Application of positron emission tomography in physical medicine

Positron emission tomography (PET) is widely used in the fields of clinical and basic medicine. The PET device utilizes coincidence logic to detect annihilation photons emitted from positrons and estimates physiological functions of human organs in vivo. Radiopharmaceutical 18F- fluorodeoxyglucose (FDG), an analogue of glucose, is trapped metabolically in cells after being administered into the body, and can be substantially used for evaluating physiological and biochemical functions in vivo. Here, we attempted to describe the basics of PET as well as to apply the technique together with 18F-FDG as a tracer for evaluating organ glucose metabolism induced by exercise. Three-dimensional (3D) FDG-PET was applied to normal volunteers who performed exercise to evaluate whole-body glucose metabolism. Regions of interest analysis were drawn on visually defined regions (i.e., lower limbs, thigh, liver, intestine, brain, heart, etc.) to determine radioactivity distribution. FDG-PET clearly showed the recruitment of energy resources from abdominal organs to lower limb skeletal muscles to balance energy expenditures. The results suggested that 3D FDG-PET can be applied as an imaging tool to physical medicine.