1. Division of Diagnostic and Therapeutic Neuroradiology, St. Michael's Hospital, Toronto, Ontario, Canada
2. Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
3. Department of Medical Imaging, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
4. Department of Neurosurgery, University of Alabama at Birmingham, Alabama
5. Department of Neurosurgery, State University of New York at Buffalo, Buffalo, New York
6. Department of Interventional Neuroradiology, University of Florence, Florence, Italy
7. Department of Diagnostic and Therapeutic Neuroradiology, Toulouse University Hospital, Toulouse, France
8. Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut