1. Departments of Radiology and Medical Imaging and
2. Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;
3. Advocate Neurovascular Center, Oak Lawn, Illinois;
4. Borgess Brain & Spine Institute, Kalamazoo, Michigan;
5. Department of Neurological Surgery, Tulane University, New Orleans, Louisiana; and
6. Crouse Radiology Associates Medical Imaging, Syracuse, New York