1. Department of Radiology, Brooke Army Medical Center, Fort Sam Houston, 3551 Roger Brooke Dr, San Antonio, TX 78234.
2. Department of Radiology, Uniformed Services University, Bethesda, MD.
3. Department of Medical Imaging, University of Arizona, Tucson, AZ.
4. Departments of Medicine and Biomedical Engineering, University of Arizona, Tucson, AZ.