1. From the Departments of Neurosurgery (S.K., D.K., K. Houkin) and Nuclear Medicine (K. Hirata, T.S., N.T.), Hokkaido University Graduate School of Medicine, Sapporo, Japan; and Department of Neurosurgery, Graduate School of Medicine and Pharmaceutical Science, University of Toyama, Toyama, Japan (S.K., D.K.).