Enhanced CT can view the portal vein. The principle of enhanced CT is to inject the contrast agent into the vein, the contrast agent flows with the direction of blood circulation, so that the blood flow of each organ and lesion tissue can be seen, the contrast with the surrounding tissues can be enhanced, and the lesions that cannot be detected by plain scanning and benign and malignant tumors can be found and identified. The time when the contrast agent enters the liver is different. When the contrast agent enters the arteries at an early stage, enhancement of the hepatic arteries and their branches can be observed, while the portal veins are darker and not enhanced. In the portal vein stage, the contrast agent enters the portal vein, which can show the enhancement of the portal vein, while the hepatic artery is darker, at which time the lesion of the portal vein can be clearly observed. It is worth noting that people with poor liver and kidney function and people with allergy to contrast agents are prohibited from doing enhanced CT. because metformin can react with contrast agents, so diabetic patients taking oral metformin stop taking the drug two before and after the examination. Be sure to drink plenty of water after the examination to expel the contrast agent from the body as soon as possible. If there is any discomfort, it is recommended that standardized treatment be carried out under the guidance of a professional doctor.