eLife assessment
This paper presents a valuable cross-validation study of mesoscopic measurements of axonal orientations from three different modalities: x-ray tomography, scattered light imaging, and diffusion MRI. The authors show convincing similarities and differences in fibre orientations from all three methods over partial ex vivo brain samples, though as only a single diffusion method is investigated, there is inadequate evidence to support conclusions about diffusion MRI reconstruction methods in general. As a first example of work comparing these three modalities, it is of interest to researchers who want to apply x-ray tomography or scattered light imaging to image the white matter ex vivo or use these methods for future validation of diffusion MRI methods.