作者单位:Univ Calif San Francisco, Dept Lab Med, San Francisco, CA USA[1]Univ Calif San Francisco, Dept Neurol, San Francisco, CA USA[2]Univ Calif San Francisco, Dept Med, 1001 Potrero Ave,UCSF Mailbox 0874, San Francisco, CA 94143 USA[3]Univ Calif San Francisco, Dept Radiol & Biomed Imaging, San Francisco, CA 94143 USA[4]