Enhanced CT exam is to observe the blood supply and occupancy of the vascular condition, parenchymal organ condition by metabolizing the contrast agent in the vessel after it is injected into the vessel. Enhanced CT shows the arterial phase 30 seconds after the contrast is injected into the vessel and the venous phase after 15 seconds. Both of them are the visualization of the parenchymal organs of the blood vessels after the process of contrast agent metabolism, which can mainly distinguish the aneurysm of the arterial phase and the occupancy of the parenchymal organs of the tumor. The venous phase is mainly observed for venous lesions, cancerous thrombi, venous hemangiomas, and venous shadows. The arterial phase and venous phase are different periods to observe the lesions and can be visualized separately.