Comparison of the Diagnostic Usefulness of Conventional Magnification and Near-focus Methods with Narrow-band Imaging for Gastric Epithelial Tumors

Abstract

Background/Aims: Dual-focus two-stage optical lens technology has been introduced recently. In near-focus mode (NFM), endoscopists can easily examine the mucosal tissue and capillary networks. This study compared the magnified images obtained using NFM and the conventional magnification method (CMM) under narrow-band imaging in patients with gastric epithelial tumors. Materials and Methods: An experienced endoscopist performed endoscopy using NFM and CMM in patients with gastric epithelial tumors. We studied 40 images from 40 endoscopy sessions in 20 selected patients. Ten endoscopists rated the image quality independently on a 5-point Likert scale (from poor=1 to excellent=5) in terms of microsurface structure, microvascular structure, and the demarcation line. Results: The gastric epithelial tumors comprised 10 cases of early gastric cancer, 2 of high-grade dysplasia, and 8 of low-grade dysplasia. The median number of magnified images for each method was 11. The mean observation time (±SD) for magnification was 99.9±64.1 s in NFM and 91.5±64.6 s in CMM (P=0.54). The image quality score for the microsurface structure was higher with NFM than CMM (4.09±0.39 vs. 3.73±0.40, P=0.015), while that for microvascular structure was lower with NFM than in CMM (3.53±0.45 vs. 4.29±0.45, P=0.001). Conclusions: Magnification using NFM provides higher-quality images of the microsurface structure, although its optical zoom is limited compared with CMM. Since NFM can obtain magnified images easily by pushing a button on the scope, it is useful for evaluating gastric epithelial tumors.