Value of magnifying endoscopy in classifying colorectal polyps based on vascular pattern

Background and study aims: Narrow-band imaging (NBI) has been developed as a new technique to differentiate tissue patterns in vivo. The aim of this study was to evaluate the diagnostic accuracy of NBI endoscopy with and without high magnification for the differentiation of neoplastic from non-neoplastic colorectal polyps. Patients and methods: Among 200 colorectal polyps from 131 patients, 100 lesions were classified according to vascular patterns by NBI endoscopy with high optical magnification and 100 lesions by high-definition endoscopy without high magnification. Additionally, the clarity of the vessel network was assessed. Histologic analysis was performed on all lesions. Results: NBI endoscopy with high magnification resulted in a sensitivity of 92.1% and a specificity of 89.2% for the differentiation of neoplastic versus non-neoplastic lesions. This performance was statistically comparable to high-definition NBI endoscopy without high magnification, which showed a sensitivity of 87.9% and specificity of 90.5%. However, vessel network was significantly better visualized by NBI endoscopy with optical magnification compared with high-definition NBI endoscopy without high magnification. In comparison with NBI endoscopy, white-light endoscopy, with or without magnification, resulted in inferior discrimination between neoplastic and non-neoplastic polyps. Conclusion: The results demonstrate that the superior visibility of capillary vessels by the NBI technique allows the evaluation of colorectal lesions based on the vascular patterns with high diagnostic accuracy. In clinical routine, high-definition NBI endoscopy without high magnification may be used to sufficiently predict colorectal polyp histology, and high magnification can additionally facilitate visualization of vascular networks.