1. Department of Radiology, Chonnam National University Medical School, Gwangju 501-757, Korea.
2. Center for Aging and Geriatrics, Chonnam National University Medical School, Gwangju 501-757, Korea.
3. Department of Radiology, Chonnam National University Hospital, Gwangju 501-757, Korea.
4. Department of Surgery, Chonnam National University Medical School, Gwangju 501-757, Korea.