IEEE Trans Ultrason Ferroelectr Freq Control. 2019 Jan;66(1):18-25. doi: 10.1109/TUFFC.2018.2876331. Epub 2018 Oct 16.
High-intensity focused ultrasound (HIFU) has emerged as an effective and noninvasive therapeutic modality for cancer and solid tumor. Despite its promising clinical outcomes and the approval of the Food and Drug Administration of many countries, the ablation time of a large target is long, so enhancement of the lesion production is highly desired. In this study, dual-frequency (or amplitude modulation) excitation was evaluated both numerically and experimentally, and its performance was compared with that using single-frequency excitation at the same power output. The nonlinear wave propagation model was used to simulate the acoustic field of HIFU exposure, the Gilmore model was used to determine the induced bubble dynamics, and then absorbed acoustic energy and bubble-enhanced heating were put into the BioHeat equation to calculate the temperature elevation. HIFU-produced lesion in the bovine serum albumin-embedded polyacrylamide was recorded photographically. It is found that dual-frequency excitation (3.16 + 3.20MHz) can increase the lesion area by 35%-65% compared to single-frequency excitation (3.18 MHz) at the same power output. The lesion enhancement increases with the pulse repetition frequency, duty cycle, and modulation depth and decreases with the frequency difference. In summary, dual-frequency excitation can increase the bubble cavitation and the associated heating for HIFU ablation for large lesion production.
高强度聚焦超声（HIFU）已成为癌症和实体肿瘤的一种有效且非侵入性的治疗方式。尽管其具有有前景的临床结果，并且许多国家的食品和药物管理局都已批准，但对于大目标的消融时间仍然很长，因此非常需要增强病变的产生。在这项研究中，我们从数值和实验两方面评估了双频（或幅度调制）激发，并将其性能与相同功率输出下使用单频激发进行了比较。非线性波传播模型用于模拟 HIFU 暴露的声场，吉尔摩模型用于确定诱导气泡动力学，然后将吸收声能和气泡增强加热纳入生物热方程以计算温度升高。记录了牛血清白蛋白嵌入聚丙烯酰胺中的 HIFU 产生的病变。结果发现，与相同功率输出下的单频激发（3.18 MHz）相比，双频激发（3.16 + 3.20 MHz）可将病变面积增加 35％-65％。病变增强随脉冲重复频率、占空比和调制深度的增加而增加，随频率差的增大而减小。总之，双频激发可以增加气泡空化和相关的加热，从而提高 HIFU 消融治疗大病变的效果。
