基于平移不变离散小波的多普勒血流信号杂波抑制

针对由血管壁和慢速运动组织产生的杂波会严重影响超声多普勒低速血流成分频谱估计的准确性问题，根据超声多普勒血流信号及杂波的特征，提出基于平移不变离散小波变换的抑制杂波方法，分别对仿真和实际超声颈动脉血流信号进行实验，并与高通滤波和离散小波变换方法进行比较，结果表明：经过平移不变离散小波变换方法抑制杂波后，信号的声谱图质量及性能指标均有明显改善，其中低速血流相对误差仅为4．86％，与高通滤波方法的相对误差10．28％和离散小波方法的相对误差7．26％相比，相对误差分别减小了5．42％和2．4％，低速血流成分频谱估计的准确性得到了提高。

Rejection of Clutter in Doppler Blood Flow Signals Based on Translation Invariant Discrete Wavelet Transform

The clutter originating from the vibrated vascular wall and slowly moving tissue influences seriously the accuracy of the frequency spectrum estimation of the ultrasound low blood flow signal.A method based on the translation invariant discrete wavelet transform(TIDWT) was proposed for clutter rejection according to the characteristics of the Doppler blood flow signal and clutter.Both simulated and in vivo Doppler carotid signals were tested.The results were compared with those of the high pass filter(HPF) and the discrete wavelet transform(DWT).The experiments show that the improvement including the spectrogram and performance parameters obtained by TIDWT over the other methods was notable,the relative error of low velocity blood signal was only 4.86%,and reduced by 5.42% and 2.4% compared with 10.28% of HPF and 7.26% of DWT respectively,thus the low velocity blood estimation accuracy is improved obviously.