Diffusion-tensor MR imaging in children with developmental delay: preliminary findings.

PURPOSE To determine whether diffusion-tensor magnetic resonance (MR) imaging can depict abnormalities in patients with a diagnosis of developmental delay but structurally normal brain MR imaging results. MATERIALS AND METHODS Twenty pediatric patients who received a diagnosis of developmental delay underwent brain MR examinations, including diffusion-tensor MR imaging. The MR findings in these patients were compared with those in 10 age-matched neurodevelopmentally healthy children. Diffusion constant (Dav) and anisotropy were measured bilaterally in regions of interest in the centrum semiovale, corona radiata, internal capsule, corpus callosum, and subcortical white matter of the frontal and parieto-occipital lobes. By using a one-tailed Student t test in the positive direction for Dav and in the negative direction for anisotropy and P <.05 to indicate a significant difference, the Dav and anisotropy values for children with developmental delay were compared with those for children who were neurodevelopmentally healthy. RESULTS The children with developmental delay had significant increases in Dav in all measured structures (P, <.001 to <.03). Significant decreases in anisotropy were detected in all white matter fiber tracts studied (P, <.001 to <.03) except the posterior limb of the internal capsule. CONCLUSION In the children with developmental delay, diffusion-tensor MR imaging depicted decreases in anisotropy and increases in Dav in the white matter fiber tracts, which appeared to be normal at conventional MR imaging.