1. Clinic for Diagnostic and Interventional Neuroradiology, University Clinic Bonn, and German Center for Neurodegenerative Diseases, DZNE, Bonn, Germany
2. Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
3. Department of Radiology, Stanford University, Stanford, CA
4. Centre for Medical Sciences, University of Trento, Trento, Italy.