[1] Johns Hopkins Univ, Russell H Morgan Dept Radiol & Radiol Sci, Sch Med, 601 North Caroline St,JHOC 3rd Floor, Baltimore, MD 21287 USA
[2] Johns Hopkins Univ, Sch Med, Dept Neurol, Baltimore, MD 21205 USA
[3] Johns Hopkins Univ, Sch Med, Dept Neurosurg, Baltimore, MD 21205 USA
[4] Johns Hopkins Univ, Sch Med, Dept Orthopaed Surg, Baltimore, MD USA
[5] Johns Hopkins Univ, Sch Med, Dept Oncol, Baltimore, MD 21205 USA