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.