Biomechanical mapping of the optic nerve head and peripapillary sclera using high frequency ultrasonic elastography

项目摘要 青光眼是全球不可逆失明的主要原因，影响超过220万美国人。与 人口老龄化，预计到2020年青光眼患者人数将达到80万 全世界有1100万人左右失明。虽然眼内压升高（IOP）是主要风险 青光眼视神经损伤的发展因素，眼压升高的机制， 最终导致的损害尚不清楚。因此，需要开发新的非侵入性成像 可以测量后巩膜的基本机械特性并表征 它们如何导致患者的损害，特别是与年龄、种族和脑水肿严重程度有关的损害。 损害这种工具将是眼科研究和临床实践的重要一步， 根据人和眼睛的具体特征评估疾病风险的能力。 本研究的目的是开发一种新型的高分辨率超声成像平台， 测量后巩膜的生物力学特性。为了实现这一目标，我们提出了两个成像系统 利用双频配置。一个系统由低频（4.5 MHz）环形换能器组成 “推动”组织，内部有一个针形单元件传感器，用于“跟踪”微米级位移;另一个 系统是用高频单晶线阵作为接收器来取代针状换能器 对于弹性成像，首先获取后巩膜的真实的实时和高速弹性成像。 2D/3D声辐射力脉冲（ARFI）成像和剪切波弹性成像（SWEI）将在 在离体未定标的兔巩膜上进行，所述兔巩膜将预加载各种IOP水平以用于评价。我们 初步结果证实了双频超声弹性成像的原理 获得巩膜和角膜生物力学特性的技术。集成高分辨率ARFI 通过相关联的剪切波的传播速度利用量化的组织硬度测量进行成像 可以让我们详细描述年龄和性别之间的联系， 巩膜的性质，使我们能够探索与青光眼的关系

Project Summary Glaucoma is a leading cause of irreversible blindness worldwide, affecting over 2.2 million Americans. With an aging population, it is estimated that by 2020 the number of people suffering from glaucoma will reach 80 million worldwide, with 11 million being bilaterally blind. Although elevated intraocular pressure (IOP) is the primary risk factor for the development of glaucomatous optic nerve damage , the mechanisms by which elevated IOP eventually leads to damage are still unclear. Thus, there is a need to develop novel non-invasive imaging modalities that can measure the fundamental mechanical properties of the posterior sclera, and characterize how they contribute to damage in patients particularly as it relates to age, race, and severity of glaucomatous damage. Such a tool would be an important step forward in ocular research and clinical practice, providing the much-needed ability to evaluate the risk of disease based on person- and eye-specific characteristics. The goal of this study is to develop a novel high-resolution ultrasound-based imaging platform non-invasively measure biomechanical properties of the posterior sclera. To address this goal, we propose two imaging systems utilizing dual frequency configuration. One system consists of a low-frequency (4.5 MHz) ring shape transducer to “push” the tissue, and a needle single element transducer inside to “track” micron-level displacement; Another system is to replace the needle transducer with a high-frequency single crystal linear phased array as receiver for elastography imaging to first acquire real time and high speed elastography imaging of the posterior sclera. 2D/3D acoustic radiation force impulse (ARFI) imaging and shear wave elasticity imaging (SWEI) will be performed on ex-vivo unscaled rabbit sclera that will be preloaded with various IOP levels for evaluation. Our preliminary results have demonstrated the principle of using the dual frequency ultrasonic elastography technique on obtaining the biomechanical properties of the sclera and cornea. Integrating high-resolution ARFI imaging with quantified tissue stiffness measurements via the propagation speed of the associated shear wave can potentially allow us to characterize in detail the association between age and gender on the mechanical properties of the sclera and allow us to explore the relationship with glaucoma