REGIONAL METHIONINE AND GLUCOSE-UPTAKE IN HIGH-GRADE GLIOMAS - A COMPARATIVE-STUDY ON PET-GUIDED STEREOTAXIC BIOPSY

Gliomas are regionally heterogeneous tumors. The local relationship be tween histologic features and radiotracer uptake evaluated by PET shou ld therefore influence analysis and interpretation of PET results on g liomas, This study explored this local relationship as a result of PET guidance of stereotactic biopsies. Methods: Local histology was confr onted to the regional uptake of F-18-2-fluoro-2-deoxy-D-glucose (F-18- FDG) and C-11-methionine (C-11-MEF) in 14 patients with high-grade gli oma diagnosed during a procedure of PET-guided stereotactic biopsies, We analyzed the uptake of both tracers in regions of interest centered on the stereotactic coordinates of 93 biopsy samples. Results: A semi quantitative analysis revealed a significant regional correlation betw een C-11-MET and F-18-FDG uptakes. Uptake of both tracers was signific antly higher on the site of tumor samples showing anaplastic changes t han in the rest of the tumor. Presence of necrosis in anaplastic areas of the tumor significantly reduced the uptake of C-11-MET, Conclusion : PET with C-11-MET and F-18-FDG may help to evaluate, in vivo, the me tabolic heterogeneity of human gliomas, Anaplasia is a factor of incre ased uptake of both tracers, but microscopic necrosis in anaplastic ar eas influences their uptake differently, This finding probably relates to the differences in tracer uptake by non-neoplastic components of n ecrotic tumors. These results underline the complementary role oF F-18 -FDG and C-11-MET for the study of brain tumors and favors their use f or stereotactic PET guidance of diagnostic or therapeutic procedures.