[1] Fourth Mil Med Univ, Xijing Hosp, Dept Anesthesiol, Xian 710032, Peoples R China
[2] Fourth Mil Med Univ, Xijing Cardiovasc Hosp, Xian 710032, Peoples R China
[3] Fourth Mil Med Univ, Dept Hlth Stat, Xian 710032, Peoples R China
[4] Fourth Mil Med Univ, Xijing Hosp, Dept Ultrasound Diag, Xian 710032, Peoples R China
[5] Fourth Mil Med Univ, Xijing Hosp, Dept Radiol, Xian 710032, Peoples R China