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

Abstract

Optical coherence tomography (OCT) is a new technique 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 gastrointestinal imaging, in vivo studies have not been possible so far on account of technical limitations. We describe here the first clinical study of OCT during routine endoscopy obtaining high resolution images of the normal esophageal, gastric, and colonic mucosa. Portable OCT equipment and a fiberoptic-based flexible probe for endoscopic use have been developed by the authors. Differences in the optical properties of epithelium, lamina propria, muscularis mucosae, and submucosa enabled distinction of the mucosal architecture. Owing to the low penetration depth (1 mm) and high resolution (10 microm), OCT images may become comparable to mucosal histological findings. Image acquisition time was 1.5 seconds, and the entire procedure was completed within 5 minutes. Endoscopic OCT images of colonic adenoma and carcinoma were also studied and compared with the corresponding histology. The newly developed portable OCT equipment and flexible fiberoptic probe makes OCT a promising method for endoscopic "optical biopsy".