Coloured 3D computed tomography (CT) angiogram scan showing atheromatous plaques (white) in the abdominal aorta (from top centre to centre) and iliac arteries (branching from centre) of a 64 year old male patient. Atherosclerosis is a condition in which an artery wall thickens as a result of accumulations (atheromas) of fatty materials such as cholesterol. The patient has previously had an aortofemoral bypass, where blood flow is redirected through an artificial blood vessel (graft, orange, centre to lower left) to avoid a blockage.