[Is magnetic resonance the first indication in neurologic imaging?].

Various methods of neuroradiologie examination are described, with an emphasis on recent developments, in particular in CT scan (angioscan, spiral acquisition) and MRI. CT scan, which is the most accessible method, can answer most questions in intracerebral emergencies (trauma, vascular accidents, intracerebral hypertension ...). Outside the emergency setting, morphological study of the brain by MRI is much superior to that provided by CT scan and should be the first-line examination for investigation of suspected tumour, wite matter lesion.... This is even more evident in exploration of lesions of the posterior cranial fossa. In addition, introduction in the near future of functional MRI should lead to better knowledge of the relationship between cerebral lesions and functional zones. Ultrasonography remains a noninvasive and effective technique to seek lesions of the arteries supplying the brain. For spinal cord disorders, MRI is by far the examination of choice, except when contraindicated by the presence of cardiac pacemaker, metallic foreign bodies in the patient.