Velocity vector estimation in synthetic aperture flow and B-mode imaging

A method for determining both velocity magnitude and angle in a synthetic aperture ultrasound system is described. The approach uses directional beamforming along the flow direction and cross-correlation to determine velocity magnitude. The angle of the flow is determined from the maximum normalized correlation calculated as a function of angle. The method is investigated using data measured by an experimental ultrasound scanner from a flow rig. A commercial 7 MHz linear array transducer is used and data are measured for flow angles of 60° and 90°. The velocity magnitude is determined with a precision of 0.36 % (60°) and 1.2 % (90°), respectively. The 60° angle is estimated with a bias of 0.54° and a standard deviation of 2.1°. For 90° the bias is 0.0003° and standard deviation 1.32°.