1. MedStar Clinical Research Center, MedStar Health Research Institute, Hyattsville, Maryland.
2. Nuclear Medicine Research, MedStar Washington Hospital Center, Washington, DC.
3. Division of Endocrinology, MedStar Washington Hospital Center, Washington, DC.
4. Division of Nuclear Medicine, MedStar Washington Hospital Center, Washington, DC.
5. Department of Biostatistics and Biomedical Informatics, MedStar Health Research Institute, Hyattsville, Maryland.