1 Department of Radiology, University of British Columbia, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada. Electronic address: tyan7@student.ubc.ca.
2 Division of Cardiac Surgery, Department of Surgery, University of British Columbia, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada.
3 Division of Neurosurgery, Department of Surgery, University of British Columbia, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada.
4 Division of Neurology, Department of Medicine, University of British Columbia, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada.
5 Department of Radiology, University of British Columbia, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada.