1. Department of Radiology, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114.
2. Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA.
3. Harvey L. Neiman Health Policy Institute, Reston, VA.
4. School of Economics, Georgia Institute of Technology, Atlanta, GA.
5. Department of Radiology, New York University Langone Medical Center, New York, NY.