New imaging modalities permit detailed knowledge of the anatomy of cerebral arteriovenous malformations. Magnetic resonance imaging (MRI) provides morphological data, size and topography of the nidus, anatomic relationship, as well as dynamic information particularly with the use of MR angiography. Selective and hyperselective cerebral angiography provide information about the angioarchitecture and search for associated vascular abnormalities such as aneurysms. It is therefore possible to distinguish malformations associated with a high risk of hemorrhage and to define the indications for radiosurgery.