Background: Cardiac implantable electronic devices (CIEDs) chronic infection diagnosis is challenging because the clinical presentation is frequently misleading and echocardiography may be inconclusive. The aim of this study was to evaluate the diagnostic value of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (CT) and radiolabeled white blood cells single photon emission CT/CT in a cohort of patients who underwent both scans for suspicion of CIED infection and inconclusive routine investigations. Methods: Forty-eight consecutive patients with suspicion of CIED infection who underwent both 18 F-fluorodeoxyglucose positron emission tomography/CT and white blood cell single photon emission CT/CT in a time span ≤30 days were retrospectively included. The final diagnosis of CIED infection by the endocarditis expert team was based on the modified Duke-Li classification at the end of follow-up. 18 F-Fluorodeoxyglucose positron emission tomography/CT and white blood cell single photon emission CT/CT scans were independently analyzed blinded to the patients’ medical record. Results: In the overall study population, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were respectively 80%, 91%, 80%, and 91% for 18 F-fluorodeoxyglucose positron emission tomography/CT and 60%, 100%, 100%, and 85% for white blood cell single photon emission CT/CT. Addition of a positive nuclear imaging scan as a major criterion markedly improved the Duke-Li classification at admission. Semiquantitative parameters did not allow to discriminate between definite and rejected CIED infection. Prolonged antibiotic therapy before imaging tended to decrease the sensitivity for both techniques. Conclusions: Nuclear imaging can improve the diagnostic performances of the Duke-Li score at admission in a selected population of patients with suspected CIED infection, particularly when the infection was initially graded as possible. Whenever possible, imaging should be performed before or early after antibiotic initiation.

In this study, we found that the analysis of the vascular region with the highest F-FDG uptake using either visual or numerical metrics provided the best diagnostic performance for the detection of active TAK with PET.