Jeong-Won Jeong PhD, Presenter: Nothing to Disclose

Ajay Kumar MD, PhD, Abstract Co-Author: Nothing to Disclose

Senthilnathan Sundaram MD, Abstract Co-Author: Nothing to Disclose

Harry T. Chugani MD, Abstract Co-Author: Nothing to Disclose

Diane C Chugani PhD, Abstract Co-Author: Nothing to Disclose

To determine whether curvature analyses of frontal lobe white matter tracts can yield an imaging parameter unique to children with autism spectrum disorder (ASD).

Diffusion tensor MRI with 6 directional gradients and one b0 image was performed in 32 ASD children (mean age: 58.8±22.64 months, 29 males) and 14 normal controls (NC, mean age: 67.36±23.81 months, 11 males). Conventional streamline tractography and SPM DARTEL were used to isolate whole brain fiber tracts spatially normalized to MNI space. Subsequently, atalas-based ROI appraoch was used to isolate bilateral uncinate fasciculus (UF), arcuate fasciculus (AF), and genu of corpus callosum (gCC). For each fiber tract, tract-based morphometry (TBM) analysis was applied to localize the regions showing significant change in the curvature. The longest fiber penetrating the highest fiber density region of a given tract in the NC group was selected as a ‘prototype’ for that particular tract and was used to define the common arc-length coordinates for that tract. This prototyp was used to find the corresponding coordinates of individual fibers of the respective tract in each subject. Using Frenet’s equation, the curvature of each fiber tract at each coordinate was calculated in each subject and their group difference was examined by two sample t-test corrected for multiple comparisons .

Significantly higher curvature values (p<0.05) were found for all the measured tracts in the ASD group compared to controls, a result of sharper bends at the fronto-temporal junction for UF (0.18±0.05 vs. 0.16±0.04), at the parieto-temporal junction for AF (0.18+0.03 vs. 0.14±0.03), and at the midline of the gCC (0.17±0.02 vs. 0.13±0.01, respectively). These regions are indicated by black arrows in the attached figure.

Bilateral AF and UF, and gCC have higher curvature and sharper bending in children with ASD, perhaps resulting from differences in brain growth.

Our finding suggests that the fiber tract curvature can be used as robust feature to quantify aberrant white matter geometry (developmental trajectory) in children with ASD.

Jeong, J, Kumar, A, Sundaram, S, Chugani, H, Chugani, D, Curvature of Frontal Lobe White Matter Pathways in Children with Autism Spectrum Disorder.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011144.html