Diagnostic challenges in infective endocarditis: is PET/CT the solution?

PURPOSE: Despite developments in both imaging and microbiological techniques, the final diagnosis of IE often remains challenging. In this single-center cohort study, we aimed to identify the specific indications for request of 18 F-FDG-PET/CT in clinical practice and to evaluate the diagnostic benefit of this nuclear imaging technique.

METHODS: A total of 235 patients with possible (n = 43) or definite (n = 192) IE according to the revised Duke criteria were prospectively studied from July 2013 until December 2016. Echocardiography was generally used as the primary cardiac imaging technique. All patients were treated by a multidisciplinary Endocarditis Team. Diagnostics with 18 F-FDG-PET/CT were undertaken on request by at least one member of the multidisciplinary team when overall diagnostics were inconclusive.

RESULTS: In 20 patients, 18 F-FDG-PET/CT scan was performed for additional diagnostic evaluation. Hereof, 15 patients had a history of implanted cardiac prosthetic material. In six patients with definite IE, the use of 18 F-FDG-PET/CT was helpful for further clarification of the diagnosis. In one patient with possible IE, the diagnosis could be reclassified to definite IE. In addition, one case of vertebral osteomyelitis as well as upper and lower leg abscesses and knee empyema were detectable as extracardiac foci. Furthermore, 18 F-FDG-PET/CT leads to a modification of the management in five patients.

CONCLUSION: Our findings support the utility of 18 F-FDG-PET/CT as an adjunctive diagnostic tool especially in the evaluation of prosthetic valve-/cardiac device-related IE and for the detection of extracardiac foci in some cases. However, due to remaining limitations also of this imaging technique, a multidisciplinary clinical evaluation still remains the essential basis for the diagnostic assessment.