At present, there are two types of contrast agents usually used: ionic (Anchignafen) and non-ionic (Uvexan). The former is inexpensive, but has damage to kidney function; the latter has the characteristics of water solubility and easy diffusion, and has small side effects, high clarity and very few allergic reactions, but is more expensive. 1. A few people will experience warm sensation, nausea, vomiting, dizziness and sneezing when injecting iodine-containing contrast agents, which will usually subside within a short period of time. 2.People with allergic constitution may have more serious reactions, such as generalized hives, shivering and difficulty in breathing. 3.For atopic patients, laryngeal edema, shortness of breath, decreased blood pressure, cardiopulmonary failure, shock and sudden death may occur very rarely. The incidence of all adverse reactions is 3.1% to 12.7%, while the incidence of serious systemic reactions is 0.04% to 0.2%, with a mortality rate of about 1 in 100,000. 5. Subjects with the following conditions are more likely to have serious contrast reactions: those who have had adverse reactions to contrast injections, poor renal function, allergic asthma, multiple myeloma, other allergic history, uncontrolled hyperthyroidism, pheochromocytoma. Severe respiratory insufficiency (pulmonary edema, asthma), severe cardiovascular disease (congestive heart disease; severe or unstable heart rate irregularities), age greater than seventy years. It is important that these patients consult with their physician before filling out the consent form before being examined.