長谷川 英之¹, 金井 浩¹, 中鉢 憲賢¹, 小岩 喜郎²

Hideyuki HASEGAWA¹, Hiroshi KANAI¹, Noriyoshi CHUBACHI¹, Yoshiro KOIWA²

¹東北大学大学院工学研究科電気・通信工学専攻, ²東北大学第1内科

¹Department of Electrical Engineering, Tohoku University Graduate School of Engineering, ²First Department of Internal Medicine, Tohoku University School of Medicine

キーワード : Atherosclerosis, Change in thickness of arterial wall, Elastic modulus, Small vibration on arterial wall, Acoustic characteristics

Diagnosis of early-stage atherosclerosis requires increase in spatial resolution to several millimeters, corresponding to the size of the macular lesions on the surface of the wall, when making a local evaluation of the acoustic characteristics of the arterial wall. Pulse wave velocity (PWV) ultrasound has been proposed for this purpose. The relation between PWV and Young's modulus in the circumferential direction of the arterial wall makes the noninvasive evaluation of the elastic characteristics of the arterial wall possible. Previously proposed methods do not provide sufficient spatial resolution. Here pulsive ultrasound is used to measure small vibration at the intima and the adventitia of the arterial wall from the surface of the skin accurately. Change in thickness of the arterial wall is obtained by integrating the difference between the two vibration signals at the intima and adventitia. The elastic modulus of the artrial wall is obtained by dividing the difference between systolic and diastolic blood pressure by the resultant change in thickness of the arterial wall, which is normalized by its thickness at diastole. Moreover, the proposed method is applied to evaluation of the elastic modulus of the human carotid artery in vivo.