Narrow band imaging in gastroesophageal reflux disease and Barrett's esophagus.

Narrow Band Imaging (NBI), developed by Olympus Medical Systems (Olympus, Japan), is a new and well-recognized advance in endoscopic imaging. Although conventional white-light endoscopy uses the entire spectrum of visible light (400 nm to 700 nm) to examine tissue, the NBI system uses optic filters to isolate two specific bands of light: 415 nm blue and 540 nm green (1–4). By isolating these two bands of light and taking into account their absorptive and reflective properties on the mucosal surface, an image that enhances visualization of superficial mucosal and vascular structures is created. The highlight of NBI endoscopy is the proposed ability to predict pathology in real-time based on the mucosal and vascular changes detected. NBI has been investigated for use as a diagnostic modality in a variety of lesions in the gastrointestinal, respiratory and genitourinary tract (4–6). Conveniently, the NBI mode on an endoscope can be activated with the depression of a switch similar to taking a picture. Dr Robert Enns NBI, often referred to as ‘digital chromoendoscopy’, was developed as an alternative method of obtaining visual enhancement of tissue similar to that seen in chromoendoscopy – a procedure that uses the absorptive properties of various dyes, such as indigo carmine, rather than optical filters (1–4). Although much research concerning the use of chromoendoscopy has been conducted, its widespread use has not been adopted for various reasons including the increased time involved with the procedure and the lack of training (ie, many training centres do not use it regularly). In the January 2009 issue of The Canadian Journal of Gastroenterology, we discussed the role of NBI for the detection of neoplastic lesions of the lower gastrointestinal tract; specifically its utility in the diagnosis of adenomatous polyps and dysplasia in ulcerative colitis, hereditary nonpolyposis colorectal cancer and screening colonoscopy. The purpose of the present paper is to review the use of NBI endoscopy as a diagnostic modality for lesions of the upper gastrointestinal tract with particular emphasis on Barrett’s esophagus (BE).