Extent of intra-arterial calcification on head CT is predictive of the degree of intracranial atherosclerosis on digital subtraction angiography

Background: Intracranial intra-arterial calcifications (ICAC) are a common finding on head CT examinations, but their significance is not known. The aim of this study is to determine if a relationship exists between ICAC on head CT and the presence of a high-grade atherosclerotic stenosis on cerebral angiography. Methods: This was a retrospective study of 108 consecutive patients admitted to the stroke service at Parkland Hospital in Dallas, Tex., USA. Each patient had undergone a head CT and catheter-based angiographic study to meet the inclusion criteria. Demographic information was recorded along with CT imaging data in regards to the amount of calcification. Angiographic images were reviewed independently, and a comparison was made to determine if calcification was predictive of finding a high-grade stenosis on angiography. Results: A total of 108 consecutive patients with a mean age of 56 ± 12 years were studied. Of the 540 vessels studied, 65 (12%) were found to have a stenosis of ≥50% on angiography, and 71 (13.1%) were found to have a calcium grade of 3 or 4 on head CT. ICAC appeared to be more common in the anterior circulation compared to the posterior circulation. Patients with grade 3 or 4 calcification of an intracranial vessel on head CT were more likely to have a stenosis of ≥50% on cerebral angiography. Conclusions: The presence of ICAC on head CT appears to correlate with the presence of an underlying intracranial stenosis on angiography. Further study is required to validate these preliminary findings.