Ob-Gyn Ultrasound Unit, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Ultrasound Obstet Gynecol. 2022 Mar;59(3):317-324. doi: 10.1002/uog.23691.
To provide a detailed description of the sonographic appearance and development of various fetal structures of the midbrain and hindbrain (MBHB) during the early second trimester, and to evaluate the impact of the frequency of the transvaginal sonography (TVS) transducer on the early recognition of these structures.
This was a retrospective analysis of three-dimensional volumetric datasets of the MBHB from apparently normal fetuses at 14-19 gestational weeks, acquired by TVS in the midsagittal view through the posterior fontanelle. Using a multiplanar approach, we measured the tectal thickness and length, aqueductal thickness, tegmental thickness and width and height of the Blake's pouch (BP) neck. In addition, we assessed the existence of early vermian fissures, the linear shape of the brainstem and the components of the fastigium. The correlation between gestational age according to last menstrual period and sonographic measurements of MBHB structures was evaluated using Pearson's correlation (r). A subanalysis was performed to assess the performance of a 5-9-MHz vs a 6-12-MHz TVS transducer in visualizing the MBHB structures in the early second trimester.
Sixty brain volumes were included in the study, obtained at a mean gestational age of 16.2 weeks (range, 14.1-19.0 weeks), with a transverse cerebellar diameter range of 13.0-19.8 mm. We found a strong correlation between gestational age and all MBHB measurements, with the exception of the tectal, tegmental and aqueductal thicknesses, for which the correlation was moderate. There was good-to-excellent intraobserver and moderate-to-good interobserver correlation for most MBHB measurements. We observed that the BP neck was patent in all fetuses between 14 and 18 weeks with decreasing diameter, and that the aqueductal thickness was significantly smaller at ≥ 18 weeks compared with at < 16 weeks. The early vermian fissures and the linear shape of the brainstem were present in all fetuses from 14 weeks. We found that, in the early second trimester, the horizontal arm of the presumed 'fastigium' evolves from the fourth ventricular choroid plexus and not the posterior vermis, indicating that this is not the fastigium. Standard- and high-resolution TVS transducers performed similarly in the assessment of MBHB anatomy.
Detailed early second-trimester assessment of the MBHB is feasible by transvaginal neurosonography and provides reference data which may help in the early detection of brain pathology involving the MBHB. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.
详细描述中脑和后脑（MBHB）在妊娠中期第二个月的超声表现和发育，并评估经阴道超声（TVS）换能器的频率对这些结构的早期识别的影响。
这是一项对 14-19 孕周时通过 TVS 在后囟门的正中矢状面获得的 MBHB 的三维容积数据集的回顾性分析。我们使用多平面方法测量了顶盖厚度和长度、导水管厚度、脑桥被盖厚度和宽度以及 Blake's 囊（BP）颈部的高度。此外，我们评估了早期蚓状裂、脑干的线性形状和穹窿顶的组成部分的存在。使用 Pearson 相关（r）评估根据末次月经的孕周与 MBHB 结构的超声测量值之间的相关性。进行了亚分析以评估 5-9-MHz 与 6-12-MHz TVS 换能器在可视化妊娠中期第二个月 MBHB 结构方面的性能。
研究纳入了 60 个脑体积，获得的平均胎龄为 16.2 周（范围为 14.1-19.0 周），小脑横径范围为 13.0-19.8mm。我们发现，除了顶盖、脑桥被盖和导水管的厚度之外，孕周与所有 MBHB 测量值之间存在很强的相关性，而与这些厚度的相关性为中度。对于大多数 MBHB 测量值，观察者内和观察者间的相关性均良好至优秀，而观察者间的相关性为中度至良好。我们观察到，14-18 周的所有胎儿的 BP 颈部均为开放状态，且直径逐渐减小，与 <16 周相比，≥18 周的导水管厚度明显较小。14 周时所有胎儿均可见早期蚓状裂和脑干的线性形状。我们发现，在妊娠中期第二个月，假定的“穹窿顶”的水平臂由第四脑室脉络丛演变而来，而不是由后蚓部演变而来，这表明这不是穹窿顶。标准和高分辨率 TVS 换能器在评估 MBHB 解剖结构方面表现相似。
经阴道神经超声可对中脑后脑进行详细的妊娠中期第二个月评估，并提供参考数据，可能有助于早期发现涉及 MBHB 的脑病理学。© 2021 年国际妇产科超声学会。
