1 Department of Ultrasound, Affiliate Hospital of Sichuan Nursing Vocational College, The Third People's Hospital of Sichuan Province, Chengdu, Sichuan, China; Department of Ultrasound, Xiaojin County People's Hospital, Xiaojin County, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan, China.
2 Department of Pediatric Surgery, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, China. Electronic address: zhangyb_chengdu@foxmail.com.
3 Department of Ultrasound, Xiaojin County People's Hospital, Xiaojin County, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan, China.