Access Type

Open Access Thesis

Date of Award

January 2016

Degree Type

Thesis

Degree Name

M.S.

Department

Biomedical Engineering

First Advisor

Ewart M. Haacke

Abstract

As the most abundant transition metal in the brain, iron is known to play a key role in a variety of functional and cellular processes. Recent in vivo and post-mortem studies have shown that the levels of iron deposition in the brain, particularly in deep gray matter nuclei, vary as a function of age. On the other hand, elevated iron has also been associated with some neurodegenerative diseases such as Multiple Sclerosis (MS) and Parkinson’s disease (PD) among others.

Magnetic Resonance Imaging (MRI) is a widely used non-invasive and non-ionizing imaging modality which is sensitive to magnetic properties of materials through their magnetic susceptibilities. This makes it particularly useful in imaging as iron (which is paramagnetic) and calcium (which is diamagnetic). Recent developments in magnetic susceptibility mapping have made it possible to track iron changes in the brain. In this thesis, Quantitative Susceptibility Mapping (QSM) is used to establish a baseline of iron content in the basal ganglia, midbrain, and cerebellar major nuclei as a function of age in healthy controls using both global (whole 3D structural region) and regional (high iron content region) analyses.

In agreement with previous studies, we found that in the global analysis a positive linear susceptibility-age correlation was observed in the putamen, caudate nucleus, and red nucleus while the susceptibility distributions across the lifespan were quite scattered in the globus pallidus, substantia nigra, thalamus, pulvinar thalamus and dentate nucleus. All structures, with the exception of the thalamus, showed increasing susceptibility trend as a function of age in the whole-region analysis. However, in the high iron content region, strong and considerably less scattered correlations were shown between age and magnetic susceptibility in most of the structures, except for the thalamus. These sensitive and robust regional susceptibility-age correlations have the potential to be utilized as a new baseline to investigate abnormal iron content in neurological diseases.

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