1. Division of Neurosurgery, Department of Surgery, University of Alberta Hospital, Mackenzie Health Sciences Centre, Edmonton, Alberta;
2. Division of Neuroradiology, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital, Montreal, Quebec;
3. Laboratory of Interventional Neuroradiology, Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital Research Centre, Montreal, Quebec;
4. Division of Neurosurgery, Department of Surgery, Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital, Quebec;
5. Department of Mathematics and Statistics, Université de Montréal, Montreal, Canada