Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.
J Acoust Soc Am. 2012 Jun;131(6):4349-57. doi: 10.1121/1.4707479.
The oscillation and destruction of microbubbles under ultrasound excitation form the basis of contrast enhanced ultrasound imaging and microbubble assisted drug and gene delivery. A typical microbubble has a size of a few micrometers and consists of a gas core encapsulated by a shell. These bubbles can be driven into surface mode oscillations, which not only contribute to the measured acoustic signal but can lead to bubble destruction. Existing models of surface model oscillations have not considered the effects of a bubble shell. In this study a model was developed to study the surface mode oscillations in shelled bubbles. The effects of shell viscosity and elasticity on the surface mode oscillations were modeled using a Boussinesq-Scriven approach. Simulation was conducted using the model with various bubble sizes and driving acoustic pressures. The occurrence of surface modes and the number of ultrasound cycles needed for the occurrence were calculated. The simulation results show a significant difference between shelled bubbles and shell free bubbles. The shelled bubbles have reduced surface mode amplitudes and a narrower bubble size range within which these modes develop compared to shell free bubbles. The clinical implications were also discussed.
超声激发下微泡的振荡和破坏是对比增强超声成像和微泡辅助药物及基因传递的基础。典型的微泡大小为几个微米，由外壳包裹的气体核组成。这些气泡可以被驱动进入表面模式振荡，这不仅有助于测量声信号，而且可能导致气泡破裂。现有的表面模式振荡模型没有考虑气泡壳的影响。在这项研究中，开发了一个模型来研究壳层微泡的表面模式振荡。使用 Boussinesq-Scriven 方法对壳层粘性和弹性对表面模式振荡的影响进行建模。使用不同气泡尺寸和驱动声压的模型进行了模拟。计算了表面模式的发生和发生所需的超声循环数。模拟结果表明，壳层气泡和无壳气泡之间存在显著差异。与无壳气泡相比，壳层气泡的表面模式幅度降低，并且在这些模式发展的气泡尺寸范围内更窄。还讨论了临床意义。
