Diagnostic value of ¹⁸F-FDG PET/CT in infective endocarditis

18F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET/CT) is not routinely recommended for the diagnosis of infective endocarditis (IE) due to the lack of clinical impact.

Between January 2016 and January 2020, clinical data from patients with a possible diagnosis of IE were reviewed retrospectively to evaluate the value of ¹⁸F-FDG-PET/CT in the diagnosis of IE. ¹⁸F-FDG PET/CT scan was performed as an additional diagnostic tool in possible IE when echocardiography was inconclusive or in patients with definite IE to identify extracardiac complications. Cases were classified according to modified Duke criteria as rejected, definite or possible.

313 patients with suspected IE were included. 72 (23%) patients underwent 18F-FDG PET/CT. ¹⁸F-FDG PET/CT resulted in a reclassification of Duke criteria in 29/72 (40%) patients, from "possible" to "definite" (n, 10) and to "rejected" (n, 19). Patients who benefited from a Duke criteria reclassification following ¹⁸F-FDG PET/CT were more frequently classified as possible IE at inclusion or had a non-conclusive baseline echocardiography (100% vs 58%; p 0.001) and had more likely a prosthetic metallic valve replacement (59% vs 21%; p 0.001). Abnormal perivalvular uptake was identified in 46 patients (71% prosthetic vs 50% native; p 0.118). ¹⁸F-FDG PET/CT identified extracardiac uptake consistent with septic emboli in 14/72 (19%) patients. In addition, extracardiac uptake indicative of an alternative diagnosis was identified in 5 patients (2% prosthetic vs 17% native; p 0.039).

The use of ¹⁸F-FDG-PET/CT has shown to be useful in the diagnosis of IE, particularly in prosthetic IE and may provide additional value in the detection of septic emboli and/or the identification of an alternative diagnosis different from IE.