Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 11 of 11 for “"RF coils"”.
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Reed-Relay Switched Tuning Circuit for Stretchable RF Coils in Low Field, Portable MRI
… of decreased image quality and greater noise interference. An RF head coil that molds to the user’s head would be able to better excite and receive signal from the subject and counteract some of the inherent disadvantages of low-field MRI. My proposed thesis will pursue the idea of using flexible, …
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Radiofrequency losses in an NMR surface coil
… loss has been investigated for a resonant NMR surface coil between 20 MHz and 400 MHz. High-field NMR (> 64 MHz) is used increasingly for human imaging and spectroscopy to achieve improved SNR and spectral resolution. RF losses in coils designed using conventional lumped-element principles, …
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ΔB₀ Field Control in High Field MRI with Local Multcoil Shim Arrays
… novel selective excitation applications. As MRI RF coils trend towards repositionable and flexible systems for their ease of use and tight-to-the-patient fit, ΔB₀ shim arrays are left behind for lack of rapid, patient-on-the-table calibration. We show an inverse problem approach with …
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Sensitivity and noise analysis of solenoidal coils for nuclear magnetic resonance microscopy
… in this thesis is to extend the analysis of RF coils used for NMR to microscopic domains. Microscopic nuclear magnetic resonance suffers from an inherently low SNR, due to the small number of nuclei available to contribute to the signal. Decreasing the size of the RF receive coil provides …
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Simulation of Electromagnetic Effects in Magnetic Resonance Imaging
… time, is employed to analyze the open RF coils in an MRI system. The FD-TD method, known for its ability to handle large and complex geometries, is applied to shielded birdcage coil analysis. Besides studying the field information inside the human head, the RF coil's resonant frequency …
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Coil performance evaluation based on electrodynamics : tools for hardware design and validation in magnetic resonance imaging
… speed limits. In parallel MRI, radiofrequency (RF) detector coil arrays are used to perform some degree of spatial encoding which complements traditional encoding using magnetic field gradients. As the acceleration factor increases, coil design becomes critical to the overall image quality. The …
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Neue unilaterale NMR-Sensoren und ihre Anwendung
… sensor and an oscillating circuit including a rf-coil to produce the orthogonal B1-field components. The complete history of the development of the new type of sensor is described, starting with the layout of the magnet system and a suitable pole piece, followed by the design of three different …
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Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging
… at 1.5T. For this purpose, radiofrequency (RF) coils were developed and a transmit/receive switch was adapted to 16.84 MHz. A 3D radial gradient echo (GRE) sequence was implemented, with a minimum echo time TEmin = 0.07ms for 1H and 0.2ms for 23Na, allowing to detect both the short (T2= …
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Development of REBCO Tapes on Non-Metallic Flexible Substrates for RF Applications
… offer a unique advantage for radio-frequency (RF) applications such as surface receiver coils for magnetic resonance imaging (MRI). Second-generation high-temperature superconductors (2G-HTS) are well developed for direct current (DC) applications. However, alternating current (AC) losses …
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Multi Spectral Data Analysis for Diagnostic Enhancement of Pediatric Spinal Cord Injury
… 4-channel neck matrix and 8-channel spine array RF coils were used for data collection. After data collection various post processing methods were used to improve the data quality. A novel ghost artifact suppression technique was implemented and tested. Initially, 168 quantitative measures of …
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Strategies for Artifact Correction and Motion Monitoring in MRI Through Innovations in Radiofrequency Coil Design
… strategies using innovations in radio-frequency (RF) coil design to address the problems that arise when these assumptions are broken. </p><p>Typically, B_0 inhomogeneities are caused by susceptibility differences at air/tissue interfaces and result in image artifacts such as geometric distortions …