| Authors: |
Su XR; Ultrasound Medicine Center, Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital), Lanzhou, Gansu Province, 730050, PR China., Li TG; Ultrasound Medicine Center, Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital), Lanzhou, Gansu Province, 730050, PR China. litiangang1981@126.com., Yao X; Ultrasound Medicine Center, Longxi County Maternity and Child-care Hospital, Longxi, Gansu Province, 748199, PR China., Zhang WD; Ultrasound Medicine Center, Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital), Lanzhou, Gansu Province, 730050, PR China., Li XY; Ultrasound Medicine Center, Longxi County Maternity and Child-care Hospital, Longxi, Gansu Province, 748199, PR China. |