Thresholding-based Wavelet Packet Methods for Doppler Ultrasound Signal Denoising
Doppler ultrasound is widely used to diagnose vascular diseases because of its noninvasive advantages.Denoising of Doppler signals is necessary as a pre-processing for a high quality Doppler ultrasound system.Recently,there has been much work on denoising methods based on noise statistics and the spectrum distribution.Wavelet packet decomposing methods not only process low frequency components well,but also perform multi-level decomposition on high frequency contents,which is quite applicable in Doppler ultrasound signals because they have comparatively high frequency components dependent on flow velocity.This paper presents a threshold-based wavelet packet denoising method,which preserves useful high frequency components and offers higher signal–to-noise ratio (SNR) compared with straightforward waveletbased denoising methods.We then propose several algorithms to improve the selection of the threshold,and these methods are adaptive in the sense of coefficients obtained from different decomposed levels using the characteristics of the wavelet transform.In computer simulations,we have tested our algorithms and show improved SNR of simulated Doppler I/Q signals and better visualization of displayed Doppler spectrum.
Doppler signal wavelet packet analysis threshold shrinkage denoising
Jiangfeng Yu Dong C.Liu
School of Computer Science,Sichuan University,Chengdu,China
国际会议
7th Asian-Pacific Conference on Medical and Biological Engineering(第七届亚太地区生物工程学术会议)
北京
英文
2008-04-22（万方平台首次上网日期，不代表论文的发表时间）