4-D Vector Doppler Imaging Using Row-Column Addressed Array

Large aperture 4-D blood flow Doppler imaging with high temporal resolution remains an important challenge. Different from the conventional matrix-array strategy, we proposed a 4-D ultrasound vector Doppler (4D-UVD) imaging method using a $128+128$ row-column addressed (RCA) array and a 256-channel ultrasound platform. This method integrates ultrafast 2-D plane wave transmission sequence and least-squares multiangle Doppler velocity estimator. The accuracy of the proposed method was evaluated in both simulations and phantom experiments of parabolic flow. The simulated result shows that the root-mean-squared error (RMSE) of estimated velocity is less than 15%. In the phantom experiments, the relative mean bias $\overline {B}$ and the standard deviation (SD) $\overline {\sigma }$ of the velocity profiles are less than 7.9% and 6.9%, respectively, suggesting a high estimated precision. Furthermore, in vivo feasibility of the approach was demonstrated in the human carotid artery. The blood flow velocity of the carotid artery was continuously measured over seven cardiac cycles at a 1-kHz volume rate. The fluctuations of the estimated mean and peak velocities were highly consistent with the pulse waves measured using a gating pulse sensor, yielding synchronization coefficients of 0.85 and 0.87, respectively. It is thus concluded that the proposed method can achieve a large aperture 4-D vector flow imaging with high temporal resolution using an RCA probe.