Background and Purpose- Intracranial artery calcification detected by computed tomography is associated with ischemic stroke as an indicator of intracranial atherosclerosis. However, little is known about its histopathology. This study aimed to explore the intracranial calcification patterns and their associations with atherosclerotic plaques. Methods- We recruited 32 adult autopsy cases to assess the calcification patterns and distributions in the middle cerebral artery, vertebral artery, and basilar artery. The relationships of calcification patterns with plaque phenotype and luminal stenosis were evaluated. The calcification patterns on computed tomography were correlated with that on histology. Results- Visible calcifications were detected within 37 (39%) segments, including 25 segments with intimal calcification, 6 segments with internal elastic lamina calcification, 3 segments with adventitial calcification, and 3 segments with concurrent calcification. Calcification occurred more often in the vertebral artery (51%), followed by the middle cerebral artery (35%) and basilar artery (14%; P<0.01 for vertebral artery versus basilar artery). Internal elastic lamina calcification was predominantly detected in the vertebral artery (7/8, 88%). All of the 27 (100%) intimal calcifications were present in the progressive atherosclerotic lesions ( P<0.001), whereas only 3/8 (38%) internal elastic lamina calcifications and 4/6 (67%) adventitial calcifications were associated with progressive plaques. Arteries with intimal calcification had more severe luminal stenosis than those without (46% versus 21%; P<0.001). Conclusions- Our histological findings indicate that the presence of intracranial artery calcification has 3 patterns, including intimal, internal elastic lamina, and adventitial calcifications. But only intimal calcification is related with progressive atherosclerotic lesions, indicative of a proxy for intracranial atherosclerosis.
Keywords: atherosclerosis; basilar artery; calcification; middle cerebral artery; stroke; vertebral artery.