動脈硬化定量評価のための機能的組織診断法の開発 : 高速度超音波断層法と連続圧計測による動脈血管弾性解析(1部生体の計測)

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The incidence of circulatory diseases caused by arteriosclerosis is increasing in Japan. Cerebrovascular and heart diseases account for about one-third of all fatalities in Japan, killing more people than cancer does. Nonetheless, there are currently no established methods to assess arteriosclerosis. Due to the recent development of high-resolution ultrasound echography, it has become possible to non-invasively diagnose arteriosclerosis. Even newly developed diagnostic methods, however, only examine the morphology of arteries, and since they cannot quantitatively assess arteriosclerosis, this disease can only be diagnosed when the morphology of arterial walls changes. By the time arterial walls have thickened or calcified, arteriosclerosis has already been established. Therefore, to prevent the onset of diseases caused by arteriosclerosis, we have to diagnose arteriosclerosis before the appearance of morphological changes and take appropriate measures. We thought that for a diagnostic method for arteriosclerosis to be truly useful in preventing diseases, the functional tissue characterization of vascular walls must be quantitatively assessed. Furthermore, from the viewpoint of preventive medicine, this diagnostic method should be noninvasive, suitable for integration into mass screening programs, and capable of assessing arteriosclerosis that is undetectable by exising ultrasound echography. We have studied the functional tissue characterization of the common carotid artery using a time series of ultrasound echography images. Shifts in the wall of the common carotid artery and their velocities were calculated from ultrasound echography images. Based on the blood pressure of the same artery, the motion of the wall of the common carotid artery was also analyzed. The blood pressure of the common carotid artery was non-invasively measured by tonometry using a continuous sphygmomanometer, and the pulse wave of the common carotid artery was determined by a carotid artery pulse wave sensor, taking into account the time gap between the common carotid artery and the radial artery. We have studied the functional tissue characterization of vascular walls in subjects that were 13 to 89 years old (mean: 57.4 years) with various health conditions (including 37 healthy individuals, 68 obese individuals, 76 hypertensive patients, 35 diabetic patients, 30 patients with hyperlipidemia, 14 patients with chronic renal failure, 12 patients with cerebral infarction, and 6 patients with old myocardial infarction). The results of clinical laboratory tests on these subjects were also recorded, and their relationships with the functional characteristics of the wall of the common carotid artery were statistically analyzed. Patients with cardiac arrhythmia were excluded from the present study. We found that the cross-sectional area of the common carotid artery and its expansion velocity are important parameters in a dynamic model of the common carotid artery. Next, we clarified that a nonlinear viscoelasticity was necessary in this type of analysis, and that the nonlinear viscoelastic parameters changed with age. By analyzing these parameters, we were able to detect functional arteriosclerosis. So far, we have found that elderly and hypertensive patients can be differentiated from the healthy individuals by analyzing the viscoelasticity of the arteries.
バイオメカニズム学会の論文
1998-11-25

動脈硬化定量評価のための機能的組織診断法の開発 : 高速度超音波断層法と連続圧計測による動脈血管弾性解析(1部生体の計測)

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動脈硬化定量評価のための機能的組織診断法の開発 : 高速度超音波断層法と連続圧計測による動脈血管弾性解析(1部 生体の計測)

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動脈硬化定量評価のための機能的組織診断法の開発 : 高速度超音波断層法と連続圧計測による動脈血管弾性解析(1部生体の計測)