Native myocardial longitudinal (T1 ) relaxation time: Regional, age, and sex associations in the healthy adult heart

Purpose To use magnetic resonance imaging (MRI) at two field strengths to assess healthy adults' regional myocardial noncontrast (native) T 1 relaxation time distribution, and global myocardial native T 1 between sexes and across age groups. Materials and Methods In all, 84 healthy volunteers underwent MRI at 1.5T and 3.0T. T 1 maps were acquired in three left ventricular short axis slices using an optimized modified Look–Locker inversion recovery investigational prototype sequence. T 1 measurements in msec were calculated from 16 regions‐of‐interest, and a global T 1 value from all evaluable segments per subject. Associations were assessed with a multivariate linear regression model. Results In total, 1297 (96.5%) segments were evaluable at 1.5T and 1263 (94.0%) segments at 3.0T. Native T 1 was higher in septal than lateral myocardium (1.5T: 956.3 ± 44.4 vs. 939.2 ± 54.2 msec; P < 0.001; 3.0T: 1158.2 ± 45.9 vs. 1148.9 ± 56.9 msec; P = 0.012). Native T 1 decreased with increasing age in females but not in males. Among lowest age tertile (