1. Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Radiology, Presbyterian Medical Center, Jeonju, Korea.
3. Department of Anesthesiology and Pain Medicine, Presbyterian Medical Center, Jeonju, Korea.
4. Department of Preventive Medicine, Chonbuk National University Medical School, Jeonju, Korea.