[1] Tufts Med Ctr, Floating Hosp Children, Dept Pediat, Boston, MA USA
[2] Tufts Univ, Sch Med, Dept Pediat, Boston, MA 02111 USA
[3] Childrens Hosp Philadelphia, Dept Pediat, Philadelphia, PA 19104 USA
[4] Childrens Hosp Philadelphia, Dept Radiol, Philadelphia, PA 19104 USA
[5] Univ Penn, Dept Pediat, Perelman Sch Med, Philadelphia, PA 19104 USA
[6] Univ Penn, Dept Radiol, Perelman Sch Med, Philadelphia, PA 19104 USA
[7] Univ Manitoba, Dept Pediat & Child Hlth, Winnipeg, MB R3T 2N2, Canada
[8] Manitoba Inst Child Hlth, Winnipeg, MB, Canada