Ability to use duplex US to quantify internal carotid arterial stenoses: Fact or fiction?

PURPOSE: To determine if duplex ultrasonography (US) can help predict the d egree of internal carotid arterial (ICA) stenosis. MATERIALS AND METHODS: ICA peak systolic velocity (PSV) and the:ratio Of th e PSV in the ICA to that in the ipsilateral common carotid artery (VICA/VCC A) were compared with the degree of arteriographically measured stenosis. I CAs were arteriographically subgrouped at 10% incremental levels' of stenos is and broader ranges. Mean PSV, VICA/VCCA, and SDs were calculated for eac h category Histograms showing the numbers of-stenotic ICAs in subgroups and for vessels with stenoses of greater than or equal to or less than 70% nar rowing were:constructed. The number of vessels correctly subgrouped with ty pical Doppler US thresholds was calculated. RESULTS: Mean PSV and VICA/VCCA increased with stenosis level (P < .01); SD s were wide. Histograms showed Doppler US values in the central groups acro ss all disease levels. Histograms differentiating at least or less than 70% stenosis showed minimal overlap. PSV and VICA/VCCA helped classify respect ively, 185 and 181 of 204 vessels with stenoses of less than 50%, 15 and 21 of 46 vessels with stenoses of 50%-69%, and 73 and 67 of 84 vessels with s tenoses of 70% or greater. When classifying stenoses as 69% or less or 70% or more, PSV and VICA/VCCA were correct in 90.6% and 90.3% of vessels. CONCLUSION: Doppler US is excellent for classifying stenoses as above or be low a single deg ree of severity but does not function well in stenosis sub classification.