1. Department of Radiology, College of Medicine, Korea University, Seoul 136-705, Korea.
2. Department of Radiology, College of Medicine, Kangwon National University, Kangwon-do 200-947, Korea.
3. Department of General Thoracic and Cardiovascular Surgery, College of Medicine, Korea University, Seoul 136-705, Korea.
4. Department of Internal Medicine, College of Medicine, Korea University, Seoul 136-705, Korea.