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

项目摘要 青光眼是世界范围内导致不可逆转失明的主要原因，影响着超过220万美国人。带着一个 随着人口老龄化，预计到2020年青光眼患者将达到8000万 全世界有1100万人双眼失明。尽管眼压升高(IOP)是主要风险 青光眼视神经损害的发生因素及眼压升高的机制 最终导致损害的原因仍不清楚。因此，需要开发新的非侵入性成像 可以测量后巩膜的基本力学性能的模式，并表征 它们如何对患者造成损害，特别是与年龄、种族和青光眼严重程度有关时 损坏。这种工具将是眼科研究和临床实践中向前迈出的重要一步，提供 根据人和眼睛的特定特征评估疾病风险的迫切需要的能力。 本研究的目标是开发一种新型的基于高分辨率超声的无创成像平台 测量后巩膜的生物力学性能。为了解决这一目标，我们提出了两种成像系统 利用双频配置。一个系统由低频(4.5 MHz)环形换能器组成 用来“推动”组织，内部有一个针形单元件换能器来“跟踪”微米级的位移；另一个 系统采用高频单晶线性相控阵作为接收器来代替针式换能器 用于弹性成像，首先获得实时和高速的后巩膜弹性成像。 2D/3D声辐射力脉冲(ARFI)成像和剪切波弹性成像(Swei)将 在体外未刻度的兔巩膜上进行手术，将预先加载不同的眼压水平以进行评估。我们的 初步结果验证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 通过相关横波的传播速度进行量化组织硬度测量的成像 可以潜在地使我们能够详细地描述年龄和性别之间的联系 巩膜的特性，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