Ultrasonic noninvasive measurement of elastic properties of arterial wall in atherosclerosis

1.动脉壁厚度的测量我们提出了三种对超声回波信号进行处理以获得动脉壁厚度的方法，并通过计算机模拟和离体实验验证了这些方法的准确性。当使用5 MHz的超声波时，通过回波频谱分析进行厚度测量的准确度优于5微米，最小可检测厚度约为0.3 mm。2.血管内超声换能器的研制了一种测量主动脉沿着局部弹性的血管内超声换能器。该传感器由PZT元件、用于定位该元件的柔性Ni-Ti丝和用于测量血压的导管组成，从而同时获得关于动脉的杨氏模量的四个参数，即，动脉直径、搏动直径变化、动脉壁厚度和脉压。在犬的体内实验中发现，主动脉的杨氏模量随着到外周的距离而逐渐增加。动脉弹性的临床测量对70例健康人、31例冠心病患者和36例高血压患者的腹主动脉进行了压力应变弹性模量的无创测量。在患者组中发现的弹性模量的显着增加显示了通过该技术早期检测动脉粥样硬化的希望。本项目的未来进展本项目的未来发展方向之一是将血管内超声换能器应用于动脉粥样硬化的准确检测，另一个是无创检测早期动脉粥样硬化的年龄相关性变化。

1. Measurement of arterial wall thicknessWe proposed three kinds of signal processings on an ultrasonic echo for obtaining arterial wall thickness to measure elastic properties of the artery using ultrasound.Accuracy of methods was examined by computer simlation and by in vitro experiments. The thickness measurement by spectral analysis of the echo attained the accuracy of better than 5 micron and minimum detectable thickness of about 0.3 mm, when ultrasound of 5 MHz was used.2. Development of intravascular ultrasonic transducerAn intravascular ultrasonic transducer for measuring regional elasticity along the aorta was developed. The transducer consists of PZT element, a flexible Ni-Ti wire for positioning the element and a catheter for blood pressure measurement, so as to obtain simultaneously four parameters concerning Young's modulus of the artery; i.e., diameter of the artery, pulsatile diameter change, artyerial wall thickness and pulse pressure. The progressive increase in Young's modulus of the aorta with distance to peripherals was found in in vivo experiments performed on dogs.3. Clinical measurement of arterial elasticityPressure strain elastic modulus of the abdominal aorta was noninvasively measured in 70 healthy subjects, 31 patients with coronary artery disease, and 36 patients with hypertension. Significant increase of the elastic modulus found in the patient groups shows promise of early detection of atherosclerosis by this technique.4. Future progress of this projectOne future development of this project is clinical application of the intravascular ultrasonic transducer for an accurate examination of atherosclerosis, and the other is nonivasive detection ofage-related atherosclerotic change of the artery at an early stage.