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AJNR - American Journal of Neuroradiology

Published ahead of print on May 8, 2008
doi: 10.3174/ajnr.A1007

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American Journal of Neuroradiology 29:1134-1139, June-July 2008
© 2008 American Society of Neuroradiology

BRAIN

Tract-Based Spatial Statistics of Diffusion Tensor Imaging in Adults with Dyslexia

T. Richards^a, J. Stevenson^a, J. Crouch^d, L.C. Johnson^b, K. Maravilla^a, P. Stock^c, R. Abbott^c and V. Berninger^c

^a Department of Radiology, University of Washington, Seattle, Wash
^b Psychosocial and Community Health, School of Nursing, University of Washington, Seattle, Wash
^c Educational Psychology, University of Washington, Seattle, Wash
^d School of Medicine, Saint Louis University, St Louis, Mo

Please address correspondence to Todd Richards, Department of Radiology, Box 357115, Room AA010, Health Sciences Building, 1959 NE Pacific, Seattle, WA 98195; e-mail: toddr{at}u.washington.edu

BACKGROUND AND PURPOSE: Diffusion tensor imaging is a tool that can be used to study white matter microstructure in dyslexia. We tested the hypothesis that dyslexics have a white matter structural change (as measured by directional diffusion of water, which can be affected by disruption in white matter tracts) between brain regions that previous functional connectivity studies showed were associated with phonologic processing.

MATERIALS AND METHODS: Diffusion tensor imaging (DTI) scans were acquired from 7 healthy adult normal readers and from 14 adults with dyslexia on a 1.5T scanner. Voxelwise statistical analysis of the fractional anisotropy data were carried out by using Tract-Based Spatial Statistics to compare dyslexic subjects versus control subjects in white matter tracts.

RESULTS: Significant group difference map clusters (comparing adults with and without dyslexia) occurred in specific bilateral white matter tracts within the frontal lobe, temporal lobe, occipital lobe, and parietal lobe.

CONCLUSION: The DTI fractional anisotropy results in the bilateral white matter showing higher fractional anisotropy in adult control subjects compared with adults with dyslexia (relating to white matter fiber tract integrity) are consistent with our previous functional connectivity results from seed points in the bilateral inferior frontal gyrus.