1. Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
2. Division of Neurointerventional Radiology, Neuroscience Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
3. Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
4. Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
5. Neuroscience Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA