1. Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 9000 Rockville Pike, Bldg 10, Bethesda, MD 20892.
2. Genitourinary Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD.
3. Biostatistics and Data Management Section, Office of the Clinical Director, National Cancer Institute, Rockville, MD.