La tomographie à émission de positons (TEP) permet de mesurer la distribution d'un traceur du métabolisme respectivement dans une tumeur et dans le tissu cérébral présumé sain. Cette technique d'imagerie apporte des informations complémentaires de celles obtenues par l'imagerie anatomique (scanner, IRM) et de l'examen histologique d'une pièce de biopsie. Les traceurs les plus utilisés en neuro-oncologie sont le 18FDG et la 11C-méthionine. Toutefois, dans les différentes applications de la méthode, il apparaît que le second traceur est plus sensible et spécifique que le premier. Les principales indications de la TEP en neuro-oncologie clinique sont les suivantes

Positron emission tomography (PET) assesses the uptake and distribution of a radiopharmaceutics labelling tissue metabolism, in tumour and in presumably healthy brain, respectively. This technique provides data which are complementary from those obtained with anatomical imaging (CT-scanner, MRI) and with histology performed on a biopsy sample. The most frequently used tracers, in neuro-oncology, are 18FDG and 11C-methionine. However, for most of the applications of this technique, the latter tracer appears to be more effective than the former, both from the point of view of sensitivity and specificity. The main applications of PET in clinical neuro-oncology are the following

• when establishing the early diagnosis of a glioma, in order to differentiate between cell lines (astrocytoma or oligodendroglioma) and grading;
• during the follow-up of the tumour, in order to identify progression from a low grade towards an anaplastic lesion;
• after surgical removal, to exhibit some residual tumour;
• after radiation therapy or chemotherapy, for an early assessment of the response to therapy;
• long after treatment, to differentiate between radiation necrosis and tumour recurrence.