Injecting contrast material into a vein allows timing of CT images to visualize specific organs.

“so we actually inject it into the vein and then we actually the heart pumps it around and so that means we're actually able to time when we actually take the CT image in order to be able to see what type of organ we're looking for so you can think of it if you actually get the arterial phase you'll actually see where the arteries are connecting to an organ or else you can wait for the venous phase or when the veins are returning blood flow from that organ and you actually see the entire detail of the organ”