  Higher frequencies and shorter wavelengths present significant design issues
at ultra-high fields, making multi-channel array setup a critical component for
ultra-high field MR imaging. The requirement for multi-channel arrays, as well
as ongoing efforts to increase the number of channels in an array, are always
limited by the major issue known as inter-element coupling. This coupling
affects the current and field distribution, noise correlation between channels,
and frequency of array elements, lowering imaging quality and performance. To
realize the full potential of UHF MRI, we must ensure that the coupling between
array elements is kept to a minimum. High-impedance coils allow array systems
to completely realize their potential by providing optimal isolation while
requiring minimal design modifications. These minor design changes, which
demand the use of low capacitance on the conventional loop to induce elevated
impedance, result in a significant safety hazard that cannot be overlooked.
High electric fields are formed across these low capacitance lumped elements,
which may result in higher SAR values in the imaging subject, depositing more
power and, ultimately, providing a greater risk of tissue heating-related
injury to the human sample. We propose an innovative method of utilizing
high-dielectric material to effectively reduce electric fields and SAR values
in the imaging sample while preserving the B1 efficiency and inter-element
decoupling between the array elements to address this important safety concern
with minimal changes to the existing array design comprising high-impedance
coils.
