Usefulness of Narrow Band Imaging for the Diagnosis of Early Gastric Cancer: A Comparison Study with Conventional Endoscopy

Abstract

Usefulness of Narrow Band Imaging for the Diagnosis of Early Gastric Cancer: A Comparison Study with Conventional Endoscopy Hirohisa Machida, Kazuhide Higuchi, Masahiko Tabuchi, Satoshi Sugimori, Natsuhiko Kameda, Tomoko Wada, Hirotoshi Okazaki, Masatsugu Shiba, Toshio Watanabe, Kazunari Tominaga, Yasuhiro Fujiwara, Tetsuo Arakawa Background and Study Aims: Importance of angiogenesis in the development of malignant disease is well recognized, and the morphologic changes in microvascular structure were useful in the diagnosis of early gastric cancer. The NBI system (NBI) is based on narrowing the bandwidth of spectral transmittance of optical filters, enables to clearly observe the surface and microvascular structure in the superficial lesion. The aim of this study is to evaluate the usefulness of NBI for the diagnosis of early gastric cancer. Patients and Methods: Twenty patients with 22 lesions underwent endoscopic examination for superficial gastric lesion. All lesions, which were confirmed as early gastric cancer, were investigated twice each by magnifying endoscopy with and without NBI, and recorded on digital video. Endoscopic evaluation focused on two findings which are specific for early gastric cancer, 1) irregular microvascular pattern (IMP), defined as irregularity of subepithelial microvascular structure, and 2) demarcation line (DL), defined as the border line between normal mucosa and cancerous lesion. Two endoscopists (one was well-experienced for NBI and magnifying endoscopy and another had no experience for both) assessed the digital video, and assigned to 3 grades for delineation of IMP and DL, visible or not for detectability of DL, according to the quality of visualization. These findings of NBI endoscopy were compared with those of conventional magnifying endoscopy. Results: For the IMP delineation, NBI endoscopy was superior to conventional endoscopy (p ! 0.0001). In NBI endoscopy, IMP was visualized clearly and differentiated easily from collecting venules of normal mucosa. The DL detectability was similar among NBI and conventional endoscopy (87.9% vs. 81.0%), but NBI endoscopy was superior to conventional endoscopy for the DL delineation (p ! 0.0001), resulting in the margin of the lesion being clear. With conventional endoscopy, well-experienced endoscopist was superior to not-experienced endoscopist in identifying the DL delineation, but it became to be similar with NBI endoscopy without significant difference. Conclusions: NBI endoscopy visualized the surface and microvascular structure evident, therefore it might be useful for the diagnosis of early gastric cancer, independent of experience. To estimate the usefulness using the NBI system for the diagnosis of early gastric cancer, randomized control trials should be conducted in the future.