Real-time vector velocity profile measurement based on plane wave transmission

Standard Doppler ultrasound investigations are limited to detect the axial blood velocity component, as they cannot directly estimate the flow direction. A typical approach for obtaining a 2D velocity vector consists in combining the echoes received from two PW lines investigating the region of interest from different angles. The estimate is usually limited to the sample volume (SV) where the focused lines intersect. To get a complete picture of flow distribution, at least the entire velocity profile across a vessel must be reconstructed. In this work, we propose exploiting the plane waves originated from two different sub-arrays of a linear probe, to estimate the vector velocities in 512 SVs aligned to cover the diameter of large vessels. The method was tested on a laminar flow in a 8 mm diameter pipe. The probe was placed longitudinally over the pipe and the angle, α, between the probe surface and the pipe axis, was changed in the range 0°~20°. In particular, at α = 12°, the flow was perpendicular to one of the plane waves. The direction measurements featured a gain accuracy of 0.89 and a standard deviation (SD) <; 1.8°, while the velocity magnitude featured an average 2.8% overestimation with a coefficient of variation less than 1%.