Implications of Heterogeneous Variance of Tensor-Derived Quantities for Group Comparisons

Diffusion tensor imaging (DTI) is a quantitative MRI method that is widely used to study the microstructural properties of white matter in the brain. This sensitivity to microstructure and tissue organization makes DTI an important tool for studying the normal, diseased, and developing brain. DTI is applied to studies in which scans of subjects from a patient group and a control group are compared. In performing group analysis on each voxel (as in voxel based morphometry (VBM)) or region of interest (ROI) analysis, the mean values of tensor-derived quantities, such as trace and fractional anisotrop