Age-related changes in skeletal muscle as detected by diffusion tensor magnetic resonance Imaging

Background. Loss of muscle mass and strength is a common symptom in the elderly population. This is partly a result of the structural changes that occur during the aging process. We applied diffusion tenser magnetic resonance imaging (DTMRI) to determine if water diffusivity in skeletal muscle changes with age. Methods. Thirty-eight healthy men, ranging from 27 to 67 years of age, were recruited for this study. The total population was grouped by age (Young < mean age 46.4: n = 20; Old >= mean age 46.4: n = 18) and body mass index (BMI; Normal < 25: n = 20; Over >= 25: n = 18). The principal, second, and third eigenvalues (lambda(1) >= lambda(2) >= lambda(3)), and fractional anisotropy (FA), were calculated from the diffusion tenser of the soleus, lateral and medial gastrocnemius, and anterior tibialis (AT). Analyses included comparison of groups and linear regressions. Results. The older adults showed a significant reduction in the eigenvalues of the plantar flexors (similar to 7%, p < .05) and FA of AT (similar to 10%, p < .05) from that of the younger adults. No age differences were observed in the FA of the plantar flexors or eigenvalues of AT. lambda(1) and lambda(2) had a linear dependence on age in the plantar flexors, whereas AT showed age dependence in lambda(3) and FA. Conclusions. We demonstrated that DTMRI is sensitive to age-related changes in muscle, and that the effects of aging differ between the plantar flexors and AT.