Micron-resolution sub-surface imaging of the gastrointestinal tract wall with optical coherence tomography
BACKGROUND/PURPOSE: A new technique called optical coherence tomography (OCT) has been developed for non-invasive imaging of subsurface biological structure with high resolution (-10 microns) and high dynamic range (>100 dB). OCT is similar to B-scan ultrasonography, except that infrared light rather than ultrasound is used to obtain higher image resolution without requiring tissue contact with the imaging probe. In preliminary in vitro imaging studies, we assess the potential of OCT for high-resolution endoscopic imaging of the gastrointestinal (GI) tract wall. METHODS: Cross-sectional images of internal tissue microstructure were obtained at selected sites on excised tissue samples using OCT. Tissue samples studied included postmortem normal porcine esophagus and colon, surgical resections of normal human esophagus and colon, and abnormal human colon (adenocarcinoma and Crohn's disease). After imaging, the OCT scan locations were carefully marked on the tissue surface, and 10 micron cryostat sections corresponding to the cross-sectional images were obtained. The OCT images were compared with histology. RESULTS: In OCT images in porcine tissue, we observed clear delineation of the mucosa and submucosa in the esophagus and colon. In addition, substructure of the mucosa, including stratified squamous epithelium, lamina propria, and muscularis mucosae, were observed in esophagus. Mucosa, muscularis mucosae, and submucosa were identified in most human colon specimens. Lymphocyte aggregation in the mucosa and inflammation of the mucosa and submucosa were also observed in human colon. Because the penetration depth of OCT imaging is limited to 2-3 mm, muscle layers and serosae were not visualized. CONCLUSION: OCT is a potentially useful diagnostic technique for high-resolution imaging and evaluation of mucosal and submucosal pathology of the GI tract wall.
Kobayashi, K; Wang, HS; Sivak, MV; Izatt, JA
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