Distribution of calcification in carotid endarterectomy tissues: Comparison of micro-computed tomography imaging with histology

Background: Calcification in atherosclerotic plaques has been viewed as a marker of plaque stability, but whether calcification accumulates in specific anatomic sites in the carotid artery is unknown. We determined the burden and distribution of calcified plaque in carotid endarterectomy (CEA) tissues.

Methods: A total of 22 CEA tissues were imaged with high-resolution micro-computed tomography (micro-CT). Total plaque burden and total calcium score using the Agatston method were quantified. The Agatston score (AS) was also normalized for tissue size. Plaque and calcium distribution were analyzed separately for three CEA regions: common segment (CS), bulb segment (BS), and internal/external segments (IES).

Results: The average CEA tissue length was 40.83 (interquartile range [IQR] 33.31-42.41) mm with total plaque burden of 103.45 (IQR: 78.84-156.81) mm3 and total AS of 38.58 (IQR 11.59-89.97). Total plaque volume was 21.02 (IQR: 14.47-25.42) mm3 in the CS, 37.89 (22.59-48.32) mm3 in the BS, and 54.05 (36.87-74.52) mm³ in the IES. Of the 22 tissues, 15 had no calcium in the CS compared with three in the bulb and two in the IES. Normalized calcified plaque was most prevalent in the BS, the IES and was least prevalent in the CS. The overall correlation of calcification between histology sections and matched micro-CT images was 0.86 (p<0.001).

Conclusions: Calcified plaque is heterogeneously distributed in CEA tissues with most in the bulb and IES regions. The amount of calcification in micro-CT slices shows a high correlation with matched histology sections.