| Summary: | 碩士 === 國立成功大學 === 醫學工程研究所 === 87 === Atherosclerosis is one of the major disease entities causing significant mortality and mobility of human beings. This complications resulted from atherosclerosis such as hypertension, cerebral vascular diseases and coronary artery diseases are the major cause of deaths for adults. The physicians should try to realize the cause of atherosclerosis and how to observe the changes of blood wall resulted from atherosclerosis will be crucial for the earlier detection and earlier treatment. B-mode ultrasound has the advantage that it is noninvasive, can be used in nonsymptomatic subjects. Carotid artery is near the body surface and easily to be used for noninvasive ultrasound investigation the artery wall characteristics. Carotid artery wall thickness measured by ultrasound has recently been demonstrated to be significantly greater in patients with angiographycally defined coronary artery disease than in patients with normal coronary angiogram. Therefore, how to quantify the carotid artery wall changes becomes an important tool for atherosclerosis study. Currently, the clinicians use the longitudinal ultrasound image of carotid artery, then measure the intima-media thickness for the diagnosis reference of atherosclerotic lesions. However, the measurement results will depend on the interobserver variation. Actually, it is difficult to measure the intima-media thickness from the carotid ultrasound image when then the atherosclerotic lesions in early stage. To find a more sensitive way to quantify the atherosclerotic lesions is a good research topic. In this study, some image processing techniques are employed to investigate the artherosclerosis through the common carotid artery ultrasound image. The mean intima-media thickness, artery lumen diameter changes and the embolism rate are obtained from the locations of 10 mm before the bifurcation of common carotid artery. The results show that the mean intima-media thickness of 6 normal subjects are 0.45±0.05 mm and those of 12 patients with stroke are 0.79±0.14 mm . In general, the intima-media thickness of normal subjects are less than 0.6 mm, and those of the patients with stroke are greater than 0.6 mm. The intima-media thickness is a good parameter to differentiate the normal subjects from the patients with stoke. Finally, embolism rate is another parameter using to separate the normal group(13.25±1.77 %) and the patient group(22.38±4.26 %).
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