In vivo endoscopic optical coherence tomography of the human gastrointestinal tract - Toward optical biopsy

Background and Study Aims: Optical coherence tomography (OCT) is a new tech nique for high-resolution cross-sectional imaging using infrared light. It has over 10 times the resolution of the currently available ultrasonography , Although in vitro studies have suggested its potential for gastrointestin al imaging, in vivo studies have not been possible so far on account of tec hnical limitations. Patients and Methods: We describe here the first clinical study of OCT duri ng routine endoscopy obtaining high resolution images of the normal esophag eal, gastric, and colonic mucosa, Portable OCT equipment and a fiberoptic-b ased flexible probe for endoscopic use have been developed by the authors. Results: Differences in the optical properties of epithelium, lamina propri a, muscularis mucosae, and submucosa enabled distinction of the mucosal arc hitecture. Owing to the low penetration depth (1 mm) and high resolution (1 0 mu m), OCT images may become comparable to mucosal histological findings. Image acquisition time was 1.5 seconds, and the entire procedure was compl eted within 5 minutes. Endoscopic OCT images of colonic adenoma and carcino ma were also studied and compared with the corresponding histology. Conclusions: The newly developed portable OCT equipment and flexible fibero ptic probe makes OCT a promising method for endoscopic "optical biopsy".