评估三维超声自动容积导航技术（Smart Planes）与二维超声在获取胎儿颅脑正中矢状面（MSP）以及测量胎儿胼胝体及小脑蚓部参数的一致性和可重复性。

选取2017年10月至2017年12月在广东省妇幼保健院行产前超声检查的单胎妊娠孕妇168名作为研究对象。采用二维超声获取胎儿颅脑MSP并手动测量胼胝体前后径，测量小脑蚓部前后径、上下径及面积。随后应用三维容积探头获取胎儿颅脑容积数据，利用Smart Planes技术自动分析并测量胼胝体和小脑的相应数据。采用组内相关系数（ICC）及Bland-Altman法比较二维超声与Smart Planes技术对胎儿胼胝体以及小脑蚓部的测量的一致性和可重复性。对比不同操作者间测量的一致性及同一操作者采用两种方法测量的用时差异。

采用Smart Planes技术与二维超声获取胎儿颅脑MSP的成功率分别为97.0％（163/168）、79.8%（134/168），差异有统计学意义（χ²=24.40，P<0.001）。其中76.8%（129/168）胎儿通过二维超声及Smart Planes技术均获得颅脑MSP并测量相关参数。比较二维超声与Smart Planes技术测量胼胝体前后径以及小脑蚓部前后径、上下径、面积的一致性，ICC分别为0.972、0.968、0.946、0.967。比较同一位操作者采用Smart Planes技术2次测量的一致性，ICC分别为0.995、0.987、0.962、0.993。比较不同操作者间采用Smart Planes技术测量的一致性，ICC分别为0.986、0.966、0.972、0.955。采用Smart Planes技术获取胎儿颅脑MSP所需时间[（13.49±5.38）s]明显短于采用二维超声所需时间[（89.99±113.42）s]，差异有统计学意义（U=587.50，Z=-12.915，P<0.001）。

三维超声自动容积导航技术可快速获取胎儿颅脑MSP，测量所得胼胝体及小脑蚓部的参数与二维超声测量所得结果一致性较好，有助于超声医师对胎儿中线结构做出快速准确的识别和测量。

To evaluate the consistency and reproducibility of the automatic volumetric navigation technology (Smart Planes) of three-dimensional ultrasound compared with two-dimensional ultrasound in obtaining the median sagittal plane (MSP) of the fetal brain and cerebellum, and in measuring the parameters of the fetal corpus callosum and cerebellar vermis.

This study, conducted at the Department of Ultrasound of Guangdong Women and Children′s Hospital from October 2017 to December 2017, enrolled 168 patients with singleton pregnancy undergoing routine pregnancy examination. Two-dimensional ultrasound was used to obtain the MSP of fetal brain and cerebellum, and four parameters including the anteroposterior diameter of the corpus callosum and the anteroposterior diameter, craniocaudal diameter, and area of the cerebellar vermis were measured manually. Then, a three-dimensional volume probe was used to obtain fetal brain volume data, and Smart Planes technology was used to automatically measuring those four parameters. The consistency and reproducibility between the two methods were assessed by interclass correlation coefficients (ICCs) and Bland–Altman plots, and the difference in the measurements of fetal corpus callosum and cerebellar vermis acquired by the two methods was also compared. Furthermore, the interobserver variability of Smart Planes technology measurement was calculated and the acquisition time difference between the two methods was compared.

The MSP of the fetal brain and cerebellum was successfully reconstructed in 97.0% (163/168) of the fetuses by Smart Planes technology, and in 79.8% (134/168) by two-dimensional ultrasound, which showed a statistical difference (P<0.001). The fetal MSP of the brain and cerebellum as well as the relevant parameters were obtained successfully by both methods in 76.8% (129/168) of fetuses. Comparing the measurements of Smart Planes with two-dimensional ultrasound, ICCs of the anteroposterior diameter of the corpus callosum and the anteroposterior diameter, craniocaudal diameter, and area of cerebellar vermis were 0.972, 0.986, 0.946, and 0.967, respectively. The ICCs of intraobserver variability for measurements of Smart Planes were 0.995, 0.987, 0.962, and 0.993, respectively, and the corresponding values for measurements of Smart Planes were 0.986, 0.966, 0.972, and 0.955, respectively. The acquisition time of the MSP by Smart Planes was (13.49±5.38) s, which was significantly shorter than that of two-dimensional ultrasound [(89.99±113.42) s; U=587.50, z=-12.915, P<0.001).

Smart Planes allows to obtain the MSP of fetal brain and cerebellum in a shorter time. The measurements of the corpus callosum and cerebellar vermis obtained by Smart Planes show a good agreement with those of two-dimensional ultrasound, which will result in faster and more accurate recognition and measurement of fetal midline structure by sonographers.