Non-Invasive Characterization in Cardiac Sarcoidosis

Inclusion Criteria: 1. 18 years of age or older 2. must have undergone a cardiac positron emission tomography (PET) scan using 18F-fluorodeoxyglucose (FDG) for clinical reasons (i.e. referred by your doctor) within the preceding 30 days which showed evidence of active inflammation in your heart. Exclusion Criteria: 1. If you have two copies of a genetic variation called rs6971 which will prevent this tracer from generating high-quality images you may not participate. If you consent, a blood sample will be drawn to check whether you have this genetic variation. 2. Pregnancy or breastfeeding. If you are female and still experience menstrual periods, you must be willing to use contraception until your participation in the study is complete. 3. Allergy or intolerance to contrast dye containing gadolinium 4. Claustrophobia which would prevent you from completing an approximately one hour MRI scan 5. Inability to lie flat with your arms by your head 6. Abnormal kidney function (estimated GFR(glomerular filtration rate) \<60 ml/min/1.73 m2) 7. Implanted pacemaker, defibrillator or other medical devices which are not safe for 3 Tesla MRI 8. Metal in the eyes or shrapnel in the body 9. If you are clinically unstable you may not participate in this study. For example, if you have potentially life threatening abnormal heart rhythms which are not controlled by medication or other treatments, you cannot participate. Also, if you need medications to increase your blood pressure or cardiac function due to weak heart muscle, you cannot participate. \-