DTI metrics are often used without assessing the goodness of fit of the estimation model. We investigated local changes in fit residuals induced by pathology. To this end, a template of expected normalized residuals was created with 10 healthy controls, then voxel-wise comparisons were performed against the residuals of subjects affected by dementia. Results show that the residuals of infarcted regions are significantly different as compared to healthy tissue, whereas no differences were observed in hyperintensities. The fit residuals of the DTI model can be used to complement the information of DTI metrics at detecting microstructural changes in brain lesions.