1. Department of Diagnostic and Interventional Radiology, University Hospital Ulm , Ulm, Germany
2. Section of Neuroradiology, University of Ulm, Bezirkskrankenhaus Guenzburg , Guenzburg, Germany
3. Institute of Neuroradiology, Ludwig-Maximilian-University , Munich, Germany
4. Department of Neurosurgery, University of Ulm, Bezirkskrankenhaus Guenzburg , Guenzburg, Germany