Several challenges exist in cardiac magnetic resonance imaging (MRI) as a result of the constant motion of the heart. In order to create a cardiac image with both high spatial and temporal resolution, MR data must be obtained from multiple cardiac cycles; therefore, a means of synchronization for segmented acquisition is needed. The electrocardiogram (ECG) is typically used for this gating task, but there are multiple sources of interference which corrupt the ECG in the MR environment, including radiofrequency pulses, gradient switching, and the magnetohydrodynamic (MHD) effect. This work involved investigation of different aspects of both ECG-gating and self-gating. For ECG-gating, we specifically focused on examination of the MHD voltages, since there are already well-established methods for removing artifacts from both radiofrequency pulses as well as gradient switching. To better understand MHD voltages in order to remove them from the ECG as well as to extract them for separate analysis, we developed several finite element models of MHD voltages in the MR environment and compared the results with experimental data. We also investigated improved cardiac synchronization position detection techniques for self-gated cardiac MRI. Self-gating is not currently used in clinical practice, but with improved post-processing algorithms, it shows promise as a feasible alternative gating method. In addition to improvements in gating for cardiac MRI, we also investigated a new method for detection of atherosclerotic plaques in the lower extremities. This study is based upon the principle that plaques in the arteries obstruct blood flow, resulting in altered flow and, depending on the degree of occlusion, turbulence. The objective of this study was to create a finite element model of MHD voltages in the human thigh for both healthy and diseased arteries, in order to determine if measuring MHD voltages may be a feasible method for detection of athersclerotic plaques in the lower extremities since MHD voltages are directly related to blood flow.

Last modified

• 09/20/2018

Creator

• Grace Mary Nijm

DOI

• https://doi.org/10.21985/N2673X

Subject

• Electrical and Computer Engineering

Keyword

• Self-gating
• Cardiac MRI
• Magnetohydrodynamic effect
• ECG-gating

Date created

• 2008-12-05

Resource type

• Dissertation

Rights statement

• In Copyright