Cardiovascular sciences Outils d évaluation myocardique par relaxométrie (Myomaps) Alain Nchimi
Geva T. Magnetic resonance imaging: historical perspective. J Cardiovasc Magn Reson. 2006;8(4):573-80.
CMR historical perspective Geva T. Magnetic resonance imaging: historical perspective. J Cardiovasc Magn Reson. 2006;8(4):573-80.
Some of the then needs Faster easier to compute imaging Characterize the myocardial tissue Edema/Inflammation Fat Iron Scar (stunning) No-reflow/MVO Quantifiable Sizeable benefits Hard/softwares Parallel imaging
normal myocardium acute MI scar K K K K K K K K K K Myocardial ECV imaging Delayed enhancement viability : Higher [] = shorter T1 Intact cell membranes Ruptured cell membranes Collagen matrix [] = Low [] = High [] = High Kim RJ, Choi KM, Judd RM. In Cardiovascular MRI and MRA, Higgins and DeRoos editors
Infarct Myocardial ECV imaging Myo-pericarditis sarcoidosis Nchimi A et al. Expert Rev Cardiovasc Ther. 2015 May;13(5):565-76. HCM DCM
Myocardial ECV fibrosis Focal Perimysial Perivascular Plexiform Sibley et al. Radiology: 2012 ;265(3):724-732 Patchy Diffuse
Voxel-based MRI signals
MyoMaps quantifies tissue characteristics e.g. amylosis with MyoMaps; T1 Map (ms) T1>1200ms tional Institute of Health, Bethesda, U.S. Restricted Siemens AG 2014 All rights reserved. Page 9 e.g. myocardial edema with MyoMaps; T2 Map (ms) Acute myocardial injuries diagnostikum berlin, Berlin, Germany iron overload with MyoMaps; T2* Map (ms) T2 < 10 ms predict heart failure Dudley Pennell, Royal Brompton Hospital, London, UK Magnetic Resonance
T2 & T2* Map@MyoMaps - Technical Details T2-prepared single shot truefisp or GRE images Motion correction Robust 2 parameter pixel-wise fitting Inline T2 map generation Developed in collaboration with: Dr. Simonetti, The Ohio State University, Columbus, OH 1 Giri et al. JCMR 2009 Multi-echo segmented GRE Robust pixel-wise fitting 1 180 T2Star-Linear-LSE-Cost=123.3013-T2Star=41.4238 T2Star-NonLinear-LSE-Cost=123.3013-T2Star=41.4238 160 T2Star-NonLinear-LAD-Cost=123.0776-T2Star=40.9759 T2Star-Linear-LSE-robust-Cost=123.3013-T2Star=41.4238 T2Star-NonLinear-LSE-robust-Cost=123.3013-T2Star=41.4238 140 T2Star-NonLinear-LAD-robust-Cost=122.8753-T2Star=41.0475 Inline T2* map generation 120 100 80 60 40 20 0 0 10 20 30 40 50 60 70 80 90 100 Restricted Siemens AG 2014 All rights reserved. Page 10 1 Shah et al. Proc. Of SCMR / EuroCMR Joint Scientific Sessions, 2011 Magnetic Resonance
Myocardial ECV imaging Look DC, Locker DR. Time saving in measurement of NMR and EPR relaxation times. Rev Sci Instrum 1970. ECG sync Dynamic motion correction Significant differences @ shorter T1 values (overestimation by LL) cif MS et al. Myocardial T1 mapping with MRI: comparison of look-locker and MOLLI sequences. J Magn Reson Imaging. 2011 34:1367-73. Messroghli DR et al. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med 2004.
Myocardial ECV imaging Increasing inversion time Signal intensity Iles et al. J Am Coll Cardiol 2008
Myocardial ECV imaging Confounders Field strength Temperature Heart rate Hematocrit (gender) Age Regional variations Diseases (unenhanced) Amyloid (T1 > 1200ms @ 1.5T) Fabry White et al. Heart 2012;98:773-779; Kawel et al. J Cardiovasc Magn Reson. 2012 May 1;14:27.
Myocardial ECV imaging Dass et al. Circ Cardiovasc Imaging. 2012 Messroghli et al. Magn Reson Med 2007 Piechnik et al. J Cardiovasc Magn Reson 2010 Iles et al. J Am Coll Cardiol 2008 Jelis et al. Circ Cardiovasc Imaging 2011 Suehoshi et al. et al. Am J Roentgenol 2010 [] Pseudo-equilibrium (15-30 ) T1 value T1 (-blood) Subtract partition coefficient Arheden et al. Radiology 1999 Flacke et al. Radiology 2001 Normalize with the haematocrit Volume of distribution Arheden et al. Radiology 1999 Klein et al. J Magn Reson Imaging 2004 Schelbert el al. J Cardiovasc Magn Reson 2011 Ugander et al. Eur Heart J 2012 Modelization of the distribution volume Jerosh-Herold et al. Am J Physiol Heart Circ Physiol 2008 T1 value T1 (-blood) Volume of distribution via equilibrium (dedicated injection protocols) Flett et al. Circulation 2010
Correlation with histology Flett A et al. Equilibrium contrast cardiovascular magnetic resonance for the measurement of diffuse myocardial fibrosis: preliminary validation in humans.circulation 2010
ECV does not relates to EF Ng et al. Association between diffuse myocardial fibrosis by cardiac magnetic resonance contrast-enhanced T₁ mapping and subclinical myocardial dysfunction in diabetic patients: a pilot study. Circ Cardiovasc Imaging 2012
ECV clinical summary Myocardial enhancement fraction is higher in diseased (hypertrophic and dilated cardiomyopathies) than in normal (late 2000 s) Correlation with arrhythmias (early 2010 s) Correlation with other heart failure biomarkers (late 2010 s) BNP Echo strain Prognostic value post repair in afterload states (hypertension, aortic valve stenosis)
Journal publications on T1 mapping / ECV T1 mapping @ the 2014 SCMR SCMR abstracts 2010: 5 abstracts 1% 2011: 23 abstracts 5% 2012: 36 abstracts 8% 2013: 46 abstracts 9% 2014: 63 abstracts 15% 70 60 50 40 30 20 10 0 1997 1999 2001 2003 2005 2007 2009 2011 2013 Restricted Siemens AG 2014 All rights reserved. Page 18 Slide courtesy or Dr. James Moon, The Heart Hospital, London Magnetic Resonance
CMR relaxometries Clinical indications Cardiomyopathies Remodeling Valvular diseases Infarct Overload Arrhythmias Expectations Multiparametric 3D relaxometries Texture analysis Intravoxel signal interpretation
Summary Robust, reproducible and easy myocardial relaxometry (MyoMaps) is significant part of an ongoing technical progress stream Relaxometry is establishing itself as a standard in characterizing the myocardial tissue Its use as marker of disease outcome is currently under investigation in a large number of clinical scenario