1. Contribution from the Department of Life Science, Gwangju Institute of Science and Technology (GIST), 1 Oryoung-dong, Buk-gu, Gwangju 500-712, Republic of Korea, Institute for Science and Technology in Medicine, Keele University, Thronburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB United Kingdom, and Department of Diagnostic Radiology, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea