28 Sex- and age-differences in native t1 relaxation times in healthy adults at 1.5 and 3.0 tesla

Abstract

<h3>Background</h3> Limited information is available on sex differences in myocardial T1 relaxation times over age ranges. We used cardiac magnetic resonance (CMR) imaging at two field strengths to assess myocardial T1. <h3>Methods</h3> Healthy adults underwent CMR at 1.5 Tesla (T) (Avanto) and 3.0 T (Verio). T1 maps were acquired in three short axis slices, using an optimised MOLLI investigational prototype sequence (Siemens Healthcare WIP 448). Global mean T1, in milliseconds (ms), was calculated from evaluable regions-of-interest using 16-segment model. <h3>Results</h3> 84 volunteers (43 male) underwent scans 1.4 ± 1.4 days apart. Because of artefacts related to cardio-respiratory motion and susceptibility effects, 47 (3.9%) segments were excluded at 1.5 T and 81 (6.3%) segments at 3.0 T, with a preponderance occurring at the distal slice. Age-related decrease in T1 was observed in females, whereas male T1 remained reasonably constant (Figure 1 and Table 1). At 1.5 T, amongst those &lt;40 years T1 was higher for females (961.3 ± 19.3 ms) than males (932.0 ± 22.8 ms, p &lt; 0.001), whereas there was no difference in those ≥60 years (937.2 ± 28.7 vs. 934.3 ± 24.3 ms, respectively, p = 0.807). Results were similar at 3.0 T; female T1 was higher at &lt;40 years (1166.0 ± 41.7 vs. 1139.6 ± 26.1 ms, p = 0.044), but not at ≥60 years (1151.0 ± 39.3 vs. 1124.3 ± 31.6 ms, p = 0.087). Regression analysis shows that at 1.5 T average T1 decreases by 5.13 ms for each additional decade (p = 0.038). An identical trend was observed at 3.0 T, with regression coefficient −0.564 ms/year approaching statistical significance (p = 0.064). <h3>Conclusions</h3> In healthy adults, sex difference in global myocardial mean T1 relaxation times are observed amongst younger. This pattern is consistent across CMR field strengths. Pre- vs. post-menopausal differences in myocardial structure and function of females may explain these differences and this possibility merits further assessment.