Ordinary CT plain scan cannot detect some smaller lesions, such as ulcerative colitis CT is not able to diagnose, only endoscopy can be performed. If there is a swelling in the intestine, CT intestinal cavity organ imaging can be performed. After the intestine is cleaned in advance, CT three-dimensional reconstruction is performed to show the three-dimensional structure of the intestine, which can not only see inside the cavity, but also outside the cavity, and see the tumor situation, which can show the intestinal swelling, that is, morphological changes occur, and the swelling can be shown by CT when it reaches a certain size. Colon masses are easier to show, however, the small intestine is particularly long, 5-6m in length, and overlap each other, so smaller lesions in the small intestine are more difficult to detect.