1.Zonal anatomy of the stomach (1)Gastric fundus: the right side of the fundus is almost completely occupied by the liver. (2) Cardia area: the gastric cavity is further enlarged and shifted to the left posterior side. The cardia is flared and the local gastric wall is significantly thicker than other parts of the same layer, sometimes forming a pseudomass. The location of this zone is more fixed and is at the same level as the venous ligamentous cleft of the liver. (3) Middle and upper gastric body: the left posterior side of the gastric cavity is the greater curvature of the gastric body, the right side is the lesser curvature of the gastric body, and the greater and lesser curvatures are roughly quadrate with the anterior and posterior walls. The right side of the gastric cavity is the hepatogastric ligament, and the left gastric artery, which travels in an arc from the left posterior to the right along the gastric lesser curvature, can be seen in the enhanced scan within the hepatogastric ligament. The left posterior lateral aspect of the gastric cavity is the splenogastric ligament, and the short gastric artery distributed within the splenogastric ligament along the greater curvature of the stomach can be seen on enhancement scans. This level is roughly equivalent to the level of the hepatic hilum. (4) Middle and lower part of the gastric body: the gastric cavity shifts to the right anteriorly, with the greater curvature of the gastric body on the left and the lesser curvature on the right, and the anterior and left sides of the gastric wall are often close to the abdominal wall. At the level close to the lower part of the body stomach sometimes appears another smaller gastric cavity on its right side, which is the pyloric portion of the gastric sinus, with its medial (left) edge on the side of the small curvature of the gastric sinus and the anterolateral edge on the side of the large curvature of the gastric sinus. The section of the gastric sinus gradually expands downward and approaches the body part of the stomach. (5) Gastric horn notch: It appears as a thin linear soft tissue density shadow with similar thickness to the gastric wall that travels in the anterior-posterior direction. The stomach is divided into two cavities by the gastric angle, with the gastric angle (lesser curvature) in the middle and the greater curvature on the outer side of the two cavities. (6) Below the angular notch (Zhang Xiaopeng): the gastric cavity is gourd-shaped or oval, the gastric horn and the lesser curvature disappear, and the greater curvature of the stomach is on both the left and right sides. The right side of the gastric sinus is the gallbladder, the left posterior part of the gastric sinus is adjacent to the head or neck of the pancreas, and the posterior part of the gastric sinus is the descending duodenum. (7) Lower pole of the stomach (Zhang Xiaopeng): the gastric cavity is in a small oval shape, near the anterior abdominal wall, below which is the gastrocolic ligament, and on the left and right sides are the colonic splenic flexure and colonic hepatic flexure, respectively. (8) Pylorus: located at the same level of the gastric horn or slightly above and below it. The distal end of the gastric sinus and the pylorus are more than mildly folded to the left posteriorly. When the long axis of the gastric sinus and duodenum is parallel to the scanning level, the tangential bit images of the gastric sinus, pylorus and duodenal bulb are visible. Note: Special gastric type (1) Bull’s-eye gastric: the stomach is close to horizontal alignment and basically travels in front of the pancreas, and the gastric sinus is more obviously folded posteriorly. Because the stomach is close to horizontal, most of the stomach body can be seen at the cardia level. The gastric angle is often incomplete because of the close horizontal alignment of the stomach, and the demarcation between the gastric body and the gastric sinus is not obvious. Due to the rotation of the gastric axis, the lesser curvature of the stomach is biased toward the posterior wall, the greater curvature of the stomach is biased toward the anterior wall, and the pylorus opens in the posterior direction. (2) Inactive type of stomach: the stomach body is elongated in the longitudinal direction, the lower and middle part of the stomach body is in parallel longitudinal alignment with the gastric sinus, the small curve of the gastric sinus is adjacent to the gastric wall of the small curve of the stomach body, and the gastric angle is obvious. The opening of the pylorus is upward. (3) Waterfall type stomach: the fundus of the stomach is folded backward obviously. The posterior wall of the junction of the gastric fundus and the gastric body can be seen in the concave cut. 2, the thickness of the gastric wall is generally considered normal gastric wall thickness below 5 mm, the body of the large curved side of the thinnest generally in the 3 mm or less. The gastric wall of the cardia is thicker and bulges into the gastric cavity, and the gastric wall of the anterior pyloric region of the gastric sinus is thicker. The gastric wall is limited to finger-like internal protrusion during spasmodic contraction. When the gastric wall is oblique or parallel to the scanning surface, the gastric wall may appear thickened artifactually. On the enhanced scan image, most of the gastric wall has a single-layer structure, and a few of them have a three-layer structure, with the inner and outer layers showing obvious high density and the middle layer a low density band, the inner layer roughly equivalent to the mucosal layer, the middle layer equivalent to the submucosal layer, and the outer layer the muscular layer and plasma membrane. To determine whether there is any abnormality in the gastric wall, one should look at the thickness of the gastric wall, and the other should look at whether there is abnormal strengthening of the gastric wall.