ВУЗ: Не указан
Категория: Не указан
Дисциплина: Не указана
Добавлен: 22.10.2024
Просмотров: 353
Скачиваний: 0
Advanced Imaging of the Abdomen
Jovitas Skucas
Advanced Imaging
of the Abdomen
With 489 Figures in 1025 Parts
Jovitas Skucas, MD
Professor Emeritus, Department of Imaging Sciences, University of Rochester, Rochester, NY, USA
British Cataloging in Publication Data
A catalogue record for this book is available from the British Library.
Library of Congress Control Number 2005924309
ISBN-10: |
1-85233-992-6 |
e-ISBN 1-84628-169-5 |
ISBN-13: |
978-1-85233-992-0 |
|
Printed on acid-free paper.
© Springer-Verlag London Limited 2006
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers.
The use of registered names,trademarks,etc. in this publication does not imply,even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use.
Product liability: The publisher can give no guarantee for information about drug dosage and application thereof contained in this book. In every individual case the respective user must check its accuracy by consulting other pharmaceutical literature.
Printed in the United States of America. |
(BS/EB) |
9 8 7 6 5 4 3 2 1
Springer Science+Business Media springeronline.com
Preface
This book is an attempt to bridge the interface between referring clinicians and radiologists when faced with a patient suspected of having a complex or unusual abdominal condition. The emphasis is on the choice of imaging procedures, expected diagnostic yield, a discussion of pertinent imaging findings, and the possible differential diagnosis. The rapid proliferation of imaging techniques provides a bewildering array of choices to the referring physician. Thus when faced with a suspected biliary abnormality, should one suggest traditional endoscopic retrograde cholangiography, or is noninvasive and noncontrast magnetic resonance (MR) cholangiography or even contrast-aided computed tomography (CT) cholangiography more appropriate? What is the role of CT virtual colonoscopy? Is it limited to colon cancer screening or does it have a role in cancer staging?
This book discusses imaging topics of those structures that fall in the purview of the gastroenterologist, urologist, general surgeon, and related specialist. The anatomic limits of the abdomen are somewhat stretched to include the esophagus superiorly, and the aorta, inferior vena cava, and adjacent structures posteriorly. The emphasis is on new imaging findings and innovations. This book also discusses the clinical aspects of a disease needed to formulate a rational diagnostic approach, but basic research, results of animal studies, and imaging research are not discussed as they are not pertinent to clinical medicine. Because of space limitations, fetal imaging and choosing a contrast agent are not discussed. Also, laboratory findings and therapeutic options are not discussed, except for those having a bearing on subsequent diagnostic studies.
This book is intended to be used as a reference for the atypical and unique presentation and newer diagnostic imaging modalities. Publications of unusual clinical and imaging finding are accentuated, and common imaging studies of common disorders are only mentioned in passing, if they are applicable.
Traditionally, radiology texts have used a pathologically oriented outline. Subsequently it became the custom to discuss disorders from an imaging point of view. An attempt is made here to integrate clinical presentation with pertinent radiologic findings. The material is organized primarily along anatomic organ systems, with some exceptions. For instance, disorders of the adnexa involve the peritoneal cavity, but they are closely related to the female genital tract and thus are included in Chapter 12, Female Reproductive Organs, rather than the peritoneum chapter. Within each organ system the material is subdivided further along broad disorder categories, such as congenital, inflammation, tumors, etc., but a pragmatic clinical approach is adopted. For example, a
v
vi
PREFACE
history of trauma is usually known and thus imaging findings associated with acute trauma are discussed in separate sections.
It has been said that “to steal from one author is plagiarism, if you steal from many, it’s research” (1). With that definition in mind, this work, I hope, is research. The references are rather wide-ranging, but to make the text more readable the number of references is deliberately kept low and information that has diffused in the medical community is not referenced further. The cited references serve both as an acknowledgment to the original authors and as a guide to a more in-depth source on a particular topic.
An abbreviated format has been adopted in presenting published studies. Emphasis is on sensitivity and specificity (or false-positive rate), realizing that these provide an incomplete picture. Where applicable, the measurements given include a standard deviation. To maintain brevity, little additional statistical analysis is provided.
It is assumed that the reader has basic knowledge of abdominal imaging. The technical details about performing and interpreting various imaging modalities are omitted except when pertinent to new techniques and applications. Thus a statement such as
Tc99m-DTPA scintigraphy and color duplex US . . . could reliably differentiate minimal and not perfused renal allografts . . .
omits that scintigraphy consisted of analogue scans up to 60 minutes postinjection and that time-activity curves over the first 60 seconds after injection of 370 to 440MBq of technetium-99m-diethylenetriaminepentaacetic acid are obtained and classified by a perfusion score, the time between renal and iliac artery peaks and washout of the renogram curve; similarly, not mentioned is that color duplex ultrasonography (US) consists of a perfusion study in all sections of the graft and vascular anastomoses by colorcoded duplex sonography and that maximal blood flow velocity and resistive index in the renal artery are determined by a pulsed Doppler device. Most of these details are intuitive to the specialist performing such a test.
To avoid repetition, the more common imaging findings are not repeated for each imaging modality. Thus if a lesion contains fat, it is stated as such; it is not stated that this fat is hypodense with CT, hyperechoic with US, or hyperintense with T1-weighted MR sequences. The exception is if a specific imaging appearance is unique.
Indications for magnetic resonance imaging (MRI) are still evolving. In addition, as new imaging technology becomes available the imaging modality recommended for a particular application today may not be optimal tomorrow. Thus multislice helical CT techniques continue to expand application of CT angiography and interventional procedures, possibly at the expense of further rapid growth of MRI.
Numerous individuals contributed images to this book and their effort is gratefully acknowledged. Over the years many ex-residents have provided me with interesting studies from their daily practices and these are acknowledged. A special thanks goes to Jolanta Galdikaite, an illustrator in Kaunas, Lithuania, for the line drawings.
Jovitas Skucas, MD
Reference
1.Attributed to the Hollywood ne’er-do-well Wilson Mizner (1876–1933). Quoted in Green J. Chasing the Sun: Dictionary Makers and the Dictionaries They Make. New York: Henry Holt, 1996:19.
Contents
PART I: DIGESTIVE SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
1 |
|
1. |
Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
3 |
2. |
Stomach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
55 |
3. |
Duodenum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
107 |
4. Jejunum and Ileum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
125 |
|
5. Colon and Rectum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
185 |
|
6. |
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
279 |
7. |
Liver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
293 |
8. |
Gallbladder and Bile Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
419 |
9. |
Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
501 |
PART II: GENITOURINARY SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
569 |
10. Kidneys and Ureters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
11. Bladder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 685
12. Female Reproductive Organs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719
13. Male Reproductive Organs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801
vii
viii
CONTENTS
PART III: OTHER STRUCTURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
863 |
|
14. |
Peritoneum, Mesentery, and Extraperitoneal Soft Tissues . . . . . . . . . |
865 |
15. |
Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
933 |
16. |
Adrenals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
953 |
17. |
Abdominal Vasculature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
975 |
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
1047 |
|
Terminology
The term tumor is used in a broad sense for a focal growth, be it inflammatory, developmental, or neoplastic in nature. In solid organ chapters tumor is used synonymously with nodule.
A number of terms are in general use to describe computed tomography (CT), ultrasonography (US), and magnetic resonance (MR) imaging findings. Although the synonyms listed are self-evident to radiologists, they tend to be confusing to clinicians. For consistency, the following terminology is adopted:
Adopted Terms1 |
Synonyms |
CT2: |
|
Hypodense |
Hypoattenuating, low attenuation, low opacity |
Isodense |
Isoattenuating |
Hyperdense |
Hyperattenuating, high attenuation, high opacity |
US: |
|
Hypoechoic |
Hypogenic, hypoechogenic, echopenic, sonolucent |
Isoechoic |
Isogenic |
Hyperechoic |
Hypergenic, echogenic |
MR2,3: |
|
Hypointense |
Low signal intensity |
Isointense |
Intermediate signal intensity |
Hyperintense |
High signal intensity |
1 Density, echogenicity, and intensity are usually expressed in reference to an assumed internal standard, generally normal adjacent tissue parenchyma.
2 CT and MR precontrast and postcontrast appearances of a lesion varies. Also, the early postcontrast appearance (arterial phase) often differs from that seen on delayed images (venous phase or even later).
3 MR findings vary depending whether T1or T2-weighted sequences are imaged and on imaging parameters used. To avoid confusion, these MR terms are applied only to precontrast images. The terms hypoand hypervascular are used to describe tissue appearance after intravenous contrast injection. The term contrast agent has a different meaning in MR than usually applied to barium sulfate or the iodinated agents used in angiography and CT. MR contrast agents are not visualized directly; rather, their usefulness is based on their ability to change water proton relaxation times.
ix
1
Esophagus
Technique
Dynamic Recording
Videopharyngography, also called modified barium swallow,is an established technique providing dynamic recording in evaluating deglutition. Continuous image detection rather than pulsed fluoroscopy is preferred because transient laryngeal penetration is more difficult to detect with the latter.
Esophageal videofluoroscopy (videoesophagography) is preferred by some radiologists to evaluate esophageal tonicity and peristalsis, while most simply rely on fluoroscopic observation. Especially in a search for subtle peristaltic abnormalities, a recumbent patient position is preferred to eliminate gravity. Manometry and esophageal videofluoroscopy agreed 100% in a setting of normal esophageal function, in 90% for nonspecific motility disorders, 100% in diffuse esophageal spasm, and 90% in achalasia, but only in 50% for a “nutcracker” esophagus
(1).
A computer program can quantify esophageal wall motion using data obtained from an esophagogram, but whether such information is of clinical relevance remains to be established.
Speech therapists and some radiologists prefer a lateral view when evaluating swallowing. Nevertheless, a frontal view has much to offer during the pharyngeal phase. In experienced hands, laryngeal penetration is just as
readily detected in a frontal position and, in addition, rightand left-sided pharyngeal muscle function can be compared to each other. Oblique views are of occasional value.
High-speed magnetic resonance imaging (MRI) also evaluates dynamic deglutition (MR pharyngography), but clinical application of this technique is still evolving.
Barium Studies
Barium sulfate is the preferred contrast agent for intraluminal esophageal studies. Controversy exists, however, in a setting of a suspected leak, with some radiologists, especially in Europe, preferring water-soluble contrast (discussed below; see Trauma).
Abarium-rice mixture, mixed in equal proportions, has been proposed to evaluate esophageal motility disorders; a normal esophageal transit time for such a mixture is between 5 and 15 seconds. In patients with esophageal motility disorders, this simple and low-cost technique yields a transit time outside of these limits in over half (2). Nevertheless, it is not often employed and dynamic recording using various consistency barium products is more in vogue.
Children presenting with dysphagia are readily evaluated with an esophagram.
A11.5-mm barium tablet is commercially available. It serves no useful purpose in the face of an obvious stricture but is useful in detecting a subtle esophageal narrowing. The tablet is
3
4
designed to dissolve and thus is retained only temporarily proximal to a stricture. Normally the barium tablet should pass into the stomach within 20 seconds when using a standardized 45-degree incline position and ingesting 60 cc of water after swallowing the tablet; failure of tablet passage under these conditions suggests a persistent narrowing. These conclusions do not apply to a patient in a horizontal position.
A barium tablet has been used to screen for occult esophageal lesions during routine chest radiography but is rarely practiced today. A chewed barium tablet, barium-impregnated marshmallow bolus, and similar contrast have been largely supplanted by standardized meals in evaluating oral and pharyngeal dysfunction.
Computed Tomography
A low-density, high-viscosity barium paste ingested just before computed tomography (CT) scanning aids in outlining the esophageal lumen.A negative oral contrast agent, consisting of a vanilla-flavored paraffin emulsion, has been used during helical CT to evaluate chemotherapy of esophageal cancer (3) but is not widely employed.
Sufficiently rapid image acquisition of a region in question during a single breath-hold is feasible with multislice helical CT, allowing two-dimensional (2D) and 3D reconstructions.
Ultrasonography
The thyroid gland acts as an acoustic window of the cervical portion of the esophagus. The left liver lobe provides an acoustic window for study of reflux and the gastroesophageal junction.
Gray-scale ultrasonography (US) has been used to investigate oral motor function in children with neurologic impairment (4). Its full role is yet to be established.
Endoscopic US (endosonography), using a high-resolution 20MHz transducer, has the potential of becoming the most important imaging modality in esophageal cancer staging and evaluating other intramural lesions. Tumor extension to regional nodes can be detected. The current trend is that endosonography influences patient management, often toward less costly, less risky, and less invasive procedures. Endoluminal US data can provide 3D
ADVANCED IMAGING OF THE ABDOMEN
images, potentially aiding staging, but this technique is too new to draw conclusions.
Fine-needle aspiration biopsy using endoscopic US guidance is feasible.
Magnetic Resonance Imaging
Of all gastrointestinal structures, the esophagus is most prone to respiratory and cardiac motion artifacts. Cardiac-gated techniques are not often used because of the prolonged sequences.
Most radiologists do not opacify the esophagus during MR imaging.
Scintigraphy
Use of esophageal transit scintigraphy varies considerably among institutions and countries. Whether its diagnostic value approaches that of a barium study or manometry is debatable. The current indications for its use are when esophageal manometry is unavailable, when the patient cannot tolerate manometry, when there is clinical suspicion of a motility disorder but the manometry is equivocal, and when a serial response to therapy is desired.
Manometry
Esophageal manometry often serves as a gold standard when evaluating other imaging modalities for detecting and classifying esophageal motility abnormalities. Correlation with eventual clinical diagnoses, however, shows that it is an imperfect gold standard. Although temporal measures of intraluminal pressure at various sites in the esophagus, including the gastroesophageal junction, translate into esophageal tonicity and peristalsis values, many esophageal motility disorders have overlapping findings, and manometry is often simply reported as “nonspecific” or “compatible with” a certain disorder. These findings are, of course, not unique to manometry, and other dynamic imaging modalities also have similar limitations.
Manometry is not complication free. Thus esophageal perforation occurred in a patient during manometry, mediastinitis and bilateral pleural effusions developed, a distal esophageal perforation was detected, and an esophagectomy and gastric pull-through performed (5), but the patient died.