Measurement of Myocardium at Risk with Cardiovascular MR: Comparison of Techniques for Edema Imaging

Purpose To determine variability and agreement for detecting myocardial edema with T2-weighted short-tau inversion recovery ( STIR short-tau inversion recovery ), acquisition for cardiac unified T2 edema ( ACUT2E acquisition for cardiac unified T2 edema ), T2 mapping, and early gadolinium enhancement ( EGE early gadolinium enhancement ) after successfully reperfused ST-segment-elevation myocardial infarction ( STEMI ST-segment-elevation myocardial infarction ) and diagnostic accuracy of each sequence to predict infarct-related artery ( IRA infarct-related artery ). Materials and Methods Local ethics committee approved the study, with patient informed written consent. On day 2 after successful primary angioplasty for STEMI ST-segment-elevation myocardial infarction , 53 patients were prospectively enrolled; 40 patients (mean age, 60 years) completed study. Two sets of cardiac magnetic resonance (MR) images were obtained on same day 6 hours apart. Basal, midcavity, and apical sections were obtained with each sequence. Interobserver, intraobserver, and interimage variability (1 minus intraclass correlation coefficient) and agreement (Bland-Altman method) were assessed. Results Size of myocardial edema significantly differed. Mean size of myocardium at risk was similar between T2-weighted STIR short-tau inversion recovery (18.2 g) and T2 mapping (17.3 g) (P = .54). Mean size differed between T2-weighted STIR short-tau inversion recovery (18.2 g) and ACUT2E acquisition for cardiac unified T2 edema (14.0 g) (P = .01) and between T2-weighted STIR short-tau inversion recovery (18.2 g) and EGE early gadolinium enhancement (14.2 g) (P = .003). T2 mapping and EGE early gadolinium enhancement had best agreement (interobserver bias: T2-weighted STIR short-tau inversion recovery , -0.9 [mean difference] ± 9.6 [standard deviation]; ACUT2E acquisition for cardiac unified T2 edema , -2.5 ± 6.9; T2 mapping, -3.8 ± 4.7; EGE early gadolinium enhancement , -5.3 ± 5.9; interimage bias: T2-weighted STIR short-tau inversion recovery , 1.5 ± 5.8; ACUT2E acquisition for cardiac unified T2 edema , -0.8 ± 4.9; T2 mapping, 3.1 ± 4.0; EGE early gadolinium enhancement , 1.1 ± 4.9; intraobserver bias: T2-weighted STIR short-tau inversion recovery , 1.4 ± 5.8; ACUT2E acquisition for cardiac unified T2 edema , 0.6 ± 4.7; T2 mapping, 2.2 ± 3.1; EGE early gadolinium enhancement , 1.7 ± 2.9). Variability was lowest for T2 mapping (intraobserver, 0.05; interobserver, 0.09; interimage, 0.1) followed by EGE early gadolinium enhancement (intraobserver, 0.03; interobserver, 0.14; interimage, 0.14), with improved detection of territory of IRA infarct-related artery versus ACUT2E acquisition for cardiac unified T2 edema (intraobserver, 0.11; interobserver, 0.22; interimage, 0.12) and T2-weighted STIR short-tau inversion recovery (intraobserver, 0.1; interobserver, 0.32; interimage, 0.1). Conclusion Cardiac MR methods to detect and quantify infarct myocardial edema are not interchangeable; T2 mapping is the most reproducible method, followed by EGE early gadolinium enhancement , ACUT2E acquisition for cardiac unified T2 edema , and T2-weighted STIR short-tau inversion recovery . Clinical trial registration no. NCT01468662 © RSNA, 2014 Online supplemental material is available for this article.