Aberrant diffusion and geometric properties in the left arcuate fasciculus of developmentally delayed children: a diffusion tensor imaging study.

BACKGROUND AND PURPOSE One of the neurologic substrates of poor language in children with DD is the abnormal development of perisylvian language networks. We sought to determine whether this manifests as aberrant regional changes in diffusivity or geometry of the left AF. MATERIALS AND METHODS We performed DTI studies in 16 young (age, 55.4 ± 18.95 months) patients with DD and 11 age- and sex-matched TD children (age, 60.09 ± 21.27 months). All children were right-handed. To detect the malformation of left AF structure in native or standard space, we proposed new methodology consisting of 2 complementary approaches, principal fiber orientation quantification in color-coded anisotropic maps and tract-based morphometry analysis. RESULTS Patients with DD did not show the typical pattern of age-related maturity of the AP and ML pathways passing through the left AF (R(2) of the AP pathway: DD versus TD = 0.002 versus 0.4542; R(2) of the ML pathway: DD versus TD = 0.002 versus 0.4154). In addition, the patients with DD showed significantly reduced FA in the temporal portion of the AF (mean FA of DD versus TD = 0.37 ± 0.11 versus 0.48 ± 0.06, P < .001), and the AF showed higher curvatures in the parietotemporal junction, resulting in sharper bends to the Wernicke area (mean curvature of DD versus TD = 0.12 ± 0.03 versus 0.06 ± 0.02, P < .001). CONCLUSIONS The proposed methods successfully revealed regional abnormalities in the axonal integrity of the left AF in the patients with DD. These abnormalities support the notion that the perisylvian language network is malformed in children with DD.