Ghassemi Neda, Rupe Eric, Perez Mishella, Lamale-Smith Leah, Fratto Victoria M, Farid Nikdokht, Hahn Michael, Ramos Gladys A, Ho Yoona, Rakow-Penner Rebecca, Horton Katelyn, Khan Sohini, Jones Marilyn, Pretorius Dolores H
University of California, San Diego, School of Medicine (N.G.).
University of California, San Diego, Maternal-Fetal Care and Genetics (M.P., L.L.-S., V.M.F., M.H., G.A.R., M.J., D.H.P.), USA.
J Ultrasound Med. 2020 Dec;39(12):2389-2403. doi: 10.1002/jum.15348. Epub 2020 Jun 29.
We hypothesized that: (1) fetal frontal horn (FH) morphology and their proximity to the cavum septi pellucidi (CSP) can assist in suspecting complete agenesis of the corpus callosum (cACC) and partial agenesis of the corpus callosum (pACC) earlier than known indirect ultrasound (US) findings; (2) FHs assist in differentiating a true CSP from a pseudocavum; and (3) magnetic resonance imaging (MRI) is useful in learning FH morphology and pseudocavum etiology.
Thirty-two patients with cACC and 9 with pACC were identified on an Institutional Review Board-approved retrospective review. Of the 41 cases, 40 had prenatal US, and 21 had prenatal MRI; 17 had follow-up neonatal US, and 14 had follow-up neonatal MRI. Variables evaluated retrospectively were the presence of a CSP or a pseudocavum, ventricle size and shape, and FH shape (comma, trident, parallel, golf club, enlarged, or fused). Displacement between the inferior edge of the FH and the midline or cavum/pseudocavum was measured.
Fetal FHs had an abnormal shape in 77% ≤20 weeks' gestation, 86% ≤24 weeks, and 90% >24 weeks. Frontal horns were laterally displaced greater than 2 mm in 85% ≤20 weeks, 91% ≤24 weeks, and 95% >24 weeks. The CSP was absent in 100% of cACC cases and 78% of pACC cases, and a pseudocavum was present in 88% of cACC cases and 78% of pACC cases across gestation. Magnetic resonance imaging confirmed US pseudocavums to be focal interhemispheric fluid or an elevated/dilated third ventricle.
Frontal horns assist in assessing ACC ≤24 weeks and throughout gestation. Pseudocavums, often simulating CSPs, are common in ACC. Frontal horn lateral displacement and abnormal morphology, recognized by MRI correlations, are helpful in differentiating a pseudocavum from a true CSP. A normal CSP should not be cleared on screening US unless normally shaped FHs are seen directly adjacent to it.
我们假设：（1）胎儿额角（FH）形态及其与透明隔腔（CSP）的接近程度，能够比已知的间接超声（US）检查结果更早地协助怀疑胼胝体完全发育不全（cACC）和胼胝体部分发育不全（pACC）；（2）额角有助于区分真正的透明隔腔与假腔；（3）磁共振成像（MRI）有助于了解额角形态和假腔病因。
通过机构审查委员会批准的回顾性研究，确定了32例cACC患者和9例pACC患者。在这41例病例中，40例进行了产前超声检查，21例进行了产前MRI检查；17例进行了新生儿随访超声检查，14例进行了新生儿随访MRI检查。回顾性评估的变量包括是否存在透明隔腔或假腔、脑室大小和形状以及额角形状（逗号形、三叉戟形、平行形、高尔夫球杆形、增大或融合）。测量额角下缘与中线或腔隙/假腔之间的位移。
妊娠≤20周时，77%的胎儿额角形状异常；≤24周时，86%异常；>24周时，90%异常。妊娠≤20周时，85%的额角向外侧移位大于2mm；≤24周时，91%；>24周时，95%。100%的cACC病例和78%的pACC病例不存在透明隔腔，整个妊娠期88%的cACC病例和78%的pACC病例存在假腔。磁共振成像证实超声检查发现的假腔为局灶性半球间液体积聚或第三脑室升高/扩张。
额角有助于在妊娠≤24周及整个妊娠期评估胼胝体发育不全。假腔在胼胝体发育不全中很常见，常模拟透明隔腔。通过MRI相关性识别的额角外侧移位和异常形态有助于区分假腔与真正的透明隔腔。除非在筛查超声中直接看到形状正常的额角紧邻透明隔腔，否则不应排除正常透明隔腔的存在。
