title: Preface.
authors.affiliation: Nuclear Medicine, S. Orsola-Malpighi Polyclinic, University of Bologna, Bologna, Italy. Electronic address: stefano.fanti@aosp.bo.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fanti
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA. Electronic address: Abass.alavi@uphs.upenn.edu.
authors.forename: Abass
authors.initials: A
authors.lastname: Alavi