Specific Imaging Findings

Wall calcifications are most commonly seen on unenhanced CT along the internal carotid arteries (carotid siphon), the vertebral arteries, middle cerebral arteries, and basilar artery. They range from fine and barely perceptible to chunky ones, several millimeters in thickness. When viewed in cross-section, mural calcifications appear ring-like, curvilinear, or stippled; when the affected artery is viewed longitudinally, they appear tubular, stippled and discontinuous, or plaque-like. Associated luminal narrowing may or may not be present. They are difficult to see on routine MRI, but very thick ones appear as a hypointense vessel rim.

Pertinent Clinical Information

Intracranial arterial calcifications are extremely common and often incidental on head CT, but are exceedingly uncommon under the age of 20. Their prevalence is roughly 50% at 41–60 and 90% at 61–80 years of age. In younger patients they may indicate an underlying metabolic disorder.

Differential Diagnosis

Calcified Aneurysms (144, 192)

1. • affected segment is dilated

2. • confirmed with CTA or MRA

3. • atherosclerotic calcifications can be mistaken for small aneurysms on CTA but distinguished with unenhanced CT

Dense Vessel Sign in Early Infarction (111)

1. • the vessel is mildly hyperdense, not calcified

2. • may coexist

Calcified Vascular Malformations (182, 183, 193)

1. • patchy calcifications common in cavernomas and AVMs

2. • typically peripherally located