Narrowed renal artery. Coloured computed tomography (CT) scans from a patient with stenosis (narrowing) of the right renal artery. A 3D scan of the interior of the artery is seen at left, the exterior, seen using a contrast medium, is at right. The large blood vessel running from top to bottom at right is the aorta, the body's main artery. The right renal artery branches from the aorta and serves the right kidney (blue). The artery has become narrowed (indicated by the arrow) by atheroma, fatty deposits that thicken the inner coating of the arteries. The irregular shapes of the deposits can be seen in the endovascular image. Treatment is either with balloon angioplasty or a stent to reopen the artery.