Quantitative Doppler ultrasound-based determination of volumetric blood flow

Conventional ultrasound Doppler velocity measurements are scaled by the cosine of the angle between the blood flow axis and ultrasound beam axis. In the approach used here, a transducer array was used to acquire a first cross-sectional Doppler data set of the vessel under examination. The transducer array was then moved to a different angle to acquire a second cross-sectional Doppler data set. Thereafter, we used the known angle between the two arrays ultrasound beams and the cosine (theta) scaled Doppler estimates to solve for the true angle between the blood flow axis and ultrasound beam axis of the first data set. Upon integrating the angle corrected velocity estimates over the entire vessel cross-section, we were able to estimate blood volume flow rate. The performance of the new approach was tested in a flow phantom that was designed to provide a constant flow in a simulated vessel. The data were collected for two sets of angles and three different flow velocities for each angle set. The unknown Doppler angle was calculated from the data and used to correct the flow velocity.