The tensor model has been widely used to infer characteristics of white matter through diffusion MRI. Unfortunately, this model does not provide reliable information about crossing fiber regions. Several models have been proposed that seem to overcome the limitations of the tensor. However, biological interpretations of such models are limited by the lack of histological conformation. Using an animal model of axonal degeneration, we compare histology to data derived from two approaches (CSD and multi-tensor), in an effort to provide validation of metrics that can bring substantial and clinically useful information about crossing fiber regions.