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.