A CRLH zeroth-order resonant antenna (ZORA) with high near-field polarization purity used as an RF coil element for ultra high field MRI"
In: Metamaterials 2010 : 4th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics ; Karlsruhe (Germany), 13. - 16.9.2010
Karlsruhe (2010), S. 92-94
Buchaufsatz / Kapitel / Fach: Elektrotechnik
A CRLH zeroth-order resonant antenna (ZORA) with near-field performance optimized for 7 Tesla magnetic resonance imaging (MRI) is presented. Due to its zeroth-order resonance mode, occurring at the frequency where the phase constant is zero, the ZORA supports a highly uniform field, as required for MRI. Moreover, it exhibits a favorable longitudinal scalability for RF coil lengths ranging from 10 cm up to 50 cm and higher. Compared to previous implementations, the proposed ZORA uses SMD chip components placed at the back of the radiator to provide the CRLH shunt resonator elements instead of transverse stubs. As a result, the longitudinal magnetic field contributions are essentially suppressed and high transverse magnetic field purity, allowing high-resolution MRI, is achieved. As another consequence, the transverse size of the antenna is dramatically reduced, which is particularly beneficial for head or brain imaging, where undisturbed eye-contact with the patient is required in functional MRI. Furthermore the proposed ZORA features a low profile of only 2.3 mm, and could therefore be integrated behind the inner bore dielectric cover.