An Angle-Independent Cross-Sectional Doppler Method for Flow Estimation in the Common Carotid Artery

The Doppler ultrasound is the most common technique for noninvasive quantification of blood flow, which, in turn, is of major clinical importance for the assessment of the cardiovascular condition. In this article, a method is proposed in which the vessel is imaged in the short axis, which has the advantage of capturing the whole flow profile while measuring the vessel area simultaneously. This view is easier to obtain than the longitudinal image that is currently used in flow velocity estimation, reducing operator dependence. However, the Doppler angle in cross-sectional images is unknown since the vessel wall can no longer be used to estimate the flow direction. The proposed method to estimate the Doppler angle in these images is based on the elliptical intersection between a cylindrical vessel and the ultrasound plane. The parameters of this ellipse (major axis, minor axis, and rotation) are used to estimate the Doppler angle by solving a least-squares problem. Theoretical feasibility was shown in a geometrical model, after which the Doppler angle was estimated in simulated ultrasound images generated in Field II, yielding a mean error within 4°. In vitro, across 15 short-axis measurements with a wide variety of Doppler angles, errors in the flow estimates were below 10%, and in vivo, the average velocities in systole obtained from longitudinal ( v=69.1 cm/s) and cross-sectional ( v=66.5 cm/s) acquisitions were in agreement. Further research is required to validate these results on a larger population.