Plane-wave based vector flow imaging: Beamforming and velocity estimation loads in different processing scenarios

Recent advancements of ultrasound vector Doppler techniques have boosted the investigation of 2D regions of interest (ROIs). Several methods were proposed, but their implementation on commercial systems is still limited by technical difficulties. First, the investigation of wide ROIs at high frame rate requires the transmission of plane waves and parallel beamforming in reception. Furthermore, the extraction of vector velocities along multiple lines is typically performed by computationally demanding multi-beam or speckle tracking techniques. In this work, we compare, in terms of accuracy and computational load, the performance offered by these two techniques when the vector velocities are estimated for increasing numbers of lines. Experimental results obtained by using the ULA-OP 256 research system confirmed similar performance in terms of accuracy, with overall bias and standard deviation lower than 20%. The assessment of beamforming and computational loads demonstrates that the speckle tracking technique based on frequency-domain displacement evaluation is convenient when vector velocities over 8 or more lines are detected.