Fasting FDG-PET will be performed in all subjects. Serum calcium, C-reactive protein (CRP), angiotensin converting enzyme (ACE), lysozyme, and B-type natriuretic peptide (BNP) levels will be measured in all patients. All patients will undergo chest X-ray, resting 12-lead ECG, transthoracic echocardiography, and 3 types of radionucleotide imaging using Tc-99m sestamibi for myocardial perfusion, Ga and FDG for whole-body evaluation. All assessments will be conducted within 2 weeks and no sign indicated any change in disease activity of sarcoidosis. The patients with cardiac involvement will be treated with 30 mg/day of prednisolone orally for the first 4 weeks, then will decrease to a dose of 20 mg/day for the next 4 weeks, and will maintain to a dose of 10 mg/day afterwards.