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Contains fulltext : 291141.pdf (Publisher’s version ) (Closed access) 01 april 2023

Recently multi-channel RF coils based on several longitudinally oriented strip-line elements have been successfully applied in ultra-high field MRI. Among the different utilized strip-line approaches, the symmetrically fed dipole RF coil element initially presented in [1] which was terminated by two meander in [2, 3] seems to be one of the most promising candidates. This 25 cm long dipole element is slightly longer than half a wavelength (“λ/2-plus”) and is therefore not intrinsically eigen-resonant. In [4] the first homogeneous “from top to toe” MR image at 7 T has been scanned with the help of a whole-body coil array consisting of 16 of these meander elements. The authors took 28 successive overlapping scans, each with a longitudinal extend of approx. 25 cm. On the basis of this λ/2-plus-approach we developed a longitudinally extended coil element which exhibits a nearly full-wavelength resonant current distribution (“λ-minus”) with two distinct improvements – an RF field of view (FOV) that is maximized due to the longer extent and a lowered peak SAR10g due to a more appropriate two-peak electric field distribution.

Preliminary experimental magnetic resonance imaging (MRI) results based on a novel composite right/lefthanded (CRLH) zeroth-order resonant coil (ZORC) are presented. These results demonstrate, using an homogeneous flat phantom emulating the human body, that the ZORC can achieve very large fields of view, corresponding to the length of the ZOR structure, which is of approximately 30 cm in the prototype presented.

Studienarbeit im Fachgebiet Allgemeine und Theoretische Elektrotechnik (ATE), Universität Duisburg-Essen, Nov. 2006.