-
Prefrontal space ratio: comparison between trisomy 21 and euploid fetuses in the second trimester.
Sonek J, Molina F, Hiett AK, Glover M, McKenna D, Nicolaides KH.
Ultrasound Obstet Gynecol 2012;40:293-6. -
Femur and humerus length in trisomy 21 fetuses at 11-14 weeks of gestation.
Longo D, DeFigueiredo D, Cicero S, Sacchini C, Nicolaides KH.
Ultrasound Obstet Gynecol 2004;23:143-7.