High-resolution endoscopic imaging of the GI tract using optical coherencetomography

Background: Optical coherence tomography (OCT) has demonstrated the microsc opic structure of the gastrointestinal (GI) tract mucosa and submucosa in v itro. We evaluated a prototype OCT system and assessed the feasibility of O CT in the human GI tract. Methods: The 2.4 mm diameter prototype OCT probe, inserted through an endos cope, provides a 360-degree radial scan. Images (6.7 frames/sec) are displa yed on a television monitor. Tissue contact is not required. in patients un dergoing elective endoscopy, OCT images were obtained of normal mucosa (con firmed by biopsy). Results: Seventy-two sites were imaged (38 patients): esophagus (21), stoma ch (12), duodenum (11), terminal ileum (4), colon (15), and rectum (9), Var ying the distance between the probe and the mucosal surface produced images of the GI wall of varying depth. When held about 1 mm above the mucosal su rface, the images consisted of mucosal structures such as colonic crypts, g astric pits, and duodenal villi. With the probe held against the wall, the OCT image comprised several layers interpreted as mucosa, muscularis mucosa e, and submucosa, Structures including blood vessels were evident within th e submucosa. A probe with a 0.5 mm working distance to the focal point prov ided the best images. Reducing the frame rate to 4.0 per second facilitated image interpretation. Conclusions: OCT is feasible in the human GI tract and provides interpretab le high-resolution images of mucosa and submucosa.