Jing Bowen, Carrasco Dario I, AuYong Nicholas, Lindsey Brooks D
IEEE Trans Ultrason Ferroelectr Freq Control. 2023 Dec;70(12):1749-1760. doi: 10.1109/TUFFC.2023.3316748. Epub 2023 Dec 14.
A novel transverse velocity spectral estimation method is proposed to estimate the velocity component in the direction transverse to the beam axis for ultrafast imaging. The transverse oscillation was introduced by filtering the envelope data after the axial oscillation was removed. The complex transverse oscillated signal was then used to estimate the transverse velocity spectrum and mean velocity. In simulations, both steady flow with a parabolic flow profile and temporally varying flow were simulated to investigate the performance of the proposed method. Next, the proposed approach was used to estimate the flow velocity in a phantom with pulsatile flow, and finally, this method was applied in vivo in a small animal model. Results of the simulation study indicate that the proposed method provided an accurate velocity spectrogram for beam-to-flow angles from 45° to 90°, without significant performance degradation as the angle decreased. For the simulation of temporally varying flow, the proposed method had a reduced bias ( % versus 73.3%) and higher peak-to-background ratio (PBR) (>15.6 versus 10.5 dB) compared to previous methods. Results in a vessel phantom show that the temporally varying flow velocity can be estimated in the transverse direction obtained using the spectrogram produced by the proposed method operating on the envelope data. Finally, the proposed method was used to map the microvascular blood flow velocity in the mouse spinal cord, demonstrating the estimation of pulsatile blood flow in both the axial and transverse directions in vivo over several cardiac cycles.
提出了一种新颖的横向速度谱估计方法，用于在超快成像中估计与光束轴垂直方向上的速度分量。通过在去除轴向振荡后对包络数据进行滤波来引入横向振荡。然后使用复横向振荡信号来估计横向速度谱和平均速度。在模拟中，模拟了具有抛物线流型的稳定流和随时间变化的流，以研究所提出方法的性能。接下来，将所提出的方法用于估计具有脉动流的体模中的流速，最后，将该方法应用于小动物模型的体内实验。模拟研究结果表明，所提出的方法对于45°至90°的光束与流的角度提供了准确的速度谱图，并且随着角度减小性能没有显著下降。对于随时间变化的流的模拟，与先前方法相比，所提出的方法具有更小的偏差（分别为%和73.3%）和更高的峰背景比（PBR）（>15.6 dB对10.5 dB）。血管体模中的结果表明，可以在所提出的方法对包络数据进行处理产生的谱图所获得的横向方向上估计随时间变化的流速。最后，所提出的方法用于绘制小鼠脊髓中的微血管血流速度图，证明了在多个心动周期内在体内轴向和横向方向上对脉动血流的估计。
