音響法による脳血管異常および人工弁機能の高分解能診断システム開発の研究
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概要
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For early diagnosis of diseases, resolution improvement of bio-acoustic signal analyzing system was studied. A system for detecting cerebral vessel blood flow noise (Bruit) was developed to diagnose cerebrovascular diseases such as cerebral aneurysm and stenosis in their early stage. The system could detect Bruit with the minimum SNR of 10 dB by adopting a newly developed acoustic transducer and signal-to-noise ratio (SNR) improvements over the whole system. It was shown that Wigner distribution has the noise reduction effect, and by applying it in conjunction with the FFT to the Bruit analysis, effective diagnosis information was obtained. A system for diagnosing prosthetic cardiac valve function by analyzing its closure sounds (clicks) was also developed. Features of the audible clicks were clarified precisely as a result of improving the time resolution by the Wigner distribution. Especially, maximum instantaneous frequency of Wigner distribution was found to be the candidate for quantitative diagnostic index of the thrombosed valve. Existence of new clicks in the ultrasonic range (ultrasonic clicks) was also found clinically, and the features of them were clarified. In addition, an in vitro test equipment based on the new structure was developed, and the source of the ultrasonic clicks was specified. By analyzing features of both clicks in audible range and ultrasonic range, the system could diagnose the valve dysfunction variously.
- 拓殖大学の論文
- 2004-01-25
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