OCT Patterns in Ulcerative Colitis

Abstract

Background and Aim: The Optical coherence tomography (OCT) is a new imaging technique providing high-resolution, real-time, cross-sectional images of microstructure of biological tissues. OCT produces images with high spatial resolution (≤ 10 microns), leading to a visualization of tissue substructure nearly equivalent to standard histology (“optical biopsy”). The OCT imaging depends on the optical properties of tissue. Previous studies with OCT on GI tract described mucosa, submucosa and microscopic structures, while studies on ulcerative colitis (UC) showed the disappearance of crypts and alteration in light backscattering. This study aimed to assess the OCT patterns in patients with UC and to show possible differences between active and quiescent disease. Patients and Methods: Thirty-seven subjects (20 M-17 F, 20-76 yrs) were enrolled; among them, 27 were UC patients and 10 were the control group. During a total colonoscopy, pts underwent real-time OCT imaging with a specific probe passed through the operative channel. The endoscopist collected OCT pictures from affected and normal areas in the colon (UC in remission, normal site above the affected site). Almost 200 OCT images (88-439) were collected for each patient. Then, to have the histological diagnosis, two biopsies in the same site were performed. Two endoscopists specifically trained scored the OCT patterns, whereas 2 pathologists blinded to the endoscopic and OCT features made the histological diagnosis. Results: The OCT imaging in the control group allowed to distinguish among OCT patterns of normal colonic wall and those of UC. The OCT features in the controls consisted of a regular and evident wall stratification (epithelium of glands, muscularis mucosae and submucosa) with regular and well-oriented crypts. The OCT patterns for UC where different based on disease activity. The UC in remission was almost similar to normal colon, except for the presence of altered backscattering areas in the epithelium (due to edema or chronic inflammation). In active disease, there was an increased backscattering alteration that impaired the visualization of wall layers and in particular of the muscolaris mucosae. Conclusions: The OCT technique has shown to be able to identify tissue microstructures, peculiar of UC both in activity or in remission. These features were confirmed by the histology and useful to distinguish between the inflamed (acute and chronic) and the normal colon.