[1] Tianjin Med Univ Gen Hosp, Dept Ultrasonog, Tianjin, Peoples R China
[2] Peoples Liberat Army Rocket Force, Dept Med Clin Lab, Gen Hosp, Beijing, Peoples R China
[3] Peking Univ, Dept Obstet & Gynecol, Reprod Med Ctr, Hosp 3, Beijing, Peoples R China
[4] Tianjin Med Univ Gen Hosp, Dept Rheumatol, Tianjin, Peoples R China