1. Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne University of Cologne Cologne Germany
2. Department of General Neurosurgery, Center for Neurosurgery, Faculty of Medicine and University Hospital Cologne University of Cologne Cologne Germany
3. Philips GmbH Innovative Technologies Aachen Germany
4. Department of Stereotaxy and Functional Neurosurgery, Center for Neurosurgery, Faculty of Medicine and University Hospital Cologne University of Cologne Cologne Germany
5. Department of Radiology University Hospitals Cleveland Medical Center Cleveland Ohio USA
6. Department of Radiology Case Western Reserve University Cleveland Cleveland Ohio USA