1. Faculty of Medicine and University Hospital Cologne Institute of Radiochemistry and Experimental Molecular Imaging University of Cologne Kerpener Straße 62 50937 Cologne Germany
2. Institute of Neuroscience and Medicine Nuclear Chemistry (INM-5) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Straße 52428 Jülich Germany
3. Faculty of Mathematics and Natural Sciences Department of Chemistry Institute of Inorganic Chemistry University of Cologne Greinstr. 6 50939 Cologne Germany
4. Faculty of Medicine and University Hospital Cologne Department of Nuclear Medicine University of Cologne Kerpener Straße 62 50937 Cologne Germany