Caspi Yaron, de Zwarte Sonja M C, Iemenschot Iris J, Lumbreras Raquel, de Heus Roel, Bekker Mireille N, Hulshoff Pol Hilleke
Department of Psychiatry, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht, Netherlands.
Department of Obstetrics and Gynaecology, St. Antonius Hospital, Utrecht, Netherlands.
Front Neuroimaging. 2022 Nov 4;1:996702. doi: 10.3389/fnimg.2022.996702. eCollection 2022.
Three-dimensional fetal ultrasound is commonly used to study the volumetric development of brain structures. To date, only a limited number of automatic procedures for delineating the intracranial volume exist. Hence, intracranial volume measurements from three-dimensional ultrasound images are predominantly performed manually. Here, we present and validate an automated tool to extract the intracranial volume from three-dimensional fetal ultrasound scans. The procedure is based on the registration of a brain model to a subject brain. The intracranial volume of the subject is measured by applying the inverse of the final transformation to an intracranial mask of the brain model. The automatic measurements showed a high correlation with manual delineation of the same subjects at two gestational ages, namely, around 20 and 30 weeks (linear fitting R(20 weeks) = 0.88, R(30 weeks) = 0.77; Intraclass Correlation Coefficients: 20 weeks=0.94, 30 weeks = 0.84). Overall, the automatic intracranial volumes were larger than the manually delineated ones (84 ± 16 vs. 76 ± 15 cm; and 274 ± 35 vs. 237 ± 28 cm), probably due to differences in cerebellum delineation. Notably, the automated measurements reproduced both the non-linear pattern of fetal brain growth and the increased inter-subject variability for older fetuses. By contrast, there was some disagreement between the manual and automatic delineation concerning the size of sexual dimorphism differences. The method presented here provides a relatively efficient way to delineate volumes of fetal brain structures like the intracranial volume automatically. It can be used as a research tool to investigate these structures in large cohorts, which will ultimately aid in understanding fetal structural human brain development.
三维胎儿超声常用于研究脑结构的容积发育。迄今为止，用于勾勒颅内容积的自动程序数量有限。因此，三维超声图像的颅内容积测量主要是手动进行的。在此，我们展示并验证了一种从三维胎儿超声扫描中提取颅内容积的自动化工具。该程序基于将脑模型配准到受检者大脑。通过将最终变换的逆变换应用于脑模型的颅内掩码来测量受检者的颅内容积。自动测量结果显示，在两个孕周（即约20周和30周）时，与同一受检者的手动勾勒结果具有高度相关性（线性拟合：R(20周)=0.88，R(30周)=0.77；组内相关系数：20周=0.94，30周=0.84）。总体而言，自动测量的颅内容积大于手动勾勒的结果（分别为84±16 vs. 76±15 cm³；以及274±35 vs. 237±28 cm³），这可能是由于小脑勾勒方式的差异。值得注意的是，自动测量结果再现了胎儿脑生长的非线性模式以及较大胎儿个体间变异性的增加。相比之下，在性二态性差异大小的手动和自动勾勒之间存在一些分歧。本文介绍的方法提供了一种相对有效的方式来自动勾勒胎儿脑结构的容积，如颅内容积。它可作为一种研究工具，用于在大型队列中研究这些结构，这最终将有助于理解胎儿人类脑结构的发育。
