Cardiovascular MR Manual

Transcription

1 Cardiovascular MR Manual

2 Sven Plein John P. Greenwood John P. Ridgway Cardiovascular MR Manual

3 Authors Sven Plein Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Department of Cardiology, G-Floor, Jubilee Wing, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX United Kingdom John P. Ridgway Department of Medical Physics and Engineering Leeds Teaching Hospitals NHS Trust Leeds General Infirmary Leeds LS1 3EX UK John P. Greenwood Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Department of Cardiology, G-Floor, Jubilee Wing, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX United Kingdom ISBN e-isbn DOI / Springer London Dordrecht Heidelberg New York British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Control Number: Springer-Verlag London Limited 2011 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 licenses 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. Cover design: estudiocalamar, Figueres/Berlin Printed on acid-free paper Springer is part of Springer Science+Business Media (

4 Foreword Cardiovascular magnetic resonance (CMR) has become an established imaging modality with an expanding range of clinical indications. While in the past the CMR imaging was available in only a few specialist centres, the use of CMR is now becoming much more widespread. All clinicians working in Cardiology or Imaging should therefore have a general understanding of the diagnostic information that can be obtained from CMR, the indications for referral as well as contraindications and limitations of the technique. For cardiologists and radiologists in particular, CMR will become a routine diagnostic tool and training curricula in Cardiology or Radiology will require a compulsory period of training in CMR. This book is conceived as a compact introductory text to CMR and as a practical guide for daily use. The book begins with a detailed didactic overview of the physics of magnetic resonance imaging a subject that many clinicians find difficult to understand, but one that is essential for the appropriate use of this technology, as it determines image quality and most appropriate use. We have taken a very practical approach to explaining MRI physics, cross-referencing consistently to the subsequent clinical chapters and showing how an understanding of basic MRI physics translates into generating better images. The second part of the book explains the practicalities of CMR from the referral to screening, set-up of the study and reporting. It then outlines the most commonly acquired v

5 vi Foreword image components used in CMR and explains with tips and tricks how the user can generate good quality images. The third part of the book gives details of how CMR is used in clinical practice. It covers the most common referrals for CMR imaging in a structured way with imaging protocols and case examples for each indication. Throughout the book, we have used graphs and tables as well as boxes that highlight important aspects. The emphasis of each chapter is on providing practical, hands-on information. We hope that this compendium will be a useful resource for clinicians wishing to learn the basics of CMR and a handy guide for everyday use in clinical practice. Sven Plein John P. Greenwood John P. Ridgway

6 Part I How Does CMR Work? 1 What s Inside the Magnet and Why? The Main Magnet The Gradient Coil Assembly Integral Radiofrequency (RF) Body Transmitter Coil Receiver Coil The MRI Environment The Examination Room and RF Shielding The Magnetic Fringe Field Hazard and the Controlled Area Active and Passive Magnetic Shielding Protons and Spins: The Origin of the MRI Signal MRI Images: What Are We Looking At? Proton Spin and Net Magnetization What Determines the Size of the Net Magnetization? Generating a Signal: RF Pulses and Echoes How Do We Generate a Signal? What Does the RF Pulse Do to the Magnetization? Longitudinal and Transverse Components of Magnetization vii

7 viii 4.4 Flip Angle and Common RF pulses Variable-Flip Angle RF Excitation Pulse RF Excitation Pulse RF Pulse (Refocusing Pulse) RF Pulse (Inversion Pulse) What Does the MRI Signal Look Like? Relaxation Times, Gradient Echoes, and Spin Echoes. 5.1 Relaxation: What Happens After the RF Excitation Pulse? What is T1 Relaxation? Transverse Relaxation and MRI Signal Decay What is T2 Relaxation? What is T2* Relaxation? MR Echoes Gradient Echoes Spin Echoes Making an Image: Locating and Encoding Signals in Space Selecting an Image Slice Encoding the MR Signal Within the Slice Phase Encoding Frequency Encoding How is the Frequency-Encoded Signal Decoded? How do we make sure that the Gradients we apply for Imaging don t destroy the signal?. 6.7 Why isn t a Single Phase and Frequency Encoded Signal enough to Reconstruct an Image? Field of View in the Phase Encoding Direction Phase Encoding, Image Matrix, and Acquisition Time

8 ix 7 Image Space and k-space Imaging Parameters and Image Attributes Spatial Resolution and Image Acquisition Time Noise and Signal-to-Noise Ratio Factors That Determine Image Quality Intrinsic Signal Amplitude Signal Averaging SNR and Receiver Bandwidth Imaging Parameters: Practical Examples D and 3D Imaging Improving SNR with Surface Coils and Array Coils Pulse Sequences and Image Contrast Dependence of the MR Signal on TR and TE Image Contrast and Weighting Long TR and Short TE Short TR, Short TE Long TR, Long TE Short TR, Long TE Gradient Echo Versus Spin Echo Black Blood Versus Bright Blood Imaging Black Blood (Spin Echo Pulse Sequence) Black Blood Double Inversion Preparation Pulses Bright Blood (Gradient Echo Pulse Sequence) Dealing with Cardiac Motion: How Do We Image the Beating Heart? Still Imaging Cine Imaging Triggering Versus Gating for Cine Imaging

9 x Prospective Versus Retrospective ECG Gating Spoiled Gradient Echo versus bssfp Dealing with Respiratory Motion Respiratory Compensation (Respiratory Gating) Respiratory Gating using Navigator Echoes Fast Imaging: How Do We Speed Up the Image Acquisition? Turbo (or Fast) Spin Echo Turbo (or Fast) Gradient Echo Echo Planar-Imaging (EPI) Reducing the Total Number of Phase Encoding Steps Acquired for Each Image Parallel Imaging Special Pulse Sequences for Cardiac Imaging Selective Tissue Saturation Frequency Selective Fat Suppression Pros and Cons of Frequency Selective Fat Suppression (cf. STIR) STIR and Turbo STIR Pros and Cons of STIR (cf. Frequency Selective Fat Suppression) Black Blood FSE/TSE (Double Inversion) Black Blood turbostir (Triple Inversion Recovery) Inversion Recovery Fast/Turbo Gradient Echo Navigator-Gated 3D Fast/Turbo Gradient Echo (Coronary Artery Imaging) Key Features of a Navigator-Gated 3D Coronary Artery Imaging Sequence Cine Gradient Echo Velocity Encoded Cine Gradient Echo (Velocity Mapping) Myocardial Tagging (Binomial Pulses) Saturation Recovery, Single-Shot Fast Gradient Echo for Dynamic, Contrast-Enhanced Myocardial Perfusion Imaging

10 xi 17 Common Artifacts Image Aliasing Aliasing Artifacts with Parallel Imaging Ghosting Artifacts from Motion (Respiratory) Ghosting Artifacts from Motion (Pulsatile Flow) Flow-Related Signal Loss and Flow Jets Chemical Shift Artifact Magnetic Susceptibility Artifacts Metallic Artifact Radiofrequency Interference Artifacts Part II How CMR is Performed 18 The Basics of a CMR Study The Referral Indications for CMR Contraindications/Safety Screening Contraindications to CMR Scanning Setting Up a CMR Study Equipment ECG Signals Patient Preparation Commencing the Scan References Components of CMR Protocols Introduction Localizing Images and Simple Planning Interactive Planning Anatomical and Morphological Imaging T1-Weighted (Black Blood) Imaging T2-Weighted (Black Blood) Imaging T2* Relaxometry Cine Imaging (Including Real-Time Cine Imaging) Real-Time Cine Imaging Quantitation

11 xii Myocardial Tagging Phase Contrast Velocity Encoding Contrast-Enhanced MR Angiography (Excluding Coronary Arteries) Myocardial Perfusion CMR Reproducible Planning of Three Short Axis Slices Dark Rim Artifact Interpretation of CMR Myocardial Perfusion Images Early and Late Gadolinium Enhancement Protocol for Early and Late Gadolinium Enhancement Imaging Coronary Artery Imaging Whole Heart Technique Targeted Technique Anatomy by CMR Cross-sectional Anatomy Customized Views Comparison with Other Imaging Modalities The CMR Report A Structured Approach to Reporting a CMR Study The Report Reference Part III Clinical Indications for CMR Imaging 22 Diseases of the aorta Introduction CMR versus Other Imaging Modalities CMR in the Assessment of Aortic Atherosclerosis and Dissection Acute Intramural Hematoma Penetrating Atherosclerotic Ulcer Aortic Dissection Aortic Aneurysm

12 23 Cardiomyopathies General Overview Dilated Cardiomyopathy (DCM) Introduction CMR versus Other Imaging Modalities in DCM Findings on CMR Differential Diagnosis Case Example Hypertrophic Cardiomyopathy (HCM) Introduction CMR versus Other Imaging Modalities Findings on CMR Differential Diagnosis Case Example Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) Introduction CMR versus Other Imaging Modalities Findings on CMR Differential Diagnosis Case Example Left Ventricular Non-Compaction Cardiomyopathy (LVNC) Introduction CMR versus Other Imaging Modalities Role of CMR in LVNC Findings on CMR Differential Diagnosis Case Example Inflammatory Diseases: Myocarditis Introduction CMR versus Other Imaging Modalities Findings on CMR Differential Diagnosis Case Example Inflammatory Diseases: Sarcoidosis Introduction Findings on CMR xiii

13 xiv Differential Diagnosis Case Example Inflammatory Diseases: Vasculitis (Churg Strauss Syndrome) Introduction Findings on CMR Differential Diagnosis Case Example Infiltrative/Storage Diseases: Amyloidosis Introduction Findings on CMR Differential Diagnosis Case Example Infiltrative/Storage Diseases: Siderotic Cardiomyopathy Introduction CMR versus Other Imaging Modalities Findings on CMR Differential Diagnosis Case Example Tako-Tsubo Cardiomyopathy Introduction CMR versus Other Imaging Modalities Findings on CMR Differential Diagnosis Case Example References Pericardial Disease Pericardial Effusion Introduction CMR versus Other Imaging Modalities Findings on CMR Case Example Constrictive Pericarditis Introduction CMR versus Other Imaging Modalities Findings on CMR Case Example

14 xv Pericardial Tumors Introduction CMR versus Other Imaging Modalities Findings on CMR Congenital Abnormalities of the Pericardium Introduction CMR versus Other Imaging Modalities Findings on CMR Case Example Cardiac Masses Introduction Benign Cardiac Tumors Myxoma Lipoma Papillary Fibroelastoma Fibroma Rhabdomyoma Hemangioma Malignant Cardiac Tumors Sarcoma Lymphoma Metastatic Tumors Other Masses and Tumors Thrombus Cysts Pseudotumors Further Readings Valvular Heart Disease Introduction CMR Versus Other Imaging Modalities Congenital Regurgitation Stenosis Prosthetic Valves Vegetations Paravalvular Abscesses

15 xvi 27 Ischemic Heart Disease Introduction Stress Myocardial Perfusion Imaging for the Detection of Myocardial Ischemia Introduction Myocardial Perfusion CMR Versus Other Imaging Modalities Diagnostic Performance Prognostic Performance How to Perform a Myocardial Perfusion CMR Study Safety Considerations Analysis of CMR Perfusion Images Case Examples CMR Stress Wall Motion Imaging for the Detection of IHD Introduction CMR Versus Other Imaging Modalities Diagnostic Performance Prognostic Performance Method Safety Considerations Analysis Case Example Which Stress Modality Should I Choose? CMR for Assessment of Viability Introduction CMR Versus Other Imaging Modalities CMR Methods for Viability Assessment Case Examples CMR in Acute Coronary Syndromes Introduction CMR Versus Other Imaging Modalities Methods Case Examples

16 xvii 27.6 Positive Cardiac Enzymes and Normal Coronary Arteries Example Case Potential Future Developments Hardware Development Software Development New Methods References Basic Adult Congenital Heart Disease (ACHD) Introduction CMR Versus Other Imaging Modalities Coarctation of the Aorta Tetralogy of Fallot Transposition of the Great Arteries Coronary Anomalies Partial Anomalous Pulmonary Venous Return (PAPVR) Summary Pulmonary Vein Assessment Introduction CMR Versus Other Imaging Modalities CMR Protocol and Findings CMR Analysis Interventional Cardiovascular Magnetic Resonance Imaging Introduction Interventional MRI Systems XMR Facility Design MR Visualization Strategies Performing XMR Procedures Physiological Information Early Experiences Future Perspectives References Index

17 Contributors Dr. Sven Plein, MD, PhD Senior Lecturer & Consultant Cardiologist University of Leeds, Leeds, UK Dr. John P. Greenwood, MBChB, PhD, MRCP(UK) Senior Lecturer & Consultant Cardiologist University of Leeds, Leeds, UK Dr. John P. Ridgway, PhD Department of Medical Physics & Engineering, Leeds Teaching Hospitals NHS Trust Leeds General Infirmary, Leeds, UK Dr. Adam Mather Research Fellow, University of Leeds, Leeds, UK Dr. Neil Maredia Research Fellow, University of Leeds, Leeds, UK Dr. Charles Peebles, MBBS, MRCP, FRCR Consultant Cardiothoracic Radiologist, Cardiothoracic Radiology Department, Southampton General Hospital, Southampton, UK Dr. Daniel Messroghli, MD Research fellow, Congenital Heart Defects and Pediatric Cardiology, German Heart Institute, Berlin, Germany xix

18 xx Contributors Dr. Andrew M. Crean Associate Professor Peter Munk Cardiac Center (Cardiac Imaging), Toronto General Hospital, Toronto ON, Canada Dr. Amedeo Chiribiri Clinical Research Fellow Division of Imaging Sciences, King s College London, St Thomas Hospital London, London, UK Dr. Gerald F. Greil Consultant Paediatric Cardiologist/Senior Clinical Lecturer, Division of Imaging Sciences, King s College London, St. Thomas Hospital, London, UK Dr. Tarique M. Hussain Research Fellow, Division of Imaging Sciences, King s College London, St. Thomas Hospital, London, UK Dr. Kawal Rhode Lecturer, Division of Imaging Sciences, King s College London, St. Thomas Hospital, London, UK