1. Department of Ultrasound, Chinese PLA General Hospital, Beijing 100853, P.R. China
2. Department of Ultrasound, General Hospital of Beijing Military Region, Beijing 100700, P.R. China
3. Department of Hepatobiliary Surgery, Chinese PLA General Hospital, Beijing 100853, P.R. China
4. Department of Ultrasound, 161st Hospital of Chinese PLA, Wuhan, Hubei 430010, P.R. China
5. Department of Pharmaceutics, Beijing Institute of Pharmacology and Toxicology, Beijing 100039, P.R. China