Objectives

To investigate the diagnostic value of simultaneous hybrid cardiac magnetic resonance (CMR) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for detection and differentiation of active (aCS) from chronic (cCS) cardiac sarcoidosis (CS).

Background

Late gadolinium enhancement (LGE)-CMR and FDG-PET are both established imaging techniques for the detection of CS. However, there is limited data regarding the value of a comprehensive simultaneous hybrid CMR/FDG-PET imaging approach also including CMR mapping techniques.

Methods

Forty-three patients with biopsy-proven extracardiac sarcoidosis (age 48 ± 12 years; 35% female) were prospectively enrolled for evaluation of suspected CS. After dietary preparation for suppression of myocardial glucose metabolism, patients were evaluated on a 3 Tesla hybrid PET/MR scanner. CMR protocol included T1 and T2 mapping, myocardial function and LGE imaging. We assumed aCS, if PET and CMR (i.e. LGE or T1/T2 mapping) were both positive (PET+ CMR+), cCS if PET was negative but CMR (i.e. LGE or T1 mapping) was positive (PET- CMR+), noCS if patients were CMR negative irrespective of PET findings.

Results

Among the 43 patients myocardial glucose uptake was suppressed successfully in 36 (84%). Hybrid CMR/FDG-PET revealed aCS in 13 (36%) patients, cCS in 5 (14%) patients, and no CS in 18 (50%) patients. LGE was present in 14 (39%) patients; T1 mapping was abnormal in 10 (27 %) patients and T2 mapping abnormal in 2 (6%) patients; 4 out of 18 CS patients (22%) were LGE-negative in whom CS was diagnosed based on abnormal T1 mapping findings. PET showed positive findings in 17 (47%) patients.

Conclusions

Comprehensive simultaneous hybrid CMR/FDG-PET imaging is useful for the detection of CS and provides additional value for identifying active disease. Our results may have implications for enhanced diagnosis as well as improved identification of patients with aCS in whom anti-inflammatory therapy may be most beneficial.