USE OF POSITRON EMISSION TOMOGRAPHY (PET) IN STEREOTAXIC CONDITIONS FOR BRAIN BIOPSY

In order to take advantage of the metabolic information provided by po sitron emission tomography (PET) in cases of brain tumour, we have dev eloped a technique to integrate PET images routinely in the planning o f stereotactic brain biopsy. We used stereotactic PET with [F-18]-labe lled fluorodeoxyglucose (PET-FDG) in 38 patients undergoing brain biop sy. To evaluate the contribution of PET-FDG in guiding brain biopsy, w e analyzed the diagnosis provided by the 78 stereotactic trajectories obtained in these patients. We found that stereotactic PET-FDG seemed to provide more information in cases of anaplastic astrocytomas and gl ioblastomas than in low-grade gliomas. Our results also show that biop sy trajectories performed in areas where increased FDG uptake is found within the lesion boundaries always provide interpretable specimens; this was not the case for trajectories guided by CT only. Therefore, t he routine integration PET-FDG in the planning of stereotactic brain b iopsy may lead to a reduction in sampling. Recently, we also tested co nsecutive stereotactic PET with [C-11]-labelled methionine (PET-Met) a nd PET-FDG. This technique allowed us to compare accurately the tumour al glucose metabolism and protein synthesis. Our results suggest that stereotactic PET may increase the diagnostic yield of brain biopsy and may improve the understanding of PET in neuro-oncology.