Sequence-dependent variability of native myocardial T1: a comparative study of MOLLI 5(3)3 and SMART1Map in pediatric and adult cohorts

Purpose Among cardiac T1 mapping techniques, Modified Look-Locker Inversion recovery (MOLLI) 5(3)3 and Saturation Method using Adaptive Recovery Times (SMART1Map) are widely used, yet their comparative behavior across age groups and their sensitivity to clinical and cardiac functional parameters remain insufficiently characterized. This study aimed to compare MOLLI 5(3)3 and SMART1Map native T1 measurements and to evaluate the influence of age, anthropometric variables, and cardiac functional indices in pediatric and adult populations. Methods Sixty-four healthy volunteers, including pediatric (n = 27) and adult (n = 37) subjects, underwent cardiac magnetic resonance at 1.5 T using both MOLLI 5(3)3 and SMART1Map sequences. Regional and segmental myocardial T1 values were quantified and analyzed according to the AHA model. Associations between T1 values and clinical as well as cardiac functional parameters were assessed using correlation analysis. Results SMART1Map systematically yielded higher regional and segmental T1 values than MOLLI across all myocardial locations ( p < 0.001). With MOLLI, significant age-group differences were observed at the basal ( p = 0.045) and apical ( p = 0.006) levels, and in the basal anterolateral ( p = 0.007), mid-inferolateral ( p = 0.028) and anterolateral ( p = 0.007) segments. In contrast, SMART1Map showed a significant age-related difference only in the apical lateral segment ( p = 0.007). A significant sex × age interaction was observed for MOLLI-derived T1 values at the apical level, whereas SMART1Map showed no sex-dependent effects. Several nominal correlations were observed between MOLLI-derived T1 values and right ventricular functional parameters; however, none remained significant after correction for multiple comparisons. The relatively modest cohort size limits the statistical power to detect weak associations, particularly after correction for multiple comparisons. SMART1Map -derived T1 values demonstrated minimal association with ventricular functional indices across both age groups. Conclusion MOLLI 5(3)3 demonstrates greater sensitivity to age and cardiac functional variability, particularly in adult subjects, whereas SMART1Map provides more stable native T1 estimates across myocardial regions and age groups. These findings suggest that SMART1Map may provide more stable estimates for native myocardial T1 mapping in clinical and research settings where measurement consistency is prioritized.