Enhanced CT refers to the rapid injection of iodine-containing contrast agent through a vein, usually the elbow vein of the upper arm or a thicker vein on the back of the hand, within a certain period of time. It is used for the diagnosis and differential diagnosis of the disease, with the aim of improving the accuracy of the diagnosis of the disease. Precautions are as follows: 1. You cannot eat but can drink water, and fast 4-6 hours before the examination; 2. Patients who have had allergic reactions to iodine enhanced CT before are not recommended to do enhanced CT again; 3. Patients with asthma should also do enhanced CT with caution; 4. A report card with normal kidney function test is required.