1. Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
2. Department of Neurological Surgery, University of Washington School of Medicine, Seattle, WA, USA
3. Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
4. St. Paul Radiology, St. Paul, MN, USA
5. Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA