高强度聚焦超声辐照离体及在体心肌组织的比较研究

目的　探讨并比较高强度聚焦超声(HIFU)定位损伤离体心肌及活体心肌的量效关系。方法　采用不同功率(3W ,4W ,5W)的HIFU ,在不同辐照时间(5S ,8S ,10S ,15S ,2 0S ,60S ,180S)的作用下,对5只正常猪离体心脏及8只活体兔心脏进行定位损伤,观察并测定损伤区形态及体积,并对损伤区进行病理学检查。结果　不同剂量下HIFU所致的生物学焦域范围为1～3 0 0mm3 ,不同处理因素间损伤体积具有显著性差异(P <0 .0 5 ) ,相同剂量下离体心肌受损体积大于在体心肌的受损体积。损伤形态随剂量增大由椭球形向锥体形、不规则形发展。组织学观察可见凝固性坏死及损伤区与正常心肌组织的明显分界。结论　HIFU可定点使离体心肌及活体心肌发生坏死而不伤及周围组织。

In vitro and in vivo experimental study of myocardial tussues exposed to high- intensity focused ultrasound irradiation

Objective The purpose of this study was to evaluate the impact of different power and ablation time of high-intensity focused ultrasound (HIFU) on myocardial tissues both in vitro and in vivo.Methods In vitro samples of pig myocardial tissue and in vivo hearts of New Zealand rabbits were exposed to HIFU at different powers (3W, 4W, 5W) and different exposure duration (5S, 8S,15S, 20S, 60S, 180S). The lesions were sized and the pathology were examined (immediately for in vitro experiment and 1 week later for in vivo experiment).Results The lesion volume varied greatly from 1-300 mm3 with the change of power and exposed duration, and significant differences were found among them. Under the exposure with same power and exposure time, the lesion of in vitro myocardium was bigger than that of in vivo myocardium.Remarkable pathologic changes were found at regional myocardium in microscopy. The shape of lesions appeared to be irregular with the increase of HIFU power and exposure time. Conclusion HIFU technology is able to ablate myocardium both in vitro and in vivo.