Aortoenteric Fistula


(Left) Graphic shows a fistula image between the transverse duodenum and aorta at the site of the graft-aortic suture line image.



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(Right) Axial CECT in a 70-year-old man presenting with fever and hematemesis months after abdominal aortic aneurysm (AAA) repair shows the native, calcified aortic wall image wrapped around a synthetic graft. A gas collection is noted between the graft and aortic wall image, indicating infection or fistula. Note the soft tissue density surrounding the aorta and 3rd portion of duodenum image.

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(Left) This elderly woman had pain and fever years after AAA repair. Axial CECT shows a calcified aortic wall wrapped around synthetic graft material image. At the level of the 3rd portion of the duodenum, the duodenal wall image appears to be adherent to the aorta. Note an enhanced focus image that may represent active bleeding or inflammation.


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(Right) Axial CECT in the same patient reveals several bubbles of extraluminal gas image; aortoenteric fistula with underlying infection was surgically confirmed.


TERMINOLOGY


Definitions




• Abnormal communication between aorta and gastrointestinal (GI) tract


IMAGING


General Features




• Best diagnostic clue
image Inflammatory stranding and gas between abdominal aorta and 3rd part of duodenum following aneurysm repair

• Location
image Duodenum (80%); jejunum and ileum (10-15%); stomach and colon (5%)


CT Findings




• Microbubbles adjacent to aortic graft

• Focal bowel wall thickening &/or perigraft soft tissue thickening > 5 mm

• Pseudoaneurysm, disruption of aneurysmal wrap

• Contrast in pseudoaneurysm on arterial phase

• Arterial phase: ↑ attenuation of intestinal lumen contents 
image Attenuation of intestinal contents may decrease on delayed phase through same region

image Volume of intestinal blood may increase on delayed phase

• CT-guided needle aspiration: May confirm perigraft infection


Nuclear Medicine Findings




• PET/CT
image Site of infection/fistula is usually FDG-avid on PET

• Tagged RBC study 
image Radiolabelled RBC accumulate within bowel at site of fistula

• Tagged WBC scan can confirm infection


Imaging Recommendations




• Best imaging tool
image CT: 94% sensitive; 85% specific

image PET/CT may be even better
– CT portion of exam should be of diagnostic quality with IV contrast administration

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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Aortoenteric Fistula
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