Uptake of 18F-Labeled 6-Fluoro-6-Deoxy-D-Glucose by Skeletal Muscle Is Responsive to Insulin Stimulation

We are developing a methodology for the noninvasive imaging of glucose transport in vivo with PET and (18)F-labeled 6-fluoro-6-deoxy-d-glucose ((18)F-6FDG), a tracer that is transported but not phosphorylated. To validate the method, we evaluated the biodistribution of (18)F-6FDG to test whether it is consistent with the known properties of glucose transport, particularly with regard to insulin stimulation of glucose transport. Under glucose clamp conditions, rats were imaged at the baseline and under conditions of hyperinsulinemia. The images showed that the radioactivity concentration in skeletal muscle was higher in the presence of insulin than at the baseline. We also found evidence that the metabolism of (18)F-6FDG was negligible in several tissues. (18)F-6FDG is a valid tracer that can be used in in vivo transport studies. PET studies performed under glucose clamp conditions demonstrated that the uptake of nonphosphorylated glucose transport tracer (18)F-6FDG is sensitive to insulin stimulation.