Correlation between calcium, water contents and ultrasonographic appearance of atherosclerotic lesions of carotid artery lesions

BACKGROUND: We tested the hypothesis whether there is a correlation between the echogenicity and calcium and water contents of carotid plaques. PATIENTS AND METHODS: Ninety carotid befurcations from 45 deceased patients were removed during autopsy. Thirty-four plaques were categorized as homogenous echolucent (HEL), homogenous echogenic (HEG) and heterogenous (HE) plaques based on premortem B-mode image. Water content was expressed in % of wet weight. Ca was determined by proton-induced X-ray emission and expressed in ppm. Relative optical density of the B-mode images was analyzed offline using a computer program. HE plaques showed an intermediate calcium content (7,310 [4,840-9,920 ppm]) that was statistically not different from echolucent plaques. Water content of HEG plaques was statistically not different from HEL and HE (HEG:53.5 [35.5-64%], HEL: 73.5 [69.7-78.5%], HE: 70.6 [67.4-73.9%]). HEG plaques had the highest relative optical densities (196 [188-217%]). HEL and HE had similar relative optical densities (HEL: 176 [164-187%], HE: 164 [144-188%], respectively). A significant positive correlation was found between the Ca content and relative optical density of plaques. CONCLUSIONS: Echogenicity of carotid plaques increases along with their calcium content. Water content may be an important factor in differentiation of different plaques.