[Diffusion-weighted imaging in acute stroke].

Diffusion-weighted imaging (DWI) enables the early detection of acute ischemic stroke and with high sensitivity and specificity. The signal changes are based on decreased diffusion of water molecules that is caused by cytotoxic edema. Despite the possibility of early detection of ischemic changes magnetic resonance imaging (MRI) is not normally necessary for the therapy decision; however, under some conditions, such as unknown time from onset of symptoms, multiparametric MRI including DWI can provide useful information that will influence the therapy.