PET-CT examination is helpful for gastric cancer, but usually cannot confirm the diagnosis of gastric cancer. PET-CT is a highly sensitive, accurate and non-invasive examination method, which has the value of early detection and early diagnosis for many diseases, especially common malignant tumors and other diseases, and can detect early gastric cancer and metastases, and some patients with gastric cancer have PET-CT examination The effect is very good. Generally, PET-CT can detect part of gastric cancer, but some gastric cancers cannot be detected, such as indolent cell carcinoma, i.e. mucinous hypofractionated adenocarcinoma, which will be less sensitive with 18F-FDG injection and may have false negative. However, PET-CT has the function of CT and will see the thickening of the stomach wall, which will then alert the clinician that it may be a patient with gastric cancer. PET-CT can help doctors to diagnose gastric cancer, but further gastroscopy is needed to confirm the condition.