[Contribution of imaging in the diagnosis and follow-up of brain tumors].

With the use of modern radiological imaging (US, CT-scan, MRI), the most important informations to recognize a tumor remain the morphological features (localization, size, extension, number of lesions...). The precision of these informations is constantly improved (use of contrast medium, various slices angulations...) and in this field, MRI is the most precise examination. Moreover, these less aggressive investigations allow a repeated and more efficient therapeutic follow-up. In contrast with initial expectations, these radiological investigations do not always allow a formal histological characterization of the different tumor types of the central nervous system, even if some intratumoral components are recognized (fat, calcifications, liquids...).