1. Department of Radiology , Brigham and Womens Hospital , Boston , MA 02115 , USA
2. Department of Neurology, St. Josef-Hospital , Ruhr Universität Bochum , 44791 Bochum , Germany
3. Department of Health Economics, Policy and Management , Karolinska Institutet , 171 77 Stockholm , Sweden
4. Department of Biology , University of Patras , 265 04 Patras , Greece
5. Department of Radiology , Universitätsspital Zürich , 8091 Zürich , Switzerland
6. First Department of Radiology, School of Medicine , National & Kapodistrian University of Athens, Areteion Hospital , 115 28 Athens , Greece
7. Department of Diagnostic and Interventional Neuroradiology , Hospital Bremen-Mitte/Bremen-Ost , 28205 Bremen , Germany