High-magnification chromoscopic colonoscopy in ulcerative colitis: a valid tool for in vivo optical biopsy and assessment of disease extent

Background and study aims: Colonoscopy with mucosal biopsy is currently considered to be the "gold standard" investigation for the evaluation of disease activity and disease extent in ulcerative colitis. Conventional colonoscopic criteria are inadequate for assessing disease extent and for predicting clinical relapse, however. Histopathological markers of relapse, such as microscopic crypt abscess formation and mucin depletion cannot be identified using conventional endoscopy. The aim of this study was to evaluate the efficacy of high-magnification chromoscopic colonoscopy for the in vivo assessment of histopathological inflammation and disease extent using standardised endoscopic and histopathological criteria. Patients and methods: Total colonoscopy using the Olympus CF240Z magnifying colonoscope was performed prospectively in 325 consecutive patients with a known diagnosis of ulcerative colitis. A "biphasic" examination of all five colonic segments and the rectum was performed with conventional endoscopy followed by magnification imaging and biopsy. Disease activity was documented using Baron's classification, modified Saitoh criteria for magnification imaging, and Matts' histopathological grading. Results: A total of 1800 images from 300 patients were analyzed (25 patients were excluded). The kappa coefficients of agreement between Saitoh's magnification criteria grades 1/2, 3/4, and 5/6 and Matts' histopathological grades 1/2, 3a/b, and 4/5 were 0.96, 0.62, and 0.51, respectively. Mild, moderate, and severe histopathological disease (Matts' grades 1/2, 3a-4, and 5) were represented more accurately using Saitoh's criteria than by conventional Baron scores for all clinical parameters (r = 0.976; P < 0.001). Magnification imaging was significantly better than conventional colonoscopy for predicting disease extent in vivo (P < 0.0001). Conclusions: This is the largest prospective study and the only Western group to report on this application of magnification imaging. High-magnification imaging provides a sensitive and specific in vivo "virtual biopsy" in ulcerative colitis and so an instant biomarker for disease relapse, while accurately predicting disease extent. High-accuracy optical biopsy can limit the number of biopsies required, with significant cost savings for pathology services.