[en] Technetium 99m methoxyisobutylisonitrile (Tc-99m-MIBI) is a new tracer developed for the diagnosis of ischemic heart disease. We have reported the feasibility of Tc-99m-MIBI single photon emission computed tomography (SPECT) in evaluating the malignancy and the viability of the brain tumors. In this study, the authors investigated the role of Tc-99m-MIBI SPECT in the diagnosis of recurrent malignant brain tumor and radiation necrosis. We examined 20 adult patients with malignant brain tumors using Tc-99m-MIBI SPECT. All patients underwent surgery and radiation therapy. Recurrent malignant tumor showed high uptake of Tc-99m-MIBI while radiation necrosis revealed relative low uptake of Tc-99m-MIBI. However, there were false negative and positive cases. The group with TTP less than 12 month showed high uptake of Tc-99m-MIBI. The general behavior of Tc-99 m-MIBI was almost same as that of 201-Tl, however, the image resolution of Tc-99m-MIBI was better than that of 201-Tl. Tc-99m-MIBI SPECT had limitations in the histological diagnosis of recurrent tumor, however it was useful for the estimation of the prognosis. (author)