Aortic aneurysms. Coloured 3D computed tomography (CT) scan of the chest of a 28 year old patient with several aneurysms throughout the entire aorta. They are seen here as 'nodules' along the aorta, with a particularly large aneurysm present at centre left. The aorta is the body's main artery, carrying 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 with repair or replacement of the vessel.