Non-contrast CT head:
Hyperdense distal basilar artery, signifying a thrombus.
No intracranial bleeding or evidence of acute infarction.
The cerebral sulci, ventricles, and basal cisterns are of normal width.
Bilateral widening of the frontoparietal extra-axial compartment is more prominent on the left.
Old lacunar infarct in the right corona radiata, and several tiny infarcts in the right external capsule. Tiny right periventricular infarct.
CTA head and neck:
15-mm-long filling defect in the distal basilar artery, occluding the origin of both PCAs.
Thin right vertebral artery, becoming even thinner distal to the PICA origin.
CT perfusion:
Wide area of reduced, sluggish, and preserved or elevated blood volume covers the bilateral PCA territory as well as the right SCA territory. The right thalamus is more extensively involved than the left one.