Strain-encoded MRI for evaluation of left ventricular function and transmurality in acute myocardial infarction.

BACKGROUND

Strain-encoded imaging (SENC) is a new technique for myocardial deformation analysis in cardiac MRI. The aim of the study was, therefore, to evaluate whether myocardial deformation imaging performed by SENC allows for quantification of regional left ventricular function and is related to transmurality states of infarcted tissue in patients with acute myocardial infarction.

METHODS AND RESULTS

Cardiac MRI was performed in 38 patients with acute myocardial infarction 3+/-1 days after successful reperfusion using a clinical 1.5-T MRI scanner. Ten healthy volunteers served as controls. SENC is a technique that directly measures peak circumferential strain from long-axis views and peak longitudinal strain from short-axis views. Measurements were obtained for each segment in a modified 17-segment model. Wall motion and infarcted tissue were evaluated semiquantitatively from steady-state free-precession cine sequences and contrast-enhanced MR images and were then related to myocardial strain. Comparison of peak circumferential strain assessed by SENC and MR tagging was performed. In total, 456 segments were analyzed. Peak circumferential and longitudinal strain calculated from SENC images was significantly different in regions defined as normokinetic, hypokinetic, or akinetic (P<0.001). A cutoff peak systolic circumferential strain value of -10% differentiated nontransmural from transmural infarcted myocardium, with a sensitivity of 97% and a specificity of 94%. Strain analysis of SENC and MR tagging correlated well (r=0.76) with narrow limits of agreement (-9.9% to 8.5%).

CONCLUSIONS

SENC provides rapid and objective quantification of regional myocardial function and allows discrimination between different transmurality states in patients with acute myocardial infarction.