1. Department of Neurosurgery, Stanford University, Stanford, California, USA
2. Department of Radiology, Stanford University, Stanford, California, USA
3. Department of Neurosurgery, University of Utah, Salt Lake City, Utah, USA
4. Department of Radiology, Tehran University of Medical Sciences, Tehran, Iran
5. Stanford School of Medicine, Stanford University, Stanford, California, USA
6. Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota, USA