Esophageal NBl without abnormal microstructure and microvessels means that there are no abnormal blood vessels and other tissue proliferation under the esophageal mucosa. NBl, or endoscopic narrow-band imaging, is a special electronic staining technique in gastroscopy that enhances the images of blood vessels in the GI mucosa. Esophageal NBl refers to the examination of the esophagus using endoscopic narrow-band imaging technology, which is helpful in identifying microscopic lesions such as early esophageal cancer. NBl is an emerging endoscopic technique that utilizes a narrow-band filter to filter out the red light band emitted by the endoscopic light source, leaving only the green and blue narrow-band light waves of 540nm and 415nm wavelengths. Due to the optical properties of hemoglobin in submucosal blood vessels, i.e., strong absorption of blue and green light, the contrast and clarity of the mucosal epithelium and submucosal blood vessels can be increased. Esophageal NBl can enhance the color contrast of blood vessels and mucosa in endoscopic images, which not only can accurately observe the structure of esophageal mucosal epithelial glands, but also can enucleate esophageal epithelial microvessel morphology, which can help to identify lesions accompanied by microvascular alterations, such as esophageal cancer.