1Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada, Johns Hopkins University, Baltimore, Md
2Departments of Radiology, Johns Hopkins University, Baltimore, Md
3Collaborative Health Studies Coordinating Center, University of Washington, Seattle, Wash
4Department of Radiology, University of California–Los Angeles School of Medicine, Los Angeles, Calif
5Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minn
6Department of Radiology, Tufts Medical Center, Boston, Mass
7Medicine, Johns Hopkins University, Baltimore, MD
8Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bldg 10/1C355, Bethesda, MD 20892