To distinguish the arterial phase of enhanced CT from the venous phase, first of all, for enhanced CT examination, the plain scan is done first to observe the internal organs, then the drug is injected into the vein, and then the CT scan is performed, and the arterial blood can be seen in the arteries, which is bright in color and high in density, this is the arterial phase of enhanced CT. After the arterial phase, the contrast agent enters into the vein, which causes the blood in the vein to be high density, so at this time, through the enhanced CT scan, you can see the vein is bright color, which is the main manifestation to distinguish the arterial phase of enhanced CT from the venous phase.