Development of akinetic swept-source OCT for middle ear imaging

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.