FDG hypermetabolism associated with inflammatory necrotic changes following radiation of meningioma.

Abstract

PET with 18F-fluoro-2-deoxy-D-glucose (FDG) is currently the noninvasive gold standard for distinguishing brain tumor recurrence from radiation necrosis. We present a case report that appears to contradict this doctrine. The patient had a history of atypical meningioma and was treated with surgical resection and postoperative proton-beam radiation therapy. Approximately 16 mo after completion of therapy, MRI demonstrated two new regions of enhancement, and an FDG-PET study was performed to further characterize these lesions. FDG-PET demonstrated an area of intense hypermetabolism, and wide surgical resection was performed. Histological examination of the surgical specimen revealed reactive changes and areas of necrosis. There was no evidence of either recurrent or radiation-induced tumor.