Cardiac sarcoidosis: the role of cardiac MRI and 18F-FDG-PET/CT in the diagnosis and treatment follow-up.

Sarcoidosis is a multi-factorial inflammatory disease characterised by the formation of non-caseating granulomas in the affected organs. Cardiac involvement can be the first, and occasionally the only, manifestation of sarcoidosis. The prevalence of cardiac sarcoidosis (CS) is higher than previously suspected. CS is associated with increased morbidity and mortality. Thus, early diagnosis is critical to introducing immunosuppressive therapy that could prevent an adverse outcome. Endomyocardial biopsy (EMB) has limited utility in the diagnostic pathway of patients with suspected CS. As a result, advanced imaging modalities, i.e. cardiac magnetic resonance imaging (MRI) and positron emission tomography with ¹⁸F-Fluorodeoxyglucose/computed tomography scan (¹⁸F-FDG-PET/CT), have emerged as alternative tools for diagnosing CS and might be considered the new 'gold standard'. This focused review will discuss the epidemiology and pathology of CS, when to suspect and evaluate CS, highlight the complementary roles of cardiac MRI and ¹⁸F-FDG-PET/CT, and their diagnostic and prognostic values in CS, in the current content of guidelines for the diagnostic workflow of CS.