Peak Systolic Velocity Measured by Continuous-Wave Doppler Ultrasonography without Angle Correction in Patients with Internal Carotid Artery Stenosis

Abstract

Peak systolic velocity (PSV) is measured with pulse-wave (PW) Doppler with angle correction in patients with internal carotid artery stenosis (ICAS). However, the correlation between conventional angiography and PSV shows considerable scattering. We hypothesized that measuring PSV without angle correction would lead to better inter-rater reliability. This hypothesis was tested using a sector probe and continuous-wave (CW) Doppler without angle correction. Consecutive patients with more than 50% ICAS were enrolled from a prospective database. PSV was measured with PW Doppler with angle correction (PW PSV) and CW Doppler without angle correction (CW PSV) by 2 examiners. The inter-rater reliabilities of PW PSV and CW PSV were analyzed by Spearman's rank correlation test. A total of 37 ICAS sites (median 67 [interquartile range 57-78] % stenosis) were enrolled. Measuring PSV using a sector probe insonating nearly parallel to the flow was feasible in all cases. Inter-rater reproducibility of CW PSV (Spearman's ρ = .810) was similar to that of PW PSV (Spearman's ρ = .796). When limited to patients with a PSV greater than 200 cm/s with both PW Doppler examinations (25 ICAS sites), inter-rater reliability was relatively higher for CW PSV (Spearman's ρ = .674) than for PW PSV (Spearman's ρ = .423). Measuring PSV with CW Doppler using a sector probe was feasible. Inter-rater reliability was similar between PW Doppler with angle correction and CW Doppler without angle correction in evaluating PSV in patients with ICAS. CW Doppler appears to have better inter-rater reproducibility than PW Doppler in assessing high PSV.