- Pictorial Review
- Open Access
Multi-detector CT angiographic imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR)
© The Author(s) 2012
- Received: 22 September 2011
- Accepted: 3 April 2012
- Published: 12 June 2012
Multidetector computed tomography (MDCT) angiography represents the standard of reference in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR), being effective in the detection of the full spectrum of possible complications on both axial and 3D images.
The purpose of this article is to review the normal CT angiography findings of the different types of stent-grafts and to describe the radiological findings of early and late complications after EVAR on axial and reconstructed images. A selection of cases of post-EVAR MDCT angiography is presented to learn the techniques most commonly used for endovascular treatment, the correct CT scanning technique to acquire the data, the full gamut of possible procedure-related complications and how these complications usually appear on CT images.
MDCT angiography is an effective and specific technique in both the pre- and postoperative settings of EVAR procedures. A better understanding of the procedure, the devices, the normal postoperative imaging features and the possible procedure-related complications ensures optimal planning and follow-up of patients undergoing an EVAR procedure.
- Endovascular abdominal aortic aneurysm repair (EVAR)
- CT imaging
Endovascular aortic aneurysm repair (EVAR) has developed into a feasible and successful alternative to open surgery for the treatment of abdominal aortic aneurysms. EVAR can be offered to many patients with a suitable anatomy of the aorta and iliac arteries, regardless of comorbid conditions [1–3]. Despite the known excellent early results of EVAR in terms of the reduction in perioperative mortality, rate of complications and length of hospitalization, many patients require re-intervention during the middle and long-term follow-up because of procedure-related complications. For this reason, surveillance of these patients is crucial to determine the long-term performance of these devices [4, 5]. Because of the rapid diffusion of EVAR and the increased number of patients who undergo multidetector CT (MDCT) follow-up, the radiologist should be familiar with the full spectrum of possible procedure-related complications in order to allow their early diagnosis and treatment. The purpose of this article is to present a spectrum of post-EVAR complications as seen with MDCT.
CT acquisition protocol parameters
Rotation time (s)
Table feed (mm/s)
Slice thickness (mm)
Slice interval (mm)
4 × 1 mm
16 × 0.625 mm
64 ×0.625 mm
Since aneurysm exclusion is expected to be correlated with shrinkage, surveillance of aneurysm dimensions is mandatory for asserting the adequacy of aneurysm exclusion from the blood flow and for guiding the need for reintervention in selected cases. The aneurysm volume may increase slightly immediately after EVAR (3–4 mm), given the additional volume and the external force exerted by the stent-graft or, alternatively, the swelling of the aneurysm sac induced by perigraft thrombosis . On the other hand, the volume tends to increase if sac perfusion is present or decreases during the follow-up in the absence of endoleaks. Diameter measurements are most accurate if performed on axial images perpendicular to the aortic long axis, but volume assessment has been proven to be more accurate than diameter in the early detection of aneurysm growth; however, volume assessment is time-consuming and requires advanced processing, dedicated equipment and skilled operators .
Type I is caused by separation of the device from the arterial wall, resulting in leaks originating at the proximal and/or distal attachment sites of the graft because of a technical (e.g., suboptimal stent-graft diameter) or anatomical (e.g., a short, irregular, ulcerated or angulated landing zone without an optimal conformation of the stent-graft to the curved aortic contour) problems, or to its caudal migration. On CTA images, it often appears as a huge and circumferential leak, adjacent to the proximal or distal end of the prosthesis (Figs. 9 and 10).
Type II endoleaks are caused by back-filling of the aneurysm sac via branch vessels, such as the lumbar arteries and inferior mesenteric artery excluded by the stent-graft. On CTA images, the type II endoleak is most pronounced at the periphery of the aneurysmal sac, with little or no contact with the prosthesis, is commonly located in a posterior or lateral position, and is associated with opacification of the lumbar arteries. If an endoleak is located in the anterior position, a retrograde flow into the sac by the inferior mesenteric artery must be suspected (Fig. 11).
Type III endoleaks arise from a fabric tear, modular or graft disconnection, and are more likely when multiple prostheses with short overlapping areas are used. On CTA images, the leak is strictly adjacent to the prosthesis, with little or no contact with margins of the aneurysmal sac, without opacification of the lumbar arteries or inferior mesenteric artery (Fig. 12).
Type IV involves vascular flow caused by the high porosity of the graft, most likely created by the numerous suture holes holding the graft material to the stent. They are usually only detected on conventional angiograms performed at the end of the procedure.
Type V or endotension refers to a growth of the aneurysm sac but without demonstrable reperfusion defects (Fig. 13).
Type I and type III endoleaks require prompt treatment as they are associated with a high risk of sac rupture. However, the most common endoleak found in endovascular stent-grafting is the type II endoleak.
MDCT is the method of choice both in the pre- and postoperative setting of EVAR procedures. A better understanding of the procedure followed, the devices used, the normal postoperative imaging features and the possible procedure-related complications ensures an optimal planning and follow-up of patients who undergo an EVAR procedure. Finally, in order to better determine the long-term performance of these devices, strict surveillance of all patients is mandatory.
This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.
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