1 Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, 399 Bathurst St, ON M5T 2S8, Toronto, Ontario, Canada. seantoreilly@doctors.org.uk.
2 Department of Neuroradiology, Royal Victoria Hospital, Belfast, County Antrim, UK. seantoreilly@doctors.org.uk.
3 Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, 399 Bathurst St, ON M5T 2S8, Toronto, Ontario, Canada.
4 Department of Neurosurgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.