Magnifying colonoscopy with narrow band imaging system for the diagnosis of dysplasia in ulcerative colitis: a pilot study

Background: Narrow-band imaging (NBI) is a novel illumination technology for endoscopy that enhances vasculature of the GI tract. Objective: The aim was to elucidate whether NBI colonoscopy can identify dysplasia in patients with ulcerative colitis (UC). Design: Cross-sectional study of eligible patients. Setting: Single center. Patients: 46 patients with UC. Interventions: Apparently flat mucosa at each segment and visible protruding lesions were observed by magnifying NBI colonoscopy. The surface structure was classified into honeycomb-like, villous, or tortuous pattern. The grade of dysplasia was determined in the specimens obtained from protrusions and from flat mucosa. Main Outcome Measurements: The positive predictive value of conventional and NBI colonoscopy for the diagnosis of dysplasia. Results: A total of 296 sites (20 protruding lesions and 276 flat areas) were examined by NBI colonoscopy. The surface pattern was determined to be honeycomb like in 161 sites, villous in 85 sites, and tortuous in 50 sites. Five dysplastic lesions were detected in 3 patients. A patient had 3 dysplastic lesions and the other 2 had a dysplastic lesion each. The positive rate of dysplasia was higher in protrusions (2/20 sites, 10%) than in flat mucosa (3/276 sites, 1.1%, P = .038; however, correction for the multiple testing of data removes this significance). When the surface pattern was taken into account, the rate of positive dysplasia was higher in the tortuous pattern (4/50 sites, 8%) than in the honeycomb-like or villous patterns (1/246 sites, 0.4%, P = .003). Limitations: Uncontrolled study. Conclusions: The tortuous pattern determined by NBI colonoscopy may be a clue for the identification of dysplasia during surveillance for UC.