1 Department of Neurological Surgery, University of California San Francisco and San Francisco General Hospital, San Francisco, CA, USA; Brain and Spinal Injury Center, San Francisco General Hospital, San Francisco, CA, USA.
2 Department of Radiology and Biomedical Imaging, University of California San Francisco and San Francisco General Hospital, San Francisco, CA, USA.
3 Department of Radiology and Biomedical Imaging, University of California San Francisco and San Francisco General Hospital, San Francisco, CA, USA; Brain and Spinal Injury Center, San Francisco General Hospital, San Francisco, CA, USA.