Development of akinetic swept-source OCT for middle ear imaging

光学相干层析成像(OCT)是一种新兴的光学成像手段，可以产生组织的深度分辨图像。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。我的研究重点是将其用于成像更大的中耳体积。我的建议旨在开发中耳体积的快速实时2D成像技术，即多普勒OCT，以实现中耳对声音的反应的功能成像和鼓膜的3D成像。在过去的五年里，我的实验室建立了第一个OCT系统，能够以接近实时的帧速率(3FPS)获得人类中耳的图像。目前的提议将通过从时域OCT系统转移到去年已投入商业使用的新的无动力扫描激光系统来扩展这项工作。这种新的激光器提供了许多可以改善中耳成像的新功能--真正的实时帧速率(&gt；30FPS)、更大的扫描范围以及用于多普勒成像和合成孔径成像的出色的相位稳定性。*我的建议包括三个子项目：*1)开发覆盖整个中耳体积的实时2D(B模式)成像。这是我的团队通过充分利用新的无动力扫源OCT技术在耳部的亚实时OCT成像和实时高频超声成像方面所做的工作的扩展。它需要在高速数据处理和显示以及光学和采集电子学的重新设计方面的进步。*2)中耳实时多普勒振荡术的发展。这将是扫频源OCT的一种新的和独特的应用，利用无动力扫频源的高相位稳定性来实现前所未有的高扫描速度的多普勒测振。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在时间和空间上得到最佳平均。*3)鼓膜实时3D成像的开发。这种应用需要显著提高信噪比。为了获得这种改进，我提出了一种新的合成孔径OCT技术，该技术利用非动能扫描源激光器的任意扫频能力来显著降低合成孔径OCT的计算复杂性。该技术将通过使用平面波照明和检测，并在照明和检测方向之间的角度可控的情况下，直接对图像的3D傅立叶变换进行采样。*虽然本研究的重点是中耳成像，但本研究计划中OCT技术的进展可以广泛地惠及其他应用，特别是需要大扫描体积、高帧频和/或振动成像的应用。这包括全眼光学成像，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. **