Fig 3.

Hyperacute infarction (2 hours after onset) in a 39-year-old man with the left internal carotid artery dissection presenting with right-sided weakness. (From Moritani T, Ekholm S, Westesson PL. Diffusion-Weighted MR Imaging of the Brain. Berlin: Springer-Verlag; 2004. Used with permission.)

A, Fluid-attenuated inversion recovery (FLAIR) image shows no apparent parenchymal abnormalities, but linear hyperintensities represent slow flow in the peripheral vessels (arrows). B and C, DW images show a mildly hyperintense lesion with decreased ADC in the left frontoparietal white matter; this represents cytotoxic edema extending into the ischemic penumbra, propagated by excitotoxic mechanisms (arrows).

D, Perfusion-weighted image shows prolonged mean time to peak in the entire left MCA and anterior cerebral artery territories.