Atlas of non-pathological solitary or asymmetrical skeletal muscle uptake in [(18)F]FDG-PET

Positron emission tomography (PET) using 2-deoxy-2-[(18)F]fluoro-d-glucose ([(18)F]FDG) is widely used in oncology and other fields. In [(18)F]FDG PET images, increased muscle uptake is observed owing exercise load or muscle tension, in addition to malignant tumors and inflammation. Moreover, we occasionally observe non-pathological solitary or unilateral skeletal muscle uptake, which is difficult to explain the strict reason. In most cases, we can interpret them as not having pathological significance. However, it is important to recognize such muscle uptake patterns to avoid misdiagnoses with pathological ones. Therefore, the teaching point of this pictorial essay is to comprehend the patterns of solitary or asymmetrical skeletal muscle uptake seen in routine [(18)F]FDG-PET scans. As an educational goal, you will be able to mention muscles where intense physiological [(18)F]FDG uptake can be observed, differentiate between physiological muscle uptake and lesion, and discuss with any physicians or specialists about uncertain muscle uptake.