Early detection of gastric intestinal metaplasia (GIM) intraepithelial neoplasia (IN), and gastric cancer are essential to improve patients' outcomes. This study aims to compare the diagnostic yield of GIM, IN and early gastric cancer (EGC) by iScan combined probe-based confocal laser endomicroscopy (pCLE) and iScan alone.

Inclusion Criteria:

• aged between 18 and 80;
• patients with previous pathologic diagnosis of atrophic gastritis, gastric intestinal metaplasia, and low-grade intraepithelial neoplasia;
• agree to give written informed consent.

Exclusion Criteria:

• Patients with gastrectomy, acute GI bleeding, and known gastric neoplasia;
• Patients under conditions unsuitable for performing CLE including coagulopathy (prothrombin time <50% of control, partial thromboplastin time >50 s), impaired renal function (creatinine level >1.2 mg/dL), pregnancy or breastfeeding, and known allergy to fluorescein sodium;
• Inability to provide informed consent