Quantification of the area-at-risk by T1 and T2 mapping CMR at 3T

Abstract

Background Measuring the area-at-risk (AAR) allows the assessment of myocardial salvage in reperfused STEMI patients. T2weighted CMR has been used to quantify the AAR but is hampered by low signal-to-noise ratio and image artifacts. T1 and T2 mapping CMR may improve upon this. We compared T1 and T2 mapping for quantifying the AAR at 3T. Methods CMR imaging at 3T (Bio-graph mMR, Siemens Healthcare, Erlangen, Germany) was performed in 18 STEMI patients within 10 days of PPCI using T2-mapping and T1-mapping by MOLLI (WIP #699; Siemens Healthcare; UK). Matched short-axis T1 and T2 maps covering the entire left ventricle were analyzed by 2 experienced investigators using 3 analytical methods (in-house macro, ImageJ): manual segmentation, Otsu, and the 2 standard deviation (2SD) thresholding (Fig. 1). Regions-of-interest were drawn in the AAR and remote myocardium. Two investigators analyzed the coronary angiograms to obtain the BARI and APPROACH angiography scores to provide a CMR-independent estimate of the AAR. Results T1 and T2 values were increased within the AAR compared with remote myocardium (mean±SD: T1, 1525 ±116ms vs. 1163±78ms, P<0.001 and T2, 72±7ms vs. 46