Elasticity Imaging and Sensing using Gas Bubble Dynamics

描述（由申请人提供）：我们计划的总体目标是开发一种成像技术，以基于气泡动力学评估组织的粘弹性，并且通常在几种生物医学技术的背景下了解粘弹性介质中的气泡动力学。事实上，微泡在生物医学和临床应用中发挥着越来越重要的作用，其中微泡不仅被引入液体中，而且被引入生物软组织中。虽然液体中的气泡动力学已被很好地理解，但组织中气泡的行为还不清楚。然而，这样的理解可以导致开发新的和现有的生物医学技术的基础上，如何在粘弹性介质中的气泡行为和气泡如何响应内部或外部激励的改进。在当前的项目中，我们将把注意力集中在眼组织的激光显微手术上，其中由于激光与组织相互作用而产生的气泡用于切割组织。气体微泡行为的远程、非侵入性、高时间和空间分辨率、实时测量可用于在手术前、手术期间和手术后对眼组织急需的机械特性进行成像或传感。对粘弹性介质中气泡动力学进行了理论、数值和实验研究。我们将建立一个不可压缩弹性介质中气泡径向振动的非线性模型。所开发的模型将考虑内部气体压力和软组织的复杂性，包括轻微的可压缩性，组织粘度，组织弹性的异质性和各向异性。我们还将研究被动气泡动力学和气泡平移运动和振荡响应于外部激励，如声辐射力。接下来，我们将开发能够测量气泡的时间和空间行为的超声波和光学技术。给出这些测量，将开发用于估计气泡周围组织的弹性（杨氏模量或剪切模量）和粘度的算法。最后，我们将进行实验室研究，以验证我们的模型，并证明我们的方法的能力，图像或感测粘弹性的眼组织使用气泡动力学。因此，所有的理论和实验研究将进行评估的适用性开发的方法用于眼科应用。

DESCRIPTION (provided by applicant): The overall goal of our program is to develop an imaging technology to assess viscoelastic properties of tissue based on gas bubble dynamics, and, generally, to understand the gas bubble dynamics in viscoelastic medium in the context of several biomedical technologies. Indeed, microbubbles are playing an increasingly important role in biomedical and clinical applications where microbubbles are introduced not only in liquids but also in biological soft tissues. While bubble dynamics in liquid is well understood, the behavior of bubbles in tissue is not. However, such an understanding can lead to the development of novel and improvement of existing biomedical techniques based on how bubbles behave in a viscoelastic medium and how the bubble responds to internal or external excitation. In the current project, we will focus our attention on laser microsurgery of the eye tissue where the bubbles, produced as a result of laser-tissue interaction, are used to cut tissue. The remote, non-invasive, high temporal and spatial resolution, real-time measurements of gas microbubble behavior can be used to image or sense much needed mechanical properties of the eye tissues prior, during and after the surgery. Theoretical, numerical, and experimental studies of gas bubble dynamics in viscoelastic medium are proposed. We will develop a nonlinear model of radial oscillations of a gas bubble in an incompressible elastic medium. The developed model will account for internal gas pressure and the complexity of soft tissue including slight compressibility, tissue viscosity, and tissue elastic heterogeneity and anisotropy. We will also investigate passive bubble dynamics and bubble translational motion and oscillations in response to external excitation such as acoustic radiation force. Next, we will develop ultrasonic and optical techniques capable of measuring the temporal and spatial behavior of the gas bubble. Given these measurements, the algorithms to estimate elasticity (Young's or shear modulus) and viscosity of the tissue surrounding the bubble will be developed. Finally, we will perform laboratory studies to verify our model and to demonstrate the ability of our method to image or sense viscoelasticity of ocular tissues using gas bubble dynamics. Therefore, all theoretical and experimental studies will be conducted to evaluate applicability of the developed methods for ophthalmologic applications.