DUPLEX AND COLOR DOPPLER FLOW SONOGRAPHY OF OCCLUSION AND NEAR OCCLUSION OF THE CAROTID-ARTERY

PURPOSE: To determine whether color Doppler flow imaging with the use of slow-flow sensitivity improves sensitivity and specificity in the d ifferentiation of occlusion and near occlusion of the internal carotid artery. METHODS: Color Doppler and duplex sonography were performed i n symptomatic patients who had angiographically confirmed occlusion an d/or near occlusion of the internal carotid artery. The study consiste d of two phases: in the first, we assessed the usefulness of color Dop pler flow imaging by retrospectively reviewing the records of 35 patie nts with 36 angiographically confirmed occlusions or near occlusions o f the internal carotid artery who were examined with color Doppler flo w imaging at our institution during a period of 4 years; in the second phase, we incorporated color Doppler sonography into the routine scan ning protocols of 39 patients with 41 occluded or nearly occluded inte rnal carotid arteries seen over a period of 2 1/2 years. RESULTS: Over all, color Doppler imaging correctly showed all 34 of the near occlusi ons (sensitivity, 100%) and 36 of the 43 occlusions (specificity, 84%) . Seven patients with angiographically confirmed occlusion had sonogra phic findings that suggested near occlusion. In the first phase, eight near occlusions were misinterpreted as occlusions with conventional d uplex sonography, but were correctly shown with color Doppler flow ima ging. In the second phase, sensitivity increased from 50% to 100% (18 of 18) because of better detection of the nearly occluded lumen. This was at the expense of a decrease in specificity (from 100% to 78%), ow ing to identification of apparent flow in the internal carotid artery on color Doppler flow images in five of 23 occlusions. CONCLUSION: Bec ause of its ability to depict slow flow, color Doppler imaging with sl ow-flow sensitivity is superior to conventional duplex sonography for the noninvasive discrimination of occlusion from near occlusion of the internal carotid artery.