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Figure
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Figure
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Figure
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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).
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:
Insufficient seal between graft and aortic wall. |
Type
II:
Retrograde collateral flow via aortic branches |
Type
III:
Graft defect or disconnection. |
Type
IV:
Graft porosity. |
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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.
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.
