1. Division of Rheumatology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
2. Department of Radiology, Cleveland Clinic, Cleveland, Ohio
3. Division of Rheumatology, Department of Pediatrics, Center for Pediatric Clinical Effectiveness, Children's Hospital of Philadelphia and Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA