14800-DvRappard

129 Diffusion tensor imaging in metachromatic leukodystrophy 8 in MNI space using the Automated Anatomical Labeling (AAL) atlas. 27 ROIs in MNI space were warped into 3DT1 subject space after linear and non-linear registration. All ROIs were subsequently registered to DTI subject space using nearest neighbor interpolation. The ROIs of motor cortex and cerebral peduncles were used as seed and target for probabilistic tractography using the FSL tools bedpostx and probtrackx2 to obtain the left and right pyramidal tract. 28 Mean diffusion measures within the pyramidal tracts were determined by weighting the underlying FA and diffusivitymaps by the probability of a voxel within the tract. Statistical analysis Statistical analyses were performed for HCT-eligible and non-eligible patients at baseline and control subjects. Groups were compared on demographic variables using ANOVA and chi-square tests, as appropriate. In the TBSS analysis FA, MD, AD and RD were compared between the three groups with nonparametric permutation analysis (randomise), using age and scanner as covariate. We considered a family-wise error corrected p<0.05 significant. General linear model analyses including age and scanner as covariates were performed for a 3-group comparison of diffusion measures at baseline within selected ROIs. In case of main group effects, we performed post-hoc pairwise comparisons between groups, using Dunnett’s T3. The pyramidal tracts primarily regulate motor function. We therefore determined Spearman rank correlations between diffusion measures of all 28 patients at baseline and motor function, determined with MLD-GMF, at latest clinical follow-up. P<0.05 was considered significant. RESULTS Baseline Controls, HCT-eligible and non-eligible patients did not differ on demographic variables. Only for age a main group effect was detected (p 0.017), which was not reflected in post-hoc testing(Table 1).