双向血流超声多普勒信号的小波降噪

利用小波框架结合软阈值的方法对表征双向血流的超声多普勒信号进行降噪。为了避免软阈值非线性处理对双向血流多普勒信号方向表征的影响,先对超声多普勒信号进行方向分离,然后对分离后的信号分别进行小波降噪,最后合成降噪后的双向血流超声多普勒信号。对计算机仿真的股动脉超声多普勒血流信号的降噪实验结果分析表明:本方法在不影响双向血流信息的前提下,提高了多普勒信号的信噪比、最大频率曲线和平均频率曲线的估计精度。仿真实验的结果证明了本方法可以用于双向血流超声多普勒信号的降噪。

Wavelet denoising for Doppler ultrasound signals from the bi-directional blood flow

A denoising method based on the soft-thresholding wavelet frames is proposed for Doppler ultrasound signals from the bi-directional blood flow. A direction separation step is firstly carried out to avoid the direction distortion of Doppler signals, which is induced from the non-linear soft-thresholding processing. Then a pair of separated signals are denoised independently. Finally Doppler signals from the bi-directional blood flow are reconstructed from the denoised separated signals. This approach has been applied to the simulated Doppler signals from femoral arteries. The experiment results show that the signal-to-noise-ratio (SNR) of denoised signals is enhanced without affecting the information of the bi-directional blood flow. The estimation precision of the maximum frequency and mean frequency are also improved. It is shown that this method is valid to denoise Doppler ultrasound signals from the bi-directional blood flow.