Value of magnifying chromoendoscopy and narrow band imaging (NBI) in classifying colorectal polyps: a prospective controlled study

Background and study aims: Chromoendoscopy in combination with magnifying endoscopy is useful in distinguishing neoplastic from non-neoplastic colorectal polyps. Narrow band imaging (NBI) has been developed as a new technique to differentiate tissue patterns in vivo. The aim of the present study was to directly compare the diagnostic values of chromoendoscopy and NBI for the differentiation of neoplastic from non-neoplastic colorectal polyps.

Patients and methods: In total, 200 colorectal polyps from 99 patients were distributed in a 1 : 1 ratio in order to analyze the surface according to the pit pattern classification and vascular patterns by either magnifying chromoendoscopy or NBI magnification. Histologic analysis was performed on all lesions.

Results: Using the Kudo classification of mucosal patterns, NBI with magnification resulted in a sensitivity of 90.5 % and a specificity of 89.2 % for the differentiation of neoplastic vs. non-neoplastic lesions. This performance was comparable to magnifying chromoendoscopy with a sensitivity of 91.7 % and a specificity of 90 %, respectively. Using vascular patterns for differentiation, NBI with magnification correctly identified 93.7 % of neoplastic polyps and 89.2 % of non-neoplastic colorectal lesions, whereas magnifying chromoendoscopy had a specificity of 95 % but a sensitivity of only 66.7 %.

Conclusion: NBI in combination with magnifying endoscopy is a promising tool for the differentiation of neoplastic from non-neoplastic colorectal polyps in vivo without the necessity of using dye. The detection of capillary vessels with NBI allows the evaluation of colorectal lesions based on the vascular patterns with high diagnostic accuracy.

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