1. Department of Radiology, Division of Neuroradiology, Henry Ford Hospital, Detroit, Michigan
2. Department of Neurosurgery, Henry Ford Hospital, Detroit, Michigan
3. Departments of Neurosurgery and Biostatistics and Research Epidemiology, Henry Ford Hospital, Detroit, Michigan
4. Robarts Research Institute, London, Ontario
5. Departments of Neurosurgery and Neurology, Henry Ford Hospital, Detroit, Michigan