Native T1 mapping for characterization of acute and chronic myocardial infarction in swine: Comparison with contrast-enhanced MRI.

Abstract

Both acute and chronic myocardial infarction (AMI and CMI, respectively) exhibit delayed enhancement; however, clinical decision-making processes frequently require the differentiation of these two types of myocardial injury. To investigate the reliability of AMI and CMI characterization using native T1 mapping and its feasibility for discriminating AMI from CMI. Case-control. The study cohort comprised 12 AMI (mean post-MI, 3.75 ± 1.29 days) and 15 CMI (mean post-MI, 39.53 ± 6.10 days) Bama mini-pigs. Balanced steady-state free precession (bSSFP), segmented-turbo-FLASH-PSIR, and modified Look-Locker inversion recovery (MOLLI) sequences at 3.0T. The infarct sizes were compared on matching short-axis slices of late-gadolinium-enhanced (LGE) images and T1 maps by two experienced radiologists. The infarct sizes were compared on matching short-axis slices of LGE images and T1 maps, and agreement was determined using linear regression and Bland-Altman analyses. The native T1 values were compared between AMI and CMI models (independent sample t-test). The intraclass correlation coefficient was used to assess inter- and intraobserver variability. Measured infarct sizes did not differ between native T1 mapping and LGE images (AMI: P = 0.913; CMI: P = 0.233), and good agreement was observed between the two techniques (AMI: bias, -3.38 ± 19.38%; R2 = 0.96; CMI: bias, -10.55 ± 10.90%; R2 = 0.90). However, the native infarction myocardium T1 values and the T1 signal intensity ratio of infarct and remote myocardium (T1 SI ratio) did not differ significantly between AMI and CMI (P = 0.173). Noncontrast native T1 mapping can accurately determine acute and chronic infarct areas as well as conventional LGE imaging; however, it cannot distinguish acute from chronic MI. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1406-1414.