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 1month and 1year 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.