OCT Performance in the Diagnosis of Ulcerative Colitis

Abstract

Background and Aim: The optical coherence tomography (OCT) is an imaging modality, similar to B-scan ultrasound apart from its image formation which relies on differences in optical (infrared light) rather than acoustic backscattering properties of tissue. The resolution of OCT is less than 20 μm, up to 10 times higher than ultrasonography. Studies of OCT on GI tract described mucosa, submucosa and microscopic structures, while studies on ulcerative colitis (UC) showed the disappearance of crypts and alteration in the backscattering of light. This study aimed to assess the feasibility and performance of OCT system in UC, comparing to the histology. Patients and Methods: Twenty-seven patients (15 M-12 F, 20-76 yrs) with UC were enrolled. The endoscopic diagnosis was: 2 pancolitis, 21 left colitis; 4 UC in remission. Twenty-five subjects matched for age and sex, with normal endoscopic and histological findings, constituted the control group. During a total colonoscopy, pts underwent real time OCT imaging with a middle focus OCT probe passed through the operative channel. The endoscopist collected OCT images from the pathologic colon (from 1 up to 6 sites) or from the areas of UC in remission, + 1 normal site above the affected site. After the OCT, two macrobiopsies in the same site were taken. In media 200 OCT images were collected for each patient (88-439). The OCT images were scored by 2 endoscopists trained and blinded to clinical, endoscopic and histological data. Further, 2 pathologists blinded to the endoscopic and OCT patterns red the samples. Results: The OCT images and histology showed pathological features (inflammation, disrupted epithelium) in the 27 pts when considering the affected segment or the affected segment in remission at the endoscopy. Regarding the OCT analysis and histology performed on normal sites above the affected segment, in 9/25 cases (36%) pathological features were recognized, with a good correspondence between OCT and histology. In the control group, normal features were identified at OCT and histology, except for some degree of oedema that was considered normal by the pathologists. Conclusions: The in vivo-OCT correctly detected pathological features in colon segments affected at the endoscopy, but even in 36% in apparently normal colon segments of UC-patients. This result opens new perspectives in the evaluation of UC and the problems related to its endoscopic surveillance.