Evaluation of fetal brain development in growth restriction subtypes using brain MRI volume measurement

Background This retrospective study aims to explore the value of brain MRI volume measurements in evaluating fetal brain development in fetal growth restriction (FGR) fetuses, by comparing different FGR subtypes with appropriate gestational age (AGA) fetuses. Methods A total of 158 fetal brain MRI with suspected abnormal development, identified through ultrasound screening at this hospital between 2021 and 2025 were analyzed. Ninety-eight cases were FGR fetuses (43 early-onset subtype and 55 late-onset subtype), and 60 were AGA fetuses. Three-dimensional reconstruction and image segmentation were performed on fetus intracranial tissues, brain parenchyma, cerebellum and brainstem. Changes in brain volume at different gestational weeks were analysed to assess the development of fetal brain anatomical structures. Results In both groups, the Pearson correlation coefficients for brain parenchyma, brain stem, and cerebellum volume with head circumference and gestational age were greater than 0.8, indicating a strong correlation. The difference in brain parenchyma, brain stem, and cerebellum volume between early-onset FGR fetuses and AGA fetuses was statistically significant. The difference in brain parenchyma volume between late-onset FGR fetuses and AGA fetuses was statistically significant, while there was no statistically significant difference in brain stem volume between FGR and AGA fetuses at 34 weeks or later, nor in cerebellum volume at 36 weeks or later. Discussion Fetal brain MRI at gestation serve as a valuable supplement to ultrasound screening. This technique helps assess brain development in fetuses with various FGR subtypes, offering further reference for prenatal diagnosticians in evaluating fetal brain development. Further studies are needed to dynamically monitor and assess the prognosis of brain MRI volumes in fetuses with early-onset FGR.