中文摘要：

目的初步研究胎儿视交叉及其前后视神经和视束大小，创建产前超声对胎儿视神经、视交叉及视束的显示与测量方法以及正常参考值范围。方法利用高分辨率二维超声在显示颅底动脉环切面基础上旋转探头显示视交叉平面，在此切面上分别测量453例正常胎儿的双侧视神经直径、视交叉横径、视交叉面积和双侧视束直径。以孕周及相应生物学参数为自变量建立各测值的回归方程并分析各测值的性别差异。结果视交叉切面于孕26~33周显示较好；除外视交叉面积，此测量方式重复性好，两观察者间差异无统计学意义（P〉0．05）。各测值包括左右侧视神经、左右侧视束、视交叉横径与面积均随孕周的增大呈线性增粗（r=0．952，0．95，0．807，0．906），左右侧视神经、左右侧视束差异无统计学意义（P〉0．05）。胎儿视神经、视束及视交叉各项测值间性别差异无统计学意义（P〉0．05）。结论产前超声可以较好地观察与评估胎儿视交叉、视神经和视束的形态与大小，利用高分辨率超声制定的正常参考值范围能为产前视交叉段视路异常提供影像学参考。

英文摘要：

Objective To research fetal optic nerve, optic chiasma and optic tract size using high resolution prenatal ultrasound, establish a scan method and the reference range of optic nerve, optic chiasma and optic tract in normal fetus. Methods Based on the section of circulus arteriosus cerebri, the probe were rotated to get the chiasma section for measuring the diameter of bilateral optic nerve, optic tract and area of optic chiasma in 453 normal fetus respectively. Used gestation age and corresponding biological parameters as independent variables, the regression equation was established analyse the gender differences. Results 26- 33 weeks was the preferable gestational age to visualize the chiasma section. It had good repeatability except chiasma area. The bilateral optic nerve and optic tract diameter, optic ehiasma diameter and area had an increased along with the gestational age reposefully. There was no significant difference between the two sides of optic nerve and the gender. Conclusions Prenatal ultrasound can assess the size and shape of fetal optic nerve, optic chiasma and optic tract. The normal reference range, established by ultrasound, is helpful to diagnose the abnormality of optic ehiasma.