There are lack of endoscopic criteria for diagnosing Helicobacter pylori (H. pylori) infection by conventional white light imaging (WLI). Linked color imaging (LCI) is a newly developed endoscopy technique, which can diagnose mucosal lesions and H. pylori infection by enhancing color contrast of the mucosa. The aim of the study is to investigate the ability of LCI for diagnosing H. pylori infection compared with WLI.

Helicobacter pylori (H. pylori) is one of the most common chronic bacterial infections in man. And it is the causative factor for peptic ulcer and regarded as a class I carcinogen for gastric adenocarcinoma. Therefore, accurate detection of infection is crucial for devising proper eradication regimens and preventing the more severe GI complications. Detection of H. pylori in the gastric mucosa can be performed via (1) direct detection of the bacterium; culture, histology and polymerase chain reaction or (2) indirect detection of its enzymatic products particularly urease and serum H. pylori-specific antibody examinations. The direct detection methods are complicated and time-consuming. While the indirect detection methods are less accurate. With the wide use of endoscopy, diagnosis of H. pylori infection by endoscopy should be more accurate and easily available. However, there are still lack of endoscopic criteria for diagnosing H. pylori infection by conventional white light imaging (WLI), which correlates poorly with histopathological findings of H. pylori-induced gastritis . The newly modified LCI system (FUJIFILM Co.) can obtain clear and bright endoscopic images by using short-wavelength narrow-band laser light combined with white laser light. LCI technique can enhance the color of the endoscopic images by digital processing, which makes red regions seem redder and white regions seem whiter. Therefore, LCI may facilitate the detection of certain kinds of gastric lesions. As the common thinking, H. pylori-associated gastritis regions are redder than normal mucosa under WLI because of hyperemia following inflammation. And such redness can be enhanced by LCI. However, there is no criterion for this estimating. Red, green and blue (RGB) color model is a basic component system of the hue, of which each color is a composition of different proportions. Thus, the color obtained by endoscopic images can be quantified by RGB model. The study aimed at comparing the ability of WLI and LCI for diagnosing H. pylori infection by using RGB color model and investigating objective and quantifiable endoscopic criteria for predicting H. pylori infection.

Inclusion Criteria:

• People who undergo esophagogastroduodenoscopy for possible upper gastrointestinal disease

Exclusion Criteria:

• Patients who have taken proton pump inhibitor, antibiotics, non-steroidal anti-inflammatory drugs, bismuth agent, H2-receptor inhibitor and medicines that can affect the test of H. pylori infection in a month
• Patients with severe systematic disorders
• Patients with accurate gastrointestinal bleeding in a week
• Patients with histories of gastric surgery
• Pregnant and lactating women
• Patients with poor coagulation function
• Patients diagnosed with gastric cancer

People who undergo esophagogastroduodenoscopy in the First People's Hospital of Kashgar Region. All patients provided written informed consents to undergo esophagogastroduodenoscopy and participate in this study.