Adaptive multi-lag for synthetic aperture vector flow imaging

The range of detectable velocities in ultrasound flow imaging is linked to the user selection of pulse repetition frequency. Whenever a region with large differences in velocity magnitude is visualized, a trade-off has to be made. This work suggests an adaptive spatio-temporaly independent, multi-lag method, which is performed in synthetic aperture vector flow data. Measurements are made on laminar and pulsatile, transverse flow profiles. A 7 MHz linear array is connected to the SARUS research, and acquisitions are made on a vessel phantom with recirculating blood mimicking fluid driven by a software controlled pump. A multi-lag velocity estimation is performed, and a lag is adaptively selected for every estimation point. Results from the constant flow compared to a true parabolic profile show an improvement in relative bias from 76.99% to 0.91% and standard deviation from 13.60% to 1.83% for the low velocity flow of 0.04 m/s; and relative bias from -2.23% to -1.87% and standard deviation from 3.71% to 2.29% for the high velocity flow of 0.4 m/s.