Date of Graduation

8-2016

Document Type

Thesis (MS)

Program Affiliation

Medical Physics

Degree Name

Masters of Science (MS)

Advisor/Committee Chair

James Bankson, PhD

Committee Member

Jason Stafford, PhD

Committee Member

Donna Reeve, MS

Committee Member

David Followill, PhD

Committee Member

Arvind Rao, PhD

Abstract

AN AUTOMATED SYRINGE PUMP SYSTEM FOR IMPROVING THE REPRODUCIBILITY OF DYNAMIC HYPERPOLARIZED MRI PHANTOMS

Harlee Grace Harrison, B.S.

Advisory Professor: James Bankson, Ph.D.

Magnetic Resonance Imaging (MRI) is a powerful tool in the diagnosis of cancer due to its ability to provide good soft tissue contrast and image resolution without the use of ionizing radiation. The use of hyperpolarized pyruvate as a contrast agent for tumor metabolism during MR scans has the potential to provide information about tumor metabolism in vivo that is not available from traditional imaging measurements or any other method. Hyperpolarization is achieved through dynamic nuclear polarization. This is a process in which a sample is quickly frozen to near absolute zero (~1.4K), and placed in a strong magnetic field. In these conditions, magnetization in unpaired electrons, in this case from a Trityl radical, can convey their polarization to a nearby 13C nucleus through microwave irradiation. Pyruvate, which plays a central role in metabolism, is involved in aerobic glycolysis, a primary energy pathway for cancer cells. In this process, known as the Warburg effect, the up-regulation of lactate dehydrogenase leads to the increased chemical conversion of pyruvate to lactate. Due to the conservation of hyperpolarized 13C-enriched pyruvate’s nuclear spin state through chemical conversion, the signal from pyruvate and metabolites such as lactate can be observed. Although the signal is largely increased, this improvement is short lived. The hyperpolarization of pyruvate only lasts for a few minutes and this time is shortened when in the scanner due to excitation losses. The use of hyperpolarized pyruvate in the clinic is promising, but requires development of robust methods to ensure the reproducibility of results. The purpose of this work is to design an automated dynamic phantom system that will allow for the characterization and optimization of quantitative imaging and analysis strategies. We have created a hydraulic pump system that reduces the variance in the reproducibility of hyperpolarized 13C reaction rates and signal evolution. Eliminating error in the methods of injection, will allow focus on the reduction of error due to imaging strategies.

Keywords

MRI, Phantom, Hyperpolarized, Pyruvate, Reproducibility, Syringe Pump, Hydraulic

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