Centre d'Echographies Ambroise Paré Les Mureaux, CHI Poissy Saint-Germain, Yvelines, France.
Ultrasound Obstet Gynecol. 2011 May;37(5):570-5. doi: 10.1002/uog.8847.
To construct reference ranges for fetal optic tract mean diameter and to report measurements in fetuses with agenesis of the septum pellucidum (SP).
Three-dimensional volumes of the optic chiasm were acquired in 98 normal fetuses during routine sonographic examination at 21-36 weeks' gestation and the diameters of the posterior left and right optic tracts were measured offline. A polynomial regression approach (mean and SD model) was used to compute reference charts for the mean fetal optic tract diameter measurements. In addition, 23 volumes were acquired in fetuses with SP agenesis for offline measurement of optic tract diameter. Complete follow-up was obtained in 13 of these 23 cases.
In normal fetuses, the optic tract diameter increased linearly throughout gestation. There was no evidence of increased variability with gestational age (constant SD). Normal charts and equations for Z-score calculation were constructed. Among the 13 fetuses with SP agenesis and complete follow-up, nine had normal measurements, of which eight had normal vision postnatally. Four had hypoplastic optic tract, defined as mean optic tract diameter Z-score below - 3. Of these, two underwent termination of pregnancy and pathological examination confirmed hypoplasia of the tract, one showed signs of hypoplasia at magnetic resonance imaging and postnatal examination confirmed blindness, and one had a hypoplastic measurement for only one tract and was born with poor vision and abnormal bilateral eye movements.
We present new reference charts for mean fetal optic tract 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 in prenatal counseling.
构建胎儿视束平均直径的参考范围，并报告透明隔发育不全（SP）胎儿的测量值。
在 21-36 孕周的常规超声检查中，对 98 例正常胎儿的视交叉进行三维容积采集，并离线测量左、右视束后直径。采用多项式回归方法（均值和标准差模型）计算平均胎儿视束直径测量的参考图表。此外，在 SP 发育不全的胎儿中采集 23 个容积，用于离线测量视束直径。在这 23 例中，有 13 例获得了完整的随访。
在正常胎儿中，视束直径在整个妊娠期间呈线性增长。没有证据表明随胎龄增加而变异增加（SD 不变）。构建了正常图表和 Z 分数计算方程。在 13 例 SP 发育不全且完整随访的胎儿中，9 例测量值正常，其中 8 例出生后视力正常。4 例视束发育不良，定义为视束平均直径 Z 分数低于-3。其中，2 例终止妊娠，病理检查证实视束发育不良，1 例磁共振成像和产后检查显示视束发育不良迹象，证实失明，1 例仅一侧视束发育不良，出生时视力差，双眼运动异常。
我们提出了新的胎儿视束平均直径参考图表。在 SP 发育不全的胎儿中，视束超声检查可能是评估其发育的有用工具，并有助于产前咨询。
