Measurement of fetal optic tract diameters with three-dimensional ultrasound / 中国医师杂志

ABSTRACT

Objectives To construct reference range of fetal optic tract mean diameter and to report the measured optic tract mean diameter in fetuses with agenesis of the septum pellucidum (SP).Methods Three-dimensional volumes of the optic chiasm were acquired in 254 normal fetuses during routine sonographic examination at 21 ～ 40 weeks' gestation and the diameters of posterior left and right optic tracts were measured offline.A polynomial regression approach was used to calculate reference charts for the fetal optic tract mean diameter.In addition,16 three-dimensional volumes were acquired in fetuses with SP agenesis for offline measurement of optic tract diameter.The complete follow-up data were obtained in 7 of these 16 cases.Results In normal fetuses,the optic tract diameter increased linearly throughout gestation.Normal charts and equations were constructed.Among 7 fetuses with SP agenesis and complete follow-up,one had postnatal normal vision,two had hypoplastic optic tract,and four underwent termination of pregnancy.Three cases of normal childbirth were tested after the baby was born as a bundle of apparent dysplasia,including 1 case of neonatal characterized by lack of vision at the one year old and 2 cases of impaired vision.Four cases of termination of pregnancy included 1 case with tracking pathological confirmation of optic nerve hypoplasia,and the other 3 cases without tracking the pathological results.Conclusions We present new reference charts for fetal optic tract mean diameter.In fetuses with agenesis of the SP,sonography of the optic tract might be a useful tool to assess its development and may help prenatal counseling.