The effect of corpus callosum abnormalities on myelin development in the fetal brain using the fast macromolecular proton fraction mapping

INTRODUCTION: There is evidence, indicate early compensatory axonal remodeling connections in the prenatal period, providing a favorable neurological outcome in isolated anomalies of the corpus callosum (CC). Mapping of the macromolecular proton fraction (MPF) is proven method of quantitative determination of myelin, which has been adapted for prenatal studies. OBJECTIVE: To investigate the relationship between CC anomalies and prenatal myelination of the brain using the fast macromolecular proton fraction (MPF) mapping. MATERIALS AND METHODS: Fetal MR imaging were performed on a 1.5 scanner (Achieva, Philips) using a 16-channel body coil. Of 66 fetal brains MRI, 12 studies were selected with MT abnormalities (22.8±2.8, 19–28.5 WG) and 21 without brain pathology (23.1±2.3, 20–29.5 WG). The images were analyzed according to structural MRI data (T2-Ssh and T1-GE, EPI, DWI, MYUR, T2-BFE-DYN) by two experienced radiologists. Fast-3D-MPF scan protocol with the MPF maps reconstruction was carried out according to a specialized protocol (open-source software: https://www.macroatomicmri.org /). Quantitative data were obtained by choosing the region of interest (ROI) in numerous brain structures bilateral (bridge, medulla oblongata, thalamus, cerebellum, and cerebral hemispheres). Statistics: distinctions between the groups and structures were assessed using repeated-measures analysis of covariance (ANCOVA), Pearson correlation analysis. RESULTS: MPF was significantly increased in the CC anomalies group as compared to controls in the medulla (3.26±0.63% vs. 2.75±0.59%, р=0.001) and cerebellum (2.02±0.55% vs. 1.76±0.34%, р=0.006). In hemispheres significant correlation with GA was observed in CC anomalies group (r=0.81, р=0.002), but was absent in controls (r=0.32, р=0.16). CONCLUSION: Primary observed MPF increase in the medulla and cerebellum as well as the dependence of the large hemispheres myelination on gestational age indicates that fetal cerebral matter undergoes early compensatory axonal remodeling in the cases of the interhemispheric connections’ reduction.