1. ICIS - CNR, Corso Stati Uniti 4, 35127 Padova, Italy, Laboratory of Nuclear Medicine, Department of Clinical & Experimental Medicine, University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy, and Forschungszentrum Rossendorf, Institut für Bioanorganische und Radiopharmazeutische Chemie, PF 510 119, D-01314 Dresden, Germany