Date of Award
Dr. Joseph Bradshaw
Dr. Joe Jeffers
Dr. Johnny Wink
Magnetic resonance imaging (MRI) is a medically important test that provides a painless, noninvasive way to visualize images of the body by using a strong magnetic field. The machine quickly changes the direction of the magnetic field in certain increments and measures the time it takes for protons to change their direction, lining up with the magnetic field again. The time taken for the protons to realign is called the overall relaxivity rate (R1). Abnormalities, especially tumors, are expressed in MRI images because their relaxivity rates are quite different from the relaxivity rates of normal tissues.
To help enhance MRI images, several contrast agents have been developed in the past that can be injected into the patient's bloodstream. The contrast agents studied and synthesized in this research contain a metal called gadolinium. Contrast agents containing gadolinium can be excreted in the urine by glomerular filtration, which is a key characteristic of most contrast agents in general. In the last few decades, the use of contrast agents has drastically increased due to their enhancement and increased specificity. The most common contrast agents currently used include Magnevist, ProHance, and Omniscan.
For the contrast agent to be useful and effective, it must have several key characteristics. First, it must have an adequate amount of tissue specificity. When injected into the patient, it should go to one area of the body in a higher concentration than anywhere else. The agent must also stay there long enough to allow for image enhancement. Second, the contrast agent must have a long shelf life. If the material isn't stable, not only is it unsafe to use, it won't be available for long-term use. A contrast agent should have a shelf life of years, not months or days. Third, as mentioned before, the body must be able to completely remove the contrast agent from the targeted area or organ. While most contrast agents are excreted in the urine, it must also have low toxicity as to prevent harming the patient. Lastly, to minimize dosage, the contrast agent must be able to alter the image intensity at a low concentration. This helps keep the dosage at a minimum while still producing enhance images (Contrast Media 454).
In this research several different synthesis reactions were completed and tested for accuracy, using NMR and thin-layer chromatography (TLC). The results ensured that the desired product was produced before proceeding with the next reaction. This thesis describes the synthesis, purification, characterization, and testing of a novel contrast agent, comparing it to current contrast agents being used today. The final product was tested using T1 relaxation rates to compare the newly developed agent, which was synthesized using a piperazine-methoxyphenyl group, to those contrast agents in use today.
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Clement, Callie, "Synthesis and Relaxivity of a Target-Specific MRI Contrast Agent" (2018). Honors Theses. 646.