FDG uptake patterns in PET/CT caused by inflammation and/or infection after graft surgery for thoracic aortic dissection

To identify FDG uptake patterns in PET/CT caused by infection, inflammation, surgical material and/or graft coating. Of 610 consecutive patients with thoracic aortic graft surgery, 60 patients with 187 PET/CT were retrospectively included. We quantified FDG uptake in all grafts, using maximum standardized uptake value (SUVmax) alone and in relation to liver background (SUVratio), and determined the uptake pattern. Mixed linear regression models with random slope and intercept were applied for the analysis of SUVratio over time and generalized estimating equations to analyze the associations with anastomosis uptake. FDG uptake was frequently focal (90%), higher in infected than in non-infected grafts (mean SUVratio 2.19; 95% CI 2.05-2.32 versus 1.63; 1.46-1.79, p<0.001), and decreasing slowly over time (SUVratio per year since surgery -0.048; 95% CI -0.15- 0.051, p=0.34), without a difference in slope between infected and non-infected grafts (p=0.52). There was no evidence of an interaction between SUVratio and use of BioGlue® surgical adhesive (intercept p=0.73, slope p=0.71), or graft coating (gelatin and collagen, all p>0.7). FDG uptake at the anastomosis was more frequent in non-infected than in infected grafts (66% versus 21%, odds ratio (OR) 11.34; 95% CI 3.61-35.66, p<0.001). This effect was attenuated by the use of BioGlue® (OR 5.05; 95% CI 0.45-56.9, p=0.19). FDG uptake in PET/CT after thoracic aortic graft surgery is higher in infected than in non-infected grafts. In non-infected grafts, focal uptake is also frequent, mostly anastomosis-associated, not associated with graft coating, and possibly affected by use of BioGlue®.