中文摘要：

目的观察连续高强度聚焦超声（CHIFU）与脉冲高强度聚焦超声（PHIFU）辐照离体牛晶状体所致凝固性坏死的变化过程,分析占空比对高强度聚焦超声（HIFU）辐照结果的影响。方法将80个离体牛晶状体分为4组行HIFU辐照,声功率均为500W,脉冲重复频率均为4Hz,A组（CHIFU组）,占空比100%,辐照时间1s;B组,占空比50%,辐照时间2s;C组,占空比20%,辐照时间5s;D组,占空比10%,辐照时间10s。以高速摄影设备和被动空化采集（PCD）系统记录凝固性坏死的发生过程和焦域处发出的声散射信息,测算各组凝固性坏死体积,并对空化行为进行分析。结果 A组（CHIFU组）凝固性坏死出现的平均时间为0.41s,B、C、D组分别为0.93、2.22、6.28s;CHIFU辐照凝固性坏死出现时间早于PHIFU辐照。各组辐照后形成的凝固性坏死形态有所不同。A组（CHIFU组）凝固性坏死体积随辐照时间呈线性增长,B、C、D组凝固性坏死体积均呈非线性增长。辐照结束后,A组（CHIFU组）凝固性坏死体积为（12.99±2.11）mm3,B组为（12.69±1.79）mm3,C组为（12.09±1.93）mm3,D组为（6.94±1.54）mm3。D组凝固性坏死体积均小于其余3组（P均〈0.05）,A、B、C组间两两比较差异无统计学意义（P均〉0.05）。各组均有空化发生,A组（CHIFU组）幅度均方根值（RMS）曲线有突然增大的过程,B、C、D组RMS曲线呈周期性的变化,占空比越高,空化行为越剧烈。结论CHIFU与PHIFU辐照所致牛晶状体凝固性坏死发生发展过程不同,调节HIFU辐照的占空比可影响凝固性坏死出现的时间及体积。

英文摘要：

Objective To observe the coagulation necrosis process of cattle crystalline len caused by continuous high in- tensity focused ultrasound （CHIFU） and pulsed high intensity focused ultrasound （PHIFU）, in order to study the effect of duty cycle to the results of high intensity focused ultrasound （HIFU）. Methods Eighty cattle crystalline lens were divided into 4 groups randomly with twenty lens in each group. HIFU was performed with acoustic power as 500 W and the pulse repetition frequency as 4 Hz. The duty cycle and exposure time were 100% and 1 s in group A （CHIFU group）, 500//oo and 2 s in group B, 20% and 5 s in group C, 10% and 10 s in group D, respectively. The change process of coagulation necro- sis was recorded using high speed imaging system, and the volume of coagulation necrosis at different times were measured and calculated. Acoustic scattering information was recorded by passive cavitation detection （PCD） system, and the cavita- tion information was analysed. Results The average time of appearing coagulative necrosis were 0. 41, 0. 93, 2.22 and 6.28 s in group A, B, C and D, respectively. The coagulation necrosis was appeared earlier by CHIFU （group A） than PHIFU （group B, C and D）. Various shapes of coagulative necrosis were found in different groups. The volume of coagu- lation necrosis was increased linearly with irradiation time in group A （CHIFU group）, and the volume of coagulative nec- rosis showed a nonlinear increase in group B, C and D. After the irradiation, the volume of coagulation necrosis was sepa- rately （12.99±2.11）mm3 in group A, （12.69±1.79）mm3 in group B, （12.09±1.93）mm3 in group C and （6.94± 1.54）mm3 in group D. The coagulation necrosis volume of group A, B and C were larger than that of group D （all P〈 0.05）. And no statistical differences of coagulation necrosis volume was found among A, B and C groups （all P〉0.05）. The cavitation occurred in all groups. Respectively in group A, remarkable rise was found in root-mea