Calf muscles at blood oxygen level-dependent MR imaging: aging effects at postocclusive reactive hyperemia

PURPOSE: To prospectively investigate age-related changes in muscle reperfusion by using blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging of the calf in young and elderly healthy volunteers during postocclusive reactive hyperemia. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Eleven healthy elderly (mean age, 64.0 years +/- 6.4 [standard deviation]; six men, five women) and 17 healthy young volunteers (mean age, 30.3 years +/- 6.5; seven men, 10 women) underwent muscle BOLD MR imaging of the calf. A fat-suppressed T2*-weighted single-shot multiecho echo-planar imaging sequence was used. Temporary vascular occlusion was induced with suprasystolic cuff compression of the thigh. T2* time courses of the muscle BOLD MR signal intensity were obtained from four calf muscles and were characterized by the following curve parameters: hyperemia peak value, time to peak, and T2* end value after 360 seconds of hyperemia. Differences in these parameters between the two cohorts were assessed by using a Student t test. RESULTS: Considerably lower T2* maxima were observed in the elderly group during hyperemia (P < .005), with a mean hyperemia peak value of 13.1% +/- 3.0 compared with 18.9% +/- 4.8 in young healthy adults. Peaking occurred earlier in the elderly group (P < .05), with a mean time to peak of 32.2 seconds +/- 10.6 compared with 43.1 seconds +/- 10.7 in young adults. Furthermore, the elderly group had a significantly slower decrease of the muscle BOLD signal after the hyperemia peak (P < .001), which led to a higher end value of 8.6% +/- 3.0 compared with 2.6% +/- 2.1 in the young group. CONCLUSION: BOLD MR imaging results of the calf demonstrated statistically significant age-dependent differences in the rate, intensity, and recovery of the postocclusive muscle BOLD signal.