The Utility of Whole Body 18F-FDG PET-CT in Diagnosing Isolated Cardiac Sarcoidosis: The Western Australian Cardiac Sarcoid Study

Background It is reported that up to 29-52% of patients with cardiac sarcoidosis (CS) may have isolated cardiac sarcoidosis (ICS). The wide variation in prevalence may be related to the diagnostic methods for assessing extracardiac involvement. Whole-body F-18-fluorodeoxyglucose positron emission tomography-computed tomography (F-18-FDG PET-CT) imaging is a useful and increasingly used technique for screening for extracardiac involvement in cases of suspected ICS. This study aims to determine the rate of isolated cardiac involvement with clinically manifest CS using cardiac F-18-FDG PET-CT. Methods We performed a retrospective analysis of data in the West Australian Cardiac Sarcoid (WACaS) Database. After cardiologist review and workup, all cases of proven or probable CS, based on either current Heart Rhythm Society criteria for the diagnosis of CS or local expert consensus were included. Only patients who underwent whole body F-18-FDG PET-CT were included in the final analysis. Results Fifty-two (52) cases of CS were identified. Data on symptoms, imaging findings, treatment and outcomes were collected. Of the 42 patients who underwent diagnostic F-18-FDG PET-CT, 32 demonstrated changes consistent with CS. Of the 32, 69% were male, mean age 50 years at diagnosis. Only 3/32 (9.4%) patients had ICS. Pulmonary involvement occurred in 91% with varied involvement in other organs. The mean number of extracardiac sites at diagnosis was 2.2. Conclusions This study demonstrates the utility of F-18-FDG PET-CT in diagnosing extracardiac organ involvement in cases of CS. With the use of this modality, ICS may be rarer than previously reported.