1. Department of Nuclear Medicine, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
2. Department of Radiology, Shougang Shuigang Hospital, Liupanshui, Guizhou 553000, P.R. China
3. Department of Obstetrics, Zunyi Hospital of Traditional Chinese Medicine, Zunyi, Guizhou 563000, P.R. China