Supporting imaging modalities for improving diagnosis of prosthesis endocarditis: preliminary results of a single-center experience with 18F-FDG-PET/CT

BACKGROUND The aim of the current study was to evaluate the role of PET-CT in the diagnosis of prosthetic valve endocarditis (PVE). METHODS This is a single-center study including 13 PET/CT examinations performed between February 2009 and March 2016 in 13 patients (76.9% men, mean age 68.1 years, IQR 11.1) because of suspect of PVE. Median interval time between first operation and PET/CT examination was 19.02 months (IQR 85.5). Final diagnosis was made according to pathological criteria (histological and microbiological) of the Duke classification. RESULTS Eleven patients (84.6%) presented at the hospital admission positive blood cultures. Eight patients (61.5%) had inconclusive transesophageal echocardiography (TEE). Abnormal 18F-FDG uptake suggestive of active PVE was observed in 10 patients (76.9%), whereas in 3 patients (23.1%) PET/CT did not show any pathological tracer uptake at the level of the previous implanted prostheses. PET/CT revealed 15 (115.4%) new extracardiac findings and one (7.7%) new cardiac focus not previously detected in TEE. All patients underwent redo surgery. Matching the intraoperative findings with those of PET/CT, a total of 10 true positives, 2 true negatives, no false positive and 1 false negative finding was reported. Sensitivity, specificity, and positive and negative predictive values of PET/CT were 90.9%, 100%, 100% and 50% whereas for TEE they were 81.82%, 50%, 81.82%, and 50% respectively. In 61.63% of patients (N. 8) PET/CT and echo findings were concordant. In those cases the diagnosis of endocarditis was confirmed in all. CONCLUSIONS This study highlights the potential advantages of PET-CT in patients with suspected prosthesis endocarditis. Further prospective evaluations are needed to confirm those preliminary results.