Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1759709 | Ultrasonics | 2009 | 7 Pages |
Abstract
Denoising of Doppler signal is a preliminary and important step in medical ultrasound imaging. To denoise quadrature Doppler signal from bi-directional flow, we propose a novel method based on matching pursuit in this paper. The proposed method is an iterative decomposition algorithm which decomposes the original Doppler signal into a linear expansion of atoms in a time-frequency dictionary. The time-frequency dictionary is similar to Fourier transform domain and the atoms are similar to orthogonal bases in Fourier transform. In each step of the iteration, the atom which gives the largest inner product with the analyzed signal is selected from the dictionary, and the contribution of this atom is subtracted from the Doppler signal. This process is repeated on the residue until the SNR reaches the maximum. The linear expansion of the selected atoms is the denoised signal. Simulations were conducted on a simulation model with a sampling rate of 12.8Â kHz. When the original SNRs are 0Â dB, 2Â dB, 4Â dB, 6Â dB, 8Â dB, 10Â dB, the proposed method can improve the SNR for 7.9Â dB, 7.8Â dB, 7.5Â dB, 7.3Â dB, 7.05Â dB, 6.8Â dB respectively, reduce the root mean square error (RMSE) of the mean frequency waveform to 0.0441Â kHz, 0.0303Â kHz, 0.0245Â kHz, 0.0215Â kHz, 0.0161Â kHz, 0.0125Â kHz respectively, and suppress the RMSE of the spectral width waveform to 0.1774Â kHz, 0.0591Â kHz, 0.0486Â kHz, 0.0170Â kHz, 0.0145Â kHz, 0.0117Â kHz respectively. Preliminary in vivo evaluation was also carried out on a healthy 33-year-old male using B-K medical A/S 3535 ultrasound scanner, and the results showed that the proposed method can effectively enhance the Doppler spectrogram.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Acoustics and Ultrasonics
Authors
Yining Zheng,