Diagnostic criteria for the determination of clinically significant internal carotid artery stenosis using duplex ultrasound

Background. Carotid endarterectomy is beneficial in symptomatic patients with >= 70% stenosis at the bifurcation of the internal carotid artery.The fact that the duplex ultrasound is widely used, inexpensive and non-invasive for examination of the carotid arteries underlines the importance of high accuracy of this method for grading internal artery stenosis. Patients and Methods. Duplex scans and arteriograms of carotid arteries of 142 patients were reviewed. Peak and end-diastolic velocities of the common and internal carotid arteries were recorded, and the percent stenosis of the internal carotid artery was determined by arteriogram. Receiver-operator characteristic curves of sensitivity, specificity, positive and negative predictive values and accuracy were determined. Results. The recommended criteria for the detection of >= 70% stenosis of the internal carotid artery were: peak systolic velocity in the internal carotid artery >= 215 cm/s, end-diastolic velocity in the internal carotid artery >= 65 cm/s, ratio of peak systolic velocities in the internal and common carotid arteries >= 2.7 and ratio of the end-diastolic velocities of the internal and common carotid arteries >= 3.7. Conclusion. These criteria allow for reliable determination of internal carotid artery stenosis >= 70% by duplex ultrasound.