1. Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Institute of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
3. Department of Radiology, Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
4. Department of Neuroradiology, University of Rostock, Rostock, Germany
5. Department of Neuroradiology, University Hospital Schleswig-Holstein, Luebeck, Germany
6. Department of Neurology, University Hospital Münster, Münster, Germany