1. Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Clinical Radiology, University of Muenster, Muenster, Germany
3. Institute of Neuroradiology, University Medical Center Schleswig Holstein, Lübeck, Germany
4. Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
5. Department of Neurology, University of Muenster, Muenster, Germany
6. Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
7. Department of Neuroradiology, Asklepios Hospital Altona, Hamburg, Germany
8. Department of Neuroradiology, University of Medicine Goettingen, Goettingen, Germany
9. Institute of Diagnostic Radiology and Neuroradiology, University of Medicine Greifswald, Greifswald, Germany.