Preoperative cervical carotid artery contrast-enhanced ultrasound findings are associated with development of microembolic signals on transcranial Doppler during carotid exposure in endarterectomy

Background and aims Emboli from the surgical site during exposure of the carotid arteries cause new cerebral ischemic lesions or neurological deficits after carotid endarterectomy (CEA). The purpose of the present study was to determine whether preoperative contrast-enhanced ultrasound findings of the cervical carotid arteries are associated with the development of microembolic signals (MES) on transcranial Doppler, during exposure of the arteries in CEA, and to compare the predictive accuracy of contrast-enhanced ultrasound findings with that of gray-scale median (GSM). Methods Seventy patients with internal carotid artery stenosis (≥70%) underwent preoperative cervical carotid artery ultrasound and CEA under transcranial Doppler monitoring of MES in the ipsilateral middle cerebral artery. Maximally enhanced intensities on the intraplaque and lumen time-intensity curves, respectively, were obtained from contrast-enhanced ultrasonography data, and the ratio of the maximal intensity (EI p ) of the intraplaque curve to that (EI l ) of the lumen curve was calculated. The GSM value of the plaque was also measured. Results The area under the receiver operating characteristic curve to discriminate between the presence and absence of MES during exposure of the carotid arteries was significantly greater for EI p /EI l than for GSM ( p = 0.0108). Multivariate statistical analysis demonstrated that only EI p /EI l was significantly associated with the development of MES during exposure of the carotid arteries ( p = 0.0002). Conclusions Preoperative contrast-enhanced ultrasound findings of the cervical carotid arteries are associated with development of MES on transcranial Doppler during exposure of the arteries in CEA, and the predictive accuracy of contrast-enhanced ultrasound is greater than that of GSM.