Purpose: To study the ability and accuracy of sonography to visualize carotid artery stents and assess criteria for carotid artery stent stenosis.
Methods: 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.
Results: 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.
Conclusions: 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.
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