1. 1Kaiser Permanente Washington Health Research Institute, Kaiser Permanente WA, Seattle, Washington.
2. 2Department of Radiology, University of Washington and Seattle Cancer Care Alliance, Seattle, Washington.
3. 3Division of Biostatistics, Department of Public Health Sciences, University of California Davis, Davis, California.
4. 4Department of Medicine, University of California, San Francisco, California.
5. 5Department of Epidemiology and Biostatistics, University of California, San Francisco, California.
6. 6General Internal Medicine Section, Department of Veterans Affairs, University of California, San Francisco, California.
7. 7The Dartmouth Institute for Health Policy and Clinical Practice and Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.
8. 8Department of Radiology, University of North Carolina, Chapel Hill, North Carolina.
9. 9Department of Surgery, University of Vermont, Burlington, Vermont.
10. 10Department of Radiology, University of Vermont, Burlington, Vermont.
11. 11Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.