Usage of Narrow Band Imaging System in the Colorectum

Kashida, Hiroshi

Abstract

Narrow Band Imaging (NBI) is a novel technique that uses spectral narrow-band optical filters instead of the full spectrum of white light. As a result, superficial fine vessels and deeper thick vessels are demonstrated as brownish lines and greenish lines, respectively. This function enables detailed inspection of microvasculature of various kinds of gastrointestinal pathologies. Here is review of literature and present status of NBI in the endoscopic examination of colorectal lesions. There have been only a few papers concerning the usefulness of NBI for detecting colorectal polyps. The results were somewhat conflicting, but it seems that NBI has a possibility to enable beginners to detect polyps more easily. As for ability for tissue characterization, many studies demonstrated that NBI is useful for differentiating neoplasia from nonneoplasia; with or without magnification. Findings of magnified view with NBI are mainly analyzed in Japan and there are four major classifications of vascular patterns. Regardless of the classification system used, NBI was useful for differentiating between massively invasive cancers and less invasive lesions. Some authors have reported on their trial of utilizing NBI for the detection of ulcerative clolitis-related neoplasia. These reports suggest that NBI may render invisible endoscopic findings more visible without any dye solution, but the efficacy of NBI has not been proven yet. There is some possibility that NBI may replace chromoendoscopy, but a further study is needed to clarify which is more suitable, chromoendoscopy or NBI in the diagnosis of colorectal lesions.