Résumé : BACKGROUND AND PURPOSE: Management of patients with low-grade glioma is a major challenge for the neurosurgeon. When is neurosurgery indicated? Should chemotherapy or radiotherapy be used? Many questions without an answer. We reviewed our experience with 65 patients treated for low-grade glioma who had preoperative PET images (FDG or/and MET). We examined the prognostic value of PET and also determined the sensitivity and the specificity of PET images to predict outcome. METHODS: Sixty-five patients with a FDG or MET PET images were analyzed. We used two visual scales and had complete follow-up data for 63 patients. The free interval was the principal criterion for statistical analysis. The sensitivity and the specificity of PET images was determined. RESULTS: Strong FDG uptake was correlated with a short free interval (p=0.001). Similar results were found with the MET analysis (p=0.0076). We had a PET with MET and FDG for 36 patients. The sensitivity was 66% and the specificity 94% for FDG PET. Sensitivity was 100% and specificity 53% for MET PET. CONCLUSIONS: PET imaging provides a prognostic factor independent from histology. MET PET is the best exam for the follow-up of patients with low-grade glioma and is helpful for separating aggressive from low-grade glioma.