COMBINED USE OF DUPLEX IMAGING AND MAGNETIC-RESONANCE ANGIOGRAPHY FOREVALUATION OF PATIENTS WITH SYMPTOMATIC IPSILATERAL HIGH-GRADE CAROTID STENOSIS

Purpose: Advances in cerebral vascular imaging suggest that patients w ith critical levels of carotid artery stenosis ( > 70%) who have sympt oms can be identified accurately and necessary information about the i ntracranial and extracranial circulation obtained before surgery witho ut conventional angiography. We have used carotid duplex imaging in co mbination with magnetic resonance angiography (MRA) to evaluate 20 pat ients with symptomatic ipsilateral high-grade carotid stenosis. Method s: All patients underwent CT and magnetic resonance imaging brain scan s, as well as MRA and conventional arteriography of the cerebral circu lation. Magnetic resonance angiograms were obtained with two-dimension al phase contrast and time-of-flight techniques. Phase contrast was us ed for intracranial vascular imaging and for determining qualitative f low velocities and the direction of blood flow in the circle of Willis . Two-dimensional time of flight was used to assess the carotid bifurc ations. Results. Twenty patients with symptoms (six with strokes, 11 w ith transient ischemic attacks, and three with amaurosis fugax) had du plex evidence of high-grade carotid stenoses. Computed tomographic and magnetic resonance brain scans were positive for cerebral infarction in six patients with clinical strokes. Comparison of MRA with conventi onal angiography was 91% accurate for high-grade stenoses and occlusio ns (sensitivity 100% and specificity 90% for stenosis; sensitivity/spe cificity was 100% for complete occlusion). Comparison of duplex imagin g with conventional angiography demonstrated 86% accuracy for detectio n of severe stenosis or occlusion (sensitivity 94% and specificity 89% for stenosis; sensitivity and specificity were 100% for complete occl usion). Conclusions: This study suggests that combined use of MRA and duplex imaging is accurate for detection and evaluation of high-grade carotid stenoses in patients with symptoms.