MRI is the method of choice for brain imaging. However, it uses indirect structural information to infer densities of molecules such as myelin, and water diffusion direction as a proxy for fiber direction. Small-angle X-ray scattering tensor tomography (SAXSTT) provides an alternative approach to assess myelin distribution and fiber direction using directly structural information related to the molecular structure of myelin sheath. We applied SAXSTT to mouse brain to validate and compare different MRI methods (MT, DWI). We found a high degree of similarity with MT macromolecule distribution, and also DWI-derived white matter tracts, but with significant region-specific differences.