Figure 10:73-year-old male presents 4 hours post-ictus with aphasia.
(A) NCCT demonstrates a hyperdense M2 segment of the left MCA (arrow).
(B) CT angiography reconstructed image confirms abrupt cut-off of this vessel, representing an embolus (arrow).
(C) MRI diffusion weighted images (DWI) show hyperintense signal abnormality involving the left insular cortex and frontal operculum, consistent with acute infarction.
(D) CT perfusion maps reveal a CT-CBV/CBF, MTT mismatched perfusion abnormality (arrows). There is decreased CBV in the left frontal lobe, with involvement of the insular and peri-insular region, corresponding to the infarcted region seen on DWI. The CT-CBV and DWI images are analogous in their representation of stroke “core” tissue that is irreversibly infarcted. However, the CT-CBF and MTT maps reveal a larger perfusion defect, representing “ischemic penumbra”, potentially at risk of infarction.