高强度聚焦超声定位损伤离体牛肝的量效学研究

A Dose-Effect Study on High Intensity Focused Ultrasound Ablation of Bovine Liver Tissue in Vitro

目的 探讨不同频率、不同治疗剂量的高强度聚焦超声 (HIFU)定位损伤新鲜离体牛肝的量效关系。方法 采用治疗头频率分别为 5 .4MHz和 7.4MHz的高强度聚焦超声治疗系统在不同的治疗功率 40W和 5 0W时 ,分5s、8s、10s、15s、2 0s的治疗时间定位损伤新鲜离体牛肝 ,记录并测量靶区的温度和生物学焦域体积。结果 HIFU辐照5～ 8s可迅速提高靶区温度至 64～ 75℃ ,随着治疗时间增加 ,温度最高可达 85℃ ;在治疗头频率和输出功率相同时 ,随着辐照时间的延长 ,HIFU辐照部位的生物学焦域体积增大 ,同一部位辐照时间越长 ( 15～ 2 0s) ,生物学焦域中心越易产生炭化和空洞现象 ;在治疗头频率和辐照时间相同时 ,输出功率增大 ,生物学焦域体积增大 ;在输出功率和辐照时间相同时 ,频率为 7.4MHz的治疗头较频率为 5 .4MHz的治疗头所产生的生物学焦域体积大。结论 HIFU生物学焦域的形成与治疗头的工作频率、输出功率和治疗时间密切相关 ,在一定的参数条件下 ,生物学焦域可控制 。

Objective The purpose of this study was to evaluate the effect of different frequencies, different powers and different ablation time of high intensity focused ultrasound (HIFU) on bovine liver tissue in vitro. Methods Samples of bovine liver were irradiated by different frequencies, powers and irradiation time of HIFU. Volume and temperature of coagulative necrosis were recorded and compared. Results HIFU immediately increased the temperature of target areas to 64～75℃ within 5～8 seconds. The highest temperature could reach up to 85℃ afterwards. The biological focal region (BFR) enlarged and carbonization and cavitation emerged with increase in the irradiation time under a fixed HIFU power and frequency. BFR also extended relatively with more HIFU power and higher HIFU frequency under a fixed other two factors. Conclusions The formation of BFR had a close relationship with HIFU acoustic parameters such as frequency, power and irradiation time. BFR is controllable under these parameter, which was useful in clinical application of tumor ablation by HIFU.