1. Department of Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center; Seoul, South Korea
2. Department of Radiology, Kwandong University College of Medicine, Myongji Hospital; Goyang, South Korea
3. Departments of Neurosurgery, Seoul National University College of Medicine; Seoul, South Korea
4. Radiology, Seoul National University College of Medicine; Seoul, South Korea