Aneurysm
An artery is considered aneurysmal when its diameter equals or exceeds 1.5 times the normal diameter.
Thoracic aortic aneurysm
In general, the term aneurysm is used when the axial diameter is >5.0 cm for the ascending aorta and >4.0 cm for the descending aorta.
Abdominal aortic aneurysms (AAA) are focal dilatations of the abdominal aorta measuring 50% greater than the proximal normal segment, or >3 cm in maximum diameter.
