Feasibility of cardiac preparation protocol in the diagnostic of endocarditis with FDG-PET CT in clinical routine

Ziel/Aim:

To examine the feasibility of a preparation protocol for suppression of the physiological FDG uptake in myocardium in the diagnosis of endocarditis in clinical routine.

Methodik/Methods:

23 patients (age 71 ± 15y) with suspected infectious disease, which were referred to FDG-PET-CT were included in the analysis. 8 had been reported to have abnormal echocardiographic findings or positive blood culture. All patients underwent a fasting diet including a fasting period of> 12h, a high protein/fatty acid diet without carbohydrates for at least 24h and heparin injection(50UI/kgBW) 15minutes prior FDG injection. Whole-body PET-CT and a delayed scan(90 – 120 min p.i.) of the cardiothoracic region was performed. Elevated FDG uptake in the area of the valves above the level of the mediastinal blood pool was interpreted as suggestive for endocarditis. Quality of myocardial FDG-uptake suppression was assessed visually by comparing the maximum uptake of myocardium to blood pool and liver uptake.

Ergebnisse/Results:

The preparatory protocol significantly reduced physiological myocardium uptake in 87% of the patients, in 57% the physiological uptake was completely suppressed. 22% (5/23) depicted focal FDG accumulation in the area of one or more valves suggestive for endocarditis. 3 patients had elevated cardiac uptake outside the valve region consistent with infection. In all cases conspicuous uptake was observed in both scans, the delayed scan demonstrated increase of FDG accumulation. In 15/23 pts. whole-body PET-CT yielded additional extracardiac FDG-Uptake and in 10/23 only extracardiac foci were observed.

Schlussfolgerungen/Conclusions:

Vigorous preparatory protocols allow to significantly reduce physiological myocardial uptake in the majority of patients. This facilitates the diagnosis of endocarditis. Additional delayed imaging though improving visual contrast does not result in delineation of additional foci. Whole-body imaging resulted in the identification of extracardiac sites in 65% of the patients' population and appears mandatory.