N. Nakayama

BACKGROUND AND PURPOSE: Positron-emission tomography (PET) is a useful tool in oncology. The aim of this study was to assess the metabolic activity of gliomas using 11C-methionine (MET), [18F] fluorodeoxyglucose (FDG), and 11C-choline (CHO) PET and to explore the correlation between the metabolic activity and histopathologic features. MATERIALS AND METHODS: PET examinations were performed for 95 primary gliomas (37 grade II, 37 grade III, and 21 grade IV). We measured the tumor/normal brain uptake ratio (T/N ratio) on each PET and investigated the correlations among the tracer uptake, tumor grade, tumor type, and tumor proliferation activity. In addition, we compared the ease of visual evaluation for tumor detection. RESULTS: All 3 of the tracers showed positive correlations with astrocytic tumor (AT) grades (II/IV and III/IV). The MET T/N ratio of oligodendroglial tumors (OTs) was significantly higher than that of ATs of the same grade. The CHO T/N ratio showed a significant positive correlation with histopathologic grade in OTs. Tumor grade and type influenced MET uptake only. MET T/N ratios of more than 2.0 were seen in 87 % of all of the gliomas. All of the tracers showed significantly positive correlations with Mib-1 labeling index in ATs but not in OTs and oligoastrocytic tumors. CONCLUSION: MET PET appears to be useful in evaluating grade, type, and proliferative activity of ATs