1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea.
2. Department of Radiology, Pusan National University Hospital, Pusan National University School of Medicine and Medical Research Institute, Pusan 612-617, Korea.
3. Korean Institute of Tuberculosis, Seoul 121-150, Korea.
4. Korea Centers for Disease Control and Prevention, Seoul 122-701, Korea.
5. Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea.