In vivo characterization and quantification of atherosclerotic carotid plaque components with multidetector computed tomography and histopathological correlation

Objective - In a previous in vitro study we have demonstrated that atherosclerotic plaque components can be characterized with multidetector computed tomography (MDCT) based on differences in Hounsfield values (HV). Now we evaluated the use of MDCT in vivo to characterize and quantify atherosclerotic carotid plaque components compared with histology as reference standard. Methods and Results - Fifteen symptomatic patients with carotid stenosis (> 70%) underwent MDCT angiography before carotid endarterectomy (CEA). From each CEA specimen 3 histological sections and corresponding MDCT images were selected. The HV of the major plaque components were assessed. The measured HV were: 657 +/- 416HU, 88 +/- 18HU, and 25 +/- 19HU for calcifications, fibrous tissue, and lipid core, respectively. The cut-off value to differentiate lipid core from fibrous tissue and fibrous tissue from calcifications was based on these measurements and set at 60 HU and 130 HU, respectively. Regression plots showed good correlations (R-2 > 0.73) between MDCT and histology except for lipid core areas, which had a good correlation (R-2 = 0.77) only in mildly calcified (0% to 10%) plaques. Conclusions - MDCT is able to quantify total plaque area, calcifications, and fibrous tissue in atherosclerotic carotid plaques in good correlation with histology. Lipid core can only be adequately quantified in mildly calcified plaques.