scholarly journals Approaches in cooling of resistive coil-based low-field Magnetic Resonance Imaging (MRI) systems for application in low resource settings

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Faith Natukunda ◽  
Theodora M. Twongyirwe ◽  
Steven J. Schiff ◽  
Johnes Obungoloch
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Image Quality ◽  
Cooling System ◽  
Superconducting Magnets ◽  
Resonance Imaging ◽  
Middle Income ◽  
Low Field ◽  
Low Middle Income Countries ◽  
Magnetic Resonance Imaging Mri

AbstractMagnetic Resonance Imaging (MRI), a non-invasive method for the diagnosis of diverse health conditions has experienced growing popularity over other imaging modalities like ultrasound and Computer Tomography. Initially, proof-of-concept and earlier MRI systems were based on resistive and permanent magnet technology. However, superconducting magnets have long held monopoly of the market for MRI systems with their high-field (HF) strength capability, although they present high construction, installation, and siting requirements. Such stringent prerequisites restrict their availability and use in low-middle income countries. Resistive coil-based magnet, albeit low-field (LF) in capacity, represent a plausible boost for the availability and use of MRI systems in resource constrained settings. These systems are characterized by low costs coupled with substantial image quality for diagnosis of some conditions such as hydrocephalus common is such regions. However, the nature of resistive coils causes them to heat up during operation, thus necessitating a dedicated cooling system to improve image quality and enhance system longevity. This paper explores a range of cooling methods as have been applied to resistive magnets, citing their pros and cons and areas for improvement.

scholarly journals Effectiveness of low-field magnetic resonance imaging in diagnosing brachial plexus tumours in dogs – short communication

2015 ◽  
Vol 59 (2) ◽  
pp. 317-319
Author(s):  
Zbigniew Adamiak ◽  
Yauheni Zhalniarovich ◽  
Paulina Przyborowska ◽  
Joanna Głodek ◽  
Adam Przeworski
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Brachial Plexus ◽  
Resonance Imaging ◽  
Gadolinium Contrast ◽  
Gadolinium Contrast Agent ◽  
Low Field ◽  
Mri Sequences ◽  
Magnetic Resonance Imaging Mri ◽  
Brachial Plexus Tumours

AbstractThe aim of the study was to identify magnetic resonance imaging (MRI) sequences that contribute to a quick and reliable diagnosis of brachial plexus tumours in dogs. The tumours were successfully diagnosed in 6 dogs by the MRI with the use of SE, FSE, STIR, Turbo 3 D, 3D HYCE, and GE sequences and the gadolinium contrast agent

Monitoring a typical fermentation process of natto by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) techniques

2016 ◽  
Vol 8 (39) ◽  
pp. 7135-7140 ◽  
Author(s):  
Jing Wu ◽  
Yanru Li ◽  
Xingsheng Gao
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Fermentation Process ◽  
Resonance Imaging ◽  
Low Field ◽  
Magnetic Resonance Imaging Mri ◽  
Lf Nmr ◽  
Nuclear Magnetic

Unique insights into the monitoring of a typical fermentation process of natto based on low field nuclear magnetic resonance (LF-NMR) associated with magnetic resonance imaging (MRI).

Evaluation of Magnetic Resonance Imaging Responsiveness in Active Psoriatic Arthritis at Multiple Timepoints during the First 12 Weeks of Antitumor Necrosis Factor Therapy

2015 ◽  
Vol 43 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Marie Feletar ◽  
Stephen Hall ◽  
Paul Bird
Keyword(s):  
Magnetic Resonance Imaging ◽  
Psoriatic Arthritis ◽  
Magnetic Resonance ◽  
High Field ◽  
Early Response ◽  
Resonance Imaging ◽  
Low Field ◽  
Low Field Mri ◽  
Magnetic Resonance Imaging Mri ◽  
Necrosis Factor

Objective.To assess the responsiveness of high- and low-field extremity magnetic resonance imaging (MRI) variables at multiple timepoints in the first 12 weeks post-antitumor necrosis factor (anti-TNF) therapy initiation in patients with psoriatic arthritis (PsA) and active dactylitis.Methods.Twelve patients with active PsA and clinical evidence of dactylitis involving at least 1 digit were recruited. Patients underwent sequential high-field conventional (1.5 Tesla) and extremity low-field MRI (0.2 Tesla) of the affected hand or foot, pre- and postgadolinium at baseline (pre-TNF), 2 weeks (post-TNF), 6 weeks, and 12 weeks. A blinded observer scored all images on 2 occasions using the PsA MRI scoring system.Results.Eleven patients completed the study, but only 6 patients completed all high-field and low-field MRI assessments. MRI scores demonstrated rapid response to TNF inhibition with score reduction in tenosynovitis, synovitis, and osteitis at 2 weeks. Intraobserver reliability was good to excellent for all variables. High-field MRI demonstrated greater sensitivity to tenosynovitis, synovitis, and osteitis and greater responsiveness to change posttreatment. Treatment responses were maintained to 12 weeks.Conclusion.This study demonstrates the use of MRI in detecting early response to biologic therapy. MRI variables of tenosynovitis, synovitis, and osteitis demonstrated responsiveness posttherapy with high-field scores more responsive to change than low-field scores.

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.

scholarly journals Inflammatory and post-inflammatory lesions in the sacroiliac joints and lumbar spine according to magnetic resonance imaging in patients with early axial spondyloarthritis

2019 ◽  
Vol 57 (1) ◽  
pp. 28-32 ◽  
Author(s):  
D. G. Rumyantseva ◽  
Sh. Erdes ◽  
A. V. Smirnov
Keyword(s):  
Magnetic Resonance Imaging ◽  
Lumbar Spine ◽  
Magnetic Resonance ◽  
Disease Duration ◽  
Resonance Imaging ◽  
Sacroiliac Joints ◽  
Low Field ◽  
Low Field Mri ◽  
Magnetic Resonance Imaging Mri ◽  
Inflammatory Changes

Investigation of the evolution of early axial spondylitis (axSP) is now of great importance especially before the appearance of reliable radiological signs of ankylosing spondylitis (AS). Of particular interest is the assessment of inflammatory and post-inflammatory changes in the sacroiliac joints (SJ) and in the spine using magnetic resonance imaging (MRI).The aimof the study was to analyze inflammatory foci in bone according to MRI in the area of SJ and lumbar spine (LS) in patients with early axSP.Material and methods.The study involved the patients of the Moscow cohort CORSAIR (Early Spondyloarthritis Cohort), which was formed in V.A. Nasonova Research Institute of Rheumatology. Low field MRI of SJ and LS was carried out in all patients at inclusion in the study in the T1 and STIR modes.Results and discussion.SJ MRI most often (34.1%) revealed combined foci of inflammation (active and chronic sacroiliitis – SI), 32.9% of patients showed signs of only chronic, rarely – only active SI (19.5%). In a few cases, MRI showed inflammatory changes in LS, which were regarded as active and chronic spondylitis. In patients with a disease duration of up to 1 year, signs of active SI were more common according to MRI than in patients with a longer duration of the disease (30.0 and 14.4%, respectively; p<0.05). All active foci of inflammation (with or without signs of chronic SI) were significantly more frequently detected in patients with AS than in non-radiological axSP (NR-axSP; 61.6% and 44.2%, respectively; p<0.05). The overall incidence of chronic spondylitis (in combination with or without active spondylitis) in patients with AS was higher than in NR-axSP(13.9% and 5.8%, respectively; p<0.05).Conclusion.Patients with AS more often have active lesions at MRI of SJ and chronic ones at MRI of LS than patients with NR-axSP

Advances in Magnetic Resonance Imaging of the Pelvis at 0.15 Tesla

1986 ◽  
Vol 27 (4) ◽  
pp. 369-377 ◽  
Author(s):  
D. J. Hamlin ◽  
H. Pettersson ◽  
J. O. Johnson ◽  
J. R. Fitzsimmons
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
Low Field ◽  
Radiofrequency Coils ◽  
Magnetic Resonance Imaging Mri ◽  
Mass Lesions

The recent development of improved commercial radiofrequency coils and multiecho, multislice software for low field strength magnetic resonance systems has markedly increased the clinical utility of magnetic resonance imaging (MRI) of the pelvis at low field strengths. An evaluation of 70 patients with a variety of pelvic lesions and 14 normal volunteers who were studied using 0.15 T resistive magnet scanner revealed that anatomic structures and a variety of mass lesions could be clearly depicted in transaxial, sagittal and coronal planes using this updated system. Accurate characterization of lesions was possible in many instances using T2 weighted multiecho scans with echo time (TE) ranging from 30 ms to 120 ms (45 ms–180 ms using a reduced bandwidth technique). T1 weighted multislice scans demonstrated anatomic structures to best adantage and calculation of T1 and T2 relaxation times frequently facilitated more accurate differential diagnosis, particularly in the case of ovarian lesions.

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