1. Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada