Real-time and functional optical coherence tomography

Optical Coherence Tomography (OCT) is a novel biomedical imaging technique which uses low-coherence optical interferometry to obtain micron-scale resolution tomographic images of sub-surface tissue structure noninvasively. We report on recent technical advances in OCT which have enhanced its potential for biological research and for minimally invasive medical diagnostics. We have developed OCT scanners compatible with minimally invasive delivery technologies (i.e., biomicroscopy, endoscopy) capable of imaging up to video rate. Clinical studies of OCT imaging in the eye, skin, and gastrointestinal tissues are under way which demonstrate the capability for quantitative morphometry on the micron scale, reproducible image contrast between tissue layers, and differentiation between normal and pathological tissue states. We have also developed novel functional imaging extensions to OCT including spectroscopic, Doppler flow, and polarization-sensitive enhancements which take advantage of the altered spectral or directional content of backscattered light to provide enhanced image contrast. Color Doppler Optical Coherence Tomography (CDOCT) is an extension to OCT which performs micron-scale resolution imaging flow velocimetry in biological tissues and other scattering media. We report on autocorrelation-based signal processing approaches for real-time rendering of Color Doppler OCT imagery in the physiological range of velocities from less than 1 min/sec to greater than 1 cm/sec. Demonstrated applications include the use of CDOCT for imaging of flow and flow dynamics in human retinal vessels, as well as intracardiac flow and turbulence in a developmental biology model.