Acoustic analysis for evaluation of carotid artery stenosis via electronic stethoscope

• Main Authors: Jin-For Li, 李津佛
• Other Authors: Wei-Min Liu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/50739602609662267615

碩士 === 國立中正大學 === 資訊工程研究所 === 103 === Carotid stenosis is an important cause of ischemic stroke. Its severity is also correlated to the incidence of stroke. Such stenosis is defined as thickened arterial intima and thinning artery diameter. It causes turbulence of the blood flow. If we use stethoscope to listen this area, except the blood flow we will also hear extra noise called carotid bruit. Atherosclerosis is the main cause of stenosis. Since the development of atherosclerosis is quite slow, the patient can not immediately be aware of the change and does not have any symptom until severe stenosis. Attending annual screening and being examined by the health professionals with ultrasound imaging are the only way of detection. Currently there is no convenient and simple methods to help people monitor their carotid artery for any sign of stenosis. In the study we apply the electronic stethoscope on the neck and record the normal blood flow sound as well as the bruit. We develop a method to locate the systolic fragments from the audio recording, and calculate their approximate entropy and power ratio between low and high frequency. Through the process we try to identify any possible feature to determine carotid stenosis. After comparing the normal subject and patients clinically proven to have carotid stenosis, we found that the approximate entropy can be used as a preliminary indicator to determine whether carotid stenosis exists or not (P<0.01).