Voxel-Based DTI of Longitudinal Changes Post Pediatric TBI Compared with Age-Matched Developing Controls

Lian Xue¹, Khader M. Hasan, Larry A. Kramer, Linda Ewing-Cobbs

Quantitative diffusion tensor imaging (DTI) has been used to detect serial microstructure changes post moderate and severe TBI. DTI metrics such as fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivities, // and Ɂ revealed subtle differences of grey matter (GM) and white matter (WM) during recovery from TBI. However, there is no systematic whole brain study on the longitudinal evolution of GM and WM diffusion abnormalities during recovery from pediatric TBI patients. In this work, we perform a longitudinal study of 25 pediatric TBI patients who sustained moderate and severe TBI and 21 age-matched pediatric orthopedic comparison subjects. DTI was acquired 3 months after injury for each participant and repeated at 24 months after injury for each participant to examine recovery in the TBI group in relation to normal neurodevelopment changes during childhood and adolescence. Voxel based morphometry (VBM) [3] is adopted for an unbiased longitudinal data analysis and an optimal VBM procedure using the recently available DARTEL technique in SPM8 is developed to minimize misregistration. The VBM results for FA, MD maps of GM and FA, // and Ɂ maps of WM reveal different longitudinal changes in TBI patient cortical and subcortical structures compared with normal neurodevelopment changes, which provide insight into the significant impact of TBI on GM and WM.