Electronic chromoendoscopy in Barrett's oesophagus using narrow band imaging: A study to validate mucosal morphology findings and inter/intraobserver agreement

Background & Aim: High Resolution Magnification Endoscopy (HRME) with Narrow Band Imaging (NBI) improves visualization of mucosal surface without the need for dye spray (Electronic Chromoendoscopy) 1. Our aim was to validate the mucosal morphology findings and inter/intra observer agreement in detecting cardia mucosa (CM), Specialized Intestinal Metaplasia (SIM), dysplasia (D) and early cancer (EC) in Barrett's Esophagus (BE). Methods: After inspecting BE in white light overview mode, NBI endoscopy in overview and magnification mode every 1-2 cm was performed by four expert endoscopists (RS, GKA, KY, KR) and a minimum of one biopsy taken from each quadrant imaged. Magnified NBI endoscopic findings were classified as: A) Round pits with regular microvasculature, B) Villous/Ridge pits with regular microvasculature, C) Absent pits with regular microvasculature and D) Irregular pits with irregular microvasculature. The endoscopic findings and the corresponding biopsies were recorded and blinded histopathological analysis performed. The sensitivity, specificity, and predictive values of the various patterns for the prediction of CM, SIM and D/EC were then calculated. Reproducibility of this classification was assessed by four non-NBI expert endoscopists (HK, PF, AS, KG). Two hundred and ten digital images of each pre-biopsy specimen were selected and the predominant pattern agreed upon by the expert endoscopists. Forty of the images were first shown as a reference guide followed by the remaining images which were graded based on the above classification. This was repeated after one week, with the same images but in a different order. Results: One hundred patients (71 males, mean age 61.7, mean length 4.3 cm, 890 biopsy specimens) were recruited. The sensitivity, specificity, positive and negative predictive values for round pits (type A) corresponding to CM was 97%, 100%, 100%, and 100% respectively; 2) types B-C for the prediction of SIM were 100%, 60%, 86% and 100% respectively and 3) type D for the prediction of HGD/EC was 94%, 100%, 90%, and 100% respectively. The mean kappa value for inter-observer agreement in assessing the various patterns were 0.711 (SD-0.042) and the intra-observer agreement was 0.869 (SD-0.031). Conclusion: HRME with NBI can clearly visualize the mucosal morphology in BE without dye spray. It has a high level of inter and intra observer agreement, further demonstrating its potential to be useful in routine clinical practice.1. Anagnostopoulos GK et al. High Resolution Magnification Endoscopy with Narrow Band Imaging in Barrett's oesophagus. Gut 2006;55:A105.