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Calf Muscles at Blood Oxygen Level–Dependent MR Imaging: Aging Effects at Postocclusive Reactive Hyperemia¹

¹ From the Biocenter, University of Basel, Basel, Switzerland (A.C.S.); and Departments of Angiology (M.A.) and Radiology (D.B.), University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland. Received May 11, 2007; revision requested July 16; revision received September 25; accepted October 16; final version accepted October 30. D.B. supported by Swiss National Science Foundation Project No. SNF 3100A0-100633. Address correspondence to D.B. (e-mail: dbilecen{at}uhbs.ch).

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.

© RSNA, 2008