1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 2Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland, 3Department of Radiology, University Hospital Lausanne (CHUV), Lausanne, Switzerland, 4Department of Electrical Engineering (LTS5), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 5Department of Physics and Astronomy, University of Bonn, Bonn, Germany