DWI is a sequence in MRI, which is magnetic resonance diffusion imaging.DWI allows early diagnosis of hyperacute cerebral infarction is cerebral infarction within two hours of onset. It can then show high signal changes on DWI, which is a bright lesion. The advantages of MRI, compared to CT, are that one is clear imaging and the other is that there is no radiation. The disadvantage is that it takes a longer time to do it. The other disadvantage is that the price is also higher than that of CT.