1. Department of Radiology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan 15355, Korea.
2. Department of Pulmonology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan 15355, Korea.
3. Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul 08308, Korea.
4. Department of Radiology, Korea University Anam Hospital, Korea University College of Medicine, Seoul 02841, Korea.
5. Medical Science Research Center, Korea University Ansan Hospital, Korea University College of Medicine, Ansan 15355, Korea.