Hye Sun Park1, Jung Hwan Baek2, Auh Whan Park3. 1. Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. 2. Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. radbaek@naver.com. 3. Vascular & Interventional Radiology Section, Department of Radiology, University of Virginia Health System, 1215 Lee Street, Charlottesville, VA, 22908-0170, USA.