Optical coherence tomography and microscopy in gastrointestinal tissues

Optical coherence tomography (OCT) and optical coherence microscopy (OCM) are novel techniques for noninvasive biomedical imaging based on low-coherence interferometry. OCT achieves high-spatial resolution (<30 /spl mu/m in three dimensions) and high dynamic range (>100 dB) in a fiber-optically integrated system which is suitable for application in minimally invasive diagnostics, including endoscopy. The technique of OCM combines the depth-ranging capability of OCT with the micron-scale resolution imaging capability of confocal microscopy to extend the available imaging depth of confocal microscopy up to several hundred micrometers deep in highly scattering tissues. The theoretical and technical bases for OCT and OCM imaging are described. Example OCT images are provided in gastrointestinal (GI) tissues to illustrate contrast between histological layers of the GI mucosa and differentiation of the mucosa from submucosa. Example OCM images revealing cellular-level microstructure up to several hundred micrometers deep in GI tissue are presented for the first time. The potential applications of OCT and OCM imaging in clinical diagnostic medicine are discussed.