This study assesses changes in brain anatomy with MRI in the homozygous humanized FUSDelta14 mouse model of amyotrophic lateral sclerosis (ALS). Post-mortem brain T2w-images were acquired at 7T, with 40μm isotropic resolution. After registration, the deformation fields were compared between mutant and wild-type mice. Homozygous FUSDelta14 mice exhibited atrophy in multiple grey and white matter structures. These results are in agreement with observations such as cortical thinning and alterations in white matter microstructure in ALS patients. Homozygous humanized FUSDelta14 mice show an early brain phenotype and are therefore a promising model for the study of ALS pathogenic mechanisms.