BOLD effect on calf muscle groups in elderly females with different bone mineral density

This study examined the BOLD effect on calf muscles in elderly subjects with different bone mineral density. The purpose was to investigate the oxygenation characteristics in different calf muscle groups for the elderly females and compare the muscle oxygenation among groups with different bone mineral density. Temporary vascular occlusion was induced with air-cuff compression of the thigh and BOLD-MRI data curve was fitted to derive quantitative parameters. Three muscle groups, gastrocnemius muscle (lateral head), soleus muscle, and tibialis anterior muscle, were investigated individually. Quantitative CT measurement was conducted on each subject, based on which subjects were classified into normal, osteopenia, and osteoporosis groups. The BOLD signal in soleus muscle showed the lowest minimum ischemic value during ischemia and the steepest slope during hyperemia. As soleus muscle is mainly composed by slow-twitch oxidative muscle fibers, current results may be due to a higher vascular bed density and better endothelial function in such muscle. By t-test, the half-life of the BOLD signal decay during ischemia in both gastrocnemius and soleus muscles was significantly prolonged in osteoporosis group, indicating a degenerated muscular oxygen metabolic capacity in osteoporotic patients.