Usefulness of third-generation narrow band imaging and texture and color enhancement imaging in improving visibility of superficial early gastric cancer: A study using color difference

Objectives: Overlooking early gastric cancer (EGC) during endoscopy is an issue to be resolved. Image-enhanced endoscopy is expected to improve EGC detection. This study investigated the usefulness of third-generation narrow band imaging (3G-NBI) and texture and color enhancement imaging (TXI) in improving the visibility of EGC using the color difference between EGC and its surrounding gastric mucosa. Methods: In this retrospective observational study, we examined 51 superficial EGCs that underwent endoscopic submucosal dissection and were observed by all three methods: 3G-NBI, TXI, and white light imaging (WLI). The primary endpoint was to compare the color difference of each method. For each EGC, we prepared one non-magnifying image for each method so that the location and size of the lesion in each image were the same. The L*a*b* color space was used to evaluate the color values. When the color values of the cancerous lesion and its surrounding mucosa were (L*(c), a*(c), b*(c)) and (L*(s), a*(s), b*(s)), respectively, the color difference was defined to be [(L*(c)-L*(s))(2)+(a*(c)-a*(s))(2)+(b*(c)-b*(s))(2)](1/2). Results: The median color difference was 9.2 (interquartile range, 5.3-15.7) in WLI, 13.5 (interquartile range, 9.4-19.5) in 3G-NBI, and 15.3 (interquartile range, 9.1-22.1) in TXI. Statistically, the color difference was significantly larger in 3G-NBI than in WLI (p < 0.001) and TXI compared with WLI (p < 0.001). However, there was no significant difference between 3G-NBI and TXI (p = 0.330). Conclusions: Regarding color difference, both 3G-NBI and TXI were estimated to be more useful than WLI in improving the visibility of superficial EGC.