Cavitation-enhanced ultrasound thermal therapy by combined low- and high-frequency ultrasound exposure
Cavitation-enhanced ultrasound thermal therapy by combined low- and high-frequency ultrasound exposure
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DOI：
10.1016/j.ultrasmedbio.2006.01.010
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发表时间：
2006-05-01
影响因子：
2.9
通讯作者：
Lin, Win-Li
中科院分区：
文献类型：
--
作者：
Liu, Hao-Li;Chen, Wen-Shiang;Lin, Win-Li
本文展示了一种利用低频和高频超声同时超声引入声空化来增强超声诱导加热的新方法。采用球形聚焦换能器（566或1155 kHz）产生热损伤，采用低频平面换能器（40或28 kHz）增强气泡活性。以离体新鲜猪肌肉为超声消融靶。利用pvdf型针状水听器记录了气泡在加热过程中的发射信号和后向散射信号，并插入热电偶进行温度测量。与单一聚焦换能器形成的病变相比，在566 khz和40 khz联合超声下，该方法产生的病变沿轴向的大小增加了140%，沿径向的大小增加了200%。在1155 khz和28 khz声波组合下，它们沿轴向和径向分别大47%和66%。低频超声增强的空化活动被频谱中亚谐波的存在和温度升高所证实，这是组织吸收增加的结果。这些观察结果表明，可以在不降低穿透能力的情况下产生空化增强病变；它们还显示出通过多次超声产生更大、更均匀的热损伤的优势。该技术提供了一种简单而有效的方法来实现空化强化加热，并且可能对产生大而深的热损伤有用。（E-mail: yychen@cc.ee.ntu.edu.tw） (c) 2006年世界医学和生物学超声联合会。
This paper demonstrates a novel approach for enhancing ultrasound-induced heating by the introduction of acoustic cavitation using simultaneous sonication with low- and high-frequency ultrasound. A spherical focused transducer (566 or 1155 kHz) was used to generate the thermal lesions, and a low-frequency planar transducer (40 or 28 kHz) was used to enhance the bubble activity. Ex vivo fresh porcine muscles were used as the target of ultrasound ablation. The emitted signals and the signals backscattered from the bubble activity were also recorded during the heating process by a PVDF-type needle hydrophone, and thermocouples were inserted to measure temperatures. Compared with the lesions formed by a single focused transducer, the size of the lesions generated by this approach were as much as 140% larger along the axial direction and 200% larger along the radial direction for combined 566- and 40-kHz sonication. They were 47% and 66 % larger along the axial and radial directions, respectively, for combined 1155- and 28-kHz sonication. Cavitation activities enhanced by low-frequency ultrasound were confirmed by the presence of subharmonics in the spectrum and temperature increase as a result of increased tissue absorption. These observations imply that cavitation-enhanced lesions can be generated without reducing the penetration ability; they also show the advantage of producing larger and more uniform thermal lesions by multiple sonications. This technique provides an easy and effective way to achieve cavitation-enhanced heating, and may be useful for generating large and deep-seated thermal lesions. (E-mail: yychen@cc.ee.ntu.edu.tw) (c) 2006 World Federation for Ultrasound in Medicine & Biology.