1. Division of Neuroradiology, Department of Radiology, Dalhousie University & Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
2. Division of Neurology, Department of Medicine, Dalhousie University & Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
3. Queen Elizabeth II Health Sciences Centre, Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
4. Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada