Interobserver Agreement in Using Magnifying Narrow Band Imaging System

cancer is the second most common cancer in Ko-rea, but mortality due to gastric cancer is decreasing. This phenomenon is probably a result of the National Cancer Screening Program, which provides biennial endoscopic screening and facilitates early detection of gastric cancer that can be cured by endoscopic treatment or minimally invasive surgery. 1 During the endoscopic screening, precancerous lesions including low-grade adenomas are commonly found, which can be differentiated from high-grade dysplasia or invasive carcinomas by histological evaluation after collecting a biopsy specimen. However, even a biopsy-confirmed low-grade ad-enoma can be identified as a high-grade dysplasia or carcino-ma using full pathological evaluation after endoscopic resec-tion. 2 A low-grade adenoma usually can be treated using a less invasive modality such as argon plasma coagulation in the outpatient setting. 3 Alternatively, low-grade adenomas can be followed up without any invasive treatment in elderly patients with comorbid conditions including cardiovascular disease that need antiplatelet or anticoagulant therapy, which imposes a higher risk of postprocedural bleeding after endoscopic re-section. 4 Using a narrow band imaging (NBI) system, endoscopists can evaluate the mucosal microvascular (MV) architecture and microsurface (MS) structure as well as demarcation lines (DL) between the lesion and the surrounding background mucosa. 5 NBI is useful for the diagnosis of upper gastrointes-tinal diseases including superficial esophageal squamous cell carcinomas (SESCC), 6 Barrett esophagus, 7 chronic gastritis associated with Helicobacter pylori infection, 8 or early gastric cancers (EGCs). 9 Magnifying NBI (M-NBI) allows endosco-pists to observe detailed morphological features using the aforementioned criteria, which can lead to histologic diagnosis that can be used to differentiate carcinomas, from benign lesions, including adenomas. A recent prospective study using real-time analysis suggested that M-NBI in combination with conventional white light imaging (C-WLI) was used to identify the small, depressed type of EGCs with >95% accuracy , sensitivity, and specificity. 13 Identification of the DL and then subsequent inspection of an irregular MV pattern diagnosed using DL was an efficient strategy to identify the small, depressed type of EGC. 14 A consensus report about the role of NBI in the Asia Pacific region for the diagnosis of early-stage esophagogastric cancer was published recently. 5 For SESCC, most of the expert panels agreed that NBI is useful for detecting and determining the extent of SESCC. M-NBI can be very useful for determining the tumor depth of SESCC. NBI is not useful for detecting EGC, as the view of NBI …