In 141 consecutive patients with proximal MCA occlusion, 2 independent observers analyzed FLAIR images for the presence of FLAIR vascular hyperintensity-DWI mismatch before IV thrombolysis. PWI-DWI mismatch was defined as Volumehypoperfusion>1.8 × VolumeDWI, with Volumehypoperfusion>6 seconds on time to maximum value of the residue function maps in the 94 patients with available PWI