Introduction The gastroesophageal reflux disease is a common condition in the western world but less than half of patients present endoscopic abnormalities making a standard procedure unsuitable for diagnosis. reflux disease and Barrett’s esophagus are analyzed in several ways highlighting the findings and limitations. Conclusion NVP-BEZ235 The meaning of the narrow band imaging in the endoscopic diagnosis of reflux disease will be defined by large scale studies with different categories of patients including assessment of symptoms and response to treatment. Keywords: Gastroesophageal reflux disease Barrett’s esophagus Narrow band imaging High definition endoscopy Abstract Introdu??o A doen?a do refluxo gastroesofágico é KIAA0538 condi??o altamente prevalente no mundo ocidental porém em menos da metade dos pacientes há alguma altera??o endoscópica indicando que a endoscopia convencional n?o é o procedimento ideal para o diagnóstico da doen?a do refluxo gastroesofágico. A endoscopia com aparelhos de alta defini??o associado ao dispositivo “narrow band imaging” tem demonstrado aplica??o na diferencia??o de les?es benignas das malignas e a possibilidade de direcionar as biópsias permitindo diagnóstico e tratamento especialmente nos casos de cancer precoce. Método Esta revis?o descreve os princípios ópticos e sua influência na obten??o de imagens de vasos na mucosa através da “narrow band imaging”. Foram utilizados os descritores para pesquisa no PubMed e as publica??es analisadas em diversos aspectos com destaque para o “narrow band imaging” seus fundamentos aplica??es e limita??es. Conclus?o O significado do “narrow band imaging” no diagnóstico endoscópico da doen?a do refluxo gastroesofágico será definido por estudos em larga escala com categorias diferentes de pacientes incluindo avalia??o de sintomas e resposta ao tratamento. INTRODUCTION The upper gastrointestinal endoscopy has had major technological advancements in the past decades causing great impact on diagnostic accuracy. It started in the 60s with the optical fiber endoscope important tool to deal with several gastroenterological conditions. Twenty years after that conventional videoendoscopy appeared with improvements in both definition and image resolution which increased from 100 0 to 300 0 pixels. However identifying esophageal conditions by means of conventional videoendoscopy is limited to the presence of lesions in the mucosa such as plaques erosions ulcers or nodules. As a result the gastroesophageal reflux disease (GERD) which is a highly common condition in the western world presents abnormalities in the endoscopic exam in less than half of the patients with typical symptoms. Therefore the standard procedure is not very sensitive to diagnose it 19. In view of the need for more diagnostic accuracy high definition endoscopy coupled with narrow band imaging (NBI) was developed. It enables image resolution of one million pixels which increases the diagnostic accuracy in biopsy of several esophageal conditions. Narrow band imaging Its development was made available by Olympus Medical Systems in Japan. It was first reported by NVP-BEZ235 Sano et al.22 in 1999 and introduced in commercial scale in 2005. The NBI is an important advancement in endoscopy technology based on the physics principle that the penetration depth of light waves in the tissues is directly proportional to its size. Therefore the longest the wave the NVP-BEZ235 deeper the penetration in the tissues7. The use of spectral filters (red green and blue strips) of the NBI highlights the characteristics of the mucosa and vascular patterns of the esophagus stomach and colon with better definition when compared to the standard endoscopic exam. Two systems are currently available to use endoscopy with NBI. The sequential magnifying system with high resolution endoscope (GIF Z160) which enables optical magnification of up to 80 times and the “charged coupled device” system of the high definition device (high-definition television) – GIF H 180 which has digital zoom with magnifying potential from 1.2 to 1 1.5 times. This image magnification associated to the NBI improves diagnostic accuracy resulting from the detailed assessment of the pattern of capillary intrapapillary mucosa vessels. However the NBI has the disadvantage of a dark image which makes it impossible to identify abnormalities in the color and morphology of lesions when located far from the endoscope. Light and biotic principles Unlike conventional image processing the NBI highlights the image obtained through light filters. The light NVP-BEZ235 visible to the human eye is made up by a.