1. Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
2. Mouse Imaging Facility, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland.
3. Laboratory for Functional and Molecular Imaging, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland.
4. Department of Bio-functional Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.