Magnetic resonance imaging (MRI) allows to obtain various types of brain images. A particular MRI method is diffusion tensor imaging (DTI), which can visualize nerve fiber pathways. The method is indirect, involving complicated mathematical models to infer this kind of information from the raw data. Therefore, it has to be investigated whether the results match the actual fiber architecture in practice. Parts of this PhD thesis are concerned with this problem: DTI results were compared to microscopical scans of brain tissue, where nerve fibers had been stained. Doing so, it was shown that DTI indeed works as theoretically supposed to.