Objectives The present study was performed to examine the utility of a new first trimester marker called the “brain angle” (BA) in screening for trisomy 21. We postulate that differences in the midbrain anatomy between euploid fetuses and those that are affected by trisomy 21 are reflected in changes in BA measurements. Methods In fetuses at 11+0–13+6 weeks of gestations, which were at high risk for trisomy 21, the angle was measured between the line crossing the thalamus and mesencephalon cranial border tangentially and the line crossing the brainstem lower limit. This angle was compared between fetuses with trisomy 21 (based on karyotyping) and those with a normal karyotype. Results Trisomy 21 was detected in 45 (8%) of 560 fetuses. Receiver operating characteristic analysis showed that, at BA≥94°, the sensitivity and specificity for determining trisomy 21 were 97.8% (95% CI=88.2–99.9%) and 100% (95% CI=99.2–100%), respectively. Conclusions Fetal BA appears to be a promising new first trimester marker in screening for trisomy 21.

中文翻译：

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孕早期21三体筛查新方法：胎儿脑角

目的 本研究旨在检验称为“脑角”(BA) 的新妊娠早期标志物在筛查 21 三体中的效用。我们假设整倍体胎儿和受 21 三体影响的胎儿在中脑解剖结构上存在差异反映在 BA 测量值的变化中。方法 在 11 岁的胎儿中+0–13+6妊娠数周，21 三体的高风险，测量穿过丘脑和中脑颅缘切线的线与穿过脑干下限的线之间的角度。该角度在 21 三体（基于核型分析）和正常核型胎儿之间进行了比较。结果 560 个胎儿中有 45 个 (8%) 检测到 21 三体。受试者工作特征分析表明，在 BA≥94° 时，确定 21 三体的敏感性和特异性分别为 97.8%（95% CI=88.2-99.9%）和 100%（95% CI=99.2-100%）。结论 胎儿 BA 似乎是筛查 21 三体的有希望的新的早孕标志物。