1. Hitachi Medical Co., chaired, Department of Diagnostic and Interventional Imagiology, and Department of Nuclear Medicine and Diagnostic Imaging, Kyoto University, Kyoto 606-8507, Japan, Department of Radiology, Otsu Municipal Hospital, Otsu 520-0804, Japan, Research Reactor Institute, Kyoto University, Osaka 590-0494, Japan, and Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892