1. Departments of Radiology & Imaging Sciences and Neurosurgery, University of Utah, Salt Lake City, Utah
2. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
3. Department of Radiology, University of Washington, Seattle, Washington
4. Departments of Radiology and Neurosurgery, Columbia University College of Physicians & Surgeons, New York, New York