Coloured computed tomography (CT) scan of the abdomen of a 57 year old male patient with a slight aneurysm (dilation) of the abdominal aorta (down centre) below the kidneys (purple). The aorta is the body's main artery, it carries blood from the heart to the rest of the body. An aneurysm is a blood-filled dilation in a blood vessel caused by a weakened vessel wall. If left untreated aneurysms rupture and are often fatal. Treatment is by strengthening the aorta wall with a mesh stent.