1. Department of Surgery, Division of Neurosurgery, National University Hospital, Singapore, Singapore
2. Jiro Suzuki Memorial Gamma House, Furukawa Seiryo Hospital, Furukawa, Japan
3. Department of Neurosurgery, Veterans General Hospital, Taipei, Taiwan
4. National Yang-Ming University, Taipei, Taiwan
5. Katsuta Hospital Mito GammaHouse, Ibaraki, Japan
6. Ruber International Hospital, Madrid, Spain
7. St Elizabeth Ziekenhuis, Tilburg, the Netherlands
8. Department of Neuroradiology, Karolinska Hospital, Stockholm, Sweden