Radiative MRI Coil Design Using Parasitic Scatterers: MRI Yagi
Juan D. Sánchez-Heredia , Johan Avendal, Adnan Bibic, and Buon Kiong Lau
IEEE Transactions on Antennas and Propagation
Vol. 66, No. 3,
1st January 0001
Electromagnetic propagation in absorbing media, magnetic resonance imaging (MRI), specific absorption rate (SAR), Yagi–Uda antennas
Conventionally, radio frequency (RF) coils used for magnetic resonance imaging (MRI) are electrically small and designed for near-field operation. Therefore, existing antenna design techniques are mostly irrelevant for RF coils. However, the use of higher frequencies in ultrahigh field MRI allows for antenna design techniques to be adapted to RF coil designs. This communication proposes the use of parasitic scatterers to improve the performance of an existing 7T MRI coil called the single-sided adapted dipole (SSAD) antenna. The results reveal that scatterers arranged in a Yagi fashion can be applied to reduce local specific absorption rate maxima of a reference SSAD by 40% with only a 6% decrease in the propagated B+ 1 field at the tissue depth of 15 cm. The higher directivity of the proposed design also decreases the coupling with additional elements, making this antenna suitable for use in highdensity arrays. These findings show the potential of parasitic scatterers as an effective method to improve the performance of existing radiative MRI coils.
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