Plain radiography or CT can only detect abnormalities when there is destruction in the trabecular bone or cortical bone. Technetium-99m methylene diphosphonate (Tc-MDP) bone scintigraphy is an imaging diagnostic method that indirectly evaluates the state of the bone marrow, but it cannot accurately describe it anatomically, and it has the disadvantage of low specificity. Also, lesions that do not cause an osteoblastic reaction are difficult to detect on bone scintigraphy. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is a useful imaging diagnostic method for evaluating primary lesions, lymph node invasion, and metastatic cancer through abnormalities in the metabolic function of the bone marrow.