[1] Univ Hosp Cologne, Dept Neurol, Kerpener Str 62, D-50937 Cologne, Germany
[2] Univ Hosp Cologne, Dept Clin Chem, Cologne, Germany
[3] Univ Hosp Cologne, Neuroradiol Sect, Dept Radiol, Cologne, Germany
[4] Res Ctr Julich, Cognit Neurosci, Inst Neurosci & Med INM 3, Julich, Germany
[5] Univ Hosp Aachen, Dept Neuroradiol, Aachen, Germany