Noncontrast skeletal muscle oximetry

Purpose The objective of this study was to develop a new noncontrast method to directly quantify regional skeletal muscle oxygenation. Methods The feasibility of the method was examined in five healthy volunteers using a 3 T clinical MRI scanner, at rest and during a sustained isometric contraction. The perfusion of skeletal muscle of the calf was measured using an arterial spin labeling method, whereas the oxygen extraction fraction of the muscle was measured using a susceptibility-based MRI technique. Results In all volunteers, the perfusion in soleus muscle increased significantly from 6.5 ± 2.0 mL (100 g min)^-1 at rest to 47.9 ± 7.7 mL (100 g min) ^-1 during exercise (P < 0.05). Although the corresponding oxygen extraction fraction did not change significantly, the rate of oxygen consumption increased from 0.43 ± 0.13 to 4.2 ± 1.5 mL (100 g min) ^-1 (P < 0.05). Similar results were observed in gastrocnemius muscle but with greater oxygen extraction fraction increase than the soleus muscle. Conclusion This is the first MR oximetry developed for quantification of regional skeletal muscle oxygenation. A broad range of medical conditions could benefit from these techniques, including cardiology, gerontology, kinesiology, and physical therapy.