Longitudinal magnetic resonance imaging reveals differences in cortical expansion in fetuses with congenital heart defects.

For children with congenital heart disease (CHD), differences in brain structure are already present at birth. Cortical surface area and gyrification increase dramatically over the third trimester, and cortical expansion has been hypothesized to drive brain folding. This study sought to quantify differences in cortical expansion in fetuses with CHD and typically developing controls. Fetal magnetic resonance imaging was conducted at early (26-31 weeks) and late (34-39 weeks) gestational time points, and cortical surfaces were reconstructed using a high resolution, motion-corrected pipeline. For fetuses with reconstructions at both time points (36 CHD, 24 control), anatomically-constrained multimodal surface matching (aMSM) was used to generate individualized maps of cortical surface expansion. Global analysis revealed significant reductions in total cortical expansion and gyrification index among CHD fetuses. Furthermore, expansion maps revealed high expansion in the lateral temporal lobes of control fetuses that was reduced in fetuses with CHD, consistent with previous reports of atypical folding in this region. This study is the first to reveal spatiotemporal patterns of cortical expansion in typical and atypical fetal development. This detailed understanding of cortical growth trajectory may improve understanding of functional deficits associated with specific cortical areas and inform clinical interventions for patients with CHD.