Optical Coherence Tomography: Overview and Applications

Optical coherence tomography (OCT) is a rapidly emerging, noninvasive biomedical imaging technology (Drexler and Fujimoto 2008a; Huang et al. 1991). By utilizing interferometry-based optical gating to differentiate light signals reflected at different depths, OCT provides 2D cross-sectional and 3D volumetric images of inner structures in scattering biological samples. It generates images based on the spatial variation in refractive index, with no need for exogenous tracers and special sample preparation or tissue excision. In comparison with other prevailing in vivo imaging tools, OCT is advantageous in that it has better resolution (up to 1–2 μm) than ultrasound and magnetic resonance imaging (MRI), has higher imaging depth (1–2 mm in highly scattering tissues) than confocal and two-photon microscopes, and is not based on ionizing radiation such as is used in x-ray computed tomography (CT). As a rapidly evolving technology, OCT has the potential to complement or even replace the role in medical diagnosis and regenerative medicine that histological analysis has occupied, wherein complex sample preparation and long processing times are required, and which often rely on the subjective experience of individuals.