Feasibility of optical coherence tomography for high-resolution imaging ofhuman gastrointestinal tract malignancies

Optical coherence tomography (OCT) is a new imaging,technology which can pe rform high-resolution, cross-sectional imaging of the internal microstructu re of biological tissues. OCT is analogous to ultrasound, except that it me asures the intensity of back-reflected infrared light rather than sound wav es. OCT performs two- and three-dimensional imaging of tissue microstructur e in situ and in real time. It can achieve image resolutions approaching th e cellular level over approximately the same imaging depths as a convention al biopsy. In this article we examine the feasibility of OCT for high-resol ution imaging of gastrointestinal malignancies with ex-vivo imaging of norm al and pathologic microstructures. Tissue, both normal and neoplastic, was obtained from patients undergoing surgical resection after an initial diagn osis of a gastrointestinal malignancy. The tissue samples were imaged prior to fixation using a laboratory OCT system. The OCT system consists of a fi ber optic-based Michelson interferometer, a commercially available amplifie d superluminscent light source, and a computer for data acquisition. The im ages were subsequently compared with histological cross-sections correspond ing to the imaged areas. The stratified squamous epithelium of the normal e sophagus was clearly visible in the OCT images and contrasted to the disorg anized and non-uniform nature of the mucosal layers of Barrett's esophagus and squamous carcinoma. The columnar epithelial morphology as well as other mucosal structures in normal colon were distinctly visible using OCT. In c ontrast, disorganization of the normal mucosal layers and ulcerative lesion s were identified in tissues from ulcerative colitis and adenocarcinoma of the colon. The ability of OCT to image tissue microstructure at high resolu tions makes it a potentially powerful technology for minimally invasive ass essment of the gastrointestinal tract and the evaluation of early neoplasti c changes.