1. Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul 05505, Korea.
2. Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung 402, Taiwan.
3. School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung 402, Taiwan.
4. Department of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan.