Multi-slice and Dual-source CT in Cardiac Imaging

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2 I Ohnesorge Flohr Becker Knez Reiser Multi-slice and Dual-source CT in Cardiac Imaging Principles Protocols Indications Outlook Second Edition

3 III Bernd M. Ohnesorge Thomas G. Flohr Christoph R. Becker Andreas Knez Maximilian F. Reiser Multi-slice and Dual-source CT in Cardiac Imaging Principles Protocols Indications Outlook Second Edition With 316 Figures in 673 Separate Illustrations in Color and 26 Tables 123

4 IV Bernd M. Ohnesorge, PhD President Siemens Medical Solutions Group, China 7, Wangjing Zhonghuan Nanlu Chaoyang District, Beijing , P.R. China Thomas G. Flohr, PhD Head of CT Physics and Applications Development Siemens Medical Solutions, Division CT Siemensstrasse 1, Forchheim, Germany Christoph R. Becker, MD Section Head CT, Department of Clinical Radiology University of Munich, Klinikum Grosshadern Marchioninistrasse 15, Munich, Germany Andreas Knez, MD Section Head Imaging, Department of Cardiology University of Munich, Klinikum Grosshadern Marchioninistrasse 15, Munich, Germany Maximilian F. Reiser, MD Medical Director, Department of Clinical Radiology University of Munich, Klinikum Grosshadern Marchioninistrasse 15, Munich, Germany Library of Congress Control Number: ISBN Springer Berlin Heidelberg New York ISBN Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitations, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. Springer is part of Springer Science+Business Media http// Springer-Verlag Berlin Heidelberg 2007 Printed in Germany The use of general descriptive 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 protective laws and regulations and therefore free for general use. Product liability: The publishers cannot guarantee the accuracy of any information about dosage and application contained in this book. In every case the user must check such information by consulting the relevant literature. Medical Editor: Dr. Ute Heilmann, Heidelberg Desk Editor: Dörte Mennecke-Bühler, Heidelberg Production Editor: Kurt Teichmann, Mauer Cover-Design: Frido Steinen-Broo, estudio Calmar, Spain Typesetting: Verlagsservice Teichmann, Mauer Printed on acid-free paper 21/3151xq

5 Preface V Preface to the Second Edition Despite worldwide efforts to assess and control cardiovascular risk factors, cardiac diseases and in particular coronary artery disease (CAD) are still the foremost causes of death in the developed countries of Western Europe, North America and Asia and are becoming increasingly common in Eastern Europe and the developing world (Deanfield 2001). Approximately one in five deaths is currently related to cardiac disease in Europe and the US. Nearly 500,000 deaths caused by CAD are reported every year in the US, over 600,000 in Europe, 170,000 of these in Germany alone. Over 12 million US citizens have a history of CAD, while every year 1.1 million US and 300,000 German citizens suffer a coronary attack and more than 40% will die as a result of these attacks. Every second patient dies without prior symptoms and, in most cases, myocardial infarction occurs without warning. Once a blockage of the coronary arteries has occurred, death may ensue within a few minutes, even before hospitalization is possible. These alarming statistics highlight an acute need for tools to diagnose cardiac and coronary artery disease. Presently, the gold-standard modality for diagnosis of CAD is invasive selective coronary angiography. More than 2.5 million diagnostic coronary angiograms are performed every year in Europe and the US, but about 40% of them are not followed by subsequent interventional or surgical treatment and are conducted only for the purpose of ruling out CAD (Windecker 1999). These data show the significant need for and importance of reliable non-invasive imaging for early and preventive diagnosis of CAD and other cardiac diseases. Since its introduction by G. Hounsfield in 1972, X-ray computed tomography (CT) has become a reliable and widely used non-invasive imaging modality for vascular diagnosis, starting in the early 1990s with the advent of spiral CT. The reliability, simplicity and reproducibility of CT scanning could have made it a very interesting modality for non-invasive cardiac diagnosis. However, at that time imaging the heart and coronary arteries was not possible with general purpose CT scanners due to the high demands in terms of spatial and temporal resolution. As a result of dedicated development in cardiac CT scanning electron beam CT (EBCT) was introduced in With non-mechanical control and movement of the X-ray source, fixed detector system and ECG-correlated sequential scanning EBCT enabled extremely short image acquisition times to virtually freeze cardiac motion. However, the limited application spectrum of EBCT in general purpose use and in cardiac imaging has restricted distribution of the technology. The general purpose mechanical single-slice CT systems

6 VI Preface with sub-second rotation and ECG-correlated scanning that were introduced in 1994 have challenged EBCT in the domain of cardiac imaging. The early results were promising, but restrictions in spatial and temporal resolution have limited the application to cardiac work. In 1998 mechanical multi-slice CT systems with simultaneous acquisition of four slices were introduced by all major CT manufacturers. For the first time these scanners enabled ECG-correlated multi-slice acquisition at considerably faster volume coverage and higher spatial and temporal resolution for cardiac applications compared to single-slice scanners. Since then multi-slice technology has become standard for general purpose CT diagnosis with over 10,000 multi-slice CT scanners installed to date. Within just 5 years major performance advances have taken place in terms of enhancing the number of slices acquired per rotation from 4 to 8, from 8 to 16 and now even up to 64. With the recent introduction of dual-source CT a new development is under way that will further enhance the reliability and expand the spectrum of CT in cardiac imaging in the near future (Flohr 2006; Scheffel 2006). This book presents and discusses the technical concepts, the spectrum of clinical applications and the future developments of multi-slice CT in cardiac imaging based on the experience of internationally leading clinical institutions. It promises to serve as a comprehensive piece of literature that covers all aspects from the technical principles of CT acquisition and image evaluation all the way to clinical indications and potential pitfalls of multi-slice cardiac CT imaging. The first edition that appeared in early 2002 outlined the basic technical concepts and early clinical experience with one specific 4-slice CT scanner from a single vendor (SOMATOM Volume Zoom, Siemens, Germany), using special cardiac imaging test software (HeartView, Siemens, Germany) that had been evaluated in various recognized academic clinical institutions. Since the publication of the first edition multi-slice cardiac CT has attracted great interest among radiologists and cardiologists and advanced CT imaging products have become available from all major CT manufacturers based on common acquisition and reconstruction principles. The keen interest in the first edition of our book, combined with the extremely fast technical development in terms of both slices per rotation and rotation speed, as well as the increasing clinical acceptance of multislice cardiac CT in radiology and cardiology, have motivated us to publish this new and entirely reworked second edition. We received many highly constructive recommendations from readers, reviewers and clinical experts which have helped to further broaden the spectrum and improve the quality of this book and, as a result, we have tried to incorporate as many of these aspects as possible. In this second edition we discuss the technological principles of general purpose and cardiac multi-slice CT based on the new state-the-art CT scanners with simultaneous acquisition of at least 16 and up to 64 slices per rotation. On the basis of these technical principles we have put emphasis on the discussion of scan and examination protocols from 4- to 16- and 64-slice CT and incorporated an extensive analysis of drawbacks and advantages of the various technology levels for certain clinical applications. Efficient postprocessing of the acquired thin-slice image data has become an integral part

7 of successful cardiac CT examinations and we have therefore extended the relevant section of the first edition to give an extensive overview of the various available techniques, including a chapter dedicated to their clinical usefulness. A completely new section has been added to this second edition to provide the reader a comprehensive overview of the most recent clinical experience and recommendations. In this section world-renowned clinical experts from Europe and the US share their experience with the most relevant clinical applications and indications of multi-slice cardiac CT. The reader also has the opportunity to learn more about some initial hands-on experience by means of representative 64-slice case studies based on CT image data sets included on the attached CD-ROM. Although the editors and guest authors are most familiar with the equipment from one particular vendor and the related cardiac CT imaging software, the introduction to technical principles and the discussion of clinical applications is also valid for equipment from other manufacturers. With regard to system and hardware design concepts and scan protocols special attention has been paid to potential differences between currently available CT scanner products from the different CT vendors. To allow newcomers to the field and readers without extensive experience in CT imaging or cardiac diagnosis a quick ramp-up, we have included chapters that address the fundamental principles of CT, as well as an introduction to cardiac anatomy and the most relevant cardiac diseases. In the final section we discuss remaining limitations of the latest multi-slice CT scanners in cardiac imaging and present future directions in terms of scanner technology and clinical applications. In this section we will introduce, for the first time, the technical concept of and initial experiences with a new dual-source CT system which provides significant enhancements in terms of temporal resolution compared to conventional multi-slice CT scanners and which may soon represent the CT technology of choice for cardiac applications. Interdisciplinary collaboration between radiology and cardiology is particularly important for the successful implementation of this new method in a clinical environment and the editors would like to thank Dr. A. Knez, Dr. A. Leber, Dr. A. Becker and Prof. G. Steinbeck from the Department of Cardiology at the University of Munich, Klinikum Grosshadern, for their unflagging support. A global network of numerous world-leading institutions has been established for the early testing of new applications and protocols for multi-slice cardiac CT and for the evaluation of its use in clinical practice. The open exchange of experience and ideas has contributed substantially to the comprehensive spectrum of information included in this book. Thus, the editors would like to express their special thanks to the extraordinary support from this edition s guest authors, Dr. Roman Fischbach, Dr. Kai-Uwe Jürgens, Prof. Walter Heindel, Dr. Koen Nieman, Dr. Nico Mollet, Dr. Filippo Cademartiri, Prof. Pim de Feyter, Dr. Stephan Achenbach, Dr. Stephen Schröder, Dr. Axel Küttner, Dr. Andreas Kopp, Prof. Claus Claussen, Dr. Jean-Francois Paul, Dr. Steffen Fröhner, Dr. Jürgen Willmann, Dr. Bernd Wintersperger, Dr. Konstantin Nikoalou, Dr. Michael Poon, Dr. C. Learra and Dr. Uwe-Joseph Schöpf, for their extremely valuable contributions of outstanding Preface VII

8 VIII Preface quality. The editors would also like to thank Dr. Katharina Anders, Dr. Ullrich Baum, Prof. Werner Bautz (University of Erlangen), Dr. Joachim Wildberger, Dr. Andreas Mahnken, Prof. R. Günther, Prof. Matheijs Oudkerk (University of Groningen), Dr. Stephan Martinoff, Dr. Jörg Hausleiter (German Heart Center Munich), Prof. Schmidt, Prof. Kerber (Rhön-Klinikum, Bad Neustadt), Prof. Rick White (Cleveland Clinic), Dr. Cynthia McCollough, Dr. Joel Fletcher, Dr. David Hough (Mayo Clinic Rochester), Prof. Geoffrey Rubin, Prof. Gary Glazer (Stanford University), Dr. Udo Hofmann, Dr. Thomas Brady (MGH, Boston), Prof. Martine Remy-Jardin, Prof. Jaque Remy (University of Lille), Prof. Kunihiko Fukuda (Jikei University, Tokyo), Prof. Sato (Nihon University, Tokyo), Prof. Sim (Sarawak Heart Center, Kuching), Mrs. Karin Barthel, Mrs. Heike Theesen, Mrs. Sigi Scheuerer, Mr. Andreas Blaha, Mrs. Dominique Sandner, Mrs. Loke-Gie Haw, Dr. Karl Stierstdorfer, Dr. Herbert Bruder, Dr. Reiner Raupach, Dr. Lars Hofmann and Dr. Tobias Seyfarth (Siemens Medical Solutions) for their support and contributions to this work and to related clinical and technical studies. This book aims to highlight that multi-slice cardiac CT has arrived in clinical practice and has the potential to become a reliable and widely available tool for noninvasive cardiac and coronary diagnosis in day-to-day patient care. With this second edition of the book Multi-slice and Dual-source CT in Cardiac Imaging we hope to make a valuable and significant contribution to the education of radiologists, cardiologists, technologists and physicists on this new, upcoming and exciting clinical tool, covering a broad spectrum from comprehensive overviews of the basics for newcomers to the introduction of new imaging protocols using the latest technology and new clinical applications for experienced users and researchers. Forchheim, Beijing Munich Bernd M. Ohnesorge Thomas G. Flohr Christoph R. Becker Andreas Knez Maximilian F. Reiser Deanfield JE, Mason RP, Nissen SE, Williams BW (2001) Coronary artery disease: from managing risk factors to treating complications. Clin Cardiol 24[Suppl I Intn l] Windecker S et al (1999) Interventional cardiology in Europe Eur Heart J 20: Scheffel H, Alkadhi H, Leschka S, et al (2006) Diagnostic accuracy of dual-source CT coronary angiography: first experience in a high pre-test probability population without heart rate control. Eur Radiol (in press) Flohr T, McCollough C, Ohnesorge B, et al (2006) First performance evaluation of a dual source CT (DSCT) system. Eur Radiol 16:

9 Contents IX Contents 1 Introduction Bernd Ohnesorge Basic Principles of CT Imaging Established Imaging Modalities for Cardiac Imaging Invasive Imaging Non-invasive Imaging Clinical Goals for CT in the Diagnosis of Cardiac and Thoracic Diseases Coronary Artery Disease Other Cardiac Diseases Diseases of the Thoracic Vessels The History and Evolution of CT in Cardiac Imaging Principles and Applications of Electron-Beam CT Cardiac Imaging with Conventional Mechanical CT References Cardiac and Cardiothoracic Anatomy in CT Roman Fischbach Topography Standard Views Coronary Arteries and Veins Pericardium Cardiac Chambers Cardiac Valves Great Vessels References Multi-slice CT Technology Thomas Flohr and Bernd Ohnesorge Evolution from 1 to 64 Slices Principles of Multi-slice CT System Design

10 X Contents 3.3 Multi-slice CT Acquisition and Reconstruction for Body Imaging Definition of the Pitch The Cone-Angle Problem in Multi-slice CT Multi-slice Spiral Reconstruction Neglecting the Cone-Beam Geometry Multi-slice Spiral Reconstruction with Cone-Beam Algorithms References Principles of Multi-slice Cardiac CT Imaging Bernd Ohnesorge and Thomas Flohr Basic Performance Requirements for CT Imaging of the Heart CT Imaging with Optimized Temporal Resolution: The Principle of Half-Scan Reconstruction Prospectively ECG-Triggered Multi-slice CT Retrospectively ECG-Gated Multi-slice CT Multi-slice Cardiac Spiral Reconstruction ECG-Gated Multi-slice Spiral Acquisition Segmented Cardiac Reconstruction Algorithms Cardiac Cone-Beam Reconstruction Algorithms ECG-Gated Spiral Scanning with Increased Volume Speed Synchronization with the ECG and Cardiac Motion ECG-Based Phase Selection The Pros and Cons of ECG Gating and ECG Triggering Alternative Cardiac-Motion Gating Approaches Radiation Exposure Considerations Principles of Radiation Dose Measurement in CT Radiation Exposure for Selected Cardiac Examination Protocols Exposure Reduction with ECG-Gated Tube-Current Modulation Optimization for Different Patient Sizes Optimization of Contrast-to-Noise Ratio References Clinical Examination Protocols with 4- to 64-Slice CT Bernd Ohnesorge Quantification of Coronary Artery Calcification CT Angiography of the Cardiac Anatomy and Coronary Arteries Cardiac Function Imaging Cardiothoracic Examination Protocols References

11 Contents XI 6 Image Visualization and Post-processing Techniques Thomas Flohr and Bernd Ohnesorge Trans-axial Image Slices Multi-planar Reformation Maximum-Intensity Projection Volume-Rendering Technique Vessel Segmentation and Vessel Analysis Four-Dimensional Visualization and Functional Parameter Assessment Myocardial Perfusion Evaluation Quantification of Coronary Calcification References Clinical Indications 7.1 Current and Future Clinical Potential Christoph Becker and Andreas Knez Cardiac Multi-slice CT Technique Coronary Calcium Screening Coronary CT Angiography Non-coronary Applications References Risk Assessment with Coronary Artery Calcium Screening Roman Fischbach Introduction Methods of Coronary Artery Calcification Quantification Multi-slice CT Examination Technique Clinical Applications of Coronary Calcium Measurement Further Clinical Applications of Calcium Scanning Conclusion References Detection and Exclusion of Coronary Artery Stenosis Koen Nieman, N. Mollet, F. Cademartiri, and F. de Feyter Introduction Diagnostic Performance of 4-Slice CT Diagnostic Performance of 16-Slice CT Diagnostic Performance of 64-Slice CT

12 XII Contents Image Processing and Analysis Discussion References Assessment and Interpretation of Atherosclerotic Coronary Plaques Stephan Achenbach Clinical Background Clinical Concepts Visualization of Coronary Atherosclerotic Plaques Visualization of Non-calcified Plaques by Multi-slice CT Perspective References Coronary CT Angiography in Patients with Chest Pain Axel Küttner and Stephen Schröder Clinical Background Methods and Protocols Results in a Representative Patient Population Discussion References Evaluation of Coronary Artery Bypass Grafts Axel Küttner and Andreas Kopp Clinical Background Protocol to Assess Graft Patency and Native Vessels with Multi-slice CT Results in a Representative Patient Population Conclusion References Patency Control of Coronary Stents Koen Nieman, N. Mollet, F. Candemartiry, and F. de Feyter Introduction CT Imaging Characteristics of Stents Post-processing and Analysis In Vivo Coronary Stent Imaging Conclusion References

13 Contents XIII 7.8 Evaluation of the Coronary Anomaly, Fistula, Aneurysm, and Dissection Steffen Fröhner Introduction Anomalies of the Coronary Arteries Coronary Artery Fistulas Myocardial Bridges Coronary Aneurysms Coronary Dissection Coronary Vasculitis Conclusion References Diagnosis of Congenital Heart Disease in Adults and Children Jean-François Paul Introduction Technical Aspects and Imaging Protocols Clinical Indications Improvements with 64-Slice CT Conclusion References Evaluation of Ventricular Function Parameters Kai Uwe Jürgens and Roman Fischbach Introduction Determination of Cardiac Function Parameters with Multi-slice CT Data Acquisition and Image Reconstruction Image Analysis Limitations Clinical Considerations Summary and Outlook References Imaging and Diagnosis of Cardiac Valves Jürgen Willmann Introduction Technical Considerations Valvular Morphology Valvular Disease

14 XIV Contents Limitations Conclusion References Visualization of Cardiac Tumors and Masses Bernd Wintersperger Introduction Imaging Techniques Epidemiology of Cardiac Masses and Clinical Application of CT Conclusion References Imaging of the Pulmonary Veins in Patients with Atrial Fibrillation Michael Poon and C. Learra Introduction Pharmacological Treatment Options Non-pharmacological Treatment of Atrial Fibrillation: Catheter Ablation The Role of Imaging in the Era of Catheter Ablation of the Pulmonary Veins Multi-slice CT Imaging of the Pulmonary Veins and Left Atrium The Role of Multi-slice CT in Catheter Ablation of Afib Conclusions References Potential of Myocardial Perfusion and Viability Studies Konstantin Nikolaou and Bernd Wintersperger Introduction Principles of Myocardial Perfusion Assessment Technical Considerations of Multi-slice CT Study Data on Myocardial Perfusion Imaging Using Multi-slice CT Assessment of Myocardial Viability with Multi-Slice CT Conclusion References Cardiothoracic Multi-Slice CT in the Emergency Department Uwe-Joseph Schöpf ECG-Gated Multi-Slice CT Scanning of the Chest

15 Contents XV Patients with Equivocal Chest Pain in the Emergency Department Slice CT as a Triage Tool in the Emergency Department References Future Technical Developments in Cardiac CT Bernd Ohnesorge Limitations and Pitfalls with Today s Multi-slice CT Temporal Resolution Volume Coverage Spatial Resolution and Signal-to-Noise Ratio Radiation Exposure A Future for Electron-Beam CT? Future Possibilities with Area Detector CT New Frontiers with Dual-Source CT Dual-Source CT: System Concept and Design Dual-Source CT: Cardiac Scanning Principles and Techniques Dual-Source CT: System Performance Evaluation Dual-Source CT: Clinical Scan Protocols and Preliminary Clinical Results References Subject Index