1. CDRH/FDA, Division of Imaging and Applied Mathematics, Bldg. 62, Rm 3124, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002, United States
2. University of Iowa, Departments of Radiology and Biostatistics, 3170 Medical Laboratories, 200 Hawkins Drive, Iowa City, Iowa 52242-1077, United StatescComprehensive Access and Delivery Research and Evaluation Center, VA Health Care System, Iowa City, Iow