Comparison of magnified pit pattern interpretation with narrow band imaging versus chromoendoscopy for diminutive colonic polyps: a pilot study

Background: Chromoendoscopy can accurately differentiate neoplastic from nonneoplastic polyps in the colon. Narrow band imaging (NBI) has been described as "electronic chromoendoscopy," but it is unclear whether pit patterns seen with chromoendoscopy are identical to those with NBI Objective: Pilot study to compare features of diminutive polyps assessed with magnification NBI and chromoendoscopy. Design: Prospective polyp series. Setting: Single tertiary referral center in the United Kingdom. Patients: Twenty patients seen for routine colonoscopy. Intervention: Digital images of each polyp recorded with NBI and chromoendoscopy were subsequently assessed as single images in a random order and as paired polyp images by experienced European- and Japanese-trained endoscopists. Main Outcome Measurements: Pit pattern (Kudo classification); vascular pattern intensity (weak, normal, strong); predicted histology; pit pattern and vessel network clarity (scale 1-3, 1 poor, 3 excellent). Results: A total of 33 polyps <= 6 mm were assessed. Chromoendoscopic and NBI pit patterns were different for 12 and 20 of 33 polyps (Japanese and European, respectively), combined K 0.23, P < .001 compared with published intraobsever variation. Sensitivity, specificity, and accuracy for neoplasia were comparable for chromoendoscopic and NBI pit patterns and vascular pattern intensity for both observers. Vessel network clarity was better with NBI P < .001 (both), as was pit pattern clarity, P = .04 (European). Limitations: Small sample size; pilot study Conclusions: Pit patterns were not always identical with NBI and chromoendoscopy. The Kudo classification may need to be modified and revalidated before it can be used with confidence with NBI. Vascular pattern intensity, a simple color change, appears as accurate as pit pattern.