Characterizing Myocardial Edema and Hemorrhage Using Quantitative T2 and T2* Mapping at Multiple Time Intervals Post ST-Segment Elevation Myocardial Infarction

Abstract

Background— Accurate characterization of the longitudinal trends of myocardial edema and hemorrhage has been previously limited by subjective qualitative methods. We aimed to prospectively characterize the evolution of myocardial edema and hemorrhage post acute myocardial infarction using quantitative measures. Methods and Results— Sixty-two patients were enrolled post primary percutaneous coronary intervention and underwent cardiovascular magnetic resonance on a 1.5-T scanner at 48 hours, 3 weeks, and 6 months. Myocardial edema and hemorrhage were assessed by T2 and T2* mapping, respectively, in both infarct segment (IS) and remote segment (RS). At 48 hours, T2 is higher in IS compared with RS (56.7 ms versus 43.4 ms; P <0.01). At 3 weeks T2 remains higher in IS compared with RS (51.8 ms versus 39.5 ms; P <0.01), and subsequently equalizes by 6 months (39.8 ms versus 39.5 ms; P =nonsignificant). T2 is also increased in RS at day 2 versus 3 weeks (43.4 ms versus 39.5 ms; P <0.01). At 48 hours T2* was reduced in IS compared with RS (32.4 ms versus 37.4 ms; P <0.01). At 3 weeks (IS, 37.7 ms versus RS, 38.4 ms; P =nonsignificant) and 6 months (IS, 37.3 ms versus RS, 38.2 ms; P =nonsignificant), T2* values were equal in both segments. Conclusions— Quantification of myocardial edema and hemorrhage by T2 and T2* mapping is feasible post acute myocardial infarction and demonstrates that hemorrhage resolves faster than edema. Noninfarcted segments can also demonstrate edema in the acute phase possibly due to global hyperemia.