© Georg Thieme Verlag KG Stuttgart · New York
Reflux and Barrett’s disease
04 December 2008 (eFirst)
Narrow-band imaging with magnification in Barrett’s esophagus: validation of a simplified grading system of mucosal morphology patterns against histology (Singh et al., Endoscopy 2008 )
Several pilot studies have been published over the past 2 years with regard to the use of newly available imaging techniques, in particular narrow band imaging (NBI). In this prospective study in 109 patients with Barrett’s esophagus, Singh et al. describe a simplified NBI classification to predict final histology. In contrast to the previously reported Kara classification , the vascular and mucosal assessment are combined into four patterns: Type A, round pits and regular microvasculature; Type B, villous/ridge pits with regular microvasculature; Type C, absent pits and regular microvasculature; and Type D, distorted pit with irregular microvasculature. The diagnostic accuracy of the NBI-zoom images in predicting the final histology was high (87.9 %). Type A, Type B or C, and type D were predictive of columnar epithelium without intestinal metaplasia, intestinal metaplasia, and high-grade intraepithelial neoplasia (HGIN), respectively. Moreover, the inter- and intraobserver agreement was very good.
These findings correlated well with the data on acetic acid-assisted chromoendoscopy, on which the new proposed classification is based . This study illustrates the fact that initially rather complicated classification schemes   can be simplified to a categorical classification that is clinically useful. Some aspects of this interesting paper need to be taken into account. The endoscopic red-green-blue system (XCV-260HP processor with Q240Z endoscope) that was used in the study is not readily available in most European and American practices. The study was performed in a tertiary referral center that has excellent experience in advanced imaging. The proportion of high-grade dysplasia (13 %) is higher than in the general Barrett’s surveillance population. The fact that some patients were referred for work-up of previously diagnosed dysplasia may influence the efficacy of diagnosing dysplasia. However, the simplified classification scheme looks promising and easily applicable, particularly as nonexpert NBI readers also displayed a good inter- and intraobserver agreement. However, the accuracy of NBI imaging with or without zoom in a general surveillance population remains to be established. Although the Kara classification  was perceived by the authors to be tedious and difficult to apply in routine practice, recent data suggest that even without magnification, NBI-directed biopsies – based on the Kara classification – can detect more dysplastic lesions compared with normal white light endoscopy and random biopsies . Again, in the latter paper the prevalence of neoplasia in the study population was as high as 57 %. Further studies are therefore needed to establish the performance of NBI and the different classification schemes in a general surveillance program.