Infected thoracic aortic graft

Case contributed by Dr Sally Ayesa

Presentation

Dacron thoracic aortic graft inserted 12 months ago. Presenting after fevers and rigors for 4 days. CRP 250.

Patient Data

Age: 60
Gender: Male
X-ray

Midline sternotomy wires are present. There is widening of the right lower paratracheal stripe. The aortic knuckle appears preserved. 

Bands of subsegmental atelectasis or scarring at the lung bases. 

The pleural recesses are clear.

An ascending aortic graft is in situ. No dissection flap or extra-luminal leak of contrast demonstrated.

There is abnormal complex fluid or soft tissue density abutting the right side of the ascending aorta, and extending into the right paratracheal region, with fat stranding in the anterior mediastinum.  No definite rim enhancement. Multiple mildly enlarged mediastinal and right hilar nodes. 

Small right effusion and basal atelectasis have been partly imaged. 

FDG PET/CT

Nuclear medicine

Corresponding to the complex fluid/soft tissue density in the right para-aortic and right paratracheal regions, there is intense FDG uptake. Especially in the anterior component, FDG uptake is peripheral with central photopaenia suggestive of necrosis. Abnormal uptake abuts the arch of the aorta. 

Abnormal hypermetabolism in the wall of the ascending aorta extending from the aortic root superiorly may be inflammatory related to the in situ graft, or reactive secondary to the adjacent mediastinal process. 

Mild hypermetabolism in the right pleural effusion. 

Physiological uptake elsewhere. 

Case Discussion

This patient was found to have an infected ascending aortic graft which manifested with a mediastinal abscess. Bacterial infection is often intensely hypermetabolic, with abscesses typically demonstrating peripheral FDG uptake and central photopaenia where there is necrotic tissue. FDG PET/CT was useful in confirming the diagnosis and guiding further management.

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