BACKGROUND: Late gadolinium enhancement (LGE) images, reconstructed using magnitude (MAG) or phase-sensitive inversion recovery (PSIR), differ in signal intensities due to their handling of longitudinal magnetization. These differences influence LGE quantification, which typically uses Full Width at Half Maximum (FWHM) or standard deviation (n-SD) thresholding when predicting cardiac events. OBJECTIVE: This study assessed the impact of FWHM and n-SD on MAG- and PSIR-derived scar characteristics. METHODS: Ischemic cardiomyopathy (ICM) patients undergoing LGE imaging were retrospectively studied. Two reconstruction techniques (MAG vs. PSIR) and two thresholding methods (FWHM vs. n-SD) were evaluated. LGE images were post-processed with commercially available software, using scar thresholds of 40-60% maximum signal intensity (FWHM) and 2-5 standard deviations above the mean (n-SD). Scar quantification was compared between primary and secondary prevention implantable cardioverter defibrillator (ICD) patients. RESULTS: Among 80 patients, 32 (40%) had an ICD for primary prevention. PSIR imaging showed significantly larger scar metrics than MAG using FWHM and n-SD thresholding, including greater border zone (BZ) (16.43 ± 8.15g vs. 21.42 ± 10.72g, p<
0.001) and conduction corridor (CC) characteristics. MAG analysis revealed significant differences in scar and CC metrics. For PSIR, scar metrics were consistent across FWHM and n-SD. MAG-based analysis showed larger BZ and CC length in primary prevention patients, with similar trends for PSIR. CONCLUSION: This study demonstrates significant differences in myocardial scar metrics based on reconstruction and thresholding techniques. PSIR consistently provided robust scar characterization across methods, emphasizing its clinical potential to standardize LGE-CMR workflows and improve ventricular arrhythmia risk stratification.