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

本研究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血栓溶解。评价超声能量强度与无创性和安全性的关系。还评价了微泡的使用是否对加速溶栓有增强作用。使用总共4种不同类型的PZT超声元件，1）1mm直径的圆柱形（Fujicera），1MHz驱动振动部分用特殊涂层隔离（最大电压为100Vpp）。2)6直径为2mm和8mm的圆盘型（2mm厚，2MHz）; 3）直径为20mm的圆盘型高强度超声探头。这些探头中的每一个都被插入到一个专门建造的装有脱气水的声学罐中。通过专门设计的高速电流检测器测量每个探针的功率输入并进行量化。利用微泡破裂可视化方法测量了超声压力，并进行了计算机分析。以占空比为10%、爆发频率为10Hz的脉冲群作为基线声学条件。钱德勒袢法人工血栓最快的是微泡（超声造影剂）利声显和Optison组合。直径为20 mm的元件产生最大的增强效果。

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.