Background:18 F-FDG PET/CT has been added as a major criterion in the ESC 2015 infective endocarditis guidelines, but the benefit of the ESC criteria has not been prospectively compared with the conventional Duke criteria
Objectives:1. Primary objective: To assess the value of the ESC criteria including 18 F-FDG-PET/CT in prosthetic valve infective endocarditis (PVE). 2. Secondary objectives i: to assess the reproducibility of 18 F-FDG-PET/CT, ii: to compare its diagnostic value with that of echocardiography, and iii: to assess the diagnostic value of the presence of a diffuse splenic uptake
Methods :Between 2014 and 2017, 175 patients with suspected PVE were prospectively included in 3 French centers. After exclusion of patients with uninterpretable 18 F-FDG PET/CT, 115 patients were evaluated, including 91 definite and 24 rejected IE, as defined by an expert Consensus.
Results :Cardiac uptake by 18 F-FDG PET/CT was observed in 67/91 patients with definite PVE and 6 with rejected IE (sensitivity 73.6% 95%CI: 63.3 to 82.3%, specificity 75% 53.3% to 90.2%). The ESC 2015 classification increased the sensitivity of Duke criteria from 57.1% 46.3 to 67.5% to 83.5% 74.3% to 90.5%, (p< 0.001) but decreased its specificity from 95.8% 78.9% to 99.9% to 70.8% 48.9% to 87.4%. Intraobserver reproducibility of 18 F-FDG PET/CT was good (kappa= 0.84) but inter observer reproducibility was less satisfactory (kappa= 0.63). A diffuse splenic uptake was observed in 24 (20.3%) patients, including 23 (25.3%) of definite PVE, and only 1 (4.2%) rejected PVE (p=0.024).
Conclusion :18 F-FDG PET/CT is a useful diagnostic tool in suspected PVE, and explains the greater sensitivity of ESC criteria compared to Duke criteria. However, 18 F-FDG PET/CT also presents important limitations concerning its feasibility, specificity and reproducibility. Our study describes for the first time a new endocarditis criterion, i.e. the presence of a diffuse splenic uptake on 18 F-FDG PET/CT.