Research And Application Of OCT Angiography

Spectral domain optical coherence tomography (SD-OCT), which is developed from optical coherence tomography (OCT), enables three-dimensional tissue structure imaging in non-invasive, label-free, high-speed, high-resolution, high-sensitivity and depth-resolved manners. OCT angiography (Angio-OCT), as one of the most important functional extensions of SD-OCT, is capable of providing physiological information (i.e. the visualization of microvascular networks and the quantification of the blood flow) in addition to morphological structure of tissues, which plays a significant role in the field of biomedical study and clinical application. This dissertation is mainly focused on the study of SD-OCT-based Angio-OCT technology and its main work could be summarized as,1. The primary imaging theory and the key system parameters of SD-OCT technology were deeply studied, and a SD-OCT system used for this study was then designed and homebuilt, theoretically offering a axial resolution of-3.2μm, a lateral resolution of～15μm, a depth of field of～0.83mm, a maximum imaging depth of-2.9mm and a maximum signal-to-noise ratio of～104dB.2. The merits and drawbacks of various Angio-OCT methods that have been developed by different groups worldwide were deeply studied, and a complex correlation-based Angio-OCT (CC-Angio-OCT) was then proposed. It was demonstrated by both theory and experiment that CC-Angio-OCT could offer a higher motion contrast and processing efficiency in comparison with the other Angio-OCT methods.3. The development of tissue optical clearing (TOC) technology was deeply investigated, and an Angio-OCT-based method was then presented for the study of optical clearing agents (OCAs). Through in vivo qualitative evaluation of the changes in imaging quality (mainly refer to the image contrast and imaging depth) and quantitative analysis of the changes in optical parameters (mainly refer to the attenuation coefficient, refractive index mismatching extent and correlation between OCT signal strength and refractive index mismatching extent) of tissues before and after OCA treatment, the intrinsic optical clearing mechanisms of OCAs could be explained. In the meanwhile, with the combination of TOC technology and Angio-OCT technology, the vasoactive drug-induced changes in vascular parameters (mainly refer to the vessel diameter and blood flux) within in vivo high-scattering tissues were further studied.