Robust, susceptibility-matched NMR probes for compensation of magnetic field imperfections in magnetic resonance imaging (MRI)

2008 ◽  
Vol 145-146 ◽  
pp. 139-146 ◽  
Author(s):  
P. Sipilä ◽  
D. Lange ◽  
S. Lechner ◽  
W. Löw ◽  
P. Gross ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
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.

Fabrication of multifunctional ferric oxide nanoparticles for tumor-targeted magnetic resonance imaging and precise photothermal therapy with magnetic field enhancement

2017 ◽  
Vol 5 (43) ◽  
pp. 8554-8562 ◽  
Author(s):  
Jiaxin Liu ◽  
Hongda Chen ◽  
Yu Fu ◽  
Xiaodong Li ◽  
Yixin Chen ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Photothermal Therapy ◽  
Field Enhancement ◽  
Resonance Imaging ◽  
System P ◽  
Weighted Magnetic Resonance Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
Magnetic Field Enhancement

Fe2O3@PDA-affibody integrates T2-weighted magnetic resonance imaging (MRI), tumor-targeting, and magnetic field (MF)-enhanced photothermal therapy (PTT) functionalities into an all-in-one system.

Safety and efficacy assessment of MRI in cochlear implant patients with retained magnets

2021 ◽  
Vol 20 (3) ◽  
pp. 8-14
Author(s):  
V. V. Dvoryanchikov ◽  
◽  
V. E. Kuzovkov ◽  
S. Kh. Tsutsieva ◽  
S. V. Levin ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Cochlear Implants ◽  
Resonance Imaging ◽  
Diagnostic Efficacy ◽  
Negative Effect ◽  
Efficacy Assessment ◽  
Magnetic Resonance Imaging Mri ◽  
Bilateral Sensorineural Hearing Loss

Most patients with CI need to undergo radiation diagnostics during their lifetime, including magnetic resonance imaging (MRI) and computed tomography (CT). Modern cochlear implants are currently compatible with MRI up to 1.5 T. However, clinics conducting magnetic resonance imaging studies may refuse to diagnose. This is due to the fact that during the study, the MRI scanner will act on the magnet of the implant and this can lead to such complications as migration of the implant, its demagnetization, and pain. These doubts determined the goal of our study - to assess the safety and effectiveness of magnetic resonance imaging (MRI) with a magnetic field power of 1.5 T in patients with cochlear implants (CI). We analyzed MR images of 11 patients who were followed up at the St. Petersburg Research Institute of Ear, Throat, Nose and Speech from 2014 to 2020, diagnosed with bilateral sensorineural hearing loss, grade IV, condition after CI. A questionnaire was conducted to determine the side effects of the study and to assess the diagnostic effectiveness of the method by several radiologists. In order to prevent possible complications, an external, tight-fitting pressure bandage was applied to all patients, and a plastic splint was installed in the projection of the implant in the bandage. During the study, the orientations of the magnetic fields of the MRI scanner (B0) and the implant (B1) were considered. The analysis of the obtained results showed that the MRI procedure with a magnetic field power of 1.5 T in patients with CI was not accompanied by any complications for patients and a negative effect on the implant. It is important to note that the diagnostic efficacy of the MRI results was maintained.

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