A 59-year-old man with thymic carcinoma underwent Tc-99m MIBI myocardial SPECT, and Tc-99m MIBI uptake in the mass was unexpectedly found in a planar image. SPECT images of the thorax showed an increased uptake area with central photon deficiency (a ring-like appearance), which reflected central tumor irreversible ischemia or progressing necrosis with peripheral viable tumor tissue.