1. Department of Radiology and Medical Imaging, University of Virginia Health System, PO Box 800170, 1215 Lee St, Charlottesville, VA 22908-1070.
2. Department of Radiology, Stanford University, Palo Alto, CA.
3. Department of Radiology and Imaging Services, Emory University School of Medicine, Atlanta, GA.
4. Department of Radiology, University of Iowa School of Medicine, Iowa City, IA.
5. Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD.