The sensitivity and specificity of FDG PET in distinguishing recurrent brain tumor from radionecrosis in patients treated with stereotactic radiosurgery

Radiation necrosis and recurrent brain tumor have similar symptoms and are indistinguishable on both magnetic resonance imaging (MRI) and computed tom ograph scans. F-18-fluorodeoxyglucose (FDG) positron emission tomography (P ET) has been proposed as a diagnostic alternative, particularly when co-reg istered with MRT. We studied 47 patients with brain tumors treated with ste reotactic radiosurgery and followed with FDG PET. For all tumor types, the sensitivity of FDG PET for diagnosing tumor was 75% and the specificity was 81%. For brain metastasis without MRI co-registration, FDG PET had a sensi tivity of 65% and a specificity of 80%. For brain metastasis with MRI co-re gistration, FDG PET had a sensitivity of 86% and specificity of 80%. MRI co registration appears to improve the sensitivity of FDG PET, making it a use ful modality to distinguish between radiation necrosis and recurrent brain metastasis. (C) 2001 Wiley-Liss, Inc.