[1] Univ Cape Town, Fac Hlth Sci, Dept Human Biol, Med Imaging Res Unit,Div Biomed Engn, Cape Town, South Africa
[2] Stellenbosch Univ, Tygerberg Childrens Hosp, Dept Paediat & Child Hlth, Family Clin Res Unit, Stellenbosch, South Africa
[3] Stellenbosch Univ, Fac Hlth Sci, Stellenbosch, South Africa
[4] Univ Cape Town, Fac Sci, Dept Stat Sci, Cape Town, South Africa
[5] Massachusetts Gen Hosp, Dept Radiol, AA Martinos Ctr Biomed Imaging, Boston, MA USA
[6] Harvard Univ, Harvard Med Sch, Dept Radiol, Boston, MA USA