scholarly journals Electromagnetic Simulation of Influence of Metamaterial for Magnetic Resonance Imaging at 3T

2016 ◽  
Vol 848 ◽  
pp. 347-350
Author(s):  
Chao Luo ◽  
Xiao Qing Hu ◽  
Chun Lai Li ◽  
Xiao Chen ◽  
Xiao Liang Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Simulation Software ◽  
Electromagnetic Simulation ◽  
Rf Coil ◽  
Resonance Imaging ◽  
Receiving Coil ◽  
Magnetic Resonance Imaging Mri ◽  
Rf Magnetic Field

This paper presents an approach to investigate the influence of metamaterial to radio-frequency (RF) magnetic field in magnetic resonance imaging (MRI) at 3T. The variety of magnetic fields of RF receiving coil was calculated using the commercial electromagnetic simulation software (CST). The simulation results demonstrate that the transmitting and receiving magnetic field (B1+ and B1-) can be enhanced when the metamaterial is inserted into the RF coil, suggesting that the metamaterial has potential in MRI applications at 3T.

Radial magnetic resonance imaging (MRI) using a rotating radiofrequency (RF) coil at 9.4 T

2017 ◽  
Vol 31 (2) ◽  
pp. e3860 ◽  
Author(s):  
Mingyan Li ◽  
Ewald Weber ◽  
Jin Jin ◽  
Thimo Hugger ◽  
Yasvir Tesiram ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Rf Coil ◽  
Resonance Imaging ◽  
Magnetic Resonance Imaging Mri

scholarly journals B0-Shimming Methodology for Affordable and Compact Low-Field Magnetic Resonance Imaging Magnets

2021 ◽  
Vol 9 ◽  
Author(s):  
Konstantin Wenzel ◽  
Hazem Alhamwey ◽  
Tom O’Reilly ◽  
Layla Tabea Riemann ◽  
Berk Silemek ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Point Of Care ◽  
Low Cost ◽  
Field Measurements ◽  
Target Volume ◽  
Resonance Imaging ◽  
Low Field ◽  
Magnetic Resonance Imaging Mri

Low-field (B0 < 0.2 T) magnetic resonance imaging (MRI) is emerging as a low cost, point-of-care alternative to provide access to diagnostic imaging technology even in resource scarce environments. MRI magnets can be constructed based on permanent neodymium-iron-boron (NdFeB) magnets in discretized arrangements, leading to substantially lower mass and costs. A challenge with these designs is, however, a good B0 field homogeneity, which is needed to produce high quality images free of distortions. In this work, we describe an iterative approach to build a low-field MR magnet based on a B0-shimming methodology using genetic algorithms. The methodology is tested by constructing a small bore (inner bore diameter = 130 mm) desktop MR magnet (<15 kg) at a field strength of B0 = 0.1 T and a target volume of 4 cm in diameter. The configuration consists of a base magnet and shim inserts, which can be placed iteratively without modifying the base magnet assembly and without changing the inner dimensions of the bore or the outer dimensions of the MR magnet. Applying the shims, B0 field inhomogeneity could be reduced by a factor 8 from 5,448 to 682 ppm in the target central slice of the magnet. Further improvements of these results can be achieved in a second or third iteration, using more sensitive magnetic field probes (e.g., nuclear magnetic resonance based magnetic field measurements). The presented methodology is scalable to bigger magnet designs. The MR magnet can be reproduced with off-the-shelf components and a 3D printer and no special tools are needed for construction. All design files and code to reproduce the results will be made available as open source hardware.

A trail of artificial vestibular stimulation: electricity, heat, and magnet

2012 ◽  
Vol 108 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Aasef G. Shaikh
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Semicircular Canals ◽  
Vestibular Stimulation ◽  
Clinical Neurology ◽  
Ion Currents ◽  
Resonance Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
The Magnetic Field

The interaction between the magnetic field of a magnetic resonance imaging (MRI) machine and ion currents within the inner-ear endolymph results in a Lorentz force. This force produces a pressure that pushes on the cupula within the semicircular canals causing nystagmus and vertigo. Here I discuss several implications of this unique and noninvasive way to stimulate the vestibular system in experimental neurophysiology and clinical neurology.

scholarly journals Investigating the influence of dielectric pads in 7T magnetic resonance imaging – simulated and experimental assessment

2020 ◽  
Vol 6 (3) ◽  
pp. 24-27
Author(s):  
Maíra M. Garcia ◽  
Khallil T. Chaim ◽  
Maria C. G. Otaduy ◽  
Andreas Rennings ◽  
Daniel Erni ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Electric Fields ◽  
Dielectric Constants ◽  
Rf Coil ◽  
Resonance Imaging ◽  
Magnetic Components ◽  
Magnetic Resonance Imaging Mri ◽  
High Dielectric ◽  
Ultrahigh Fields

AbstractDipole radiofrequency (RF) elements have been successfully used to compose multi-channel RF coils for ultrahigh fields (UHF) magnetic resonance imaging (MRI). As magnetic components of RF fields (B1) can be very inhomogeneous at UHF (B0≥7T), dielectric pads with high dielectric constants were proposed to improve the B1 efficiency and homogeneity [1]. Dielectric pads can be used as a passive B1 shimmimg technique thanks to inducing a strong secondary magnetic field in their vicinity. The use of such dielectric pads affect not only the B1 field but also the electric field. This in turn affects the specific absorption rate (SAR) and consequently the temperature distribution inside the patient’s body. To study these effects, a 29 cm-long transmission dipole RF coil element terminated by two meander was used for 7T MRI [2]. Using a cylindrical agarose-gel phantom, numerical and experimental results were analyzed with respect to homogeneity and amplitude of the magnetic and electric fields generated by the RF element in various configurations with and without dielectric pads. Calculated and measured B1 results were cross-checked and found to be in good agreement. When using dielectric pads B1 homogeneity and magnitude increase in regions where it was previously weak or insufficient. Calculations suggest that SAR distribution will change when using the pads.

Sign in / Sign up

Export Citation Format

Share Document