1. Department of Radiology University of Pennsylvania Philadelphia PA USA
2. Drexel University College of Medicine Philadelphia PA USA
3. Department of Radiology Children's Hospital of Philadelphia Philadelphia PA USA
4. Department of Nuclear Medicine Odense University Hospital Odense Denmark
5. Division of Rheumatology Corporal Michael J. Crescenz VA Medical Center Philadelphia PA USA
6. Division of Rheumatology University of Pennsylvania Philadelphia PA USA
7. Department of Epidemiology and Biostatistics University of Pennsylvania Philadelphia PA USA