High intensity focused ultrasound (HIFU) has gained increasing attention as a noninvasive therapeutic method for wide range of biomedical applications from drug delivery to cancer treatment. However, high level of ultrasonic power required for efficient HIFU treatment can cause adverse effects such as damage to surrounding healthy tissues and skin burns. One of the strategies to improve the therapeutic mechanism of HIFU is to use ultrasound absorption agents during the treatment. The objectives of current study are to investigate the feasibility of adopting gold nanoparticles (AuNPs) as ultrasound absorption agents to enhance the HIFU thermal ablation when the NPs were injected locally to the focal region; and to examine the dose effects of AuNPs on both heating and cooling mechanisms of HIFU. To this end, we conducted an experimental study on tissue-mimicking phantoms where AuNPs were injected to the focal region under the guidance of ultrasound imaging. A set of thermal parameters including temperature, specific absorption rate of acoustic energy, and cooling rate were measured to monitor the mechanism of AuNPs-mediated HIFU. The results suggest that both heating and cooling rates of HIFU procedure could be greatly improved by injecting AuNPs, which demonstrates the feasibility of using AuNPs to reduce the level of ultrasonic power from extracorporeal source for HIFU treatment.

中文翻译：

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使用金纳米粒子增强聚焦超声治疗的热效应。

作为一种无创治疗方法，高强度聚焦超声（HIFU）作为一种无创治疗方法，已广泛应用于从药物输送到癌症治疗的各种生物医学应用中。但是，高效HIFU治疗所需的高水平超声波功率会引起不利影响，例如对周围健康组织的损害和皮肤灼伤。改善HIFU治疗机制的策略之一是在治疗期间使用超声吸收剂。当前研究的目的是研究将金纳米颗粒局部注入病灶区域时，采用金纳米颗粒（AuNPs）作为超声吸收剂来增强HIFU热消融的可行性；并研究AuNPs对HIFU加热和冷却机理的剂量影响。为此，我们对组织模拟体模进行了实验研究，其中在超声成像的指导下将AuNPs注入到焦点区域。测量了一组热参数，包括温度，声能的比吸收率和冷却率，以监测AuNPs介导的HIFU的机理。结果表明，通过注射AuNPs可以大大提高HIFU程序的加热和冷却速率，这表明使用AuNPs降低体外来源HIFU治疗的超声功率水平的可行性。测量冷却速率并监测AuNPs介导的HIFU的机制。结果表明，通过注入AuNPs可以大大提高HIFU程序的加热和冷却速率，这表明使用AuNPs降低体外来源的HIFU治疗超声功率的可行性。测量冷却速率并监测AuNPs介导的HIFU的机制。结果表明，通过注入AuNPs可以大大提高HIFU程序的加热和冷却速率，这表明使用AuNPs降低体外来源的HIFU治疗超声功率的可行性。