Intra and interobserver agreement of narrow band imaging for the detection of head and neck tumors

Background Narrow band imaging (NBI) in combination with white light endoscopy (WLE) has improved the accuracy for the diagnosis and follow-up of head and neck carcinomas by identifying changes in the vascular patterns of the mucosa. However, NBI evaluation is explorer-dependent and may be influenced by the learning curve. The aim of this study is to assess the intra and interobserver agreement of NBI and WLE at the office, under local anaesthesia, by either experienced or non-experienced observers. Methods Eighty-seven images of head and neck lesions were routinely collected under WLE and NBI. A group of three experienced otolaryngologists and three medical students assessed the images after a brief training. No additional patient information was provided. The same protocol was repeated after three weeks. Intra and interobserver agreement were calculated with the kappa index. Results NBI intraobserver agreement was substantial (kappa = 0.62) and better than with WLE alone, which was moderate (kappa = 0.57) in both groups. Interobserver agreement was moderate with WLE (kappa = 0.58) and substantial with NBI (kappa = 0.63). Both groups improved intraobserver and interobserver agreement with the implementation of NBI. Conclusions Intra and interobserver agreement with NBI for the evaluation of head and neck lesions are substantial, and improve the results of WLE alone in both, professionals and trainees.