Duplex ultrasound velocity criteria for the stented carotid artery

Distribution of restenoses in 310 observations performed on patients with carotid artery stenting. Velocity threshold criteria developed for native unstented carotid arteries overestimates the number of patients with ≥20%, ≥50%, and ≥80% restenosis. Pie charts indicate number and percentage of observations in each category of stenosis. A, Distribution according to threshold criteria developed for native carotid arteries. B, True distribution of restenoses as confirmed by carotid angiography or computed tomography angiography.

Computed tomography (CT) angiography correlates with carotid angiography in the identification of carotid luminal stenosis in this linear regression analysis (solid line).

Scatterplot shows 310 pairs of ultrasound velocity measurements plotted against percentage of stenosis as determined by carotid angiography or computed tomography angiography. The solid line shows the linear regression analysis. Data-points were available across the entire spectrum of degrees of stenosis. A, Peak in-stent systolic velocity (PSV). B, In-stent carotid artery/common carotid artery ratio (ICA/CCA). C, End in-stent diastolic velocity (EDV).

Receiver operating characteristic (ROC) curve analysis was used to determine the accuracy of indicators of threshold velocities appropriate for the identification of (A) high-grade in-stent restenosis (ISR) ≥80%, (B) ISR ≥50%, and (C) residual stenosis ≥20%. ROC curves were developed for peak systolic velocity (PSV) (black line), internal carotid artery/common carotid artery ratios (red line), end diastolic velocity (EDV) (green line), and PSV/EDV ratios (blue line) for each threshold stenosis.