Shahid M. Hussain · Liver MRI

Shahid M. Hussain

Liver MRI

Correlation with Other Imaging Modalities and Histopathology

Forewords by

John L. Gollan, MD, PhD and Richard C. Semelka, MD

With 114 Figures in 1.865 Parts

Shahid M. Hussain, MD, PhD Professor of Radiology Director of Body MRI

Chief Abdominal Imaging

Department of Radiology

University of Nebraska Medical Center 981045 Nebraska Medical Center Omaha, NE 68198

USA

Email: smhussain@unmc.edu

ISBN 3-540-25552-4 Springer-Verlag Berlin Heidelberg New York

Library of Congress Control Number: 2006929204

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To Ellen, Emma, and Charlotte

Foreword I

In March 1973, a short paper was published in Nature, entitled „Image formation by induced local interaction; examples employing nuclear magnetic resonance.“ The author was Paul C. Lauterbur, a Professor of Chemistry at the State University of New York at Stony Brook. In this seminal manuscript the author described a new imaging technique which moved the single dimension of NMR spectroscopy to the dual dimension of spatial orientation, thereby resulting in the foundation of modern magnetic resonance (MR) imaging. Over the ensuing years, MR imaging has assumed an increasingly important role in clinical imaging. It distinguishes itself from other imaging modalities, such as ultrasound (US) or computed tomography (CT), by the unique ability to visualize specific tissue components in a non-in- vasive manner.

In the earlier days, diagnostic MR imaging was limited to cerebral and musculoskeletal diseases. Imaging of other areas which are more prone to movement through breathing (abdominal) or pulsation motions (cardiac) became available more recently, with the introduction of faster sequences and the development of more dedicated MR imaging coils. Currently, liver MRI is considered the cornerstone of abdominal imaging. In most centers, however, liver MRI is still employed largely as a problem solving modality, when US and CT have provided an unsatisfactory outcome. This truly is an unfortunate misconception, which should be abandoned in favor of MR imaging as the primary modality for detection and characterization of liver abnormalities. If applied in the form of state-of-the-art technology, MR imaging has the potential of providing an accurate diagnosis of focal liver lesions in the majority of cases, frequently obviating the need for more invasive strategies.

We are standing on the verge of a new breakthrough in MR imaging, with the introduction of clinical high field MRI systems, such as 3.0T, multiple coil elements, parallel imaging capabilities, stronger gradients, and faster computers. Collectively, these developments will undoubtedly initiate a new era in MR imaging of the liver. The author of this impressive text, Dr. Shahid Hussain, and our institution are on the forefront of these important developments. This textbook with its numerous high quality illustrations, including computer-generated drawings, state-of-the-art MR images and radiology-pathology correlations, provides an accurate and up-to-date overview of imaging findings of a wide spectrum of liver lesions. The manner in which the contents of this book are presented provides an intuitive, easy to read approach, albeit on the topic of liver nodules or the analysis of parenchymal disorders. This textbook will be of particular benefit for clinicians and radiologists involved in the diagnosis and management of hepatic diseases.

MRI imaging will most certainly continue to emerge as a key, primary imaging modality for a broad spectrum of liver diseases. Likewise, it is essential that MRI becomes increasingly familiar to those who provide care for patients with liver abnormalities. Hence, I highly recommend this book as a routine companion for radiologists whilst reviewing MR examinations in the clinical setting, as study book for professionals in-training, such as radiology and gastroenterology fellows, and as reference for more experienced hepatologists, gastroenterologists, surgeons and pathologists. This is an easy way to acquire new knowledge on the topic of MR imaging.

John L. Gollan, MD, PhD, FRACP, FRCP, FACP

Dean, College of Medicine,

University of Nebraska Medical Center,

Omaha, Nebraska, USA

Foreword II

Annually, many thousands of patients worldwide undergo imaging for the workup of a suspected or known abnormality of the liver. Cross-sectional imaging modalities, such as ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), are utilized in most centers to assess liver abnormalities. These modalities, often used in various combinations, have fundamental differences in data acquisition and hence differences in the type of physical characteristics of tissues that they interrogate.

The major focus of this book is to describe that MR imaging is an accurate technique for the evaluation of focal liver lesions. MR imaging can also be used to evaluate diffuse hepatic diseases, hepatic vascular abnormalities (MR angiography), and biliary diseases (MR cholangiography). In the near future, it will be feasible to evaluate functional aspects of the liver through the use of one or more combinations of current fast breath hold MR imaging sequences, and MR spectroscopy, diffusion-weighted imaging, perfusion imaging and non-proton imaging. MR imaging may soon play a unique role in molecular imaging of the liver, including the specific targeting of diseased tissues, as well as providing imaging guidance for future smart drugs or cell delivery systems.

The introduction of multiple coil elements, parallel imaging, stronger gradients, and faster computers will undoubtedly increase the cranio-caudal (z-) coverage substantially. High resolution MR imaging of the abdomen and pelvis in a single exam (like CT) without the use of ionizing radiation and nephrotoxic iodine contrast media will become a reality. Liver MRI, however, will remain a crucial part of such a strategy that is important for staging malignancies in the abdomen.

By nature MR imaging is considered a complex modality by many radiologists and clinicians. This book succeeds in making liver MRI more accessible to the experienced as well as novice users who intend to use MR imaging for evaluation of liver abnormalities. MR imaging findings and concepts are presented and explained in simple-to-interpret computer-generated drawings. Additional explanation is provided by the radiology-pathology correlation and comparison to other imaging modalities. A particular strength of Dr. Hussain’s book is the extensive correlation with other imaging modalities, to allow the reader to have a fuller understanding of how the imaging modalities interrelate.

Shahid Hussain is one of the world’s recognized authorities on imaging of diseases of the liver. This book reveals his breadth of knowledge on this subject. Therefore, I can highly recommend this book to radiologists, clinicians, residents, radiology technicians, and students. Radiologists and radiology residents may particularly find this book useful during the reporting process of liver MR imaging exams.

Richard C. Semelka, MD

Professor and Vice-Chair of Research,

Director of MRI Services,

Department of Radiology,

University of North Carolina at Chapel Hill,

Chapel Hill, North Carolina, USA

Preface

This book provides a practical approach for MR imaging of the focal and diffuse liver lesions based on the state-of-the-art MR imaging sequences, computer-generated drawings, concise figure captions, relevant and systematic (differential) diagnostic information, recent literature references, and patient management possibilities. MR imaging findings are correlated to ultrasound, computed tomography, and pathology when appropriate. This book will greatly benefit all professionals interested and involved in imaging, diagnosis, and treatment of focal and diffuse liver lesions, including radiologists, gastroenterologists, surgeons, pathologists, MR physicists, MRI clinical scientists, radiology and other residents, MR technicians, and students.

This manuscript has especially benefited from the critical review by the following Body MR imaging experts and colleagues: Franz Sulzer, MD and Indra C. van den Bos, MD.

In addition, I am grateful to the following colleagues and friends for their continuous support during the past several years: Richard C. Semelka, MD, Donald G. Mitchell, MD, Eric K. Outwater, MD, Caroline Reinhold, MD, Mich`ele A. Brown, MD, Masayuki Kanematsu, MD, Nikolaos L. Kelekis, MD, Susan M. Ascher, MD, Sat Somers, MD, N. Cem Balci, MD, Diego R. Martin, MD, Till R. Bader, MD, PhD, Kees van Kuijk, MD, PhD, Peter M.T. Pattynama, MD, PhD, Abida Z. Ginai, MD, PhD, Jan C. den Hollander, MD, Robert A. de Man, MD, PhD, Pieter E. Zondervan, MD, Türkan Terkivatan, MD, PhD, Jan N.M. IJzermans, MD, PhD, Kees Verhoef, MD, Gabriel P. Krestin, MD, PhD, Johannes L. Bloem, MD, PhD, Reginald Goei, MD, PhD, Roy S. Dwarkasing, MD, Remy W.F. Geenen, MD, Jayant R. Kichari, MD, and Steven D. Wexner, MD, FACS, FRCS.

Finally, I am thankful to John L. Gollan, MD, PhD, Dean of the College of Medicine, and Craig W. Walker, MD, Professor and Chairman of the Department of Radiology at the University of Nebraska Medical Center, for their incessant support and for providing a positive and a stimulating academic environment.

Shahid M Hussain, MD, PhD Professor of Radiology Director of Body MRI Chief Abdominal Imaging Department of Radiology

University of Nebraska Medical Center 981045 Nebraska Medical Center Omaha, NE 68198 USA

Email: smhussain@unmc.edu

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How To Use This Book

MR imaging is a unique imaging modality which allows a comprehensive evaluation of the liver and includes the visualization of the soft tissue components based on various T1and T2-weighted sequences, the vascularity based on routine dynamic gadolinium-enhanced imaging and MR angiography, and the biliary tree based on MR cholangiography. The versatility of MR imaging and the amount of the diagnostic information obtained from a single liver MRI examination may intimidate the reader. This book provides a unique approach to simplifying liver MRI.

To diagnose most liver diseases, four sequences are most important to evaluate. These include: (1) a fat-suppressed T2-weighted sequence (or an equivalent sequence); (2) a T1 in-phase gradient-echo sequence; (3) arterial-phase dynamic gadolinium-enhanced images; and (4) delayed-phase gadoliniumenhanced images. This book provides computer-generated drawings of these or four similar MRI sequences to highlight and explain the most important diagnostic findings. The direct MRI drawing comparison facilitates the interpretation of the important imaging findings. In addition, background information and up-to-date available literature is provided, with correlation to other imaging modalities (US, CT) and pathology.

Liver abnormalities are divided into five major categories. Within each category, subcategories are provided and more specific diagnoses are listed alphabetically. Based on this book, liver MRI can be approached as follows:

Step I: Categorize the liver abnormality into one of the five groups:

1.High-fluid content liver lesions (high signal on T2 which persists on longer T2)

2.Solid liver lesions (moderately high signal on T2; similar to the spleen or lower)

3.Diffuse liver lesions (expressed by the diffuse or segmental abnormal signal or enhancement)

4.Vascular liver lesions (visible mainly in the arterial phase)

5.Biliary tree abnormalities (visible on T2-weighted and MRCP sequences)

Step II: Evaluate the signal intensity on fat-suppressed T2and T1-weighted sequences as well as gadolinium-enhanced images and attempt a more specific diagnosis.

Step III: Compare your working diagnosis to the specific examples within each category systematically and confirm your finding into a more definitive (differential) diagnosis.

This approach is consistently applied throughout the book, which shows that most liver lesions can be detected and characterized based on this method. At the end of the book, several examples of differential diagnostic comparisons have been provided of the most common liver lesions. The reader is encouraged to develop a similar approach during reading liver MRI exams in daily clinical practice. In addition, two appendices have been provided to explain a typical liver MR imaging protocol and the normal segmental anatomy of the liver.