1. Department of Radiology and Biomedical Imaging, University of California San Francisco and San Francisco General Hospital, San Francisco, California.
2. Brain and Spinal Injury Center, San Francisco General Hospital, San Francisco, California.
3. Department of Emergency Medicine, University of California San Francisco and San Francisco General Hospital, San Francisco, California.
4. Department of Neurological Surgery, University of California San Francisco and San Francisco General Hospital, San Francisco, California.
5. Department of Anesthesia and Perioperative Care, University of California San Francisco and San Francisco General Hospital, San Francisco, California.
6. San Francisco Veteran's Affairs Medical Center, San Francisco, California.