[1] Univ Calif San Francisco, Dept Radiol & Biomed Imaging, San Francisco, CA USA
[2] Univ Calif San Francisco, Dept Neurol, San Francisco, CA USA
[3] Univ Calif San Francisco, Dept Neurol Surg, San Francisco, CA USA
[4] Univ Calif San Francisco, Dept Radiol & Biomed Imaging, 505 Parnassus Ave, San Francisco, CA 94143 USA