[1] Keio Univ, Sch Med, Dept Neurosurg, Shinjuku Ku, 35 Shinanomachi, Tokyo 1608582, Japan
[2] Keio Univ, Sch Med, Dept Pathol, Shinjuku Ku, 35 Shinanomachi, Tokyo 1608582, Japan
[3] Keio Univ, Sch Med, Dept Diagnost Radiol, Shinjuku Ku, 35 Shinanomachi, Tokyo 1608582, Japan