1. Department of Radiology, Seoul National University College of Medicine, SNU-SMG Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 156-707, Republic of Korea
2. Plasma Bioscience Research Center, Kwangwoon University, 20 Kwangwoon-gil, Nowon-Gu, Seoul139-701, Republic of Korea