Post-mortem Assessment of Iron in Multiple Sclerosis Brain using Magnetic Resonance Imaging

Iron plays an important role in the metabolism of the human brain. There is evidence that the iron metabolism is disturbed, and abnormal iron accumulation can occur in neurological diseases such as multiple sclerosis (MS). Magnetic resonance imaging (MRI) is a suitable tool to assess iron inside biological tissue. State of the art MRI techniques to quantify iron are restricted to gray matter, due to the confounding influence of diamagnetic contributions caused by myelin. Thus, there is need for a suitable technique to quantify iron independent of myelin. In this thesis, a novel MRI technique for iron mapping, independent of diamagnetic contributions, is presented. This technique is based on the temperature dependency of the paramagnetic susceptibility, described by Curie's law. Temperature dependent MRI was applied on post-mortem MS brain tissue. The captured iron maps based on the temperature coefficient of R2* were in agreement with histopathological results and literature. In post-mortem MRI, temperature, tissue fixation and autolysis processes are affecting MRI image contrast and quantitative relaxation parameters. A detailed examination of the post-mortem effects in MRI was part of the thesis. This work showed for the first time quantitative iron maps of white and gray matter structures. In conclusion, this technique showed the suitability of temperature dependent MRI to reveal novel insights into the iron distribution in MS brain tissue.