Aortic Stent Graft Endoleak

Figure 1

History: 74-year-old male who is status post aortic stent graft placement for abdominal aortic aneurysm was referred to Main Street Radiology for CT angiography as a routine follow-up evaluation.

Findings: On the axial image (Figure 1), contrast opacification of a patent inferior mesenteric artery (IMA) is seen (yellow arrow) with contrast within the lumen of the aneurysm (red arrow) indicating an "endoleak". Normal opacification of the stent graft (small arrows) is noted.

The 3D reconstructed images (Figures 2 and 3) demonstrate a prominent left colic artery (yellow arrow) with retrograde flow to the IMA (white arrow).

Figure 2

Discussion: Endovascular repair of abdominal aortic aneurysm has been accepted as an effective alternative to open surgical repair, with decreased operative mortality and serious complications (NEJM 2004;351:1607-18). However, with minimally invasive placement of aortic stent grafts, there is a slightly higher rate of local vascular complications compared to open surgery (Radiology 2002; 224:739-747), due to leaks from the stent graft into the lumen of the aneurysm ('endoleak"). CT angiography has been shown to be the most sensitive test in detecting endoleaks.

Type I endoleak is found during the placement of the stent-graft, and should be corrected before the patient leaves the operating/procedure room.

Type II endoleak is most common, and typically involves retrograde flow into the aneurysm sac via a patent IMA or lumbar artery. A type II endoleak may not prove to be clinically significant. Follow-up CT angiography should be performed to assess the presence of the leak as well as measure the outer diameter of the aneurysm. Intervention should be considered if the aneurysm increases in size. Thrombosis of the involved vessel can be obtained percutaneously by an interventional radiologist.

Figure 3

Type III endoleak needs to be corrected, usually in the interventional radiology suite.

Type IV endoleak is rarely encountered with newer generation stents.

At Main Street Radiology, we routinely perform CT angiography of the abdominal aorta. 3D and multiplanar 2D images are generated which guide the vascular surgeon and interventional radiologist in planning the appropriate treatment. When performing follow-up studies after stent graft placement, we also perform "delayed" images which have shown to increase the sensitivity in detecting endoleaks.