Disclosures. GETTING TO THE HEART OF THE MATTER WITH MULTIMODALITY CARDIAC IMAGING Organ Review Meeting 25 September. Overview

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1 GETTING TO THE HEART OF THE MATTER WITH MULTIMODALITY CARDIAC IMAGING Organ Review Meeting 25 September Disclosures None relevant to this presentation Mini Pakkal Assistant Professor of Radiology University Hospital Network Toronto Overview Overview of the relevant concepts of various cardiac imaging modalities Spatial Time of acquisition Anatomical vs functional imaging Exploit the strengths of the various cardiac modalities to answer specific clinical questions Select examples Imaging modalities 1

2 Coronary CT angiogram Coronary MR angiogram MRCA vs. MDCT Meta-analysis Search until June MDCT studies (7516 patients) 20 MRCA studies (989 patients) 1 study at 3T 5 head to head comparisons (325 patients) QCA 50% diameter stenoses Sensitivity Specificity AUC MDCT 97% (96-98%) 87% (84-90%) 98% (96-99%) MRCA 87% (83-90%) 70% (60-79%) 89% (86-91%) Schuetz et al. Ann Intern Med 2010 Proximal stenoses 1.5T Non- targeted SSFP 64 Slice MDCT MRA CT MRA + 30 patients CT Sensitivit 85% 83% 92% y Specificit 87% 87% 92% y NPV 60% 59% 72% PPV 96% 97% 98% Accuracy 87% 86% 94% Cheng et al. IJC 2013 Anomalous coronary artery origins Calcified Plaques 27 patients with at least 1 calcified plaque with a calcium score >100 (33 plaques) 1.5T vs. 64 Slice (Targeted 3D and Whole Heart with a 8 or 6 element coil) MRI MDCT P Sensitivity Specificity ROC Area ACCF/ACR/AHA/NASCI/SCMR Expert Consensus document Circ 2010 Liu et al. AJR

3 - Summary MR vs CT Spatial of MR is 1-2 mm, CT is mm CT better than MR for coronary artery stenosis >=50 % 30 %-50 % of segments cannot be evaluated Takes longer (mins vs msec) Best for proximal and mid segments No radiation exposure No No blooming artefact from calcium CT coronary artery atherosclerosis MR anomalous origins, aneurysms Spatial of MR vs Nuclear (SPECT) MR Impact II trial 33 centres, 465 patients Stenosis >50% AUC CMR =0.75 AUC Spect =0.65 CMR consistently detected more subendocardial perfusion defects and infarcts than SPECT Time to acquire data for image shutter speed Moving object requires fast shutter speed and short time window to acquire the image The heart is a moving target Mean Translational Motion LAD 22.4 mm/s ± 4 RCA 69.5 mm/s ± 22 CX 48.4 mm/s ± 15 Normal coronary artery between 2-5mm Achenbach, Radiology 2000 Courtesy: Sue Edyvean 3

4 Conventional angio is superior to cardiac CT (better spatial and temporal ) Modern CT scanners handle higher heart rates well and MR are superior to CT for assessment of moving structures such as valves better than MR for assessment of valvular and subvalvular structures e.g. mitral valve Mitral valve Functional vs anatomical imaging in CAD Anatomical description of stenosis <50% stenosis = mild 50-69% stenosis = moderate >=70% stenosis = severe What does it mean? Gould and Lipscomb, 1974 found that stenosis of <50% less likely to be functionally significant Basic principle of investigation of choice ANATOMICAL AND FUNCTIONAL IMAGING Fame substudy 2010 Stenosis severity %Functionally significant %Functionally non significant 50-70% 35% 65% 71-90% 80% 20% 91-99% 96% 4% A 50-70% stenosis can be signficant Length and number of stenosis Proximal stenosis subtend a larger area Increased oxygen consumption e.g. left ventricular hypertrophy Decreased arterial oxygen saturation e.g anaemia Case 1 55 yr F Atypical Chest pain 4

5 Case 2 Case 2 47 yr M, Asian Atypical Chest pain Smoker CACS=26 Next step: CCTA Case 3 Case 3 45 yr M Atypical Chest pain No risk factors CAC = 151 Spatial of MR vs Nuclear (SPECT) MR Impact II trial 33 centres, 465 patients Stenosis >50% AUC CMR =0.75 AUC Spect =0.65 CMR consistently detected more subendocardial perfusion defects and infarcts than SPECT Attenuation Artefact Heart surrounded by varying amounts of attenuation material tissue bone and lung. Attenuation different between males and females Male Diaphragm attenuation Female Breast attenuation LV LV Causes inferior wall artefact Causes anterior wall artefact 5

6 Gut activity adjacent to the inferior wall Perfusion defects MR vs SPECT Radiation issues - 8mSv (4mSv for stress and rest each) Large patients Left main stem and three vessel disease false negative with SPECT scans LBBB Throughput through the MR scanner/reporting time Renal dysfunction Triaging mechanism - What about stress echocardiography Based on demonstrating contractile reserve rather than vasodilatory reserve Is more specific as systolic dysfunction occurs much later in the ischaemic cascade Low sensitivity (26%) in severe left ventricular dysfunction due to impairment of ionotropic reserve 6

7 Viable Myocardium Acute MI Scar Transmurality of infarct Intact cell membranes [] = Low Ruptured cell membranes [] = High Collagen matrix [] = High im RJ, Choi M, Judd RM. In Cardiovascular MRI and MRA, Higgins and DeRoos editors im viability 0%: 78% of segments with no DE showed good functional recovery. 1-25%: 60% of segments showed functional recovery 26-50%: 42% of segments showed functional recovery 51-75%: 10% of segments showed functional recovery >75%: 2% of segments recovered Subendocardial infarct Infarction delayed enhancement Case 1 35 year old with chest pain Raised troponins Normal coronary angiogram 7

8 Myocarditis Case 2 28 year old Presented with multiple episodes of syncope and palpitations 2:1 heart block on ECG Sarcoidosis Case 3 65 year old Hypertension Presented with CCF slow response showed concentric hypertrophy 8

9 ECG Amyloidosis Summary What is the functional significance of the anatomical abnormality I am seeing? with delayed enhancement subendocardial vs non subendocardial Acknowledgment Course organisers Ben Ariff and Su Edyvean The cardiothoracic imaging divisions in JDMI and Toronto 9