Typical appearances of an a relatively large and established MCA (middle cerebral artery) infarct with thrombus visualized in the proximal MCA (hyperdense MCA sign).

A subsequent CT (not uploaded) confirmed marked deterioration within 24 hours and a craniotomy was performed to facilitate decompression.

Large vessel occlusion from thrombus is atypical in this age group (45 year old female) and an underlying coagulopathy was suspected, but not found.