Medically reviewed by Nicholas R. Metrus, MD The posterior communicating artery (PCOM) is a part of a group of arteries in the brain known as the circle of Willis. The artery connects the internal ...

(Left) Axial CT scan without contrast; (Right) Left internal carotid artery angiogram, Lateral oblique view. On the CT ... Aneurysms usually occur at arterial bifurcations and mostly arise from the ...

A CT scan of the head is ordered (Figure). Credit: Brady Pregerson, MD Making the Diagnosis. ... just posterior to the circle of Willis. Fortunately, this is not a bleed.

Watershed Infarction: Axial CT scan.Note the large hypodensity in the left basal ganglia and internal capsule. Although watershed infarcts are most often thought of as areas between two major blood ...