Ischemic stroke - dense posterior cerebral artery (PCA) sign

Case contributed by Dr James Harvey


Presenting with new confusion, chest pain and visual changes.

Patient Data

Age: 70-80 years
Gender: Male

A linear density involves the left PCA. There is no area of hypodensity to indicate established infarct.

The patient was recalled for arterial phase imaging. CT perfusion was not available.

Arterial phase CT head


The left PCA is not seen. The vessel is occluded at its origin.
The right PCA has a foetal origin (a normal variant).
There is a relative paucity of collateral arterial vessels within the left PCA territory.

Case Discussion

A dense vessel on unenhanced CT is an insensitive but specific sign in acute ischemic stroke.
It is important to evaulate the thin slices for a dense vessel, as this finding may be missed on 3 mm slices.

Complete absence of the left P1 on arterial phase imaging indicates that the thrombus extends to its origin.

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