Human Skeletal Muscle: Sodium MR Imaging and Quantification—Potential Applications in Exercise and Disease

Publisher Website
Google Scholar
Abstract
PURPOSE: To use sodium 23 magnetic resonance (MR) imaging to quantify noninvasively total sodium in human muscle and to apply the technique in exercise and musculoskeletal disease. MATERIALS AND METHODS: Total [Na] sodium was determined from the ratio of the relaxation-corrected 23Na signal intensities measured from short echo-time (0.4 msec) 23Na images to those from an external saline solution reference. The method was validated with the blinded use of saline solutions of varying sodium concentrations. [Na] was measured in the calf muscles in 10 healthy volunteers. 23Na MR imaging also was performed in two healthy subjects after exercise, two patients with myotonic dystrophy, and two patients with osteoarthritis. RESULTS:23Na MR imaging yielded a total [Na] value of 28.4 mmol/kg of wet weight ± 3.6 (SD) in normal muscle, consistent with prior biopsy data. Spatial resolution was 0.22 mL, with signal-to-noise ratio of 10–15. Mean signal intensity elevations were 16% and 22% after exercise and 47% and 70% ...