Bo Gao1, Cui Lv2. 1. Department of Radiology, Yantai Yuhuangding Hospital, Yantai 264000, Shandong Province, People's Republic of China. Electronic address: gygb2004@163.com. 2. Department of Neurology, Yantai City Yantaishan Hospital, Shandong Province, People's Republic of China.