Effects of nonlinear propagation, cavitation, and boiling in lesion formation by high intensity focused ultrasound in a gel phantom
Effects of nonlinear propagation, cavitation, and boiling in lesion formation by high intensity focused ultrasound in a gel phantom
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DOI：
10.1121/1.2161440
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发表时间：
2006-03-01
影响因子：
2.4
通讯作者：
Crum, LA
中科院分区：
文献类型：
--
作者：
Khokhlova, VA;Bailey, MR;Crum, LA
在透明蛋白凝胶中研究了非线性声波传播和超声诱导空化在高强度聚焦超声热损伤加速过程中的重要性。采用考虑非线性声传播的数值模型模拟实验条件。对单个病变和通过移动换能器获得的病变条纹进行了超声总能量相等但峰值声压可变的不同暴露机制研究。采用静超压抑制空化。在高振幅波中观察到病变产生的强烈增强，并得到了模型的支持。超压实验表明，非线性传播机制和空化机制都参与了加速损伤发生和生长的过程。在正常环境压力下，b超观察到病灶区域的空化，回声增强微弱，但在超压下未发现空化。蝌蚪状病变的形成，向换能器移动，总是观察到由于煮沸。凝胶中可见沸腾气泡，在b型图像中可见强回声区。这些实验表明，非线性传播和空化加速了加热，但在没有沸腾的情况下没有观察到损伤位移或变形。(c) 2006年美国声学学会。
The importance of nonlinear acoustic wave propagation and ultrasound-induced cavitation in the acceleration of thermal lesion production by high intensity focused ultrasound was investigated experimentally and theoretically in a transparent protein-containing gel. A numerical model that accounted for nonlinear acoustic propagation was used to simulate experimental conditions. Various exposure regimes with equal total ultrasound energy but variable peak acoustic pressure were studied for single lesions and lesion stripes obtained by moving the transducer. Static overpressure was applied to suppress cavitation. Strong enhancement of lesion production was observed for high amplitude waves and was supported by modeling. Through overpressure experiments it was shown that both nonlinear propagation and cavitation mechanisms participate in accelerating lesion inception and growth. Using B-mode ultrasound, cavitation was observed at normal ambient pressure as weakly enhanced echogenicity in the focal region, but was not detected with overpressure. Formation of tadpole-shaped lesions, shifted toward the transducer, was always observed to be due to boiling. Boiling bubbles were visible in the gel and were evident as strongly echogenic regions in B-mode images. These experiments indicate that nonlinear propagation and cavitation accelerate heating, but no lesion displacement or distortion was observed in the absence of boiling. (c) 2006 Acoustical Society of America.