1. Department of Radiology, Ewha Womans University College of Medicine, Seoul, Korea.
2. Department of Radiology and Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.