A study on the correlation between ultrasonic mechanical parameters of the long axis and histopathology of carotid artery plaques / 中华超声影像学杂志

ABSTRACT

Objective:To evaluate the mechanical parameters of the carotid artery plaques using velocity vector imaging(VVI), and to investigate the correlations between the mechanical parameters and the histological components in the plaques.Methods:Fifty-three patients undergoing carotid endarterectomy (CEA) from April to December, 2019 in Beijing Tiantan Hospital were selected and underwent VVI examination before operation. The plaques were divided into 5 parts along the long axis and named as R1, R2, R3, R4, R5, respectively. The mechanical parameters of the plaques in each region of interest were measured(longitudinal strain and strain rate). After operation, plaques were collected in 49 cases and the specimens were divided into five sections corresponding to preoperative images for HE staining and CD68 immunohistochemical analysis. According to the pathological diagnostic criteria of unstable plaques in previous studies, all plaques were divided into stable group and unstable group. Image-pro Plus 6.0 analysis software was used to measure the number of macrophages and the percentage of lipid core in plaques and the mean integral optical density of CD68 positive reaction area.Results:Among 49 cases, 33 cases were for unstable group, 16 cases were stable group. The longitudinal strain and strain rate of two groups of patients were R1>R2>R5>R4>R3, the number of macrophages, mean integral optical density, and percentage of lipid core were R2>R3>R1>R4>R5, differences were statistically significant ( P<0.05), the above indexes in unstable group were higher than in stable group, but there was no statistically significant difference ( P>0.05). The longitudinal strain was positively correlated with the number of macrophages, mean integral optical density and lipid core content in the plaque( r=0.300, 0.255, 0.394 respectively, P<0.05), and the strain rate was positively correlated with the number of macrophages and lipid core content in the plaque( r=0.199, 0.214 respectively, P<0.05) and r values in R1-R2 were higher than in R1-R5(longitudinal strain r=0.480, 0.418, 0.582; strain rate r=0.292, 0.319, P<0.05). Conclusions:The longitudinal strain and strain rate of the plaques are positively correlated with the macrophage and lipid core content of the plaques, and the r values of the upstream of plaques are higher. Therefore, VVI technique is valuable in detecting the stability of the plaques.