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

BackgroundBoth 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. PurposeTo investigate the reliability of AMI and CMI characterization using native T-1 mapping and its feasibility for discriminating AMI from CMI. Study TypeCase-control. Animal ModelThe study cohort comprised 12 AMI (mean post-MI, 3.751.29 days) and 15 CMI (mean post-MI, 39.536.10 days) Bama mini-pigs. Field Strength/SequenceBalanced steady-state free precession (bSSFP), segmented-turbo-FLASH-PSIR, and modified Look-Locker inversion recovery (MOLLI) sequences at 3.0T. AssessmentThe infarct sizes were compared on matching short-axis slices of late-gadolinium-enhanced (LGE) images and T-1 maps by two experienced radiologists. Statistical TestsThe infarct sizes were compared on matching short-axis slices of LGE images and T-1 maps, and agreement was determined using linear regression and Bland-Altman analyses. The native T-1 values were compared between AMI and CMI models (independent sample t-test). The intraclass correlation coefficient was used to assess inter- and intraobserver variability. ResultsMeasured infarct sizes did not differ between native T-1 mapping and LGE images (AMI: P=0.913; CMI: P=0.233), and good agreement was observed between the two techniques (AMI: bias, -3.3819.38%; R-2=0.96; CMI: bias, -10.5510.90%; R-2=0.90). However, the native infarction myocardium T-1 values and the T-1 signal intensity ratio of infarct and remote myocardium (T-1 SI ratio) did not differ significantly between AMI and CMI (P=0.173). Data ConclusionNoncontrast native T-1 mapping can accurately determine acute and chronic infarct areas as well as conventional LGE imaging; however, it cannot distinguish acute from chronic MI. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1406-1414.