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

PurposeTo 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 MethodsIn 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. ResultsIn 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: 956.344.4 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 (<33 years) global native T-1 was higher in females than in males at 1.5T (960.0 +/- 20.3 vs. 931.5 +/- 22.2 msec, respectively; P=0.003) and 3.0T (1166.5 +/- 19.7 vs. 1130.2 +/- 20.6 msec; P < 0.001). No sex differences were observed in upper age tertile (55 years) at 1.5T (937.7 +/- 25.4 vs. 934.7 +/- 22.3 msec; P=0.762) or 3.0T (1153.0 +/- 30.0 vs. 1132.3 +/- 23.5 msec; P=0.056). Association of global native T-1 to age (P=0.002) and sex (P < 0.001) was independent of field strength and body size. ConclusionIn healthy adults, native T-1 values are highest in the ventricular septum. Global native T-1 was inversely associated with age in women, but not in men. J. Magn. Reson. Imaging 2016;44:541-548.