Development of akinetic swept-source OCT for middle ear imaging

光学相干断层扫描（OCT）是一种新兴的光学成像方式，可以产生组织的深度分辨率图像。OCT在视网膜和皮肤的小体积成像应用中得到了很好的应用。我的研究重点是用它来成像中耳更大的体积。我的建议旨在开发中耳容量的快速实时2D成像技术，多普勒OCT技术，以实现中耳对声音反应的功能成像和鼓膜的3D成像。在过去的五年里，我的实验室已经建立了第一个能够以接近实时帧率（3FPS）获得人类中耳图像的OCT系统。目前的提案将通过从时域OCT系统转移到去年已商业化的新型动力学扫描激光系统来扩展这项工作。这种新型激光器提供了许多新功能，可以改善中耳成像-真正的实时帧率（bbb30fps），更长的扫描范围和多普勒成像和合成孔径成像的特殊相位稳定性。******我的建议包括三个子项目：******1)开发整个中耳体积的实时2D （b模式）成像。本研究充分利用新的动态扫源OCT技术，扩展了我课组之前在耳部亚实时OCT成像和实时高频超声成像方面的工作。它需要在高速数据处理和显示以及光学和采集电子的重新设计方面取得进步。***2)中耳实时多普勒振动仪的发展。这将是一种新的、独特的扫描源OCT应用，利用动力扫描源的高相位稳定性，为多普勒振动测量实现前所未有的高扫描率。中耳多普勒OCT将需要开发快速计算机视觉算法来识别中耳体积内的振动结构，以便对结构速度的重复测量可以在时间和空间上进行最佳平均。***3)鼓膜实时三维成像技术的发展。这种应用需要显著提高信噪比。为了实现这一改进，我提出了一种新的合成孔径OCT技术，该技术利用动态扫频源激光器的任意扫频能力，大大降低了合成孔径OCT的计算复杂度。该技术将通过平面波照明和检测直接对图像进行三维傅里叶变换采样，照明和检测方向之间的角度可控制。***虽然这项研究的重点是中耳成像，但在这项研究计划中，OCT技术的进步可以广泛地造福于其他应用，特别是那些需要大扫描体积、高帧率和/或振动成像的应用。这些包括全眼成像、呼吸道成像和工业自动化检查和测试。**

Optical coherence tomography (OCT) is an emerging optical imaging modality that can produce depth-resolved images of tissue. OCT is well-established in small-volume imaging applications in the retina and skin. My research is focused on its use for imaging the much larger volume of the middle ear. My proposal aims to develop techniques for fast real-time 2D imaging of the middle ear volume, Doppler OCT to enable functional imaging of the middle ear's response to sound and 3D imaging of the eardrum. Over the past five years my lab has built the first OCT system capable of obtaining images of the human middle ear at near real-time frame rates (3FPS). The current proposal will extend that work by moving from a time-domain OCT system to a new, akinetic swept-laser system that has become commercially available in the last year. This new laser offers many new capabilities that can improve middle ear imaging - true real time frame rates (>30FPS), a longer scanning range and exceptional phase stability for Doppler imaging and synthetic aperture imaging.******My proposal consists of three sub-projects:******1) Development of real-time 2D (B-mode) imaging over the entire middle ear volume. This extends previous work by my group on sub-real-time OCT imaging and real-time high-frequency ultrasound imaging of the ear, by taking full advantage of new akinetic swept-source OCT technology.  It requires advances in high-speed data processing and display as well redesign of optics and acquisition electronics.***2) Development of real-time Doppler vibrobraphy of the middle ear. This will be a new and unique application of swept-source OCT, exploiting the high phase stability of akinetic swept sources to achieve unprecedented high scan rates for Doppler vibrometry.  Middle ear Doppler OCT will require development of fast computer vision algorithms to recognize vibrating structures within the middle ear volume so that repeated measurements of the velocity of structures can be optimally averaged in time and space. ***3) Development of real-time 3D imaging of the tympanic membrane. This application will require a significant improvement in SNR.  To obtain this improvement I propose a novel synthetic aperture OCT technique that exploits the arbitrary frequency sweeping capability of akinetic swept source lasers to drastically reduce the computational complexity of synthetic aperture OCT.  The technique will directly sample the 3D Fourier Transform of the image by using plane wave illumination and detection with a controllable angle between the illumination and detection directions.***While the focus of this research is middle ear imaging, advances made in OCT technology in this research program can broadly benefit other applications, particularly those requiring large scanning volumes, high frame rates and/or vibrography.  These include whole-eye opthalmic imaging, respiratory tract imaging and industrial automated inspection and testing. **