An angiographic catheter is a thin plastic tube. It is inserted into an artery through a small incision in the skin. Once the catheter is guided to the area being examined, a contrast material is injected through the tube and images are captured using a small dose of ionizing radiation x-rays. Catheter angiography is used to examine blood vessels in key areas of the body, including the brain, kidneys, pelvis, lungs and heart.