Characteristics of FDG-PET findings in the diagnosis of systemic juvenile idiopathic arthritis

Objective: To examine and delineate inflammatory focus in patients with juvenile idiopathic arthritis (JIA), 18 F-Fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) ( 18 F-FDG-PET) was applied to patients with JIA, and the images of these patients were compared. Methods: Sixty-eight children (59 with systemic JIA (s-JIA) and 9 with polyarticular JIA) were included. The diagnosis of JIA was done to meet the International League of Associations for Rheumatology (ILAR) criteria. After 6-h fasting, whole-body positron emission tomography (PET) scans were acquired 60 min after intravenous injection of 3-5 MBq/kg 18 F-FDG. The interpretation of 18 F-FDG uptake was based on visual characteristics. Results: Two types of PET images were outstanding in s-JIA; one was 18 F-FDG uptake in red bone marrow, such as the spine, pelvis, and long bones as well as spleen (12 cases), and other type was the uptake in the major joints, such as hips, elbows, wrists, knees, and ankles (8 cases). The former findings were correlated with elevated levels of inflammatory markers, while the latter were with significantly increased levels of MMP-3 (p