Brain perfusion CT, also known as brain enhancement CT, refers to the use of contrast agent injected intravenously into the body to reflect the blood perfusion in brain tissue through CT imaging technology, mainly used for the diagnosis of cerebral embolism and brain tumor, which requires attention to the following points: a. The contrast agent is mostly iodine, and a skin test is required before the procedure, and a negative skin test can only be used. It is necessary to observe whether there are allergic reactions such as itching and rash during infusion. If an allergic reaction is found, it should be treated promptly. Most of the contrast agents are harmful to the kidneys. Patients with poor kidney function should carefully consider using this test, and some patients with poor kidney function need dialysis treatment after using this test. Third, patients with poor cardiopulmonary function also need to be carefully considered, because the contrast agent is rapidly entering the body through the veins, causing cardiopulmonary load, which may lead to heart failure, damage to cardiac and pulmonary function, and in serious cases can even be life-threatening. Fourth, patients with vasculitis and brittle blood vessels should also be carefully considered, which may cause rupture of blood vessels or leakage of contrast fluid leading to bleeding, vasculitis and a series of other problems. Five, after the completion of the examination need to observe half an hour to an hour, if no discomfort before leaving. Sixth, after the examination is completed, you need to drink more water and urinate more to promote the excretion of the contrast agent.