Radiofrequency safety of high permittivity pads in MRI—Impact of insulation material

Purpose: High permittivity dielectric pads are known to be effective for tailoring the RF field and improving image quality in high field MRI. Despite a number of studies reporting benign specific absorption rate (SAR) effects, their “universal” safety remains an open concern. In this work, we evaluate the impact of the insulation material in...

First-Order Induced Current Density Imaging and Electrical Properties Tomography in MRI

In this paper, we present an efficient dedicated electrical properties tomography (EPT) algorithm (called first-order current density EPT ) that exploits the particular radio frequency field structure, which is present in the midplane of a birdcage coil, to reconstruct conductivity and permittivity maps in this plane from B ^ + 1 data. The...

High-Permittivity Pad Design for Dielectric Shimming in Magnetic Resonance Imaging Using Projection-Based Model Reduction and a Nonlinear Optimization Scheme

Inhomogeneities in the transmit radio frequency magnetic field ( {\text{B}}-{1}^{+} ) reduce the quality of magnetic resonance (MR) images. This quality can be improved by using high-permittivity pads that tailor the {\text{B}}-{1}^{+} fields. The design of an optimal pad is application-specific and not straightforward and would therefore...

3-D Contrast Source Inversion-Electrical Properties Tomography

Contrast source inversion – electrical properties tomography (CSI-EPT) is an iterative reconstruction method to retrieve the electrical properties (EPs) of tissues from MR data. The method is based on integral representations of the electromagnetic (EM) field and has been shown to allow EP reconstructions of small structures as...