Imaging of skeletal muscle function using (18)FDG PET: force production, activation, and metabolism

The purpose of this study was to determine whether [F-18]fluoradeoxyglucose (FDG) positron emission tomography (PET) can be used to evaluate muscle fo rce production, create anatomic images of muscle activity, and resolve the distribution of metabolic activity within exercising skeletal muscle. Seven teen subjects performed either elbow flexion, elbow extension, or ankle pla ntar flexion after intravenous injection of FDG. PET imaging was performed subsequently, and FDG uptake was measured in skeletal muscle far each task. A fivefold increase in resistance during elbow flexion increased FDG uptak e in the biceps brachii by a factor of 4.9. Differences in relative FDG upt ake were demonstrated as exercise tasks and loads were varied, permitting d ifferentiation of active muscles. The intramuscular distribution of FDG wit hin exercising biceps brachii varied along the transverse and longitudinal axes of the muscle; coefficients of variation along these axes were 0.39 an d 0.23, respectively. These findings suggest FDG PET is capable of characte rizing task-specific muscle activity and measuring intramuscular variations of glucose metabolism within exercising skeletal muscle.