Aortic arch graft infection (FDG PET-CT)

Case contributed by A A


Admitted with bacteremia in the context of a previous Stanford type A (DeBakey I) aortic arch dissection repair 15 years earlier with graft in-situ. Trans-esophageal echocardiography negative for endocarditis. ?Graft infection ?endocarditis (native valves).

Patient Data

Age: 65 years
Gender: Male

Gross cardiomegaly associated with thoracic aortic dissection involving the distal ascending aorta extending into the arch and descending aorta with poor filling of the false lumen. Aortic arch branches are intact and there is no evidence of recent rupture into either the pericardium or pleural space.

Features of gross cirrhosis and portal hypertension with enlargement of the IVC and hepatic veins suggestive of right heart failure. Bibasal lung atelectasis and probable interstitial edema.

Whole body FDG PET/CT with dedicated cardiac gated series

Nuclear medicine

1. Intense near-circumferential FDG uptake associated with the ascending aorta, particularly anteriorly corresponding to the periphery of the false lumen and extending to just proximal to the origin of brachiocephalic trunk is concerning for infection.
2. Multiple mildly avid pulmonary opacities in bilateral lungs likely inflammatory in this context.
3. Peripheral FDG uptake associated with both knees (including fluid in right suprapatellar bursa) suggestive of inflammatory etiology.
4. Bilateral pleural effusions.

Case Discussion

Two weeks prior to presentation with sepsis, the patient inadvertently bumped a venous varicosity on his right ankle causing significant bleeding requiring emergency department presentation (managed with pressure and dressing). This was felt to represent the most likely source of bacterial ingress into the blood stream with demonstrated secondary infectious deposits in the grafted aortic arch and lung.

FDG PET is emerging as a useful diagnostic tool for investigating potential vascular graft infections with a recent case series of 34 patients demonstrating sensitivity and specificity of 96% and 86% respectively1. Additionally, the series suggested an SUVmax cut off value of ≥3.8 to differentiate between infected and non-infected grafts (p <0.001)1. Several studies have demonstrated sensitivity from 78-100% and specificity from 64-95%2-6.

Further supporting the argument for FDG PET in vascular graft infections is the ability to detect sequelae of bacteremia and graft infection such as distant septic emboli.

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