Cardiovascular Magnetic Resonance Update E-Book

J. Schwitter

• Herausgeber: Juerg Schwitter
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 415

Veröffentlichungsjahr: 2023

Beschreibung

For the general cardiologist a compact and up-to-date indications list for CMR exams with illustrative examples is provided covering the entire field of cardiology with 16 chapters. For the CMR expert updated state-of-the-art CMR protocols are given.

Leseprobe

CMR Update

3rd Edition

Impressum

Copyright © 2020 by J. Schwitter, MD, FESC. All rights reserved. No part of this publication with the title CMR Update may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any other information storage retrieval system, without permission in writing from the publisher. The opinions expressed in the “CMR Update” are those of the contributors and the editor. The ultimate responsibility lies with the prescribing physician to determine drug or contrast medium dosages and the best diagnostic or treatment strategies for the patient. The publisher is not responsible (as a matter of product liability, negligence or otherwise) for an injury resulting from any material contained herein. The published material relates to general principles of medical care and should not be used as specific instruction for individual patients. The reader is advised to check the current product information provided by the manufacturer of each drug or contrast medium to be administered, in order to ascertain any change in drug or contrast medium dosage, method of administration, or contraindications. Mention of any product in this book should not be construed as an endorsement by the contributors or editor. Clinicians are encouraged to contact the manufacturer(s) of these product(s) with any questions about their specific features or limitations. The editor and publisher of “CMR Update” is Juerg Schwitter, MD, FESC. Lausanne, Switzerland. Email: [email protected]; on the internet: www.herz-mri.ch.

ISBN: 978-3-9875-6338-6

The publisher has made every effort to trace copyright holders for borrowed material. If he has inadvertently overlooked any, he will be pleased to make the necessary arrangements at the first opportunity.

Design: Bruno Lazzeri and Juerg Schwitter

Chapters and Authors

1 Volumes, Function, and Deformation:

Left and Right Ventricles and Atria

J. Schwitter / E. Nagel

2 Safety of MRI

R. Luechinger / O. Bruder / J. Schwitter

3 Coronary Artery Disease (CAD): Ischemia – Perfusion

J. Schwitter / M. Lombardi

4 CAD: Ischemia – Stress Dobutamine-CMR

E. Nagel / O. Bruder

5 Coronary Artery Disease: Infarction and Heart Failure

R. Nijveldt / C. Bucciarelli-Ducci / A.C. van Rossum

6 CAD: Coronary MR-angiography

E. Nagel / J. Schwitter

7 Heart Valve Disease

B. L. Gerber MD / P. Monney / J. Schwitter

8 Congenital Heart Disease in Adults

V. Muthurangu / J. Schwitter

9 Cardiomyopathies

J. Schulz-Menger / H. Mahrholdt / D. Pennell / M. Lombardi /

A. Pepe / J-P. Carpenter / S. K. Prasad / J. Schwitter

10 CMR in Myocarditis

H. Mahrholdt / S. Greulich / J. Schulz-Menger

11 Pericardial Diseases

M. Francone / J. Bogaert / J. Schwitter

12 Cardiovascular Magnetic Resonance in Electrophysiology

I. Paetsch / C. Jahnke / J. Schwitter / G. Hindricks

13 Tumors and Masses of the Heart and of the Pericardium

M. Lombardi / C. Bucciarelli-Ducci / H. Frank

14 MR-Angiography: Great Vessels

S. Mavrogeni / J. Schwitter

15 MR-Angiography: Peripheral Vessels

S. Mavrogeni / J. Schwitter

16 Economy – Cost Effectiveness

T. Murphy / J. Schwitter / S. Petersen

Foreword and dedication

Foreword

The first ECG gated magnetic resonance (MR) images of the heart were published about 35 years ago. These early multi-slice MR images required an imaging time of 6 to 10 mins. and were used to evaluate cardiac morphology. However, it was soon recognized that MR imaging parameters could be manipulated, and paramagnetic contrast utilized to attain some myocardial tissue characterization, mostly based upon water content and access of contrast media to water in the tissue.

The early clinical indications for cardiovascular MR (CMR) were based upon assessment of morphology and were very limited in relation to other pre-existing cardiac noninvasive imaging techniques. The clinical uses of CMR have expanded rapidly up to the current time. This CMR booklet, shows the multitude of insights into cardiovascular disease now provided by CMR: morphology, function, blood flow, and tissue characterization. It indicates that CMR has cogent applicability for all types of cardiovascular diseases and provides precise and highly reproducible quantification of morphology, function, and blood flow.

It is recognized that CMR remains a technically complicated imaging technique. Moreover, the capabilities and diverse clinical applications are less familiar to cardiovascular diagnosticians. This booklet provides a concise guideline into the accepted clinical application of CMR, appropriate protocols for specific applications, and vivid case examples of the information provided by the CMR examination. It should greatly contribute to the goal of rendering CMR as familiar to cardiovascular physicians as other imaging modalities.

Charles B. Higgins, MD, FACC, FAHA

Former President, Society of Cardiovascular Magnetic Resonance

Dedication

To my family who supported me with motivation and patience over more than 25 years, and all friends and colleagues, who worked in the field of CMR with the aim to improve patient care.

Juerg Schwitter, MD, FESC

Former Chairman, EuroCMR of the European Society of Cardiology

Authors’ Affiliations

Jan Bogaert, MD, PhD

Department of Radiology

UZ Leuven

Leuven, Belgium

Oliver Bruder, MD

Associate Professor of Medicine

Contilia Heart and Vascular Center

Elisabeth Hospital Essen

Director Department of

Cardiology and Angiology

Essen, Germany

Chiara Bucciarelli-Ducci, MD, PhD

Consultant Senior Lecturer in Cardiology

and non-invasive Imaging

Co-Director, Clinical Research and Imaging Centre Bristol

Bristol Heart Institute

University of Bristol and University

Hospitals Bristol NHS Foundation Trust

CEO of the SCMR

Bristol, United Kingdom

John-Paul Carpenter, MD

Clinical Lead for Cardiology

Poole Hospital NHS Foundation Trust

Poole, United Kingdom

Marco Francone, MD, PhD

Department of Radiological,

Oncological and Pathological Sciences

Sapienza University of Rome,

Policlinico Umberto I

Rome, Italy

Herbert Frank, MD

Professor of Cardiology

Department of Internal Medicine

Landeskrankenhaus Tulln,

Donauklinikum

Former Chairman WG EuroCMR of ESC

Tulln, Austria

Bernhard L. M. Gerber, MD, PhD

Division of Cardiology

Department of Cardiovascular Diseases

Cliniques Universitaires St. Luc UCL

Woluwe St. Lambert, Belgium

Simon Greulich, MD

Private Docent, Cardiology

Deutsches Herzkompetenz Zentrum

University Hospital Tübingen

Tübingen, Germany

Gerhard Hindricks, MD, PhD

Professor of Cardiology

Chair Department of Electrophysiology

Heart Center Leipzig at University of Leipzig

Former President EHRA of ESC

Leipzig, Germany

Cosima Jahnke, MD

Professor of Cardiology

CMR Unit for Diagnostic and Interventional Procedures

Department of Electrophysiology Heart

Center Leipzig at University of Leipzig

Leipzig, Germany

Massimo Lombardi, MD

Multimodality Cardiac Imaging Section

IRCCS Policlinico San Donato

San Donato Milanese

Milan, Italy

Roger Luechinger, PhD

Institute for Biomedical Engineering

University and ETH Zurich

Zurich, Switzerland

Heiko Mahrholdt, MD

Professor of Cardiology

Consultant Senior Lecturer in Cardiology

Head of Cardiovascular MRI

Robert-Bosch Medical Center

Former Chairman WG EuroCMR of ESC

Stuttgart, Germany

Sophie Mavrogeni, MD, PhD

Professor of Cardiology

Onassis Cardiac Surgery Center

Athens, Greece

Pierre Monney, MD

University Hospital Lausanne, CHUV

Division of Cardiology and Cardiac MR Center

Lausanne, Switzerland

Theodore Murphy, MD

Cardiology Imaging Fellow

Blackrock Clinic

Dublin, Ireland

Vivek Muthurangu, MD

Professor of cardiovascular imaging and physics

University College London

Great Ormond Street Hospital

London, United Kingdom

Eike Nagel, MD, PhD

Professor of Cardiology

Director Institute for Experimental

and Translational CV Imaging

DZHK Centre for Cardiovascular Imaging

Head of Interdisciplinary CV Imaging

University Hospital Frankfurt / Main

Frankfurt, Germany

Robin Nijveldt, MD, PhD

Professor of Cardiovascular Imaging

Radboud University Medical Center

Department of Cardiology

Nijmegen, The Netherlands

Ingo Paetsch, MD

Professor of Cardiology

CMR Unit for Diagnostic and Interventional Procedures

Department of Electrophysiology

Heart Center Leipzig at University of Leipzig

Leipzig, Germany

Dudley Pennell, MD

Professor of Cardiology

National Heart & Lung Institute, Imperial College

Director, CMR Unit

Lead, Non-Invasive Cardiology

Royal Brompton Hospital

Former Chairman WG EuroCMR of ESC

London, United Kingdom

Alessia Pepe, MD, PhD

Cardiologist and Radiologist

Magnetic Resonance Imaging Unit

Fondazione G. Monasterio C.N.R.

Regione Toscana

Pisa, Italy

Steffen E. Petersen, MD, PhD

Professor of Cardiovascular Medicine

Honorary Consultant Cardiologist

Co-Director for Research, CV Clinical Board,

Barts Health NHS Trust

Centre Lead for Advanced CV Imaging

William Harvey Research Institute

NIHR Barts Biomedical Research Centre

Vice Chair CMR section of EACVI of ESC

London, United Kingdom

Sanjay K. Prasad, MD

Professor of Cardiology

Cardiovascular MR Unit

Royal Brompton Hospital

London, United Kingdom

Jeanette Schulz-Menger, MD

Professor and Head Cardiac MRI Team

Franz-Volhard Clinic

Charité University Berlin

Helios-Klinikum Berlin

Berlin, Germany

Juerg Schwitter, MD

Professor of Cardiology

Director of the CMR Center

University and University

Hospital Lausanne

Former Chairman WG EuroCMR of ESC

Lausanne, Switzerland

Albert van Rossum, MD, PhD

Professor of Cardiology

Chair Department of Cardiology

Location VU University Medical Center

Amsterdam

Vice-Chair Division 3,

Heart Center, location

Amsterdam University Medical Center

Founder and first Chairman of the

WG EuroCMR of the ESC

Amsterdam, the Netherlands

Publisher

Juerg Schwitter, MD

Professor of Cardiology

Director of the CMR Center

University and University

Hospital Lausanne

Former Chairman WG EuroCMR of ESC

Lausanne, Switzerland

Chapter 1. Volumes, Function, and Deformation: Left and Right Ventricles and Atria

J. Schwitter, MD,Lausanne, Switzerland

E. Nagel, MD, PhD, Frankfurt, Gemany

Indications: General

Regular component of most CMR studies

In particular:

● Suspected Cardiomyopathy (CMP)

. - hypertrophic CMP

.- dilated CMP

.- restrictive CMP

. - Arrhythmogenic right ventricular cardiomyopathy (ARVC)

. - unspecified CMP

● Valvular heart disease

. - Follow-up of disease progression

● Suspected or known coronary artery disease (CAD)

● Chronic or acute heart failure (HF)

. - define etiology of HF

. - in case of inadequate echo window

● Hypertensive heart disease - left ventricle (LV)

● Right ventricle (RV)

. - Fallot Tetralogy and other congenital heart diseases

. - RV hypertrophy: e.g. in pulmonary hypertension

. - ARVC

● Chemotherapy-induced cardiotoxicity

. - Patients during chemotherapy when echocardiography yields borderline results,1 e.g. with EF 50-59%2

!Sternal wires/clips after cardiac surgery and coronary stents do not interfere with CMR (for details see specific chapters)

! Patient should be able to hold his/her breath for 5-7 seconds*

! Limited diagnostic performance with frequent extrasystoles (>10/min) and with atrial fibrillation*

* Real time techniques are increasingly available for non-breath-hold imaging or severe arrhythmia3

Contraindications:

See general contraindications for CMR (Chapter 2: Safety of CMR)

Established evidence - Major CMR studies

Reproducibility and validation: CMR cine imaging is excellently validated and highly reproducible for LV and RV volumes and function due to the superb image quality (using steady state free precession, SSFP techniques).4 Diagnostic quality for LV/RV function assessment was achieved in >98% of studies (n=27’781).5 Repeated studies (performed by different operators) yield variabilities and 95% confidence intervals as follows:6

LEVDV: 4.2% (-1.26 to 9.6%); LVESV: 6.2% (-4.0 to 16.5%)

LVEF: 3.0% (-1.7 to 7.6%; LV-Mass: 4.2% (-2.2 to 10.7%)

Normal Ventricular Structure and Function by Age and Gender7

S.E. Petersen et al. J. Cardiovasc. Magn. Reson. 2017, reprinted by permission of Taylor & Francis Ltd (www.tandf.co.uk/journals)

Table 1: Steady state free precession (SSFP) acquisitions were performed in 800 healthy subjects and 3 age groups were analyzed (45-54 / 55-64 / 65-74 years). Normal range: 95% confidence interval for all age groups. Borderline: includes the 95% confidence interval of at least 1 age group. Abnormal (=outside borderline): outside the 95% confidence interval of all age groups.

Most basal slice of the LV was selected when at least 50% of LV blood pool was surrounded by myocardium. Long-axis cines were not considered for LV volume and function assessment.

Dependence on age

LV volumes decrease slightly with age for both gender (<10% over 30 years’ time period). LVEF stays stable. LV mass decreases in men (<5% over 30 years). RV volumes decrease slightly in men (<10% over 30 years), while RV EF increases slightly in women (<5% over 30 years).

! Changes of parameters (volumes, mass, function) over time in an individual patient are as important for the assessment of course of disease as absolute parameters relative to the normal range.

Normal Atrial Structure and Function by Age and Gender7

Table 2: Steady state free precession (SSFP) acquisitions were performed in 795 healthy subjects and 3 age groups were analyzed (45-54 / 55-64 / 65-74 years). LA values are calculated by the biplane area-length method. Asterisk: The RA values are measured on the 4 chamber view only. Normal range: 95% confidence interval for all age groups. Borderline: includes the 95% confidence interval of at least 1 age group. Abnormal (=outside borderline): outside the 95% confidence interval of all age groups.

Strain

Strain quantification based on feature tracking can be extracted from standard SSFP cine images. While strain is strongly superior to EF for echocardiography due to its inherent limitation of adequately visualising all parts of the ventricle in most patients, the additional value of strain for CMR is less clear. There is an increasing body of evidence demonstrating a strong prognostic power of strain measurements, which may be beyond EF and volumes. Its relation to fibrosis imaging with LGE or T1-mapping needs to be established.

● Strain is slightly more pronounced in females and some reports demonstrate a reduction with age.

● Strain seems to be independent of field strength

● Results are highly dependent on the post-processing technique used

● Global longitudinal strain is relatively robust

● CMR strain values are dominated by the subendocardial motion (even if endo- and epicardial contours are used) due to the stronger features of the endocardium.

Figure 1: Basic principle of feature tracking: The displacement of features detected mainly on the endocardium is followed over time. reprinted from reference G. Pedrizzetti et al. J Cardiovasc Magn Reson. 2016;18:51,3 with permission by Creative Commons (creativecommons.org/licenses/by/4.0)

Reproducibility and use in routine

● Typically, the coefficient of variation for intra- and interobserver variability is <10% for global longitudinal strain GLS (acceptable for clinical use)

● CV is slightly worse for global circumferential strain GCS (borderline acceptable for clinical use)

● CV is >10% for segmental LV strain, RV strain or atrial strain (not acceptable for clinical use)8-11

Figure 2 above shows normal values for global circumferential strain (GCS), global longitudinal strain (GLS), and global radial strain (GRS). Error bars are ± 1SD. Only studies with >100 participants are considered8, 9, 12, 13 yielding a total of 545 subjects plus one meta-analysis.10 (endo): strain is derived from the endocardial contours, (myo): strain is derived from both, endocardial and epicardial contours.

Clinical results

● Feature tracking has demonstrated superior prognostic value in comparison to LV ejection fraction and infarct size early after reperfused myocardial infarction,14 however, generalizability of these results is debated.

● Increasing body of evidence demonstrates superior prognostic value in ischemic15 and non-ischemic cardiomyopathies16

Prognosis of LV remodeling and LV hypertrophy on occurrence of ischemic heart disease, stroke, and heart failure.17

In the MESA (Multi-Ethnic Study of Atherosclerosis), 5004 subjects (age 45–85 y) free of clinically apparent cardiovascular disease were followed-up for a mean of 5.2 years.17 Absolute event rate (development of CAD, HF, stroke: n=216) in this asymptomatic population was low: i.e. 0.8%/year.

A LV mass/volume ratio of 1.3-3.0 predicted a 2.3-fold higher risk for the development of CAD than a ratio <1.0 (see Figure 2A to the right).

A LV mass/volume ratio of 1.3-3.0 predicted an 11-fold higher risk for stroke than a ratio <1.0 (see Figure 2B to the right).

The presence of a LVH (mass above the 95%-CI of normals, see also Tables) predicted an approximately 9-fold higher risk for HF development than a LV mass below the 50th percentile (see Figure 2C to the right). Figure 3 from Bluemke et al.17 with permission of the American College of Cardiology and Elsevier.

Prognostic information of LA structure and function on occurrence of CVD in diabetic patients.18

Figure 4. In the MESA (Multi-Ethnic Study of Atherosclerosis), 536 diabetic subjects (age 64±9 years) free of cardiovascular disease (CVD) were followed-up for a mean of 11.4 years for incident CVD (=MI, resuscitated cardiac arrest, angina, stroke, heart failure, and AF: 141 patients, 2.3%/year). CVD was correlated with LA parameters (calculated by the area-length method).

Figure 5. Definitions of LA function: (I) corresponds to passive LV filling (passive LA EF), (II) corresponds to active LV filling (active LA EF), and (III) corresponds to overall LA emptying (= total LA EF) (modified of Vardoulis et al, JCMR 2015)19

Patient preparation

● Instruction of patient: regarding safety, contraindications, risks (see Chapter 2)

● ECG placement for triggering (shave and clean skin)

● Avoid loops of ECG cables, check for firm contact between electrodes and cables

● Begin of scanning: Test of ECG triggering, if unreliable replace electrodes (re-clean skin)

● Body transmit and phase-array receive coils

Patient monitoring

● Heart rate (HR) and blood pressure (BP) should be documented to allow for interpretation of functional parameters (e.g. global ejection fraction, valve pathologies, etc.)

Scanning Protocol - Data acquisition

● Localizer in sagital plane (see Fig. 6) to get approximated horizontal long axis view (Fig. 7). In addition, coronal and axial localizers may be acquired.

● Approximated horizontal long axis view (see Fig. 7) to get vertical long axis (VLA) view (Fig. 8)

● Vertical long axis (VLA) view (Fig. 8) to get true 4 chamber view (4-CH) (Fig. 9)

● True 4 chamber view (4-CH) (Fig. 9)

. - planned on VLA (see Figure) or on “combined” view of sagital/ coronal/ axial localizers

● Stack of short axis (SA) slices covering the entire LV and RV

. - planned on the HLA at end-diastole to cover entire LV

● Slice thickness is 6-10 mm, gap 0-2 mm

● Temporal and spatial resolution:

. - 1-2 mm x 1-2 mm in plane, temporal: 40-60 ms

. - adjust resolutions to fit acquisitions into breath-holds

● Apply parallel imaging approaches to speed-up the examination

● True 4-CH might also be planned on a basal short-axis view (see Fig. 10)

● 3-chamber view (3-CH, Fig. 11) on the far right is planned on a basal short axis view (far left) together with a 4-CH view (middle).

Data analysis

● LV assessment:

● For LV end-diastolic and end-systolic volumes, define

. - end-diastole: typically first image of the cine acquisition

. - end-systole: aortic valve closure or mitral valve opening, as a rule of thumb: systole is smallest cavity size during the cardiac cycle

● Delineate endocardial and epicardial borders at end-diastole and end-systole (Fig. 12 below)

● Define the base of the LV at end-diastole (left column) and end-systole (right column):The LV base is “shifted” towards the apex during systole (typically by 1-2 slices, if LV systolic function is normal, i.e., in this example, no contours on the most basal slice in systole)

● RV assessment:

● Proceed as for the LV (see Fig. 12 above)

● Alternatively, RV volumes may be determined on axial cine acquisitions, which might be less problematic to determine the position of the base of the RV at end-diastole and end-systole. However, partial volume artefacts might be increased with axial slices in the region of the RV inferior wall.

● Report whether papillary muscles are included or excluded in the volume and mass measurement.

This protocol is in line with the protocols as recommended by the SCMR.20

CMR Tagging For Functional Assessment

Indications:

● Regional function assessment with visual analysis of tagging pattern

● Pericardial constriction visual analysis of free motion of myocardium versus pericardium. See for example chapter 11

● Evaluation of myocardium and pericardium involvement in patients with cardiac tumors and metastases with visual analysis of tagging pattern

Contraindications:

● see general contraindications for CMR

CMR Tagging Techniques21 - Acquisition

● For myocardial tagging, radiofrequency and gradient pulses are applied at the R-wave of the ECG to saturate or tag the tissue magnetization in a stripe or grid pattern (non-selective radio-frequency pulses separated by spatial modulation of magnetization [SPAMM]). Alternative technologies include DANTE (Delays Alternating with Nutations for Tailored Excitations) and CSPAMM [Complementary SPAMM]). As the heart contracts the deformation of the stripe or grid pattern reveals intramyocardial deformation.

● Standard tagging sequences for line and grid tagging are available on most vendor platforms

● Tagging signals fade over the cardiac cycle requiring specific approaches for assessing diastolic function (e.g. CSPAMM, diastolic tagging as shown in Figure 13).

Figure 13. The numbers in the lower right corners give the cardiac phase of acquisition. With conventional SPAMM (top row) the tagging is faded at end-diastole, whereas persistence is obtained with CSPAMM. In addition, CSPAMM takes 3D-deformation of the heart into account, i.e. in a short-axis orientation, the through-plane motion of the imaged plane during systole is corrected for as the tags of the moving slice are projected into one plane.

● Like breath-hold cine CMR, tagged cine images are generally acquired via an ECG-gated segmented method, requiring 12 to 16 heartbeats during suspended respiration.

● For more sophisticated analysis, tagged long-axis images or 3D tagged data sets can also be acquired.22

Tagging data analyses and applications

● Conventional analysis of tagged images requires computer-assisted detection of the epicardial border, endocardial border, and tag lines. Semi-automatic techniques generally require some extent of manual correction.

● After border and tag detection, the computation of myocardial strain, twist, torsion and other strains associated with tag deformation is performed automatically.

● Analysis of tagged images via the Harmonic Phase (HARP) method eliminates the need for conventional (manual) tag analysis and provides rapid strain analysis of tagged MR images.23 Filters used by HARP can reduce the spatial resolution.24

● Tagging data were also obtained in a multicenter trial in patients with MR-conditional pacemakers to demonstrate pacing-induced LV intraventricular dyssynchrony.25

CMR-based alternative methods to assess tissue deformation

Velocity-encoded phase contrast of myocardium

Instantaneous velocity is measured by creating transverse magnetization, applying bipolar velocity-encoding gradients, and detecting phase shifts that are linearly proportional to velocity. The successive instantaneous velocities can be interpreted in a manner analogous to tissue Doppler echocardiography or can be used to estimate displacements, strains, and strain rates.

Figure 14 to above is an example for a phase-contrast acquisition in a horizontal long axis orientation.

Displacement encoding with stimulated echoes (DENSE)

The DENSE technique has some of the advantageous properties of both, myocardial tagging and velocity-encoded imaging, leading to high accuracy, high spatial resolution, inherent tissue tracking without tag detection, and straightforward strain analysis.26In a manner similar to conventional myocardial tagging, DENSE tags the signal upon detection of the R-wave at end-diastole and samples the displacement-encoded signal later in the cardiac cycle, thereby avoiding the error accumulation problem inherent to velocity-encoded imaging. However, instead of encoding displacement information into the amplitude of the signal like tagging, the displacement information is encoded into the phase of the signal. Thus, DENSE has the property that displacement relative to the end-diastolic position, not instantaneous velocity, is measured in the signal phase. Also, because displacement is measured via the phase, pixel-wise spatial resolution and inherent tissue tracking are achieved. In theory, DENSE is not much different than HARP analysis, which applies the same principles to analyse tagged images. However, in practice, the hallmark of DENSE has been much higher spatial resolution realized through prospective pulse sequence design rather than filtering the raw data acquired via conventional tagging sequences. Cine DENSE yields 2D displacement-encoded images with a spatial resolution of 2.5 x 2.5 x 8 mm3 and temporal resolution of 30 milliseconds of a single slice (acquired over a 15- to 17-heartbeat breath-hold).26

Figure 15: Analysis of DENSE images provides strain maps in the radial and circumferential direction which can be gray scale or color coded. Also displacement vectors, illustrating the motion trajectory of the myocardium can be obtained.

Diffusion Tensor Imaging (DTI) CMR

Diffusion-encoding CMR techniques probe the diffusion properties of the myocardium thereby yielding maps of fractional anisotropy (FA), mean diffusivity (MD), or helix angles (HA) of the myocyte fibers.27 DTI of the heart is particularly demanding, because the diffusion coefficients to measure are orders of magnitude smaller than the bulk (contractile and respiratory-dependent) motion of the heart. Therefore, acceleration techniques and/or free-breathing strategies are applied for DTI. A diffusion-encoded stimulated echo (STEAM) pulse sequence incorporating parallel imaging, zonal (=spatially selected) excitation, and fast EPI read-outs was shown to yield reproducible results in healthy volunteers, when combined with breath-holds or navigator-gated free breathing modes.27 An example is given in Figure 16, below. This technique was then applied successfully in patients with HCMP and DCMP and yielded superb insights into myocardial microstructure during cardiac contraction in health and disease.28

Figure 16. Example b0 images (eight averages) and derived FA, MD, and HA maps for 2 contiguous slices in a normal volunteer. Note the similarity of BH and NAV acquisitions. The transmural evolution in HA can be robustly seen and can be reconstructed into 3D tractograms. With permission by John Wiley and Sons.

Research Applications

LV volumes and function

● Machine learning algorithms are currently under evaluation and show high potential to replace human observers for the calculation of LV and RV volumes and function29, 30

● Highly accelerated techniques can acquire full-coverage 3D data of the heart within a single breath-hold31

● Free-breathing 3D acquisitions can acquire full-coverage 3D data with high temporal and spatial isotropic resolution without the need for ECG-triggering32

● Such free-breathing approaches can be combined with velocity encoding for flow measurements in 3D33

● (Semi)-automatic localisation and acquisition procedures for operator-independent imaging34

Strain measurements

● Segmental LV strain measurements as well as RV and LA/RA strain measurements are not yet robust enough for clinical use and further refinements are needed

● The role of strain measurements to detect and monitor chemotherapy-induced cardiotoxicity is not yet well defined and clinical studies are warranted

Other deformation imaging techniques

● Most of the tagging, DENSE, velocity-encoding, and diffusion tensor imaging techniques discussed in this chapter are not yet part of routine CMR examinations. Research is ongoing particularly to standardize and facilitate the techniques with regards of acquisition and data analysis.21

● Diffusion tensor imaging (DTI-CMR) may yield novel insights into cardiac contractile mechanics.28 Additional evidence of its robustness is required before it is recommended to enter clinical routine.

● Tagging applications can help dyssynchrony assessment, e.g. before cardiac resynchronization therapy (CRT).22

References

1.      Zamorano JL, Lancellotti P, Rodriguez Muñoz D, et al. 2016 ESC Position Paper on cancer treatments and cardiovascular toxicity developed under the auspices of the ESC Committee for Practice Guidelines: The Task Force for cancer treatments and cardiovascular toxicity of the ESC. Eur Heart J. 2016;37:2768-2801.

2.      Armstrong GT, Plana JC, Zhang N, et al. Screening Adult Survivors of Childhood Cancer for Cardiomyopathy: Comparison of Echocardiography and Cardiac Magnetic Resonance Imaging. J Clin Oncol. 2012;30:2876-2884.

3.      Pedrizzetti G, Claus P, Kilner PJ, Nagel E. Principles of cardiovascular magnetic resonance feature tracking and echocardiographic speckle tracking for informed clinical use. J Cardiovasc Magn Reson. 2016;18:51.

4.      Puntmann VO, Valbuena S, Hinojar R, et al. Society for Cardiovascular Magnetic Resonance (SCMR) expert consensus for CMR imaging endpoints in clinical research: part I - analytical validation and clinical qualification. J Cardiovasc Magn Reson. 2018;20:67.

5.      Bruder O, Wagner A, Lombardi M, et al. European cardiovascular magnetic resonance (EuroCMR) registry – multi national results from 57 centers in 15 countries. J Cardiovasc Magn Reson. 2013;15:9.

6.      Danilouchkine M, Westenberg J, De Roos A, Reiber J, Lelieveldt B. Operator induced variability in cardiovascular MR: left ventricular measurements and their reproducibility. J Cardiovasc Magn Reson. 2005;7:447-457.

7.      Petersen SE, Aung N, Sanghvi MM, et al. Reference ranges for cardiac structure and function using cardiovascular magnetic resonance (CMR) in Caucasians from the UK Biobank population cohort. J Cardiovasc Magn Reson. 2017;19:18.

8.      Taylor RJ, Moody WE, Umar F, et al. Myocardial strain measurement with feature-tracking cardiovascular magnetic resonance: normal values. Eur Heart J-CVI. 2015;16:871-881.

9.      Peng J, Zhao X, Zhao L, et al. Normal Values of Myocardial Deformation Assessed by Cardiovascular Magnetic Resonance Feature Tracking in a Healthy Chinese Population: A Multicenter Study. Frontiers Physiol. 2018;9.

10.      Vo HQ, Marwick TH, Negishi K. MRI-Derived Myocardial Strain Measures in Normal Subjects. JACC: Cardiovascular Imaging. 2018;11:196-205.

11.      Claus P, Omar AMS, Pedrizzetti G, Sengupta PP, Nagel E. Tissue Tracking Technology for Assessing Cardiac Mechanics: Principles, Normal Values, and Clinical Applications. JACC: Cardiovascular Imaging. 2015;8:1444-1460.

12.      Augustine D, Lewandowski AJ, Lazdam M, et al. Global and regional left ventricular myocardial deformation measures by magnetic resonance feature tracking in healthy volunteers: comparison with tagging and relevance of gender. J Cardiovasc Magn Reson. 2013;15:8.

13.      Andre F, Steen H, Matheis P, et al. Age- and gender-related normal left ventricular deformation assessed by cardiovascular magnetic resonance feature tracking. J Cardiovasc Magn Reson. 2015;17:25.

14.      Eitel I, Stiermaier T, Lange T, et al. Cardiac Magnetic Resonance Myocardial Feature Tracking for Optimized Prediction of Cardiovascular Events Following Myocardial Infarction. JACC: Cardiovascular Imaging. 2018;11:1433-1444.

15.      Gavara J, Rodriguez-Palomares JF, Valente F, et al. Prognostic Value of Strain by Tissue Tracking Cardiac Magnetic Resonance After ST-Segment Elevation Myocardial Infarction. JACC: Cardiovascular Imaging. 2018;11:1448-1457.

16.      Buss SJ, Breuninger K, Lehrke S, et al. Assessment of myocardial deformation with cardiac magnetic resonance strain imaging improves risk stratification in patients with dilated cardiomyopathy. Eur Heart J - Cardiovasc Imaging. 2014;16:307-315.

17.      Bluemke D, Kronmal R, Lima J, Liu K, Olson J, Burke G, Folsom A. The Relationship of Left Ventricular Mass and Geometry to Incident Cardiovascular Events: The MESA (Multi-Ethnic Study of Atherosclerosis) Study. J Am Coll Cardiol. 2008;52:2148–55.

18.      Markman TM, Habibi M, Venkatesh BA, Zareian M, Wu C, Heckbert SR, Bluemke DA, Lima JAC. Association of left atrial structure and function and incident cardiovascular disease in patients with diabetes mellitus: results from multi-ethnic study of atherosclerosis (MESA). Eur Heart J - Cardiovascular Imaging. 2017;18:1138-1144.

19.      Vardoulis O, Monney P, Bermano A, Vaxman A, Gotsman C, Schwitter J, Stuber M, Stergiopulos N, Schwitter J. Single breath-hold 3D measurement of left atrial volume using compressed sensing CMR and a non-model-based reconstruction approach. J Cardiovasc Magn Reson. 2015;17:47.

20.      Kramer CM, Barkhausen J, Bucciarelli-Ducci C, Flamm SD, Kim RJ, Nagel E. Standardized cardiovascular magnetic resonance imaging (CMR) protocols: 2020 update. J Cardiovasc Magn Reson. 2020;22:17.

21.      Ibrahim E-S. Myocardial tagging by Cardiovascular Magnetic Resonance: evolution of techniques--pulse sequences, analysis algorithms, and applications. J Cardiovasc Magn Reson. 2011;13.

22.      Rutz AK, Manka R, Kozerke S, Roas S, Boesiger P, Schwitter J. Left ventricular dyssynchrony in patients with left bundle branch block and patients after myocardial infarction: integration of mechanics and viability by cardiac magnetic resonance. Eur Heart J. 2009;30:2117-2127.

23.      Castillo E, Osman N, Rosen B, El-Shehaby I, Pan L, Jerosch-Herold M, Lai S, Bluemke D, Lima J. Quantitative assessment of regional myocardial function with MR-tagging in a multi-center study: interobserver and intraobserver agreement of fast strain analysis with Harmonic Phase (HARP) MRI. J Cardiovasc Magn Reson. 2005;7:783-791.

24.      Ryf S, Tsao J, Schwitter J, Stuessi A, Boesiger P. Peak-combination HARP: A method to correct for phase errors in HARP. J Magn Reson Imaging. 2004;20:874-880.

25.      Schwitter J, Kanal E, Schmitt M, et al. Impact of the Advisa MRI™ Pacing System on the diagnostic quality of cardiac MR images and contraction patterns of cardiac muscle during scans: Advisa MRI randomized clinical multicenter study results. Heart Rhythm. 2013;10:864-72.

26.      Kuijer J, Hofman M, Zwanenburg J, Marcu sJ, van Rossum A, Heethaar R. DENSE and HARP: two views on the same technique of phase-based strain imaging. J Magn Reson Imaging. 2006;24:1432-1438.

27.      Nielles-Vallespin S, Mekkaoui C, Gatehouse P, et al. In vivo diffusion tensor MRI of the human heart: Reproducibility of breath-hold and navigator-based approaches. Magn Reson Med. 2013;70:454-465.

28.      Nielles-Vallespin S, Khalique Z, Ferreira PF, et al. Assessment of Myocardial Microstructural Dynamics by In Vivo Diffusion Tensor Cardiac Magnetic Resonance. J Amer Coll Cardiol. 2017;69:661-676.

29.      Bai W, Sinclair M, Tarroni G, et al. Automated cardiovascular magnetic resonance image analysis with fully convolutional networks. J Cardiovasc Magn Reson. 2018;20:65.

30.      Backhaus SJ, Staab W, Steinmetz M, Ritter CO, Lotz J, Hasenfuß G, Schuster A, Kowallick JT. Fully automated quantification of biventricular volumes and function in cardiovascular magnetic resonance: applicability to clinical routine settings. J Cardiovasc Magn Reson. 2019;21:24.

31.      Vincenti G, Monney P, Chaptinel J, et al. Compressed Sensing Single–Breath-Hold CMR for Fast Quantification of LV Function, Volumes, and Mass. JACC: Cardiovascular Imaging. 2014;7:882-892.

32.      Piccini D, Feng L, Bonanno G, et al. Four-dimensional respiratory motion-resolved whole heart coronary MR angiography. Magn Reson Med. 2017;77:1473-1484.

33.      Ma LE, Markl M, Chow K, et al. Aortic 4D flow MRI in 2 minutes using compressed sensing, respiratory controlled adaptive k-space reordering, and inline reconstruction. Magn Reson Med. 2019;81:3675-3690.

34.      Lelieveldt B, van der Geest R, Lamb H, Kayser H, Reiber J. Automated observer-independent acquisition of cardiac short-axis MR images: a pilot study. Radiology. 2001;221:537-542.

Chapter 2. Safety of MRI

R. Luechinger, PhD, Zurich, Switzerland

O. Bruder, MD, Essen, Germany

J. Schwitter, MD, Lausanne, Switzerland

Contraindications

● Absolute contraindications

. - Unknown active device, larger ferromagnetic implants, or unknown aneurysm clips

. - Metallic fragment in the eye or near sensitive tissue (larger nerves or blood vessels). In case of the eye perform orbita x-ray in unclear cases

. - Any implant known to be MR unsafe

● Relative contraindication

. - Scanning only possible after risk to benefit analysis and written informed consent recommended

. - Active devices which have not been tested to be MR conditional: some cardiac pacemakers (PM), implantable cardioverter-defibrillators (ICDs),1 insulin pumps, neurostimulators, back pain stimulators, and others

. - Removable devices (hearing aids, pumps, denture, etc. must be removed before entering the MR scanner room)

. - Long wires or bars (>10cm) risk of RF burns, especially if they will be located near or even inside the RF body coil

. - Claustrophobia

MR-conditional passive or active implants – online resources

. - Most of currently implanted stents, heart valves, sternum suture wires, cardiac closure and occluder devices, filters, embolization coils (at least at 1.5T)

. - Safe to scan, if labeling is taken into account

. - Current PMs and ICDs are likely to be MR-conditional1-4 (only a device together with the correct leads can be MR conditional, old leads may break label)

The information given in this chapter on safety is not exhaustive and for detailed information on specific devices or contrast media, the reader is directed to the manufacturer and/or guidelines and/or websites as listed below.

Online resources on implant safety:

Further information on safety of various implants can be obtained from:

. - http://www.mrisafety.com

. - http://magresource.com

Introduction - Potential safety risks from the electromagnetic fields

MRI is a widely accepted powerful diagnostic tool. In general, MRI is very safe and several 100 Mio. diagnostic studies have been performed safely up to now. However, there have been also over 16 published cases of patient deaths associated with MRI (ten with implanted PMs, two with an insulin pump, one with a neuro-stimulator, one with an aneurysm clip, and two persons killed by an oxygen tank). In addition hundreds of severe incidents mainly due to burns but also due to ferromagnetic projectiles are known. The loud noises (up to 120dB) induced by the fast switching gradient fields makes ear protections mandatory for all patient. Till 2010 500-600 cases of Nephrogenic Systemic Fibrosis (NFS) associated with linear Gadolinium-based CM have been reported world-wide (total Gd-doses sold approximately 200 Mio) that all occurred in patients with severe renal impairment. Incidence of this complication decreased dramatically since new recommendations were implemented. Recently minor Gd accumulations could be found in patients after multiple CM applications (see section on CM side effects). Most importantly, besides these known and preventable risks, no short or long-term side effects are known for MRI at the main magnetic field strengths currently used in clinical practice. In particular, it is reminded, that MRI like ultrasound, is not utilizing ionizing radiation, thus, preventing risk of inducing tumors.

Figure 1: The main magnetic field will attract any ferromagnetic device converting it into a dangerous projectile.

Due to the various potential risks in MRI patients must be very carefully screened for any contraindication. For example in 1992 a patient with a ferromagnetic aneurysm clip died during preparation for MRI, laying on the patient bed connected to the MR scanner. Due to a misunderstanding it was assumed that the clip is non-magnetic.5

Potential safety risks from the electromagnetic fields

Force and Torque effects

Three cases of fatal accidents associated with magnetic force and torque effects have been reported up to now. In 2001, a 6 year old boy was killed by a ferromagnetic oxygen tank. In 2018, a man died in India due to a ferromagnetic oxygen tank. Active shielded magnets (the commonly used magnets) have a fast increasing magnetic field limited to an area of a few meters around the magnet. Therefore, ferromagnetic materials can be brought rather near to the magnet without any noticeable force. However, moving it only by less than a meter, may induce forces which may no longer be controlled by humans. Ferromagnetic devices will speed up over a distance of 2-3 meters to over 50km/h! Therefore, it is of absolute importance that no ferromagnetic devices will be moved into the scanner room, preferable not even into the MR center. Monitoring devices, IV pols etc. which may enter the magnet room have to be tested and labeled as MR conditional.

Potential risks from the different electro-magnetic fields used in MRI. Table 1.

Table 1: Overview of potential risks from the different electro-magnetic fields and CM used in CMR. For all risks associated with active implants see list further down.

Risks from stress medication will be discussed in chapters 3 and 4.

Gradient noise

MR scanners may produce sound levels of over 115dB.6 Unprotected exposure to noise levels over 80dB can lead to temporary or even permanent raised hearing thresholds. Therefore, ear protections are mandatory for all MR measurements. Earplugs combined with headphones are preferable. If staff or other person has to stay in the scanner room during imaging, ear protection is also mandatory for them.

RF heating

The energy of the RF-field will partly be deposited in the tissues of the patients. The maximum allowed energy per volume (=specific absorption rate SAR) is carefully limited by international standards and are controlled by the MR scanners. In the normal operating mode whole body SAR is limited to 2W/kg and head SAR to 3.2W/kg. In the first level-controlled mode (whole body SAR<4W/kg), which will be indicated by the software of the MR scanner, additional monitoring of the patient may be needed. Patient may feel the heating effects, especially if the thorax is in the isocenter of the MR scanner. Pregnant women, small children, patient with impaired temperature regulation system, and others are only allowed to be scanned in normal operating mode.

Extended wires and implants may lead in addition to strong local tissue heating next to the implant. In 2003, a lumbar spine MRI scan at 1T resulted in a 2-3 cm large lesion at the tip of an intracerebral electrode of a neurostimulator, resulting in a severe permanent disability (MAUDE Database MDR Report Key: 474005). RF induced burns have also been reported due to wrongly connected or placed RF coils, conducting wire of monitoring cables7 etc. Even skin contact between both legs resulted in burns at the contact area. Longer implants and wires may concentrate the RF energy, which may lead to high heating in the tissue next to it. PM lead tips may heat up over 15°C in vivo.8

A Swiss news magazine reported: - Wearing the wrong clothes during an MRI investigation resulted in severe skin burns at both arms. The reason was 12% metal fibers in her blouse! - (Swiss News magazine: “Beobachter” Issue 5, 2010). Conductive metal fibers are also used in sport wares (silver fibers). Therefore, it is recommended to scan patients only when wearing clothes provided by the MR center or hospital.

Implants

Not only implants near the location intended to be imaged, but any active or passive implant in the patient has to be carefully checked whether it is safe for MRI or not.

For the definition of compatibility of an implant with respect to MR imaging, in 1997 the FDA developed the terms “MR safe” and “MR compatible”. In 2005 the American Society for Testing and Materials International (ASTM) developed a new set of terms: “MR safe”, “MR conditional”, and “MR unsafe”. The reader has to be aware that there might occur parallel utilization of the two different labeling of implants (FDA, ASTM), since no re-testing and re-labeling is foreseen for older products. The signs shown in Table 2 below may only be used for the new definition. The major different between the old and new definition of “MR safe” is, that with the new definition an implant which is “MR safe” has to be safe under any, even future MR conditions. “MR conditional” means safe under certain conditions (e.g. field strength, specific absorption rate (SAR), patient positioning, scan duration, and others), which have to be specified in detail for any given device.

Table 2: Terminology used for labelling of Implants (ASTM F2503-13)

Passive implants may interact mainly with the main magnetic field (force and torque effects) and RF field which may induce heating. Most of currently implanted stents, heart valves, sternum suture wires, cardiac closure and occluder devices, filters, embolization coils, and screws are MR-conditional at least up to 1.5T.9, 10 Some of them may request a limitation of whole body SAR to 2W/kg or even lower. A few implants request a 6 week waiting period before an MRI is allowed. This may be the case for implants, which show higher force and torque effects to allow the implant to be fixated by scare tissue before entering MRI or in case of active implants like pacemakers the healing at the lead tip tissue interface will still alter some of the pacing parameters. To avoid misinterpretation of changes in the pacing parameter after an MRI most manufacturer asked for a 6 week waiting period after lead implantation.

However, general advices on safety of an implant can be dangerous. For example, most of the aneurysm clips are non-magnetic, however, a aneurysm clip implanted 1968 and imaged 1992 was MR-unsafe and resulted in a fatal outcome.5

Active implants may react on the different RF-fields of an MR unit and safety evaluations are much more complicated. Due to the steadily increasing number of implants, it is not possible to give general advices on safe or unsafe implants. For specific implants it is recommended to refer to the manufacturer’s product information, dedicated web sites on MRI safety https://www.mrisafety.com/

https://magresource.com/

https://www.acr.org/%20Clinical-Resources/Radiology-Safety/MR-Safety

or reference manuals (e.g. Reference Manual for Magnetic Resonance Safety, Implants, and Devices from Frank Shellock).11 The American Heart Association published in Circulation an overview on safety of cardiovascular devices.9

Some adjustable shunts in the brain and other adjustable devices have been labeled as MRI conditional and may therefore be imaged in MRI, but they need to be readjusted after MRI. On the other side, there exist several devices, which need special care or represent even an absolute contraindication. Special attention is needed for any kind of active devices like PMs, ICDs, neuro-stimulator, and insulin and other drug pumps. Certain drug and insulin pumps are safe to undergo MRI under specific conditions (for some the reservoir needs to be empty to avoid depletion during the MRI investigation).

All major PM and ICD manufacturer have different MR conditional systems on the market. In several countries the larger portion of implanted MR systems are now MR conditional. But due to old leads, abandoned leads, leads from different manufacturer, higher prices, etc. an implantation of an MR conditional system is not always possible.

A consensus paper of the German Roentgen Society and the German Cardiac Society gives a detailed overview over physical and electrophysiological background information and specific recommendations for the procedural management of patients with cardiac pacemakers (PM) and implantable cardioverter defibrillators (ICD) with and without MR conditional pacing systems.1, 4

Potential risks of PMs and ICDs in the MR environment

● Static magnetic field

. - Mechanical forces on ferromagnetic components

. - Unpredictable magnetic sensor activation, reed-switch closure

. - Changes in electrocardiograms

● Modulated radio frequency (RF) field

. - Heating of cardiac tissue adjacent to lead electrodes

. - Possible induction of life-threatening arrhythmias (very rare)

. - PM reprogramming or reset

. - RF interactions with the device (over- and under-sensing)

● Gradient magnetic field

. - Possible induction of life-threatening arrhythmias (unlikely in

. - bipolar mode)

. - Induced voltages on leads cause over- and under-sensing

. - Case heating

● Combined field effects

. - Alteration of device function due to electromagnetic interference

. - Mechanical forces (vibration)

. - Electronic reset of device

. - Damage to PM/ICD and/or leads

. - PMs are switched either to asynchronous magnet or interference mode

. - ICD therapy is switched off and interference mode does not exist

With non-MR conditional PMs and ICDs, there is a known risk for high heating effects8 and a risk for inappropriate inhibition and/or stimulation.12 As MR examinations in these patients are contraindicated by FDA and EMEA, it is not recommended to perform MR examinations in these patients, unless the examination is of vital importance for the patient and the potential benefit of the examination clearly outweighs the possible risks. In this situation a written informed consent from the patient is recommended.1, 4, 13

Some of the currently available pacing systems are approved for 1.5T and 3T, others only for 1.5T. Most of them can be scanned without any anatomical restriction, others have an exclusion zone (different size for different vendors and some vendors have even different zone for different products). Most of the pacing system do not request any reduction of the gradient performance on current MR systems. The RF power needs normally to be limited to normal operating mode (2W/kg whole body SAR) a few are also approved for 4W/kg. In any case patient monitoring (PPU is preferred) is requested and the pacing systems need to be reprogrammed before MRI and after MRI. Some devices include an auto MRI mode, which detects the strong magnetic field of an MRI system and switch automatically when entering an MRI scanner. However, also those modes need to be activated before MRI, but the patient still gets the default pacing outside MRI. This auto MRI mode is only active for a limited time (a few days).

Very important: Please read the instruction for use of the implanted system to follow all restriction for MRI. Some device have an exclusion for patient with fever, other request a minimal patient size, no other implants near the pacing lead, only patient position supine etc.

Cases

Example of a CMR examination in a patient with an MR-conditional PM

In 2008 the first MR conditional designed pacing system was introduced to the market.2 Such a device was implanted in a patient with a systemic sclerosis with involvement of the skin (positive biopsy), lungs (interstitial pneumopathy), vessels (Raynaud syndrome, stent implantation into the left subclavian artery, history of peripheral sympathectomy), muscles (with constantly elevated CK), esophagus, and the heart. Cardiac involvement consists of fibrotic tissue in the interventricular septum (Figure 2) which resulted in a complete AV-block, for which the patient was then implanted with an MR-conditional PM. CMR demonstrated a reduced systolic LV function (with an EF of 32% measured during pacing at 100 bpm). The patient is under immuno-suppressive therapy.

Figure 2: Short-axis views of the heart in end-diastole (left) and end-systole (right). Small structures such as ventricular trabecula are well visualized. A small artefact of the PM lead is visible in inferior part of the RV (arrow). The labeling of the pacing system requested a whole body SAR limit of 2W/kg which had no impact on the image quality. Bottom: LGE also yields good quality images in this patient with several small scar areas in the interventricular septum (arrow heads) and fibrosis at the posterior insertion point of the RV into the interventricular septum. Mild aortic insufficiency causes a signal void in this 3-chamber LGE image acquired in mid-diastole.

In this multi-organ disease, it is important to be able to monitor disease activity of all organ systems by MR imaging.

Protocol for MR-conditional PMs or ICDs

!! Check device for MR-conditional use (PM/ICD AND leads)

!! In patients with implanted devices, chest X-ray should be taken prior to CMR imaging if any abandoned/looped/ dysfunctional or fractured leads are suspected.

!! Check conditions for MR imaging (specific for each device, may differ between vendors)

. - field strength

. - exclusion zones (often thorax in which case CMR would not be possible)

. - time interval after device/lead implantation (often >6 weeks)

. - maximum whole body SAR (often 2W/kg, sometimes 4W/kg)

. - others

● Program device to MR-mode (print out new settings for documentation). Some patients may need monitoring starting with the reprogramming until after the MRI when the original settings have been restored (see position paper1)

● Perform MR scan

.