1.CT signs of gastric cancer (1) Localized gastric wall thickening and abnormal enhancement with uneven surface mucosa or ulcer or bulge; (2) Intraluminal mass, which can have various shapes; (3) Intraluminal ulcer and ring dike, the morphology of the ring dike is the key to distinguish Borrmann 2 and Borrmann 3 gastric cancer. (4) Stenosis of gastric lumen with rigid gastric wall. (5) Gross plasma membrane layer and unclear surrounding fatty gap. 2. Stomach cancer typing and CT signs Early gastric cancer can be divided into: type I augmented type; type II flat type; type III depressed type. The CT signs of early gastric cancer are local gastric wall thickening and abnormal enhancement, uneven surface mucosa or ulceration or bulge. Progressive gastric cancer can be divided into Borrmann type 1; Borrmann type 2; Borrmann type 3; Borrmann type 4. Borrmann type 1 (mass-like) shows intracavitary masses in the form of giant masses, mycelium, cauliflower, nodules, polyps, etc., with uneven surface, clear boundary between the base and the surrounding gastric wall, and cut marks can be seen at the edge. Borrmann type 2 (confined ulcer type) shows intra-luminal ulcer with clear demarcation between the peripheral ring dike and the surrounding gastric wall.Borrmann type 3 (infiltrative ulcer type) also shows intra-luminal ulcer, but the peripheral ring dike is not clearly demarcated from the surrounding gastric wall, and the outer edge is slope like invasion.Borrmann type 4 (diffuse infiltrative type) shows thickening of the gastric wall, narrowing of the gastric lumen, lumen The shape is irregular and the mucosal surface is not smooth.