[1] Hannover Med Sch, Dept Neurol, D-3000 Hannover, Germany
[2] Hannover Med Sch, Integrated Res & Treatment Ctr Transplantat, D-3000 Hannover, Germany
[3] Hannover Med Sch, Dept Diagnost & Intervent Neuroradiol, D-3000 Hannover, Germany
[4] Duke Univ, Duke Clin Res Inst, Durham, NC 27705 USA