1. Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto Western Hospital; Toronto, Ontario, Canada
2. Service de Neuroradiologie Diagnostique et Thérapeutique, Hôpital de Bicetre, Le Kremlin-Bicetre; Paris, France
3. Department of Neuroradiology, University Hospital Aachen; Aachen, Germany
4. Department of Diagnostic Radiology, the Hospital for Sick Children, University of Toronto; Toronto, Ontario, Canada
5. Clinic for Neurosurgery, University Hospital Aachen; Aachen Germany