Browsing by Subject "B1 encoding"

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    The Development Of Radiofrequency Imaging Techniques And Compact Nmr Systems To Improve Access To Medical Technology
    (2023-09) Torres, Efrain
    Magnetic Resonance Imaging (MRI) is a seminal tool in modern medicine, but its high cost and complexity drastically limits its availability. MRI systems only serve approximately 10 percent of the population. A need exists to develop affordable, accessible, and clinically valuable technology. This thesis work is focused on developing technology that could make MRI systems more readily available. First, we explored the use of a 0.5 T Halbach magnet, which is a cost-effective and lightweight alternative to traditional magnets. We successfully demonstrate how simple radiofrequency coils and adiabatic pulses can compensate for large magnetic imperfections often found in Halbach magnets. To demonstrate its clinical utility, an R1 relaxometry study was performed on 19F oxygen-probes that were implanted in tissue-engineered grafts. Second, we challenge the conventional use of B1 coils. Traditionally B1 coils are only used for spin tipping. We propose and demonstrate a novel approach that enables B1 coils to not only tip spins but also encode spatial information. This advance could eliminate the need for costly, complex, and noisy B0 gradient coils altogether, setting the stage for a new generation of MRI systems based solely on B1 encoding. This thesis work aims to democratize MRI by leveraging affordable Halbach magnets and innovative B1 encoding techniques. Our hope is that these advancements will lead to a redesign of MRI systems, making this life-saving technology much more accessible to under-served communities.
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    Progress Towards Development of a Desktop Oxygen Scanner for Assessing Macroencapsulated Islet Oxygenation
    (2021-08) Wang, Paul
    Islet macroencapsulation within an immunoisolation membrane is emerging as a promising new treatment for diabetes, yet providing adequate oxygenation to transplanted, encapsulated islets remains a major challenge because: 1) the islets require a specific level of oxygen (pO2) - both too little and too much oxygen impairs islet functionality and viability; 2) it is challenging to make in vivo oxygen measurements non-invasively. This thesis describes progress towards the development of a proto-type low-cost, portable, gradientless desktop MR oxygen scanner that can be used, in conjunction with an oxygen sensitive MR probe such as perfluoro-15-crown-5-ether (PFCE), to make non-invasive oxygen measurements in islet macroencapsulation devices in vivo. Novel methods are also described to accelerate oxygen measurement speed as well as to perform imaging and field mapping without using standard B0 gradients. The vision for this scanner, which is specifically designed for making pO2 measurements in macroencapsulation devices, is that one day it will be deployed in local pharmacies and supermarkets across the country, to meet the need that people with diabetes, who have received an islet macrencapsulation device implant, will have to get their oxygen measured and tuned for optimal transplant function.