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

Abstract

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: 956.3 ± 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 (<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.

Normal values of native T1 and T2 relaxation times on 3T cardiac MR in a healthy pediatric population aged 9–18 years

“…The lack of influence of age on the native T 1 and T 2 relaxation time values in our study could derive from the fact that, unlike in studies on adult populations, we analyzed only a small age range (11 years). 10,15,17 Mean T 1 relaxation time in children seems to be higher and T 2 relaxation time similar in comparison with those studies. 14 We have found that in children T 1 relaxation time was not influenced by sex, but T 2 relaxation time was higher in female than in male children.…”

“…16 Until now, it was unknown whether pubertal status could influence T 1 and T 2 relaxation times. 15,16 We found no difference in T 1 and T 2 relaxation times between the studied group of boys and our adult reference group of middle-aged males. The lack of influence of age on the native T 1 and T 2 relaxation time values in our study could derive from the fact that, unlike in studies on adult populations, we analyzed only a small age range (11 years).…”

“…1,2 In most studies, septal T 1 and T 2 relaxation times were higher than in other segments, 3,15 and are therefore most likely to represent the upper spectrum of possible T 1 and T 2 relaxation time values. This is a commonly used practice as, it reduces the time of analysis, improves the repeatability of assessment in comparison to global analysis, which averages T 1 and T 2 relaxation times taken from 16 segments.…”

“…In adult populations native T 1 values were most commonly influenced by sex (higher in females), 10,[12][13][14][15]21 age (increase or decrease), 12,13,17 and heart rate. 14,15 Also, the influence of heart rate has not been unequivocally reproduced. Some studies did not find any difference in native T 1 relaxation time according to sex 3,17 or age, 3,16 while others reported that age influenced T 1 values only in females.…”

“…1,9 Use of mapping techniques requires accurate knowledge of normal ranges. 3,4,[12][13][14][15][16][17] Therefore, the aim of our study was to present limited normal values of native T 1 and T 2 mapping relaxation times in healthy pediatric subjects of different age and sex. [10][11][12] In recent years, there have been reports presenting established normal values for T 1 and T 2 , but none of them included pediatric populations.…”