Contrast-enhanced ultrasonography for detecting histological carotid plaque rupture: Quantitative analysis of ulcer

Background Few studies have evaluated the distinct ability of contrast-enhanced ultrasonography for detecting carotid plaque rupture versus histological observations. Aims The aim of this study was to quantitatively assess the ability of contrast-enhanced ultrasonography to detect plaque rupture compared to ultrasonographic and histological images in terms of geometric accordance. Methods Carotid plaque morphology was classified as smooth, irregular, or ulcerated on 45 conventional ultrasonography and contrast-enhanced ultrasonography images from consecutive patients undergoing endarterectomy, and 55 regions of interests were captured on contrast-enhanced ultrasonography. A comparative study with a receiver operating characteristic analysis was performed using histological findings for reference. Results Contrast-enhanced ultrasonography exhibited a higher percentage of ulcerated findings in patients with plaque rupture compared to conventional ultrasonography (P=0.002) as well as an association with thrombus formation (P=0.048) and fibrous cap disruption (P<0.0001). On contrast-enhanced ultrasonography, ulcerated were significantly more likely than smooth findings when the fibrous cap was disrupted (odds ratio (OR), 41.5). The receiver operating characteristic areas under the curve for the orifice, depth, and width of the concavities on contrast-enhanced ultrasonography were significantly greater than 0.5, while their optimal cut-off values were 1.40mm, 1.30mm, and 1.88mm, respectively. When one of these variables was greater than the optimal cut-off value, the sensitivity, negative hit rate, and odds ratio for detecting fibrous cap disruption were 91.3%, 91.6%, and 23.1, respectively. Conclusions In our study, contrast-enhanced ultrasonography has high sensitivity for identifying histological plaque rupture, and the measurement of concavity on contrast-enhanced ultrasonography may enable the accurate detection of fibrous cap disruption.