1. Department of Medical Imaging, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266001, P.R. China
2. Department of Medical Imaging, People's Hospital of Rizhao, Rizhao, Shandong 276800, P.R. China
3. ICU, People's Hospital of Zhangqiu, Jinan, Shandong 250000, P.R. China