 Saccular aneurysms are spherical in shape and involve only a portion of the vessel wall; they vary in size from in diameter, and are often filled, either partially or fully, by a thrombus.Fusiform aneurysms ("spindle-shaped" aneurysms) are variable in both their diameter and length; their diameters can extend up to .They often involve large portions of the ascending and transverse aortic arch, the abdominal aorta, or less frequently the iliac arteries.