Figure 3.

Example of a patient with collateral failure. At baseline, the distal right internal carotid artery is occluded but the digitally-subtracted perfusion magnetic resonance imaging data demonstrates excellent collateral flow via the circle of Willis (anterior communicating artery, images acquired every 2 seconds, selected frames shown). This corresponds to a large mismatch between the diffusion lesion and Tmax lesion volume with relatively mild Tmax severity and preserved cerebral blood volume (CBV). However, by day 4, there is no longer significant flow within these collateral vessels, accompanied by major infarct growth, increase in Tmax delay severity and reduction in cerebral blood volume.