Cognitve Deficits in Huntington's Disease Associated to White Matter.xlsx

Fractional anisotropy (FA) and mean diffusivity (MD) were assessed in 22 HD patients and 20 healthy controls to investigate the relationship between cognitive performance, measured by the Montreal Cognitive Assessment (MoCA), and white matter (WM) microstructural changes in Huntington’s disease (HD).<br>All images were acquired using a 3T MRI scanner (Philips Medical Systems, Eindhoven, The Netherlands). The high-resolution anatomical acquisition consisted of a T1-3D Fast FieldEcho sequence with the following parameters: TR/TE: 8/3.7 ms; FOV: 256 × 256 mm2 ; Flip angle = 8˚; acquisition and reconstruction matrix: 256 × 256; and isometric resolution: 1 × 1 × 1 mm3. All imaging data were acquired with informed consent at the National Institute of Neurology and Neurosurgery in Mexico City.<br>The mean FA images from all participants were aligned to a standard template and then skeletonized to create a ‘white matter skeleton’, representing the centers of all major white matter tracts common to the group. This skeleton serves as a spatial framework onto which each individual’s FA data are projected, minimizing partial volume effects and misalignment between subjects.<br>DTI data were converted from DICOM to NIfTI format using MRIcron’s dcm2niigui, followed by eddy current correction and generation of binary brain masks. Diffusion tensors were reconstructed to obtain FA maps. Tract-Based Spatial Statistics (TBSS) analysis was conducted using the FMRIB Software Library (FSL). Preprocessed FA images were aligned to a standard FA template through nonlinear registration (tbss_2_reg -T), skeletonized to extract the core white matter tracts (tbss_3_postreg -S), and thresholded at FA &gt; 0.2 (tbss_4_prestats).<br>Group comparisons were modeled using design matrices created with FSL’s GLM Setup, and statistical inference was performed using the randomise tool with 10,000 permutations and threshold-free cluster enhancement (TFCE). MD maps were computed using dtifit, linearly registered to MNI152 space via flirt, and projected onto the FA skeleton using tbss_skeleton and analyzed with tbss_non_FA.<br><br>