DUPLEX ULTRASONOGRAPHY CRITERIA FOR INTERNAL CAROTID STENOSIS OF MORETHAN 70-PERCENT DIAMETER - ANGIOGRAPHIC CORRELATION AND RECEIVER OPERATING CHARACTERISTIC CURVE ANALYSIS

OBJECTIVE: To determine duplex ultrasonography criteria for detecting stenosis of 70% or more in the internal carotid artery, to be used as a means of selecting candidates suitable for endarterectomy (a procedu re suggested by the North American Symptomatic Carotid Endarterectomy Trial as appropriate for symptomatic patients with 70% to 99% stenosis ). PATIENTS-AND METHODS: Between Jan. 1, 1991, and Apr. 30, 1993, 120 patients underwent internal carotid angiography at a tertiary care hos pital for transient ischemic attacks, asymptomatic bruits or preoperat ive assessment. Of these, 83 also underwent duplex ultrasonography wit hin 31 days of angiography. The angiographic and sonographic studies f or 145 vessels in 75 of the patients (50 men and 25 women) were suitab le for further study. The sonographic criteria were selected on the ba sis of a receiver operating characteristic curve relating peak systoli c velocity of the internal carotid artery to the degree of stenosis de termined angiographically. RESULTS: Angiography indicated that 33 of t he vessels had stenosis of 70% or more and that 12 additional vessels were completely occluded. The combined sonographic criteria of peak sy stolic velocity of less than 40 cm/s or 175 cm/s or more yielded 91% s ensitivity and 60% specificity for angiographically determined stenosi s of 70% or more. CONCLUSION: In this patient population the combined criteria of peak systolic velocity of less than 40 cm/s or 175 cm/s or more were highly sensitive and reasonably specific for internal carot id artery stenosis of 70% or more.