Medical Ultrasonics Laboratory (MEDUSA), Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, 02150, Finland.
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, M5S 1A8, Canada.
J Acoust Soc Am. 2022 Jun;151(6):3690. doi: 10.1121/10.0010534.
Ultrasonic cavitation is being used in medical applications as a way to influence matter, such as tissue or drug vehicles, on a micro-scale. Oscillating or collapsing cavitation bubbles provide transient mechanical force fields, which can, e.g., fractionate soft tissue or even disintegrate solid objects, such as calculi. Our recent study demonstrates that an ultrasonically actuated medical needle can create cavitation phenomena inside water. However, the presence and behavior of cavitation and related bioeffects in diagnostic and therapeutic applications with ultrasonically actuated needles are not known. Using simulations, we demonstrate numerically and experimentally the cavitation phenomena near ultrasonically actuated needles. We define the cavitation onset within a liver tissue model with different total acoustic power levels. We directly visualize and quantitatively characterize cavitation events generated by the ultrasonic needle in thin fresh bovine liver sections enabled by high-speed imaging. On a qualitative basis, the numerical and experimental results show a close resemblance in threshold and spatial distribution of cavitation. These findings are crucial for developing new methods and technologies employing ultrasonically actuated fine needles, such as ultrasound-enhanced fine-needle biopsy, drug delivery, and histotripsy.
超声空化正在医学应用中被用作一种在微观尺度上影响物质（如组织或药物载体）的方法。振荡或溃灭的空化气泡提供瞬态机械力场，例如可以将软组织分割，甚至使固体物体（如结石）解体。我们最近的研究表明，超声驱动的医用针可以在水中产生空化现象。然而，在诊断和治疗应用中，超声驱动针的空化现象及其相关生物效应尚不清楚。我们使用模拟，数值和实验证明了超声驱动针附近的空化现象。我们使用不同的总声功率水平定义了在肝组织模型中的空化起始。我们通过高速成像，直接可视化和定量表征超声针产生的空化事件在薄的新鲜牛肝切片上。定性地，数值和实验结果表明空化的阈值和空间分布非常相似。这些发现对于开发新的方法和技术至关重要，这些方法和技术采用超声驱动的细针，例如超声增强的细针活检、药物输送和组织破碎。
