Equivalent density of calcium deposits – a new diagnostic pattern for atherocalcinosis

Abstract

Objective. To assess the density of the calcified substrate of atherosclerotic plaques of the carotid arteries using data from the computed tomography of patients with multifocal atherosclerosis. Material and methods. In 251 patients with verified atherosclerosis of the coronary and carotid arteries, with a high prevalence of angina pectoris, a history of myocardial infarction and modifiable cardiovascular risk factors, multislice computed tomography (MSCT) of the carotid arteries was performed to assess the calcium index and determine the equivalent density of calcium deposits (EDCD). A morphological sub-study of the material from the removed atherosclerotic plaques was carried out using scanning electron microscopy (SEM) in 12 patients. Results. According to the MSCT data, we identified 5 main types of calcium deposit location in the thickness of the atherosclerotic plaque. We noted that totally calcified plaques were associated with carotid artery stenosis by more than 30 %. According to the SEM data, we identified 2 leading patterns: diffuse and compact types of microcalcification. There was a statistically significant association of a low level of EDCD with a diffuse type of calcification both in vivo (p=0.010) and ex vivo (p=0.008). Patients, having carotid artery EDCD less than 0.21 mg/mm3, reported a significantly higher incidence of type 2 diabetes mellitus (p=0.0001) and a history of stroke (p=0.021). When comparing the MSCT data on the calcium deposit density and their localization in the atherosclerotic plaque, we noted a statistically significant predominance of low EDCD with superficial calcification of the plaque (p=0.002). Conclusion. The use of a calculated indicator of the equivalent density of calcium deposits of the atherosclerotic substrate allows us to non-invasively obtain new data on the structure of plaques. The observed association of the superficial distribution of calcification with low calcification density according to the MSCT data may indicate potential plaque instability.