1. Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
2. Department of Radiology, Kyung Hee University Hospital at Gangdong, School of Medicine, Kyung Hee University, Seoul 134-727, Korea.
3. Department of Microbiology, Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul 138-736, Korea.