[¹⁸F]FDG Uptake in Non-Infected Endovascular Grafts: A Retrospective Study

Purpose: After endovascular aneurysm repair (EVAR), an increased [¹⁸F]FDG uptake may be observed at PET/CT, being common to both vascular graft/endograft infection (VGEI) and sterile post-surgical inflammation. Increased non-specific metabolic activity, due to foreign body reaction, can persist for several years after surgery, thus complicating the interpretation of PET/CT studies. In this paper, we aimed to assess [¹⁸F]FDG distribution at different time-points after the implant of abdominal Endurant^® endografts in patients without suspicion of infection. Methods: We retrospectively evaluated [¹⁸F]FDG/CT in 16 oncological patients who underwent abdominal aortic aneurysm exclusion with Endurant^® grafts. Patients had no clinical suspicion of infection and were followed up for at least 24 months after scan. [¹⁸F]FDG PET/CT scans were interpreted using both visual and semi-quantitative analyses. Results: The time between the EVAR procedure and [¹⁸F]FDG PET/CT ranged between 1 and 36 months. All grafts showed mild and diffuse [¹⁸F]FDG uptake without a focal pattern. Mean values of SUVmax were 2.63 ± 0.48 (95% CI 2.38-2.88); for SUVmean 1.90 ± 0.33 (95% CI 1.72-2.08); for T/B ratios 1.43 ± 0.41 (95% CI 1.21-1.65). SUVmax and SUVmean were not correlated to the time elapsed from the procedure, but we observed a declining trend in T/B ratio over time. Conclusions: Endovascular implant of Endurant^® grafts does not cause a significant inflammatory reaction. The evidence of faint and diffuse [¹⁸F]FDG uptake along the graft can reliably exclude an infection, even in early post-procedural phases. Therefore, in patients with a low probability of VGEI, [¹⁸F]FDG PET/CT can also be performed immediately after EVAR.