MRI evaluation of ADC values and venous variations in fetal cerebral white matter with T2WI signal hyperintensity in late gestation

Background and purpose We observed that some late-term fetal prenatal magnetic resonance imaging (MRI) scans revealed normal brain structures but exhibited diffuse hyperintense signals on T2-weighted imaging (T2WI) in the cerebral white matter (white matter hyperintense signal [WMHS]). Currently, the pathological basis of this phenomenon remains unclear, and few studies have systematically investigated its impact on fetal and postnatal brain development. We aimed to compare the differences in apparent diffusion coefficient (ADC) values across distinct brain regions between fetuses with WMHS and age-matched control fetuses, to explore the potential etiology of WMHS by combining these findings with morphological changes in cerebral veins, and to conduct a comprehensive evaluation combined with clinical follow-up. Method We retrospectively analyzed fetal imaging data from MRI examinations performed at our hospital between January 2014 and May 2024. A total of 87 late-term fetuses (gestational age [GA]: 29–40 weeks) were identified with diffuse hyperintense signals on T2WI in the cerebral parenchyma; age-matched normal fetuses with the same sample size were enrolled as the control group. We compared differences in ADC values across distinct brain regions among fetuses with WMHS and simultaneously analyzed morphological differences in the deep cerebral veins between the two groups, combined with postnatal clinical follow-up, to explore the impact of WMHS on brain development and its clinical significance in late-term fetuses. Results (1) ADC values in the majority of brain regions of fetuses in the WMHS group were higher than those in the control group, with the greatest difference observed in the F2 region. (2) Compared with the control group, fetuses in the WMHS group exhibited significantly increased lumen areas of the vein of Galen (VOG) and straight sinus (SS), with a p -value of < 0.05 considered statistically significant. (3) Successful follow-up was achieved in 45 control infants and 36 WMHS cases. All control fetuses showed normal neurodevelopmental outcomes, while 33 infants in the WMHS group had normal and 3 had adverse outcomes, including cerebral palsy, developmental delay, and autism. Conclusion In late-term fetuses with WMHS, elevated ADC values in specific brain regions and concurrent deep cerebral venous dilation indicate underlying intracranial abnormalities. In addition, our follow-up results indicate that these combined changes may be associated with adverse neurodevelopmental outcomes in some infants.