The value of 18F-FDG PET/CT in diagnosing infectious endocarditis

Purpose Early detection of infectious endocarditis is challenging. For diagnosing infectious endocarditis, the revised Duke criteria are the gold standard. Evidence of endocardial involvement on echocardiography is a major criterion, but sensitivity and specificity of echocardiography are not optimal. Here we investigated the utility of F-18-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) to diagnose infectious endocarditis in patients with gram-positive bacteraemia. Methods Seventy-two patients with gram-positive bacteraemia were prospectively included. Patients with a positive blood culture growing Staphylococcus aureus, Streptococcus species or Enterococcus species were eligible when a risk factor for developing metastatic infectious foci was present. Infectious endocarditis was defined according to the revised Duke criteria. All patients underwent F-18-FDG PET/CT and echocardiography. F-18-FDG uptake in or around the heart valves was evaluated independently by two nuclear medicine physicians. Results Sensitivity for diagnosing infectious endocarditis with F-18-FDG PET/CT was 39 % and specificity was 93 %. The positive predictive value was 64 % and negative predictive value was 82 %. The mortality rate in patients without infectious endocarditis and without increased F-18-FDG uptake in or around the heart valves was 18 %, and in patients without infectious endocarditis but with high F-18-FDG uptake in or around the heart valves the mortality rate was 50 % (p=0.181). Conclusion F-18-FDG PET/CT is currently not sufficiently adequate for the diagnosis of infectious endocarditis because of its low sensitivity. Improvements such as patient preparation with low carbohydrate-fat allowed diet and technical advances in the newest PET/CT scanners may increase sensitivity in future studies.