Free Water Corrected Diffusion Magnetic Resonance Imaging Reveals Microstructural Alterations in Corpus Callosum Subregions of Preschool Children With Autism.

Researchers used advanced brain scans to study the corpus callosum (the bridge connecting brain hemispheres) in 61 preschool children with autism and 62 children without autism. They found specific differences in brain tissue structure, particularly in areas connecting to the temporal and frontal brain regions. These brain differences were linked to autism symptom severity, suggesting they may help explain some autism characteristics. The study highlights potential for earlier diagnosis and monitoring treatment progress.

This neuroimaging study used advanced diffusion MRI techniques to examine white matter microstructure in the corpus callosum of 61 preschool children with autism (aged 6.03±1.08 years) compared to 62 typically developing controls (aged 6.49±1.45 years). The free water corrected diffusion MRI method was employed to reduce measurement artifacts and provide more precise tissue characterization. Results revealed specific alterations in corpus callosum subregions: reduced tissue integrity in temporal lobe connections (CC6) and decreased free water in frontal connections (CC1). Importantly, frontoparietal connectivity measures correlated with autism symptom severity scores, suggesting these brain differences may relate to clinical presentation.

The findings implicate disrupted myelination in temporal pathways and abnormal axonal development in frontal brain regions.

Findings suggest potential for neuroimaging biomarkers in early autism diagnosis and intervention monitoring. The correlation between brain connectivity and symptom severity may inform personalized treatment approaches and outcome prediction in preschool children with autism.

Single-center study with moderate sample size. Cross-sectional design prevents determination of causality or developmental trajectories. The study type is not clearly specified, and long-term clinical outcomes were not assessed.

Autism spectrum disorder (ASD) is associated with white matter microstructural abnormalities, particularly in the corpus callosum (CC). This study employed free water corrected diffusion magnetic resonance imaging (fwc-dMRI) to investigate CC subregion-specific microstructural alterations in preschool children with ASD, which mitigates partial volume effects from extracellular free water. Sixty-one ASD children (6.03 ± 1.08 years) and 62 typically developing (TD) controls (6.49 ± 1.45 years) were enrolled in this study. In the ASD group, the symptom severity was assessed by the Autism Behavior Checklist (ABC).

Fwc-dMRI technique, a bi-tensor tractography method, was used to investigate the white matter microstructure, which models free water and brain tissues through isotropic and anisotropic tensors to eliminate the partial volume effects caused by extracellular free water. The CC was segmented into seven subregions automatically according to its alignment to the cortex by a robust machine learning approach based on an anatomically curated white matter atlas. Fwc-dMRI-derived metrics were extracted for each CC subregion. Then we compared diffusion metrics between the two groups, and the correlation between the fractional anisotropy tissue (FA) and the scores of the ABC scale was analyzed in ASD.

Significant group differences were localized to CC6 (temporal lobe projections), showing reduced FA(t = -3.251, p < 0.01) and elevated radial diffusivity tissue (t = 3.632, p < 0.01), and CC1 (orbital lobe projections), exhibiting decreased free water (t = -3.068, p < 0.05). FAin CC2-5 negatively correlated with ABC scores (r = -0.36 to -0.52, p < 0.01), linking frontoparietal connectivity to the symptom severity of ASD. Fwc-dMRI identified distinct microstructural disruptions in CC subregions, implicating dysmyelination in temporal pathways (CC6) and abnormal axonal development in frontal projections (CC1). These findings highlight fwc-dMRI's potential for early ASD diagnosis and intervention monitoring.