MR Imaging Relaxation Times of Abdominal and Pelvic Tissues Measured in Vivo at 3.0 T: Preliminary Results

PURPOSE: To measure T1 and T2 relaxation times of normal human abdominal and pelvic tissues and lumbar vertebral bone marrow at 3.0 T. MATERIALS AND METHODS: Relaxation time was measured in six healthy volunteers with an inversion-recovery method and different inversion times and a multiple spin-echo (SE) technique with different echo times to measure T1 and T2, respectively. Six images were acquired during one breath hold with a half-Fourier acquisition single-shot fast SE sequence. Signal intensities in regions of interest were fit to theoretical curves. Measurements were performed at 1.5 and 3.0 T. Relaxation times at 1.5 T were compared with those reported in the literature by using a one-sample t test. Differences in mean relaxation time between 1.5 and 3.0 T were analyzed with a two-sample paired t test. RESULTS: Relaxation times (mean ± SD) at 3.0 T are reported for kidney cortex (T1, 1,142 msec ± 154; T2, 76 msec ± 7), kidney medulla (T1, 1,545 msec ± 142; T2, 81 msec ± 8), liver (T1, 809 msec ± 71; T2, 34 msec ± 4), spleen (T1, 1,328 msec ± 31; T2, 61 msec ± 9), pancreas (T1, 725 msec ± 71; T2, 43 msec ± 7), paravertebral muscle (T1, 898 msec ± 33; T2, 29 msec ± 4), bone marrow in L4 vertebra (T1, 586 msec ± 73; T2, 49 msec ± 4), subcutaneous fat (T1, 382 msec ± 13; T2, 68 msec ± 4), prostate (T1, 1,597 msec ± 42; T2, 74 msec ± 9), myometrium (T1, 1,514 msec ± 156; T2, 79 msec ± 10), endometrium (T1, 1,453 msec ± 123; T2, 59 msec ± 1), and cervix (T1, 1,616 msec ± 61; T2, 83 msec ± 7). On average, T1 relaxation times were 21% longer (P < .05) for kidney cortex, liver, and spleen and T2 relaxation times were 8% shorter (P < .05) for liver, spleen, and fat at 3.0 T; however, the fractional change in T1 and T2 relaxation times varied greatly with the organ. At 1.5 T, no significant differences (P > .05) in T1 relaxation time between the results of this study and the results of other studies for liver, kidney, spleen, and muscle tissue were found. CONCLUSION: T1 relaxation times are generally higher and T2 relaxation times are generally lower at 3.0 T than at 1.5 T, but the magnitude of change varies greatly in different tissues.