Is a Constant Doppler Angle of Insonation Worthwhile during Carotid Duplex Ultrasound?

Abstract

Background/Aims. —Velocity ratio is a good indication to determine the degree of vessel stenosis. This study was done to determine the effect of Doppler angle in carotid artery velocity ratio measurements. Methods. —Thirty-eight patients who underwent routine carotid duplex ultrasound were asked to participate in this study. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) at distal common carotid artery (CCA) and proximal internal carotid artery (ICA) with constant and different Doppler angles were recorded. The ICA/CCA PSV ratio was calculated. Results. —There were 12 female and 26 male patients; their mean age (year, ±SD) was 50.53 ± 16.4 and their mean body mass index (kg/m2, ±SD) was 29.6 ± 9.53. The mean ± SD. ICA PSV, CCA PSV, and the ICA/CCA PSV ratio with a 60° Doppler angle were 80.40 ± 16.6, 87.90 ± 16.96, and 0.93 ± 0.18, respectively. However, the mean ± SD. ICA PSV, CCA PSV, and the ICA/CCA PSV ratio with a 45° Doppler angle were 63.84 ± 16.18, 70.67 ± 16.19, and 0.91 ± 0.17, respectively. Moreover, the ICA60°/CCA45° PSV ratio was 1.17 ± 0.25 and the ICA45°/CCA60° PSV ratio was 0.73 ± 0.16. Paired Student's t-test showed a statistical significance for different Doppler angle of insonation ( p = 0.001) but was not statistically significant when the Doppler angle was constant ( p = 0.389). Conclusion. —Constant Doppler angle is preferred during carotid ultrasound for a consistent result.