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