Abstract: Objective To investigate the predictive value of carotid plaque vulnerability assessed by contrast-enhanced ultrasound combined with three-dimensional ultrasound in acute ischemic stroke(AIS). 
Methods A total of 261 outpatients or inpatients with carotid plaque thickness ≥2.0 mm detected after routine ultrasound examinations in our hospital were selected. According to the clinical diagnosis of AIS, all patients were divided into AIS group(n=126) and non-AIS group(n=135). Preferred carotid plaques were examined by contrast-enhanced ultrasound and three-dimensional ultrasound. The contrast-enhanced ultrasound quantitative parameter enhanced intensity(EI) and three-dimensional ultrasound quantitative parameters of carotid plaque thickness(PT), plaque volume(PV), percent area stenosis(PAS) and gray-scale median(GSM) were obtained. The above parameters were compared between two groups. The receiver operating characteristic(ROC) curve was used to analyze the predictive value of the parameters alone or in combination with statistical significance in AIS between two groups, and the cut-off value was determined. 
Results The EI value of carotid plaque in AIS group was higher than that in non-AIS group, and the GSM value was lower than that in non-AIS group(all P＜0.05); There was no significant difference in PT, PV and PAS of carotid plaque between two groups(all P＞0.05). Taking EI of 11.6 as cut-off value for predicting AIS, the area under curve was 0.730, and the sensitivity and specificity were 76.19% and 62.22%, respectively; Taking GSM of 33.5 as cut-off value for predicting AIS, the area under curve was 0.752, and the sensitivity and specificity were 78.57% and 62.22%, respectively; The area under curve of combined detection in predicting AIS was 0.840, and the sensitivity and specificity were 85.71% and 71.11%, respectively. 
Conclusion The combined detection of EI and GSM can accurately evaluate the vulnerability of carotid plaque and has a good predictive value for AIS.

Key words: stroke, carotid stenosis, ultrasonography