Sally F. Barrington, Consultant Physician in Nuclear Medicine at the PET Imaging Centre at St. Thomas', Guy's, King's & St. Thomas' School of Medicine, London, UK Michael N. Maisey, Emeritus Professor of Radiological Sciences, King's College, London, UK Richard L. Wahl, Professor of Radiology and Oncology, Director, Division of Nuclear Medicine/PET, Henry N. Wagner Professor of Nuclear Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA