New Diagnostic Modality of Gastric Intestinal Metaplasia: Narrow Band Imaging System with Magnifying Endoscopy

Abstract

Intestinal metaplasia (IM) is regarded as one of the high-risk lesion for developing intestinal type gastric adenocarcinoma. IM usually appear in flat mucosa and have few morphologic changes. Therefore, its endoscopic diagnosis has high interobserver variability and a poor correlation with histological findings. By the narrow band imaging system with magnifying endoscopy (NBI-ME) in patients with history of endoscopic mucosal resection (EMR) for early gastric cancer (EGC), we found the discriminative endoscopic finding; blue fringe (BF). BF was defined as fine white-blue color fringing epithelial surface. In the present study, we investigated the diagnostic utility of BF for gastric intestinal metaplasia. Seventeen patients with a medical history of EMR for EGC and 17 age- and sex-matched patients having dyspeptic symptoms were participated in this study. After routine observation, NBI-ME was performed in the antrum at the maximum magnification (approximately ∼80) with Q-240Z (Olympus Medical System Co. Ltd.). BF was found in 15 of 17 (88%) patients with history of EMR for EGC, and 10 of 17 (59%) patients with dyspepsia (p = 0.059). Forty four biopsy sumples were taken from BF(+) and 44 from BF(−) mucosa, and the diagnostic accuracy for IM was evaluated in related to histological gold standard. NBI-ME images were taken before and after biopsy in order to assure the biopsy site and to provide reference images for agreement test. For diagnosis of IM by BF, sensitivity was 0.85 (95% CI: 0.75, 0.95), specificity was 0.90 (95% CI: 0.81, 0.99), positive predictive value was 0.91 (95% CI: 0.82, 0.99) and negative predictive value was 0.84 (95% CI: 0.73, 0.94), respectively. Kappa statistic for intraobserver agreement for presence of BF was 0.89 and for interobserver agreement was 0.74. BF found by NBI-ME is the valid and reproducible for endoscopic diagnosis of IM.