1. Center for Evidence Based Imaging, Department of Radiology, Brigham and Women's Hospital, 20 Kent St, 2nd Fl, Boston, MA 02445.
2. Harvard Medical School, Boston, MA.
3. Department of Radiology, New York–Presbyterian/Weill Cornell Medical College, New York, NY.
4. Department of Healthcare Policy and Research, Weill Cornell Medical College, New York, NY.
5. Hospital of the University of Pennsylvania, Philadelphia. PA.
6. Present address: Department of Radiology, Stanford Hospital, Stanford, CA.
7. Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA.