Real-Time Vector Velocity Assessment Through Multigate Doppler and Plane Waves

Several ultrasound (US) methods have been recently proposed to produce 2D velocity vector fields with high temporal and spatial resolution. However, the real-time implementation in US scanners is heavily hampered by the high calculation power which is needed. In this work, we report a real-time vector Doppler imaging method which has been integrated in the open research system ULA-OP. The proposed approach exploits the plane waves transmitted from two sub-arrays of a linear probe, to estimate the velocity vectors in 512 sample volumes aligned along the probe axis. The method has been tested for accuracy and reproducibility through simulations and in-vitro experiments. Simulations over a 0°-90° angle range of a 0.5 m/s peak parabolic flow have yielded 0.75° bias and 1.1° standard deviation for direction measurement, and 0.6 cm/s bias with 3.1% coefficient of variation for velocity assessment. In vitro tests have supported the simulation results. Preliminary measurements on the carotid artery of a volunteer have highlighted the real-time system capability of imaging complex flow configurations in an intuitive, easy and quick way, as shown in a sample accompanying movie. These features have allowed obtaining reproducible peak velocity measurements, as needed for quantitative investigations on patients.