Approaching ultimate intrinsic specific absorption rate in radiofrequency shimming using high-permittivity materials at 7 Tesla.

ABSTRACT:

Purpose

The aim of this study was to evaluate the effect of integrated high-permittivity materials (HPMs) on excitation homogeneity and global specific absorption rate (SAR) for transmit arrays at 7T.

Methods

A rapid electrodynamic simulation framework was used to calculate L-curves associated with excitation of a uniform 2D profile in a dielectric sphere. We used ultimate intrinsic SAR as an absolute performance reference to compare different transmit arrays in the presence and absence of a layer of HPM. We investigated the optimal permittivity for the HPM as a function of its thickness, the sample size, and the number of array elements.

Results

Adding a layer of HPM can improve the performance of a 24-element array to match that of a 48-element array without HPM, wh

SUBMITTER: Haemer GG 

PROVIDER: S-EPMC5876092 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature