Utility of Japan Narrow Band Imaging Expert Team Classification Using Narrow Band Imaging for Evaluation of Colonic Polyps

Abstract

Abstract Background Narrow band imaging (NBI) is an advanced endoscopic imaging technique that enhances visualization of the mucosal surface and is used as a screening tool for colonic polyps. Its usefulness is currently explored to a lesser extent in India. So, we assessed the utility of Japan NBI Expert Team (JNET) classification for characterization of colorectal polyps. Methods A prospective observational study was performed from January 2018 to June 2019 of patients undergoing colonoscopy at a tertiary care hospital. NBI image of polyps was captured followed by either polypectomy/biopsy. Histopathology results were correlated with the pattern revealed by NBI on polyps using the JNET classification. Results A total of 80 patients, 61(76.25%) male with a mean (standard deviation [SD]) age of 58.41 ± 14.59 years were included. Out of the 90 lesions, 23 (25.5%) had type-1 pattern, 45 (50%) had 2A, 13 (14.4%) had 2B, and 9 (10%) had type-3 pattern. On histopathology, majority 51 (59.3%) were found to be adenomatous with low-grade intramucosal neoplasia. When correlating our results with JNET category type 1 and hyperplastic polyps, the sensitivity was 90%, specificity was 97%, negative predictive value was 97%, positive predictive value was 90%, and diagnostic accuracy was 96%. Correlating type 2A and low-grade intramucosal neoplasia had results of 78, 87, 76, 90, and 82%, respectively. Correlating type 2B and high-grade intramucosal neoplasia had results of 83, 90, 99, 38, and 90%, respectively. Correlating type 3 and deep submucosal cancer had results of 88, 98, 99, 78, and 97%, respectively. Conclusion NBI shows excellent probability to exclude carcinoma possibilities based on the changes in colonic mucosal features. Owing to slightly lower sensitivity for type 2B, it needs additional investigation using pit pattern diagnosis. We demonstrated the high-diagnostic performance of NBI in making an accurate diagnosis of early colorectal cancers in colonoscopy. Further refinement in the NBI technology might add to the current evidence for characterization of polyps.