Real time endoscopic and functional imaging of biological ultrastructure using optical coherence tomography

Optical coherence tomography (OCT) is a relatively new, non-invasive optical imaging technique. OCT is well suited to in situ imaging of biological ultrastructure, providing micron-scale resolution in three dimensions to a depth of a few millimeters without contacting the tissue. The objective of this research was to advance the state of the art in OCT imaging in order to enable endoscopic examination of gastrointestinal mucosae, and to explore functional imaging extensions to the technology.; We present a high speed OCT system capable of imaging in real time. Issues critical to real time OCT imaging are discussed, with an emphasis on rapid scanning optical delay lines, and real time signal conditioning, acquisition, and display instrumentation. Results of experiments demonstrating real time OCT imaging are presented, including in vivo samples.; The real time OCT system was integrated with a custom catheter probe in a prototype endoscopic OCT (EOCT) unit appropriate for clinical studies. We report on the design and initial clinical experience with the real-time EOCT imaging system. Results of initial clinical studies are presented. EOCT imaging clearly delineates the substructure of the mucosa and submucosa in several gastrointestinal organs.; Color Doppler optical coherence tomography (CDOCT) is a functional extension of OCT that can image flow in turbid media with micron-scale spatial resolution. We present a real-time CDOCT system that is capable of imaging flow at high frame rates. Imaging of flow in tissue simulating phantom and in vivo in an animal model is demonstrated.; Further, we introduce a family of power-conserving fiber-optic interferometer designs for OCT. Simple design equations for optimization of the signal to noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters.; Finally, we discuss a number of future directions for OCT research. The spectroscopic OCT techniques of wavelength ratiometric OCT and dispersion measurement using OCT are proposed and discussed. Additional novel interferometer configurations are introduced for a variety of applications. The idea of angle resolved elastic scattering spectroscopy in the single-scattering regime using OCT is also introduced and discussed. Finally, a method of imaging action potentials using OCT is introduced and described.