脉冲高强度聚焦超声辐照离体组织所致组织摧毁术的实验研究

摘要

Objective To study the feasibility and mechanism of histotripsy in ex vivo bovine liver tissues exposed to pulsed high intensity focused ultrasound (pHIFU). Methods The bovine liver tissues were exposed to pHI-FU with 500 W acoustic power, 4 Hz pulse recurrence frequency (PRF), 1%-4% duty cycles for 60, 30, 20 and 15 s, irradiation depth was 20 mm. During these exposures, the temperatures in the focal region of pHIFU were measured by a thermocouple, and cavitation signals were detected with a passive cavitation detection (PCD) system. After the irradiations, the livers were sliced to obverse the damages. The specimens were hematoxylin-eosin (HE) stained. Results The visible damages in livers exposed to pHIFU with 1% - 3% duty cycles were holes. After HE staining, floe structure could be seen at the borders of erosions (holes) , the cells' structures were destroyed, the cytoplasms were homogeneous and the nucleuses were disappeared. Coagulation necrosis could be seen in the liver after 4% duty cycle pHIFU exposure. During the irradiations of pHIFU with duty cycles of 1%, 2%, 3% and 4%, the peak temperatures in the focal region were (41. 19±1. 42) ℃, (45.73 ± 1.92) ℃ , (53.07 ± 2.09) ℃ and (64. 13 ± 2. 56) ℃ respectively. Broadband noise could be seen in the frequency spectrums of cavitation signals. Conclusions Histotripsy can be induced in ex vivo bovine liver tissue exposed to pHIFU with high acoustic power and small duty cycles, cavitation involves.%目的 研究高声功率,低占空比的脉冲高强度聚焦超声(pulsed high intensity focused ultrasound,pHIFU)辐照离体牛肝组织所致组织摧毁术的可行性及机制.方法 使用500 W声功率、4 Hz脉冲重复频率、1％～4％占空比的pHIFU以20 mm深度辐照离体牛肝组织60、30、20 s和15 s.辐照中,使用热电偶和被动空化检测(passive cavitation detection,PCD)系统分别对焦域处的温度和空化信号进行检测.辐照结束后,切开牛肝,观察损伤形态,进行HE染色.结果 pHIFU辐照离体牛肝组织后均有损伤形成,占空比为1％～3％的pHIFU辐照后损伤为洞状；占空比为4％的pHIFU辐照后损伤为凝固性坏死.镜下观察,洞状损伤边缘处呈絮状结构,细胞结构完全破坏,胞浆均质状,细胞核消失.占空比为1％～4％的pHIFU辐照中焦域处的最高温度分别为(41.19±1.42)℃、(45.73±1.92)℃、(53.07±2.09)℃和(64.13±2.56)℃.PCD系统所测信号的频谱中均可见明显的宽带噪声.结论 高声功率,低占空比的pHIFU辐照离体牛肝组织可致组织摧毁术,且空化参与了组织摧毁术的实施.