Coherent Fourier scatterometry reveals nerve fiber crossings in the brain.

Previous simulation studies by Menzel et al. [Phys. Rev. X 10, 021002 (2020)] have shown that scattering patterns of light transmitted through artificial nerve fiber constellations contain valuable information about the tissue substructure such as the crossing angles of the fibers. Here, we present a method that measures these scattering patterns in monkey and human brain tissue using coherent Fourier scatterometry with normally incident light. By transmitting a non-focused laser beam (wavelength of 633 nm) through unstained histological brain sections, we measure the scattering patterns for small brain regions (0.1-1 mm), and show that they are in accordance with the simulated scattering patterns and reveal the crossing angles for up to three crossing nerve fiber bundles.