1. Department of Radiology, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia 010050, P.R. China
2. Department of Cardiology, Inner Mongolia People's Hospital, Hohhot, Inner Mongolia 010020, P.R. China
3. Department of Radiology, The Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China