Evaluation of the Prognostic Value of PET/MRI in Cardiac Sarcoidosis

Inclusion Criteria: * Age ≥ 18 years * Sarcoidosis defined according to ATS/ERS/WASOG criteria * Suspicion of cardiac involvement in sarcoidosis: * Clinical manifestations (syncope, lipothymia, persistent palpitations, signs of heart failure) and/or * Cardiac rhythm or conduction disorder (Mobitz type 2 atrioventricular block (AVB), AVB 3, right or left bundle branch block, Q wave in at least 2 leads, ventricular arrhythmia (ventricular mono/polymorphic complexes\> 1000 per 24 h, ventricular tachycardia, ventricular fibrillation), unexplained sustained VT or epsilon wave) and/or * Compatible cardiac ultrasound abnormality: left ventricular dilatation, septal thickening or wall thinning (especially basal), segmental kinetic disorder and wall aneurysm without coronary anomaly, altered left ventricular ejection fraction, altered diastolic function, altered right ventricular systolic function. * Informed patient consent * Membership of a social security scheme Exclusion Criteria: * Psychiatric illness not controlled by treatment * Claustrophobia * Known pregnancy or breast-feeding patient * Unbalanced diabetes (influence on carbohydrate metabolism for PET) * Previous infarction or known coronary disease * Known allergy to gadolinium and fluoro-desoxyglucose and their excipients * Renal insufficiency (Clairance \< 30 mL/min/1.73m2) * Implanted pacemaker not compatible with a 3 Teslas magnetic field * Patients with ocular metallic foreign bodies, pacemakers, neurostimulators, cochlear implants, metallic heart valves, vascular clips formerly implanted on cranial aneurysms and, in general, any non-removably implanted electronic medical equipment * Inability or refusal to follow a low-carbohydrate diet for 24 hours, followed by a 6-hour fast required prior to the examination * Patient unable to hold a 10-second apnea. * Patient deprived of liberty by judicial or administrative decision * Patient under legal protection (guardianship, curatorship) * Participation in other interventional research involving the human person or being in the exclusion period following previous research involving the human person * Patients under AME Exclusion criteria (post signature of consent) for women of reproductive age : \- Positive pregnancy test result after inclusion