Holography-based Photoacoustic Imaging of the Retina

这项拟议的研究将评估一种用于光声成像的新型全光学技术的可行性，该技术 使用光折变晶体(PRC)，潜在地可以提供解剖和功能图像 视网膜、脉络膜和视神经具有超精细分辨率。视网膜亚结构的详细可视化和 视神经对于评估诸如糖尿病视网膜病变(DR)、年龄相关的眼科疾病至关重要 黄斑变性(AMD)和青光眼。然而，血管功能和局部氧气输送也是 疾病状态的相关指标。现有的诊断模式，如光学相干断层扫描 (OCT)和超声波(美国)不提供此信息。 我们在中国实施的PAI将解决其他成像模式的缺点，同时提供 图像分辨率为亚微米，成像深度是OCT的3到5倍。此外，PAI还可以 提供功能信息，如血红蛋白-血氧饱和度水平，可改善临床 眼科疾病的评估。我们的方法不需要流体耦合或物理接触 我们。由于所提出的PAI的全息实现使用了连续波激光器和基于CCD的 全场干涉法用于检测光声(PA)信号，它有可能在500 毫秒(仅受摄像机的帧速率和PA信号检测所需带宽的限制)。电荷耦合器件- 基于实现还便于通过简单地通过改变来修改视野(FOV)和分辨率 用来将光束引导到视网膜的显微镜物镜。可以达到规定的视场 通过调整人工晶状体与外部物镜之间的距离。 原型系统的性能将使用组织模拟模体来表征。后来， 使用活体动物，我们将演示我们的技术描绘视网膜/脉络膜微循环的能力。 与氧饱和度改变相关的视网膜色素上皮微结构和功能改变。 定量配给。使用建议的方法获得的图像将与眼底光学图像和组织学进行比较- 以事实为基础。成功完成拟议的研究将为开发多用途的 眼科成像系统，可用于临床前研究，使用各种动物模型， 并最终应用于临床成像。

The proposed study will assess the feasibility of a novel, all-optical technique for photoacoustic imaging that employs a photorefractive crystal (PRC) and potentially can provide anatomical and functional images of the retina, choroid, and the optic nerve with ultra-fine-resolution. Detailed visualization of retinal substructures and the optic nerve is critical for evaluation of ophthalmic diseases such as diabetic retinopathy (DR), age-related macular degeneration (AMD) and glaucoma. However, vascular function and local oxygen delivery also are relevant indicators of the diseased state. Existing diagnostic modalities such as optical coherence tomography (OCT) and ultrasound (US) do not provide this information. Our PRC-based implementation of PAI will address the shortcomings of other imaging modalities while providing sub-micron image resolution and an imaging depth that is 3 to 5 times that of OCT. Furthermore, PAI also can provide functional information such as the level of hemoglobin-oxygen saturation, which can improve clinical assessment of ophthalmic diseases. Our approach does not require fluid coupling or physical contact required by US. Because the proposed holographic implementation of PAI employs a continuous-wave laser and CCD-based full-field interferometry for detecting the photoacoustic (PA) signal, it potentially can acquire 3D-image data in 500 ms (limited only by the frame rate of the camera and the desired bandwidth for PA-signal detection). The CCD- based implementation also facilitates modification of the field of view (FOV) and resolution simply by changing the microscope objective employed to direct the optical beams to the retina. A prescribed FOV can be achieved by adjusting the distance between the ocular lens and the external objective. The performance of a prototypical system will be characterized using tissue-mimicking phantoms. Subsequently, using live animals, we will demonstrate the ability of our techniques to depict retinal/choroidal micro-circulation and the retinal-pigmented epithelium microstructure as well as functional changes related to altered oxygen satu- ration. Images obtained using the proposed methods will be compared with optical fundus images and histology- based ground truth. Successful completion of the proposed study will establish a basis for developing a versatile system for ophthalmic imaging that can be employed in pre-clinical research using a variety of animal models, and ultimately in clinical imaging.