Iodine contrast is injected into the body to better show the lesion, usually through the arterial phase, the venous phase, and the delayed phase to show the degree of enhancement of the lesion, which can better distinguish the boundary between normal and abnormal tissues, thus providing the clinical doctor with a tendency opinion on the benignity and malignancy of the lesion, and providing a reference for the next step of treatment. If there is a lesion on the liver, the boundary between the lesion and the normal tissue on the liver is better shown by enhancing the contrast injection. In addition, depending on how the lesion is enhanced, it is considered whether the lesion tends to be benign or malignant. Therefore, contrast is still very useful and can provide a better diagnostic opinion to the clinician and diagnosing physician.