Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Feb 2007
[Investigation of morphology and anatomic variations of circle of Willis and measurement of diameter of cerebral arteries by 3D-TOF angiography].
To observe the morphology and anatomic variations of the circle of Willis and its clinical significance. To measure and establish the normal reference parameters of average diameters of its component vessels in the healthy Chinese by using 3D-TOF MR angiograms and to determine whether age-or sex-related differences exists in the circle' anatomy. MRA was performed in 153 healthy subjects. ⋯ The display rate of the anterior and the posterior communicating arteries was 87.58%o (134/153) and 65.34% (100/153) respectively. Display rate of fetaltype posterior cerebral artery(PCA) was 20.92%. 3D-TOF MR angiography has important clinical significance for evaluating morphology and anatomic variations of circle of Willis. The normal values of diameter of cerebral arteries on MR angiograms may play a reference role in diagnosing cerebral vascular diseases.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Dec 2006
[A quality controllable algorithm for ECG compression based on wavelet transform and ROI coding].
This paper presents an ECG compression algorithm based on wavelet transform and region of interest (ROI) coding. The algorithm has realized near-lossless coding in ROI and quality controllable lossy coding outside of ROI. After mean removal of the original signal, multi-layer orthogonal discrete wavelet transform is performed. ⋯ The map, which records the positions of the important coefficients in the original wavelet coefficients vector, is compressed with a run-length encoder. Huffman coding has been applied to improve the compression ratio. ECG signals taken from the MIT/BIH arrhythmia database are tested, and satisfactory results in terms of clinical information preserving, quality and compress ratio are obtained.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Dec 2006
Comparative Study[Comparison of heart rate variability in healthy young men during exposure to different altitudes].
The characteristics of cardiovascular autonomic nerve system(ANS) modulation during exposure to three different altitudes were compared by time domain, spectral and nonlinear analysis of short-(5 minutes)term heart rate variability (HRV). The standard deviation of all RR intervals (SDNN), the square root of the mean squared differences of successive RR intervals (rMSSD), the percentage of successive interval differences >50 ms (PNN50), low frequency (LF), high frequency power (HF), and total power (TP) at 2800 m were slightly higher than those at 1856 m, but the differences were non-significant statistically. ⋯ These results show that parasympathetic nerve activity decreases significantly, and ANS modulation is blunted after exposure to higher altitude. This kind of change of ANS may contribute to further elucidate pathophysiology in body after exposure to high altitude.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Oct 2006
[The application of adaptive algorithm and wavelet transform in the filtering of ECG signal].
Electrocardiographic (ECG) signal are a kind of basic physiological signals of human body, and are very important in clinical diagnosis. But the ECG signals from body surface are often interfered by noises such as 50 Hz noise, baseline displacemant, electromyography (EMG) noise and edv. ⋯ To eliminate the ECG signals noises mentioned above,this paper adopts LMS adaptive algorithm and wavelet transform theory to design three kinds of digital adaptive filters-adaptive noise cancellation filter, wavelet transform filter and adaptive signal dividing filter to filter the corresponding noises. The results show that the three kinds of noises existing in the ECG signal have been efficiently eliminated.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Oct 2006
[Dynamic analysis of heart rate variability based on wavelet transform].
The analysis of heart rate variability (HRV) has become a tool for noninvasively detecting the cardiovascular modulation of autonomic nervous system. Traditional analysis in frequency domain mainly includes calculating the power and detecting the peak frequency of each physiological frequency band. Whether employing the classical method or AR model to estimate the spectrum, the approximate stationarity of HRV is presupposed. ⋯ A dynamic analysis method based on wavelet transform was proposed in this paper, which not only can obtain the traditional indices in frequency domain, but can compute their dynamic values varying with time, called short-time power and short-time LF/HF ratio. The latter can dynamically evaluate the activity of autonomic nervous. Finally the method was applied to trace the balance of autonomic nervous in Atropin drag experiment.