deficit during stress), summed rest scores (SRS, reflecting the total extent and severity of perfusion deficit at rest), and summed difference score (SDS, reflecting the total magnitude of defect reversibility or ischemia). ▶ Type of the defects (reversible, fixed, mixed) ▶ Presence of single or multi-vessel disease ▶ Categorization of ischemia based on SDS as: ■ mild (1–3), moderate (4–7), and severe (>7) ▶ Markers of severe ischemia such as: ■ ST segment ECG changes during stress ■ Transient LV cavity dilatation (transient ischemic dilatation) between stress and rest images ■ Increased lung uptake (particularly with thallium). ▶ Semi-quantitative scoring of gated wall motion on the SPECT and PET-CT as: normal: 0; mild hypokinesis: 1; moderate hypokinesis: 2; severe hypokinesis: 3; akinesis: 4; and dyskinesis: 5 ▶ Presence of significant extracardiac activity or lesion on nuclear tomogram or on attenuation correction CT. Further Reading http://www.asnc.org/imageuploads/PP-Reporting080309.pdf.

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Case 61 History ▶ A 70-year-old male with central chest pain, who was unable to exercise due to severe osteoarthritis, underwent regadenoson pharmacological stress SPECT scan.

Figure 61.1 

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Case 61  Normal Pharmacological Stress MPI

Figure 61.2  Technique: (1) NPO > 4 hours, withhold β-blocker on the day of the test, and withhold caffeinated beverages for 24 hours; (2) rest imaging 30–40 minutes after IV injection of 99mTc-sestamibi 8–10 mCi; (3) pharmacologic stress using one of the agents as described in Teaching Points; (4) IV injection of 99mTc-sestamibi 25–30 mCi at peak hyperemia; and (5) stress imaging (including gated imaging at 8 frames per cardiac cycle) 45 minutes after tracer injection. Findings: Normal Differential Diagnosis: None

Teaching Points ▶ Symptom limited exercise stress test is always preferred. It is safe, most physiological, inexpensive, and provides additional hemodynamic data that has important prognostic implications.

▶ However, one must avoid submaximal exercise because it reduces test sensitivity for detection of obstructive CAD.

▶ Pharmacologic stress is an important alternative in patients unable to exercise. ■ Vasodilator agents approved for pharmacologic stress testing:

◆ Adenosine (administered at 140 mcg/kg/min for 4–6 minutes) ◆ Dipyridamole (administered at 142 mcg/kg/min for 3–6 minutes) ◆ Regadenoson (administered as 400 mcg bolus over 10 seconds). ■ Catecholamines: Dobutamine. It is administered at increments of 10 mcg/kg/min until target heart rate or a maximum dose of 40 mcg/kg/min is achieved, whichever comes first. For patients unable to reach target heart rate at peak dobutamine infusion, atropine 0.25–2 mg can be administered. ▶ Contraindications to vasodilator pharmacological stress agents are: ■ The use of fioricet/migraine medications with caffeine ■ The use of aggrenox/oral dipyridamole within last 48 hours ■ The use of theophylline/aminophylline ■ The use of caffeine (coffee, tea, soda, chocolate) within last 12–24hrs ■ Lung Disease (severe asthma/COPD) ▶ Contraindications to dobutamine pharmacological stress agents are: ■ Dobutamine: aortic aneurysm and VT/AICD ■ Atropine: prostatism and glaucoma. Further Readings http://www.asnc.org/imageuploads/PP-Regadenoson092309.pdf. http://www.asnc.org/imageuploads/PP-Adenosine092309.pdf.

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Case 62 History ▶ A 65-year-old female with known 3-vessel coronary artery disease was referred for exercise MIBI scan 6 months following right coronary artery (RCA) stent.

Figure 62.1 

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Case 62  Abnormal Exercise MPI

Figure 62.2  Technique: See Case 60.

Findings Figure 62.1 (MPI): ▶ Small-sized defect of mild intensity in the apical inferior segment in resting images ▶ Large-sized completely reversible defect of severe intensity in the mid-anteroseptal wall, apical anterior wall, septum, and true apex in stress images ▶ Normal perfusion in the LCx and RCA territories in both resting and stress images. Figure 62.2 (selective RAO view of the left coronary system): ▶ A total occlusion of the mid LAD coronary artery ▶ A moderate stenosis in the mid-portion of the left circumflex artery without an associated perfusion abnormality on MPI.

Differential Diagnosis ▶ Breast attenuation artifact. Teaching Points ▶ Myocardial perfusion imaging with SPECT/PET is useful for follow-up of patients with coronary artery disease and provides important therapeutic and prognostic information.

Management ▶ The extent and severity of myocardial ischemia on SPECT help guide management. The current guidelines suggest that revascularization may offer prognostic advantage in the presence of ischemia > 10% of the left ventricle, as in this case.

Further Reading Hachamovitch R, Rozanski A, Shaw LJ, et al. Impact of ischaemia and scar on the therapeutic benefit derived from myocardial revascularization vs. medical therapy among patients undergoing stress-rest myocardial perfusion scintigraphy. Eur Heart J. 2011;32:1012–1024.

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Case 63 History ▶ A 46-year-old male with known coronary artery disease and atypical chest pain was referred for regadenoson PET-CT.

Figure 63.1  Polar maps

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Figure 63.2 

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Case 63 Infarction in the Obtuse Marginal and Posterior Descending Artery (PDA) Territory Polar maps Basal

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Figure 63.3 

Figure 63.4 

Technique: (1) NPO > 4 hours; (2) Scout CT acquisition for patient positioning followed by CT transmission scan for attenuation correction; (3) rest emission scan 90 seconds after completion of IV infusion of 82Rb 50 mCi at rest (including gated imaging at 8 frames per cardiac cycle); (4) repeat imaging using one of the pharmacologic stress protocols as described in Case 61 with the same CT parameters and 82Rb dosage used for resting study.

Findings ▶ A small-sized fixed defect in the basal lateral wall, typically supplied by the left circumflex artery. ▶ A small-sized fixed defect in the mid-inferior and apical inferior segments, typically suplied by posterior descending artery.

▶ Akinesis of the mid- and apical inferior segments and severe hypokinesis of the basal and mid-anterolateral segments on cine images.

Differential Diagnosis ▶ Hibernating myocardium. Teaching Points ▶ Myocardial perfusion imaging is useful to detect infarction and ischemia in patients with stable CAD. ▶ In the setting of severe fixed perfusion defects, additional imaging with FDG may be helpful to delineate residual hibernating myocardium. Please refer to Case 65.

Management ▶ In patients with known stable coronary artery disease, an infarction without significant ischemia warrants maximal medical therapy for secondary prevention.

Further Reading Hachamovitch R, Rozanski A, Shaw LJ, et al. Impact of ischaemia and scar on the therapeutic benefit derived from myocardial revascularization vs. medical therapy among patients undergoing stress-rest myocardial perfusion scintigraphy. Eur Heart J. 2011;32:1012–1024.

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Case 64 History ▶ A 47-year-old male with no known coronary artery disease was referred for regadenoson stress PET-CT to evaluate arrhythmias.

Figure 64.1 

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Case 64 Mild Ischemia in the LAD Territory With Transient Ischemic Dilatation (TID)

Figure 64.2  Technique: See Case 63.

Findings ▶ Medium-sized completely reversible perfusion defect of moderate intensity in the apical septal segment, apical inferior segment, mid-inferior segment, and true apex segment (Figure 64.1)

▶ Severe transient ischemic dilatation (TID) during stress, with a calculated TID ratio of 1.46 (Figure 64.2) (reference: normal TID ratio for PET ≤ 1.1)

▶ Calculated myocardial flow reserve of 0.96 (reference: normal ≥ 2, abnormal ≤ 2) Differential Diagnosis ▶ Multi-vessel CAD. Teaching Points ▶ 82Rb is a generator-produced PET myocardial perfusion imaging agent. ▶ Advantages of PET MPI over SPECT include more accurate attenuation correction, improved image quality, lower radiation, and the ability to estimate coronary flow reserve.

▶ The presence of a perfusion defect, TID, and severe reduction in coronary flow reserve in this patient are consistent with severe multi-vessel coronary artery disease.

▶ All these markers are associated with high clinical risk.

Management ▶ Coronary angiography to determine the extent and severity of obstructive CAD and possible revascularization.

Further Readings Di Carli MF, Murthy VL. Cardiac PET/CT for the evaluation of known or suspected coronary artery disease. Radiographics. 2011 Sep–Oct;31(5):1239–1254. Weiss A, Berman D, Lew A, et al. Transient ischemic dilation of the left ventricle on stress thallium-201 scintigraphy: a marker of severe and extensive coronary artery disease. J Am Coll Cardiol. 1987;9:752–759.

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Case 65 History ▶ A 59-year-old female with known CAD and low ejection fraction referred for myocardial viability assessment by PET.

Rb-82 FDG-18 Rb-82 FDG-18 Rb-82 FDG-18 Rb-82 FDG-18

Figure 65.1 

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Case 65  Hibernating Viable Myocardium in the LAD Territory SA

HLA

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Rb-82

FDG-18

Figure 65.2  Technique: See Case 63.

Findings ▶ Large perfusion defect in the basal anterior, mid-anterior, mid-anteroseptal, apical anterior, apical septal, and true apical segments in the typical distribution of the LAD

▶ Preserved FDG uptake in all hypoperfused segments (perfusion-metabolic mismatch) consistent with viable but hibernating myocardium in the distribution of the LAD.

Differential Diagnosis ▶ Myocardial infarction. Teaching Point ▶ Perfusion/metabolism mismatch suggests viable myocardium. Management ▶ Hibernating myocardium may recover function with revascularization therapy. Further Readings Abraham A, Nichol G, Williams KA, et al. 18F-FDG PET imaging of myocardial viability in an experienced center with access to 18F-FDG and integration with clinical management teams: the Ottawa-FIVE Substudy of the PARR 2 Trial. J Nucl Med. 2010;51:567–574. Buckley O, Di Carli M. Predicting benefit from revascularization in patients with ischemic heart failure: imaging of myocardial ischemia and viability. Circulation. 2011 Feb 1;123(4):444–450.

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Case 66 History ▶ A 50-year-old female with heart block was referred for cardiac PET scanning to evaluate for possible cardiac sarcoidosis.

Figure 66.1 

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Case 66  Cardiac Sarcoid Post-steroid therapy

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Figure 66.2 

Background of Perfusion-Metabolism Imaging in the Assessment of Cardiac Sarcoid ▶ The basic rationale for FDG PET imaging in cardiac sarcoidosis is that macrophages and other leukocytes present during the active phase of inflammatory processes are FDG avid.

▶ Because normal myocardium is also FDG avid, the use of FDG PET in cardiac sarcoidosis requires suppression of FDG uptake by normal myocytes.

▶ Patients are typically instructed to have a high-fat, low-carbohydrate diet to increase circulating free fatty acid levels to force a switch from glucose to free fatty acid use by normal myocytes.

▶ Imaging technique: See Case 63.

Findings ▶ Pretreatment Rb-82: Small perfusion defect of severe intensity involving the basal anteroseptal and inferoseptal segments

▶ Pretreatment FDG: Increased FDG uptake in the corresponding basal anteroseptal and inferoseptal segments, suggestive of active inflammation

▶ Post-treatment FDG: Resolution of increased FDG uptake Differential Diagnosis ▶ Other forms of myocardial inflammation (e.g., myocarditis). Teaching Point ▶ Perfusion-metabolism mismatch suggests active sarcoid granulomas. Management ▶ FDG PET CT can be used to guide biopsy of the cardiac/extra-cardiac tissue. ▶ Cardiac and extra-cardiac sarcoid are treated with systemic steroids and other immunosuppresants. ▶ Serial metabolic imaging can be used to monitor disease activity. Further Readings Blankstein R, Osborne M, Naya M, Waller A, Kim CK, Murthy VL, Kazemian P, Kwong RY, Tokuda M, Skali H, Padera R, Hainer J, Stevenson WG, Dorbala S, Di Carli MF. Cardiac positron emission tomography enhances prognostic assessments of patients with suspected cardiac sarcoidosis. J Am Coll Cardiol. 2013 Oct 1. doi:pii: S0735-1097(13)05455-7. Yamagishi H, Shirai N, Takagi M, et al. Identification of cardiac sarcoidosis with 13N-NH3/18F-FDG PET. J Nucl Med. 2003;44:1030–1036.

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Case 67 History ▶ A 67-year-old female with lymphoma was referred for equilibrium radionuclide ventriculogram to quantify cardiac function prior to chemotherapy.

Figure 67.1 

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Case 67 Incorrectly Placed Background Activity Overlapping With Spleen

Figure 67.2  Technique: Radionuclide ventriculogram is performed with 99mTc-labeled RBC (20-30 mCi) and ECG gating.

Findings ▶ Normal left ventricle size and function. ■ Figure 67.1: The calculated ejection fraction using incorrectly placed background activity overlapping with spleen is 67%.

■ Figure 67.2: The calculated ejection fraction using the correct background activity is 63%.

▶ Normal right ventricle size with normal regional and global function.

Teaching Points ▶ Qualitative and quantitative information are best obtained in left anterior oblique view. ▶ Automated computerized edge detection is more accurate as it is based on a mathematical model and not on visual discrimination.

▶ Incorrect placement of background activity can artificially elevate the calculated ejection fraction. ▶ Background activity should be placed close to the left ventricle without overlapping the atrium, ventricles, spleen, aorta, aneurysm, or other blood pool structure.

▶ Report should show global and regional ejection fractions, end-diastolic (ED) and end-systolic (ES) frames of the cardiac cycle, and the size, shape, and location of the background region of interest.

Further Reading http://www.asnc.org/imageuploads/ImagingGuidelineERNA.pdf.

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Case 68 History ▶ A 41-year-old female with no known CAD was referred for an exercise treadmill myocardial perfusion SPECT study to evaluate for chest pain and palpitations.

Figure 68.1 

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Case 68  Normal Study—Breast Attenuation Artifact

Stress

Rest

Figure 68.2  Technique: See Case 60.

Findings ▶ Stress and rest perfusion images show a fixed, small-sized mild perfusion defect in the apical and mid-anterior segments.

▶ Gated cine images show no associated wall motion abnormalities (not shown). ▶ Tomogram shows overlying breast shadow (not shown). Differential Diagnosis ▶ Ischemia ▶ Infarction ▶ Motion artifact. Teaching Points ▶ Typical location of perfusion defect in the anterior segment in a female should raise the possibility of breast attenuation artifact.

▶ Review of tomogram and gated cine images can help in differentiating artifact from true defect. ▶ In difficult cases, PET-CT can differentiate breast attenuation artifact from true perfusion defect. Management ▶ Medical management of coronary risk factors. Further Reading Fleischmann S, Koepfli P, Namdar M, Wyss CA, Jenni R, Kaufmann PA. Gated 99mTc-tetrofosmin SPECT for discriminating infarct from artifact in fixed myocardial perfusion defects. J Nucl Med. 2004;45:754–759.

146

Case 69 History ▶ A 79-year-old male with no known coronary artery disease was referred for the evaluation of

cardiomyopathy. He underwent regadenoson PET-CT myocardial perfusion study. Resting ECG showed left bundle branch block.

Figure 69.1 

147

Case 69 Fixed Septal Perfusion Defect Due to Left Bundle Branch Block 27

Stress

25

Rest

Figure 69.2  Technique: See Case 60.

Findings ▶ Small-sized fixed defects of severe intensity in the basal anteroseptal, basal inferoseptal, mid-anteroseptal and mid-inferoseptal segments (Figures 69.1 and 69.2)

▶ Normal perfusion in the remainder of the myocardial segments ▶ No evidence of vasodilator stress-induced perfusion defect ▶ Gated cine images show global hypokinesis with LVEF of 25% (not shown). Differential Diagnosis ▶ Myocardial infarction. Teaching Points ▶ Isolated basal and mid-septal fixed perfusion defects in a non-coronary artery distribution is consistent with left bundle branch block.

▶ Septal perfusion defect is thought to result from reduced diastolic time in the interventricular septum due to the delayed activation in LBBB.

Management ▶ Patients with cardiomyopathy with LVEF < 35% and left bundle branch block should be considered for

automated internal cardioverter defibrillator (AICD) with or without cardiac resynchronization therapy (CRT) to prevent sudden cardiac death.

Further Reading Higgins JP, Williams G, Nagel JS, Higgins JA. Left bundle-branch block artifact on single photon emission computed tomography with technetium Tc 99m (Tc-99m) agents: mechanisms and a method to decrease false-positive interpretations. Am Heart J. 2006;152:619–626.

148

Case 70 History ▶ A 53-year-old-male with no known coronary artery disease was referred for myocardial perfusion PET study as part of a research. His risk factors include hypertension, diabetes, and obesity.

Figure 70.1 

149

Case 70  Motion Artifact (Hurricane Sign) Repeat stress

Stress Rest

Figure 70.2  Technique: See Case 60.

Findings ▶ Figure 70.1: Initial stress images demonstrate abnormal perfusion in the anterior and inferior segments at all levels. Appearances are suspicious for movement artifact, which is characteristically described as “hurricane sign.” ▶ Figure 70.2: Repeat testing suggests normal perfusion.

Differential Diagnosis ▶ Coronary artery disease. Teaching Points ▶ Perfusion defects with smudged margins extending beyond the contours of myocardium are highly suggestive of movement artifact.

Management ▶ None Further Reading Sorrell V, Figueroa B, Hansen CL. The “hurricane sign”: evidence of patient motion artifact on cardiac single-photon emission computed tomographic imaging. J Nucl Cardiol. 1996;3:86–88.

150

Case 71 History ▶ A 76-year-old male with dyspnea was referred for regadenoson myocardial perfusion PET CT to assess for myocardial ischemia.

Figure 71.1 

151

Case 71  Non-Ischemic Dilated Cardiomyopathy 210

LV Vol (ml)

168

126

84 GStr GRst EDV: 175 165 ml ESV: 125 140 ml

42

EF: 0

28 15

1

% 3

5

7

9

Gating Frame Figure 71.2  Technique: See Case 61.

Findings ▶ Normal myocardial perfusion with no evidence of ischemia or scar ▶ Severely dilated left ventricle ▶ LVEF of 15% at rest (Figure 71.2) increased to 28% on vasodilator stress test. Differential Diagnosis ▶ None Teaching Points ▶ Myocardial perfusion imaging can identify ischemia and infarction, thereby reliably distinguishing non-ischemic from ischemic cardiomyopathy.

Management ▶ Medical management: A normal study can avoid an unnecessary coronary angiogram. Further Reading Danias PG, Ahlberg AW, Clark BA, 3rd, et al. Combined assessment of myocardial perfusion and left ventricular function with exercise technetium-99m sestamibi gated single-photon emission computed tomography can differentiate between ischemic and nonischemic dilated cardiomyopathy. Am J Cardiol. 1998;82:1253–1258.

152

Case 72 History ▶ A 61-year-old female was referred for rest equilibrium radionuclide ventriculography to evaluate regional and global cardiac function following doxorubicin chemotherapy.

Figure 72.1 

153

Case 72 Doxorubicin Cardiotoxicity—Decreased Left Ventricle Function

Figure 72.2  Technique: Radionuclide ventriculogram is performed with 99mTc-labeled RBC (20-30 mCi) and ECG gating.

Findings ▶ Dilated left ventricle with septal and apical akinesis. Left ventricle ejection fraction (LVEF) calculated at 38% (Figures 72.1 and 72.2).

▶ Normal right ventricular size with normal regional and global function. Differential Diagnosis ▶ ECG gating issues, which can underestimate LVEF. Teaching Points ▶ Left ventricle ejection fraction (LVEF) is the most important prognostic factor and predictor of future major adverse cardiac events (MACE).

▶ Radionuclide ventriculogram is a noninvasive and reproducible way for estimating left ventricular ejection fraction.

▶ Early drop in LVEF due to chemotherapy can be detected on serial imaging before clinical manifestations and irreversible cardiac damage occur.

Management ▶ Drop in LVEF, even if subclinical, necessitates change to noncardiotoxic chemotherapy agents. Further Reading Fatima N, Zaman Mu, Hashmi A, Kamal S, Hameed A. Assessing adriamycin-induced early cardiotoxicity by estimating left ventricular ejection fraction using technetium-99m multiple-gated acquisition scan and echocardiography. Nuclear Med Commun. 2011;32:381–510.

154

Case 73 History ▶ A 68-year-old male with no known coronary artery disease was referred to exercise myocardial perfusion SPECT study for atypical chest pain.

Figure 73.1 

155

Case 73  Diaphragmatic Attenuation Artifact

Repeat PET CT Stress Rest

Figure 73.2 

Figure 73.3 

Technique: See Case 60.

Findings ▶ Figure 73.2: SPECT images demonstrate fixed perfusion defects involving the basal inferior segment. Differential Diagnosis ▶ Myocardial infarction ▶ Diaphragmatic attenuation. Teaching Points ▶ SPECT attenuation artifacts are typically seen in the inferior segments. ▶ Use of attenuation correction CT decreases the likelihood of SPECT artifact. ▶ Review of gated cine images can be helpful. ▶ In difficult cases, PET/CT myocardial perfusion can be used for further characterization. In this patient, a repeat regadenoson myocardial perfusion PET/CT showed normal perfusion (Figure 73.3).

Management ▶ None Further Reading Fricke E, Fricke H, Weise R, et al. Attenuation correction of myocardial SPECT perfusion images with low-dose CT: evaluation of the method by comparison with perfusion PET. J Nucl Med. 2005;46:736–744.

156

Part 6

Bone Scintigraphy Sherif Heiba, Chun K. Kim

Case 74 History ▶ A 55-year-old woman with newly diagnosed breast cancer had a bone scan for staging.

Figure 74.1 

159

Case 74  Paget Disease A

B

C

D

E

Figure 74.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Diffusely increased uptake in L3 vertebra (arrow, Mickey Mouse appearance) and right hemipelvis (Figures 74.1 and 74.2A).

▶ Characteristic appearance of facet osteoarthritis (dotted arrow in Figure 74.2A); see Further Readings. Differential Diagnosis ▶ Bone metastases ▶ Primary bone malignancy (e.g., osteosarcoma, Ewing sarcoma) ▶ Fibrous dysplasia. Teaching Points ▶ Paget disease: ■ Affects 3%–4% of population > age 40 and up to 10%–11% > age 80 ■ Monostotic in 10%–35% of cases (more often in axial skeleton) and polyostotic in 65%–90% ■ Vertebrae (30%–75%), pelvis (30%–75%), skull (25%–65%) and proximal long bones (25%–30%). ▶ Scintigraphic findings vary with different radiographic phases: ■ Lytic phase: Tracer uptake may be increased and/or decreased. Areas of aggressive bone resorption may

display relative photopenia; this pattern is often seen in skull (osteoporosis circumscripta) (Figure 74.2C).

■ Fibrous phase: Markedly increased uptake in the involved areas. Bone scan is more sensitive than radiograph; can be used to document the effectiveness of therapy.

■ Sclerotic phase: Uptake is less intense than in fibrous phase and may return to normal.

▶ In vertebrae, the transverse and spinous processes are frequently involved in addition to vertebral body, producing a characteristic “Mickey Mouse (or Mouse Face)” appearance (Figures 74.2A and 74.2B).

▶ In long bones, disease begins in subchondral area of the epiphysis and extends along the shaft, producing a characteristic “flame” or “blade of grass” appearance (arrows in Figure 74.2D); may involve the entire shaft (Figure 74.2E).

Management ▶ Further diagnostic workup: Plain radiograph and/or CT, if warranted. ▶ Treatment: Bisphosphonates. Further Readings Estrada WN, et al. Paget’s disease in a patient with breast cancer. J Nucl Med. 1993;34:1214–1216. Kim CK, et al. The mouse face appearance of the vertebrae in Paget’s disease. Clin Nucl Med. 1997;22:104–108. Kim CK, et al. Characteristic appearance of facet osteoarthritis of the lower lumbar spine on planar bone scintigraphy with a high negative predictive value for metastasis. Clin Nucl Med. 2008;33:251. Smith SE, et al. Radiologic spectrum of Paget disease of bone and its complications with pathologic correlation. Radiographics. 2002;22:1191–1216.

160

Case 75 History ▶ A 64-year-old man with newly diagnosed prostate carcinoma and elevated PSA level underwent bone scan to evaluate for osseous metastatic disease.

Figure 75.1 

161

Case 75  Paget Disease and Metastatic Prostate Cancer Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Diffusely increased uptake throughout the enlarged left femur with lateral bowing—virtually pathognomonic of Paget disease

▶ Multiple foci of increased uptake randomly distributed in bilateral ribs (some are perpendicular in axis and involve rib segments) in right scapula and pelvic bones—highly suggestive of metastases

▶ Lesions in the skull, sternum, and spine—either metastases or Paget disease. Differential Diagnosis (Left Femur) ▶ Primary bone malignancy (e.g., osteosarcoma, Ewing’s sarcoma) ▶ Fibrous dysplasia.

Teaching Points ▶ Skeletal metastases ■ Up to 90% of patients with skeletal metastases present with multiple lesions. ■ Skeletal metastases usually originate in hematopoietic marrow, followed by cortical involvement; hence, about 80% of lesions are in the axial skeleton.

▶ Bone scan ■ More sensitive than radiography; detects bone metastases up to 18 months before they become radiographically evident.

■ Can be nonspecific due to false positives due to degenerative change, inflammation, Paget disease, and trauma. ■ Distribution (random vs. geographic), pattern, shape, and location of the lesions can help distinguish metastatic from benign process.

■ SPECT/CT imaging further improves accuracy by anatomic localization and assessment of underlying bone pathology (see Case 90).

■ A PSA level > 15–20 ng/mL is generally used as the cutoff point for obtaining a bone scan. Patients who

have skeletal symptoms and those who have a high Gleason score or advanced stage should also be assessed with a bone scan. ▶ Typical patterns of Paget disease should be kept in mind so as not to mistake these for metastatic disease.

Management ▶ Treatment of metastatic prostate cancer. Further Readings Brown ML. Bone scintigraphy in benign and malignant tumors. Radiol Clin North Am. 1993; 31:731–738. Dasgeb B, et al. The current status of bone scintigraphy in malignant diseases. Semin Musculoskeletal Radiol. 2007;11:301–311. Porcaro AB, et al. Prostate cancer and coexisting incidental Paget’s disease—report on a case. Int Urol Nephrol. 2001;33:499–502.

162

Case 76 History ▶ A 64-year-old man with metastatic prostate carcinoma underwent a bone scan before combined

hormone and chemotherapy and a repeat bone scan 3 months after therapy to assess response. There was an interval decrease in PSA level.

Before therapy

3 months after therapy

Figure 76.1 

163

Case 76  Flare Phenomenon

Before therapy

3 months after therapy

Figure 76.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Multiple metastatic lesions with interval increased intensity of tracer uptake and size (e.g., bilateral pelvic lesions) following therapy as well as appearance of possible new lesions (e.g., Figure 76.2; arrow).

Differential Diagnosis ▶ Progression of metastatic disease vs. flare phenomenon. Teaching Points ▶ In patients with apparent response to chemo- or hormonal therapy, a bone scan performed within the

first 3 months of therapy can show “flare phenomenon” characterized by an increased intensity at sites of previously detected metastases or even apparent new sites that actually reflect responsive lesions undergoing repair with increased osteoblastic activity. ▶ Flare phenomenon is commonly associated with cancers of the breast and prostate. ▶ New bone lesions that appear 6 months or later after treatment, or existing bone lesions with interval increase in intensity after 6 months or later, almost always indicate progression. ▶ In most FDG-avid malignancies including breast cancer, FDG PET has proven to be an effective modality for early assessment of therapeutic response by showing rapid reduction in FDG uptake by lesions in responders following chemotherapy. ▶ In breast cancer patients, flare phenomenon has also been described on FDG PET, but only with anti-estrogen therapy. Investigators performed paired FDG PET studies in 40 women with ER-positive breast cancer before and at 7–10 days after the introduction of Tamoxifen therapy. In the responders, the tumor FDG uptake increased after Tamoxifen by 28.4%, while in nonresponders, there was no significant change in tumor FDG uptake from baseline.

Management ▶ This patient was clinically responding to therapy with decreasing tumor markers and remained on the same therapy.

Further Readings Dasgeb B, et al. The current status of bone scintigraphy in malignant diseases. Semin Musculoskeletal Radiol. 2007;11:301–311. Mortimer JE, et al. Metabolic flare: indicator of hormone responsiveness in advanced breast cancer. J Clin Oncol. 2001;19:2797–2803.

164

Case 77 History ▶ A 58-year-old man with history of renal cell carcinoma. Rule out bone metastasis.

Figure 77.1 

165

Case 77  Bone Tracer Uptake in Cerebral Infarct

Figure 77.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Increased tracer uptake within the right side of the head. The appearance seen in this case is typical of infarct in the middle cerebral artery territory.

▶ Non-visualization of right kidney is consistent with history of nephrectomy. ▶ Markedly distended urinary bladder with condom catheter in place (Figure 77.1) ▶ CT: a hypodense area compatible with right middle cerebral artery territory infarct. Differential Diagnosis ▶ Calvarial metastasis ▶ Intracranial malignancy ▶ Inflammatory process (e.g. abscess) Teaching Points ▶ Bone-seeking radiopharmaceuticals, e.g., Tc-99m HDP/MDP, localize in regions of dystrophic calcification

associated with tissue injury such as with infarct, tumor, or trauma, as long as blood flow is present. Areas of infarction are often less Tc-99m HDP/MDP avid after several days, although it can take up to 4 months for the uptake to resolve, with duration of uptake that varies, depending on involved tissue. For example, myocardial uptake may persist only a few days after infarction, whereas tracer uptake associated with cerebral or splenic infarct may persist much longer. ▶ In the brain, tracer accumulation may be seen in any pathologic process that causes breakdown of blood-brain barrier due to extravasation, not only with infarct. ▶ Tc- 99m pyrophosphate has a greater affinity than Tc-99m MDP for infarcted tissue and is the primary agent for myocardical infarct-avid imaging. ▶ If uncertainty exists as to the location of abnormality, i.e., skull metastasis vs. intracranial process, SPECT or SPECT/CT imaging should be obtained.

Management ▶ CVA treatment: Supportive measures and treatment of complications. Further Readings Peller PJ, et al. Extraosseous Tc-99m MDP uptake: a pathophysiologic approach. Radiographics. 1993;13:715–734. Worsley DF, et al. Uptake of technetium-99m MDP in primary amyloidosis with a review of the mechanisms of soft tissue localization of bone seeking radiopharmaceuticals. J Nucl Med. 1993;34:1612–1615.

166

Case 78 History ▶ A 17-year-old man with paraplegia and right hip deformity underwent three-phase bone scan of the pelvis and hips.

Blood Flow

Blood Pool

Delayed Scan

Anterior

Posterior

Figure 78.1 

167

Case 78  Heterotopic Ossification

Figure 78.2 

Figure 78.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Dynamic flow images 60 seconds, immediate static (blood pool) image, delayed imaging 2–3 hours after injection.

Findings ▶ Increased uptake in all three phases of bone scan in the right hip (Figure 78.2). Delayed planar images show increased activity in the region of the greater trochanter, more intense on the posterior view.

▶ SPECT/CT (Figure 78.3) confirms extraosseous uptake, localized to heterotopic bone posterolateral to the

proximal femur. Note the variable degree of activity with decreased uptake in matured heterotopic ossification areas as compared to less matured areas.

Differential Diagnosis ▶ Fracture ▶ Osteomyelitis ▶ Parosteal osteosarcoma (more ossified in the center and less well defined in the periphery) ▶ Osteochondroma (communicates with medullary cavity of bone) ▶ Dermatomyositis (calcifications are more superficial and linear). Teaching Points ▶ Etiologies: trauma, post-prosthesis, immobilization due to paralysis (brain or spinal cord injury), infection, burns, hemophilia, neuromuscular disorders, and drug abuse (with intramuscluar injections).

▶ Flow and blood pool images will be abnormal as early as 2.5 weeks after injury, and delayed images become positive about 1 week later.

▶ Typically, heterotopic ossification is completely separated from the underlying bone by a radiolucent cleft on X-ray, but may occasionally fuse with adjacent bone to mimic an osteochondroma.

▶ Serial bone scans are used to monitor metabolic activity of heterotopic ossification to determine the

appropriate time for surgical resection (interval decrease of initially increased blood flow, blood pool activity, and delayed bone uptake back to the normal level). Surgery is generally delayed until the heterotopic ossification has stabilized.

Management ▶ Further diagnostic workup, such as MRI, if warranted ▶ Physical therapy—controversial ▶ Orthopedic consultation—surgical excision when heterotopic ossification is matured. Further Reading Shehab D, et al. Heterotopic ossification. J Nucl Med. 2002;43:346–353.

168

Case 79 History ▶ A 52-year-old man with bony pain of the legs and arms underwent evaluation with whole body Tc-99m HDP bone scan.

Figure 79.1 

169

Case 79  Hypertrophic Osteoarthropathy A

B

C

Figure 79.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Diffusely increased tracer uptake along the cortical margins of the long bones of lower extremities and distal upper extremities (patient shown in Figures 79.1 and 79.2A)

Differential Diagnosis ▶ Metabolic bone disease ▶ Stress injury, e.g., shin splint. Teaching Points ▶ Hypertrophic osteoarthropathy is a syndrome characterized by excessive proliferation of skin and bone at the distal parts of extremities, digital clubbing, and periostosis of the tubular bones. ■ Initially, excessive connective tissue and subperiosteal edema elevate the periosteum; then, new osteoid matrix is deposited beneath the periosteum. ▶ Hypertrophic osteoarthropathy occurs in up to 10% of patients with bronchogenic carcinoma. ▶ Other etiologies: bronchiectasis, cystic fibrosis, mesothelioma, pneumoconiosis, cyanotic heart disease, and inflammatory bowel disease. ▶ Bone scan: ■ Diffusely increased uptake in the periosteum, often symmetrical and linear, as seen in Figure 79.2A; can be heterogeneous and more limited to the metaphyses/distal diaphyses, as seen in Figures 79.2B and 79.2C (more so in C). ■ Clubbed digits may also show increased radiotracer activity in early flow images, if performed.

Management ▶ If the bone scan finding is incidental, further diagnostic workup, such as chest CT, should be performed to exclude lung cancer.

▶ Management of hypertrophic osteoarthropathy varies depending on the underlying etiology; symptoms generally improve/resolve following treatment of the underlying condition, e.g., tumor resection.

Further Reading McAfee JG. Radionuclide imaging in metabolic and systemic skeletal diseases. Semin Nucl Med. 1987;17:334–349.

170

Case 80 History ▶ A 42-year-old woman with right knee pain.

Figure 80.1 

171

Case 80  Metastatic Calcification/Renal Osteodystrophy

Figure 80.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Tracer uptake in the lungs, stomach (long arrow), dextrocardiac myocardium (arrowhead) and soft tissue adjacent to the right knee, suggestive of metastatic calcification.

▶ Mild uptake in a small right kidney (thick arrow) that is likely part of metastatic calcification rather than physiologic activity, given absence of bladder activity.

▶ Tracer uptake along the appendicular skeleton, skull, and mandible is prominent, which is compatible with metabolic bone disease. The patient has secondary hyperparathyroidism due to end-stage renal disease.

Differential Diagnosis ▶ Dystrophic soft tissue calcification ▶ Metabolic soft tissue uptake/microcalcification ▶ Recent Tc-99m based radiotracer administration such as Tc-99m pertechnetate or Tc-99m sestamibi (but less likely given the overall distribution of radioactivity).

Teaching Points ▶ Metastatic calcification occurs in non-osseous, viable tissue in the presence of primary or secondary

hyperparathyroidism or severe/rapid hypercalcemia due to any disease causing destruction of bones, vitamin D–related disorders including sarcoidosis (macrophages activate a vitamin D precursor), and milk-alkali syndrome. ■ Given the constellation of the scan findings (especially the kidney and bladder), the cause of metastatic calcification in this patient is secondary hyperparathyroidism resulting from end-stage renal disease. ■ In secondary hyperparathyroidism, the serum calcium level is typically low. ▶ The solubility product for calcium and phosphate is exceeded, leading to precipitation of calcium in the extracellular space.

Management ▶ Management of hyperparathyroidism according to the cause as well as calcium/phosphate imbalance. Further Reading Zuckier LS, et al. Nonosseous, nonurologic uptake on bone scintigraphy: atlas and analysis. Semin Nucl Med. 2010;40:242–256.

172

Case 81 History ▶ A 66-year-old man with history of colon carcinoma.

Figure 81.1 

173

Case 81 Dystrophic Calcification—Mucinous Colon Metastatic Cancer

Figure 81.2 

Figure 81.3 

Figure 81.4 

Figure 81.5 

RYadiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings (Figures 81.1 and 81.2) ▶ Large ill-defined soft tissue uptake in the right upper abdomen corresponding to a large hypodense lesion in the right hepatic lobe seen on CT.

Differential Diagnosis (Based on Bone Scan Alone) ▶ Severe hepatitis with tissue necrosis (an example shown in Figure 81.3) ▶ Bleeding ▶ Metastatic calcification (see Case 80), but unlikely given the location and pattern of this uptake. Teaching Points ▶ Soft tissue uptake may be seen in: ■ Tumors that produce osteoid matrix, which binds Tc-99m MDP such as osteogenic sarcoma ■ Tumors that produce mucin (as in this case), which possess a glycoprotein that is biochemically similar to ossifying cartilage and binds Ca2+ salts ■ Neuroblastoma, related to intrinsic metabolic characteristic of this tumor. ▶ Dystrophic calcification occurs in patients with normal Ca2+ levels secondary to histological disruption of tissue by trauma, ischemia, or cellular necrosis such as: ■ Infarctions of brain (Case 77) and heart (Figure 81.4), muscle infarct in uterine myomata, rhadomyolysis, and splenic infarct (Figure 81.5) in sickle cell anemia “auto-infarction” ■ Uptake in IM injection sites, in scars, and in soft-tissue diseases such as dermatomyositis ▶ Compartmental sequestration: ■ Soft tissue tracer accumulation can be caused by rapid delivery of tracer into extracellular compartment in hyperemia or by reduced soft tissue clearance due to lymphatic or venous obstruction. In such cases, a relative localized activity is apparent on delayed images.

Management ▶ Correlation with CT or MRI. If CT or MRI is not available, then continue with SPECT/CT of bone scan. ▶ Appropriate treatment of underlying etiology. Further Reading Zuckier LS, et al. Nonosseous, nonurologic uptake on bone scintigraphy: atlas and analysis. Semin Nucl Med. 2010; 40:242–256.

174

Case 82 History ▶ A 71-year-old man with history of prostate carcinoma.

Figure 82.1 

175

Case 82 Superscan

Figure 82.2 

Figure 82.3 

Figure 82.4 

Figure 82.5 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Markedly increased, mottled bony uptake throughout the axial skeleton and proximal appendicular skeleton corresponding to the red marrow distribution (Figure 82.2)

▶ Significantly decreased soft tissue and renal activity (Figure 82.2), as compared to normal bone scan in this age group (Figure 82.3).

Differential Diagnosis ▶ Metabolic bone disease, unlikely (see explanations in Teaching Points) ▶ Although manipulation of scan’s display (contrast windows) could spuriously enhance bone activity and decrease background activity, kidneys should still be visualized.

Teaching Points ▶ Superscan is characterized by a strikingly high bone-to-soft tissue ratio, with markedly diminished to absent soft

tissue activity and little or no visualization of the kidneys and/or bladder. Such pattern of uptake has been reported in a variety of malignant and nonmalignant conditions in which there is diffusely increased bone turnover. ▶ Superscan due to metastatic disease is most frequently seen in patients with prostate, breast, and lung cancer; however, it can also be seen with advanced skeletal metastases from other malignancies. Superscan due to metastatic disease typically shows heterogeneously increased uptake predominantly involving the axial skeleton and proximal long bones corresponding to active marrow distribution. Even when increased uptake in the axial skeleton is relatively homogeneous, involvement only of proximal appendicular skeleton (corresponding to the active marrow distribution) is an important clue suggesting metastatic superscan (see Figure 82.4). ▶ In superscan associated with metabolic bone disease (such as hyperparathyroidism, renal osteodystrophy, osteomalacia, hyperthyroidism, acromegaly, and mastocytosis): ■ Uptake is more uniform in appearance and extends into the distal appendicular skeleton (Figure 82.5). ■ Intense calvarial uptake that is disproportionate to that in the remainder of the skeleton is another feature of metabolic bone disease (see Case 80).

Management ▶ Further diagnostic imaging is rarely needed in typical malignant superscan. ▶ In case of a metabolic superscan, appropriate laboratory investigation may be ordered to establish the diagnosis, if unknown.

▶ Treatment of underlying etiologic cause. Further Reading Love C, et al. Radionuclide bone imaging: an illustrative review. Radiographics. 2003;23:341–358.

176

Case 83 History ▶ A 23-year-old ballet dancer with pain in the posterior right ankle for 3 months. She underwent a three-phase bone scan of the feet. Blood flow and blood pool images were unremarkable (not shown). Delayed lateral and medial views of feet are shown in Figure 83.1.

Rt

Lt

Lt

Rt

Figure 83.1 

177

Case 83  Os Trigonum Syndrome

Rt

Lt

Lt

Figure 83.2 

Rt

Figure 83.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Planar delayed bone scan images (Figure 83.2): an area of increased tracer uptake can be seen in the region of the posterior ankle joint.

▶ SPECT/CT images (Figure 83.3) confirm the focus of bony uptake and localizes it to the os trigonum. Differential Diagnosis ▶ Based on clinical findings: ■ Flexor hallucis longus tenosynovitis ■ Inflammation of the retrocalcaneal bursa ■ Subluxation of the peroneal tendons ■ Painful accessory soleus muscle ■ Tarsal tunnel syndrome. ▶ Based on clinical and planar bone scan findings: ■ Fracture of posterior process of the talus (Stieda process) ■ Focal posterior tibiotalar or subtalar arthritis ■ Osteonecrosis of the talus (all are less likely given pattern of uptake, SPECT/CT findings, and normal blood flow/pool images)

■ Achilles tendinitis (unlikely given its location, i.e., posterior to talus instead of calcaneus). Teaching Points ▶ An ossification center forms posterior to the talus between 8 and 13 years of age, which normally fuses with the

talus within 1 year. In approximately 7% of the population, it remains separate and is referred to as the os trigonum.

▶ Os trigonum syndrome results from repetitive microtrauma or acute forced plantar flexion of the foot, as in

soccer or football. Repetitive plantar flexion causes impingement of os trigonum between calcaneus and distal tibia, leading to pain and tenderness along posterior ankle that is exacerbated on plantar flexion or dorsi flexion. ▶ Because of its location between the medial and lateral talar tubercles, inflammatory changes may be seen in flexor hallucis longus tendon and avulsion injuries of posterior talofibular and posterior talocalcaneal ligaments.

Management ▶ Further imaging with MR ■ Sagittal inversion recovery sequence usually shows bone marrow edema of os trigonum and may show fluid/edema between the os trigonum and the talus.

▶ Treatment ■ Conservative therapy including immobilization, activity modification, and possible steroid injection is attempted first.

■ If failed, surgical excision is performed, particularly in active, symptomatic athletes in sports that require plantar flexion movement.

Further Reading Karasick D, et al. The os trigonum syndrome: imaging features. AJR. 1996;166:125–129.

178

Case 84 History ▶ A 26-year-old female runner had a three-phase bone scan for the evaluation of pain in the left heel and mid-portion of the left foot for 1 week. No history of trauma, fall, or recent surgery.

Figure 84.1 

Dorsal

Plantar Figure 84.2 

179

Case 84  Plantar Fasciitis and Metatarsal Stress Fracture

Dorsal

Plantar

Figure 84.3 

Figure 84.4  99mTc-MDP

Radiopharmaceutical/Dose/Procedure: or HDP/25 mCi/Dynamic flow images 60 seconds, immediate static (blood pool) image, delayed imaging 2–3 hours after injection.

Findings ▶ Figure 84.3: Flow images and a blood pool image (last frame) show focal hyperemia in the heel (Finding 1) and the base of the first metatarsal (Finding 2) of the left foot.

▶ Figure 84.4: Delayed images show markedly increased focal activity in the inferior aspect of the calcaneus (Finding 1) and in the base of the first metatarsal bone (Finding 2).

Differential Diagnosis ▶ Finding 1: Calcaneal stress fracture; infection; osteoid osteoma ▶ Finding 2: Traumatic arthritis; fracture Teaching Points (Plantar Fasciitis) ▶ Plantar fascia radiates toward the base of the toes from the medial calcaneal tubercle. ▶ Plantar fasciitis is one of the common causes (especially in runners) of heel pain, often stabbing, in the inferior

aspect of the calcaneus. Pain is usually worse in the morning or after sitting and decreases as the patient begins to walk around. ▶ Bone scan ■ Medial/lateral views typically show focally increased uptake at the site of fascia insertion, even before radiologic changes are evident. ■ The pattern of increased blood pool activity and intensity of delayed focal uptake are reported to be useful in predicting pain relief in response to steroid injection. The responders’ bone scans tend to show more focal increased blood pool activity and more intense delayed uptake when compared to non- or short-term responders.

Management of Plantar Fasciitis ▶ Rest; acetaminophen or ibuprofen; heel and foot stretches; shoes with good supports and cushions ▶ Apply ice; night splint ▶ If above treatments do not work: boot cast; orthotics; steroid injection. Further Readings Frater C, et al. Bone scintigraphy predicts outcome of steroid injection for plantar fasciitis. J Nucl Med. 2006;47:1577–1580. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004438/#adam_007021.disease.treatment (US National Library of Medicine Webpage, accessed on September 20, 2014).

180

Case 85 History ▶ A 77-year-old woman with lower back pain, status post recent fall. Plain X-ray showed T12 and L4 compression fractures of undetermined age (not shown).

Anterior

Anterior

Figure 85.1 

Blood Flow

Blood Pool

Posterior

Posterior

Figure 85.2 

181

Case 85  Acute and Chronic Compression Fractures

Blood Flow

Blood Pool

Figure 85.3  Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Dynamic flow images 60 seconds, immediate static (blood pool) image, delayed imaging 2–3 hours after injection.

Findings ▶ A horizontal, linear hyperperfused and hyperemic area, more clearly noted on blood pool than on flow images

(arrows) and intense uptake in T12 vertebra on the delayed images, compatible with acute compression fracture.

▶ No abnormal uptake in L4, compatible with old compression fracture. ▶ Moderate focal uptake in the anterior right third rib, compatible with rib fracture. ▶ Foci of increased activity in the feet, arthritic and/or post-traumatic in etiology. Differential Diagnosis ▶ Osteomyelitis/discitis (often shows increased uptake in two adjacent vertebrae) ▶ Paget diseases (usually expansile in pattern involving transverse and spinous processes, hence Mickey Mouse pattern; see Case 74)

▶ Primary or metastatic osseous disease (unusual). Teaching Points ▶ Accurate localization of compression fractures and determination of fracture age is critical before vertebroplasty or kyphoplasty that can stabilize vertebrae with prompt relief of associated pain.

▶ Although plain X-ray is generally the first imaging study performed, the age of compression fracture(s), if present, cannot be reliably determined in the absence of comparison studies.

▶ Three-phase bone scan is useful in establishing fracture age. ▶ As with other fractures, most elderly patients will have a positive bone scan by 48 hours; however, scan may not become positive for 3–7 days in up to 5%–10% of patients.

▶ Approximately 60% of compression fractures will demonstrate normal uptake by 1 year and 95% by 3 years. Management ▶ Further diagnostic imaging ■ MRI may also be useful in determining the fracture age; shows damage to the surrounding soft tissues; but cannot be performed in some patients, such as with a pacemaker, and findings may be nonspecific.

▶ Treatment ■ Symptomatic treatment ■ Vertebroplasty or kyphoplasty: Cement was injected into T12 with resolution of pain within 24 hours. ■ In multiple fractures, treat systemic etiology such as osteoporosis or multiple myeloma. Further Reading Maynard AS, et al., Value of bone scan imaging in predicting pain relief from percutaneous vertebroplasty in osteoporotic fractures. AJNR. 2000;21:1807–1812.

182

Case 86 History ▶ An 81-year-old woman with history of breast cancer underwent bone scan for evaluation of severe low back and pelvic pain.

Figure 86.1 

183

Case 86  Sacral Insufficiency Fracture/Multiple Rib Fractures A

Figure 86.2 

Figure 86.3 

B

C

D

E

F

Figure 86.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-MDP or HDP/25 mCi/Imaging 2–3 hours after injection.

Findings ▶ Increased uptake in the sacral body and sacral ala (Figure 86.2). ▶ Multiple foci of increased uptake in bilateral ribs in linear array (Figure 86.3). Differential Diagnosis ▶ Bone metastases (unlikely given the pattern) ▶ Sacral osteomyelitis, if decubitus ulcers and leukocytosis present (again unlikely given the overall findings). Teaching Points ▶ Clinical features: ■ Most sacral insufficiency fractures occur in elderly women with variable presentation. There is usually

severe low-back pain exacerbated by movement with radiation to leg or groin. Most do not have neurological defects and some have tenderness over sacral area, but generally findings are not specific. ■ Most common risk factors are osteoporosis, rheumatoid arthritis, prolonged corticosteroid treatment, and pelvic irradiation. ▶ Bone scintigraphy remains the most sensitive technique for detection of sacral insufficiency fracture, particularly after a minimum time lapse of 48–72 hours from onset of symptoms. ■ Typically shows increased uptake resembling the letter “H” or a “butterfly” (also called “Honda sign”), composed of 2 vertical areas of uptake (both sides of the sacral ala) and horizontal uptake (body of sacrum) (Figure 86.4A/B). ■ Variations in pattern include unilateral sacral ala uptake alone, unilateral sacral ala uptake with a horizontal uptake (Figure 86.4C), bilateral sacral ala uptake without horizontal uptake (Figure 86.4D), horizontal linear uptake alone (Figure 86.4E), and multiple foci of uptake (Figure 86.4F). ■ Often accompanies pubic fractures (arrows); these are generally better seen on anterior views)

Management ▶ Further diagnostic imaging ■ MRI is sensitive demonstrating bone marrow edema of sacral fractures. A fracture line may also be

demonstrated. The appearances can be somewhat nonspecific and might be misinterpreted as metastatic disease, especially if there is a history of prior malignancy. ■ CT is accurate, although sometimes the findings can be subtle, particularly in the setting of osteoporosis. ▶ Treatment ■ Bed rest and analgesia, followed by gradual mobilization with walking aids as pain allows. ■ Treatment of osteoporosis, if present. Further Reading Peh WC, et al. Imaging of pelvic insufficiency fractures. Radiographics. 1996;16:335–348.

184

Case 87 History ▶ A 51-year-old active runner complaining of lower leg pain for 2 weeks had a three-phase bone scan. Plain radiograph was normal.

Blood Pool

Delayed Images

Figure 87.1 

185

Case 87  Shin Splint and Stress Fracture

Anterior

Blood Pool

Figure 87.2 

Delayed Images

Posterior

Anterior Anterior Oblique

Figure 87.3 

Rt Med

Posterior Oblique

Lt Lat

Rt Med pinhole

Figure 87.4 

Radiopharmaceutical/Dose/Procedure: See Case 85.

Findings ▶ Figures 87.1 and 87.2: ■ Focal hyperemia on blood pool image and fusiform increased uptake in the medial aspect of distal left tibia on delayed images, consistent with stress fracture (arrowheads)

■ Mild linear delayed increased uptake along the cortex of the anterolateral tibia on both sides with more prominent blood pool activity in the same region (small arrows), suggestive of bilateral shin splint

▶ Figure 87.3: Different patient with stress fracture and shin splints. See Teaching Points.

Differential Diagnosis for Focal Uptake ▶ Osteoid osteoma: correlate with history and radiograph/CT ■ Patient in Figure 87.4 has proven osteoid osteoma. Focal uptake on the parallel hole images alone is

indistinguishable from stress fracture. However, pinhole view shows the double density sign, characteristic of osteoid osteoma.

Teaching Points ▶ Stress fracture ■ Caused by repetitive forces on normal bone. Bone adapts with remodeling. During remodeling, bone

resorption may exceed replacement, which temporarily weakens the cortex, resulting in microfractures if stress is continually applied. ■ Bone scan ◆ More sensitive (> 80% of stress fractures may not be evident on initial radiographs) and often precedes radiographic changes by 1–2 weeks. ◆ May show increased flow (~ 3–4 weeks) and blood pool activity (~ 6–8 weeks). ◆ Shows focal/fusiform areas of increased uptake, often posteromedially (arrowheads in Figures 87.2 and 87.3), which may last ~ 10–12 weeks. ▶ Shin splint (traction periosteitis) ■ Caused by disruption of Sharpey fibers due to abnormal muscle movement ■ Traction periostitis of tibialis anterior and interosseous membrane causes increased uptake along the anterolateral tibial cortex (thin arrows in Figures 87.2 and 87.3). ■ Traction periostitis of tibialis posterior and soleus causes uptake along the posteromedial tibial cortex (thick arrow in Figure 87.3).

Management ▶ Refrain from exercise for at least 6 weeks. ■ Gross fracture may occur if microfractures are not permitted to heal. ■ Shin splints are mainly treated with anti-inflammatory drugs. Further Reading Zwas ST, et al. Interpretation and classification of bone scintigraphic findings in stress fractures. J Nucl Med. 1987;28:452–457.

186

Case 88 History ▶ A 26-year-old woman with diffuse right forearm and hand pain for 6 weeks underwent evaluation with three-phase bone scan of the forearms and hands.

Figure 88.1 

Figure 88.2 

Figure 88.3 

187

Case 88  Complex Regional Pain Syndrome Radiopharmaceutical/Dose/Procedure: See Case 85.

Findings ▶ Flow (Figure 88.1) and blood pool (Figure 88.2) images show diffuse increased activity in the right forearm and hand.

▶ Delayed images (Figure 88.3) show increased periarticular activity in the right hand and wrist. Differential Diagnosis ▶ Active small joints arthritis (unlikely given the diffuse and unilateral nature of involvement). Teaching Points ▶ Complex regional pain syndrome ■ Characterized by severe, diffuse, nondermatosomal pain associated with painful response to nonpainful stimuli, accompanied by autonomic and atrophic changes, usually following tissue injury

■ Pain associated with changes in skin color, temperature, sweating, edema, and reduced range of motion. ■ Caused by axonal release of certain neuropeptides at the affected nerve fiber endings, leading to

vasodilatation, increased vascular permeability, and erythema, which further stimulate more sensory nerve fibers, resulting in an inflammatory response that lowers pain threshold. ■ Type I: ◆ Formerly known as reflex sympathetic dystrophy ◆ No confirmed nerve injury ◆ Three stages: I. hyperemic stage; II. dystrophic or ischemic stage; III. atrophic stage. ■ Type II: ◆ Formerly known as causalgia ◆ Nerve injury confirmed. ▶ Bone scintigraphy ■ More sensitive than plain X-rays ■ Classic findings: increased flow/blood pool activity and increased periarticular uptake in the affected limb on delayed images. ■ The higher the degree of tracer uptake, the higher the likelihood of a positive response to therapy. ■ Sensitivity is increased as the disorder progresses (approximately 25%, 85%, and 100% in stage I, II, and III, respectively). ■ In children and in late stage of complex regional pain syndrome in adults, flow and uptake may be normal or decreased.

Management ▶ First-line drugs: NSAIDs, steroids, tricyclic antidepressants, anticonvulsants. ▶ Sympathetic nerve block is the second line of therapy when medical management fails, although relief is usually only temporary.

▶ Spinal cord stimulation is used with variable success. Further Readings Intenzo CM, et al. The role of nuclear medicine in the evaluation of complex regional pain syndrome type I. Clin Nucl Med. 2005;30: 400–407. http://www.ninds.nih.gov/disorders/reflex_sympathetic_dystrophy/detail_reflex_sympathetic_dystrophy.htm (NIH website, accessed on September 19, 2014).

188

Case 89 History ▶ A 59-year-old man with diabetes and history of left foot ulcer for 6 weeks underwent three-phase bone scan evaluation. Flow

R

Blood Pool

Delayed

L

Figure 89.1 

189

Case 89  Osteomyelitis and Cellulitis Flow

R

Blood Pool

Delayed

L

Figure 89.2 

Figure 89.3 

Figure 89.4 

Figure 89.5 

Radiopharmaceutical/Dose/Procedure ▶ 99mTc-MDP or HDP/25 mCi/Dynamic flow images 60 seconds, immediate static (blood pool) image, delayed imaging 2–3 hours after injection. ▶ 111In-WBC/0.5 mCi/imaging at 24 hours after injection.

Findings ▶ Figure 89.2: Diffuse hyperemia in the left foot; focal increased activity in the left 5th metatarsophalangeal region on both blood pool and delayed images

▶ Figure 89.3 (In-111 WBC scan): similar but slightly larger area of uptake in the same region. ▶ Figure 89.4 (dual isotope SPECT/CT in the same patient): focal uptake (red arrows) in the 5th metatarsal head on both bone and WBC scans; only WBC uptake in the base of left 5th toe (adjacent soft tissue infection/cellulitis).

Differential Diagnosis ▶ Trauma/fracture (difficult to distinguish from infection with three-phase bone scan alone) ▶ Cellulitis, unlikely in this case. Cellulitis typically demonstrates diffuse increased activity on blood flow/pool images, with no focal abnormality on delayed images. Mildly increased uptake in bone adjacent to cellulitis may be seen. Figure 89.5 is an example showing diffusely increased blood flow/pool activity, mild delayed uptake (red arrow), and increased WBC uptake in the soft tissue (yellow arrows).

Teaching Points ▶ Bone scan is highly sensitive and can detect osteomyelitis 1–3 weeks before radiographic changes occur. ■ Findings could be nonspecific in disrupted bones (trauma, orthopedic hardware, etc.) and may remain positive on delayed images for up to 1–2 years following successful treatment.

■ Addition of In-111 or 99mTc-HMPAO WBC scan improves specificity for evaluation of osteomyelitis.

▶ See Cases 12, 16, and 26 for the utility of variable radiotracers for evaluation of vertebral osteomyelitis. ▶ See Case 20 (Osteomyelitis involving a neuropathic joint). ▶ See Case 54 (Osteomyelitis in pediatric patients). Management ▶ Osteomyelitis requires longer antibiotic therapy (4–6 weeks) than soft tissue infection (7–14 days). ▶ Osteomyelitis may require surgical debridement to remove necrotic tissue. Further Reading

Wegener WA, et al. Diagnostic imaging of musculoskeletal infection. Roentgenography; gallium, indium-labeled white blood cell, gammaglobulin, bone scintigraphy; and MRI. Ortho Clin N Am. 1991;22:401–417.

190

Case 90 History ▶ A 57-year-old woman with breast carcinoma.

Figure 90.1 

191

Case 90  Added Value of SPECT/CT in Metastatic Survey Bone Scan

Figure 90.2 

Figure 90.3 

Radiopharmaceutical/Dose/Procedure: after injection.

99mTc-MDP

Figure 90.4  or HDP/25 mCi/Planar and SPECT/CT Imaging 2–3 hours

Findings ▶ Figure 90.1 (Planar images): Although the pattern of increased uptake in T10–12, L4, and left 11th rib is suggestive of post-traumatic or arthritic changes, metastasis cannot be excluded.

▶ Figure 90.2 (SPECT/CT): Uptake in L4 spinous process associated with cortical deformity on CT; foci of

uptake in multiple ribs are associated with fracture line (red arrow) or cortical thickening/callus (yellow arrow) on CT, all compatible with healing fractures; uptake in collapsed T11/12 and facet joints of T9/T10 consistent with compression fractures/arthritic changes, respectively. ▶ Figures 90.3 and 90.4: Companion cases of confirmed metastatic disease. Note the location of increased uptake on SPECT or SPECT/CT.

Differential Diagnosis ▶ Osseous metastases ▶ Trauma/fracture ▶ Degenerative, arthritic, and postsurgical changes. Teaching Points ▶ Whole-body planar bone scintigraphy is the study of choice for evaluation in many cancer patients. ■ More sensitive than radiographs and permits whole skeletal survey. ■ Specificity may be limited by other processes such as post-traumatic/arthritic changes. ■ Uptake pattern, location/distribution, history, and SPECT/CT help to differentiate, as illustrated in two cases.

▶ SPECT improves sensitivity: Detects 20%–50% more lesions when compared to planar images. ▶ SPECTCT further enhances specificity: Improves anatomic localization and permits evaluation for underlying bone pathology.

▶ Pattern of metastatic lesions ■ 80%–90% are multiple and in axial skeleton. ■ Rib lesions are parallel/oblong rather than focal and are randomly distributed. ■ Vertebral lesions are within bones, particularly body and pedicles (vs. exophytic/osteophytic and facet jointcentered uptake in degenerative/arthritic disease).

Management ▶ Further imaging, such as plain radiograph or CT, is rarely needed in typical osseous metastases or when SPECT/CT is used.

▶ Additional characterization with MR or histopathology may be performed for solitary or atypical lesions. Further Reading E. Even-Sapir. Imaging of malignant bone involvement by morphologic, scintigraphic, and hybrid modalities. J Nucl Med. 2005;46:1356–1367.

192

Part 7

PET/CT in Oncology I Heather A. Jacene, Chun K. Kim, Christopher G. Sakellis, Katherine A. Zukotynski

Case 91 History ▶ None. Figure 91.1 shows a maximum intensity projection (MIP) image (left) and selected coronal

and sagittal FDG-PET (top) and PET/CT co-registered (bottom) images. Figure 91.2 shows selected axial FDG-PET (top) and PET/CT co-registered (bottom) images.

Figure 91.1 

Posterior

Posterior

Posterior

Figure 91.2 

195

Case 91  18F-FDG-PET/CT Procedure and Physiologic Distribution

Figure 91.3  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi for 3D acquisition (10–20 mCi for 2D acquisition)/PET-CT imaging 1 hour after injection (see Teaching Points for more details). Findings: Essentially physiologic distribution of FDG (except for an FDG-avid left lung nodule)

Teaching Points ▶ Preparation prior to FDG administration: ■ Patients should fast 4–6 hours (4 hours for diabetic patients, 6 hours for nondiabetic patients). Water is allowed during the fasting period.

■ Blood glucose should be checked; < 150 mg/dL preferred (< 200 mg/dL in diabetic patients).

▶ During FDG uptake period: ■ Patients should rest in a dimly lit, warm room without speaking or moving. ■ Ask patient to void prior to the scan. ▶ Image acquisition: ■ One hour after FDG administration, CT is performed, followed by PET (2D or 3D). ■ The field of view for most oncologic indications is from the skull base to mid-thigh. The rest of the brain and/or legs are included as indicated.

▶ Typical physiologic FDG uptake in various organs/tissues: ■ Brain: gray matter (high), white matter (low) ■ Head/Neck: salivary glands, lymphoid tissues and ocular/vocal muscles: low to moderate ■ Lungs: minimal ■ Mediastinum: low ■ Myocardium: variable (minimal to intense) depending on the concentration of fatty acids, glucose, and insulin in blood

■ Nipple/areola: low ■ Liver: low to moderate ■ Spleen: low ■ GI tract: esophagus (minimal), stomach (low to moderate; arrows in Figure 91.3), small intestine (low), colon (low to moderate; rectosigmoid and cecum are generally highest)

■ Urinary tract: Due to FDG excretion in urine, renal pelvis/collecting system and bladder are almost invariably intense. Ureters are also often seen.

■ Testis: low to moderate ■ Ovary, uterus, fallopian tubes: variable depending on the menstrual cycle ■ Bone marrow: low ■ Muscles: low at rest, moderate after exercise or in hyperinsulinemic state. Further Reading Cook GJ, et al. Normal physiological and benign pathological variants of 18-fluoro-2-deoxyglucose positron-emission tomography scanning: potential for error in interpretation. Semin Nucl Med. 1996;26:308–314.

196

Case 92 History ▶ A 28-year-old woman with history of lymphoma, in remission.

Figure 92.1 

197

Case 92 Altered 18F-FDG Biodistribution With Diffuse Increased Uptake in Skeletal Muscle Due to Eating Right Before Scan

Figure 92.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Diffusely increased FDG uptake in skeletal muscle, namely the musculature around the shoulders and hips, abdominal musculature, and intercostal muscles.

▶ Distension of the stomach with ingested material (the patient ate lunch shortly before imaging). Differential Diagnosis ▶ Hyperinsulinemia ▶ Hyperglycemia from steroids or intravenous fluids containing dextrose ▶ Intense physical activity. Teaching Points ▶ Increased FDG uptake in skeletal muscle is associated with an elevated insulin level at the time of FDG administration.

▶ Patients who eat, take intravenous insulin, or who are in a hyperglycemic state from steroid injections shortly before FDG administration will have elevated insulin levels, and increased FDG in skeletal muscle cells.

▶ Intense physical exertion prior to a PET/CT scan can cause increased skeletal muscle FDG uptake due to

increased glycolysis from muscular contraction. Type of exercise and distribution of FDG uptake should be correlated.

Management ▶ To prevent increased skeletal muscle FDG uptake, nondiabetic patients are instructed to fast for 6 hours

before their PET/CT scan, while insulin-dependent diabetics are instructed to avoid insulin for 4 hours before their scan. ▶ Patients are also asked to avoid intense physical exertion for the 2 days leading up to the exam. Further Reading Delbeke D, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0. J Nucl Med. 2006;47:885–895.

198

Case 93 History ▶ A 68-year old man with history of malignancy complaining of generalized weakness and body pain underwent FDG-PET/CT for restaging.

Figure 93.1 

199

Case 93  Polymyositis (Statin-Associated)

Figure 93.2 

Figure 93.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection

Findings ▶ Figure 93.2: Diffuse muscle uptake throughout the body with no appreciable myocardial uptake or blood pool activity in the heart region.

Differential Diagnosis ▶ Polymyositis; Rhabdomyolysis; Hyperinsulinemia; Excessive exercise; Hyperglycemia. Teaching Points ▶ Figure 93.2 shows polymyositis, a rare potentially debilitating complication of lipid-lowering drugs. ▶ The presence of polymyositis can limit the sensitivity of FDG-PET/CT to detect malignancy. ▶ Scan interpretation (Figure 93.2): ■ Rhabdomyolysis rarely shows the homogeneous and symmetrical muscle uptake, as is the case in Figure 93.2 and would be considered unlikely (see Further Readings).

■ Hyperinsulinemia is effectively excluded from the differential given the absence of myocardial uptake. A case

of hyperinsulinemia is shown in Case 92 with intense myocardial uptake in addition to diffuse muscle uptake.

■ Excessive exercise would also be unlikely given the involvement of virtually the entire musculature in the body, including the deep muscles such as psoas.

■ Hyperglycemia tends to cause diffuse soft tissue activity (not predominantly muscle uptake), as shown in Figure

93.3. The blood glucose was 279 mg/dL at the time of the PET/CT. Diffusely decreased brain uptake (SUV 2.5–3 in this case) is an important clue suggesting altered biodistribution, even when more obvious evidence such as diffusely increased muscle uptake throughout the body, as in Figure 93.2 and Case 92, is not present. ■ Tumor uptake, as given by the standardized uptake value (SUV), in all of the above conditions is generally underestimated.

Management ▶ Muscle biopsy revealed polymyositis. ▶ Statin was discontinued. Further Readings Pipitone N, et al. 18F-Fluorodeoxyglucose positron emission tomography for the assessment of myositis: a case series. Clin Exp Rheumatol. 2012;30:570–573. Sheehy N, Israel DA. Findings on (18)FDG-PET imaging in statin-induced rhabdomyolysis. Clin Radiol. 2007;62:1012–1014.

200

Case 94 History ▶ A 42-year-old man with melanoma. Initial Staging

6 months later

Figure 94.1 

201

Case 94 Melanoma Axial T1 post-gadolinium

Axial T2 Flair

6 months later

Figure 94.2 

Figure 94.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings (Figure 94.2) ▶ Photopenic defect in the right parietal lobe correlating to a hypodense lesion on CT ▶ Normal FDG uptake in the rest of the brain. Differential Diagnosis ▶ Edema with underlying brain metastasis ▶ Cerebrovascular accident. Teaching Points ▶ Brain metastases are more common than primary brain tumors. ▶ Most common primary tumors to metastasize to the brain: lung, breast cancer, and melanoma. ▶ PET is less sensitive for detecting brain metastases compared to contrast-enhanced magnetic resonance

imaging (MRI) due to high FDG uptake in normal gray matter and typical occurrence of metastases at the gray-white junction. ▶ On PET, brain metastases may be hypermetabolic, isometabolic, or hypometabolic, compared to normal gray matter. ▶ Hypometabolic or photopenic defects in the brain may be due to: ■ Brain metastases: decreased blood flow to the tumor caused by surrounding edema and small lesions below the resolution for detection by PET. ■ Cerebrovascular accidents: decreased blood flow and infarcted tissue, typically in a vascular pattern. ■ Correlation with MRI is essential.

Management ▶ Follow-up with brain MRI, which demonstrated an underlying brain metastasis and edema (Figure 94.3). Further Readings Griffeth LK, et al. MCGuire AH, Siegel BA. Brain metastases from non-central nervous system tumors: evaluation with PET. Radiology. 1993;186:37–44. Rohren EM, et al. Screening for cerebral metastases with FDG PET in patients undergoing whole-body staging of non-central nervous system malignancy. Radiology. 2003;226:181–187.

202

Case 95 History ▶ A 50-year-old woman with recently diagnosed nasopharyngeal cancer for staging FDG-PET/CT.

Axial fused PET/CT, CT, and FDG-PET images at the level of the nasopharynx, and a MIP image are shown in Figure 95.1. What stage is the malignancy?

Figure 95.1 

203

Case 95  Nasopharyngeal Cancer (NPC)

Figure 95.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Axial PET/CT images: FDG-avid right nasopharyngeal soft tissue, an FDG-avid node of Rouviere (retropharyngeal node)

▶ MIP image: FDG-avid right neck lymph nodes (level 2 and 3). Differential Diagnosis ▶ The FDG-avid lymph nodes could be metastatic, inflammatory, or infectious, but are highly suspicious for malignancy in this case given the intensity, location, and known primary nasopharyngeal cancer.

Teaching Points ▶ NPC is an epithelial malignancy that may be associated with genetic mutations, chronic inflammation, and viral infections, especially the Epstein-Barr virus (EBV).

▶ FDG-PET/CT is helpful to localize the primary malignancy, and stage the disease. ▶ Tumor confined to the nasopharynx, nasal cavity, and oropharynx is potentially treatable with radiotherapy.

Side effects of therapy can be lifelong, and an accurate delineation of the tumor is essential to guide appropriate therapy for optimal outcome. FDG-PET/CT findings can change disease stage, patient prognosis, and management. ▶ To separate FDG-avid primary nasopharyngeal malignancy from adjacent FDG-avid adenopathy, the emission image intensity should be adjusted.

Management ▶ The above patient had nasopharyngeal cancer spread to ipsilateral nodes and was treated with chemoradiotherapy.

Further Readings Edge S, et al. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010:41–56 Branstetter BF 4th, et al. Head and neck malignancy: is PET/CT more accurate than PET or CT alone? Radiology. 2005;235(2):580–586. Ng SH, et al. Staging of untreated nasopharyngeal carcinoma with PET/CT: comparison with conventional imaging work-up. Eur J Nucl Med Mol Imaging. 2009;36(1):12–22.

204

Case 96 History ▶ A 42-year-old man with lung cancer.

Figure 96.1 

205

Case 96  Recurrent Lung Cancer

Figure 96.2 

Figure 96.3 

Figure 96.4 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings (Figure 96.2) ▶ Asymmetric FDG uptake in the right vocal cord and cricoarytenoid muscle ▶ Medial lateralization of the left vocal cord (arrow). Differential Diagnosis ▶ Paralyzed left vocal cord, physiologic FDG uptake in the right vocal cord ▶ Primary right vocal cord malignancy. Teaching Points ▶ Asymmetrically decreased uptake in a vocal cord associated with medial lateralization on CT is a typical pattern for a paralyzed vocal cord. Uptake in the contralateral vocal cord is physiologic.

▶ This can be seen in patients with head and neck malignancies postoperatively due to direct injury to the

laryngeal nerve or due to laryngeal nerve compression in patients with tumors at the lung apex or surrounding the aortic arch where the recurrent laryngeal nerve passes (Figure 96.3). ▶ Physiologic uptake in the vocal cords and cricoarytenoid muscles is related to “work” from speaking. ▶ Patients should refrain from speaking during the uptake phase portion of the PET/CT scan, especially if undergoing evaluation for head and neck cancer. ▶ Figure 96.4: Asymmetric increased FDG uptake in the paralyzed vocal cord itself may raise a question of metastasis or a primary malignancy. Injection of a synthetic material into the paralyzed vocal cord muscle, which is often performed to improve the quality of speech, induces a granulomatous reaction, hence the intense FDG uptake. Misinterpretation may be avoided by correlating with CT, which will show hyperdensity corresponding to the synthetic material.

Management ▶ Correlation with findings on head and neck examination. Further Readings Halpern BS, et al. Intense focal F-18 uptake in vocal cord associated with injection of calcium hydroxylapatite microspheres. Clin Nuc Med. 2011;36:e175–177. Kamel EM, et al. Recurrent laryngeal nerve palsy in patients with lung cancer: detection with PET-CT image fusion—report of 6 cases. Radiology. 2002;224:153–156. Kostakoglu L, et al. Speech-related visualization of the laryngeal muscles with Fluorine-18-FDG. J Nucl Med. 1996;37:1711–1713.

206

Case 97 History ▶ A 36-year-old man with lymphoma post-chemotherapy, for restaging on FDG-PET/CT. According

to the medical records, there was an intensely FDG-avid right thyroid gland nodule on the baseline study and lymphadenopathy above and below the diaphragm.

Figure 97.1  Axial fused PET/CT, CT and FDG-PET at the level of the neck.

Figure 97.2  MIP image.

207

Case 97  Incidental Thyroid Nodule

Figure 97.3  Axial fused PET/CT and CT at the level of the neck

Figure 97.4  MIP image

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings (Figures 97.3 and 97.4) ▶ Intensely FDG-avid right thyroid gland nodule ▶ Moderately FDG-avid intramuscular nodule in the proximal right thigh (dotted arrow in Figure 97.4). Differential Diagnosis ▶ Intensely FDG-avid thyroid gland nodule: ■ Primary thyroid neoplasm: thyroid cancer or adenoma ■ Lymphoma ▶ Moderately FDG-avid intramuscular soft tissue nodule: ■ Trauma ■ Lymphoma. Teaching Points ▶ Approximately 10%–50% of FDG-avid thyroid nodules represent a thyroid malignancy. ▶ In general, more aggressive/malignant disease demonstrates more intense FDG uptake; however, there is

no reliable “cutoff ” value of intensity to differentiate benign from malignant disease. Therefore, thyroid ultrasound and fine needle aspiration are needed in the presence of focal thyroid uptake detected by FDG-PET/CT. Focal intramuscular FDG uptake can be due to inflammation from trauma, malignancy, or rarely, localized infection.

Management ▶ The intensely FDG-avid thyroid nodule was reportedly present on the pre-therapy study, and given the

absence of residual FDG uptake in nodes elsewhere, the lack of change in intense FDG uptake in this thyroid gland nodule suggests a different metabolic process. Differential consideration includes primary thyroid malignancy or adenoma. Biopsy is needed for a definitive diagnosis. ▶ The moderately FDG-avid intramuscular nodule in the proximal right medial thigh is indeterminate for residual malignancy given that the appearance of this lesion at baseline is unknown. Clinical correlation and comparison with prior imaging are needed. Further Readings Ho TY, et al. Prevalence and significance of thyroid uptake detected by (18)F-FDG PET. Endocrine. 2011;40(2):297–302. Kim BH, et al. Risk stratification and prediction of cancer of focal thyroid fluorodeoxyglucose uptake during cancer evaluation. Ann Nucl Med. 2010;24(10):721–728. Shie P, et al. Systematic review: prevalence of malignant incidental thyroid nodules identified on fluorine-18 fluorodeoxyglucose positron emission tomography. Nucl Med Commun. 2009;30(9):742–748. Yun M, et al. Visually discernible 18F-FDG uptake in papillary thyroid microcarcinoma: a potential new risk factor. J Clin Endocrinol Metab. 2010;95:3182–3188.

208

Case 98 History ▶ A 58-year-old woman with new diagnosis of lung cancer.

Axial fused PET/CT, CT and FDG-PET at the level of the lower neck.

Figure 98.1 

MIP image.

Figure 98.2 

209

Case 98  Hashmoto Thyroiditis (Incidentally Noted)

Figure 98.3 

Figure 98.4 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection

Findings ▶ Figure 98.4: Widepread metastatic lung cancer (Stage IV) ▶ Figures 98.3 and 98.4: Incidentally detected diffuse FDG uptake throughout the thyroid gland. Differential Diagnosis ▶ Drug-induced thyroiditis ▶ Graves disease ▶ Normal variant. Teaching Points ▶ Diffuse FDG uptake in the thyroid gland is frequently associated with Hashimoto’s thyroiditis and hypothyroidism, but may be seen with Graves disease.

▶ Mild diffuse thyroid uptake may be a normal variant.

Management ▶ Clinical correlation and correlation with thyroid function tests are needed. Further Readings Chen W, et al. Evaluation of thyroid FDG uptake incidentally identified on FDG-PET/CT imaging. Nucl Med Commun. 2009;30:240–244. Ho TY, et al. Prevalence and significance of thyroid uptake detected by (18)F-FDG PET. Endocrine. 2011;40(2):297–302. Kurata S, et al. Diffuse and diffuse-plus-focal uptake in the thyroid gland identified by using FDG-PET: prevalence of thyroid cancer and Hashimoto’s thyroiditis. Ann Nucl Med. 2007;21:325–330.

210

Case 99 History ▶ A 26-year-old man with Hodgkin lymphoma, post-chemotherapy, for subsequent treatment strategy. What can be done to increase the accuracy of the exam?

Figure 99.1  Axial fused PET/CT, CT and FDG-PET images at the level of the lower neck, and a MIP image.

211

Case 99  Metabolically Active Brown Adipose Tissue

Figure 99.2  Axial fused PET/CT, CT and FDG-PET images at the level of the lower neck, and a MIP image. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10-15 mCi/PET-CT 1 hour after injection.

Findings ▶ FDG uptake in metabolically active brown adipose tissue (BAT) in the cervical, supraclavicular, axillary, and paravertebral regions (thin arrows) limits study sensitivity for FDG-avid pathology.

▶ FDG-avid mediastinal and hilar lymph nodes, consistent with lymphoma (thickarrows). Differential Diagnosis ▶ FDG-avid lymph nodes can be due to infection such as infectious mononucleosis, malignancy such as lymphoma, or inflammatory conditions such as sarcoidosis.

Teaching Points ▶ Metabolically active BAT is the primary site for non-shivering thermogenesis. ▶ FDG uptake is thought to be driven by sympathetic release of norepinephrine. ■ Most common in children, young, thin patients, and women. ■ FDG uptake localizing to fat on CT is pathognomonic for metabolically active BAT. ■ Metabolically active BAT can be reduced by patient warming, diet, or medication.

◆ The most common methods of patient warming are using warm blankets or maintaining the patient injection room temperature at a constant 24oC (75oF). ◆ A high-fat, low-carbohydrate diet is linked with decreased incidence of FDG-avid BAT. ◆ Administration of propranolol, fentanyl, or benzodiazepine prior to the FDG-PET/CT also can reduce FDG uptake in BAT.

Management ▶ In patients with extensive FDG uptake in BAT: ■ FDG-PET/CT must be carefully read not to miss FDG-avid disease. Mitigating maneuvers described earlier should be considered prior to follow-up PET/CT studies.

Further Readings Kim S, et al. Temporal relation between temperature change and FDG uptake in brown adipose tissue. Eur J Nucl Med Mol Imaging. 2008;35:984–989. Kim SH, et al. Concomitant paravertebral FDG uptake helps differentiate supraclavicular and suprarenal brown fat uptake from malignant uptake when CT coregistration is not available. Clin Nucl Med. 2006;31:127–130. Williams et al. Methods for decreasing uptake of 18F-FDG by hypermetabolic brown adipose tissue on PET. AJR. 2008;190:1406–1409. Zukotynski et al. Seasonal variation in the effect of constant ambient temperature of 24 degrees C in reducing FDG uptake by brown adipose tissue. Eur J Nucl Med Mol Imaging. 2010;37:1854–1860.

212

Case 100 History ▶ A 66-year-old man with a known history of pulmonary fibrosis had an FDG-PET/CT to further evaluate a right upper lobe nodule that was increasing in size on CT.

Figure 100.1 

213

Case 100  Lung Cancer (FDG-Avid Solitary Pulmonary Nodule)

Figure 100.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ A 1-cm intensely FDG-avid spiculated nodule and mildly FDG-avid interstitial fibrosis. Differential Diagnosis ▶ Metastasis ▶ Infectious or inflammatory nodule. Teaching Points ▶ There is no intensity of FDG uptake or SUVmax definitive for the diagnosis of malignancy. An intensely

FDG-avid pulmonary nodule suggests aggressive disease and may be due to lung cancer, metastasis, or lymphoma. However, it may also be due to inflammatory or infectious diseases such as sarcoidosis, tuberculosis, or fungal infection. A mildly FDG-avid nodule suggests a non-aggressive process but can be seen with malignancy such as carcinoid or bronchioloalveolar carcinoma. ▶ Certain CT characteristics of pulmonary nodules are considered suspicious for malignancy such as large size, spiculated margins, punctate, stippled or eccentric calcification, and cavitation with a thickened irregular surrounding wall. CT characteristics considered more likely benign include smooth margins or calcification central or throughout the pulmonary nodule. ▶ FDG-PET/CT has been shown to be accurate for the detection of lymph node metastases or contralateral disease, which can help to stage disease.

Management ▶ In the case above, the pulmonary nodule is intensely FDG-avid and has a spiculated margin, suspicious for

malignancy. Given the absence of known primary malignancy, a primary lung cancer was considered more likely than metastatic disease. ■ Wedge resection revealed a poorly differentiated adenocarcinoma.

Further Readings Delbeke D, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0*. J Nucl Med. 2006;47(5):885–895. Webb WR, et al. Fundamentals of Body CT. 3rd ed. Philadelphia: Saunders Elsevier; 2006.

214

Case 101 History ▶ None.

Figure 101.1 

Figure 101.2 

215

Case 101  Adenocarcinoma in Situ

Figure 101.3 

Figure 101.4 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ 1.3 × 1.3 cm, ill-defined ground-glass nodule in the left upper lobe of the lung with mild FDG uptake (Figure 101.3: PET/CT; Figure 101.4: chest CT)

▶ No other abnormal findings were visualized on the FDG-PET/CT scan. Differential Diagnosis ▶ Adenocarcinoma in situ (formerly known as bronchioloalveolar carcinoma) of the lung ▶ Inflammatory or infectious lung nodule. Teaching Points ▶ Bronchioloalveolar carcinoma (BAC) is a well-differentiated lung neoplasm characterized by its growth along intact alveolar septa, without stromal invasion.

▶ BAC may present as a solitary nodule, segmental or lobar consolidation, or multiple nodules. The solitary nodular form often has a characteristic ground-glass appearance on CT.

▶ On PET/CT, pure BAC typically has lower FDG uptake than other subtypes of lung cancer, likely due to the

slow-growing nature of the tumor or low number of active malignant cells. This low level of uptake can be difficult to differentiate from inflammatory and infectious lung processes. Solitary ground-glass nodules, regardless of low FDG uptake, need to be followed for stability or growth. Enlarging lesions, despite continued low-level FDG uptake, should be considered suspicious for a slow-growing malignancy and biopsy should be considered. ▶ Higher levels of FDG uptake are seen in pure BAC with adenocarcinoma.

Management ▶ Surgical resection versus surveillance. Further Reading Gourdarzi B, et al. Diagnosis and differentiation of bronchioloalveolar carcinoma from adenocarcinoma with bronchioloalveolar components with metabolic and anatomic characteristics using PET/CT. J Nucl Med. 2008;49:1585–1592.

216

Case 102 History ▶ A 57-year-old woman with biopsy proven non-small cell lung cancer. PET/CT performed for staging demonstrated known cancer (top row) and an additional mildly FDG-avid nodule in the right upper lobe (bottom row). There were no other sites of FDG-avid disease.

Figure 102.1  Axial fused PET/CT, CT, and FDG-PET at the level of the mid (top row) and upper (lower row) lungs.

217

Case 102 Pulmonary Hamartoma (FDG-Avid Pulmonary Nodule [False Positive])

Figure 102.2  Axial fused PET/CT, CT, and FDG-PET at the level of the mid (top row) and upper (lower row) lungs. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intensely FDG-avid nodule (top row): known NSCLC ▶ Mildly FDG-avid right upper lobe nodule (bottom row). Differential Diagnosis (for the Second Lesion) ▶ Metastatic NCSLC, a second primary pulmonary malignancy, a benign pulmonary nodule. Teaching Points ▶ FDG-PET is useful for initial lung cancer staging, treatment planning, and restaging post therapy. FDG-PET/

CT can distinguish metabolically active malignancy from adjacent atelectasis, provide information on the volume of aggressive disease, and detect disease spread to lymph nodes or distant sites with a higher sensitivity and specificity than CT alone. However, since inflammation or infection can be metabolically active, tissue sampling may be needed for therapy planning. ▶ There is no intensity of FDG uptake that is definitive for the diagnosis of malignancy. An intensely FDG-avid pulmonary nodule may be due to lung cancer, metastatic disease, inflammatory lesions, or infection. A mildly FDG-avid nodule is often seen with benign disease but can also be seen in malignant disease such as carcinoid tumor or bronchioloalveolar carcinoma. ▶ A pulmonary hamartoma is a benign lesion that typically has a smooth or rounded contour and can contain macroscopic (visible) fat and/or “popcorn” appearing calcification.

Management ▶ In the case above, the subcentimeter pulmonary nodule in the right upper lobe was mildly FDG-avid and malignancy could not be excluded. Biopsy revealed a pulmonary hamartoma.

Further Reading Webb WR, et al. Fundamentals of Body CT. 3rd ed. Philadelphia: Saunders Elsevier; 2006.

218

Case 103 History ▶ A 64-year-old man with newly diagnosed adenocarcinoma of the left upper lobe of the lung.

Figure 103.1 

219

Case 103  Lung Cancer Initial Staging (TNM Staging System)

Figure 103.2  Radiopharmaceutical/Dose/Procedure:

Figure 103.3  18F-FDG/10–15

mCi/PET-CT 1 hour after injection.

Findings ▶ 8-cm left upper lobe lung mass with a rim of intense FDG uptake and central photopenia (top row) (Figure 103.2) ▶ Intensely FDG-avid subcarinal lymph node ▶ Focal FDG uptake in the left lateral prostate gland (bottom row). Differential Diagnosis ▶ Left upper lobe lung cancer with central necrosis ▶ Subcarinal lymph node metastasis ▶ Focal FDG uptake in the prostate gland: prostate carcinoma, focal prostatitis, benign prostatic hypertrophy, prostate intraepithelial neoplasm, metastatic lung cancer.

Teaching Points ▶ Staging is based on the 2010 American Joint Committee on Cancer TNM Staging System. ▶ FDG-PET/CT has superior accuracy compared to CT (unenhanced or contrast-enhanced) for mediastinal

nodal staging. In a meta-analysis, the pooled estimates of sensitivity and specificity for identifying mediastinal metastases were 74% and 85% for PET and 51% and 85% for CT. ▶ Initial staging of lung cancer with FDG-PET/CT alters management for a significant number of patients compared to CT alone, including avoidance of futile thoracotomy for ~20% of patients. ▶ Differences in relative FDG uptake in the morphologic abnormality is useful to distinguish areas of necrosis within the tumor (Figure 103.2) and post-obstructive atelectasis (Figure 103.3; arrow), which are typically photopenic or less FDG-avid, from viable tumor in order to guide biopsy. ▶ FDG-PET/CT is not generally indicated for the diagnosis and staging of prostate cancer due to relatively low uptake of FDG in this tumor type. Incidental focal uptake in the prostate gland may represent a primary malignancy, but false positives can occur. Further evaluation is needed, usually correlation with PSA, physical exam, and/or biopsy.

Management ▶ Surgery and adjuvant chemotherapy for stage IIIA lung cancer ▶ Correlation with PSA level, physical exam, and biopsy for the incidental focal uptake in the prostate gland. Further Readings Lardinois D, et al. Staging of non-small cell lung cancer with integrated positron-emission tomography and computed tomography. New Engl J Med. 2003;348:2500–2507. Silvestri GA, et al. Noninvasive staging of non-small cell lung cancer: ACCP evidence-based clinical practice guidelines (2nd Edition). Chest. 2007;132(3 Suppl):178S–201S.

220

Case 104 History ▶ A 58-year-old man with newly diagnosed adenocarcinoma of the right lower lobe of the lung.

Figure 104.1 

221

Case 104  Lung Cancer Initial Staging (Distant Metastases)

Figure 104.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intense FDG uptake in a right lower lobe lung nodule (middle row) ▶ No abnormal FDG uptake in hilar or mediastinal lymph nodes ▶ Intense FDG uptake in bilateral adrenal nodules (bottom row) ▶ Focus of moderately increased FDG uptake in the left thyroid gland (top row). Differential Diagnosis ▶ Right lower lobe lung cancer with adrenal metastases ▶ Right lower lobe lung cancer with adrenal hyperplasia ▶ Focal FDG uptake in the thyroid gland: thyroid carcinoma, thyroid adenoma, metastatic disease from lung cancer. Teaching Points ▶ Staging is based on the 2010 American Joint Committee on Cancer TNM Staging System (see AJCC Cancer Staging Manual, 7th ed., Springer, 2010).

▶ The adrenal gland is a common site for lung cancer metastases. Benign adrenal lesions typically have FDG uptake less than or equal to normal liver parenchyma.

▶ FDG-PET/CT detects occult extrathoracic metastases in 1%–8% of patients with stage I lung cancer and 7%–18% with stage II lung cancer and upstages to stage IV.

▶ In patients with no prior history of thyroid disease, an incidental focus of FDG uptake in the thyroid gland has a high probability (30%–50%) of representing a primary thyroid malignancy. Further evaluation is required, usually ultrasound-guided biopsy. Diffuse FDG uptake throughout the thyroid gland, in contrast to a solitary focus of uptake, is seen in up to 3% of patients undergoing FDG-PET/CT and can be associated with chronic thyroiditis (see Case 98).

Management ▶ Chemotherapy for stage IV lung cancer ▶ Ultrasound confirmation of left thyroid nodule and biopsy. Further Readings See Case 103. Edge SB, et al. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010:262.

222

Case 105 History ▶ A 67-year-old man with recurrent lung cancer presents for FDG-PET/CT 4 months after conformal radiation therapy.

Baseline

After Radiation Therapy

Figure 105.1  Baseline

After Radiation

Figure 105.2 

223

Case 105  Radiation Pneumonitis A

Baseline

B

After Radiation

After Radiation

Figure 105.3  Radiopharmaceutical/Dose/Procedure:

Figure 105.4  18F-FDG/10–15

mCi/PET-CT 1 hour after injection.

Findings ▶ Baseline scan: Intense FDG uptake in a subcarinal mass (Figure 105.3A) ▶ After radiation therapy (RT): Residual moderately increased FDG uptake in the subcarinal mass; new FDG

uptake in right paramediastinal ground-glass opacities in the right upper and middle lobes (Figure 105.3B); relatively decreased FDG uptake in the bone marrow of the mid-thoracic spine (Figure 105.4).

Differential Diagnosis ▶ Baseline scan: Recurrent non-small cell lung cancer ▶ After RT: ■ Highly concerning for residual malignancy in subcarinal mass ■ Lung findings: radiation pneumonitis, infection, or lymphangitic tumor spread. Teaching Points ▶ Most likely diagnosis: Residual malignancy with radiation pneumonitis due to timing after radiation, new opacities, and abnormality within the radiation port

▶ Radiation-induced lung injury has two phases: early pneumonitis followed by chronic fibrosis. ▶ Early radiation pneumonitis typically occurs 1–6 months after RT. ■ Characterized by diffuse alveolar damage and infiltration of macrophages ■ CT appearance: ground-glass opacities, consolidation, or both in radiation port ■ May resolve gradually or progress to fibrosis (6–12 months after radiation) ■ On PET, there may be corresponding mild to intense FDG uptake. ■ Increased FDG uptake should decrease over time, but mild uptake can persist in chronic fibrosis. ■ Appearance and timing is reported to be generally similar after 3D conformal radiation and stereotactic body radiotherapy, which includes a smaller volume of irradiated tissue.

▶ The timing of the PET scan after radiation, location of the findings in regard to the radiation port and primary tumor, and evolution over time are important considerations for distinguishing post-radiation changes from recurrent or residual tumor. Biopsy may be needed in some cases.

Management ▶ Reassessment by medical and radiation oncology for further treatment of the subcarinal mass ▶ Symptomatic treatment of the radiation pneumonitis (i.e., steroids). Further Readings Domachevsky L, et al. Postradiation changes in tissues. PET Clin. 2014;9:215–235. Larici AR, et al. Lung abnormalities at multimodality imaging after radiation therapy for non–small cell lung cancer. Radiographics. 2011;31:771–789.

224

Case 106 History ▶ A 75-year-old woman with history of Hodgkin lymphoma post-splenectomy, chemotherapy, and

mediastinal radiotherapy 14 years ago. Shortly after the completion of radiotherapy, she developed a persistent left pleural effusion.

Figure 106.1 

Figure 106.2 

Figure 106.3 

225

Case 106  Pleural Talc Crystal Deposits From Pleurodesis

Figure 106.4  Radiopharmaceutical/Dose/Procedure:

Figure 106.5  18F-FDG/10–15

mCi/PET-CT 1 hour after injection.

Findings (Figures 106.1, 106.2, 106.3) ▶ MIP image (Figure 106.1) shows several sites of intense FDG uptake in the left hemithorax, correlating with areas of high attenuation along the pleural surface seen on axial images (Figures 106.2 and 106.3).

▶ A right pleural effusion and loculated pleural fluid along the lateral left upper lobe ▶ Migration of the left kidney into the left upper abdomen post-splenectomy.

Differential Diagnosis ▶ Pleural disease related to talc crystal deposition, asbestos exposure, or malignancy such as lymphoma. Teaching Points ▶ Radiation therapy can result in pleuritis or lymphatic obstruction from mediastinal fibrosis leading to development of a pleural effusion.

▶ A pleural effusion resulting from radiotherapy usually develops within 6 months of therapy and can be treated with talc pleurodesis, where talc crystals cause an inflammatory response leading to fibrosis and tethering of the visceral and parietal pleura. ▶ On CT, pleural talc deposits appear as areas of increased attenuation. Although typically denser talc deposits occur dependently in the pleural space, video-assisted thoracoscopic talc administration can lead to talc deposits in non-dependent areas (as in Figure 106.3). ▶ On FDG-PET, pleural talc deposits are often FDG-avid because of granulomatous inflammation. FDG uptake can be intense and can persist as long as talc crystals are present (over a decade in this case). ▶ The CT appearance of the hemithorax following exposure to talc may be indistinguishable from asbestos. However, asbestos exposure-related pleural plaques are not significantly FDG-avid (Figure 106.4). ▶ FDG-avid talc deposits can have unusual appearances on PET scans (Figure 106.5).

Management ▶ Intensely FDG-avid high attenuation pleural deposits are suspicious for prior talc pleurodesis, and this was confirmed from the medical record.

Further Reading Murray JG, et al. Talc pleurodesis simulating pleural metastases on 18F-fluorodeoxyglucose positron emission tomography. AJR. 1997;168:359–360.

226

Case 107 History ▶ A 36-year-old woman with non-Hodgkin lymphoma. Treated with R-CHOP chemotherapy, ending 6 months prior to restaging FDG-PET/CT scan.

Figure 107.1 

227

Case 107  Thymic Rebound

Figure 107.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intense FDG uptake in a triangular-shaped pattern in the anterior mediastinum. Differential Diagnosis ▶ Physiologic uptake in the thymus ▶ Recurrent lymphoma. Teaching Points ▶ Physiologic thymic uptake on PET has a typical triangular-shaped appearance in the anterior mediastinum.

On combined PET/CT imaging, the FDG uptake fuses to thymic tissue in the anterior mediastinum. In this case, the appearance on PET, time course (6 months after chemotherapy), and no other sites of possible disease favor benign thymic hyperplasia, rather than recurrent lymphoma. ▶ Physiologic thymic uptake and thymic uptake due to hyperplasia after treatment are more frequently seen in children compared to adults. ▶ The frequency and intensity of thymic FDG uptake is lowest during and at the end of chemotherapy and increased in the follow-up period. ▶ Thymic FDG uptake can persist in a significant number of patients for 1–3 years after the completion of therapy.

Management ▶ Continued follow-up per standard of care for non-Hodgkin lymphoma. Further Readings Brink I, et al. Increased metabolic activity in the thymus gland studied with 18F-FDG PET: age dependency and frequency after chemotherapy. J Nucl Med. 2001;42:591–595. Goethals I, et al. Time-dependent changes in 18F-FDG activity in the thymus and bone marrow following combination chemotherapy in paediatric patients with lymphoma. Eur J Nucl Med Mol Imaging. 2010;37:462–467. Jerushalmi J, et al. Physiologic thymic uptake of 18F-FDG in children and young adults: a PET/CT evaluation of incidence, patterns, and relationship to treatment. J Nucl Med. 2009;50:849–853.

228

Case 108 History ▶ A 36-year-old woman with Hodgkin lymphoma post 6 cycles of chemotherapy with doxorubicin, bleomycin, vinblastine, and darcarbacine (ABVD) chemotherapy.

Figure 108.1 

229

Case 108  Post-Therapy Lymphoma

Figure 108.2 

Figure 108.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intense, focal FDG uptake in residual anterior mediastinal soft tissue (Figure 108.2). Differential Diagnosis ▶ Residual metabolically active lymphoma ▶ Physiologic thymic uptake Teaching Points ▶ Residual metabolically active lymphoma is the most likely diagnosis in this case, given the focal nature of the

uptake at a site of known disease at initial staging. Physiologic thymic uptake typically has a triangular-shaped appearance on PET (see Case 107, Thymic Rebound). ▶ Post-therapy PET assessments in patients with lymphoma provide important prognostic information due to the ability to distinguish active lymphoma from fibrosis/necrosis in residual masses on CT. ▶ Progression-free and overall survival is significantly lower in patients with positive versus negative post-therapy PET scans, even if a residual mass is present on CT. ▶ For FDG-avid lymphomas, end-of-treatment assessment is performed with FDG-PET/CT using a 5-point scale (1: ≤background, 2: ≤mediastinal blood pool, 3: >mediastinal blood pool but ≤liver, 4: moderately >liver, 5: markedly >liver and/or new lesions, X: new areas of uptake unlikely representing lymphoma). Scores 1 and 2 are considered a complete metabolic response (Figure 108.3, arrows). A score of 3 generally indicates a good prognosis, however, in some instances may be considered an inadequate response depending on treatment type, timing of PET/CT or clinical trial goals. Scores 4 and 5 are considered inadequate treatment response at the end of therapy. ▶ However, a negative post-therapy PET does not exclude the presence of microscopic disease, and those with PET-negative residual masses are more likely to recur than those without a residual mass.

Management ▶ Consider biopsy to confirm the presence of residual lymphoma and if positive, second-line therapy. Further Readings Cheson BD, et al. Recommendations for initial evaluation, staging, and response assessment of Hodgkin and non-Hodgkin lymphoma: The Lugano Classification. J Clin Oncol. 2014;32(27):3059–3067. Barrington SF, et al. Role of imaging in the staging and response assessment of lymphoma: consensus of the International Conference on Malignant Lymphomas Imaging Working Group. J Clin Oncol. 2014;32(27):3048–3058.

230

Case 109 History ▶ A 46-year-old man with colon cancer post-resection and adjuvant chemotherapy.

Figure 109.1 

231

Case 109 Sarcoidosis

Figure 109.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Symmetric, intense FDG uptake in mediastinal and hilar lymph nodes ▶ Foci of increased FDG uptake in the abdomen fused to postsurgical inflammatory changes in the anterior abdominal wall (arrows, not shown in axial view).

Differential Diagnosis ▶ Sarcoidosis or other inflammatory or infectious process ▶ Lymphoma ▶ Metastatic colon cancer, less likely. Teaching Points ▶ Benign inflammatory and infectious processes can accumulate FDG, for example sarcoidosis, histoplasmosis, tuberculosis, radiation pneumonitis, fractures, or acute infections.

▶ The level of FDG uptake can vary from mild to intense. Chronic infections tend to have lower levels of uptake compared to acute infections.

▶ The pattern of intense and symmetric uptake in the mediastinal and hilar region in the absence of other disease from colon cancer raises the question of another process.

▶ Biopsy is needed for a definitive diagnosis, and in this case biopsy revealed sarcoidosis. Management ▶ Referral for biopsy. Further Readings Lewis PJ, Salama A. Uptake of fluorine-18-fluorodeoxyglucose in sarcoidosis. J Nucl Med. 1994;35:1647–1649. Shreve PD, et al. Pitfalls in oncologic diagnosis with FDG PET imaging: physiologic and benign variants. Radiographics. 1999;19:61–77.

232

Case 110 History ▶ A 78-year-old man with known adenocarcinoma of the esophagus undergoing FDG-PET/CT at the time of initial evaluation in preparation for therapy.

Figure 110.1 

233

Case 110  Lipomatous Hypertrophy of the Interatrial Septum (LHIS)

Figure 110.2  Axial fused PET/CT, CT and FDG-PET images at the level of the atria. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ FDG uptake associated with circumferential esophageal wall thickening (dotted arrows) ▶ FDG-avid adipose tissue in the interatrial septum (solid arrows). Differential Diagnosis ▶ FDG-avid esophageal wall thickening may be due to: ■ Esophageal cancer ■ Inflammation, infection, or metastasis, less likely given the intensity and wall thickening. ▶ FDG uptake associated with LHIS on CT is pathognomonic. Teaching Points ▶ Metabolically active LHIS is characterized by FDG-avid adipose tissue in the interatrial septum. Histologically, it includes mature adipose cells, brown fat, cardiomyocytes, and inflammatory cells. LHIS is often incidentally detected on imaging, although it can infrequently be associated with arrhythmias, or sudden death. ▶ FDG-PET/CT can be helpful for staging esophageal cancer, commonly using the TNM system: T-staging refers to tumor invasion depth but not size or length: ■ T1: Involvement of lamina propria, muscularis mucosea, or submucosa ■ T2: Involvement of the muscularis propria ■ T3: Involvement of the adventitia ■ T4a: Involvement of pleura, peritoneum, pericardium, and diaphragm ■ T4b: Involvement of great vessels, trachea, bronchus, and vertebrae. N-staging refers to number of regional lymph nodes involved periesophageal (cervical to celiac): ■ N1: 1–2 ■ N2: 3–6 ■ N3: 7 or more. M-staging refers to the extent of spread to distant sites: ■ M0: No distant metastases ■ M1: Distant metastasis.

Management ▶ TNM staging can be performed using endoscopic ultrasound, diagnostic CT, and FDG-PET/CT. Tissue biopsy is needed for histologic grading.

▶ There is no intervention needed for FDG-avid LHIS. Further Readings Edge S, et al. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010. Zukotynski K, et al. FDG uptake in lipomatous hypertrophy of the interatrial septum is not likely related to brown adipose tissue. Clin Nucl Med 2011;36:767–769.

234

Case 111 History ▶ A 54-year-old woman with metastatic right breast cancer. PET/CT scans were performed before (left) and after (right) neoadjuvant chemotherapy.

Figure 111.1 

235

Case 111  Breast Cancer With Incidental Pneumonia

Figure 111.2  MIP, axial fused FDG-PET/CT, CT and FDG-PET at the level of the lungs before (left) and after (right) therapy. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Before therapy: ■ FDG-avid right breast skin thickening is consistent with known inflammatory breast cancer. ■ FDG-avid tumor in lymph nodes, liver, and bone significantly improved with therapy. ▶ After therapy: New FDG-avid rounded opacity in the left lung. Differential Diagnosis (After Therapy) ▶ Infection: A bacterial etiology is favored, although a fungal infection is possible. ▶ Malignancy: The new FDG-avid left lung opacity could be recurrent tumor, although this is unlikely given interval improvement in tumor burden elsewhere with therapy.

Teaching Points ▶ FDG-PET/CT: ■ Can be helpful for breast cancer staging and subsequent treatment strategy ■ Cannot replace sentinel lymph node evaluation for staging ■ Can contribute to improved understanding of tumor biology and effects of therapy ■ Can predict risk for early relapse, when performed during neoadjuvant chemotherapy. Metabolic nonresponders are more likely to have residual disease and early relapse.

▶ In the case above, the staging FDG-PET/CT showed widespread metabolically active disease in the right

breast, lymph nodes, liver, and bone, but no FDG-avid lung disease. On short interval follow-up FDG-PET/ CT after therapy, the FDG-avid disease in the breast, lymph nodes, liver, and bone at baseline had almost resolved. The new FDG-avid pulmonary opacity is most likely due to an alternate metabolic process, and infection should be considered.

Management ▶ Clinical correlation and follow-up imaging to resolution is needed. Further Readings Groheux D, et al. Triple-negative breast cancer: early assessment with 18F-FDG PET/CT during neoadjuvant chemotherapy identifies patients who are unlikely to achieve a pathologic complete response and are at a high risk of early relapse. J Nucl Med. 2012;53:249–254. Lee SM, et al. Value of 18F-FDG PET/CT for early prediction of pathologic response (by Residual Cancer Burden Criteria) of locally advanced breast cancer to neoadjuvant chemotherapy. Clin Nucl Med. 2014;39(10):882–886. Niikura N, et al. FDG-PET/CT compared with conventional imaging in the detection of distant metastases of primary breast cancer. Oncologist. 2011;16(8):1111–1119.

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Case 112 History ▶ A 37-year-old woman with a history of stage IIIB Hodgkin disease following six cycles of ABVD chemotherapy returning for follow-up after 54 months in complete remission.

Figure 112.1 

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Case 112 Metabolically Active Glandular Tissue in a Lactating Patient Who Is Breastfeeding

Figure 112.2 

Figure 112.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Diffuse symmetric intense FDG uptake in the glandular tissue of both breasts (Figure 112.2). Differential Diagnosis ▶ Breastfeeding ▶ Mastitis ▶ Malignancy such as lymphoma. Teaching Points ▶ Normal breast glandular tissue typically exhibits low-level FDG uptake. ▶ Both mastitis and malignancy would be more likely in the setting of unilateral FDG-avid breast tissue. ▶ Intense FDG uptake associated with lactating breast tissue is thought to relate to the increased expression of

glucose transporter proteins stimulated by suckling. ■ Typically, there is symmetric bilaterally increased FDG uptake in women who breastfeed on both sides. ■ Increased FDG uptake in only one breast of a lactating woman can be observed (Figure 112.3), and is usually in the setting of protracted exclusive use of that particular breast for nursing, with loss or reduction of metabolic activity in the unused breast.

Management ▶ Patients are instructed to avoid breastfeeding and express but discard their breast milk for 24 hours after the

PET/CT study. This is done to reduce radiation exposure to the infant from close proximity to radiotracer in the breast tissue and the small amount of radiotracer excreted into the breast milk.

Further Reading Hicks RJ et al. Pattern of uptake and excretion of F-18 FDG in the lactating breast. J Nuc Med. 2001;42:1238–1242.

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Part 8

PET/CT in Oncology II Katherine A. Zukotynski, Christopher G. Sakellis, Chun K. Kim, Heather A. Jacene

Case 113 History ▶ A 78-year-old man with esophageal cancer and an 83-year-old man with esophageal cancer, both

undergoing FDG-PET/CT at the time of initial evaluation in preparation for therapy. MIP images in these two patients are shown in Figure 113.1. Which patient is most likely to have squamous cell carcinoma, and which is most likely to have adenocarcinoma?

A

B

Figure 113.1  MIP images from two FDG-PET/CT studies in two different patients.

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Case 113  Esophageal Cancer A

B

Figure 113.2  MIP images from two FDG-PET/CT studies in two different patients. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Both patients have metastatic FDG-avid esophageal carcinoma. ▶ Patient A has FDG-avid esophageal carcinoma (Figure 113.2; thick arrow) involving the distal esophagus

associated with FDG-avid paraesophageal adenopathy (dotted arrow) and osseous disease (thin solid arrow).

▶ Patient B has FDG-avid esophageal carcinoma (arrow) involving the mid-esophagus associated with widespread FDG-avid metastatic disease involving lymph nodes, liver, lung, and skeleton.

Differential Diagnosis ▶ Both patients have known esophageal carcinoma. The histologic differential diagnosis is adenocarcinoma versus squamous cell carcinoma.

Teaching Points ▶ Squamous cell carcinoma is more common in the developing world and in the mid- to distal esophagus, while adenocarcinoma is more common in Caucasian men and in the distal esophagus.

▶ FDG-PET/CT is used to detect distant metabolically active disease in patients with esophageal cancer at the time of staging. The most common staging system for esophageal cancer is the TNM staging system (see Case 110). ▶ The treatment for esophageal cancer has improved over the years: ■ ~ 4% survived at least 5 years from diagnosis in the 1960s. ■ ~ 18% survive at least 5 years from diagnosis today.

Management ▶ TNM staging can be performed using endoscopic ultrasound, diagnostic CT, and FDG-PET/CT. Tissue biopsy is needed to ascertain the histologic grade of the esophageal cancer.

Further Reading Edge S, et al. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010.

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Case 114 History ▶ FDG-PET/CT was performed for evaluation of recurrence in the remnant stomach in two patients post-subtotal gastrectomy for gastric carcinoma. MIP images in these two patients are shown in Figure 114.1.

A

B

Image courtesy of Mijin Yun, MD, Yonsei University, Seoul, Korea.

Figure 114.1 

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Case 114 Physiologic Gastric Uptake and Recurrent Gastric Carcinoma A

B

After drinking

After drinking

Figure 114.2  MIP images in two patients before and after drinking water. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection, repeat imaging of the upper abdomen after drinking water (as much as possible > 300 mL).

Findings ▶ Patient A: Initially increased FDG uptake in remnant stomach disappears after water ingestion causing gastric distention, suggestive of physiological gastric uptake.

▶ Patient B: Increased FDG uptake in remnant stomach persists despite gastric distention by water ingestion, suggestive of recurrence.

Differential Diagnosis ▶ Prominent physiological gastric uptake ▶ Recurrent cancer. Teaching Points ▶ FDG avidity of gastric carcinoma varies: ■ Depending on the degree of differentiation of tumor ■ Mucinous adenocarcinomas and signet ring type carcinomas are generally less FDG avid. ▶ Physiological gastric uptake of FDG also varies widely (see also figures in Case 91) and may sometimes be

similar to or higher than tumor uptake. Therefore, evaluation of gastric carcinoma with FDG-PET/CT can be difficult, especially in the setting of small gastric remnant. ▶ Gastric distention by water ingestion is a useful maneuver, as shown in these two cases.

Management ▶ Patient B was found to have no other metastatic disease and underwent resection of recurrent tumor. Further Reading Yun M, et al. The role of gastric distention in differentiating recurrent tumor from physiologic uptake in the remnant stomach on 18F-FDG PET. J Nucl Med. 2005;46:953–957.

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Case 115 History ▶ A 76-year-old man with gastrointestinal stromal tumor (GIST) and mental deterioration underwent

whole body FDG-PET/CT for staging. A MIP image and selected axial PET and PET/CT slices of the brain are shown in Figure 115.1.

Figure 115.1 

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Case 115  Attenuation Artifact Due to Patient Motion AC

NAC

AC

Figure 115.2 

NAC

Figure 115.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ MIP image: Innumerable FDG-avid lesions in the chest, abdomen/pelvis including the liver, adrenal gland, mesentery/omentum, and skeleton (Figures 115.1 and 115.2).

▶ Attenuation corrected (AC) image: Increased uptake in the left cerebral/cerebellar hemisphere and right frontal lobe (decreased uptake in the right temporal lobe and cerebellum)

▶ Marked mis-registration of PET and CT images ▶ Non-attenuation corrected (NAC) image: Symmetrical uptake (with relatively decreased activity in the deeper portion of the brain due to higher attenuation).

Differential Diagnosis (for the Brain PET Finding) ▶ Vascular disease ▶ Encephalitis ▶ Seizure focus (right temporal if interictal, or left with propagation if ictal). Teaching Points ▶ Given the geographic pattern and distribution of tracer activity (encompassing different vascular territories,

different lobes, and cerebrum and cerebellum), none of the differential diagnoses listed above would be likely.

▶ The PET and CT data are acquired separately. Since CT is used for attenuation correction, mis-registered PET and CT due to patient motion will result in artifacts on the AC images. ■ Tracer activity registered to the outside of the body or superficial portion of the body on CT (e.g., right temporal and cerebellum in this case) will be under-corrected, whereas tracer activity registered to the deeper portion of the body on CT (e.g., left frontal) will be over-corrected. ▶ Even if patient does not move, attenuation artifacts due to respiratory motion are commonly seen in the diaphragm region. ■ For example (Figure 115.3), a lesion in the hepatic dome may appear as a lung base lesion on the AC images. While this finding may be correctly interpreted based on the combination of PET and CT findings, remember that the SUV of such lesions is underestimated. ▶ Whenever the presence of attenuation artifacts is suspected, NAC images must be reviewed. ▶ The same issues apply to SPECT imaging if CT is used for AC.

Management ▶ The patient was placed on palliative therapy for widespread GIST. Further Reading Sureshbabu W, et al. PET/CT Imaging Artifacts. J Nucl Med Technol. 2005;33:156–161.

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Case 116 History ▶ A 65-year old patient with hematochezia and abdominal distention underwent colonoscopy that

revealed a large obstructive mass in the sigmoid colon. The rest of the colon proximal to the mass could not be examined, as colonoscopy could not traverse the obstructive lesion. The mass was found to be adenocarcinoma. FDG-PET/CT was performed for staging.

Figure 116.1  MIP image and two selected axial fused PET/CT images.

247

Case 116 Metastatic Sigmoid Colon Cancer With a Synchronous Colon Cancer

Figure 116.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intense FDG uptake in the known sigmoid cancer (red arrow) ▶ Intense focal FDG uptake in the proximal descending colon (blue arrow) ▶ Multiple FDG-avid liver lesions ▶ Linear uptake in the sternum due to prior median sternotomy. Differential Diagnosis (for the Second Small Lesion) ▶ Synchronous carcinoma ▶ Adenoma. Teaching Points ▶ FDG-PET/CT plays no role for the diagnosis of primary colon carcinoma or T staging and has a limited role

for N staging. However, FDG-PET/CT is valuable for M staging and therapy response evaluation. FDG-PET/ CT can also be helpful for detecting the source of malignancy in the setting of suspected recurrent colorectal cancer and a rising CEA. ▶ Although FDG-PET/CT is not routinely performed for preoperative staging, it can be helpful in selected patients. For example, when complete endoscopic evaluation is not possible, as in this case, or the patient is a poor surgical candidate. ▶ The incidence of synchronous colorectal cancer is reported to be 4.6%–10.7%. ▶ Preoperative detection of a synchronous lesion is essential for optimal surgical planning and treatment.

Management ▶ The surgical approach was altered and the extent of colon resection was increased due to the FDG-PET/CT finding.

Further Readings Cunliffe WJ, et al. Incidence of synchronous and metachronous colorectal carcinoma. Br J Surg. 1984;71:941–943. Mori S et al. Application of 18F-fl uorodeoxyglucose positron emission tomography to detection of proximal lesions of obstructive colorectal cancer. Jpn J Radiol. 2010;28:584–590. Oya M, et al. Synchronous colorectal carcinoma: clinico-pathological features and prognosis. Jpn J Clin Oncol. 2003;33:38–43.

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Case 117 History ▶ A 44-year-old woman with metastatic disease from unknown primary (Figure 117.1).

Figure 117.1  MIP image, axial fused FDG-PET/CT, CT and FDG-PET at the level of the lungs, liver, and colon.

249

Case 117  Colon Cancer (Unknown Primary)

Figure 117.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intensely FDG-avid rectosigmoid colon mass ▶ Intensely FDG-avid hepatic disease ▶ FDG-avid mesenteric lymph node ▶ FDG-avid pulmonary nodule. Differential Diagnosis ▶ The FDG-avid rectosigmoid colon mass is likely the site of primary disease with metastases to the liver, mesenteric lymph node, and lung.

▶ Primary hepatic malignancy is unlikely because this is more likely to be mildly FDG-avid on FDG-PET and would be unlikely to have this pattern of metastatic disease.

▶ Primary lung cancer is also unlikely given the small size of the pulmonary nodule and the distribution of FDG-avid metastatic disease elsewhere.

Teaching Points ▶ Colon cancer is the third most commonly diagnosed cancer and the third leading cause of cancer-related mortality in both men and women in the United States.

▶ FDG-PET/CT can be very helpful in the evaluation of distant metastatic disease associated with colorectal cancer and in the assessment of suspected recurrent malignancy.

▶ False-negative results can occur, particularly with mucinous adenocarcinoma. ▶ Care must be taken to avoid false-positive interpretations by confounding malignancy with inflammation associated with diverticulitis and/or postoperative change.

Management ▶ The above patient has extensive metastatic colon cancer with disease to the liver, lymph nodes, and lungs. She was treated with chemotherapy and had significant improvement in her disease.

Further Readings Akiyoshi T, et al. Comparison of preoperative whole-body positron emission tomography with MDCT in patients with primary colorectal cancer. Colorectal Dis. 2009;11:464–469. O’Connor OJ, et al. The use of PET/CT in the assessment of patients with colorectal carcinoma. Int J Surg Oncol. 2011;2011:846512.

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Case 118 History ▶ A 52-year-old woman with squamous cell carcinoma of the tongue, for initial staging evaluation.

Figure 118.1  Axial FDG-PET, CT, and fused FDG-PET/CT at the level of the left adrenal gland.

251

Case 118  Incidental Adrenal Adenoma

Figure 118.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Mildly FDG-avid left adrenal gland mass (arrows) Differential Diagnosis ▶ Adrenal adenoma, most likely given the low CT density and mild FDG uptake ▶ Metastatic disease or primary adrenal malignancy, unlikely. Teaching Points ▶ Nonfunctioning adrenal adenomas are common benign incidental findings on CT. ▶ On non-contrast CT, adrenal adenomas are often sharply defined, round masses < 3 cm with low density.

A mean attenuation value < 10 HU has specificity 98% and sensitivity 71% for an adrenal adenoma, where the region of interest is within the central one-half to two-thirds of the mass, excluding internal calcification or necrosis. ▶ On contrast-enhanced CT, enhancement is often uniform and washout is faster in benign adenomas than metastasis when immediate post-contrast images are compared with delayed images (10–15 minutes after contrast administration). ■ The relative percentage enhancement washout can be calculated as [the immediate post-contrast enhanced attenuation minus the delayed enhanced attenuation] divided by the immediate post-contrast enhanced attenuation. ■ A relative percentage washout > 40%–50% is highly suggestive of an adenoma. ▶ On MRI, a benign adrenal adenoma will typically show signal dropout or, in other words, a distinct decrease in signal intensity on out-of-phase images compared with in-phase images. ▶ On FDG-PET, the uptake in a benign adrenal adenoma is often mild. ▶ Lesions that are incompletely characterized on washout CT, MRI, or FDG-PT require image-guided percutaneous biopsy.

Management ▶ Washout diagnostic CT or MRI could be used to confirm the diagnosis of an adrenal adenoma. Further Readings Webb WR, et al. Fundamentals of Body CT. 3rd ed. Philadelphia: Saunders Elsevier; 2006. Yun M, et al. 18F-FDG PET in characterizing adrenal lesions detected on CT or MRI. J Nucl Med. 2001;42:1795–1799.

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Case 119 History ▶ A 50-year-old man with an incidental renal lesion detected at the time of staging FDG-PET/CT for lung cancer.

Figure 119.1  

253

Case 119  Incidental Renal Cell Carcinoma

Figure 119.2  Axial FDG-PET, CT, and fused FDG-PET/CT at the level of the kidneys.

Figure 119.3  RCC with mild FDG uptake incidentally found on a PET/CT performed in another patient for staging of lymphoma. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Mildly FDG-avid mass arising from the left kidney (Figure 119.2; blue arrow). Differential Diagnosis ▶ Renal cell carcinoma, most likely given the mild FDG uptake ▶ Metastatic lung cancer to the kidney, less likely given the mild FDG uptake. Teaching Points ▶ It is estimated that the majority of renal cell carcinomas (RCC) are detected incidentally. ▶ There are several histologic subtypes of RCC including clear cell RCC (70%), papillary RCC (15%), chromophobe RCC, collecting duct (Bellini duct) carcinoma, and unclassified tumors.

▶ Surgery is the mainstay of treatment, although radiofrequency ablation or cryoablation are options and may be preferable for patients with comorbidities or limited life expectancy.

▶ RCC can be intensely FDG-avid or only mildly FDG-avid, similar to normal renal parenchyma. A mildly FDG-avid soft tissue renal mass is highly suspicious for RCC (Figures 119.2 and119.3).

▶ Several different primary malignancies can spread to the kidneys, such as lung cancer, breast cancer, colon cancer, and melanoma.

▶ Lung metastases to the kidney are typically intensely FDG-avid and present as either a solitary parenchymal nodule or as several small multicentric lesions.

Management ▶ Tissue biopsy is needed to ascertain the histologic diagnosis. Further Reading Zhang J, et al. Imaging of kidney cancer. Radiol Clin N Am. 2007;45:119–147.

254

Case 120 History ▶ A 77-year-old woman with chief complaint of perineal bleeding for 3 months. Pelvic ultrasound

revealed cervical and endometrial masses, enlarged and heterogeneous ovaries, and left adnexal mass of unclear etiology.

MIP

Figure 120.1  

255

Case 120  Metastatic Cervical Cancer (Stage IVB) A

B

C

MIP

D

Figure 120.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Large FDG-avid pelvic mass (D) involving the uterine body, cervix, and both adnexa. ▶ Extensive lymphadenopathy: left supraclavicular (Virchow) (A), retroperitoneal (B), and pelvic (C). ▶ Metastatic disease involving the liver, left adrenal gland, and multiple bones. Differential Diagnosis ▶ Metastatic cervical cancer ▶ Metastatic uterine cancer. Teaching Points ▶ For staging of cervical cancer, the FIGO (International Federation of Gynecology and Obstetrics) system is

most commonly used. In the FIGO system, Stages I through IVA are primarily determined by the T stages with the N and M stages being 0, with an exception of Stage IIIB that may be either T3b/N0/M0; or T1-3/N1/ M0. Stage IVB represents any T/any N/M1 (see Further Readings for more details). ▶ In locally advanced cervical cancer, FDG-PET/CT: ■ Has become an important tool in the initial evaluation of lymph node status and distant metastases, particularly for clinical stage IIB and higher. ■ Provides prognostic information. A higher level of FDG avidity in the primary lesion and regional lymph nodes is predictive of poorer outcome. ■ Is useful for assessing response after chemoradiotherapy and predicting long-term survival. ■ Is useful for radiotherapy planning.

Management ▶ Histopathology revealed cervical carcinoma. ▶ Palliative radiation therapy was initiated. Further Readings Benedet JL, et al. FIGO staging classifications and clinical practice guidelines in the management of gynecologic cancers. FIGO Committee on Gynecologic Oncology. Int J Gynaecol Obstet. 2000;70:209–262. Grant P, et al. Gynecological oncologic imaging with PET/CT. Semin Nucl Med. 2014;44(6):461–478. Herrera FG, Prior JO. The role of PET/CT in cervical cancer. Front Oncol. 2013;3:34.

256

Case 121 History ▶ A 47-year-old perimenopausal woman with recently diagnosed cervical cancer following cone biopsy.

Figure 121.1 

257

Case 121  Metabolically Active Corpus Luteum Cyst in the Right Ovary

Edge of bladder

Figure 121.2  MRI correlating to Figure 121.1.

Figure 121.3  Companion case.

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Figure 121.1: Intense focal uptake in the right adnexa, correlating with a hypodense structure along the right pelvic sidewall

▶ MRI: T2-weighted (top), T1 with Gadolinium (bottom): ■ The round structure in the right adnexa containing cysts represents the right ovary. The smaller T2-bright/ T1-dark structure within the ovary likely represents a physiologic cyst, while the larger structure, which is less T2-bright and T1-dark with an enhancing rim, represents a corpus luteum cyst (CLC). ■ The left ovary containing a T2-bright physiologic cyst is also present at the same level.

Differential Diagnosis ▶ Metastatic cervical cancer to a right external iliac lymph node or ovary ▶ Ovarian cancer. Teaching Points ▶ A corpus luteum cyst is a functional ovarian cyst that forms after an egg has been released from a follicle and occurs in the secretory phase of a premenopausal patient.

▶ Corpus luteum cysts are often moderately to intensely FDG-avid and are indistinguishable on PET/CT from malignancy, either involving the ovary or a nearby lymph node. ■ Figure 121.3 shows a 52-year-old woman with rectal cancer and intense FDG uptake in the right adnexa (long arrow). Laparoscopic surgery revealed metastatic colon cancer involving the right ovary.

Management ▶ Clinical correlation with the time of the menstrual cycle is helpful, although a follow-up PET/CT scan could be performed during the ovulatory phase to establish resolution of the FDG uptake.

▶ MRI is recommended in: ■ Perimenopausal women (like the one presented above) in whom menstrual cycles are often irregular ■ Postmenopausal women ■ Any patients where clinical suspicion remains high for metastatic disease. Further Reading Ho K-C, et al. An ovary in luteal phase mimicking common iliac lymph node metastasis from a primary cutaneous peripheral primitive neuroectodermal tumour as revealed by 18-fluoro-2-deoxyglucose positron emission tomography. British J Rad. 2005;78:343–345.

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Case 122 History ▶ A patient underwent FDG-PET/CT with intravenous contrast enhancement for restaging of

malignancy. The maximum intensity projection and selected axial images showed bilateral pelvic foci of increased FDG uptake (arrows, Figure 122.1). The finding MOST likely represents?

Figure 122.1 

259

Case 122  Physiologic Uptake in Fallopian Tubes and Endometrium

Figure 122.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT (contrast-enhanced) 1 hour after injection of FDG.

Findings ▶ Finding 1: Bilateral tubular moderately increased FDG uptake along the pelvic sidewall corresponding to the fallopian tubes

▶ Finding 2: Mildly increased FDG uptake within the uterus. Differential Diagnosis ▶ Finding 1: ■ Recurrent malignant disease ■ Corpus luteum cysts ■ Urine activity in the distal ureters. ▶ Finding 2: ■ Endometrial cancer ■ Menstruation. Teaching Points ▶ Finding 1: ■ While recurrent disease would be a consideration on PET alone, CT suggests this is unlikely. ■ Corpus luteum cyst is generally unilateral. ■ Correlation of the PET and CT images shows that the FDG activity is not in the distal ureters. ■ Physiologic 18F-FDG uptake in the fallopian tubes can be seen in premenopausal women around their

mid-menstrual cycle, likely representing the known cyclic changes of the fallopian tubes in response to estrogen.

▶ Finding 2: ■ In premenopausal women, increased FDG uptake can be seen during the ovulatory and menstrual phases in normal endometrium.

▶ Increased FDG uptake in the uterus and/or ovary in postmenopausal women should not be interpreted as normal variants, and further evaluation is needed.

Management ▶ None. Further Readings Lerman H, et al. Normal and abnormal 18F-FDG endometrial and ovarian uptake in pre- and postmenopausal patients: assessment by PET/CT. J Nucl Med. 2004;45:266–271. Yun M, et al. Physiologic 18F-FDG uptake in the fallopian tubes at mid cycle on PET/CT. J Nucl Med. 2010;51:682–685.

260

Case 123 History ▶ A 46-year-old woman with ovarian cancer post-optimal cytoreductive surgery and chemotherapy. Recent CA-125 levels are in the normal range, but rising.

Figure 123.1 

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Case 123  Ovarian Cancer and Rising CA-125

Figure 123.2 

Figure 123.3 

Radiopharmaceutical/Dose/Procedure:

18F-FDG/10–15

Figure 123.4  mCi/PET-CT 1 hour after injection.

Findings ▶ Moderate FDG uptake fusing to a < 1 cm nodule in the left paracolic gutter (Figure 123.2; arrows). Differential Diagnosis ▶ Recurrent ovarian cancer ▶ Postoperative inflammatory changes. Teaching Points ▶ FDG-PET/CT is very useful for detecting recurrent ovarian cancer, particularly in the setting of rising CA-125 and negative or equivocal CT.

▶ FDG-PET/CT can help to identify patients with localized disease who might benefit from surgery and who have a better prognosis compared to those with diffuse disease (Figure 123.3).

▶ In contrast to this patient, peritoneal carcinomatosis describes diffuse metastases throughout the peritoneal cavity, which is also a pattern of recurrence in ovarian cancer. ■ Typically seen on CT as nodular implants on or thickening of the peritoneal surfaces (Figure 123.4); presence of ascites raises the concern for peritoneal seeding. ■ FDG uptake on PET/CT can have variable intensity in the lesions and may be diffuse, focal, or both. ■ Examination of both the PET and CT portions of the exam is mandatory. ■ Both CT and FDG-PET/CT may miss tiny implants due to their small size.

Management ▶ Referral to gynecologic oncology for further management of recurrent disease. Further Reading Son H, et al. Role of FDG PET/CT in staging of recurrent ovarian cancer. Radiographics. 2011;31(2):569–583.

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Case 124 History ▶ A 54-year-old man with right gluteal pain and history of lung cancer.

Figure 124.1 

263

Case 124  Synovial Sarcoma

Figure 124.2  Axial fused FDG-PET/CT, CT, and FDG-PET at the level of the gluteus muscles. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intensely FDG-avid mass infiltrating the right gluteus maximus muscle. Differential Diagnosis ▶ Sarcoma ▶ Soft tissue metastatic disease from lung cancer. ▶ Traumatic injury ▶ Infection. Teaching Points ▶ Synovial sarcoma constitutes approximately 10% of all sarcomas and typically involves the lower extremities of patients in the third to fifth decade of life.

▶ MRI has excellent soft tissue contrast and is the imaging modality of choice to evaluate the primary site of disease.

▶ FDG-PET/CT is sensitive for the detection of soft tissue sarcoma, although slightly lower sensitivities have

been reported for synovial sarcoma compared with other histological subtypes (synovial sarcoma (80%), liposarcoma (89%), Ewing sarcoma (100%), gastrointestinal stromal tumors (100%)). The appearance of FDG uptake on PET/CT is not specific for synovial sarcoma and tissue sampling is needed to make the diagnosis. ▶ Increased intensity of FDG uptake on baseline imaging suggests decreased disease-free survival, increased risk of local recurrence, and metastatic disease.

Management ▶ Tissue diagnosis revealed that this was a synovial sarcoma of the right gluteal region. Further Readings Charest M, et al. FDG PET/CT imaging in primary osseous and soft tissue sarcomas : a retrospective review of 212 cases. Eur J Nucl Med Mol Imaging. 2009;36(12):1944–1951. Lisle JW, et al. Risk assessment based on FDG-PET imaging in patients with synovial sarcoma. Clin Orthop Relat Res. 2009;467(6):1605–1611. Zukotynski KA, Kim CK. Sarcoma. In: Gerbaudo VH, ed. A Case-Based Approach to PET/CT in Oncology. Cambridge: Cambridge University Press; 2012:466–486.

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Case 125 History ▶ A 73-year-old woman with history of solitary L5 plasmacytoma 3 years prior post-corpectomy and

radiation. Enlarging lytic lesion in L3 on CT. Ductal carcinoma in situ (DCIS) of the left breast postmastectomy 10 years prior.

A

B

C

Figure 125.1 

265

Case 125  Multiple Myeloma A

B

C

Figure 125.2 

Figure 125.3 

Figure 125.4 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Multiple, scattered foci of intense FDG uptake in the bones (Fig. 125.2A; arrows) ▶ Intensely FDG-avid lytic lesion in L3 (Figure 125.2B) ▶ Intense focus of FDG uptake in the left distal femur with no associated lytic lesion (Figure 125.2C);

corresponding soft tissue window shows asymmetric soft tissue in the marrow cavity corresponding to the intense FDG uptake (Figure 125.3, arrow).

Differential Diagnosis ▶ Multifocal multiple myeloma ▶ Metastatic breast cancer. Teaching Points ▶ Multifocal multiple myeloma is the most likely diagnosis given time course, lytic appearance, and remote

history of DCIS with low risk of bone metastases. Biopsy confirmed multiple myeloma with CD138+ plasma cells. ▶ Active multiple myeloma is typically an FDG-avid tumor. ▶ Metabolic changes from marrow involvement of myeloma may be seen earlier than lytic bone changes on anatomic imaging (Figure 125.2C). ▶ Roles of FDG-PET/CT in the evaluation of patients with multiple myeloma: ■ Staging: Evaluation of disease extent and for extraosseous lesions (Figure 125.4, extensive marrow involvement with extraosseous muscle lesion, left lateral proximal lower extremity) ■ Differentiating monoclonal gammopathy of undetermined significance and smoldering myeloma (low-level FDG uptake or negative) from active myeloma (higher levels of FDG uptake), risk stratification ■ Monitoring response to systemic therapy ▶ Extraosseous myeloma is associated with younger age, more aggressive myeloma subtypes (nonsecretory, IgD), and a poor prognosis. Any organ may be involved.

Management ▶ Referral to medical oncology for systemic treatment of multifocal multiple myeloma. Further Readings Bartel TB, et al. F18-fluorodeoxyglucose positron emission tomography in the context of other imaging techniques and prognostic factors in multiple myeloma. Blood. 2009;114(10):2068–2076. Even-Sapir E. PET/CT in malignant bone disease. Semin Musculoskelet Radiol. 2007;11(4):312–321. Hall MN, et al. Imaging of extraosseous myeloma: CT, PET/CT, and MRI features. AJR. 2010;195(5):1057–1065.

266

Case 126 History ▶ A man with history of lymphoma underwent a FDG-PET/CT scan for subsequent treatment strategy. The maximum intensity projection image and three selected transaxial images of the lower pelvis are shown in Figure 126.1.

Figure 126.1 

267

Case 126 Undescended Testis and Metformin-Associated Colonic Uptake

Figure 126.2  Radiopharmaceutical/Dose/Procedure:

Figure 126.3  18F-FDG/10–15

mCi/PET-CT 1 hour after injection.

Findings (Figure 126.2) ▶ Finding 1: Focally increased FDG uptake in a circumscribed, round soft tissue structure in the right inguinal canal (solid arrows).

▶ Finding 2: Diffusely increased colonic FDG uptake. Differential Diagnosis ▶ Finding 1: Recurrent lymphoma ▶ Finding 2: Colitis. Teaching Points ▶ Physiologic testicular FDG uptake: ■ Testes often show increased FDG uptake (Figure 126.3). Physiological FDG uptake in the testes declines

with age. According to the literature, the SUV gradually decreased from 2.81 ± 0.43 for 30–39-year-old men to 2.18 ± 0.45 for 80–89-year-old men. ■ Undescended testis with increased FDG uptake may mimic malignancy. Careful review of the CT images and identifying only one testis in the proper location will help avoid incorrect interpretation. ▶ Metformin typically results in intense diffuse FDG uptake throughout the colon without a correlating CT abnormality, although colonic activity in patients on metformin can be variable both in intensity and pattern.

Management ▶ None. Further Readings Kitajima K, et al. Normal uptake of 18F-FDG in the testis: an assessment by PET/CT. Ann Nucl Med. 2007 Sep;21(7):405–410. Zukotynski K, Kim CK. Abdomen: normal variations and benign conditions resulting in uptake on FDG-PET/CT. PET Clin. 2014;9:169–183.

268

Case 127 History ▶ A 24-year-old woman with newly diagnosed Hodgkin lymphoma (Figure 127.1).

Figure 127.1 

269

Case 127  Lymphoma Staging

Figure 127.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Intense FDG uptake in anterior mediastinal, axillary, and supraclavicular lymphadenopathy ▶ Moderately increased FDG uptake in a normal-sized celiac axis lymph node (middle row) ▶ Moderately increased FDG uptake in asymmetric soft tissue in the right lower abdominal wall (bottom row) ▶ Diffuse, homogeneous bone marrow uptake. Differential Diagnosis ▶ Lymphoma involving mediastinal, axillary, supraclavicular, and celiac axis lymph nodes and right lower abdominal wall

▶ Diffuse, homogeneous marrow uptake ■ Reactive ■ Lymphomatous involvement, less likely. Teaching Points ▶ FDG-PET/CT is more sensitive and specific than FDG-PET and CT alone for the initial staging of lymphoma, including nodal and extranodal disease.

▶ The improved accuracy of FDG-PET for nodal staging in lymphoma is primarily due to the ability of PET to detect disease in normal-sized lymph nodes, liver, spleen, and marrow.

▶ Detection of nodal disease on one versus both sides of the diaphragm is important for the initial staging of

lymphoma by the Ann Arbor Staging System and the subsequent treatment strategy. ■ Stage I: One lymph node group ■ Stage II: ≥ 2 lymph node groups on the same side of the diaphragm ■ Stage III: Lymph node involvement on both sides of the diaphragm ■ Stage IV: Involvement of ≥ 1 extralymphatic organs, including liver, marrow, or lungs ▶ FDG-PET/CT and biopsy are complementary techniques for evaluation of the bone marrow in patients with lymphoma. At the time of presentation, diffuse, homogeneous FDG uptake in the bone marrow and spleen that is significantly less than that in the nodal tumor is more likely due to reactive changes and not bone marrow infiltration of disease, particularly in the aggressive lymphoma subtypes (i.e., Hodgkin and diffuse large B-cell lymphoma). Focal or intense uptake similar to that of the nodal disease should be considered suspicious for active lymphoma.

Management ▶ Systemic chemotherapy for Stage III Hodgkin lymphoma. Further Readings Salaun PY, et al. Analysis of 18F-FDG PET diffuse bone marrow uptake and splenic uptake in staging of Hodgkin's lymphoma: a reflection of disease infiltration or just inflammation? Eur J Nucl Med Mol Imaging. 2009;36:1813–1821. Seam, et al. The role of FDG-PET scans in patients with lymphoma. Blood. 2007;110:3509–3516.

270

Case 128 History ▶ A 56-year-old woman with history of ovarian cancer for follow-up FDG-PET/CT postchemotherapy and debulking surgery.

Figure 128.1 

271

Case 128  Inflammatory/Reactive Lymph Nodes Due to Flu Shot

Figure 128.2  Axial fused PET/CT, CT, and FDG-PET images at the level of the upper chest. MIP image.

Figure 128.3  Same axial images 3 months later without interval therapy. Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Figure 128.2: FDG-avid right axillary lymphadenopathy and no FDG-avid disease elsewhere. ▶ Figure 128.3: On follow-up images 3 months later without interval therapy, the FDG-avid axillary lymph nodes have resolved.

Differential Diagnosis ▶ Metastatic lymphadenopathy; however, this is unlikely given the location of the primary disease. Teaching Points ▶ Influenza vaccination may lead to FDG uptake in lymph nodes. ▶ Reactive FDG-avid lymph nodes can be indistinguishable from FDG-avid lymph nodes due to malignancy.

Reactive FDG-avid lymph nodes are more likely if any one of the following conditions exist: ■ The site of FDG-avid lymph nodes in the axilla is out of keeping with the expected site of metastatic disease from the known primary. ■ The morphologic appearance of lymph nodes on CT is suggestive of a benign etiology, e.g., fatty hilum. ■ There is a history of recent vaccination on the side of the FDG-avid lymph nodes. ■ There is focal FDG uptake in the deltoid muscle (likely from inflammation at the injection site).

Management ▶ Clinical correlation and follow-up imaging are needed for further evaluation. Further Readings Panagiotidis E, et al. FDG uptake in axillary lymph nodes after vaccination against pandemic (H1N1). Eur Radiol. 2010;20:1251–1253. Thomassen A, et al. Duration of 18F-FDG avidity in lymph nodes after pandemic H1N1v and seasonal influenza vaccination. Eur J Nucl Med Mol Imaging. 2011;38:894–898.

272

Case 129 History ▶ A 59-year-old man with transformed follicular non-Hodgkin lymphoma. Received three cycles of

rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Bone marrow biopsy was negative for lymphoma involvement at initial staging. Developed neutropenia and was given pegfilgrastim 3 days prior to this FDG-PET/CT scan.

Figure 129.1 

273

Case 129  Effects of Hematopoietic Stimulating Factors

Figure 129.2 

Figure 129.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings ▶ Figure 129.2: Intense FDG uptake diffusely throughout the bone marrow and in the spleen (arrow). Differential Diagnosis ▶ Reactive bone marrow and spleen due to the effects of the granulocyte-colony stimulating factor (G-CSF) ▶ Diffuse lymphomatous involvement of the bone marrow and spleen ▶ Diffuse leukemic involvement of the bone marrow and spleen. Teaching Points ▶ Hematopoietic growth factors result in diffusely increased marrow and splenic FDG uptake. This is the most

likely diagnosis in this case given no history of marrow involvement, timing of pegfilgrastim administration, and lack of other FDG-avid sites of disease on the PET/CT. Lymphomatous involvement of the marrow is generally more heterogeneous or multifocal in appearance (two examples in Figure 129.3). ▶ This pattern has been described with G-CSF as well as erythrocyte growth factors for anemia. ▶ Marrow and splenic uptake most intense closest to time of growth factor administration and typically decreases over the next 3–4 weeks. ▶ Malignant disease can be masked by the physiologic response to hematopoietic growth factors. ▶ In the setting of prior disease in the marrow, the pattern of uptake can be more heterogeneous. The “flip-flop” phenomenon has been described in which areas of treated disease are decreased compared to the normal reactive marrow. ▶ Knowledge of when growth factors were administered, if disease was present in the marrow/spleen prior to treatment, comparison to response of the primary tumor and careful evaluation of the marrow on PET and CT are needed for optimal interpretation.

Management ▶ Continued follow-up per standard of care for non-Hodgkin lymphoma. Further Readings Blodgett TM, et al. Diffuse bone marrow uptake on whole-body F-18 fluorodeoxyglucose positron emission tomography in a patient taking recombinant erythropoietin. Clin Nucl Med. 2004;29:161–163. Jacene HA, et al. Effects of pegfilgrastim on normal biodistribution of 18F-FDG: preclinical and clinical studies. J Nucl Med. 2006;47:950–956. Lin EC. FDG PET/CT flip flop phenomenon in treated lymphoma of bone. Clin Nucl Med. 2006;31:803–805. Sugawara Y, et al. Splenic fluorodeoxyglucose uptake increased by granulocyte colony-stimulating factor therapy: PET imaging results. J Nucl Med. 1999;40:1456–1462.

274

Case 130 History ▶ FDG-PET/CT performed to evaluate infection of implantable cardiac defibrillator.

Figure 130.1 

275

Case 130  Attenuation Artifact (Metallic Objects)

AC Attenuation corrected PET

CT

NAC Fused PET/CT

Non-attenuation corrected PET

Figure 130.2 

Figure 130.3 

Radiopharmaceutical/Dose/Procedure: 18F-FDG/10–15 mCi/PET-CT 1 hour after injection.

Findings (Figure 130.2) ▶ Mild to moderate FDG uptake in the left chest wall on the attenuation corrected PET images, fusing to the implantable cardiac defibrillator (ICD).

▶ On the non-attenuation corrected PET image, no FDG uptake is seen in the location of the ICD. ▶ Physiologic FDG uptake in the blood pool. Differential Diagnosis ▶ Attenuation artifact from the ICD (metallic implant) ▶ Inflammation or infection of the ICD. Teaching Points ▶ PET images are reconstructed using corrections for attenuation. ▶ Attenuation maps can be created using transmission scans (such as Germanium-68) or CT. ▶ Modern day PET/CT scanners use CT attenuation maps. ▶ Over-correction artifacts (“hot spots”) can occur at sites of metallic implants due to a discrepancy between

relative attenuation coefficients and the assumption in the attenuation map that bone is the highest density structure on CT. ▶ Distinguishing between an over-correction artifact and uptake related to inflammation/infection of a metallic implant can be done by reviewing the location of the uptake and the non-attenuation corrected images. Uptake related to inflammation or infection will typically be immediately adjacent to the implant and will still be visualized on the non-attenuation corrected image (see an example in Figure 130.3) while “hot spot” artifact will not.

Management ▶ Routine follow-up for the primary malignancy. Further Reading Blodgett TM, et al. PET/CT artifacts. Clin Imaging. 2011;35:49–63.

276

Part 9

General Oncologic Imaging Chun K. Kim, Katherine A. Zukotynski, Frederick D. Grant, Heather A. Jacene

Case 131 History ▶ None. 24 hours

Anterior

Inferior

Posterior

Superior

Figure 131.1 

279

Case 131  Carcinoid Tumor 24 hours

Transaxial

Anterior

Posterior

Figure 131.2 

Anterior

Coronal

Figure 131.3 

Radiopharmaceutical/Dose/Procedure: 111In-pentetreotide/5 mCi/somatostatin receptor imaging, 24 hours after injection, imaging at 4 hours optional, and delayed imaging at 48 hours as needed.

Findings (Figure 131.2) ▶ Intense 111In-pentetreotide uptake in the upper abdomen correlates to a necrotic mesenteric mass on contrast-enhanced CT (arrows).

▶ Intense focal activity in the liver correlates to an enhancing, partly hypodense lesion on contrast-enhanced

CT (arrowheads). A second site of intense activity medial and superior to this is seen in the liver on the planar posterior image.

Differential Diagnosis ▶ Well-differentiated neuroendocrine tumor with liver metastases ▶ Other somatostatin receptor positive tumors. Teaching Points ▶ 111In-pentetreotide is a radiolabeled eight amino-acid segment of somatostatin that binds to somatostatin receptors, mainly expressed on cells of neuroendocrine origin.

▶ 111In-pentetreotide imaging can be used to: ■ Localize neuroendocrine tumors with high diagnostic accuracy for most (80%–100%), except insulinomas and medullary thyroid cancer (sensitivity ~50%).

■ Predict response to octreotide therapy.

▶ Normal biodistribution (see also Case 133): kidneys, bladder, spleen, liver, thyroid, and gallbladder ■ Pituitary gland can also be seen. ■ Bowel activity not usually seen at 4 hours, but increases on delayed imaging. ▶ 111In-pentreotide uptake can be seen with chronic inflammation such as sarcoidosis, tuberculosis, and inflammatory bowel disease.

▶ SPECT and SPECT/CT are helpful for lesion localization and improve sensitivity of planar imaging for detection

of smaller lesions and lesions obscured by physiologic uptake in the kidneys, spleen, liver, and intestine. ■ Figure 131.3 (patient with Zollinger-Ellison syndrome and known liver metastases but no identifiable primary tumor): 111In-pentreotide scan showed focal activity in the pancreatic bed (arrowheads) in addition to multifocal activity in the liver (arrows). Gastrinoma in the body of pancreas was found at surgery. ▶ SPECT/CT may also increase specificity, e.g., gallbladder activity vs. tumor. ▶ Discontinuation of octreotide prior to performing an 111In-pentetreotide scan is needed to ensure accurate imaging detection of neoplastic disease.

Management ▶ Referral to medical oncology for further management. ▶ Consideration of somatostatin therapy for metastatic carcinoid. Further Reading Carrasquillo JA, Chen CC. Molecular imaging of neuroendocrine tumors. Semin Oncol. 2010 Dec;37(6):662–679.

280

Case 132 History ▶ A 16-year-old girl with headaches.

Figure 132.1 

281

Case 132 Pheochromocytoma

Figure 132.2 

Pt 1

MIBG

Renal scan

Pt 2

MIBG

Renal scan

Figure 132.3 

Radiopharmaceutical/Dose/Procedure: 123I-meta-iodobenzylguanine (123I-MIBG)/10 mCi/whole body imaging and SPECT at 24 hours.

Findings (Figure 131.2) ▶ Intense focal uptake in the left suprarenal region; physiologic MIBG uptake in liver and salivary glands;

excreted MIBG in the urinary bladder and bowel; mild focal activity in the upper abdomen (arrow) represents normal physiologic uptake in the right adrenal gland. ▶ MR shows a heterogenous T2 intense lesion in the expected location of the left adrenal gland that corresponds with the region of intense MIBG uptake on the co-registered SPECT/MR image.

Differential Diagnosis ▶ Adrenal pheochromocytoma: most likely ▶ Paravertebral paraganglioma or ganglioneuroma in the left retroperitoneum: much less likely. Teaching Points ▶ Pheochromocytoma is a sympathochromaffin tumor of the adrenal gland. ■ It can present with a classic triad of headaches, hypertension, and sweating, but also may be clinically obscure. ▶ The diagnosis of pheochromocytoma is confirmed by biochemical testing for elevated catecholamine levels in

urine and blood. ■ Imaging studies typically should not be performed before making a biochemical diagnosis. ▶ 123I-MIBG is a guanethidine analogue and taken up by sympathetic adrenergic tissue. ■ Highly accurate (> 90%) for identifying and localizing pheochromocytoma ■ Less sensitive for paraganglioma (an extra-adrenal sympathochromaffin tumor) ■ Rarely taken up by benign ganglioneuromas. ▶ Malignant pheochromocytoma is not a histological diagnosis, but is defined by the presence of metastases. ■ 123I-MIBG is 50%–70% sensitive for metastases. ■ In patients with suspected metastatic disease, if 123I-MIBG is negative, then consider 18F-FDG-PET/CT or 111In-pentetreotide scan. ▶ See Case 133 for discussion of normal distribution of MIBG. ■ Normal adrenal gland activity (arrow in Figure 132.2) or physiologic urine activity in the renal pelvis (Figure 132.3) can be confusing especially if unilateral. SPECT/CT or SPECT/MR co-registration can be helpful.

Management ▶ Surgical resection is the definitive treatment for pheochromocytoma. ▶ Standard chemotherapy is of little benefit for metastatic disease, but 131I-MIBG therapy may have promise for treating metastases.

Further Reading Bombardieri E, et al. 131I/123I-Metaiodobenzylguanidine (mIBG) scintigraphy: procedure guidelines for tumour imaging. Eur J Nucl Med Mol Imaging. 2010;37:2436–2446.

282

Case 133 History ▶ Below figures show six different patients’ studies performed using six different radiopharmaceuticals. Identify the radiopharmaceutical used in each study.

Figure 133.1 

Figure 133.4 

Figure 133.2 

Figure 133.5 

Figure 133.3 

Figure 133.6 

283

Case 133  Identify the Radiopharmaceutical Findings (Characteristic/Uncharacteristic of Each Radiopharmaceutical) ▶ Figure 133.1 (111In-pentetreotide): See also Case 131 ■ Spleen and kidneys—most intense; liver and gallbladder—moderately intense; bowel—variable; urinary bladder—variable depending on the amount of residual urine; thyroid—trace uptake may be seen.

■ Pituitary gland: Mild focal uptake occasionally may be seen, while pituitary uptake normally is not seen with other radiopharmaceuticals.

▶ Figure 133.2 (201Tl-chloride): ■ Myocardial uptake is always present; lungs and spleen may have a variable degree of mild diffuse uptake;

mild salivary gland activity; variable amounts of excreted activity can be seen in the bowel and urinary bladder. ▶ Figure 133.3 (123I-MIBG): See also Case 132 ■ Liver uptake typically is most intense; salivary gland uptake is always seen. ■ Myocardial uptake is typically, but not always, seen. ■ There is urinary excretion of tracer, which can be seen in the bladder activity and occasionally in the kidneys. Rarely, tracer accumulation in a dilated renal pelvis may be confused with an adrenal tumor on planar whole body images, and SPECT or SPECT/CT will be helpful. ▶ Figure 133.4 (111In-WBC): See also Cases 15–19 ■ Most intense uptake is in the spleen, followed by liver and bone marrow. ■ Unlike 111In-pentetreotide, renal uptake is not seen. ■ Any uptake other than in these three structures should be considered abnormal. ▶ Figure 133.5 (99mTc-HMPAO-WBC): See also cases in Part 2. ■ The relative distribution of tracer uptake in the liver, spleen, and bone marrow is similar to that of 111In-WBC. ■ In addition, mild diffuse pulmonary activity is almost invariably present, and excreted tracer is seen in the gastrointestinal and urinary tracts. ■ Image quality typically is superior to 111In-WBC because of the optimal photon energy of 99mTc and the higher administered activity. ▶ Figure 133.6 (67Ga-citrate): See also cases in Part 2. ■ Lacrimal activity is characteristic of 67Ga; it normally is not present with other radiopharmaceuticals. ■ 67Ga also localizes in the liver (usually most intense), bone/bone marrow, spleen, salivary glands, breast (especially if pregnant or lactating). Excreted tracer is seen in the colon. Kidneys may be seen faintly, but intense uptake after 24 hours is abnormal. ■ The relative intensity of uptake in organs/tissues can be highly variable among patients. ■ In this patient, multifocal uptake in the right neck is due to lymphoma. Prior to the introduction of FDG-PET, 67Ga was the primary radiopharmaceutical used for evaluation of lymphoma.

284

Case 134 History ▶ A 42-year-old woman with recently diagnosed left breast cancer.

Figure 134.1 

285

Case 134  Breast Lymphoscintigraphy

Figure 134.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sulfur colloid/1 mCi for same day surgery, 2 mCi for next-day surgery/Injection technique is variable (see Teaching Points). Dynamic and static imaging of the breast and ipsilateral axilla.

Findings (Figure 134.2) ▶ Injection site in the left breast (thick arrow) ▶ Multifocal uptake, representing sentinel lymph nodes, likely extending up to Level II/III. Differential Diagnosis ▶ None. Teaching Points ▶ Lymphoscintigraphy and sentinel lymph node (SLN) biopsy have changed the way surgeons stage malignant tumors. ▶ “SLN” concept ■ Assumption: There is orderly progression of tumor cells via the lymphatic system (unlike hematogenous spread). ■ Therefore, the first lymph node draining a tumor will be the first node to contain metastasis. ■ SLN biopsy is used to determine tumor involvement of a lymph node basin. ▶ Surgeons use a probe in the operating room to locate radioactive lymph nodes. Imaging may or may not be performed, depending on the surgeon’s preference.

▶ Positive impacts of SLN biopsy compared to axillary lymph node dissection: ■ Reduced surgical morbidity, trauma, and emotional stress by avoiding unnecessary lymph node dissection ■ Only a few lymph nodes undergo pathologic examination, which facilitates a more thorough examination of each node, and potentially leads to more accurate staging.

▶ Techniques to improve radiotracer activity in SLN: ■ Use filtered 99mTc-sulfur colloid because larger particles tend to remain at the injection site. ■ Subareolar and periareolar injections are reported to deliver more activity to axillary lymph nodes compared to intradermal or peritumoral injections.

▶ If imaging is performed, SLN location should be marked on overlying skin, based on anterior and lateral (or oblique) views. This skin marking can help the surgeon triangulate the location of the SN.

Management ▶ Patient undergoes SLN dissection in the OR. Further Readings Kim SC, et al. Using the intraoperative hand held probe without lymphoscintigraphy or using only dye correlates with higher sensory morbidity following sentinel lymph node biopsy in breast cancer: A review of the literature. World J Surg Oncol. 2005;3(1):64. Krynyckyi BR, et al. Areolar-cutaneous” junction” injections to augment sentinel node count activity. Clin Nucl Med. 2003;28 (2):97–107.

286

Case 135 History ▶ A 52-year-old man with recently diagnosed melanoma in the vertex of the head. Images of the head and neck region are shown in Figure 135.1.

Anterior

Posterior

Rt Lateral

Figure 135.1 

287

Case 135 Melanoma Lymphoscintigraphy/Sentinel Lymph Node (SLN) Mapping

Anterior

Posterior

Figure 135.2 

Rt Lateral

Figure 135.3 

Figure 135.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-sulfur colloid/1mCi divided into 2–4 equal fractions/2–4 intradermal injections around the lesion followed by planar imaging and SPECT/CT.

Findings ▶ Injection site in the vertex of the head ▶ Multiple right Level II/IIIB cervical lymph nodes (Figure 135.2; arrowheads). More nodes identified on SPECT/CT.

▶ Small focus seen on planar images (Figure 135.2; thin arrows) that was found to be a subcutaneous lymph

node in the mastoid region on SPECT/CT (not shown). Right lateral image shows a lymphatic track from the primary lesion to this small focus that is different from another track leading to more intense nodes. ▶ A small left Level IIB cervical lymph node between the left parotid gland and sternocleidomastoid muscle, seen only on SPECT/CT (Figure 135.3; arrows).

Differential Diagnosis ▶ None. Teaching Points ▶ See Teaching Points in Case 134. ▶ Unlike breast lymphoscintigraphy, the optimal field of view and imaging technique for melanoma

lymphoscintigraphy vary depending on the location of the primary lesion. When the lesion is located in: ■ Upper or lower extremity: Planar imaging over ipsilateral elbow/axilla or popliteal/inguinal region, respectively, is generally sufficient. ■ Head/upper neck: Planar imaging and, if available, SPECT/CT of the head and neck. Advantages of SPECT⁄CT in cervical SN mapping include: (1) identification of hot nodes missed on planar images, and (2) exact anatomical and 3-D localization of the SLN resulting in lower morbidity and reduced OR time. ■ Lower neck: Planar imaging and SPECT/CT of the neck, and planar imaging of the axillae. ■ Trunk: Both axillae and inguinal regions should be imaged as a SLN may be present on the contralateral side or in more than one region (Figure 135.4).

Management ▶ SLN mapping of three regions, i.e., subcutaneous region over the right mastoid, right Level II, left Level II between left parotid and sternocleidomastoid muscles.

Further Reading Klode J, et al. Advantages of preoperative hybrid SPECT/CT in detection of sentinel lymph nodes in cutaneous head and neck malignancies. J Eur Acad Dermatol Venereol. 2011;25(10):1213–1221.

288

Case 136 History ▶ A 36-year-old man with left lower extremity edema. Anterior

Posterior

Figure 136.1 

289

Case 136 Lymphedema Anterior

Posterior 20 min

Figure 136.2 

Figure 136.3 

40–60 min

4 hrs

>4 hrs

Figure 136.4 

Radiopharmaceutical/Dose/Procedure: 99mTc-sulfur colloid/2 mCi/Lower extremity lymphoscintigraphy.

Findings (Figure 136.2) ▶ In the right lower extremity, there is normal lymphatic drainage to inguinal and deep pelvic lymph nodes. ▶ In the left lower extremity, despite tracer accumulation in inguinal and pelvic lymph nodes, a dermal backflow pattern in the lower leg (arrow) indicates impaired lymphatic drainage.

▶ Normal uptake in the liver confirming patency of the lymphatic-venous system. ▶ Mild activity in the kidneys and bladder reflects excretion of a small amount of free technetium. Differential Diagnosis ▶ Lymphatic obstruction of the left lower extremity. Teaching Points ▶ Lymphoscintigraphy is indicated to discriminate lymphedema from leg swelling due to other causes such as chronic venous insufficiency or lipedema.

▶ Pathophysiology of lymphedema is early edema followed by chronic inflammation and fibrosis. ▶ For lower extremity lymphoscintigraphy, tracer is injected intradermally either in the web spaces between the toes or (preferably) in the dorsum of each foot.

▶ Patterns indicative of lymphedema include asymmetric uptake in inguinal/pelvic lymph nodes, dermal backflow pattern (see also Figure 136.3, arrows), and marked lymphatic collaterals.

▶ The most common lymphoscintigraphy finding in patients with lymphedema is delayed or absent uptake in

inguinal/pelvic lymph nodes. With normal lymphatic drainage, tracer accumulation should be seen within 45–60 minutes. In a patient with filariasis (Figure 136.4), inguinal/pelvic lymph nodes are not visualized until 4 hours.

Management ▶ Once lymphedema is confirmed, conservative measures, including compression, usually are adequate. Surgery is very rarely indicated.

Further Readings Greene AK, et al. Lower-extremity lymphedema and elevated body-mass index. N Engl J Med. 2012 May 31;366(22):2136–2137. Moshiri M, et al. Using lymphoscintigraphy to evaluate suspected lymphedema of the extremities. Am J Roentgenol. 2002;178(2):405–412. Ter S, et al. Lymphoscintigraphy: a reliable test for the diagnosis of lymphedema. Clin Nucl Med. 1993;18(8):646–654. Weissleder H, Weissleder R. Lymphedema: evaluation of qualitative and quantitative lymphoscintigraphy in 238 patients. Radiology. 1988:167:729–735.

290

Part 10

Thyroid and Parathyroid Frederick D. Grant, Chun K. Kim

Case 137 History ▶ A 22-year-old woman with hyperthyroidism. TSH < 0.004 mU/L (normal 0.5–5.0), T4 20.4 mcg/dL .

(normal 6–12).

ANTERIOR

LAO

RAO

BIRDS-EYE

Figure 137.1 

Radioactive iodine uptake: 64% at 4 hours (reference range 5%–15%) 76% at 24 hours (reference range 10%–30%).

293

Case 137  Hyperthyroidism, Graves Disease

ANTERIOR

LAO

RAO

BIRDS-EYE

Figure 137.2 

Radiopharmaceutical/Dose/Procedure ▶ 123I-sodium iodide/0.3–0.4 mCi/thyroid scan, pinhole imaging 4–6 hours after oral administration, radioactive iodine uptake (RAIU) measured 4–24 hours after administration

▶ An alternative, but less desirable, approach is to perform thyroid imaging 15–30 minutes after intravenous

administration of 5–10 mCi 99mTc-pertechnetate and then determine RAIU using 131I-sodium iodide (7–10 microcuries, oral).

Findings ▶ Enlarged, fairly symmetric thyroid gland with a prominent pyramidal lobe ▶ Diffuse or mildly patchy uptake pattern ▶ Increased RAIU ▶ These findings in a patient with a suppressed serum TSH level are diagnostic of Graves disease. Differential Diagnosis of Hyperthyroidism ▶ Graves disease ▶ Subacute thyroiditis ▶ Hashimoto’s thyroiditis ▶ Hyperfunctioning thyroid nodule ▶ Excess exogenous thyroid hormone ▶ Secondary hyperthyroidism (TSH-secreting pituitary tumor, hCG-secreting trophoblastic tumor). Teaching Points ▶ Typical symptoms of hyperthyroidism include palpitations, heat intolerance, weight loss, and sleep disturbance; most patients with Graves disease will have a goiter (enlarged thyroid gland).

▶ Graves disease is the most common cause of thyrotoxicosis and is more common in females than males (5:1). ▶ In Graves disease, autonomous thyroid function is mediated by an autoantibody to the TSH receptor that stimulates thyroid function

▶ Patients with primary hyperthyroidism, including Graves disease, will have a suppressed TSH level. ▶ Increased or normal RAIU in the absence of TSH (suppressed TSH) indicates TSH-independent thyroid function. ▶ In primary hyperthyroidism, diffusely increased uptake (with an elevated RAIU) almost always is diagnostic of Graves disease. However, a normal RAIU, in the absence of TSH, does not exclude Graves disease.

Management ▶ Medical therapy (propylthiouracil, methimazole) ▶ Radioactive iodine therapy (cannot be used in pregnancy) ▶ Surgery (thyroidectomy) is rarely used, except when medical therapy and radioiodine cannot be used. Further Readings Brent GA. Clinical practice: Graves’ disease. N Engl J Med. 2008;358:2594–2605. Franklyn JA, Boelaert K. Thyrotoxicosis. Lancet. 2012;379:1155–1116. Ross DS. Radioiodine therapy for hyperthyroidism. N Engl J Med. 2011;364:542–550.

294

Case 138 History ▶ A 58-year-old woman with chest and neck pain, dyspnea, and hot flashes. TSH 0.02 mU/L (normal 0.3–5.0), total T4 13.4 mcg/dL (normal 5–11). Radioactive iodine uptake: 4% at 4 hours (reference range 5%–15%), 2% at 24 hours (reference range 10%–30%).

Figure 138.1 

295

Case 138  Hyperthyroidism, Subacute Thyroiditis

Figure 138.2  Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (oral)/15 MBq (0.4 mCi)/thyroid scan and uptake.

Findings ▶ Minimal radioactive iodine uptake (RAIU) in the thyroid gland. Differential Diagnosis of Minimal Iodine Uptake in the Thyroid Gland ▶ In a patient with biochemical/clinical hyperthyroidism ■ Subacute thyroiditis ■ Exogenous thyroid hormone intake ■ Ectopic thyroid hormone production ▶ After excess intake of iodine ■ Dietary/health supplements (e.g., kelp) ■ Medications (e.g., amiodarone, iodinated anti-tussives) ■ Iodinated CT or angiography contrast ▶ In a patient with hypothyroidism ■ Chronic thyroiditis ■ Prior thyroid ablation or thyroidectomy. Teaching Points ▶ Subacute thyroiditis is the most likely diagnosis in this patient with hyperthyroidism and minimal RAIU. ■ Exogenous thyroid hormone intake must be excluded by clinical history. ■ Ectopic thyroid hormone production could have a similar appearance, but is exceedingly rare. ▶ Subacute thyroiditis represents autoimmune destruction of the thyroid. It can occur after a viral illness, can occur postpartum, or can be idiopathic.

▶ There are three typical phases of subacute thyroiditis. ■ Hyperthyroid: Unregulated release of stored thyroid hormone (T4, T3) suppresses TSH levels ■ Hypothyroid: Little thyroid hormone secretion, TSH levels begin to increase ■ Recovery: Thyroid hormone secretion resumes under control of TSH. ▶ Only one or two of the phases may be clinically apparent; in the absence of the recovery phase, the patient remains hypothyroid.

Management ▶ Treatment is symptomatic. NSAIDs may be helpful if the thyroid is painful. ▶ Neither antithyroid medication nor radioactive iodine therapy is effective, and should not be used. Further Reading Sarkar SD. Benign thyroid disease: what is the role of nuclear medicine? Semin Nuc Med. 2006;36:185–193.

296

Case 139 History ▶ A 74-year-old man with palpitations; he recently changed blood pressure medication and is

recovering from a recent viral illness. TSH 0.004 mU/L (reference range 0.5–5.0), T4 14.4 mcg/dL (reference range 5–11).

Figure 139.1  Radioiodine uptake at 4 hours = 15% (reference range 5%–15%).

297

Case 139  Hyperthyroidism, Graves Disease

Figure 139.2  Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (oral)/15 MBq (0.4 mCi)/thyroid scan and uptake at 4 hours.

Findings ▶ Patchy uptake throughout the thyroid gland, RAIU near the upper limit of normal in the absence of TSH (suppressed TSH).

Differential Diagnosis ▶ Graves disease ▶ Normal thyroid ▶ Recovery phase of subacute thyroiditis. Teaching Points ▶ Non-focal RAIU near the upper limit of normal in the absence of TSH indicates TSH-independent or autonomous thyroid function. This almost always represents Graves disease.

▶ In Graves disease, the TSH receptor is stimulated by an activating autoantibody directed against the TSH

receptor. The RAIU typically is elevated above the reference range, but occasionally may be within the reference range. ▶ This is not a normal thyroid gland, as the patient has laboratory evidence of hyperthyroidism. ▶ This is not recovery from subacute thyroiditis, despite the history of viral illness. With subacute thyroiditis, RAIU does not recover until the TSH returns to the normal range. ▶ This patient likely had long-standing mild Graves disease with symptoms attenuated by propanolol, used to treat hypertension. After propanolol was discontinued, the patient noted palpitations. ▶ This case demonstrates that not all cases of Graves disease are severe or even clinically obvious.

Management ▶ Medical therapy (propylthiouracil, methimazole) ▶ Radioactive iodine therapy (cannot be used in pregnancy) ▶ Surgery (thyroidectomy); rarely used, except when medical therapy and radioiodine cannot be used. Further Readings Sarkar SD. Benign thyroid disease: what is the role of nuclear medicine? Semin Nuc Med. 2006;36:185–193. Cooper DS. Approach to the patient with subclinical hyperthyroidism. J Clin Endocrinol Metab. 2007;92:3–9.

298

Case 140 History ▶ A 44-year-old woman with a palpable thyroid nodule. T4 11.4 mcg/dL (reference 6–12), TSH 0.1 mU/L (0.5–5.0).

Figure 140.1  Radioactive iodine uptake: 27% at 24 hours (reference range 10%–30%)

299

Case 140  Autonomous (“Hot”) Thyroid Nodule

Figure 140.2  Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (oral)/15 MBq (0.4 mCi)/thyroid scan at 4 hours and uptake at 24 hours.

Findings ▶ Intense uptake in the inferior pole of the left lobe of the thyroid gland corresponds to the palpable nodule ▶ Minimal uptake in the rest of the thyroid gland. Differential Diagnosis ▶ Autonomous (“hot”) thyroid nodule (also known as a toxic adenoma) ▶ Multinodular goiter with a single toxic adenoma. Teaching Points ▶ An autonomous (“hot”) thyroid nodule secretes sufficient thyroid hormone to suppress TSH levels, and thus suppresses function of normal thyroid tissue.

▶ The hyperthyroidism may be subclinical (suppressing TSH without overt symptoms) or clinically apparent. ▶ Thyroid scan may be the first test of choice to evaluate a thyroid nodule only when TSH suppression suggests that the nodule may be “hot.”

▶ RAIU for the whole thyroid typically is in the normal range or only mildly elevated. ▶ Hot thyroid nodules are very rarely malignant, and the clinical goal is to treat the hyperthyroidism. Management ▶ Antithyroid medications are less effective for autonomous thyroid nodules than for Graves disease. ▶ Surgical resection of the nodule is an effective therapy. ▶ Radioactive iodine (I-131) will be taken up by the hot nodule; there is little uptake in the suppressed normal thyroid gland, so that normal thyroid is preserved after radioiodine therapy.

▶ After surgical or radionuclide ablation of the overactive nodule, TSH will no longer be suppressed, and the rest of the thyroid should resume normal function.

Further Readings Cooper DS, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009;19:1167–1214. Gharib H, et al. American Association of Clinical Endocrinologists, Associazione Medici Endocrinologi, and European Thyroid Association medical guidelines for clinical practice for the diagnosis and management of thyroid nodules. Endocr Pract. 2010;16:S1–S43.

300

Case 141 History ▶ A 52-year-old woman with elevated T4 and suppressed TSH; ultrasonography shows a multinodular goiter.

RAO

Anterior

LAO

Figure 141.1 

301

Case 141  Graves Disease Versus Toxic Nodular Disease

RAO

Anterior

Figure 141.2 

RAO

LAO

Figure 141.3 

Anterior

LAO

RAO

Anterior

LAO

Figure 141.4 

Radiopharmaceutical/Dose/Procedure: Figures 141.2 and 141.4: 99mTc-pertechnetate/5–10 mCi intravenously/ thyroid scan at 15–30 minutes; Figure 141.3: 123I-sodium iodide/0.4 mCi oral/thyroid scan at 4 hours.

Findings ▶ Figure 141.2 (99mTc-pertechnetate): Diffusedly increased uptake with several cold defects; preserved outline of the thyroid; prominent pyramidal lobe

▶ Figure 141.3 (123I): Multiple regions of increased and decreased uptake in both thyroid lobes; mildly irregular outline of the thyroid

▶ Figure 141.4 (99mTc-pertechnetate): 2 large and 3 small (arrows) foci of increased uptake; no uptake in the rest of the thyroid gland.

Differential Diagnosis ▶ Toxic multinodular goiter: multiple hyperfunctioning nodules ▶ Graves disease with multiple cold nodules ▶ Graves disease with concurrent hyperfunctioning nodules (Marine Lenhart syndrome). Teaching Points ▶ See also Cases 137–140. ▶ In a hyperthyroid patient with thyroid nodules, the distinction between Graves disease and toxic nodular disease can be challenging.

▶ Findings favoring Graves disease: ■ Clinical findings: Graves ophthalmopathy, elevated TSH-receptor antibodies ■ Markedly elevated RAIU ■ Preservation of the outline of the thyroid (Figures 141.2, 141.3). ■ Visualization of the pyramidal lobe (Figure 141.2) ▶ Findings favoring toxic nodular disease: ■ Focal nodular uptake with suppression of remaining thyroid tissue (Figure 141.4 and Case 140) ▶ Findings favoring Graves disease with concurrent autonomous hyperfunctioning nodules (Marine Lenhart syndrome): ■ Homogeneous or patchy uptake throughout the entire thyroid, including nodules.

Management ▶ Radioiodine (131I) treatment may treat hyperthyroidism caused by either Graves disease or toxic multinodulalar goiter.

▶ Surgical excision may be treatment of choice for cosmetic reasons or if there are concurrent nonfunctional (“cold”) nodules.

▶ A nonfunctional thyroid nodule that remains or develops after radioiodine treatment of Graves disease must be evaluated for possible malignancy.

Further Readings Carnell NE, Valente WA. Thyroid nodules in Graves’ disease: classification, characterization, and response to treatment. Thyroid. 1998;8:571–576. Pazaitou-Panayiotou K, et al. Thyriod cancer in patients with hyperthyroidism. Horm Metab Res. 2012;44:255–262.

302

Case 142 History ▶ A 65-year-old woman with a palpable thyroid nodule in the right lobe of the thyroid gland. T4 9.6 mcg/dL (reference 6–12), TSH 1.1 mU/L (0.5–5.0) (Figure 142.1).

Figure 142.1 

History A 15-year-old girl with palpable thyroid nodule in the left lobe of the thyroid gland (Figure 142.2).

ANTERIOR

LAO

RAO

Figure 142.2 

303

Case 142  Nonfunctional (“Cold”) Thyroid Nodule

ANTERIOR

Figure 142.3 

LAO

RAO

Figure 142.4 

Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (oral)/15 MBq (0.4 mCi)/thyroid scan at 4 hours.

Findings ▶ Photopenic defects in the lateral aspect of the right lobe of the thyroid gland (Figure 142.3) and lateral aspect

of the lower left lobe of the thyroid gland (Figure 142.4) are consistent with hypofunctioning (“cold”) nodules.

▶ Function in the normal regions of the thyroid glands is not affected. Differential Diagnosis ▶ Benign thyroid cyst ▶ Benign thyroid adenoma ▶ Thyroid carcinoma ▶ Medullary thyroid carcinoma ▶ Parathyroid adenoma ▶ Metastasis from an extrathyroidal malignancy.

Teaching Points ▶ Thyroid carcinoma accounts for only 5%–8% of nonfunctional thyroid nodules, but drives the need to fully evaluate all thyroid nodules.

▶ A thyroid scan also can be performed 15–30 minutes after oral administration of 99mTc-pertechnetate.

However, occasionally, a nodule that shows uptake on a pertechnetate scan would be cold on an 123I thyroid scan. This has been called a “discordant nodule,” and malignancy cannot be excluded.

Management ▶ Ultrasound can characterize nodules as solid, simple cyst, or complex cyst; simple cysts are unlikely to be malignant.

▶ Fine needle aspiration, typically under ultrasound guidance, can provide a histopathology in 90% of cases. ▶ The use of thyroid scan to evaluate thyroid nodules should be limited to cases in which there is clinical suspicion of an autonomous (“hot”) nodule, as suggested by a suppressed TSH.

Further Readings Cooper DS, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009;19:1167–1214. Gharib H, et al. American Association of Clinical Endocrinologists, Associazione Medici Endocrinologi, and European Thyroid Association medical guidelines for clinical practice for the diagnosis and management of thyroid nodules. Endocr Pract. 2010;16:S1–S43.

304

Case 143 History ▶ A 3-week-old girl with hypothyroidism diagnosed on postnatal screening. Thyroid hormone replacement therapy was started 1 week ago.

ANTERIOR

LATERAL

Figure 143.1  Radioiodine uptake is 7% at 4 hours and 4% at 24 hours.

305

Case 143  Neonatal Hypothyroidism With an Ectopic Thyroid Gland

ANTERIOR

LATERAL

Figure 143.2  Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (oral)/0.2 mCi/Thyroid scan.

Findings ▶ There is no radioiodine uptake in the expected location of the thyroid in the neck. ▶ Focal uptake at the base of the tongue is best localized on the lateral image. Differential Diagnosis of Neonatal Hypothyroidism ▶ Thyroid agenesis ▶ Ectopic thyroid gland ▶ Maternal blocking antibodies (anti-TSH receptor) ▶ Dyshormonogenesis. Teaching Points ▶ Congenital hypothyroidism has an incidence of 2 per 100,000 in North America. Most cases are diagnosed on postnatal screening, which is nearly universal in North America.

▶ Early and continuous thyroid hormone replacement therapy is essential to prevent neurodevelopmental delay. Thyroid hormone replacement should not be delayed (or discontinued) to perform the diagnostic imaging.

▶ A wide field of view may be needed to localize functioning ectopic thyroid tissue. ▶ Rapid washout of radioactive iodine from the thyroid may suggest impaired iodine organification, which can produce a defect in thyroid hormone synthesis.

Management ▶ Therapy (thyroid hormone replacement therapy) is not delayed while performing diagnostic studies. ▶ Once ectopic thyroid tissue has been localized, thyroid structure can be evaluated further with ultrasound. ▶ Follow-up evaluation can be performed after age 3, when thyroid hormone replacement therapy can be discontinued temporarily without causing adverse neurodevelopmental effects.

Further Readings DeSilva A, et al. The role of scintigraphy and ultrasound in the imaging of neonatal hypothyroidism: 5-year retrospective review of single-centre experience. J Med Imaging Radiat Oncol. 2014;58:420–430. Schoen EJ, et al. The key role of newborn thyroid scintigraphy with isotopic iodide (123I) in defining and managing congenital hypothyroidism. Pediatrics. 2004;114:e683–688.

306

Case 144 History ▶ A 45-year-old woman with differentiated thyroid carcinoma, 3 months status post-thyroidectomy. A whole body radioiodine scan is shown in Figure 144.1. ■ Is this an 123I-NaI scan or 131I-NaI scan? Why? ■ Does this patient have metastatic disease?

Figure 144.1 

307

Case 144 Thyroid Hormone Metabolism in the Liver/Radioiodine Uptake in Tooth Filling

Figure 144.2 

Figure 144.3 

Radiopharmaceutical/Dose/Procedure: 131I-NaI/30 mCi (ablation dose)/Post-therapy whole body imaging 6 days after oral administration.

Findings ▶ Figure 144.2: ■ Finding 1: Intense focus in the right neck ■ Finding 2: Two foci of activity in the oral region ■ Finding 3: Diffuse liver activity. ▶ Figure 144.3: Two foci of tracer activity correspond to dental metals. Differential Diagnosis (Based on Figure 144.2 Alone) ▶ Finding 1: Thyroid remnant vs. metastatic right cervical lymph node. SPECT/CT confirmed the former (not shown). ▶ Finding 2: Normal variant vs. upper cervical lymph nodes. SPECT/CT (Figure 144.3) excluded the latter. ▶ Finding 3: Physiological vs. diffuse liver metastasis. Teaching Points ▶ As thyroid hormone is metabolized in the liver, radioiodine scan may show liver activity when functioning

thyroid tissue (either remnant or metastatic tumor) is present. ■ Therefore, the post-ablation scan after the first therapy (performed after thyroidectomy to ablate thyroid remnant) often shows liver activity. ■ However, liver activity in the absence of thyroid remnant in the neck (typically on follow-up studies) indicates occult metastases, either too small or dedifferentiated (see Figure 146.4 in Case 146). ■ Since it generally takes several days from the time iodide is trapped by thyroid/tumor tissue until it ends up in the liver, this finding is observed neither on 131I scan obtained within 2–3 days nor on 123I scan that is generally performed at 24 hours after tracer administration. ▶ Although diffuse oral activity almost invariable represents physiologic activity, e.g., saliva, focal activity may be confusing (e.g., upper cervical lymph node?). A recent study showed partially reversible binding of radioiodine to common dental metals.

Management ▶ Thyroid hormone replacement therapy ▶ Follow-up in 6–12 months. Further Readings Burlison JS et al. SPECT/CT localization of oral radioiodine activity: a retrospective study and in-vitro assessment. Nucl Med Commun. 2013;34:1216–1222. Chung JK, et al. Clinical significance of hepatic visualization on iodine-131 whole-body scan in patients with thyroid carcinoma. J Nucl Med. 1997;38:1191–1195.

308

Case 145 History ▶ A 21 year-old female with thyroid cancer, near-total thyroidectomy performed 3 months ago.

May 9

May 1

Figure 145.1 

Figure 145.2 

309

Case 145 Pre-Treatment 123I Scan and Post-Therapy 131I Scan in a Patient With Thyroid Cancer Radiopharmaceutical/Dose/Procedure ▶ Figure 145.1: Pre-treatment 123I scan at 24 hours after oral administration of 123I (3 mCi) ▶ Figure 145.2: 131I (75 mCi) therapy on May 2 followed by post-therapy 131I scan at 7 days. Findings ▶ Pre-treatment: ■ 3 foci of intense 123I uptake in the thyroid bed ■ Expected physiologic uptake in salivary glands, breasts, gastric mucosa ■ Excreted 123I in nasal/oral secretions, gastrointestinal and urinary tracts. ▶ Post-therapy: ■ Numerous foci of 131I uptake in the anterior neck and upper chest ■ Physiologic hepatic activity ■ Excreted 131I in the gastrointestinal tract; pelvic accumulation is in the rectum, not the bladder ■ “Star artifact,” most notable over the pelvis, reflects collimator septal penetration by 131I high-energy gamma emission.

Differential Diagnosis ▶ Remnant thyroid tissue ▶ Iodine-avid metastases, more apparent on the post-therapy scan. Teaching Points ▶ Pre-therapy scans typically use 123I; even moderate 131I doses may “stun” thyroid tissue, which might decrease the effectiveness of subsequent 131I therapy. ▶ 131I (half-life 8 days) can be imaged at 7 days, while 123I (half-life 13 hours) cannot. ▶ Physiologic uptake pattern changes between 1 and 7 days: ■ Decreased salivary and gastric uptake reflects iodine washout. ■ Increased liver uptake reflects hepatic metabolism of radioiodinated thyroid hormone produced by functional remnant thyroid or metastases. ▶ In approximately 10% of cases, disease seen on the 131I post-therapy scan is not identified on the pre-therapy 123I scan. This increased sensitivity is despite poorer 131I image quality and reflects: ■ Higher administered activity of 131I ■ Improved radioiodine biodistribution at 7 days.

Management ▶ Pre-therapy scan with 3–5 mCi 123I can guide management, including 131I therapy ▶ Post-therapy 131I scan may identify additional sites of metastases, which can guide future follow-up and management.

Further Readings Chung JK, et al. Clinical significance of hepatic visualization on iodine-131 whole-body scan in patients with thyroid carcinoma. J Nucl Med. 1997;38:1191–1195. Reiners C, et al. Radioiodine for remnant ablation and therapy of metastatic disease. Nat Rev Endocrinol. 2011;7:589–595.

310

Case 146 History ▶ An 18-year-old female with metastatic papillary thyroid cancer referred after thyroidectomy and radioiodine thyroid ablation.

Figure 146.1: Whole body imaging 7 days after 7,400 MBq (200 mCi) 131I-sodium iodide. Figure 146.2: One year later, whole body imaging 7 days after a second therapy with 12,000 MBq (325 mCi) 131I.

Figure 146.1 

Figure 146.2 

311

Case 146 Papillary Thyroid Cancer; Progressive Lung Metastases with Decreasing Iodine Avidity

Figure 146.3 

Figure 146.4 

Radiopharmaceutical/Dose/Procedure: See History, 18F-Fluoro-deoxyglucose/12 mCi/PET-CT

Findings ▶ Figure 146.1: Intense lung uptake reflects widespread pulmonary metastases seen on a chest radiograph. ▶ Figure 146.2: Marked interval decrease in 131I uptake, despite progressive disease on chest radiograph. Focal

uptake in the neck likely represents recurrent disease. Focal uptake in the left upper quadrant represents radioiodine residual on the intragastric portion of a percutaneous gastric feeding tube. ▶ Figure 146.3. 18F-FDG PET/CT confirms extensive FDG-avid bilateral pulmonary and pleural disease and right pleural effusion. The whole body MIP image (right panel) of the FDG-PET shows physiological uptake in the vocal cords, but no FDG-uptake in 131I-avid recurrent disease in the neck.

Differential Diagnosis (Based on Two Post-Therapy 131I Scans) ▶ Disease progression with loss of iodine avidity ▶ Disease response to therapy ▶ Pulmonary fibrosis related to therapy with residual iodine-avid disease. Teaching Points ▶ Whole body imaging is performed typically 5–10 days after administration of therapeutic radioiodine. ▶ Decreased radioiodine uptake in metastatic disease usually indicates a response to prior radioiodine

therapy, but with progressive disease on chest radiograph or CT more likely reflects loss of iodine avidity by dedifferentiated tumor cells. ▶ Loss of iodine avidity may be asynchronous; some metastases show loss of iodine uptake and others show persistent iodine avidity. ▶ Loss of iodine avidity typically correlates with increased FDG-avidity. Figure 146.4 is another case illustration of a negative post-131I-therapy scan (left panel) despite the presence of numerous FDG-avid metastases (right panel). ▶ Radiation-induced pulmonary fibrosis could have a similar appearance, but is unlikely before administration of multiple high doses of 131I.

Management ▶ 131I is the specific therapy for metastatic differentiated thyroid cancer. There are many approaches to determining the dose and frequency of 131I.

▶ Loss of radioiodine avidity diminishes the response to therapeutic I-131. Therapy options include surgical excision, investigational chemotherapy, or empiric radioiodine as a palliative therapy.

Further Readings Reiners C, et al. Radioiodine for remnant ablation and therapy of metastatic disease. Nat Rev Endocrinol. 2011;7:589–595. Wong KK, et al. Hybrid SPECT-CT and PET-CT imaging of differentiated thyroid carcinoma. Br J Radiol. 2009;82:860–876.

312

Case 147 History ▶ A 55-year-old woman with fatigue. Lab: calcium 11.1 mg/dL (reference range 8.0–10.2), PTH 65 mg/dL (reference range 5–60). 20 min

120 min

Figure 147.1 

313

Case 147 Parathyroid Adenoma: Single-Isotope Dual-Phase Technique 20 min

120 min

Figure 147.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sestamibi/20 mCi/Planar imaging, both at 20 and 120 minutes.

Findings ▶ Planar images of the neck at 20 minutes show uptake throughout both lobes of the thyroid gland. ▶ After 120 minutes, planar images of the neck show washout of tracer from the thyroid leaving focal uptake near the inferior pole of the right thyroid lobe, identified as a parathyroid adenoma at surgery.

▶ Persistent tracer accumulation in the myocardium (and to a lesser extent in skeletal muscle) also is typical of 99mTc-sestamibi.

Differential Diagnosis ▶ Parathyroid adenoma ▶ Parathyroid carcinoma ▶ Thyroid adenoma ▶ Hyperplastic lymph node. Teaching Points ▶ Primary hyperparathyroidism is characterized by hypercalcemia and elevated PTH level. ▶ Complications of hyperparathyroidism include bone disease (osteomalacia, brown tumors), renal calculi, psychiatric symptoms (depression), constipation, and fatigue.

▶ A single parathyroid adenoma is the most common cause (> 80%) of primary hyperparathyroidism. ▶ Nuclear medicine preoperative localization of a parathyroid adenoma can guide the surgical approach and facilitate limited neck exploration.

▶ Parathyroid scan is less sensitive for identifying parathyroid hyperplasia. Management ▶ Imaging is not necessary for the diagnosis of hyperparathyroidism, but preoperative localization of a parathyroid adenoma can guide the surgical approach and limit surgical exploration of the neck.

▶ Successful surgical parathyroidectomy is curative for parathyroid adenoma and is most appropriate in patients with severe or symptomatic hypercalcemia.

▶ Observation and follow-up might be appropriate in younger patients, patients with mild or asymptomatic hypercalcemia, and patients with higher surgical risk.

▶ Calcimimetics act on parathyroid calcium receptors to suppress parathyroid gland secretion and provide a newly available medical option for the treatment of hyperparathyroidism.

Further Readings Chien D, et al. Imaging of parathyroid glands. Otolaryngol Clin North Am. 2010;43:399–415. Greenspan BS, et al. SNM practice guideline for parathyroid scintigraphy 4.0. J Nucl Med Technol. 2012; 40:111–118. Judson BL, et al. Nuclear imaging and minimally invasive surgery in the management of hyperparathyroidism. J Nucl Med. 2008;49:1813–1818.

314

Case 148 History ▶ A 62-year-old woman with fatigue and depression. Lab: calcium 11.4 mg/dl (reference 8.0–10.2), PTH 82 mg/dl (reference 5–60).

Figure 148.1 

315

Case 148  Parathyroid Adenoma: Dual-Isotope Technique

Figure 148.2  Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide (0.4 mCi) and pinhole imaging 4 hours after oral administration, immediately followed by intravenous injection of 99mTc-sestamibi (20 mCi) and pinhole imaging at 20 and 120 minutes.

Findings ▶ Persistent focus of increased 99mTc-sestamibi uptake near the lower pole of the right lobe of the thyroid is not present on the 123I image (mismatched).

Differential Diagnosis ▶ Parathyroid adenoma ▶ Parathyroid carcinoma ▶ Thyroid adenoma ▶ Hyperplastic lymph node, less likely. Teaching Points ▶ A single parathyroid adenoma is the most common cause (> 80%) of primary hyperparathyroidism. ▶ Nuclear medicine may utilize either a single-isotope, dual-phase technique with 99mTc-sestamibi or a dual-isotope subtraction technique. The two techniques can be complementary.

▶ With the dual isotope technique, 123I or 99mTc-pertechnetate is taken up only by the thyroid, but not by the parathyroid. Therefore, these images are visually compared with or electronically subtracted from images acquired with 99mTc-sestamibi.

Management ▶ Preoperative localization of a parathyroid adenoma can guide the surgical approach and limit surgical exploration of the neck.

▶ Successful surgical parathyroidectomy is curative for parathyroid adenoma and is most appropriate in patients with severe or symptomatic hypercalcemia.

▶ Observation and follow-up might be appropriate in younger patients, patients with mild or asymptomatic hypercalcemia, and patients with higher surgical risk.

▶ Calcimimetics act on parathyroid calcium receptors to suppress parathyroid gland secretion and provide a newly available medical option for the treatment of hyperparathyroidism.

Further Readings Chien D, et al. Imaging of parathyroid glands. Otolaryngol Clin North Am. 2010;43:399–415. Kim CK et al. The efficacy of sestamibi parathyroid scintigraphy for directing surgical approaches based on modified interpretation criteria. Clin Nucl Med. 2002;27:246–248. Palestro CJ, et al. Radionuclide imaging of the parathyroid glands. Semin Nucl Med. 2005;35:266–276.

316

Case 149 History ▶ A 16-year-old boy with hip pain and hypercalcemia.

20 min

120 min

Figure 149.1 

317

Case 149  Parathyroid Carcinoma

20 min

120 min

Figure 149.2  Radiopharmaceutical/Dose/Procedure:

Figure 149.3  99mTc-sestamibi/10

mCi/Pinhole imaging at 20 and 120 minutes.

Findings ▶ Figure 149.2: Parallel-hole (top row) and pinhole (bottom row) images of the neck at 20 minutes show uptake

throughout both lobes of the thyroid gland with a large ovoid region of more prominent activity in the region of the right lobe of the thyroid. After 120 minutes, there has been rapid washout of tracer from most of the thyroid, but not from an ovoid region near or in the right lobe of the thyroid gland ▶ Figure 149.3: Pelvis CT shows thinned cortex of the right ilium with adjacent hypodense mass (white arrow), compatible with osteitis fibrosa cystica, an unusual manifestation of long-standing hyperparathyroidism. With bone windows, the CT shows widening of the sacroiliac joints (black arrow) due to subperiosteal resorption, which is a typical manifestation of chronic hyperparathyroidism.

Differential Diagnosis ▶ Parathyroid adenoma ▶ Parathyroid carcinoma ▶ Thyroid adenoma. Teaching Points ▶ Parathyroid carcinoma accounts for fewer than 5% of cases of primary hyperparathyroidism. ▶ Imaging characteristics rarely distinguish parathyroid adenoma from parathyroid carcinoma. ▶ The diagnosis of parathyroid carcinoma typically is made upon the resection of a presumed adenoma. ▶ Osteitis fibrosa cystica (brown tumor) is a lytic lesion resulting from osteoclast stimulation by long-standing primary PTH excess and is rare in the modern era.

Management ▶ Surgical resection is the primary therapy for parathyroid carcinoma. ▶ Calcimimetics act on parathyroid calcium receptors to suppress parathyroid gland secretion and may help to control PTH levels in patients with remnant or inoperable parathyroid cancer.

Further Readings Chien D, et al. Imaging of parathyroid glands. Otolaryngol Clin North Am. 2010;43:399–415. Fang SH, et al. Parathyroid cancer. Endocr Pract. 2011;17:S36–S41. Hong WS, et al. Emphasis on the MR imaging findings of brown tumor: a report of five cases. Skeletal Radiol. 2011;40:205–213.

318

Case 150 History ▶ A 29-year-old man with chronic renal failure.

20 min

120 min

20 min

120 min

Figure 150.1 

319

Case 150 Secondary Hyperparathyroidism, Parathyroid Hyperplasia

20 min

120 min

20 min

120 min

Figure 150.2  Radiopharmaceutical/Dose/Procedure: 99mTc-sestamibi/20 mCi/Parallel hole (top row) and pinhole imaging (bottom row), both at 20 (Figure 150.2; A) and 120 minutes (B); 123I sodium iodide/0.4 mCi/pinhole image at 4 hours (C).

Findings ▶ Images of the neck at 20 minutes show multiple sites of uptake in the expected location of the thyroid gland.

After 120 minutes, the images show washout of tracer from some sites, leaving four foci of increased uptake.

▶ Pinhole 123I thyroid image (Figure 150.2C) demonstrates the conformation of the thyroid gland. Comparison

with the sestamibi images shows expected washout of 99mTc-sestamibi from the thyroid, with persistent uptake in four hyperplastic parathyroid glands.

Differential Diagnosis ▶ Primary hyperparathyroidism due to four-gland hyperplasia ▶ Secondary hyperparathyroidism resulting in four-gland hyperplasia. Teaching Points ▶ 99mTc-sestamibi is most accurate for localizing a parathyroid adenoma, and only approximately 50% sensitive for parathyroid hyperplasia. A negative 99mTc-sestamibi scan does not exclude parathyroid hyperplasia. ▶ Hyperplasia of all four parathyroid glands usually occurs with secondary hyperparathyroidism, such as in patients with chronic renal failure. ▶ Primary hyperparathyroid hyperplasia commonly is associated with an endocrine genetic syndrome, such as multiple endocrine neoplasia (MEN-1).

Management ▶ Secondary hyperparathyroidism is best managed by treating the underlying condition (e.g., renal transplant) or rigorous replacement of vitamin D to prevent hypocalcemia (and thus avoid PTH stimulation).

▶ Surgical parathyroidectomy may be necessary; in order to avoid hypoparathyroidism, the surgeon may leave a fragment of one parathyroid gland in the neck.

▶ Calcimimetics act on parathyroid calcium receptors to suppress parathyroid gland secretion and provide a newly available medical option for treatment of secondary hyperparathyroidism.

Further Readings Chien D, et al. Imaging of parathyroid glands. Otolaryngol Clin North Am. 2010;43:399–415. Greenspan BS, et al. SNM practice guideline for parathyroid scintigraphy 4.0. J Nucl Med Technol. 2012; 40:111–118. Palestro CJ, et al. Radionuclide imaging of the parathyroid glands. Semin Nucl Med. 2005;35:266–276.

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Case 151 History ▶ A 48-year-old woman with hypercalcemia. Calcium 12.3 mg/dl (reference 8.0–10.2), PTH 230 mg/dl (reference 5–60).

15 minutes

120 minutes

Figure 151.1 

Figure 151.2 

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Case 151  Ectopic Parathyroid Adenoma

15 minutes

120 minutes

Figure 151.3 

Figure 151.4  99mTc-sestamibi/20

Radiopharmaceutical/Dose/Procedure: SPECT/CT imaging after early pinhole imaging.

mCi/Pinhole imaging at 15 and 120 minutes,

Findings ▶ Figure 151.3: Pinhole image at 15 min (A) shows thyroid gland uptake with a focus of increased uptake near

the lower pole of the left thyroid lobe. After 120 min, there was washout from the thyroid gland, but persistent focal uptake. ▶ Figures 151.2 and 151.4: SPECT/CT images localize the focal uptake to a soft tissue mass in the paraesophageal groove. Surgical resection demonstrated a descended (ectopic) superior parathyroid adenoma (4.5 g) and a normal left inferior parathyroid gland.

Differential Diagnosis ▶ Parathyroid adenoma ▶ Parathyroid carcinoma ▶ Hyperplastic lymph node ▶ Non-parathyroid tumor ▶ Brown adipose tissue (unlikely given a single focus in soft tissue). Teaching Points ▶ Less than 5% of parathyroid adenomas are in an ectopic location and can be found anywhere throughout the neck and mediastinum, depending on the embryological migration of the gland.

▶ An ectopically descended superior parathyroid gland is commonly located in the posterior mediastinum

(e.g., retroesophageal or tracheoesophageal groove) and may mimic an inferior parathyroid adenoma on planar imaging. However, the possibility of descended superior parathyroid adenoma should be raised if the abnormality is located posterior to the expected location of parathyroid glands on SPECT imaging. ▶ When localizing ectopic parathyroid adenomas in the mediastinum, SPECT/CT can increase specificity.

Management ▶ Imaging is not necessary for the diagnosis of hyperparathyroidism, but preoperative localization can identify and localize an ectopic parathyroid adenoma, which can guide the surgical approach and limit surgical exploration.

▶ See other parathyroid cases. Further Readings

Kim SC, et al. Appearance of descended superior parathyroid adenoma on SPECT parathyroid imaging. Clin Nucl Med. 2007;32: 90–93. Nichols KJ, Tomas MB, Tronco GG, et al. Preoperative parathyroid scintigraphic lesion localization: accuracy of various types of readings. Radiology. 2008 Jul;248:221–232. Okuda I, et al. Diagnostic localization of ectopic parathyroid lesions: developmental consideration. Jpn J Radiol. 2010;28:707–713.

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Case 152 History ▶ A 39-year-old woman with hyperparathyroidism; serum calcium 12.1 mg/dl (reference 8.0–10.2), PTH 166 mg/dl (reference 5–60).

10 minutes

105 minutes

Image courtesy of Christopher Palestro, MD, North Shore-LIJ Health System.

Figure 152.1 

CORONAL

SAGITTAL

TRANSAXIAL

Image courtesy of Christopher Palestro, MD, North Shore-LIJ Health System.

Figure 152.2 

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Case 152  Parathyroid Adenoma/Thymoma (Mixed Type)

CORONAL

10 minutes

SAGITTAL

TRANSAXIAL

105 minutes

Figure 152.3 

Figure 152.4  99mTc-sestamibi/20

Radiopharmaceutical/Dose/Procedure: SPECT/CT imaging after early pinhole imaging.

mCi/pinhole imaging at 10 and 105 minutes,

Findings ▶ Figure 152.3: Pinhole image of the neck at 10 minutes shows uptake in the expected location of the thyroid

gland. After 105 minutes, there is partial washout of tracer from the thyroid gland, with prominent residual uptake near the inferior pole of the left thyroid lobe. A planar image (right panel) shows a focus of mild uptake in the mediastinum. ▶ Figure 152.4: SPECT and SPECT/CT images localize the focal uptake to the anterior mediastinum, correlating with a soft tissue mass in the left thymus. Surgical resection demonstrated a left inferior parathyroid adenoma in the neck and a thymoma (mixed type) in the anterior mediastinum.

Differential Diagnosis ▶ Parathyroid adenoma ▶ Parathyroid carcinoma ▶ Non-parathyroid tumor (e.g., thymoma) ▶ Brown adipose tissue (unlikely given a single focus). Teaching Points ▶ An ectopic parathyroid adenoma will be found in less than 5% of patients with primary hyperparathyroidism. ▶ See also Case 151. ▶ An ectopic inferior parathyroid gland typically is found in the anterior mediastinum. However, since this patient has an ipsilateral inferior parathyroid adenoma, the anterior mediastinal focus is unlikely to represent an ectopic inferior parathyroid adenoma.

Management ▶ See previous parathyroid cases. ▶ If a 99mTc-sestamibi parathyroid scan identifies a lesion that could be a non-parathyroid process, further evaluation with additional imaging or tissue biopsy may be appropriate.

Further Readings Chien D, et al. Imaging of parathyroid glands. Otolaryngol Clin North Am. 2010;43:399–415. Nichols KJ, et al. Preoperative parathyroid scintigraphic lesion localization: accuracy of various types of readings. Radiology. 2008 Jul;248:221–232. Okuda I, et al. Diagnostic localization of ectopic parathyroid lesions: developmental consideration. Jpn J Radiol. 2010;28:707–713. Zerizer I, et al. Anatomical and functional localization of ectopic parathyroid adenomas: 6-year institutional experience. Nucl Med Commun. 2011;32:496–502.

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Part 11

Radionuclide Therapy and Pre-Therapy Evaluation Heather A. Jacene, Frederick D. Grant, Katherine A. Zukotynski, Chun K. Kim

Case 153 History ▶ For each patient with hyperthyroidism, what is the likely diagnosis, and how would you determine the appropriate administered activity of 131I for therapy?

Figure 153.1 

Figure 153.2 

Figure 153.3 

A

B

Before 131I therapy

6 months after 131I therapy

Figure 153.4 

327

Case 153 

131I Therapy of Hyperthyroidism

A

Figure 153.5 

Figure 153.6 

Figure 153.7 

B

Figure 153.8 

Radiopharmaceutical/Dose/Procedure: 123I-sodium iodide/0.4 mCi/thyroid scans.

Findings ▶ Figure 153.5: Graves disease ▶ Figure 153.6: Autonomous nodule with partial suppression of the normal thyroid, which contains multiple nonfunctioning nodules.

▶ Figure 153.7: Autonomous (“hot”) nodule with marked suppression of the remaining thyroid. ▶ Figure 153.8: Autonomous (“hot”) nodule with complete suppression of the normal thyroid (A) and return of function in the normal thyroid after 131I therapy (B).

Teaching Points ▶ The aim of radioiodine therapy is complete ablation of the thyroid gland, although 5%–10% of patients may require repeat therapy.

▶ Multiple approaches to determining the administered activity of 131I: ■ Fixed, empiric administered activity, which is not tailored to the individual patient; typically, 7–15 mCi for Graves disease and 15–29 mCi for a toxic nodule.

■ Empiric administered activity corrected for radioactive iodine uptake, which does not account for thyroid mass.

■ Adjust the administered activity for both radioactive iodine uptake and thyroid (or nodule) size: 131I

administered activity (mCi) = (mCi/g) × estimated thyroid weight (g)/RAIU (range 0.00–1.00). The recommended activity (mCi/g) is 0.1–0.2 mCi/g of thyroid gland for Graves disease and 0.2–0.4 mCi/g of nodule for a toxic nodule. ■ A few centers perform thorough thyroid dosimetry, but there is no clear evidence of clinical benefit. ▶ Pre-therapy considerations: Stop anti-thyroid medications for 3 days, consider a low iodine diet for up to 2 weeks. ▶ Post-therapy considerations: Anti-emetics (especially with high 131I dose), sour candy to stimulate salivary excretion, and for severe thyrotoxicosis, consider restarting anti-thyroid medications 3–4 days after 131I. ▶ Pregnancy is an absolute contraindication, and most guidelines suggest delaying pregnancy for 6 months after therapy.

Management ▶ Explain possible risks, complications, and radiation precautions. ▶ See the SNMMI guideline for more details. Further Reading Silberstein EB, et al. The SNMMI practice guideline for therapy of thyroid disease with 131I 3.0. J Nucl Med. DOI: 10.2967/ jnumed.112.105148

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Case 154 History ▶ Three patients with differentiated thyroid carcinoma are evaluated for 131I therapy and undergo diagnostic

scans prior to therapy. Thyroid hormone was discontinued 6 weeks ago. ■ Patient A underwent near-total thyroidectomy 3 months ago. ■ Patients B and C both had thyroidectomy followed by 131I ablation therapy 2 years ago, but each now returns with an elevated serum thyroglobulin. What is the aim of 131I administration in each patient? What might be an appropriate administered activity of 131I for each?

Patient A

Patient B

Patient C

Figure 154.1 

329

Case 154 

131I Therapy of Differentiated Thyroid Cancer

Patient A

Patient B

Patient C

Figure 154.2  Radiopharmaceutical/Dose/Procedure: 123I/2–5 mCi/whole body scan performed 24 hours after 123I.

Findings ▶ Patient A: Two foci of remnant thyroid tissue in the anterior neck. ▶ Patient B: Numerous iodine-avid lymph node metastases in the neck/mediastinum and bilateral pulmonary metastases.

▶ Patient C: No iodine-avid disease identified; physiological iodine accumulation in salivary glands, saliva, nasal secretions, and stomach, with excreted iodine in bowel and urinary tract.

Teaching Points ▶ 131I is a standard therapy for differentiated (papillary or follicular) thyroid cancer. ▶ Serum TSH should be at least 30 mIU/ml before an 123I scan or 131I therapy. This can be accomplished by withdrawing thyroid hormone or administering recombinant human TSH.

▶ Formal dosimetry typically is not performed unless extensive lung metastases raise concern for pulmonary radiation toxicity.

Management ▶ The goal of therapy and administered 131I activity depends on the clinical circumstances: ■ Remnant ablation (30–100 mCi 131I) after near-total thyroidectomy without known metastatic disease (A). Ablation of remnant thyroid tissue facilitates patient follow-up with serum thyroglobulin and/or 123I scan. Not all clinicians perform a diagnostic 123I scan before remnant ablation. ■ Treatment of suspected microscopic metastatic disease (75–150 mCi 131I) after surgical resection of involved cervical lymph nodes. ■ Treatment of loco-regional lymph node involvement (75–150 mCi) identified at surgery or on 123I scan. Some clinicians recommend surgical resection of involved lymph nodes before 131I therapy. ■ Treatment of distant metastases (150–200 mCi) identified on whole body scan (B). Distant metastases are uncommon, but typically are in lung and bone. ■ Empiric treatment (100–200 mCi) of patients whose thyroglobulin is elevated with a negative 123I scan. Alternatively, 18F-FDG PET/CT may be considered in these patients (Figure 146.4). ▶ Treatment of thyroid cancer is an evolving field, and close collaboration with the referring endocrinologist is essential. Further Readings Silberstein EB, et al. The SNMMI practice guideline for therapy of thyroid disease with 131I 3.0. J Nucl Med. DOI: 10.2967/ jnumed.112.105148 Van Nostrand D, Wartofsky L. Radioiodine in the treatment of thyroid cancer. Endocrinol Metab Clin North Am. 2007 Sep;36(3):807–822.

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Case 155 History ▶ A 44-year-old woman with ovarian cancer, with peritoneal micrometastases and malignant ascites, is referred for intraperitoneal P-32 Instillation.

A

B

Figure 155.1 

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Case 155 Peritoneal Scintigraphy Before Intraperitoneal 32P Instillation A

B

Figure 155.2 

Radiopharmaceutical/Dose/Procedure ▶ 3–5 mCi 99mTc-sulfur colloid is instilled into the peritoneal cavity, followed by infusion of 200–300 mL saline. The patient rolls from side to side several times for 10–15 minutes to promote intraperitoneal distribution of radiotracer as evenly as possible. Delayed images may be obtained up to 24 hours, if necessary. ▶ Once desirable intraperitoneal distribution of 99mTc-sulfur colloid is ascertained, 10–20 mCi 32P-chromic phosphate colloidal suspension in 500 mL saline is instilled into the peritoneal cavity.

Findings ▶ Figure 155.1(A): Typical normal tracer distribution throughout the peritoneal cavity with no evidence of loculation. ▶ Figure 155.1(B): Radioactive markers (broken arrows) are placed along the right costal margin and symphysis pubis.

Differential Diagnosis ▶ Not applicable. Teaching Points ▶ 32P is a pure β- emitter. ▶ Pre-therapy imaging with 99mTc-sulfur colloid (same particle size as that of 32P-chromic phosphate) is

routinely performed to exclude loculation due to adhesions and scars as accumulation of 32P in a loculation could result in a high local radiation dose to adjacent bowel. ▶ 32P treatment has been reported to be associated with late bowel complications. ▶ Some investigators have used a lower administered activity of 32P (5 mCi) combined with platinum analogue chemotherapy.

Management ▶ Intraperitoneal instillation of 32P-chromic phosphate has been used with variable success for palliative management of malignant ascites due to disseminated intraperitoneal ovarian cancer.

▶ Intraperitoneal 32P treatment has been reported to improve prognosis in patients with peritoneal mucinous carcinomatosis of appendiceal origin.

▶ Patients should be observed for nausea, vomiting, abdominal cramping, and development of radiation peritonitis. Further Readings Pattillo RA, et al. Phosphorus-32-chromic phosphate for ovarian cancer: I. Fractionated low-dose intraperitoneal treatments in conjunction with platinum analog chemotherapy. J Nucl Med. 1995 Jan;36(1):29–36. Schomas DA, et al. Intraperitoneal treatment for peritoneal mucinous carcinomatosis of appendiceal origin after operative management: long-term follow-up of the Mayo Clinic experience. Ann Surg. 2009;249(4):588–595.

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Case 156 History ▶ A 13-year-old female with metastatic cancer (images in Figure 156.1 in posterior projection).

Pre-therapy

2 months post-therapy

Figure 156.1 

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Case 156 123I-MIBG Scans Before and After 131I-MIBG Therapy of Neuroblastoma

Pre-therapy

2 months post-therapy

Figure 156.2  Radiopharmaceutical/Dose/Procedure: 123I-metaiodobenzylguanidine (123I-MIBG)/5 mCi/Diagnostic (preand post-therapy) whole body imaging at 24 hours; 131I-MIBG/639 mCi by intravenous infusion/Therapy.

Findings ▶ Pre-therapy (123I-MIBG) scan: Numerous sites of MIBG-avid osseous neuroblastoma metastases in the skull,

left scapula, and pelvis. There is no MIBG-avid intra-abdominal disease, but there is expected uptake of 123I-MIBG in salivary glands, thyroid, myocardium, liver, and muscle. In children, MIBG uptake can occur in brown adipose tissue. There is physiologic excretion of tracer in the urinary and gastrointestinal tracts ▶ Post-therapy (123I-MIBG) scan: Interval resolution of MIBG-avid metastatic disease with typical normal biodistribution of 123I-MIBG (see also Case 133).

Differential Diagnosis ▶ Metastatic neuroblastoma ▶ Metastatic pheochromocytoma ▶ Multiple or metastatic paragangliomas. Teaching Points ▶ 131I-MIBG is an investigational orphan drug used at many centers for treatment of resistant

sympathochromaffin tumors, including high-risk neuroblastoma, metastatic pheochromocytoma, and metastatic paraganglioma. ▶ Response rates can vary depending on tumor-type and stage. ▶ Most centers administer up to 1000 mCi 131I-MIBG per treatment once or twice to a patient, but a few centers administer smaller activities on a monthly regimen. ▶ Early trials used 131I-MIBG alone, but many clinical trials are now using 131I-MIBG in combination with chemotherapy.

Management ▶ Due to the high administered activity of 131I, special nursing care and radiation safety precautions are required.

▶ 131I-MIBG therapy requires a multidisciplinary team, including professionals from oncology, nuclear medicine, radiation safety, and nursing.

Further Reading Shusterman S, et al. Iodine-131–labeled meta-iodobenzylguanidine therapy of children with neuroblastoma: Program planning and initial experience. Sem Nucl Med. 2011;41:354–363.

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Case 157 History ▶ An 80-year-old man with prostate carcinoma and pain associated with widespread bone metastases

had a 99mTc-MDP bone scan (Figure 157.1[A]‌) and a few days later received a radiopharmaceutical for bone pain palliation. Images shown in Figure 157.1(B) were obtained 24 hours later. What is the radiopharmaceutical and its indications/contraindications? A

ANT

B

POST

ANT

POST

Figure 157.1 

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Case 157  Samarium Therapy for Bone Pain Palliation Radiopharmaceutical/Dose/Procedure ▶ Day 1: 99mTc-MDP/20 mCi/Bone scan pre-samarium therapy (required to be within 8 weeks before samarium therapy).

▶ Day 2: 153Sm-EDTMP therapy, 1 mCi/kg, administered IV over 1–2 minutes and flushed with 10–20 mL of saline. ▶ Day 3: Post-therapy samarium bone scan acquired either on the same day or after 24 hours (Figure 157.1[B]‌). Findings ▶ Identical multifocal, diffusely increased 99mTc-MDP and 153Sm-EDTMP uptake in the entire axial and proximal appendicular skeleton.

▶ Multifocal activity projecting over the pelvis seen only on MDP scan due to contamination. ▶ No bladder activity on 153Sm-EDTMP scan because imaging was performed after 24 hours in this patient. Differential Diagnosis ▶ None, other than widespread osseous metastases. Teaching Points ▶ Skeletal metastases can cause pain. ▶ Alleviation of pain often requires the use of medications such as NSAIDs and opioids. However, these have

significant side effects such as GI bleeding, constipation, lethargy, and changes in mental status. ■ Bisphosphonates interfere with osteoclast activity and stimulate bone formation. In the setting of bone metastases, bisphosphonates can reduce skeletal complications and delay progression. ■ Radiation therapy or surgery can relieve pain from localized osseous metastatic disease. ■ Radiation therapy should be considered for pain from acute spinal cord compression. ■ Radiopharmaceuticals are helpful for pain relief from mutifocal osseous metastatic disease. ▶ Radiopharmaceuticals used for bone pain palliation in the United States include: 32P-phosphate, 89Sr-chloride, 153Sm-EDTMP, and 223Ra-dichloride. ■ Efficacy, duration of pain relief, toxicity, expense, and ability for repetitive therapy differ between radiopharmaceuticals. ■ Among them, imaging can be performed only with 153Sm-EDTMP. ▶ 153Sm-EDTMP (ethylenediaminetetramethylene phosphonic acid), a phosphonate complex taken up by the skeleton in proportion to osteoblastic activity, has been the most commonly used in the United States. 99mTc-MDP and 153Sm-EDTMP distributions are identical. ▶ Indications: Multiple painful osseous metastases (> 1 site) on bone scan. ▶ Contraindications: ■ Absolute: Pregnancy; breastfeeding ■ Others: Renal failure; spinal cord compression; hemoglobin < 9 g/dL; total white cell count < 3.5 x 109/L; absolute neutrophil count < 1.5 x 109/L; platelets < 100 x 109/L; GFR < 30 mL/min. ■ Blood work should be obtained 1 week before therapy. ▶ At 5 hours after administration, < 1% of 153Sm-EDTMP remains in the circulation. After 6 hours, urinary excretion of the radiopharmaceutical is minimal. ▶ Bone pain palliation occurs in > 50% of patients. Bone marrow suppression is typically mild. The platelet and WBC nadir typically occurs in 2–4 weeks and recovers by 8 weeks. ▶ Retreatment can be considered, generally after an interval of 3 months from prior therapy.

Management ▶ 153Sm-EDTMP was given intravenously and the bone pain improved. Further Readings Pandit-Taskar N, et al. Radiopharmaceutical therapy for palliation of bone pain from osseous metastases. J Nucl Med. 2004;45(8):1358–1365. Paes F, Serafini A. Systemic metabolic radiopharmaceutical therapy in the treatment of metastatic bone pain. Semin Nucl Med. 2010;40:89–104.

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Case 158 History ▶ A 65-year-old man with castration-resistant prostate cancer and low back pain. No visceral

metastases. Evaluation for radium-223 dichloride therapy for bone metastases. Last complete blood count: platelet count 137,000/mm3; absolute neutrophil count 2,500/mm3; hemoglobin 13.5 g/dL.

Figure 158.1 

337

Case 158  Radium-223 Dichloride Therapy for Bone Metastases

Figure 158.2 

Radiopharmaceutical/Dose/Procedure ▶ Figure 158.2: 99mTc-MDP/25 mCi/Bone scan ▶ 223Ra-dichloride/1.35 microCi per kg/Therapy for bone metastases. Findings ▶ Bone scan: Scattered focal areas of increased radiotracer uptake throughout the skeleton consistent with metastases ▶ Appropriate candidate for therapy with radium-223 dichloride. Differential Diagnosis ▶ Not applicable. Teaching Points ▶ 223Ra-dichloride is a bone seeking alpha-emitting radiotherapeutic agent currently indicated for patients with

symptomatic bone metastases from castration-resistant prostate cancer and no known visceral metastatic disease.

▶ In contrast to samarium-153 and strontium-89, radium-223, given in addition to best standard of care, has

been shown to improve survival compared with placebo for men with castration-resistant prostate cancer and bone metastases. ▶ Therapy schema ■ 6 injections of radium-223 given at 4-week intervals ■ Dosage: 50 kBq/kg (1.35 microcuries/kg), by slow intravenous injection over 1 minute ▶ Bone marrow suppression is a common short-term side effect. Complete blood counts (CBC) should be performed at baseline and prior to each dose of radium-223. ■ Baseline CBC requirements: platelet count ≥ 100,000/mm3; absolute neutrophil count ≥ 1,500/mm3; hemoglobin ≥ 10 g/dL ■ CBC requirements before doses 2–6: platelet count ≥ 50,000/mm3; absolute neutrophil count ≥ 1,000/mm3 ◆ Subsequent doses of radium-223 can be delayed for up to 6–8 weeks between injections to allow recovery of blood counts. Supportive care can be administered as needed. ▶ Most common non-hematologic side effects: nausea, diarrhea, vomiting, peripheral edema ▶ Close collaboration between oncology and nuclear medicine is essential. ▶ Handling of radium-223 before, during, and after administration should follow local and national regulations for radiation safety.

Management ▶ Proceed with administration of radium-223 for symptomatic bone metastases from castration-resistant prostate cancer.

Further Reading Parker C, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med. 2013;369(3):213–223.

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Case 159 History ▶ A 56-year-old man with recurrent non-Hodgkin lymphoma (NHL). Diagnosed 5 years prior

with stage IV, CD20 positive, grade 1 follicular NHL. Treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Remained in remission until PET/CT scan demonstrated recurrent FDG-avid disease in left external iliac lymph nodes. Blood counts at time of FDG-PET/CT scan: platelets 167,000/mm3; absolute neutrophils 2,000/mm3; normal renal and hepatic function. Bone marrow biopsy: no involvement by lymphoma. Referred for treatment with radioimmunotherapy. See Figure 159.1.

Figure 159.1 

339

Case 159 Radioimmunotherapy-1

Figure 159.2  Radiopharmaceutical/Dose/Procedure: 18F-FDG/10-15 mCi/PET-CT 1 hour after injection.

Findings ▶ Appropriate candidate for therapy with radiolabeled anti-CD20 monoclonal antibody therapy. Differential Diagnosis ▶ Not applicable. Teaching Points ▶ Approved radioimmunotherapy regimens for treatment of NHL ■ Rituximab and 90Y-ibritumomab tiuxetan (Zevalin®, Spectrum Pharmaceuticals) ■ Tositumomab and 131I-tositumomab (Bexxar®, GlaxoSmithKline) ▶ Both target the CD20 antigen, which is found on 95% of B-cell lymphomas ▶ Indications for treatment: ■ Relapsed or refractory, low-grade, follicular, or transformed B-cell NHL ■ Previously untreated follicular NHL after partial or complete response to first-line chemotherapy

(rituximab and 90Y-ibritumomab tiuxetan). ▶ General eligibility criteria for treatment ■ Appropriate CD20-positive NHL ■ Adequate blood counts (platelets > 100,000/mm3; absolute neutrophil counts > 1,500/mm3) ■ < 25% tumor involvement in the bone marrow ■ Good renal function (tositumomab and 131I-tositumomab). ▶ Therapy schema includes two steps for both agents: ■ For tositumomab and 131I-tositumomab, biodistribution/dosimetry step to assure the antibody biodistribution is normal and to determine the patient-specific amount of radioactivity to administer. For rituximab and 90Y-ibritumomab tiuxetan, unlabeled rituximab step with imaging no longer required. ■ Therapeutic step ■ Unlabeled antibody is administered prior to administration of labeled antibody to block readily assessable CD20 antigen on normal B-cells in the spleen and peripheral blood. This improves tumor targeting of the radiolabeled antibodies. ▶ Major short-term side effects are significant hematologic toxicity. ■ Thrombocytopenia and neutropenia occurs in 60%–70% of patients ■ Transient, with nadirs typically occurring at 4–7 weeks after treatment ■ Close monitoring with at least weekly blood counts for 12 weeks or until recovery ■ 15–27% of patients require hematologic support. ▶ Long-term side effects: human anti-mouse/chimeric antibodies (4–11%); hypothyroidism (131I-tositumomab, 18%), myelodysplastic syndrome/leukemia (2–4%) ▶ Close collaboration between oncology and nuclear medicine is needed.

Management ▶ Proceed with administration of radioimmunotherapy for NHL. Further Readings Goldsmith SJ. Radioimmunotherapy of lymphoma: Bexxar and Zevalin. Semin Nucl Med. 2010;40:122–135. Wahl RL. Tositumomab and (131)I therapy in non-Hodgkin’s lymphoma. J Nucl Med. 2005;46(suppl 1):128S–140S. Semin Nucl Med. 2004 Jan;34(1 suppl 1).

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Case 160 History ▶ A 56-year-old man with recurrent CD20+ low-grade follicular non-Hodgkin lymphoma. 24 hours

Anterior

72 hours

Posterior

Anterior

Posterior

Figure 160.1 

341

Case 160  Biodistribution of Ibritumomab Tiuxetan (Zevalin®) 24 hours

Anterior

72 hours

Posterior

Anterior

Posterior

Figure 160.2  Radiopharmaceutical/Dose/Procedure: 111In-ibritumomab tiuxetan/5 mCi/Anti-CD20 antibody imaging.

Findings ▶ 24-hour images: Moderately high activity in the heart > liver and spleen; moderate activity in other blood pool areas; moderately low or very low uptake in the kidneys, bowel, and bone marrow

▶ 72-hour images: Same as 24-hour images, except activity in the heart has decreased and is now similar to the

liver; focal moderate uptake in the left iliac/inguinal region (arrows) in the location of FDG-avid lymph nodes on PET/CT (see Case 159, Radioimmunotherapy-1).

Differential Diagnosis ▶ Normal biodistribution of 111In-ibritumomab tiuxetan at 24 and 72 hours ▶ Uptake in non-Hodgkin lymphoma tumor in the left iliac/inguinal region. Teaching Points ▶ 90Y is a pure β-emitter and is not used for imaging. Biodistribution of 90Y-ibritumomab tiuxetan can be

assessed with 111In-ibritumomab tiuxetan, with whole body planar images typically obtained 48–72 hours after radiotracer injection. Abnormal patterns of biodistribution include: ■ Intense uptake in the liver, spleen, bone marrow, indicating reticuloendothelial system uptake ■ Increased uptake in normal organs (not involved with tumor) such as the lungs or kidneys greater than the liver or fixed areas of uptake in the bowel greater than the liver ■ Prominent uptake in the bone marrow is rare (< 0.5%) and should be evaluated for etiology such as involvement by lymphoma, recent hematopoietic growth factor administration, human anti-mouse or anti-chimeric antibodies. ▶ Correlations between visualization of tumor on biodistribution images and tumor response have not been demonstrated. ▶ Biodistribution imaging studies with 111In-Ibritumomab tiuxetan are no longer required prior to administration of therapeutic 90Y-ibritumomab tiuxetan because abnormal biodistribution is rare and no differences have been shown in hematologic toxicity between patients who underwent and did not undergo biodistribution imaging studies. ▶ Therapeutic dosage for 90Y-ibritumomab tiuxetan is based on platelet count and body weight: ■ 14.8 MBq/kg (0.4 mCi/kg) for platelets > 150,000/mm3 ■ 11.1 MBq/kg (0.3 mCi/kg ) for platelets 100,000–150,000/mm3

Management ▶ Proceed with administration of the therapeutic dosage of 90Y-ibritumomab tiuxetan. Further Reading See Case 159 (Radioimmunotherapy-1).

342

Case 161 History ▶ A 62-year-old woman with recurrent CD20+ low-grade follicular non-Hodgkin lymphoma. Day 3

Day 0

Anterior

Posterior

Anterior

Day 6

Posterior

Anterior

Posterior

Figure 161.1 

343

Case 161  Biodistribution of Tositumomab (Bexxar®) Day 3

Day 0

Anterior

Posterior

Anterior

Day 6

Posterior

Anterior

Posterior

Figure 161.2  Radiopharmaceutical/Dose/Procedure: 131I-tositumomab/5 mCi/Anti-CD20 antibody imaging.

Findings ▶ Day 0: most of the activity is in the blood pool; uptake in the liver and spleen is less than that in the heart. ▶ Days 3 and 6: activity in the blood pool has declined; decreased overall counts and accumulation in the liver and spleen.

Differential Diagnosis ▶ Normal biodistribution of 131I-tositumomab at Days 0, 3, and 6. Teaching Points ▶ There is significant patient-to-patient variability in the clearance rates of 131I-tositumomab; therefore,

dosimetry is performed, along with the visual assessment of biodistribution for the tositumomab therapeutic regimen. ▶ Anterior and posterior whole body planar images are obtained at 3 time-points after administration of the tracer dose of 131I-tositumomab (within 1 hour of tracer administration on day 0; day 2, 3, or 4; and day 6 or 7). ▶ Although very rare, patients with abnormal biodistribution should not proceed to the therapeutic step. ▶ Abnormal patterns of biodistribution include: ■ Day 0: non-visualization of blood pool, diffuse lung uptake > blood pool, intense uptake in the liver or spleen not involved with tumor; uptake suggesting urinary obstruction ■ Day 2, 3, or 4 and Day 6 or 7: diffuse lung uptake > blood pool, uptake suggesting urinary obstruction ■ From the dosimetry calculations: total body residence times < 50 hours or > 150 hours. ▶ Visualization of tumor on the biodistribution/dosimetry images is not required to proceed with treatment as correlations between visualization of tumor and tumor response have not been demonstrated. ▶ The amount of radioactivity to administer for the therapeutic dosage of 131I-tositumomab is based on dosimetry calculations for the desired total body radiation dose: ■ 75 cGy total body radiation dose for platelets > 150,000/mm3 ■ 65 cGy total body radiation dose for platelets 100,000–150,000/mm3

Management ▶ Proceed with administration of the therapeutic dosage of 131I-tositumomab. Further Reading See Case 159 (Radioimmunotherapy-1).

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Part 12

Liver, Spleen, and Biliary Tract Scott Britz-Cunningham, Hyewon Hyun, Chun K. Kim

Case 162 History ▶ A 47-year-old woman with acute abdominal pain. What should be done next?

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Figure 162.1 

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Case 162  Morphine Augmentation

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Figure 162.2 

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Figure 162.3  99mTc-mebrofenin/5

Radiopharmaceutical/Dose/Procedure: mCi/Cholescintigraphy—sequential imaging for 60 minutes (Figure 162.2) followed by post-2 mg IV morphine imaging for 30 minutes (Figure 162.3).

Findings ▶ Figure 162.2: Prompt hepatic uptake; prompt clearance of cardiac blood pool activity; tracer excretion into the intestine within 15 minutes; non-visualization of gallbladder; moderate tracer retention in the liver at 50 minutes indicating mild cholestasis. ▶ Figure 162.3: Gallbladder seen 5 minutes after morphine administration.

Differential Diagnosis (for Delayed Visualization of the Gallbladder) ▶ Chronic cholecystitis ▶ Hepatocellular dysfunction or cholestasis causing insufficient amount of bile excretion ▶ Prolonged fasting > 24 hours ▶ Insufficient fasting < 4 hours. Teaching Points ▶ Delayed or non-visualization of the gallbladder may be caused by: ■ Marked hepatocellular dysfunction or cholestasis, but probably not in this case given the amount of excreted bile during the first 60 minutes.

■ Insufficient fasting < 4 hours: Gallbladder may contract during the exam due to secretion of endogenous CCK.

■ Fasting > 24 hours: Gallbladder may already have nearly completely filled with bile before the exam, resulting in no further filling with tracer. CCK pre-administration is indicated.

▶ The most common cause of delayed visualization of gallbladder is chronic cholecystitis. ▶ If the gallbladder is not seen by 1 hour: ■ Low-dose morphine (0.04 mg/kg) may be administered intravenously with additional imaging for 30 minutes, or

■ Delayed imaging may be performed at 4 hours or, if necessary, later. ■ Non-visualization of gallbladder with either technique is considered consistent with acute cholecystitis.

▶ Morphine-augmented imaging has been reported to be not only more efficient (90-minute imaging vs. 4 hours) but more important, more specific than delayed imaging in excluding acute cholecystitis.

Management ▶ Patient’s symptoms resolved after elective laparoscopic cholecystectomy. Pathology revealed chronic cholecystitis.

Further Readings Cabana MD et al. Morphine-augmented hepatobiliary scintigraphy: a meta-analysis. Nucl Med Commun. 1995;16:1068–1071. Kim CK et al. Cholescintigraphy in the diagnosis of acute cholecystitis: morphine augmentation is superior to delayed imaging. J Nucl Med. 1993;34:1866–1870.

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Case 163 History ▶ A 55-year-old female with chronic right upper quadrant pain underwent a study shown in Figure 163.1. What should be done next?

Figure 163.1 

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Case 163 Importance of CCK Infusion Rate for Measurement of Gallbladder Ejection Fraction

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Figure 163.3 

Radiopharmaceutical/Dose/Procedure: ▶ Figure 163.1: 99mTc-disofenin (DISIDA)/5 mCi/Cholescintigraphy—sequential imaging for 45 minutes. ▶ Figure 163.2: Additional imaging for 45 minutes (during sincalide [synthetic CCK] 0.02 micrograms/kg infusion over 3 minutes + additional 42 minutes).

▶ Figure 163.3: Repeat imaging for 45 minutes (during sincalide infusion over 30 minutes + additional 15 minutes). Findings ▶ Figure 163.1: Prompt hepatic uptake; prompt visualization of the common bile duct, gallbladder, and small intestine; moderate clearance of liver parenchymal activity.

▶ Figure 163.2: Poor gallbladder contraction (ejection fraction < 10%) following 3-minute CCK infusion. ▶ Figure 163.3: Good gallbladder contraction (ejection fraction ~85%) during 30-minute CCK infusion. Differential Diagnosis ▶ Non-biliary gastrointestinal disease causing pain mimicking biliary-type pain. Teaching Points ▶ While delayed visualization of the gallbladder (as in Case 162) is suggestive of chronic cholecystitis, normal

gallbladder filling during the first 60 minutes does not exclude chronic cholecystitis or any other chronic biliary disorders. ▶ Gallbladder ejection fraction (GBEF) in response to CCK infusion has been used to differentiate between chronic biliary disorders, e.g., chronic cholecystitis, biliary dyskinesia, etc., and non-biliary disorders such as the irritable bowel syndrome that cause similar symptoms. ■ Although controversy exists with regard to the correlation between GBEF and histopathology, it is generally agreed that the lower the GBEF, the more likely the patient’s symptoms will be relieved by cholecystectomy. ▶ Bolus injection or short infusion of CCK as seen in Figure 163.2 typically causes supraphysiologic blood levels of CCK that could cause paradoxic decreased gallbladder contraction. ▶ In anterior projection, the gallbladder and duodenum often overlap, which may falsely lower the GBEF. Left anterior oblique projection is ideal for GBEF measurement. ▶ Some investigators recommend a 60-minute CCK infusion technique.

Management ▶ Assess for other causes of pain. Further Readings Kim CK, et al. Interventions in gastrointestinal nuclear medicine. Nuclear Med Ann. 1996:213–257. Vassiliou MC, et al. Biliary dyskinesia. Surg Clin North Am. 2008;88(6):1253–1272. Ziesman HA, et al. Sincalide-stimulated cholescintigraphy: a multicenter investigation to determine optimal infusion methodology and gallbladder ejection fraction normal values. J Nucl Med. 2010;51(2):277–281.

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Case 164 History ▶ A 57-year-old man with acute right upper quadrant pain underwent a hepatobiliary scan to exclude

acute cholecystitis. The patient has not eaten for more than 24 hours. Images obtained for 60 minutes (reformatted to 3 minutes/frame) are shown in Figure 164.1.

Figure 164.1 

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Case 164  Normal Variant: Preferential Gallbladder Filling

Figure 164.2 

Figure 164.3 

Radiopharmaceutical/Dose/Procedure: Pre-treatment with CCK followed by 99mTc-mebrofenin/5 mCi/ Cholescintigraphy—sequential imaging for 60 minutes (Figure 164.2); re-administration of CCK with sequential imaging for additional 30 minutes (Figure 164.3).

Findings ▶ Figure 164.2: ■ Mild to moderately decreased hepatic uptake and mild to moderately delayed clearance of blood pool and liver parenchymal activity suggestive of hepatocellular dysfunction

■ Prompt visualization of the gallbladder before 10 minutes ■ Continued gallbladder filling without bowel excretion of radiotracer even by the end of the first hour.

▶ Figure 164.3: Excretion of radiotracer into the duodenum 4–7 minutes after re-administration of CCK. Differential Diagnosis (for Absent Bowel Excretion Before Re-administration of CCK) ▶ Normal variant due to a tightly closed sphincter of Oddi in fasting state ■ Following CCK pretreatment before the exam ■ Normal fasting state ▶ Administration of narcotics before the exam.

Teaching Points ▶ CCK pre-treatment is the most common cause of prompt and preferential filling of gallbladder without excretion into the duodenum.

▶ Although less common, this finding can also be seen in normal fasting state. ▶ Hyperacute common bile duct obstruction used to be included in the differential, and to exclude it, second

dose of CCK was given to demonstrate prompt bowel excretion. However, experience and data in the literature have shown that CBD obstruction associated with this scnitigraphic pattern is virtually nonexistent, and thus administration of second CCK unnecessary unless GBEF measurement is clinically indicated.

Management ▶ On follow-up visit, patient was found to have a renal stone. Further Readings Kim CK. Pharmacologic intervention for the diagnosis of acute cholecystitis: cholecystokinin pretreatment or morphine, or both? J Nucl Med. 1997;38(4):647–649. Kim CK, et al. Delayed biliary-to-bowel transit in cholescintigraphy after cholecystokinin treatment. Radiology. 1990;176:553–556. Lee SO, et al. Is CCK necessary to separate normal from CBD obstruction when prompt gallbladder filling but no bowel activity is seen during cholescintigraphy? J Nucl Med. 1991;32:976.

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Case 165 History ▶ A 55-year-old woman with a history of right hemicolectomy for colon cancer presented with

confusion and fever of 101.6°. She was anicteric at presentation. Her white cell count was normal, but showed a marked left shift with bandemia. Liver function tests were normal. On physical examination, there was a questionable Murphy sign. Abdominal CT did not show gallstones but there was thickening of the gallbladder wall, with pericholecystic fat stranding. Immediately adjacent to the gallbladder, there was a 6 × 3.9 × 4.5 cm fluid collection, accompanied by reactive hyperemia in the hepatic segment 4.

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Figure 165.1 

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Case 165  Acute Acalculous Cholecystitis With Rim Sign

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Figure 165.2  Radiopharmaceutical/Dose/Procedure: minutes and delayed imaging at 4 hours.

Figure 165.3  99mTc-mebrofenin/5

mCi/Cholescintigraphy—sequential imaging for 60

Findings ▶ Cholescintigraphy (Figure 165.2): ■ Rapid hepatic uptake and clearance of radiotracer ■ Prompt appearance of radioactivity in the small bowel, excluding CBD obstruction ■ No gallbladder visualization up to 4 hours ■ A rim of increased activity adjacent to the gallbladder fossa (“rim sign”), becoming more prominent with time (arrows)

▶ CT (Figure 165.3): ■ No gallstones, thickened gallbladder wall, and pericholecystic stranding ■ A fluid collection is seen in the gallbladder fossa (arrow), with reactive hyperemia in hepatic segment 4. Differential Diagnosis ▶ Acute acalculous cholecystitis with transmural inflammation indicated by rim sign ▶ Gangrenous cholecystitis ▶ Pericholecystic abscess ▶ Focal biliary ductal dilatation. Teaching Points (“Rim Sign”) ▶ Etiology: Hyperemia (causing increased tracer delivery) and delayed excretion (causing relatively increased

tracer retention) in the hepatic parenchyma surrounding the gallbladder fossa ■ Hepatocytes in this region are functional and readily take up and excrete the radiotracer. Edema from inflammation in the gallbladder fossa may compress and cause stasis in adjacent small bile canaliculi, resulting in delayed excretion of the radiotracer. ▶ Rim sign (when present): ■ Increases the specificity of the test for acute cholecystitis, but not the sensitivity. ■ Increases the likelihood of complicated (e.g., gangrenous) cholecystitis but is not specific for this; can affect surgical management and should be reported whenever present.

Management ▶ Percutaneous cholecystotomy tube placed, yielding purulent drainage material. ▶ The patient was started on antibiotic therapy and was discharged to home care with the cholecystotomy tube in place. Two months later, the pericholecystic fluid had completely resolved, and a cholecystectomy was performed. Histologic examination at that time showed only residual chronic cholecystitis.

Further Readings Cawthon MA, et al. Biliary scintigraphy: the “hot rim” sign. Clin Nucl Med. 1984;9(11):619–621. McDonald KL, Davani M. The rim sign in hepatic abscess: case report and review of the literature. J Nucl Med. 1997;38(8):1282–1283. Shih WJ, et al. Scintigraphic findings in acute gangrenous cholecystitis. Clin Nucl Med. 1987;12(9):717–720.

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Case 166 History ▶ A 57-year-old male with early cirrhosis, presented with abdominal pain.

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Case 166  Right Portal Vein Thrombosis

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Figure 166.2  Radiopharmaceutical/Dose/Procedure: 99mTc-mebrofenin/5 mCi/Cholescintigraphy—sequential imaging for 60 minutes.

Findings ▶ Delayed blood pool clearance ▶ Asymmetric decreased radiotracer in the right lobe compared with the left ▶ Slightly delayed hepatobiliary transit; GB visualization by 30 minutes (arrows), confirmed by additional images taken from different projections (not shown)

▶ Radiotracer in the small bowel indicating patent common bile duct. Differential Diagnosis ▶ Hepatocellular dysfunction, right lobe worse than left without obstruction ▶ Partial occlusion of right portal vein by thrombosis or tumor ▶ Partial occlusion of right hepatic vein by thrombosis or tumor. Teaching Points ▶ Must evaluate hepatic uptake for its quality, homogeneity, and prompt or delayed washout. ▶ If suspect vascular etiology, perform Doppler ultrasound; alternatively, contrast-enhanced CT with portal

venous phase imaging or MRA can demonstrate the thrombus and identify underlying abnormality/mass. F-18 FDG PET CT may aid in differentiating bland from malignant thrombus. ▶ Portal vein thrombosis can be due to multiple causes, including reduced flow from both benign and malignant processes (cirrhosis, primary or metastatic malignancy), hypercoagulable state, local inflammation or infection such as with acute pancreatitis, cholangitis, and recent abdominal surgery. ▶ Treatment depends on etiology of the portal vein thrombosis, particularly whether the patient has cirrhosis or not.

Management ▶ Patient was found to have hepatocellular caricnoma with involvement of the right portal vein on follow-up enhanced CT.

Further Readings Hu S, et al. The role of 18F-FDG PET/CT in differentiating malignant from benign portal vein thrombosis. Abdom Imaging. 2014;39(6):1221–1227. Sun L, e al. Highly metabolic thrombus of the portal vein: 18F FDG PET/CT demonstation and clinical significane in hepatocellular carinoma. World J Gastroenterol. 2008 Feb 28:14(8)1212–1217.

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Case 167 History ▶ A 38-year-old man underwent a laparoscopic cholecystectomy after an episode of gallstone

pancreatitis. He complained of worsening abdominal pain, nausea, and bilious vomiting for 1 week after surgery. His serum bilirubin rose to 3.4 from a postoperative value of 1.4. An ultrasound exam showed fluid in the gallbladder fossa, consistent with expected postsurgical changes. Abdominal CT similarly showed a small amount of fluid in the gallbladder fossa, with a normal-appearing common bile duct.

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Figure 167.1 

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Case 167  Bile Leak

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Figure 167.2 

Figure 167.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-mebrofenin/5 mCi/Cholescintigraphy—sequential imaging for 60 minutes.

Findings ▶ Figure 167.2: ■ Rapid hepatic uptake and clearance of radiotracer are seen. ■ Radiotracer appears promptly in the small bowel (arrows), excluding CBD obstruction. ■ Mild activity in the left upper quadrant (short arrow) could reflect either enterogastric reflux of bile (likely, given the history of bilious vomiting) or flow of leaked bile into the lesser sac.

■ Copious radiotracer activity is seen draining from a collection (arrow) in the gallbladder fossa along the inferior surface of the liver and down the right paracolic gutter into the pelvis.

▶ Figure 167.3: ■ A small amount of fluid in the gallbladder fossa (white arrow) is seen. This is a nonspecific finding in a patient 1 week after cholecystectomy.

Differential Diagnosis ▶ Post-cholecystectomy bile leak. Teaching Points ▶ Bile leak is a common complication after laparoscopic cholecystectomy. It may also be seen after abdominal

trauma or liver transplantation. A small leak will often heal and is frequently treated with percutaneous drainage; a large leak may require operative intervention. ▶ Early appearance of tracer activity in the lateral-most portion of the right abdomen is highly suggestive of a leak. However, it can be difficult to distinguish luminal intestinal activity from a leak if the leak occurs in the mid-abdomen. In that case, an anterior static image taken with the patient in lateral decubitus position will show gravity-dependent pooling of leaked activity in the free peritoneal space as long as it is not loculated. Giving the patient water may clear radiotracer activity in the duodenum.

Management ▶ A percutaneous cholecystotomy tube was placed 2 days after the exam. Further Readings Nagle CE, et al. Bile ascites in adults. Diagnosis using hepatobiliary scintigraphy and paracentesis. Clin Nucl Med. 1985;10(6):403–405. Patel M, Oates E. Postcholecystectomy bile leak. Serial hepatobiliary imaging and percutaneous drainage. Clin Nucl Med. 1988;13(11):805–807. Weissmann HS, et al. Demonstration of traumatic bile leakage with cholescintigraphy and ultrasonography. Am J Roentgenol. 1979;133(5):843–847.

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Case 168 History ▶ A 57-year-old man presented with 3 weeks of worsening right upper quadrant pain, described by the patient

as sharp, severe, intermittent, and improved with eating. He denied nausea, vomiting, or acholic stools. Sclerae were anicteric on physical exam. Ultrasound showed a mildly thickened gallbladder wall and a small amount of pericholecystic fluid, but no gallstones. Liver function tests (LFTs) were moderately abnormal: ALT 269; AST 222; alkaline phosphatase 217; TBili 1.7 and DBili 1.2. You are being asked to check the initial 60-minute images that have just been acquired (selected images shown in Figure 168.1). What is your differential diagnosis at this point, and what would you do next?

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Figure 168.1 

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Case 168  Intrahepatic Cholestasis

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Figure 168.3 

Radiopharmaceutical/Dose/Procedure: 99mTc-mebrofenin/5 mCi/Cholescintigraphy—sequential imaging for 60 minutes and delayed imaging at 18 hours.

Findings ▶ Figure 168.2: A classic “liver scan” appearance: Prompt blood pool clearance; continuous/persistent hepatic uptake; no tracer excretion into the gallbladder, common bile duct (CBD), or small bowel.

▶ Figure 168.3: Persistent hepatic activity (normally, no significant hepatic activity should be seen at 18 hrs); minimal intestinal activity (patent common bile duct); non-visualization of the gallbladder.

Differential Diagnosis ▶ Intrahepatic cholestasis (drug-induced acute hepatitis such as viral) ▶ Extrahepatic cholestasis (CBD obstruction secondary to stone, stricture, or a malignancy of the ampulla of Vater or pancreatic head), based on images up to 60 minutes but excluded by the 18-hour image.

▶ Gallbladder cannot be assessed due to minimal bile excretion.

Teaching Points ▶ LFTs can aid in differentiating intrahepatic from extrahepatic cholestasis, but can be ambiguous. ▶ Ductal dilatation on ultrasound, CT, MRI/MRCP, when present, can suggest the level of extrahepatic cause. ▶ Hepatobilary scintigraphy: ■ A classic “liver scan” appearance indicates cholestasis; the distinction between intrahepatic and extrahepatic cholestasis cannot be made on a typical 60- to 90-minute imaging protocol, and delayed imaging should be performed. ■ Visualization of intestinal activity on a delayed scan increases the likelihood of intrahepatic cholestasis. Persistent “liver scan” appearance with no small bowel activity on a delayed scan is more often associated with extrahepatic than intrahepatic cholestasis, but the latter is not excluded. ■ When significant cholestasis is present with minimal bile excretion into the intestine, non-visualization of the gallbladder does not necessarily indicate cystic duct obstruction. Delayed gallbladder visualization excludes acute cholecystitis but does not necessarily indicate chronic cholecystitis for the same reason.

Management ▶ A diagnosis of drug-induced cholestasis was made, likely attributable to Pioglitazone (Actos). Within 2 days of discontinuation of the drug, LFTs began to improve.

Further Readings Kuni CC, et al. Evaluation of intrahepatic cholestasis with radionuclide hepatobiliary imaging. Gastrointest Radiol. 1984;9(2):163–166. Trauner M, et al. Molecular pathogenesis of cholestasis. N Eng J Med. 1998;339:1217–1227.

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Case 169 History ▶ A 26-year-old heart transplant candidate complained of 3 weeks of constipation and abdominal

bloating. CT showed ascites and a nodular, cirrhotic-appearing liver with a 3.2 x 3.5 cm enhancing mass immediately superior to the anterior portion of the gallbladder, suspicious for either primary hepatocellular carcinoma or a metastasis from an unknown primary malignancy. Hepatobiliary scintigraphy was first performed. On the next day, 99mTc-sulfur colloid planar and SPECT imaging was performed.

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Figure 169.2 

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Figure 169.3 

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Case 169  Focal Nodular Hyperplasia (FNH)

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Figure 169.4  99mTc-mebrofenin/5

Radiopharmaceutical/Dose/Procedure: mCi/Cholescintigraphy (Figure 169.4), 99mTc-sulfur colloid/5 mCi/Liver-Spleen scan (Figure 169.5).

Findings ▶ 99mTc-mebrofenin: Mild focal uptake likely corresponding to the mass seen on CT apparent on earliest frames

(arrow) before any radiotracer appears in the biliary tract. Subsequently, this is obscured by increasing activity in the adjacent bile duct and gallbladder. ▶ Sulfur colloid: Mild focal uptake (dotted arrow) identical to that seen on earliest frames of the hepatobiliary scan. SPECT clearly shows that uptake in this region is greater than parenchymal uptake.

Differential Diagnosis and Teaching Points ▶ FNH: ■ Structurally disorganized bile canaliculi with delayed outflow. ■ Contains hepatocytes; takes up hepatobiliary tracer; FNH-to-normal liver ratio increase with time as rest

of liver clears (92% sensitivity for this pattern), which could not be assessed in this case because of the close proximity to gallbladder. ■ Contains Kupffer cells; takes up 99mTc-sulfur colloid equal to or greater than that of surrounding liver in 70%; up to one-third show uptake less than that of normal liver. Given this sensitivity, consider hepatobiliary scan if sulfur colloid scan is negative. ■ Tends to show increased activity on arterial phase with 99mTc-sulfur colloid or hepatobiliary agents. ▶ Hepatic adenoma contains Kupffer cells: 25% take up 99mTc-sulfur colloid. Cannot be excluded by sulfur colloid imaging alone. ▶ Hepatocellular carcinoma (HCC) including fibrolamellar carcinoma: ■ Well-differentiated HCC can take up hepatobiliary radiotracer; can show persistence on delayed imaging; cannot exclude HCC with a hepatobiliary scan alone. ■ Does not contain Kupffer cells; “cold” on sulfur colloid imaging. ▶ Metastases: “cold” on 99mTc-sulfur colloid and hepatobiliary imaging.

Management ▶ Core biopsies revealed FNH. Further Readings Biersack HJ, et al. Focal nodular hyperplasia of the liver as established by 99mTc sulfur colloid and HIDA scintigraphy. Radiology. 1980;137(1 Pt 1):187–190. Kim CK. Scintigraphic evaluation of the liver and biliary tract. In Gazelle SG, et al., eds. Hepatobiliary and Pancreatic Radiology: Imaging and Interventions. New York: Thieme; 1998:108–153.

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Case 170 History ▶ A 72-year-old man with esophageal adenocarcinoma was found to have an 8.2 x 4.6 heterogeneously enhancing mass with lobulated borders adjacent to the gallbladder and an 8.5 x 8 cm thin-walled mass consistent with a cyst at the dome of the liver on MRI. A scintigraphic study was performed. See flow image (Figure 170.1), early static image (Figure 170.2) and 2-hour delayed static image (Figure 170.3).

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Case 170  Hepatic Hemangioma

Figure 170.4  Radiopharmaceutical/Dose/Procedure: 99mTc-RBC/20 mCi/Hemangioma scan.

Findings (Figure 170.4: [From left] Early RAO View, Delayed RAO View, Axial Delayed SPECT, and MR) ▶ Flow, early static, and delayed static images show a persistent large, rounded area of decreased radiotracer activity (arrowheads), corresponding to the cyst noted on MRI (not shown).

▶ More inferiorly and adjacent to the gallbladder fossa, there is a smaller, less well-defined area of decreased

activity seen on the early RAO static view, corresponding to the area of increased activity on the delayed images (broken arrows). ▶ Lobulated area of increased activity in the right hepatic lobe on axial SPECT correlates with 8.2 x 4.6 cm mass on MR (short arrows) adjacent to the gallbladder (long white arrow).

Differential Diagnosis ▶ Hepatic hemangioma. Teaching Points ▶ The classical scintigraphic pattern of a cavernous hemangioma shows decreased activity on flow and early

images with increased activity on delayed images with very high specificity (up to 99%). ■ Initial decreased activity may not be noticeable if hemangioma is small and/or deeply situated. ■ Atypical hemangiomas may show increased early phase activity. ■ Hypervascular tumors other than hemangiomas may show increased activity on both early and delayed phases, but activity generally does not increase with time, while activity in hemagiomas does. ▶ Delayed filling classically progresses inward from periphery, but this is variable. ▶ Planar imaging has limited sensitivity and is optional. SPECT or SPECT/CT should be performed.

Management ▶ Given the results, the patient underwent esophagectomy with gastric pull-up. He has done well over several years of follow-up.

Further Readings Kim CK. Scintigraphic evaluation of the liver and biliary tract. In: Gazelle SG, et al., eds. Hepatobiliary and Pancreatic Radiology: Imaging and Interventions. New York: Thieme; 1998:108–153. Schillaci O, et al. Technetium-99m-labelled red blood cell imaging in the diagnosis of hepatic haemangiomas: the role of SPECT/CT with a hybrid camera. Eur J Nucl Med Mol Imaging. 2004;31(7):1011–1015.

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Case 171 History ▶ A 62-year-old woman with history of idiopathic thrombocytopenic purpura underwent a therapeutic splenectomy. Eight years later, she presented with recurrent thrombocytopenia. A nuclear medicine study was performed. A planar anterior view (left) and two selected SPECT views (right) are shown in Figure 171.1.

Figure 171.1 

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Case 171 Splenules

Figure 171.2  Radiopharmaceutical/Dose/Procedure: Damaged 99mTc-RBC/0.5 mCi/Selective spleen scan.

Findings ▶ Planar (left) and selected SPECT images (middle) showed two areas of uptake in the left abdomen, one in the anterior lateral abdomen near the level of the apex of the heart (Figure 171.2; dotted arrows), and a second in the posterior abdomen at the level of the upper pole of the left kidney (solid arrows).

Differential Diagnosis ▶ Splenules ▶ Polysplenia. Teaching Points ▶ Imaging for functional splenic tissue can be performed either with 99mTc-labeled damaged RBCs, as in the

present case or with 99mTc-sulfur colloid. ▶ Damaged RBCs are more rapidly sequestered in the spleen than undamaged cells. Autologous RBCs can be artificially damaged by heat, mechanical disruption, or with chemical agents such as N-ethylmaleimide. ▶ 99mTc-labeled damaged RBCs can be detected with a handheld gamma probe for intraoperative localization.

Management ▶ The patient underwent resection of the splenules. Further Readings Alvarez R, et al. Localization of splenosis using 99mTc-damaged red blood cell SPECT/CT and intraoperative gamma probe measurements. Eur J Nucl Med Mol Imaging. 2007;34(6):969. Armas RR. Clinical studies with spleen-specific radiolabeled agents. Semin Nucl Med. 1985;15(3):260–275.

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Case 172 History ▶ A 54-year-old woman with a history of carcinoma of the transverse colon, resected 4 years

previously, presented with multiple liver metastases. Since she was intolerant to chemotherapy, a different type of treatment was considered. Images shown in Figure 172.1 and Figure 172.2 were obtained using two different radiopharmaceuticals.

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Figure 172.2 

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Case 172 Hepatic Arterial Perfusion Scintigraphy With 99mTc-MAA and Yttrium-90 (90Y) Radioembolization of Metastatic Colon Cancer

Figure 172.3  Figure 172.4 

Figure 172.5 

Technique ▶ Figure 172.3: 99mTc-MAA/6.6 mCi injected into the proper hepatic artery. ▶ Figure 172.4: Bremsstrahlung scan obtained after selective radioembolization of the right hepatic lobe with 90Y-microspheres/28.7 mCi.

Findings ▶ Figure 172.3: ■ Heterogeneous liver activity, most intense at the site of the largest tumor seen on CT (Figure 172.5) ■ Faint thyroid activity (arrow) due to free pertechnetate ■ No significant pulmonary activity; lung/liver ratio = 2.8% ■ No significant collateral flow to stomach, intestine, or pancreas. ▶ Figure 172.4: ■ Tracer distribution in the right hepatic lobe similar to that with MAA. Differential Diagnosis ▶ Successful selective 90Y radioembolization ▶ Misplacement of catheter (if selective radioembolization was not intended). Teaching Points ▶ 90Y radioembolization is often performed to treat hepatocellular carcinoma and liver-only or liver-dominant metastatic disease from other cancers.

▶ Hepatic arterial injection of 99mTc-MAA before radioembolization. ■ Determines the degree of shunt to the lungs; a lung/liver ratio > 12% may preclude 90Y therapy due to the risk of radiation pneumonitis.

■ Determines possible collateral flow to abdominal organs (which often receive branches of the hepatic artery).

▶ SPECT/CT has been reported to show higher sensitivity for detecting abdominal collateral flow compared to

planar or SPECT images in 99mTc-MAA studies. ▶ High levels of free pertechnetate in 99mTc-MAA can lead to gastric activity that is difficult to distinguish from collateral flow to the stomach. The thyroid and salivary glands should be routinely imaged to check for free pertechnetate. ▶ 90Y: pure beta emitter. Post-radioembolization images are derived from Bremsstrahlung (“braking radiation”), given off as beta particles rapidly lose energy due to their interactions with tissue with “fuzzy” or “off-peak” image appearance.

Management ▶ Follow-up with FDG-PET/CT to assess therapy response. Further Readings Ahmadzadehfar H, et al. The significance of 99mTc-MAA SPECT/CT liver perfusion imaging in treatment planning for 90Y-microsphere selective internal radiation treatment. J Nucl Med. 2010;51(8):1206–1212. Sangro B, et al. Radioembolization for hepatocellular carcinoma: a review of the evidence and treatment recommnendations. Am J Clin Oncol. 2011;34(4):422–431.

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Case 173 History ▶ A 72-year-old man with metastatic colon cancer intolerant of chemotherapy presented for 90Y radioembolization of liver metastasis.

Coronal

Sagittal

Transaxial

MIP Coronal

Sagittal

Transaxial

Figure 173.1 

369

Case 173 Hepatic Arterial Perfusion Scintigraphy With 99mTc-MAA: Extrahepatic Gastrointestinal Perfusion Due to Incorrect Positioning of a Catheter Coronal

Sagittal

Transaxial

Coronal

Sagittal

Transaxial

MIP

Figure 173.2  Radiopharmaceutical/Dose/Procedure: 99mTc-MAA 6 mCi injected via selective arteriography.

Findings ▶ Extrahepatic activity along the falciform artery ▶ Hepatic perfusion confined to segment 4 ▶ No significant pulmonary activity. Differential Diagnosis ▶ Catheter dislodgement from left hepatic artery and into the falciform artery off the left hepartic artery. Teaching Points ▶ See Case 172. ▶ Be prepared for unexpected MAA distribution given variability of hepatic arterial anatomy and incidence of falciform artery.

▶ In this case, there was no significant uptake in the anterior abdominal wall. However, 90Y administration

through the falciform artery, a small terminal branch of the left or middle hepatic artery that runs through the falciform ligament to the anterior abdominal wall, can cause abdominal pain and radiation dermatitis. ▶ SPECT/CT or SPECT images fused with CT or MRI can more precisely localize MAA distribution than with planar images alone. ▶ If lung-to-liver ratio is abnormal, consider reducing 90Y dose.

Management ▶ A repeat study was performed after repositioning of the catheter. Further Readings Bhalani SM, et al. Radioembolization complicated by nontarget embolization to the falciform artery. Semin Intervent Radiol. 2011;28(2):234–239. Hoyer M, et al. Radiotherapy for liver metastases: a review of evidence. Int J Radiation Oncology Biol Phys. 2012;82(3):1047–1057. Kao YH, et al. Hepatic falciform ligament Tc-99m-macroaggregated albumin activity on SPECT/CT prior to Yttrium-90 microsphere radioembolization: prophylactic measures to prevent non-target microsphere localization via patent hepatic falciform arteries. Ann Nucl Med. 2011;25(5):365–369. Rosenbaum CENM, et al. Radioembolization for treatment of salvage patients with colorectal cancer liver metastases: a systematic review. J Nucl Med. 2013;54:1–6. DOI: 10.2967/jnumed.113.119545 Uliel L, et al. From the angio suite to the gamma-camera vascular mapping and 99mTc-MAA hepatic perfusion imaging before liver radioembolization—a comprehensive pictorial review. J Nucl Med. 2012; 53(11):1736–1747.

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Part 13

Gastrointestinal Tract Scott Britz-Cunningham, Hyewon Hyun, Chun K. Kim

Case 174 History ▶ A 46-year-old woman with postprandial bloating and discomfort (Figures 174.1 and 174.2). Anterior

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Case 174  Normal Gastric Emptying Anterior

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Radiopharmaceutical/Dose/Procedure: 99mTc-sulfur colloid in scrambled egg/0.3–0.5 mCi/Serial anterior and posterior views for 90 minutes.

Findings ▶ Normal lag phase of 12 minutes followed by linear emptying of gastric contents ▶ Normal T1/2 of 50 minutes ▶ 82% emptying by 90 minutes. Differential Diagnosis (Based on Clinical Presentation) ▶ Abnormal small or large bowel transit ▶ Celiac disease ▶ Chronic cholecystitis ▶ Dietary intolerance such as with lactose, fructose, gluten, etc. ▶ Functional dyspepsia ▶ Gastritis, including with H. pylori infection. ▶ Irritable bowel syndrome ▶ Small intestinal bacterial overgrowth. Teaching Points ▶ Rate of gastric emptying and the reference values are dependent on multiple factors, including size and contents of the meal, length of pre-test fasting, and time of day at which the scan is done.

▶ Solid meal empties with lag phase (10–20 minutes), followed by linear phase of continuous emptying with a slower phase much later.

▶ Liquid meal empties exponentially as function of volume. ▶ Normal T1/2 of clear liquids is 10–20 minutes. ▶ To take into account differential attenuation of radioactivity in the posterior (fundus) vs. anterior (antrum) portion of the stomach, anterior and posterior images are obtained to calculate geometric mean.

▶ Correct for radioactive decay; percent emptying will otherwise be overestimated. ▶ The best study to diagnose gastroparesis is radionuclide gastric emptying study. ▶ Recommendations for standardized gastric emptying study by the American Neuogastroenterology and

Motility Society and the Society of Nuclear Medicine together: ■ Imaging at 60, 120, 180, and 240 minutes. Residual gastric activity > 10% at 240 minutes is considered abnormal. Imaging may be terminated at any time point, if residual activity  90%) of crossed renal ectopia fuse. ▶ Both the anterior and posterior images are needed to obtain geometric mean counts for quantitative split-function measurements in these patients; note that this may still be affected by the vertebral attenuation.

Management ▶ Urologic consultation. Further Readings Applegate K, et al. Tc-99m DMSA imaging of crossed fused renal ectopia. Clin Nucl Med. 1995;20(10):947–948. Boyan N, et al. Crossed renal ectopia with fusion: report of two patients. Clin Anat. 2007;20(6):699–702.

398

Case 186 History ▶ A 40-year-old man in good health volunteered as a kidney donor. His preoperative serum creatinine was 0.97. A renal scan was performed to estimate the glomerular filtration rate. Images were obtained for 6 minutes (30 seconds/image) after radiotracer injection.

Figure 186.1  500

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Counts/Second

Case 186  Camera-Based GFR Measurement

Figure 186.3  Radiopharmaceutical/Dose/Procedure:

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Figure 186.4  99mTc-DTPA/10

mCi/GFR study.

Findings ▶ Figure 186.3: ■ Prompt renal uptake, split function 46% left, 54% right. ■ Collecting system visible between 2 and 3 minutes (5th and 6th frames) followed by ureters; 6-minute

period of imaging is too short to evaluate the later part of the excretory phase but sufficient for estimating the GFR. ■ Blood pool activity in the spleen and liver faintly visible for the first 2 minutes. ▶ Figure 186.4: ■ Renogram curves for 6-minute period ■ Peak activity: 2.5–3.0 minutes ■ Calculated raw GFR: 118.4 ml/min (total); 54.6 ml/min (left); 63.8 ml/min (right). ■ GFR corrected for body surface area: 96.6 ml/min/1.73 m2. Low-normal cutoff: 82 ml/min/1.73 m2 for age).

Differential Diagnosis ▶ Normal DTPA renogram for acquisition period. Teaching Points ▶ GFR can be measured using filtered radiotracers, including 99mTc-DTPA. 99mTc-MAG3 is primarily secreted and is useful for measuring effective renal plasma flow due to its high renal extraction.

▶ Advantages of camera-based GFR measurement over plasma methods: ■ Convenient (does not require collection of timed plasma or urine samples); split GFR measurement possible. ▶ Disadvantages: ■ Critically dependent on kidney depth, e.g., falsely increased depth estimation by 1 cm can lead to

underestimation of GFR by 14%; for 2 cm, as much as 26%; depth estimation could be more problematic for malrotated/ectopic/transplanted kidneys. ■ Results are invalid, i.e., underestimated, if dose is infiltrated. Injection site must be imaged. ■ Therefore, the camera method is less accurate than the plasma method. It is useful for general clinical indications but is not recommended for research purposes.

Management ▶ Donated left kidney without complication. Further Readings Gates GF. Split renal function testing using Tc-99m DTPA. A rapid technique for determining differential glomerular function. Clin Nucl Med. 1983;8(9):400–407. Tonnesen KH, et al. Influence on the renogram of variation in skin to kidney distance and the clinical importance thereof. In: Zum Winkel K, et al., eds. Radionuclides in Nephrology. Acton, MA: Publishing Sciences Group; 1975:79–86.

400

Case 187 History ▶ A 52-year-old female presented 1 week after renal transplant with minimal urinary output.

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401

Case 187  Acute Tubular Necrosis and Urine Leak

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Figure 187.4 

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Figure 187.5 

Radiopharmaceutical/Dose/Procedure: 99mTc-MAG3/10 mCi/Dynamic renogram; delayed image at 3 hours.

Findings ▶ Prompt uptake in the transplant kidney ▶ Continuously increasing cortical uptake throughout initial 25-minute dynamic imaging ▶ Markedly delayed excretion ▶ Extrarenal radiotracer activity superomedial and medial to the transplanted kidney corresponding to perinephric fluid on ultrasound

▶ Moderate excretion into the bladder Differential Diagnosis ▶ Differential for perinephric fluid collection after kidney transplantation: ■ Urinary leak (urinoma)—most likely given scan findings ■ Seroma; hematoma; lymphocele (weeks to months after the transplant) ▶ Differential for other scintigraphic findings: ■ Acute tubular necrosis—most likely given scan findings ■ Cyclosporine A toxicity; acute rejection. Teaching Points ▶ Preserved perfusion, continuously increasing radiotracer accumulation confined to cortex with little or no

accumulation in renal pelvis, typical of ATN (see also Case 184). ■ In acute rejection, perfusion and function are proportionately decreased. ▶ Urinary leaks occur from ureter (operative injury or rejection) or at the site of anastomosis. Management options include decompression (Foley placement, percutaneous nephrostomy stent) and surgical repair. ▶ Loculated urinoma may fill faintly, less intense than in the renal collecting system, due to dilution; delayed imaging and/or SPECT/CT maybe helpful. ▶ Other transplant complications: ■ Hyperacute rejection: Extremely rare ■ Chronic rejection: Decreased perfusion and uptake worsening over time; similar to cyclosporine A toxicity and recurrence of original renal disease; needs biopsy to differentiate ■ Infarct: Focal photopenia; may see rim of preserved activity ■ Renal artery stenosis: Assess with Captopril study ■ Urinary obstruction: Tracer in renal pelvis with slow radiotracer appearance in the bladder; furosemide study will demonstrate prolonged T1/2 clearance.

Management ▶ Treated with percutaneous drainage of the urinoma and retrograde stenting of the ureter with improvement of uninary output

▶ Treatment of ATN. Further Readings Maaloul M, et al. Diagnosis of urinoma complicating a renal graft using Tc99m-DTPA scintigraphy and factor analysis. Eur J Nucl Med Mol Imaging. 2005;32(7):854. Nicoletti R. Evaluation of renal transplant perfusion by functional imaging. Eur J Nucl Med. 1990;16(8–10):733–739.

402

Case 188 History ▶ A 26-year-old patient with hypertension had two renal scans on two separate days. Study 1

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Case 188 Hemodynamically Significant Left Renal Artery Stenosis (RAS) Study 1

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Figure 188.4 

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Figure 188.5 

Radiopharmaceutical/Dose/Procedure: 99mTc-MAG3/10 mCi/Baseline renal scan (Figure 188.4), Post-captopril (50 mg p.o.) scan (Figure 188.5).

Findings ▶ Faint visualization of the small right kidney on both studies ▶ Figure 188.4: Left renal uptake increases up to 6–9 minutes, then decreases. Bladder is not fully included

within the field of view. Top of bladder seen at 6–9 minutes as bladder fills. Blood pool clearance is delayed.

▶ Figure 188.5: Prolonged retention of left renal cortical uptake; minimal faint visualization of bladder on late frames.

▶ Figure 188.3: Marked difference in left renogram curves between the two studies. Differential Diagnosis ▶ Bilateral RAS (right, of long standing) ▶ Left RAS with atrophic right kidney due to other causes. Teaching Points ▶ Positive captopril renal scan indicates renovascular hypertension that will respond to angioplasty or surgical correction of RAS.

▶ RAS leads to decreased filtration pressure; renin-angiotensin-aldosterone cascade constricts efferent arterioles to maintain filtration; ACE inhibitor blocks this, eventually resulting in decreased filtration.

▶ Positive captopril study findings using 99mTc-DTPA vary significantly, depending on the magnitude of

captopril-induced renal decompensation (i.e., decreased GFR), whereas those with 99mTc-MAG3 are more straightforward, as in the following. ■ Increased cortical transit time. ▶ Delay in time to peak activity or no peak with continuously increasing activity throughout the study; renogram curve often similar to ATN ▶ In severe renal dysfunction, even with RAS, captopril studies are often non-diagnostic. ▶ Withhold ACE Inhibitors for 48–72 hours before study, diuretics for 24–48 hours. ▶ In the setting of hydronephrosis, may administer furosemide (1 mg/kg, max. 40 mg) just before or early in the study to minimize calyceal/pelvis activity.

Management ▶ Angioplasty of left renal artery with improvement in hypertension. Further Readings Dondi M, et al. Prognostic value of captopril renal scintigraphy in renovascular hypertension. J Nucl Med. 1992;33(11):2040–2044. Sfakianakis GN, et al. Single-dose captopril scintigraphy in the diagnosis of renovascular hypertension. J Nucl Med. 1987;28(9):1383–1392.

404

Part 15

Potpourri of Cases Chun K. Kim

Case 189 History ▶ A patient was found to have mild deviation of the trachea to the left and the question of retrosternal thyroid gland extension was raised. A thyroid scan was performed. Focal activity in the lower neck (arrow) is a radioactive marker placed at the suprasternal notch.

RAO

Anterior

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Figure 189.1 

407

Case 189  Parallax Error and Retrosternal Thyroid S

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Figure 189.2 

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Figure 189.3 

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Figure 189.4 

Radiopharmaceutical/Dose/Procedure: 123I-NaI/0.2 mCi/Pinhole imaging.

Findings ▶ Figure 189.2: Radioiodine uptake is seen inferior and slightly posterior to the right thyroid lobe (dotted arrows) but significantly above the level of the suprasternal notch (solid arrow).

▶ Figure 189.3 is a repeated image obtained with the pinhole aperture centered over the suprasternal notch, which shows the same structure just behind and slightly inferior to the suprasternal notch.

Differential Diagnosis ▶ None other than retrosternal thyroid tissue. Teaching Points ▶ In Figure 189.4(A), the pinhole collimator is centered over the thyroid gland (T), the typical position for

thyroid gland imaging. However, this positioning introduces a parallax error. As illustrated in Figure 189.4(A), the retrosternal thyroid tissue (RT) erroneously appears to be superior to the suprasternal notch (S) on the acquired pinhole image. ▶ The parallax error can be corrected by centering the pinhole collimator over the reference point (suprasternal notch in this case). Figure 189.3 was obtained as illustrated in Figure 189.4(B). ▶ Alternatively, a parallel-hole collimator or SPECT/CT may be performed to clarify the anatomic position. ▶ To evaluate a retrosternal thyroid gland, 131I is recommended by some authors because the high-energy photons (364-keV) are less attenuated by overlying sternum than 123I photons (159-keV). However, 123I provides overall superior image quality because of its optimal photon energy for gamma imaging and lower radiation, resulting in higher administered dose, when compared to 131I. Therefore, 123I is generally sufficient for this purpose, as illustrated by this case. 99mTc-pertechnetate is not recommended because of high blood pool activity in the retrosternal region and low thyroid-to-background ratio.

Management ▶ Surgery is considered the treatment of choice for a retrosternal goiter. Further Reading McKitrick WL, et al. Parallax error in pinhole thyroid scintigraphy: a critical consideration in the evaluation of substernal goiters. J Nucl Med. 1985;26(4):418–420.

408

Case 190 History 111In-WBC

scan was performed to localize the source of bacteremia. Anterior and posterior whole body images are shown in Figure 190.1.

Figure 190.1 

409

Case 190  Recent Radioiodine Therapy for Graves Disease

Figure 190.2  Radiopharmaceutical/Dose/Procedure: 111In-WBC/0.5 mCi/Imaging 24 hours after injection.

Findings ▶ Except for the lower extremities, the body is obscured by intense radioactivity. ▶ Tracer uptake in the femora and the region of the tibial plateau represents mild bone marrow expansion. ■ Normally, active hematopoietic bone marrow is limited to the axial skeleton, proximal humeri, and femora

in adults. However, bone marrow expands more distally in anemic patients associated with various diseases.

Differential Diagnosis and Teaching Points ▶ Radioactivity contamination: Unlikely, given the extent and intensity of radiotracer activity that obscures the body.

▶ This patient received 15 mCi 131I therapy for Graves disease a few days before this scan. The radioactivity

obscuring the body resulted from the large administered 131I dose (15 mCi) compared to 0.5 mCi of 111In, high retention of 131I in the thyroid gland, 8-day half-life, and high-energy (364 keV) gamma photons penetrating the septa of the medium energy collimator used for 111In imaging. ■ The images shown in Figure 190.1 are analog or film based and used to be reviewed on a viewbox before the era of “digital” images viewed on computers. On digital images, decreasing the intensity would show focal activity in the thyroid bed, and would decrease the visibility of structures with 111In-WBC uptake (i.e., liver, spleen, and bone marrow).

Management ▶ Obtain history of prior radionuclide administration. ▶ Interpret the study as non-diagnostic.

410

Case 191 History ▶ A 42-year-old woman had a 99mTc-labeled red blood cell GI bleeding scan. The first set of serial dynamic images (~ 30 minutes) is shown in Figure 191.1.

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Figure 191.1 

411

Case 191  Attenuation of Gamma Photons by Barium

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Figure 191.2  Radiopharmaceutical/Dose/Procedure: 99mTc-RBC/20 mCi/Dynamic anterior imaging of the abdomen.

Findings, Differential Diagnosis, and Teaching Points ▶ Finding 1: Photopenic defect conforming to the ascending and transverse colon ■ The photopenic defect was due to colonic barium. High-density contrast material can attenuate gamma

photons and obscure GI bleeding. Barium accumulated in one area may cause a defect simulating a mass. For example, barium within the rectum may appear as a defect in the urinary bladder on the posterior view of a bone or renal scan). Images taken in other projections may be helpful. ■ Air in bowel alone does not attenuate photons. Distended bowel filled with fluid or feces may appear photopenic to some degree but usually not as photopenic as shown in Figure 191.1. ▶ Finding 2: Oval-shaped increased activity (arrowhead) ■ Uterus vs. uterine fibroid vs. other pelvic mass—correlation with menstrual cycle and/or pelvic ultrasound may be needed. ■ This is not due to GI bleeding as activity is present on the first frame and unchanged throughout the study. ▶ Finding 3: Gradually increasing activity in the epigastric region (Figure 191.2; white arrows) ■ Free pertechnetate vs. gastric bleeding vs. gastritis. If bleeding, activity is expected to move. If gastritis, increased blood pool activity would be present from the beginning, without any significant change over time. Free pertechnetate would be most likely, given that activity gradually increases and does not move similar to bladder activity (see Finding 4). ▶ Finding 4: Tracer accumulation in the lower pelvis (black arrows) ■ Excreted activity in the urinary bladder vs. bleeding in the lower pelvis. Additional dynamic images demonstrating no movement or images in different projection assessing more detailed location (anterior vs. posterior) may be helpful. ▶ Finding 5: Splenomegaly, consistent with the history of leukemia.

Management ▶ The patient was found to have infectious colitis and was treated accordingly.

412

Case 192 History ▶ Shortness of breath; rule out pulmonary embolism. Ventilation images (top 2 rows) were obtained

following inhalation of 99mTc-DTPA aerosol. Subsequently, the patient was injected with 99mTc-MAA, and perfusion images (bottom 2 rows) were obtained. The study was performed using a dual-head gamma camera, i.e., anterior, RAO, right lateral, and RPO views with Head-1, and posterior, LPO, left lateral, and LAO views with Head-2.

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Case 192 Photopeak Energy Setting of Camera Head-2 Drifted During Imaging Anterior

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Findings ▶ Figure 192.2: Ventilation and perfusion images obtained using Camera Head-2 (Row 2 and 4) are not as sharp as those obtained using Head-1 (Row 1 and 3). Further, the image quality in Rows 2 and 4 deteriorates from left to right. ▶ Figure 192.3: Left lateral and LAO perfusion images repeated using Head-1 (bottom row) show a sharp wedge-shaped defect involving the inferior lingular segment, as well as increased tracer activity in the kidneys consistent with interim pulmonary absorption of DTPA aerosol into the blood, followed by renal excretion.

Differential Diagnosis ▶ Low resolution due to increased distance between the patient and Head-2 (often below the imaging table). Teaching Points ▶ An incorrect photopeak energy setting can degrade image uniformity, reduce sensitivity, and increase scatter. ■ Photopeak variation may result from voltage or temperature changes or photomultiplier drift, among other factors.

■ A sudden change in the photopeak setting should be fully investigated. ■ If a change in the camera photopeak setting is discovered, the settings for other radionuclides need to be verified.

▶ A common cause (arguably the most common cause) of low-resolution images obtained with parallel-hole collimation is positioning the camera too far away from the patient. The farther the camera, the worse the image resolution. This typically results in blurring of structure margins but does not increase the number of scattered photons. In Figure 192.2 and the upper panel of Figure 192.3, notice the increased number of scattered photons in the soft tissue around the lungs.

Management ▶ Gamma camera quality control was performed, including a full investigation of the problem. Further Reading Minimum quality control requirements for nuclear medicine equipment. http://www.anzsnm.org.au/cms/assets/Uploads/ Documents/Committees/Technical-Standards/Minimum_QC_Tests_5_7.pdf (accessed on October 5, 2014).

414

Case 193 History None. What is the radiopharmaceutical? What is the cause of the artifact seen in the images in Figure 193.1?

Figure 193.1 

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Case 193 Photomultiplier Tube Artifact Due to an Incorrect Photopeak Energy Setting

Figure 193.2  Radiopharmaceutical/Dose/Procedure: 111In-pentetreotide/5 mCi/imaging 24 hours after injection.

Findings ▶ Multiple photopenic defects ▶ Overall poor image resolution. Differential Diagnosis ▶ None Teaching Points ▶ Setting the photopeak energy in the region of the upper edge of the primary energy photopeak (higher photon energy range) can result in relative photopenic defects over the photomultiplier (PM) tubes. Conversely, setting the photopeak energy window in the region of the lower edge of the primary energy photopeak (lower photon energy range) can result in relative “hot spots” over the PM tubes. ▶ This effect may be potentiated when the PM tube gain has been adjusted to optimize image acquisition using another radionuclide.

Management ▶ Quality control of the gamma camera was performed. Further Reading Early PJ. Chapter 13. Planar imaging. In: Early PJ, Sodee DB, eds. Principles and Practice of Nuclear Medicine. 2nd ed. St. Louis: Mosby-Year Book; 1995:251–290.

416

Case 194 History ▶ A patient with a history of thrombocytopenic purpura and splenectomy was referred to nuclear medicine for evaluation of an accessory spleen. A 99mTc-sulfur colloid scan was performed.

May 6th

Figure 194.1 

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Case 194 False-Negative Sulfur Colloid Scan for an Accessory Spleen Due to Suboptimal Intensity Setting

May 8th

May 6th

Figure 194.2 

Figure 194.3 

May 6th

Figure 194.4 

Radiopharmaceutical/Dose/Procedure ▶ Figures 194.2 and 194.4: 99mTc-sulfur colloid/5 mCi/static imaging in multiple projections beginning 15 minutes after injection.

▶ Figure 194.3: Heat-damaged 99mTc-RBC/5 mCi/static imaging in multiple projections, beginning at 60 minutes after injection.

Findings ▶ Figure 194.2: Normal uptake in the liver and bone marrow. The scan was read as “no evidence of an accessory spleen.” Note that the image intensity setting is optimized for a typical liver/spleen scan.

▶ Figure 194.3: Heat-damaged RBC scan performed two days later showed focally increased uptake in the left upper quadrant, consistent with an accessory spleen.

▶ Figure 194.4: Retrospective review of the original 99mTc-sulfur colloid images displayed with a different intensity setting clearly show the accessory spleen.

Differential Diagnosis ▶ None. Teaching Points ▶ See Case 171. ▶ Sulfur colloid uptake by splenic tissue is lower than uptake of damaged RBCs. Nonetheless, appropriately

adjusting the image intensity setting can improve detection of an accessory spleen on a sulfur colloid scans. If the result on planar imaging is negative or indeterminate, SPECT (or SPECT/CT if available) is strongly recommended.

Management ▶ Surgical resection. Further Readings Alvarez R, Diehl KM, Avram A, Brown R. Piert M. Localization of splenosis using 99mTc-damaged red blood cell SPECT/CT and intraoperative gamma probe measurements. Eur J Nucl Med Mol Imaging. 2007;34(6):969. Armas RR. Clinical studies with spleen-specific radiolabeled agents. Semin Nucl Med. 1985;15(3):260–275.

418

Appendix

Table A.1  Physical Properties of Radionuclides Radionuclides

Physical T1/2

Type of Decay (Emitted γ or X-Ray Energy)

11C

(carbon-11)

20 m

β+ (γ 511 keV)

13N

(nitrogen-13)

10 m

β+ (γ 511 keV)

15O

(oxygen-15)

2m

β+ (γ 511 keV)

18F

(fluorine-18)

110 m

β+ (γ 511 keV)

32P

(phosphorus-32)

14.3 d

β−

57Co

(cobalt-57)

271 d

EC (γ 122 keV)

67Ga

(gallium-67)

78 h

EC (γ 93, 185, 300, 394 keV)

13 s

IT (γ 191 keV)

(rubidium-82)

1.3 m

EC β+ (γ 511 keV)

89Sr

(strontium-89)

50.5 d

β−

90Y

(yttrium-90)

64 h

β−

81mKr 82Rb

(krypton-81m)

99Mo

(molybdenum-99)

66 h

β−

99mTc

(technetium-99m)

6h

IT (γ 140 keV)

(indium-111)

2.8 d

EC (γ 171, 245 keV)

111In 123I

(iodine-123)

13.2 h

EC (γ 159 keV)

124I

(iodine-124)

4.2 d

EC (numerous γ) β+ (γ 511 keV)

125I

(iodine-125)

60 d

EC (γ 35 keV and numerous X-ray 27–32 keV)

131I

(iodine-131)

8d

β− (γ 364 keV)

(xenon-133)

5.2 d

β− (γ 81 keV)

(samarium-153)

46.7 h

β− (γ 103 keV)

201Th

(thallium-201)

73 h

EC (γ 135, 157 keV) (mercury X-rays 69–80 keV)

223Ra

(radium-223)

11.4 d

α

133Xe 153Sm

β− and α energies are not listed. γ emissions not used for imaging or gamma counting (either because of too high an energy or paucity of emissions) are not listed. T1/2 = half-life; keV = kiloelectron volt; IT = isomeric transition; EC = electron capture; s = seconds; m = minutes; h = hours; d = days.

419

Index of Cases

Part 1. Nuclear CNS Imaging 1. Left Temporal Interictal Seizure Focus 2. Brain Death 3. Left ACA Stroke and MCA Ischemia 4. Alzheimer Disease 5. Frontotemporal Dementia 6. Dementia with Lewy Bodies 7. Crossed Cerebellar Diaschisis Due to Chronic Infarct 8. Radionuclide Cisternogram: Normal Pressure Hydrocephalus 9. Normal Ventriculoperitoneal Shunt Flow 10. Recurrent Malignancy

Part 2. Nuclear Inflammation/Infection Imaging 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

22. 23. 24. 25. 26. 27. 28.

Interstitial Nephritis Spinal Osteomyelitis with Adjacent Psoas Abscess Sarcoidosis Pneumocystis Carinii (Jiroveci) Pneumonia Pseudomembranous Colitis Spinal Osteomyelitis Femoral-Popliteal Prosthetic Vascular Graft Infection Normal Physiological Pulmonary Uptake of Labeled Leukocytes on Early Images Localized Bone Marrow Expansion Osteomyelitis Involving a Neuropathic Joint Infected Right Total Knee Replacement and Hypercellular Bone Marrow Around the Left Total Knee Replacement Abdominal Abscess Physiologic Uptake Around Entry Site of a Feeding Gastrostomy Sarcoidosis Infected Abdominal Aortic Endograft Spinal Osteomyelitis/Infected Hardware Fever of Unknown Origin/Non-Hodgkin Lymphoma Infected Right Total Hip Replacement

Part 3. Ventilation/Perfusion Lung Scintigraphy 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41.

Normal Ventilation (133Xe) and Perfusion Pulmonary Embolism Chronic Obstructive Pulmonary Disease Chronic Obstructive Pulmonary Disease Stripe Sign Pseudo-Stripe Sign; Single V/Q Mismatch on SPECT Triple Match (V/Q Match With Radiographic Abnormality) Reverse V/Q Mismatch Shunting of Perfusion Through Atelectatic Lower Lobes Due to PEEP Unilateral V/Q mismatch Due to Centrally Located Tumor Pulmonary Embolism Attenuation Artifact Due to Arms Hot Spots Due to Clumping of MAA Particles

Part 4. Pediatric Nuclear Medicine 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57.

Biliary Atresia Choledochal Cyst (Type I) Ectopic Gastric Mucosa in a Meckel Diverticulum Tracheobronchial Aspiration Non-Obstructive Hydronephrosis Multicystic Dysplastic Kidney Vesicoureteral Reflux (RNC-Grade 3) Lingual Thyroid Non-Accidental Trauma (Child Abuse) Ischiopubic Synchondrosis Polyostotic Fibrous Dysplasia Osteoid Osteoma Osteomyelitis Perthes Disease Neuroblastoma Left Pulmonary Artery Atresia (Previously Treated) With a Right-to-Left Cardiac Shunt

421

58. Bilateral Pars Stress in Vertebra L4 With Spondylolysis Confirmed on CT 59. Stress Fracture

Part 5. Nuclear Cardiac Imaging 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73.

Reporting of Exercise Myocardial Perfusion Imaging Normal Pharmacological Stress MPI Abnormal Exercise MPI Infarction in the Obtuse Marginal and Posterior Descending ArteryTerritory Mild Ischemia in the LAD Territory With Transient Ischemic Dilatation Hibernating Viable Myocardium in the LAD Territory Cardiac Sarcoid Incorrectly Placed Background Activity Overlapping With Spleen Normal Study—Breast Attenuation Artifact Fixed Septal Perfusion Defect Due to Left Bundle Branch Block Motion Artifact (Hurricane Sign) Non-Ischemic Dilated Cardiomyopathy Doxorubicin Cardiotoxicity—Decreased Left Ventricle Function Diaphragmatic Attenuation Artifact

Part 6. Bone Scintigraphy 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90.

Paget Disease Paget Disease and Metastatic Prostate Cancer Flare Phenomenon Bone Tracer Uptake in Cerebral Infarct Heterotopic Ossification Hypertrophic Osteoarthropathy Metastatic Calcification/Renal Osteodystrophy Dystrophic Calcification—Mucinous Colon Metastatic Cancer Superscan Os Trigonum Syndrome Plantar Fasciitis and Metatarsal Stress Fracture Acute and Chronic Compression Fractures Sacral Insufficiency Fracture/Multiple Rib Fractures Shin Splint and Stress Fracture Complex Regional Pain Syndrome Osteomyelitis and Cellulitis Added Value of SPECT/CT in Metastatic Survey Bone Scan

Part 7. PET/CT in Oncology: I 91. 18F-FDG-PET/CT Procedure and Physiologic Distribution 92. Altered 18F-FDG Biodistribution With Diffuse Increased Uptake in Skeletal Muscle Due to Eating Right Before Scan

422

Index of Cases

93. Polymyositis (Statin-Associated) 94. Melanoma 95. Nasopharyngeal Cancer 96. Recurrent Lung Cancer 97. Incidental Thyroid Nodule 98. Hashmoto Thyroiditis (Incidentally Noted) 99. Metabolically Active Brown Adipose Tissue 100. Lung Cancer (FDG-Avid Solitary Pulmonary Nodule) 101. Adenocarcinoma in Situ 102. Pulmonary Hamartoma (FDG-Avid Pulmonary Nodule [False Positive]) 103. Lung Cancer Initial Staging (TNM Staging System) 104. Lung Cancer Initial Staging (Distant Metastases) 105. Radiation Pneumonitis 106. Pleural Talc Crystal Deposits From Pleurodesis 107. Thymic Rebound 108. Post-Therapy Lymphoma 109. Sarcoidosis 110. Lipomatous Hypertrophy of the Interatrial Septum 111. Breast Cancer With Incidental Pneumonia 112. Metabolically Active Glandular Tissue in a Lactating Patient Who Is Breastfeeding

Part 8. PET/CT in Oncology: II 113. Esophageal Cancer 114. Physiologic Gastric Uptake and Recurrent Gastric Carcinoma 115. Attenuation Artifact Due to Patient Motion 116. Metastatic Sigmoid Colon Cancer With a Synchronous Colon Cancer 117. Colon Cancer (Unknown Primary) 118. Incidental Adrenal Adenoma 119. Incidental Renal Cell Carcinoma 120. Metastatic Cervical Cancer (Stage IVB) 121. Metabolically Active Corpus Luteum Cyst in the Right Ovary 122. Physiologic Uptake in Fallopian Tubes and Endometrium 123. Ovarian Cancer and Rising CA-125 124. Synovial Sarcoma 125. Multiple Myeloma 126. Undescended Testis and Metformin-Associated Colonic Uptake 127. Lymphoma Staging 128. Inflammatory/Reactive Lymph Nodes Due to Flu Shot 129. Effects of Hematopoietic Stimulating Factors 130. Attenuation Artifact (Metallic Objects)

Part 9. General Oncologic Imaging 131. Carcinoid Tumor

132. 133. 134. 135.

Pheochromocytoma Identify the Radiopharmaceutical Breast Lymphoscintigraphy Melanoma Lymphoscintigraphy/Sentinel Lymph Node Mapping 1 36. Lymphedema

Part 10. Thyroid and Parathyroid 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. 148. 149. 150. 151. 152.

Hyperthyroidism, Graves Disease Hyperthyroidism, Subacute Thyroiditis Hyperthyroidism, Graves Disease Autonomous (“Hot”) Thyroid Nodule Graves Disease Versus Toxic Nodular Disease Nonfunctional (“Cold”) Thyroid Nodule Neonatal Hypothyroidism With an Ectopic Thyroid Gland Thyroid Hormone Metabolism in the Liver/ Radioiodine Uptake in Tooth Filling Pre-Treatment 123I Scan and Post-Therapy 131I Scan in a Patient With Thyroid Cancer Papillary Thyroid Cancer; Progressive Lung Metastases with Decreasing Iodine Avidity Parathyroid Adenoma: Single-Isotope Dual-Phase Technique Parathyroid Adenoma: Dual-Isotope Technique Parathyroid Carcinoma Secondary Hyperparathyroidism, Parathyroid Hyperplasia Ectopic Parathyroid Adenoma Parathyroid Adenoma/Thymoma (Mixed Type)

Part 11. Radionuclide Therapy and Pre-Therapy Evaluation 153. 131I Therapy of Hyperthyroidism 154. 131I Therapy of Differentiated Thyroid Cancer 155. Peritoneal Scintigraphy Before Intraperitoneal 32P Instillation 156. 123I-MIBG Scans Before and After 131I-MIBG Therapy of Neuroblastoma 157. Samarium Therapy for Bone Pain Palliation 158. Radium-223 Dichloride Therapy for Bone Metastases 159. Radioimmunotherapy-1 160. Biodistribution of Ibritumomab Tiuxetan (Zevalin®) 161. Biodistribution of Tositumomab (Bexxar®)

Part 12. Liver, Spleen, and Biliary Tract 162. Morphine Augmentation 163. Importance of CCK Infusion Rate for Measurement of Gallbladder Ejection Fraction

164. 165. 166. 167. 168. 169. 170. 171. 172.

Normal Variant: Preferential Gallbladder Filling Acute Acalculous Cholecystitis With Rim Sign Right Portal Vein Thrombosis Bile Leak Intrahepatic Cholestasis Focal Nodular Hyperplasia Hepatic Hemangioma Splenules Hepatic Arterial Perfusion Scintigraphy with 99mTc-MAA and Yttrium-90 (90Y) Radioembolization of Metastatic Colon Cancer 1 73. Hepatic Arterial Perfusion Scintigraphy with 99mTc-MAA: Extrahepatic Gastrointestinal Perfusion Due to Incorrect Positioning of a Catheter

Part 13. Gastrointestinal Tract 174. 175. 176. 177. 178. 179. 180. 181.

Normal Gastric Emptying Gastroparesis Rapid Gastric Emptying Tracheobronchial Aspiration Ectopic Gastric Mucosa Acute Large Bowel Bleeding Acute Intraperitoneal Bleeding False Positive GI Bleeding Study, Complicated by Free Pertechnetate

Part 14. Renal Scintigraphy 182. Normal Renal Scan 183. Urinary Tract Obstruction at the Ureteropelvic Junction 184. Acute Tubular Necrosis 185. Cross-Fused Pelvic Kidneys 186. Camera-Based GFR Measurement 187. Acute Tubular Necrosis and Urine Leak 188. Hemodynamically Significant Left Renal Artery Stenosis

Part 15. Potpourri of Cases 189. 190. 191. 192.

Parallax Error and Retrosternal Thyroid Recent Radioiodine Therapy for Graves Disease Attenuation of Gamma Photons by Barium Photopeak Energy Setting of Camera Head-2 Drifted During Imaging 193. Photomultiplier Tube Artifact Due to an Incorrect Photopeak Energy Setting 1 94. False-Negative Sulfur Colloid Scan for an Accessory Spleen Due to Suboptimal Intensity Setting

Index of Cases

423

Index

18F-FDG

PET or PET/CT Alzheimer disease, 9–10 brain tumor, recurrent, 21–22 crossed cerebellar diaschisis, 15–16 dementia with Lewy bodies, 13–14 epilepsy, temporal lobe, 3–4 graft infection, abdominal aortic, 53–54 hibernating viable myocardium, 139–140 imaging protocol, 195–196 oncology, 195–276 ( See also Oncology, 18F-FDG PET-CT) physiologic distribution, 195–196 sarcoidosis, cardiac, 141–142 sarcoidosis, intrathoracic 51–52 skeletal muscle uptake, eating before scan, 197–198 spinal osteomyelitis, infected hardware, 55–56 18F-sodium fluoride bone PET, child abuse, 107–108 32P therapy bone pain palliation, 336 intraperitoneal, peritoneal scintigraphy before, 331–332 67Ga-citrate interstitial nephritis, 25–26 distribution, 283–284 P. carinii pneumonia, 31–32 spinal osteomyelitis, psoas abscess, 27–28 81mKr ventilation imaging, atelectasis, ineffective PEEP, 79–80 82Rb myocardial perfusion imaging cardiac sarcoid, 141–142 hibernating viable myocardium, 139–140 ischemia, LAD, transient ischemic dilatation, 137–138

obtuse marginal and posterior descending artery infarction, 135–136 89Sr-chloride therapy, bone pain palliation, 336 90Y-ibritumomab tiuxetan + rituximab, non-Hodgkin lymphoma, 340 90Y yttrium radioembolization, metastatic colon cancer, with hepatic arterial perfusion scintigraphy, 367–368 99mTc-disofenin (DISIDA) cholescintigraphy CCK infusion rate, gallbladder ejection fraction, 347–348 CCK pretreatment, preferential gallbladder filling, 347–348 cholecystitis, acute acalculous, rim sign, 347–348 99mTc-DMSA renal cortical scintigraphy multicystic dysplastic kidney, 101–102 renal function assessment, 100 99mTc-DTPA brain death, 6 breastfeeding, 84 GFR measurement, camera-based, 399–400 99mTc-DTPA aerosol ventilation imaging chronic obstructive pulmonary disease, 67–68, 69–70 pulmonary embolism, 65–66 stripe sign, 71–72 stripe sign, pseudo-, 73–74 triple match, 75–76 V/Q mismatch, reverse, 77–78 99mTc-ECD brain death, 6 left ACA stroke and MCA ischemia, 7–8 99mTc-HMPAO brain death, 5–6 frontotemporal dementia, 11–12

425

99mTc-HMPAO-WBC, 99mTc-leukocyte

normal, 283–284 imaging, pseudomembranous

colitis, 34 aerosol ventilation imaging, V/Q mismatch pulmonary embolism, 83–84 unilateral, centrally located tumor, 81–82 99mTc-MAA hepatic arterial perfusion scintigraphy 90Y yttrium radioembolization of metastatic colon cancer, 367–368 extrahepatic GI perfusion, catheter positioning, 369–370 99mTc-MAA, left pulmonary artery atresia, right-to-left cardiac shunt, 121–122 99mTc-MAA perfusion imaging atelectasis, ineffective PEEP, 79–80 attenuation artifact, arms, 85–86 breastfeeding, 84 chronic obstructive pulmonary disease, 67–68 hepatic arterial, 367–368 hot spots, MAA particle clumping, 87–88 lung, normal, 63–64 pulmonary embolism, 65–66 triple match, 75–76 V/Q mismatch, pulmonary embolism, 83–84 V/Q mismatch, reverse, 77–78 V/Q mismatch, unilateral, centrally located tumor, 81–82 99mTc-MAG3, 392 99mTc-MAG3 renal scan acute tubular necrosis, 395–396 acute tubular necrosis, urine leak, 401–402 cross-fused pelvic kidneys, 397–398 left renal artery stenosis, 403–404 non-obstructive hydronephrosis, diuretic, 99–100 normal renal scan, 391–392 split function assessment, 391–392 urinary tract obstruction, ureteropelvic junction, 393–394 99mTc-MDP bone scan ischiopubic synchondrosis, 109–110 osteomyelitis, 115–116 Perthes disease, three-phase scan, 117–118 polyostotic fibrous dysplasia, 111–112 total hip replacement, infected right, 59–60 99mTc-MDP bone scan with SPECT L4 bilateral pars stress, spondylolysis, 123–124 osteoid osteoma, 113–114 stress fracture, three-phase scan, 125–126 99mTc-mebrofenin cholescintigraphy bile leak, 357–358 99mTc-DTPA

426

Index

biliary atresia, 85–86 choledochal cysts, 93–94 cholestasis, intrahepatic, 359–360 focal nodular hyperplasia, 361–362 morphine augmentation, 347–348 portal vein thrombosis, right, 355–356 99mTc-RBC bleeding scan ectopic gastric mucosa, 381–382 false positive GI, free pertechnetate, 387–388 gamma photon attenuation, barium, 411–412 intraperitoneal bleeding, acute, 385–386 large bowel bleeding, acute, 383–384 99mTc-RBC, heat-damaged splenules, 365–366 suboptimal intensity setting, 418 99mTc-RBC ventriculogram incorrectly background ROI overlapping spleen, 143–144 LV function decreased, doxorubicin cardiotoxicity, 153–154 99mTc-sestamibi myocardial perfusion imaging attenuation artifact, diaphragmatic, 155–156 breast attenuation artifact, 145–146 dilated cardiomyopathy, non-ischemic, 151–152 exercise, reporting, 129–130 left bundle branch block, fixed septal perfusion defect, 147–148 motion artifact, hurricane sign, 149–150 pharmacological stress, normal, 131–132 99mTc-sestamibi parathyroid scintigraphy hyperparathyroidism, secondary, parathyroid hyperplasia, 319–320 parathyroid adenoma, dual-isotope technique, 315–316 parathyroid adenoma, ectopic, 321–322 parathyroid adenoma, single-isotope dual-phase technique, 313–314 parathyroid adenoma/thymoma (mixed type), 323–324 parathyroid carcinoma, 317–318 99mTc-sodium pertechnetate direct radionuclide cystogram, vesicoureteral reflux, 103–104 99mTc-sodium pertechnetate Meckel scan ectopic gastric mucosa, 381–382 ectopic gastric mucosa, Meckel diverticula, 95–96 99mTc-sodium pertechnetate thyroid scan, Graves disease vs. toxic multinodular goiter, 301–302 99mTc-sulfur colloid bone marrow imaging bone marrow expansion, localized, 41–42 osteomyelitis, diagnosis, 41–42 osteomyelitis, neuropathic joint, 43–44

total knee replacement infection, hypercellular bone marrow, 45–46 99mTc-sulfur colloid scan false-negative, suboptimal intensity setting, 417–418 hemangioma, hepatic hemangioma, 363–364 hepatobiliary scintigraphy, focal nodular hyperplasia, 361–362 lymphoscintigraphy, lymphedema, 289–290 lymphoscintigraphy/sentinel lymph node mapping, breast cancer, 285–286 lymphoscintigraphy/sentinel lymph node mapping, melanoma, 287–288 tracheobronchial aspiration, salivagram, 97–98 99mTc-sulfur colloid, scrambled egg gastric emptying, normal, 373–374 gastric emptying, rapid, 377–378 gastroparesis, 375–376 tracheobronchial aspiration, 379–380 111In-DTPA CSF injection, 18 normal pressure hydrocephalus, radionuclide cisternogram, 17–18 ventriculoperitoneal shunt flow, normal, 19–20 111In-ibritumomab tiuxetan, biodistribution, 341–342 111In-labeled leukocytes abdominal abscess, 43–44 bone marrow expansion, localized, 41–42 feeding gastrostomy entry site, physiologic uptake, 49–50 femoral-popliteal prosthetic vascular graft infection, 37–38 normal, 283–284 normal physiological pulmonary uptake, early images, 39–40 pseudomembranous colitis, 33–34 spinal osteomyelitis, 35–36 111In-labeled leukocytes + 99mTc-sulfur colloid osteomyelitis, diagnosis, 41–42 osteomyelitis, neuropathic joint, 43–44 total knee replacement infection, hypercellular bone marrow, 45–46 111In-pentetreotide, 280 carcinoid tumor, 279–280 normal, 283–284 123I-Ioflupane (DaTscan) SPECT, dementia with Lewy bodies, 14 123I-meta-iodobenzylguanine (123I-MIBG) scans, 120 before and after 131I-MIBG therapy, neuroblastoma, 333–334 normal, 283–284 pheochromocytoma, 281–282

123I-meta-iodobenzylguanine (123I-MIBG)

therapy, neuroblastoma, 333–334 123I-NaI (sodium iodide) thyroid scan applications, 120 Graves disease vs. toxic multinodular goiter, 301–302 hyperparathyroidism, secondary, with parathyroid hyperplasia, 319–320 hyperthyroidism, Graves disease, 293–294, 297–298 hyperthyroidism, subacute thyroiditis, 295–296 hypothyroidism, neonatal, ectopic thyroid gland, 305–306 lingual thyroid, 105–106 neuroblastoma, 119–120 parallex error and retrosternal thyroid, 407–408 parathyroid adenoma, dual-isotope technique, 315–316 thyroid cancer, pre-treatment, 303–304 thyroid nodule, autonomous (“hot”), 299–300, 327–328 thyroid nodule, nonfunctional (“cold”), 303–304 131I-NaI (sodium iodide) thyroid scan thyroid hormone liver metabolism, 307–308 tooth filling uptake, 303–304 131I therapy differentiated thyroid cancer, 329–330 hyperthyroidism (Graves disease), 294, 298, 302, 327–328 recent 131I therapy causing septal penetration, 409–410 thyroid cancer, metastatic differentiated, 312 thyroid nodule, autonomous (“hot”), 299–300, 327–328 toxic multinodular goiter, 294, 298, 302 131I, thyroid cancer, post-therapy, 303–304 131I-tositumomab, biodistribution, 343–344 131I-tositumomab + tositumomab, non-Hodgkin lymphoma, 340 133Xe attenuation artifact, arms, 85–86 breastfeeding, 84 hepatic steatosis, 70 133Xe ventilation imaging chronic obstructive pulmonary disease, 69–70 normal, 63–64 153Sm-EDTMP therapy, bone pain palliation, 336 201Tl-chloride brain malignancy, recurrent, 21–22 brain uptake, 22 normal, 283–284 223Ra-dichloride bone scan, bone metastases, 337–338

Index

427

223Ra-dichloride

therapy bone metastases, 337–338 bone pain palliation, 336

Abdominal abscess, 47–48 Abdominal aortic aneurysm, 47–48 Abdominal aortic endograft infection, 53–54 Abscess abdominal, 47–48 psoas, 27–28 Acetazolamide, 8 Acute interstitial nephritis, 25–26 Acute tubular necrosis, 26, 395–396 urine leak, 401–402 Adenocarcinoma in situ, lung, 215–216 Adenoma adrenal, incidental, 251–252 hepatic, 362 Adenoma, parathyroid dual-isotope technique, 315–316 ectopic, 321–322 single-isotope dual-phase technique, 313–314 with thymoma (mixed type), 323–324 Adenopathy, FDG-avid, 204 Adenosine, pharmacological stress MPI, 131–132 Adipose tissue, metabolically active brown, 211–212 Adrenal adenoma, incidental, 251–252 Adrenal gland, lung cancer metastases, 221–222 Airspace disease diffuse, 68 stripe sign, 71–72 Air trapping, 70 Alzheimer disease, 9–10 Amoxicillin, pseudomembranous colitis, 33–34 Anterior cerebral artery stroke, left, 7–8 Arms, attenuation artifact, 85–86 Artifacts attenuation (See Attenuation artifacts) photomultiplier tube, photopeak energy setting, 415–416 septal penetration of high-energy photons, 409–410 Aspiration, tracheobronchial, 379–380 Atelectasis lower-lobe perfusion shunting, PEEP, 79–80 reverse V/Q mismatch, 80 Attenuation artifacts arms, 85–86 breast, 145–146 diaphragmatic, 155–156, 245–246 metal, 275–276 motion, hurricane sign, 149–150

428

Index

motion, patient, 245–246 Azathioprine, sarcoidosis, 30 Background activity incorrect, 99mTc-RBC ventriculogram, left ventricle, 143–144 Barium, gamma photon attenuation, 411–412 Bile leak, 357–358 Biliary atresia, 91–92 Biliary excretion, tracer in bowel, 86 Biliary tract, 347–358 bile leak, 357–358 cholecystitis, 94 cholecystitis, acute acalculous, rim sign, 353–354 cholecystitis, morphine augmentation, 347–348 gallbladder ejection fraction, CCK infusion rate, 349–350 morphine augmentation, 347–348 preferential gallbladder filling, normal variant, 351–352 right portal vein thrombosis, 355–356 Bisphosphonates, Paget disease, 160 Bleeding scan. See 99mTc-RBC bleeding scan Bone marrow 99mTc-sulfur colloid imaging ( See 99mTc-sulfur colloid bone marrow imaging) hypercellular, knee replacement infection, 45–46 localized expansion, 41–42 Bone metastases 223Ra-dichloride, 337–338 scintigraphy survey, 191–192 Bone pain palliation other radiopharmaceuticals, 335–336 samarium, 335–336 Bone scintigraphy, 99mTc-MDP or HDP/25, 159–192 calcification, dystrophic, 173–174 calcification, metastatic, and renal osteodystrophy, 171–172 cerebral infarct, bone tracer uptake, 165–166 complex regional pain syndrome, 187–188 compression fractures, acute and chronic, 181–182 flare phenomenon, 163–164 heterotopic ossification, 167–168 hypertrophic osteoarthopathy, 169–170 metastatic survey, SPECT/CT added value, 191–192 mucinous colon metastatic cancer, 173–174 osteomyelitis and cellulitis, 189–190 os trigonum syndrome, 177–178 Paget disease, 159–160 Paget disease, and metastatic prostate cancer, 161–162

plantar fasciitis and metatarsal stress fracture, 179–180 sacral insufficiency fracture and multiple rib fractures, 183–184 shin split and stress fracture, 185–186 skeletal metastases, prostate cancer, 161–162 superscan, 175–176 Brain death, 5–6 Brain, hypometabolic or photopenic defects, 201–202 Brain metastases melanoma, 201–202 recurrent, 21–22 Brain necrosis, post-radiation, 22 Breast attenuation artifact, exercise MPI, 145–146 Breast cancer breast lymphoscintigraphy, 285–286 flare phenomenon, 163–164 incidental pneumonia, 235–236 sentinel lymph node biopsy, 286 staging, 18F-FDG PET-CT, 235–236 Breastfeeding, 84 metabolically active glandular tissues, 237–238 Breast lymphoscintigraphy, 285–286 Bronchial obstruction, reverse V/Q mismatch, 77–78 Bronchioloalveolar carcinoma, 215–216 Bronchogenic carcinoma, hypertrophic osteoarthropathy, 170 Brown adipose tissue, metabolically active, 211–212 CA-125 rising, with ovarian cancer, 261–262 Calcification dystrophic, 173–174 dystrophic, bone-seeking radiopharmaceuticals, 166 metastatic, renal osteodystrophy, 171–172 Calcimimetic therapy hyperparathyroidism, secondary, parathyroid hyperplasia, 320 parathyroid adenoma, 314, 316 parathyroid carcinoma, 318 Camera-based GFR measurement, 399–400 Captopril, renal artery stenosis, 403–404 Carcinoid tumor, 279–280 Carcinoma bronchioloalveolar, 215–216 bronchogenic, hypertrophic osteoarthropathy, 170 gastric, recurrent, 243–244 hepatocellular, 362 lung, adenocarcinoma in situ, 215–216 parathyroid, 317–318 peritoneal carcinomatosis, 262

renal cell, incidental, 253–254 Cardiac defibrillator, attenuation artifacts, 275–276 Cardiac sarcoid, 141–142 Cardiac shunt, right-to-left, left pulmonary artery atresia, 121–122 Causalgia, 187–188 Cavernous hemangioma, 364 Cellulitis, 190 Cerebellar diaschisis, crossed, chronic infarct, 15–16 Cerebral infarct, bone tracer uptake, 165–166 Cerebrospinal fluid (CSF) injection, 111In-DTPA, 18 shunt failure, 20 Cervical cancer metastatic, 255–256 staging, 256 Child abuse, traumatic, 107–108 Cholecystitis, 94 acute acalculous, rim sign, 353–354 morphine augmentation, 347–348 Cholecystokinin (CCK) infusion rate, gallbladder ejection fraction, 349–350 pretreatment, preferential gallbladder filling, 347–348 Cholescintigraphy, 99mTc-disofenin CCK infusion rate, gallbladder ejection fraction, 349–350 CCK pretreatment, preferential gallbladder filling, 351–352 cholecystitis, acute acalculous, rim sign, 353–354 Cholescintigraphy, 99mTc-mebrofenin bile leak, 357–358 cholestasis, intrahepatic, 359–360 focal nodular hyperplasia, 361–362 portal vein thrombosis, right, 355–356 Cholestasis drug-induced, 359–360 extrahepatic, 360 intrahepatic, 359–360 Cholinesterase inhibitors, Alzheimer’s disease, 10 Chronic obstructive pulmonary disease, 67–70 stripe sign, 71–72 Cimetidine, 99mTc-sodium pertechnetate Meckel scan, 96 Cisternogram, radionuclide, normal pressure hydrocephalus, 17–18 Colitis, pseudomembranous, 33–34 Colon cancer, metastatic, 257–258 99mTc-MAA and 90Y yttrium radioembolization, hepatic arterial perfusion scintigraphy, 367–368 mucinous, 173–174 sigmoid, synchronous colon cancer, 247–248

Index

429

Colon cancer, unknown primary, 249–250 Colonic uptake, FDG, metformin-associated, 267–268 Colorectal cancer, synchronous, 247–248 Complex regional pain syndrome, 187–188 Compression fractures, acute and chronic, 181–182 Coronary artery disease (CAD), myocardial perfusion imaging attenuation artifact, diaphragmatic, 155–156 detection, normal pharmacological stress, 131–132 dilated cardiomyopathy, non-ischemic, 151–152 exercise, abnormal, 133–134 exercise, breast attenuation artifact, 145–146 exercise, reporting, 129–130 LAD ischemia, transient ischemic dilatation, 137–138 left bundle branch block, fixed septal perfusion defect, 147–148 motion artifact, hurricane sign, 149–150 stable disease, 135–136 Coronary artery occlusion, exercise MPI, 133–134 Corpus luteum cyst, metabolically active, 257–258 Cricoarytenoid muscle, 18F-FDG uptake, 205–206 Crossed cerebellar diaschisis, chronic infarct, 15–16 Cross-fused pelvic kidneys, 397–398 Cross-fused renal ectopia, 398 DaTscan (123I-Ioflupan) dementia with Lewy bodies, 14 parkinsonism, 14 D-dimer, 63-64 Dementia Alzheimer disease, 9–10 FDG-PET, 12 frontotemporal, 11–12 Parkinson’s, 10 SPECT, 12 Dementia with Lewy bodies (DLB), 10, 13–14 Diaphragmatic attenuation artifact, 245–246 Dilated cardiomyopathy, non-ischemic, pharmacological stress MPI, 151–152 Dipyridamole, pharmacological stress MPI, 131–132 Discordant nodule, 304 Dobutamine, pharmacological stress MPI, 131–132 Doxorubicin, LV function, 153–154 Dystrophic calcification, 173–174 bone-seeking radiopharmaceuticals, 166 Eating before 18F-FDG PET-CT, biodistribution, 197–198 Ectopia, cross-fused renal, 398

430

Index

Ectopic gastric mucosa, 381–382 Meckel diverticula, 95–96 Ectopic parathyroid adenoma, 321–322 Ectopic thyroid gland, 105–106 neonatal hypothyroidism, 305–306 Endograft infection, abdominal aortic, 53–54 Endometrium, FDG physiologic uptake, 259–260 End-stage renal disease, metastatic calcification and renal osteodystrophy, 171–172 Epilepsy, left temporal interictal seizure focus, 3–4 Esophageal cancer, 241–242 staging, 18F-FDG PET-CT, 233–234 Exercise before 18F-FDG PET-CT, excessive, 198, 200 Exercise myocardial perfusion imaging. See Myocardial perfusion imaging (MPI), exercise stress Fallopian tube physiologic uptake, FDG, 259–260 Fatigue stress, 126 Feeding gastrostomy entry site, physiologic uptake, 49–50 Femoral head avascular necrosis, Perthes disease, 117–118 Femoral-popliteal prosthetic vascular graft infection, 37–38 Fever of unknown origin causes and presentation, 58 non-Hodgkin lymphoma, 57–58 Fibrous dysplasia, polyostotic, 111–112 Flare phenomenon, 163–164 Flip-flop phenomenon, 274, 392 Flu shot, inflammatory/reactive lymph nodes from, 271–272 Focal nodular hyperplasia, 361–362 Frontotemporal dementia, 11–12 Furosemide 99mTc-MAG3 diuretic renogram, 99–100, 393–394 99mTc-MAG3 renal scan, hydronephrosis, left renal artery stenosis, 404 Gallbladder CCK infusion rate, ejection fraction, 349–350 CCK pretreatment, preferential filling, 351–352 delayed or non-visualization, 348 Gamma photon attenuation, barium, 411–412 Gastric carcinoma, recurrent, 243–244 Gastric emptying normal, 373–374 rapid, 377–378 Gastric mucosa, ectopic, 381–382 Meckel diverticula, 95–96

Gastric physiologic uptake, FDG, 243–244 Gastrointestinal bleeding. See also 99mTc-RBC bleeding scan ectopic gastric mucosa, 381–382 false positive GI, free pertechnetate, 387–388 gamma photon attenuation, barium, 411–412 intraperitoneal, acute, 385–386 large bowel, acute, 383–384 signs, 384 Gastrointestinal tract, 373–388. See also specific disorders ectopic gastric mucosa, 381–382 ectopic gastric mucosa, Meckel diverticula, 95–96 gastric emptying, normal, 373–374 gastric emptying, rapid, 377–378 gastroparesis, 375–376 tracheobronchial aspiration, 97–98, 379–380 Gastroparesis, 375–376 Gastrostomy, feeding, entry-site physiologic uptake, 49–50 G-CSF effects, FDG PET-CT, 273–274 GFR measurement, camera-based, 399–400 Glucagon, 99mTc-sodium pertechnetate Meckel scan, 96 Goiter, toxic multinodular, vs. Graves disease, 301–302 Granulating wounds, leukocyte accumulation, 49–50 Graves disease (hyperthyroidism) 123I-sodium iodide, 293–294, 297–298 131I therapy, 294, 298, 302, 327–328 radioiodine therapy, recent, 409–410 vs. toxic multinodular goiter, 301–302 Growth factors, hematopoietic, FDG PET-CT effects, 273–274 Hamartoma, pulmonary, FDG-avid pulmonary nodule, 217–218 Hampton hump, 83–84 Hardware infection, spinal osteomyelitis, 55–56 Hashimoto thyroiditis, 209–210 Hemangioma cavernous, 364 hepatic, 363–364 Hematopoietic stimulating factors, FDG PET-CT effects, 273–274 Hepatic adenoma, 362 Hepatic arterial perfusion scintigraphy, 99mTc-MAA with 90Y yttrium radioembolization of metastatic colon cancer, 367–368 extrahepatic GI perfusion, catheter positioning, 369–370

Hepatic hemangioma, 363–364 Hepatocellular carcinoma, 362 Hepatorenal syndrome, 396 Heterotopic ossification, 167–168 Hibernating viable myocardium, LAD territory, 139–140 Hilar tumor, unilateral V/Q mismatch, 81–82 Hip replacement bone scan, 60 total, infected right, 59–60 Hodgkin lymphoma post-therapy lymphoma, 229–230 staging, FDG PET-CT, 269–270 Honda sign, 183–184 Hot nose sign, 5–6 Hot spots MAA particle clumping, 87–88 over-correction, 275–276 Hurricane sign, myocardial perfusion imaging, 149–150 Hydrocephalus, normal pressure, 17–18 Hydronephrosis, non-obstructive, 99–100 Hypercellular bone marrow, total knee replacement infection, 45–46 Hyperglycemia, 200 Hyperinsulinemia, 200 Hyperparathyroidism. See also Parathyroid adenoma secondary, with parathyroid hyperplasia, 319–320 Hyperthyroidism 131I therapy, 327–328 subacute thyroiditis, 295–296 thyroid nodule, autonomous, 299–300, 327–328 Hyperthyroidism (Graves) 123I-sodium iodide, 293–294, 297–298 131I therapy, 294, 298, 302, 327–328 recent radioiodine therapy, 409–410 vs. toxic multinodular goiter, 301–302 Hypertrophic osteoarthopathy, 169–170 Hypothyroidism congenital, 306 neonatal, ectopic thyroid gland, 305–306 Ictal PET, seizure focus, 4 Ictal SPECT, seizure focus, 4 Implantable cardiac defibrillator, attenuation artifacts, 275–276 Incidental adrenal adenoma, 251–252 Incidental renal cell carcinoma, 253–254 Incidental thyroid nodule, 207–208

Index

431

Infarct cerebral, bone tracer uptake, 165–166 crossed cerebellar diaschisis, chronic, 15–16 myocardial, Tc-99m pyrophosphate, 166 obtuse marginal and posterior descending artery, 135–136 Infectious colitis, gamma photon attenuation, barium, 411–412 Infliximab, sarcoidosis, 30 Influenza vaccination, lymph nodes inflammatory/ reactive, 271–272 Insufficiency fracture, sacral, 183–184 Intensity setting suboptimal, false-negative 99mTc-sulfur colloid scan, 417–418 Interictal PET, seizure focus, 3–4 Interstitial nephritis, acute, 25–26 Intraperitoneal bleeding, acute, 385–386 Ischemia LAD coronary artery, transient ischemic dilatation, 137–138 middle cerebral artery, 7–8 Ischiopubic synchondrosis, 109–110 Kidneys, cross-fused pelvic, 397–398 Kidney transplant acute tubular necrosis, urine leak, 401–402 other complications, 402 Knee replacement bone scan, 60 total, infected, hypercellular bone marrow, 45–46 Lactation, metabolically active glandular tissues, 237–238 Lambda sign, 30 Laryngeal nerve, head and neck tumors, 206 Left bundle branch block, fixed septal perfusion defect, 147–148 Left pulmonary artery atresia, right-to-left cardiac shunt, 121–122 Legg-Calve-Perthes disease, 117–118 Lingual thyroid, 105–106 Lipomatous hypertrophy of the interartrial septum (LHIS), 233–234 Liver, 359–370 90Y yttrium radioembolization of metastatic colon cancer, 367–368 cholestasis, intrahepatic, 359–360 extrahepatic GI perfusion, catheter positioning, 369–370 focal nodular hyperplasia, 361–362 hepatic hemangioma, 363–364

432

Index

right portal vein thrombosis, 355–356 Lung cancer adenocarcinoma in situ, 215–216 initial staging, distant metastases, 221–222 initial staging, TNM, 218, 219–220 metastatic, 209–210 recurrent, 205–206 solitary pulmonary nodule, FDG-avid, 213–214 Lung perfusion, normal, 63–64 Lymphedema, 289–290 Lymph nodes, FDG-avid, inflammatory/reactive, flu shot, 271–272 Lymph obstruction, radiotherapy, 226 Lymphoma. See also specific types post-therapy, 229–230 staging, FDG PET-CT, 269–270 Lymphoscintigraphy breast, 285–286 lymphedema, lower extremity, 289–290 melanoma, 287–288 MAA particle clumping, hot spots, 87–88 McCune-Albright syndrome, 112 polyostotic fibrous dysplasia, 111–112 Meckel diverticula, 95–96 Melanoma brain metastases, 201–202 lymphoscintigraphy, sentinel lymph node mapping, 287–288 Metal, attenuation artifact, 275–276 Metastases calcification, renal osteodystrophy, 171–172 cervical cancer, 255–256 SPECT/CT survey, 191–192 Metastases, bone 223Ra-dichloride, 337–338 scintigraphy survey, 191–192 Metastases, brain melanoma, 201–202 Metastases, colon cancer, 257–258 99mTc-MAA hepatic arterial perfusion scintigraphy, with 90Y yttrium radioembolization, 367–368 mucinous, 173–174 sigmoid, synchronous colon cancer, 247–248 Metastases, lung cancer, 209–210, 221–222 initial staging, 221–222 Metastases, lung, papillary thyroid cancer, decreasing iodine avidity, 311–312 Metastases, skeletal prostate cancer, 161–162 superscan, 175–176

Metastatic calcification, 171–172 Metastatic survey, SPECT/CT with bone scintigraphy, 191–192 Metatarsal stress fracture, 179–180 Metformin, FDG colonic uptake, 267–268 MIBG. See 123I-meta-iodobenzylguanine (123I-MIBG) scans Mickey Mouse, Paget disease, 161 Morphine augmentation, 347–348 Motion artifact, 245–246 hurricane sign, 149–150 myocardial perfusion imaging, CAD, 149–150 Mouse face, Paget disease, 161 Multicystic dysplastic kidney, 101–102 Multiple myeloma, 265–266 Myocardial infarct, Tc-99m pyrophosphate, 166 Myocardial perfusion imaging (MPI), exercise stress abnormal, 133–134 attenuation artifact, breast, 145–146 attenuation artifact, diaphragmatic, 155–156 left bundle branch block, fixed septal perfusion defect, 147–148 motion artifact, hurricane sign, 149–150 reporting, 129–130 Myocardial perfusion imaging (MPI), pharmacological stress dilated cardiomyopathy, non-ischemic, 151–152 hibernating viable myocardium, 139–140 infarction, obtuse marginal and PDA territory, 135–136 LAD ischemia, transient ischemic dilatation, 137–138 normal, 131–132 Nasopharyngeal cancer, 203–204 Neonatal hypothyroidism, ectopic thyroid gland, 305–306 Nephritis, acute interstitial, 25–26 Neuroblastoma 123I-MIBG scan, 119–120 123I-MIBG scans before and after 131I-MIBG therapy, 333–334 Neuropathic joint, osteomyelitis, 43–44 Non-accidental trauma, child abuse, 107–108 Non-Hodgkin lymphoma 18F-FDG PET-CT, 57–58 111In-ibritumomab tiuxetan biodistribution, 341–342 131I-tositumomab biodistribution, 343–344 fever of unknown origin, 57–58 radioimmunotherapy, 339–340

thymic rebounds, 227–228 Non-ischemic dilated cardiomyopathy, pharmacological stress MPI, 151–152 Normal pressure hydrocephalus, radionuclide cisternogram, 17–18 Oncology, 18F-FDG PET-CT, 195–276 adrenal adenoma, incidental, 251–252 brain malignancy, recurrent, 21–22 breast cancer, incidental pneumonia, 235–236 brown adipose tissue, metabolically active, 211–212 cervical cancer, metastatic, 255–256 colon cancer, metastatic sigmoid, synchronous colon cancer, 247–248 colon cancer, unknown primary, 249–250 corpus luteum cyst, metabolically active, 257–258 esophageal cancer, 241–242 esophageal cancer, staging, 233–234 gastric carcinoma, recurrent, 243–244 lung cancer, adenocarcinoma in situ, 215–216 lung cancer, FDG-avid solitary pulmonary nodule, 213–214 lung cancer, initial staging, distant metastases, 221–222 lung cancer, initial staging, TNM, 219–220 lung cancer, metastatic, 209–210 lung cancer, recurrent, 205–206 lymphoma, non-Hodgkin, fever of unknown origin, 57–58 lymphoma, post-therapy, 229–230 lymphoma staging, 269–270 melanoma, 201–202 multiple myeloma, 265–266 nasopharyngeal cancer, 203–204 ovarian cancer and CA-125 rising, 261–262 pulmonary hamartoma, 217–218 renal cell carcinoma, incidental, 253–254 synovial sarcoma, 263–264 Osteoid osteoma, 113–114 Osteomyelitis, 115–116, 189–190 111In-labeled leukocytes + 99mTc-sulfur colloid, diagnosis, 41–42 111In-labeled leukocytes + 99mTc-sulfur colloid, neuropathic joint, 43–44 Osteomyelitis, spinal, 28, 35–36 67Ga-citrate, 27–28 111In-labeled leukocyte imaging, 35–36 infected hardware, 55–56 psoas abscess, 27–28 Os trigonum syndrome, 177–178

Index

433

Ovarian cancer CA-125 rising, 261–262 recurrent, 261–262 Overuse stress, 126 Paget disease, 159–160 metastatic prostate cancer, 161–162 Papillary thyroid cancer, progressive lung metastases, decreasing iodine avidity, 311–312 Parallel-hole collimation, low-resolution images, 414 Parallex error, 407–408 Parathyroid adenoma dual-isotope technique, 315–316 ectopic parathyroid, 321–322 single-isotope dual-phase technique, 313–314 thymoma (mixed type), 323–324 Parathyroid carcinoma, 317–318 Parathyroid hyperplasia, secondary hyperparathyroidism, 319–320 Parkinsonism DaTscan abnormal, 14 non-neurodegenerative, 14 Parkinson’s dementia, 10 Pars interarticularis increased uptake, 124 L4 bilateral pars stress, spondylolysis, 123–124 Pars stress, 124 Pelvic kidneys, cross-fused, 397–398 Pentagastrin, 99mTc-sodium pertechnetate Meckel scan, 96 Perfusion-metabolism mismatch cardiac sarcoid, 141–142 hibernating viable myocardium, 139–140 Perfusion, pulmonary, 80 Perfusion shunting, lower lobes, PEEP, 79–80 Perfusion SPECT, dementia, 12 Perfusion stress test, 8 Perfusion tracers, 5–6. See also specific tracers Periosteitis, traction, 185–186 Peritoneal carcinomatosis, 262 Peritoneal scintigraphy, before intraperitoneal 32P, 331–332 Pertechnetate, free, false positive GI bleeding scan, 387–388 Perthes disease, 117–118 PET/CT, oncology. See Oncology, 18F-FDG PET-CT; specific cancers Phenobarbital pretreatment, 99mTc-mebrofenin hepatobiliary scan, 85–86 Pheochromocytoma, 281–282

434

Index

Photomultiplier tube artifact, photopeak energy setting, 415–416 Photopeak energy setting incorrect, 414 camera head-2 drifting, 413–414 photomultiplier tube artifact, 415–416 Physiologic uptake, 18F-FDG after drinking water, 243–244 endometrium, 259–260 fallopian tubes, 259–260 gastric, 243–244 testicular, 267–268 thymus, 228 Physiologic uptake, 111In-labeled leukocytes feeding gastrostomy entry site, 45–46, 49–50 pulmonary, 39–40 Plantar fasciitis, 179–180 Pleural effusion radiotherapy, 226 reverse V/Q mismatch, 77–78 Pleuritis, radiotherapy, 226 Pleurodesesis, talc crystal deposits, 225–226 Pneumocystis carinii (jiroveci) pneumonia (PCP), 31–32 Pneumonia incidental, with breast cancer, 235–236 P. carinii (jiroveci), 31–32 reverse V/Q mismatch, 77–78 Pneumonitis, radiation, 223–224 Polymyositis, statin-associated, 199–200 Polyostotic fibrous dysplasia, 111–112 Portal vein thrombosis, right, 355–356 Posterior descending artery infarction, MPI, 135–136 Post-radiation necrosis, brain, 22 Preferential gallbladder filling, CCK pretreatment, 351–352 Propylthiouracil, Graves disease, 294, 298 Prostate cancer flare phenomenon, 163–164 metastatic, Paget disease, 161–162 Prosthetic graft infection, femoral-popliteal vascular, 37–38 Pseudomembranous colitis, 33–34 Psoas abscess, with spinal osteomyelitis, 27–28 Pulmonary artery atresia, left, with right-to-left cardiac shunt, 121–122 Pulmonary embolism, 65–66, 70 D-dimer, 64 triple match (3M), 75–76 V/Q mismatch, 83–84

Pulmonary hamartoma, FDG-avid pulmonary nodule, false positive, 217–218 Pulmonary nodule, solitary, 213–214 Radiation pneumonitis, 223–224 Radioimmunotherapy, 339–340 Radionuclide cystogram, direct, vesicoureteral reflux, 103–104 Radionuclide therapy and pre-therapy evaluation, 327–344 111In-ibritumomab tiuxetan biodistribution, 341–342 123I-MIBG scans, before and after 131I-MIBG therapy, neuroblastoma, 333–334 131I therapy, differentiated thyroid cancer, 329–330 131I therapy, hyperthyroidism, 294, 298, 302, 327–328, 409–410 131I therapy, recent, 409–410 131I-tositumomab biodistribution, 343–344 223Ra-dichloride, bone metastases, 337–338 peritoneal scintigraphy before intraperitoneal 32P, 331–332 radioimmunotherapy-1, 339–340 samarium, bone pain palliation, 335–336 Reactive airway disease, 68 Reflex sympathetic dystrophy, 187–188 Regadenoson, stress myocardial perfusion imaging fixed septal perfusion defect, left bundle branch block, 147–148 infarction, obtuse marginal and PDA territory, 135–136 normal, 131–132 transient ischemic dilatation with mild ischemia in LAD territory, 137–138 Renal artery stenosis, hemodynamically significant left, 403–404 Renal cell carcinoma, incidental, 253–254 Renal cortical scintigraphy, 99mTc-DMSA, 100 Renal ectopia, cross-fused, 398 Renal osteodystrophy, 171–172 Renal scintigraphy, 391–404 acute tubular necrosis, 395–396 acute tubular necrosis, urine leak, 401–402 cross-fused pelvic kidneys, 397–398 GFR measurement, camera-based, 399–400 left renal artery stenosis, 403–404 normal renal scan, 391–392 urinary tract obstruction, ureteropelvic junction, 393–394 Renogram, 99mTc-MAG3 diuretic, hydronephrosis, non-obstructive, 99–100

Retrosternal thyroid, 407–408 Reverse V/Q mismatch, 77–78 atelectasis, 80 Rhabdomyolysis, 200 Rib fractures, multiple, 183–184 Right-to-left cardiac shunt, left pulmonary artery atresia, 121–122 Rim sign, 353–354 Sacral insufficiency fracture, 183–184 Salivagram, 98 99mTc-sulfur colloid radionuclide, 97–98 Samarium (153Sm-EDTMP), bone pain palliation, 335–336 Sarcoidosis, 231–232 18F-FDG PET-CT, 51–52, 231–232 67Ga-citrate SPECT-CT, 29–30 Cardiac, 141–142 Sarcoma, soft tissue, FDG PET-CT, 264 synovial, 263–264 Seizure focus, interictal, left temporal lobe, 3–4 Sentinel lymph nodes, 287–288 breast, 286 melanoma, 287–288 Septal perfusion defect, fixed, left bundle branch block, 147–148 Shin split, 185–186 Shunt cardiac right-to-left, left pulmonary artery atresia, 121–122 perfusion, lower lobes, PEEP, 79–80 ventriculoperitoneal, 19–20 Solitary pulmonary nodule, FDG-avid, 213–214 Somatostatin receptor imaging, carcinoid tumor, 279–280 Spinal osteomyelitis, 28, 35–36 67Ga-citrate, 27–28 111In-labeled leukocyte imaging, 35–36 infected hardware, 55–56 psoas abscess, 27–28 Spleen, accessory, false-negative 99mTc-sulfur colloid scan, 417–418 Splenules, 365–366 Spondylolysis123–124 Statin-associated polymyositis, 199–200 Stress, fatigue/overuse, 126 Stress fracture, 125–126, 185–186 metatarsal, 179–180 types, 126

Index

435

Stress myocardial perfusion imaging. See Myocardial perfusion imaging (MPI) Stripe sign, 71–72 pseudo, 73–74 Stroke, left anterior cerebral artery, 7–8 Superscan, 175–176 Synchondrosis, ischiopubic, 109–110 Talc crystal deposits, pleural, pleurodesesis, 225–226 Temporal lobe, hypometabolism and seizure focus, 3–4 Testes, undescended, 18F-FDG uptake, 267–268 Thrombolysis, massive pulmonary embolism, 66 Thymic rebound, 227–228 Thymoma/parathyroid adenoma (mixed type), 323–324 Thymus, PET and PET/CT physiologic uptake, 228 Thyroid ectopic, 105–106 lingual, 105–106 retrosternal, 407–408 Thyroid cancer differentiated, 131I therapy, 329–330 papillary, progressive lung metastases, decreasing iodine avidity, 311–312 pre-treatment 123I scan and post-therapy131I scan, 309–310 Thyroid disorders, 293–312. See also specific types Graves disease vs. toxic multinodular goiter, 301–302 hyperthyroidism, Graves disease, 293–294, 297–298 hyperthyroidism, subacute thyroiditis, 295–296 hypothyroidism, neonatal, ectopic thyroid gland, 305–306 papillary thyroid cancer, progressive lung metastases, decreasing iodine avidity, 311–312 parathyroid adenoma/thymoma (mixed type), 323–324 thyroid cancer, pre-treatment 123I scan and post-therapy131I scan, 309–310 thyroid hormone liver metabolism/radioiodine uptake in tooth filling, 307–308 thyroid nodule, autonomous (“hot”), 299–300, 327–328 thyroid nodule, nonfunctional (“cold”), 303–304 Thyroid gland ectopic, neonatal hypothyroidism, 305–306 FDG uptake, incidental, 221–222 Thyroid hormone, liver metabolism, 307–308

436

Index

Thyroid hormone replacement therapy lingual thyroid, 106 neonatal hypothyroidism, ectopic thyroid gland, 306 post-thyroidectomy, 308 Thyroiditis chronic, 222 Hashimoto, 209–210 subacute, 295–296 Thyroid nodule autonomous (“hot”), 299–300, 327–328 incidental, 207–208 nonfunctional (“cold”), 303–304 Tooth filling, radioiodine uptake, 307–308 Tositumomab + 131I-tositumomab, non-Hodgkin lymphoma, 340 Total hip replacement, infected right, 59–60 Total knee replacement, infected, hypercellular bone marrow, 45–46 Toxic multinodular goiter, vs. Graves disease, 301–302 Tracheobronchial aspiration, 99mTc-sulfur colloid, 379–380 salivagram, 97–98 Traction periosteitis, 185–186 Transient ischemic dilatation, LAD coronary artery territory, 137–138 Undescended testes, 18F-FDG uptake, 267–268 Ureteropelvic junction, urinary tract obstruction, 393–394 Urinary tract obstruction, ureteropelvic junction, 393–394 Urine leak, acute tubular necrosis and, 401–402 Urinoma, 402 Vascular graft infection, femoral-popliteal prosthetic, 37–38 Ventilation, normal, 63–64 Ventriculogram, radionuclide doxorubicin cardiotoxicity, LV function decreased, 153–154 incorrectly placed background activity overlapping spleen, 143–144 left ventricular ejection fraction, 154 Ventriculoperitoneal shunt flow, normal, 19–20 Vesicoureteral reflux, 103–104 Vitamin D replacement, secondary hyperparathyroidism, parathyroid hyperplasia, 320 Vocal cord 18F-FDG uptake, 205–206

V/Q match, triple match, radiographic abnormality, 75–76 V/Q mismatch differential diagnosis, 82 pulmonary embolism, 66–67, 83–84

pulmonary embolism, single on SPECT, 73–74 reverse, 77–78 reverse, atelectasis, 80 unilateral, centrally located tumor, 81–82

Index

437