1. Department of Radiology, University College London Hospital, 235 Euston Rd, London NW1 2BU, UK.
2. Department of Diagnostic Radiology, National Jewish Health Main Campus, Denver, CO.
3. Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
4. Institute for Diagnostic Accuracy, Groningen, The Netherlands.
5. Università degli Studi di Parma, Facoltà di Medicina e Chirurgia, Parma, Italy.
6. Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.