Feasibility of FDG PET in the cardiac inflammation.

The aim of the study was to assess the feasibility of FDG PET in cardiac inflammation with a particular focus on the delayed scan. Thirty-five consecutive FDG PET scans of patients with suspected or confirmed cardiac inflammation were retrospectively reviewed. The patients were referred for PET because of endocarditis (n = 16) or sarcoidosis (n = 19). Among them four patients had two consecutive for follow up and treatment control (two patients with sarcoidosis, two with endocarditis). In all of the cases a standard head to mid-thigh scan was performed 45-60 min after FDG injection as well as a delayed heart scan 1 h after the standard imaging was performed. FDG PET confirmed active inflammation in 10 out of 35 scans. Delayed scans in positive cases showed SUVmax value increase, but did not have an impact on the result, neither they did in negative cases-no significant differences between standard and delayed scan were found. Interestingly in 5 out of 14 cases with suspected endocarditis PET revealed the extracardiac inflammation focus, thus changing initial diagnosis. FDG PET also indicated which prosthesis caused inflammation if there were many. In the sarcoidosis group the aim was to confirm or exclude heart involvement (13 scans) or to assess the response to the steroid therapy (6 scans) in patients with previously confirmed sarcoidosis. PET revealed active heart disease in 3 initial scans, and 1 follow up scan. FDG PET is a valuable imaging method for the cardiac inflammation assessment. It adequately localises the active inflammation site. Also, since it is a whole-body scan it may detect the extracardiac inflammation foci, which in some cases may change the initial diagnosis. In our study the delayed scans showed no added value.