Characterizing microstructural development in the fetal brain using diffusion MRI from 23 to 36 weeks of gestation

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Biomedical Engineering

Background:

• Fetal brain development involves complex microstructural changes.
• Diffusion tensor imaging (DTI) is a powerful tool for assessing white matter microstructure.
• Understanding normal fetal brain development is crucial for identifying potential abnormalities.

Purpose of the Study:

• To evaluate microstructural changes in healthy fetal brains during late second and third trimesters using motion-corrected DTI.
• To characterize the developmental trajectories of fractional anisotropy (FA) and mean diffusivity (MD) in various fetal brain regions.
• To identify potential hemispheric asymmetries in fetal brain development.

Main Methods:

• Utilized motion-corrected diffusion tensor imaging (DTI) from 44 fetuses (23-36 weeks gestational age).
• Reconstructed DTI using a motion-tracked slice-to-volume registration framework.
• Segmented 14 regions of interest (ROIs) using a fetal DTI atlas and analyzed FA and MD changes with mixed-effects models.

Main Results:

• Significant gestational age-related changes in FA and MD were observed in most ROIs.
• Exceptions included thalamus FA and corpus callosum MD, which showed no significant changes.
• Hemispheric asymmetries were detected in periventricular white matter (pvWM), intermediate zone, subplate FA, and ganglionic eminence and pvWM MD.

Conclusions:

• This study provides valuable insights into normal fetal brain microstructural development patterns.
• Observed changes in FA and MD correlate with cytoarchitectonic development.
• Findings suggest early indications of functional specialization in the developing fetal brain.