Automated Positioning System for Benchtop Characterization of Multinuclear RF Coils
Abstract
Radio frequency (RF) coils are utilized in Magnetic Resonance Imaging (MRI) to acquire images of a subject. The design of RF coils is a significant factor in the quality of the image produced encouraging their construction to be personalized to the subject and fine-tuned to produce an acceptable image. Consequently, RF coils are designed in a variety of sizes and can exhibit different behaviors depending on their application. For all RF coils, it is important to ensure that the expected behavior is exhibited by the coils. Verification is performed by benchtop testing that involves S21 measurements with a network analyzer, where a signal is transmitted through the coil in question and a loop probe measures the magnitude of the transmit magnetic field (B1+). The effectiveness of the coil for the desired frequency with respect to the spatial location of the measurements is evaluated from the data acquired and can be visualized by generating a field map of the B1+ field. Performing benchtop measurements has proven to be a time-consuming process that can produce inconsistent results when performed by hand as it is difficult to ensure that measurements are taken in equal spacing. To overcome this issue, companies have created commercial models that can perform these measurements, but these models are costly. Other automated systems exist but they are limited to taking measurements for one frequency at a time or taking measurements for the B0 field, or both. This thesis proposes an alternative system that allows for measurements to be performed in an automated or manual manner with precision and the capability of measuring multiple frequencies while being less expensive than existing solutions in the market. The effectiveness of this solution was evaluated by creating B1+ field maps for a birdcage coil and a loop coil using the various functions provided by the system and comparing the results to the expected behavior of the B1+ field for these coils. Results demonstrated that the system provides repeatable measurements, and it is capable of measuring coils of different geometries and with multiple frequencies while also providing a manual option for the user to utilize.
Citation
Posso, Jeanpaul (2023). Automated Positioning System for Benchtop Characterization of Multinuclear RF Coils. Undergraduate Research Scholars Program. Available electronically from https : / /hdl .handle .net /1969 .1 /200261.