Center for Rheumatology and Clinical Immunology, Division of Medicine, Turku University Hospital, Turku, Finland. Department of Medicine, University of Turku, Turku, Finland. Department of Infectious Diseases, Division of Medicine, Turku University Hospital, Turku, Finland. Turku PET Center, Turku University Hospital and University of Turku, Turku, Finland. Department of Radiology, Turku University Hospital, Turku, Finland. Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland.