1. From the Biomedical and Metabolic Imaging Branch (R.O., A.H., J.M., K.Z.A., A.M.G.) and Diabetes, Endocrinology, and Obesity Branch (Z.A.S., K.Y.C., A.M.C.), National Institute of Diabetes and Digestive and Kidney Diseases, 10 Center Dr, Bldg 10-CRC, Room 3-5340, Bethesda, MD 20892-1263; and Cancer Imaging Program, National Cancer Institute, Bethesda, Md (J.F.E.).