title: Research of fetal ECG extraction using wavelet analysis and adaptive filtering.
abstract: Extracting clean fetal electrocardiogram (ECG) signals is very important in fetal monitoring. In this paper, we proposed a new method for fetal ECG extraction based on wavelet analysis, the least mean square (LMS) adaptive filtering algorithm, and the spatially selective noise filtration (SSNF) algorithm. First, abdominal signals and thoracic signals were processed by stationary wavelet transform (SWT), and the wavelet coefficients at each scale were obtained. For each scale, the detail coefficients were processed by the LMS algorithm. The coefficient of the abdominal signal was taken as the original input of the LMS adaptive filtering system, and the coefficient of the thoracic signal as the reference input. Then, correlations of the processed wavelet coefficients were computed. The threshold was set and noise components were removed with the SSNF algorithm. Finally, the processed wavelet coefficients were reconstructed by inverse SWT to obtain fetal ECG. Twenty cases of simulated data and 12 cases of clinical data were used. Experimental results showed that the proposed method outperforms the LMS algorithm: (1) it shows improvement in case of superposition R-peaks of fetal ECG and maternal ECG; (2) noise disturbance is eliminated by incorporating the SSNF algorithm and the extracted waveform is more stable; and (3) the performance is proven quantitatively by SNR calculation. The results indicated that the proposed algorithm can be used for extracting fetal ECG from abdominal signals.
authors.affiliation: Biomedical Engineering Center, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China. Electronic address: wushuicai@bjut.edu.cn.
authors.forename: Shuicai
authors.initials: S
authors.lastname: Wu
authors.forename: Yanni
authors.initials: Y
authors.lastname: Shen
authors.forename: Zhuhuang
authors.initials: Z
authors.lastname: Zhou
authors.forename: Lan
authors.initials: L
authors.lastname: Lin
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zeng
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Gao
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D005333:Fetus / Q000502:physiology; D006801:Humans; D008955:Models, Cardiovascular; D011247:Pregnancy; D058067:Wavelet Analysis
keywords: Adaptive filtering; Fetal electrocardiogram; Least mean square; Stationary wavelet transform; Wavelet analysis