Role of sonography in the evaluation of carotid artery stents

Abstract

To study the ability and accuracy of sonography to visualize carotid artery stents and assess criteria for carotid artery stent stenosis. Duplex Doppler sonographic examinations were performed on 143 patients in whom 158 carotid artery stents were placed. Follow-up sonography to evaluate 24 of these stents within 24 h of stent placement was compared with post-procedure angiography. Another 23 stents were evaluated with sonography and with follow-up angiography more than 24 h after the procedure. The remainder of the 111 stents were evaluated exclusively with sonography after stent placement. Sonography was used to evaluate stent visibility, stent-media separation, and degree of stent stenosis. Wallstents were the best-visualized stents and Acculink the worst, but the differences were not statistically significant. Of 4 patients with stent-media separation >3 mm, 2 (50%) developed stenosis (40%-59%) at 6 and 12 months from stent placement. The other 2 stents with stent-media separation had not developed stenosis at 6 months' follow-up. A comparison of angiography and sonography performed on the date of stent placement revealed 19 true-negative sonography studies, 4 false-positive studies, 1 true-positive study, and no false-negative studies. A comparison of follow-up angiograms performed more than 24 h after the procedure with follow-up sonography revealed 17 true-negative studies, 1 false-positive study, 5 true-positive studies, and no false-negative studies. Sonography allows accurate evaluation of stent placement within the vessel and visualization of stent-media distance. Stent-media separation may be an early detection sign for stent stenosis development. Velocity criteria developed for non-stented vessels, when applied to stented vessels, correlate well with angiographic findings. Doppler velocity measurements when compared with visible stent assessment may reduce false-positives.