Diffusion Tensor Imaging Through Diffusion Tensor Imaging, a type of neuroimaging that builds on MRI technology, doctors can also monitor the health of the brain's white matter. White-matter fibers (called axons) allow communication between brain regions and between the brain and the spinal cord. Damage to this type of tissue may have serious, long-term consequences. In this image, the axons are colored according to orientation. Fibers running between the front and back are blue, those between right and left are red, and those running between the brain's interior and exterior are green.