190 Quantification of myocardial infarction by cardiovascular magnetic resonance late gadolinium enhancement imaging: comparison of magnitude-based versus phase-sensitive inversion recovery

Introduction Late gadolinium enhancement (LGE) imaging with cardiovascular magnetic resonance (CMR) is considered the non-invasive gold standard for identifying and quantifying myocardial scar. The diagnostic and prognostic importance of myocardial scar quantification by CMR has been demonstrated in a variety of cardiac pathologies. With CMR imaging, phase-sensitive inversion recovery (PSIR) techniques have been integrated alongside traditional magnitude-based LGE (MAG) protocols in order to provide resilience to inversion time (TI) variations. PSIR techniques effectively mitigate against the challenges of inadequate myocardial signal nulling. Traditionally, MAG and PSIR techniques have been used interchangeably in clinical settings. However, the comparative accuracy in myocardial scar quantification of these techniques remains uncertain. The aim of this study was to compare scar quantification using both methods in a population with ischaemic heart disease. Methods In a prospective study involving post-reperfusion ST elevation myocardial infarction (STEMI) patients, CMR was performed at acute (4–5 days post-MI) and chronic (4 months post-MI) phases. For scar quantification, MAG and PSIR images acquired at each timepoint were analysed with the Full Width at Half Maximum (FWHM) method using commercially available software. To ensure consistency, identical contours were applied to both PSIR and MAG LGE images. Exclusion zones were delineated to exclude non-infarct territories and minimize erroneous signal detection. To compare scar quantification between MAG and PSIR techniques, Bland-Altman plots and intraclass correlation coefficients (ICC) were used to evaluate agreement and the Wilcoxon signed-rank test, to test statistical significance between measurement techniques. Results Forty post-STEMI patients (mean age 58.3± 9.37 years) were studied. There was moderate agreement between MAG and PSIR techniques in both the acute phase (ICC 0.74, 95% CI [0.56, 0.85]) and in the chronic phase (ICC 0.67, 95% CI [0.46, 0.81]). In the acute phase, MAG yielded a lower median scar mass (24.6 g [interquartile range (IQR): 10.6–33.0] compared with PSIR 34.9 g [IQR: 18.8–50.5], p<0.001). Similarly, in the chronic phase, MAG yielded a lower median scar mass (12.9 g [IQR: 7.1–19.0] versus 20.3 g [IQR: 12.6–28.2], respectively, p<0.001, figure 1 and table 1). Conclusion Following STEMI, there is a significant difference in CMR-assessed scar mass as measured by MAG and PSIR techniques, with PSIR reporting higher scar mass in both acute and chronic phases. Scar quantification by MAG and PSIR images should not be used interchangeably. Conflict of Interest No