二维横切面新方法对胎儿胼胝体结构异常的诊断价值

目的探讨二维横切面法所得正常参考值范围对胼胝体结构异常的诊断价值。 方法选择2018年6月至2020年7月在南方医科大学附属深圳妇幼保健院行产前超声检查并使用二维颅脑横切面法筛查20周至足月的670例正常胎儿（正常组），疑诊胼胝体结构异常并经产前/后磁共振检查、产后超声或尸体解剖证实的胎儿77例（异常组）。胼胝体结构异常组分为4组：完全缺如组、部分缺如组、变薄组和变短组。对所有胎儿进行横切面上胼胝体最大前后径、膝部左右径和前后径、体部左右径和前后径、压部左右径和前后径、膝部前角和后角、压部前角和后角的测量。采用非参数检验比较正常组与异常组参数的差异。绘制异常组与正常组所有测量参数的复合散点图。 结果670例正常组和77例异常组孕妇年龄和孕周比较［30（28，33）岁 vs 30（26，34）岁；28（24，32）周 vs 25（23，28）周］，差异均无统计学意义（P均＞0.05）。正常组中，横切面和正中矢状切面的显示率分别为100%、13.9%。而在异常组中，横切面和正中矢状切面的显示率分别为100%、62.3%。胼胝体异常组膝部前角及后角、压部前角及后角、膝部前后径、胼胝体最大前后径、膝部左右径、压部左右径、压部前后径、体部左右径和体部前后径测值均低于正常组［48.00°（0°，80.68°）vs（66.76°±10.79°）；44.00°（0°，79.30°）vs 65.10°（49.30°，83.00°）；41.90°（0°，69.37°）vs（64.31°±10.27°）；38.50°（0°，72.10°）vs（65.38°±11.65°）；0.21（0，0.40）cm vs（0.44±0.09）cm；1.10（0，2.78）cm vs 3.33（2.11，4.20）cm；1.18（0，2.23）cm vs 1.81（1.22，2.46）cm；1.21（0，2.20）cm vs（2.02±0.40）cm；0.18（0，0.35）cm vs 0.45（0.32，0.63）cm；0.42（0，1.01）cm vs 0.62（0.40，0.98）cm；0.75（0，1.87）cm vs（1.86±0.33）cm］，差异均具有统计学意义（Z=-8.959、-8.650、-9.839、-9.993、-12.812、-13.668、-7.343、-10.521、-12.145、-5.260、-14.034，P均＜0.001）。各异常组与正常组的复合散点图结果显示胼胝体最大前后径显著低于正常胎儿测值第5百分位线；胼胝体厚度变薄的发育不良组膝部和压部前后径明显低于正常胎儿测值第5百分位线，其他参数在复合散点图上差异不明显。 结论产前二维超声颅脑横切面法能较好地评估中晚孕期胎儿胼胝体异常相关结构的大小，对胼胝体结构异常胎儿的胼胝体大小评估具有参考价值，尤其是胼胝体最大前后径适用于绝大部分胼胝体结构异常评估，胼胝体膝部前后径及压部前后径对于胼胝体变薄型发育不良有参考价值，其他参数对胼胝体结构异常的诊断参考意义不大。

Diagnostic value of a new method by two-dimensional axial planes in fetal corpus callosum structural abnormalities

ObjectiveTo evaluate the diagnostic value of the normal reference range obtained by two-dimensional axial planes in abnormal fetal corpus callosum. MethodsBetween June 2018 and July 2020, 670 normal and 77 abnormal fetuses at a gestational age of 20 weeks to full term were evaluated by two-dimensional axial planes at Shenzhen Maternity & Child Healthcare Hospital, Southern Medical University. The diagnosis of abnormal fetuses was confirmed by pre-natal MRI/post-natal ultrasound/ autopsy examinations. The abnormal fetuses were divided into four groups: complete agenesis of the corpus callosum, partial agenesis of the corpus callosum, hypoplasia of the corpus callosum, and hypoplasia of the corpus callosum. The largest length of the corpus callosum, the anteroposterior and mediolateral diameters of the genu, body, and splenium, and anterior and posterior angles of the genu and splenium were measured. Non-parametric test was used to compare the parameters between the normal and abnormal groups, and compound scatter plots of all parameters were drawn. ResultsThere was no significant difference in maternal age 30 (28, 33) years vs 30 (26, 34) years] and gestational weeks 28 (24, 32) weeks vs 25 (23, 28) weeks] between the 670 normal pregnant women and the 77 abnormal pregnant women (P＞0.05). In the normal group, the success rate in obtaining satisfactory axial planes reached 100%, but it was only 13.9% in obtaining satisfactory sagittal planes in the normal group; the corresponding figures in the abnormal cases were 100% and 62.3%. The anterior and posterior angles of the genu, anterior and posterior angles of the splenium, anteroposterior diameter of the genu, the largest length of the corpus callosum, mediolateral diameter of the genu, anteroposterior diameter of the splenium, anteroposterior diameter of the splenium, mediolateral diameter of the body, and anteroposterior diameter of the body in the abnormal group were significantly lower than those in the normal group 48.00° (0°, 80.68°) vs (66.76°±10.79°); 44.00° (0°, 79.30°) vs 65.10° (49.30°, 83.00°); 41.90° (0°, 69.37°) vs (64.31°±10.27°); 38.50° (0°, 72.10°) vs (65.38°±11.65°); 0.21 (0, 0.40) cm vs (0.44±0.09) cm; 1.10 (0, 2.78) cm vs 3.33 (2.11, 4.20) cm; 1.18 (0, 2.23) cm vs 1.81 (1.22, 2.46) cm; 1.21 (0, 2.20) cm vs (2.02±0.40) cm; 0.18 (0, 0.35) cm vs 0.45 (0.32, 0.63) cm; 0.42 (0, 1.01) cm vs 0.62 (0.40, 0.98) cm; and 0.75 (0, 1.87) cm vs (1.86±0.33) cm, respectively] (Z=-8.959, -8.650, -9.839, -9.993, -12.812, -13.668, -7.343, -10.521, -12.145, -5.260, and -14.034, respectively, P＜0.001). The compound scatter plots showed that the largest length of the corpus callosum was significantly shorter, and the thickness of the genu and splenium with HpCC (thin) was significantly lower in abnormal fetuses than in normal fetuses, showing the parameter measurements below the 5th percentile line of normal values. There was no significant difference in other parameters on the compound scatter plots. ConclusionPrenatal two-dimensional axial planes can well evaluate the corpus callosum structure, which is valuable for the evaluation of fetuses with abnormal corpus callosum. In particular, the largest length of the corpus callosum is suitable for the evaluation of most abnormal corpus callosum cases. The anteroposterior diameters of the genu and splenium are useful for the diagnosis of HpCC (thin). Other parameters are of little significance for the diagnosis of corpus callosum abnormalities.