Inter-site Variability of Myocardial Native T1 Mapping Values of 3t Cardiac Magnetic Resonance

Background Native T1 mapping by cardiovascular magnetic resonance (CMR) is a promising quantitative technique for the non-invasive characterization of myocardial tissue. However, its broad clinical application is hampered by significant variability in reported T1 values across different scanners and institutions. Hence, this study aimed to evaluate and to compare the inter-site variability of native T1 values of 3T CMR among healthy subjects from two different tertiary hospitals. Methods This retrospective study included a total of 36 healthy subjects from two tertiary hospitals (as Site A: n = 25; and Site B: n = 11). Native T1 values were systematically measured from basal, mid, and apical short-axis ventricular slices, segmented according to the 16-segment American Heart Association (AHA) model. Global, regional, and septal T1 values were statistically compared between the two sites. Multivariable analysis was performed to determine if differences persisted after adjusting for potential confounders such as heart rate, age, and sex. Results A significant and substantial difference in global myocardial native T1 was observed, with Site A exhibiting markedly lower values than Site B (1163.36 ± 36.40ms vs. 1225.39 ± 20.39ms, respectively; p < 0.001). Both centers demonstrated regional heterogeneity in T1 values; however, the patterns differed. Site A showed a quadratic trend with the highest T1 values at the apex (1184.96 ± 80.72ms), whereas Site B exhibited a linear increase from base (1216.55 ± 22.57ms) to apex (1245.27 ± 31.34ms). The inter-site T1 differences remained highly significant after adjusting for age, sex, and heart rate. Conclusion The results emphasized the need for protocol harmonization and site-specific reference ranges to ensure reliable T1 mapping interpretation in multi-center settings.