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 ¹⁸F-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 ¹⁸F-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, ¹⁸F-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 ¹⁸F-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, ¹⁸F-FDG-PET/CT leads to a modification of the management in five patients.

CONCLUSION

Our findings support the utility of ¹⁸F-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.

[Infective endocarditis due to non-HACEK gram-negative bacilli in a Level III cardiovascular center in Argentina (1998-2016)]

Non-HACEK Gram-negative bacilli are a rare cause of infective endocarditis. Epidemiological, diagnostic and prognostic aspects of this entity are little known, and there is limited experience. The aim of this study was to analyze the clinical, microbiological and in-hospital outcomes of non-HACEK Gram negative bacilli endocarditis and to compare them with those due to other microorganisms.

Cardiac 18F-FDG PET/CT procedure for the diagnosis of prosthetic endocarditis and intracardiac devices

Infective endocarditis (IE) is a serious condition with a poor prognosis, its mortality unchanged significantly despite diagnostic and therapeutic advances in the last 30years. The diagnostic ability of the modified Duke criteria in prosthetic endocarditis and/or devices does not exceed 50%, so new tools are necessary for the diagnosis of this entity in this context. The ¹⁸F-FDG PET/CTA combines a highly sensitive technique to detect inflammatory-infectious activity with a technique with high anatomical resolution to assess the structural lesions associated with endocarditis. With a diagnostic sensitivity between 91-97%, this hybrid technique has become a useful diagnostic tool for patients with prosthetic valves or devices and suspicion of IE, becoming a major criterion in the diagnostic algorithm of current guidelines. This excellent diagnostic ability depends directly on the quality of the obtained exploration and the knowledge at the time of interpreting the images. The aim of this review is to describe and standardize the methodology of cardiac ¹⁸F-FDG PET/CTA in the diagnosis of endocarditis in prosthetic valves and intracardiac devices, with special emphasis on the particularities of the patient's preparation, the PET and CT acquisition procedures, and the subsequent imaging postprocessing and interpretation.