The early stage of digestive tract disease is usually endoscopic because early lesions are in the mucosa as well as submucosa and cannot be examined by CT. When the swelling grows to a certain extent, the lesion can be shown by CT inside and outside the intestine. If the swelling grows outward and cannot be seen by endoscopy, CT can clearly see the three-dimensional structure of the swelling and the surrounding relationship for further differentiation. When the digestive tract swelling reaches the middle and late stages, CT (especially enhanced CT) can clarify the lesion site, size, relationship with the surrounding area, and the presence of enlarged lymph nodes, which can make a clear diagnosis.