Development of a new ultrasound system for stroke and cardiac infarction therapy

本研究项目的目的是开发一种可插入血管内的微型陶瓷超声元件尖端导管装置。该装置可用于溶解凝块或加速溶栓。以超声能量强度为指标评价其无创性和安全性。同时对微泡的使用是否对加速溶栓有促进作用进行了评价。共使用4种不同类型的PZT超声元件，1)直径1 mm圆柱形(Fujicera)，1 MHz驱动振动部分用特殊涂层隔离(最大电压为100VPP)。2)6 mm和8 mm圆盘型(厚度2 mm，2 MHz)，3)直径20 mm圆盘型高强度超声探头。每个探头都被插入到一个专门建造的带有脱气水的声波水箱中。每个探头的输入功率由专门设计的高速电流检测器测量并量化。用一种新的微气泡崩塌可视化方法测量超声压力，并用计算机进行分析。以占空比为10%，脉冲串频率为10 Hz作为基线声学条件。Chandler Loop法人工血栓以微泡(超声造影剂)、Levovist和Optison联合应用效果最好。直径为20 mm的元件增强效果最好。

The object of this research project is to develop a miniature ceramic ultrasound element tipped catheter device which can be inserted inside a blood vessel. This device can be used to dissolve clot or accelerate thrombolysis. The non-invasiveness and safety was evaluated in correlation with intensity of ultrasound energy. The use of microbubble was also evaluated if there was an enhancing effect on the acceleration of thrombolysis. A total of 4 different types of PZT ultrasound elements were used, 1)1mm diameter cylinder shaped(Fujicera), 1MHz drive vibrating portion was isolated with a special coating, (maximum electrical voltage was 100 Vpp). 2)6 mm and 8 mm diameter disk type (2mm thickness, 2MHz), 3)20 mm diameter disk type high intensity ultrasound probe. Each of these probes were inserted into a specially built acoustic tank with degassed water. The power input into each probe was measured by a specifically designed high speed current detector and quantified. The ultrasound pressure was measured by a newly developed microbubble collapse visualization method and analyzed with computer. The duty ratio of 10%, burst rate of 10Hz was produce as baseline acoustic condition. Chandler Loop Method artificial thrombus was most accelerated by microbubbles (ultrasound contrast agent) Levovist and Optison combination. The 20 mm diameter element produce the most enhancing effect.