Identification of the etiology of pericardial disease is challenging because the accessibility to pericardial fluid and tissue is limited and there is a relatively low yield of fluid and tissue analysis. Pericardial disease is associated with various systemic diseases and is frequently a first manifestation of other systemic diseases. Detecting the cause of pericarditis and minimizing the subsequent inflammatory process can possibly prevent long-term complications. PURPOSE OF REVIEW: To review the clinical utility of [18F]-2-deoxy-2-fluoro-D-glucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) in the diagnosis and treatment of pericardial disease. RECENT FINDINGS: [18F]FDG-PET/CT can visualize the hypermetabolic tissues of both malignancy and inflammation. Distribution of [18F]FDG-PET/CT uptake can provide information for neoplastic disease. If malignancy is ruled out, high uptake of pericardium is associated with active inflammation of the pericardium, and thus response to anti-inflammatory agents can also be predicted with [18F]FDG-PET/CT imaging. [18F]FDG-PET/CT can be helpful for diagnosing and establishing prognosis and for planning for anti-inflammatory treatment in pericardial disease.