1. Institute of Radiochemistry & Experimental Molecular Imaging; University Clinic Cologne; Kerpener Str. 62 50937 Cologne Germany
2. Max Planck Institute for Metabolism Research; Gleueler Str. 50 50931 Cologne Germany
3. Clinic of Nuclear Medicine; RWTH Aachen University; Pauwelsstraße 30 52074 Aachen Germany
4. Institute of Organic & Biomolecular Chemistry; Georg-August University; Tammannstr. 2 37077 Göttingen Germany
5. Department of Nuclear Medicine; Maastricht University Medical Center; PO Box 616 6200 MD Maastricht The Netherlands