Endoscopy plays a pivotal role in the management (diagnosis and treatment) of Barrett's related neoplasia. The standard endoscopy is generally done under white light, which is known to be imperfect in detecting early neoplastic lesion. Narrow band imaging (NBI) improves definition of the superficial morphology and vasculature of GI mucosa. Some studies have shown the potential to improve diagnostic accuracy and reduce the number of biopsies required for Barrett's related neoplasia. This can ultimately improve the cost-effectiveness of endoscopic surveillance. The ability to discriminate between healthy and diseased tissue also makes NBI a useful technique for the delineation of lesions to treat with endoscopic mucosal resection (EMR). However not all studies provide evidence of diagnostic utility. Also the majority of these studies have been conducted by expert endoscopists, which makes the results difficult to extend to general endoscopy practice. The limited number of Barrett's specialists in certain areas of the country validates the need for a study to investigate whether there is an objective improvement in detection and delineation of Barrett's neoplastic lesions by less experienced observers. The aim of this study was to determine the utility of non-magnified NBI in non-expert identification of lesions as compared to expert endoscopists as well as the inter-observer agreement among endoscopists on WLE and NBI.

Matched non-magnified white-light endoscopy (WLE) and narrow band imaging (NBI) images of Barrett's oesophagus with and without lesions from the same level will be obtained prospectively. Lesions will be delineated by 3 expert endoscopists and the overlap between all delineations for each image, regarded as the "sweet spot", will be used as the gold standard. The images will then be assessed by a group of non-expert endoscopists (trainees and nurse endoscopists) as well as senior endoscopists with no interest in Barrett's. First, white light images will be assessed, followed by a wash-out period and then NBI. Assessments will be carried out using a computer application designed in MATLAB. Observers will be also asked to complete the following 1) Paris classification of lesion 2) delineation of the lesion on the screen 3) rate the ability to delineate the lesion for each of the two respective imaging modalities (using a Visual analog scale (VAS score 1-10), 4) choice a single point for virtual diagnostic biopsy. Thus, the quantitative interobserver agreement of the delineations for WLE and NBI will be calculated. VAS scores for the ability to delineate the lesion will be compared between WLE and NBI. Rate of inclusion of the biopsy point in the sweet spot on WLE and NBI will be compared.

Inclusion Criteria:

• Diagnosed with dysplastic or non-dysplastic BO at least C1 or M2 in length

Exclusion Criteria:

• Reflux oesophagitis (Los Angeles grade ≥C);

Patients undergoing surveillance for Barrett's oesophagus or work up for Barrett's related neoplasia