Aortic stent-grafts: Endoleak surveillance

Endoleaks have been referred to as the “Achilles heel” of endovascular aortic aneurysm repair (EVAR) and are the most common complication of this procedure. An endoleak can maintain a high systemic blood pressure within the aneurysm sac, potentially leading to rupture. Follow-up is therefore mandatory to detect and classify possible endoleaks. Computed tomography (CT) remains the gold standard for follow-up, but provides no hemodynamic information on endoleaks and has the disadvantages of exposing patients to iodine contrast and X-ray radiation. Exposure to radiation could be reduced in various ways, by simplifying the triphasic protocol using dual-energy CT imaging, limiting the amount of radiation per slice using iterative reconstruction, and reducing the follow-up schedule that could be altered to include non-ionizing radiation imaging techniques. Contrast-enhanced ultrasound (CEUS) is an interesting alternative to CT, as is magnetic resonance (MR) imaging that can be used as an alternative or for complementary imaging. Long-term follow-up schedules are currently based on repeated CT. However, more recently alternative follow-up protocols have been proposed for patients with no endoleaks nor increase in aneurysmal sac size. These new protocols consist of CT imaging at 1 month and 1 year after treatment, subsequently followed by CEUS. Nevertheless, the mechanical structure of the stent-graft must still be verified by CT. The use of patient-specific risk-adjusted follow-up protocols, based on preoperative imaging and the first postoperative results, is gradually becoming more and more widespread.