[1] Univ Toronto, Hosp Sick Children, Dept Diagnost Imaging, Toronto, ON M5G 1X8, Canada
[2] Sungkyunkwan Univ, Samsung Cheil Hosp, Dept Ultrasound, Chungku, South Korea
[3] Sungkyunkwan Univ, Womens Healthcare Ctr, Chungku, South Korea
[4] Univ Ulsan, Asan Med Ctr, Dept Diagnost Radiol, Seoul, South Korea
[5] Chungbuk Natl Univ Hosp, Dept Diagnost Radiol, Chungbuk, South Korea