Purpose
Aortic graft infections are associated with significant mortality, and their clinical management presents a substantial challenge, particularly due to the need for early diagnosis. This study aimed to assess the diagnostic performance and potential therapeutic impact of 18F-fluorodeoxyglucose positron emission/computed tomography (FDG PET/CT) in comparison with contrast-enhanced CT (CE-CT) in outpatients with Marfan syndrome (MFS) and other hereditary aortic diseases (HTAD) presenting with suspected aortic graft infection.
Methods
FDG PET/CT and CE-CT examinations were retrospectively evaluated in 38 outpatients with MFS and HTADs who mostly presented with only mild or nonspecific clinical symptoms. All outpatients were non-surgical candidates and therefore received oral antibiotic therapy as needed throughout follow-up. For FDG PET/CT, diagnostic performance was analyzed based on maximum standardized uptake value (SUVmax) in the periprosthetic region and quantified metabolic active infection volume (MAIV). A multimodal reference standard incorporating clinical presentation, laboratory and microbiological results, and findings of conventional imaging was used to confirm the final diagnosis.
Results
Metabolically active aortic graft infection on FDG PET/CT occurred in 36 of 38 outpatients (95%), with a median SUVmax of 5.8 (IQR 4.6–8.5) and a MAIV of 29.4 cm³ (IQR 15–43.4). Patients with Dacron vascular grafts tended to exhibit higher SUVmax values than those with other graft materials. The sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and overall accuracy of FDG PET/CT were 100%, each, thus, outperforming CE-CT, which showed corresponding values of 24.1%, 100%, 4.3%, 100%, and 26.7%. Median C-reactive protein (CRP) was 3.75 mg L⁻¹ (95% CI 2.8–9.4), and median white blood cell count (WBC) was 7.9 × 10⁹ L⁻¹ (95% CI 6.5–9). Neither parameter correlated with SUVmax or MAIV. Blood cultures were obtained in all patients, with successful pathogen isolation in almost one third (28.9%). Oral antibiotic therapy was escalated or continued despite normal CRP and WBC values in 86.1% of positive FDG PET/CT examinations (31 of 36 patients). Successful therapy completion with correlating PET/CT results was achieved in 5 patients. A reduction in SUVmax and MAIV was seen in 41.7% (15 of 36 patients) under ongoing antibiotic therapy and clinical symptoms improved or vanished completely. Follow-up based on PET-CT examinations had a median duration of 741 days (IQR 455–903), during which two patients died.
Conclusion
FDG PET/CT accurately detects aortic graft infection in HTAD outpatients and is superior to contrast-enhanced CT, with substantial therapeutic impact even when infection parameters and clinical symptoms are not indicative. Clinical use for monitoring of aortic graft infections may be reasonable.
