The investigators suggest using a well-known analysis software (Scenium software, Siemens GmbH) who allows an automated analysis by the distribution of the cerebral metabolism by means of the F18-FDG TEP-TDM and a quantitative measure, expressed in regional consumption of glucose expressed by g / 100 g / min for every 18F-FDG TEP-TDM and for every region of interest. Image registering by the camera, remote of the injection of the tracer, lasts less than 10 minutes.The software also allows to compare the data acquired for a patient with a standardized database.