1. From the Department of Radiological Sciences, University of California-Irvine School of Medicine, Orange, Calif (J.E.B.); and Imaging Biomarkers and Computer-Aided Detection Laboratory, Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Building 10, Room 1C224, MSC1182, Bethesda, MD 20892-1182 (J.Y., R.M.S.).