[1] Aarhus Univ, Inst Clin Med, Dept Nucl Med, Aarhus, Denmark
[2] Imperial Coll London, Dept Med, London, England
[3] Newcastle Univ, Div Neurol, Newcastle Upon Tyne, Tyne & Wear, England
[4] Azienda Osped, Dept Neurol, Perugia, Italy
[5] Univ Perugia, Perugia, Italy