Graft in artery. Coloured computed tomography (CT) scan of a stent graft (red) in the aorta of a patient after the repair of an abdominal aortic aneurysm. An aneurysm is the swelling of part of an artery due to a weakness in its wall. The swelling fills with blood and may rupture, with fatal consequences, if left untreated. Treatment involves removing the weakened part of the artery and replacing it with an artificial graft, which is held open by a splint-like stent. This aneurysm occurred in part of the aorta (the main artery of the body) in the abdomen. CT scans use X-rays to construct images of parts of the body.