Access Type

Open Access Dissertation

Date of Award

January 2014

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biomedical Engineering

First Advisor

Ewart M. Haacke

Abstract

Iron plays a key role in a number of brain cellular processes. However, abnormal brain iron regulation correlates with a number of neurodegenerative diseases such as Parkinson's disease, multiple sclerosis and so forth. To further elucidate the involvement of iron in neurodegenerative disorders, a robust in vivo quantitative non-invasive assessment of normal brain iron deposition over time is essential. A variety of magnetic resonance imaging (MRI) methods have been used to quantify iron both in vivo and in vitro non-invasively. We first created the baseline of phase value and ∆R2^* as a function of age in seven gray matter nuclei. We also studied how the high iron region in the structures change over time, which is a more sensitive way to study the brain iron deposition. Quantitative susceptibility mapping (QSM) is another approch we used to study normal brain iron deposition as a further step since susceptibility is a tissue property that is free from geometry effect and imaging parameters. Except in the thalamus, iron increases over time in the gray matter nuclei. We found iron content decreases as a function of age in thalamus according to the susceptibility measurements. These measured susceptibility values are also compared with the regional iron concentrations taken from the histochemical post mortem study published by Hallgren and Sourander to establish an in vivo quantitative conversion factor between magnetic susceptibility and iron concentration. The correlation between the magnetic susceptibility and iron concentration found in this thesis is 1.03±0.03 ppb per µg iron/g wet tissue.

Idiopathic Parkinson's disease (IPD) remains one of those neurodegenerative diseases where the cause remains unknown. Many clinically diagnosed cases of IPD are associated with cerebrovascular disease and white matter hyperintensities (WMH). In this thesis, we also include a study to investigate the presence of transverse sinus and extracranial venous abnormalities in IPD patients and their relationship with brain WMH. As a result of this preliminary study, we conclude that a major fraction of IPD patients appear to have abnormal venous anatomy and flow on the left side of the brain and neck and that the flow abnormalities appear to correlate with WMH volume.

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