1. Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8585.
2. Department of Radiology, University of Illinois College of Medicine, Chicago, IL.
3. Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT.
4. Boston Biostatistics Research Foundation, Framingham, MA.