[Does diffusion and perfusion MRI modify the diagnosis and management of cerebral ischemic accidents?]

International audienceSince 25 years, CT has the capability to recognize hemorrhagic infarcts in emergency. On the other hand, cytotoxic oedema is visible only 12 or 24 hours after the onset of the ischemic stroke. T2 weighted MR-sequences are more sensitive and few hours after the onset, cytotoxic oedema appears as hypersignal, particularly using FLAIR sequences (Fluid Attenuated Inversion Recuperation). Described in 1986, diffusion-weighted MRI is a very sensitive technique to detect the cytotoxic oedema few minutes after the onset. The attenuation of the apparent diffusion coefficient must be evaluated with a map. This attenuation appears as hypersignal and its sensibility is close than 100%. The mismatch between data of perfusion MRI and diffusion MRI is the area of the ischemic penumbra. These new MRI techniques are easy to learn and must be available 24 h a day and 7 days a week in the stroke centers. They are simple, rapid and highly accurate for the diagnosis of acute ischemic stroke. They could be useful to select candidates to aggressive therapy during the first 3 or 6 hours. Potentially, they improve patient's outcome