Post-mortem MRI assessment of fetal corpus callosum growth patterns between 14 and 22 weeks of gestation

Introduction: The corpus callosum (CC) is the largest commissural tract in the human brain, playing a crucial role in interhemispheric communication and neurodevelopment. Although ultrasonography and MRI have been used to assess callosal morphology, most available data are from later gestational ages, with limited normative information for fetuses below 20 weeks. This study aims to fill this gap by evaluating the biometry of the corpus callosum using high-resolution post-mortem fetal brain MRI between 14 and 22 gestational weeks. Materials and Methods: This observational cross-sectional study analyzed post-mortem MRI scans of 77 neurotypical fetal brains aged 14-22 gestational weeks. Imaging was performed on a 3T MRI scanner using a dedicated fetal protocol. T2-weighted STIR sequences provided optimal contrast for delineating the corpus callosum. The anteroposterior (AP) length and body thickness were measured on mid-sagittal images. Data were analyzed using SPSS with descriptive statistics, Pearson’s correlation, linear regression, and ANOVA at a significance level of p < 0.05. Results: The mean AP length of the corpus callosum was 1.78 ± 0.69 cm, and the mean body thickness was 0.171 ± 0.031 cm. AP length showed a strong positive correlation with gestational age (r = 0.952, p < 0.001), while body thickness showed a moderate correlation (r = 0.613, p < 0.001). Conclusion: This study provides early normative post-mortem MRI data of corpus callosum growth between 14 and 22 weeks. The findings establish reference values that may assist in early detection of callosal dysgenesis and related neurodevelopmental abnormalities.