Acute stroke patient with a clear DWI-PWI mismatch pattern in the right MCA territory. (Top row) Diffusion-weighted images (b = 1000 second mm2) showing the T2-weighted (b = 0) image, isotropic DWI (isoDWI) and ADC (isoADC). The exponential ADC (expADC) is the ratio of the isoDWI to the T2, which may be used to distinguish acute from subacute stroke as it eliminates “T2-shine through” effects. (Bottom row) CBV, CBF, Tmax, and MTT maps. The area of perfusion deficit is clearly apparent in the Tmax and MTT images. Although present, the ischemic area is less apparent on the CBF and CBV maps. DWI, diffusion-weighted imaging; PWI, perfusion-weighted imaging; MCA, middle cerebral artery; ADC, apparent diffusion coefficient; CBV, cerebral blood volume; CBF, cerebral blood flow; Tmax, time to peak of the residue function; MTT, mean transit time.