Alteration of human fetal subplate layer and intermediate zone during normal development on MR and diffusion tensor...

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Histology

Background:

• The subplate and intermediate zone are crucial precursors for neonatal white matter development.
• Understanding their microstructural changes is key to assessing fetal brain development.

Purpose of the Study:

• To evaluate T1 and T2 signal intensity and fractional anisotropy (FA) of fetal subplate and intermediate zones using postmortem MRI.
• To correlate these MR findings with histological examination.
• To assess T2 signal intensity of these zones on antenatal MRI.

Main Methods:

• Postmortem MRI (1.5T) including Diffusion Tensor Imaging (DTI) on 14 fetal brains (18-25 weeks gestation).
• Histologic examination of the same brains.
• Antenatal MRI evaluation of 17 normal fetal brains (20-26 weeks gestation).
• Correlation of MR signal intensity and FA with gestational age and histology.

Main Results:

• Postmortem MRI showed distinct T1 and T2 signal intensities for subplate and intermediate zones, with significant correlations to gestational age.
• Fractional anisotropy (FA) of both zones showed significant correlations with age, reflecting microstructural changes.
• Histology confirmed decreasing extracellular matrix and increasing cellularity in the subplate, and decreasing cellularity with thicker fibers in the intermediate zone.
• Antenatal T2-weighted MRI findings mirrored postmortem results.

Conclusions:

• Signal intensity and FA changes in the fetal subplate and intermediate zones during the second trimester are indicative of underlying microstructural development.
• MRI, particularly DTI, can non-invasively assess these developmental changes in utero.