What are endoleaks, and what imaging technique is used to find them?
An endoleak is defined as residual blood flow in the “aneurysm sac” (in other words, between the native aortic wall and the wall of the stent-graft). This complication is subcategorized into 5 types based on the origin of the blood flow to the aneurysm sac. Type II endoleaks are the most common and are related to reversed flow into the aneurysm sac from collateral vessels such as the inferior mesenteric artery or lumbar arteries ( Figure 13-6 ). Screening for endoleaks is usually performed with CTA or MRA. An appropriate protocol requires precontrast images and postcontrast arterial phase and delayed phase images because endoleaks may sometimes be identified only on delayed phase images. CT and MRI cannot always delineate the type of endoleak, and catheter angiography may be required to define the type of endoleak. Many endoleaks can be repaired percutaneously with coil or glue embolization.