Layer-specific strain-encoded MRI for the evaluation of left ventricular function and infarct transmurality in patients with chronic coronary artery disease

BACKGROUND:The study aimed to evaluate whether layer-specific myocardial deformation imaging performed by strain-encoded imaging (SENC) allows quantification of regional left ventricular function and is related to scar transmurality defined by contrast-enhanced magnetic resonance imaging (ceMRI) in patients with chronic coronary artery disease (CAD). METHODS:50 patients (mean age 62 ± 10 years) with CAD underwent ceMRI. Regional myocardial function was evaluated semi-quantitatively from steady-state free-precession cine sequences. Layer-specific peak circumferential strain was measured from long-axis views and peak longitudinal strain was evaluated from short-axis views in a 16-segment model. The extent of myocardial infarction was determined semiautomatically for each segment as relative amount of hyperenhancement by ceMRI. Wall motion and the degree of hyperenhancement were related to layer-specific myocardial strain. RESULTS:A total of 589 of 600 segments (98%) were analysed. Endocardial and epicardial circumferential as well as longitudinal strain showed significant differences between visually defined segmental function states and differed also significantly between the degree of infarct transmurality (all p<0.001). A cutoff peak circumferential endocardial strain value of -15% differentiated nontransmural from transmural infarcted myocardium with a sensitivity of 100% and a specificity of 86% (area under the curve (AUC) 0.94). Distinction of nontransmural infarcted myocardium from transmural infarcted myocardium was done more accurately using circumferential endocardial strain compared to longitudinal endocardial strain (AUC 0.94 vs. AUC 0.76, p=0.003). CONCLUSIONS:Quantitative analysis of segmental deformation by layer-specific SENC allows accurate discrimination between different transmurality states of myocardial infarction in patients with chronic CAD. Circumferential endocardial strain showed the best distinction between the different degrees of infarct transmurality.