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Low field MRI

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https://www.readbyqxmd.com/read/28638673/monitoring-of-cellular-changes-in-the-bone-marrow-following-pth-1-34-treatment-of-ovx-rats-using-a-portable-stray-field-nmr-scanner
#1
Inbar Hillel, Itzhak Binderman, Yifat Sarda, Uri Nevo
Osteoporosis is characterized by reduction in trabecular bone in conjunction with increased marrow cell adiposity. While these changes occur within weeks, monitoring of treatment efficacy as performed by DEXA is sensitive only to long-term changes. MRI is sensitive to bone marrow changes but is less affordable. In a recent study, we have shown that a stray-field NMR can monitor bone marrow cellular changes that are related to osteoporosis. Objectives. To demonstrate sensitivity of a low-field tabletop NMR scanner to bone marrow dynamics following hormonal treatment in rats...
2017: Journal of Osteoporosis
https://www.readbyqxmd.com/read/28632688/high-quality-3-dimensional-1h-magnetic-resonance-spectroscopic-imaging-of-the-prostate-without-endorectal-receive-coil-using-a-semi-laser-sequence
#2
Nassim Tayari, Isabell K Steinseifer, Kirsten M Selnæs, Tone F Bathen, Marnix C Maas, Arend Heerschap
OBJECTIVES: Inclusion of 3-dimensional H magnetic resonance spectroscopic imaging (3D-H-MRSI) in routine multiparametric MRI of the prostate requires good quality spectra and easy interpretable metabolite maps of the whole organ obtained without endorectal coil in clinically feasible acquisition times. We evaluated if a semi-LASER pulse sequence with gradient offset independent adiabaticity refocusing pulses (GOIA-sLASER) for volume selection can meet these requirements. MATERIALS AND METHODS: Thirteen patients with suspicion of prostate cancer and 1 patient known to have prostate cancer were examined at 3 T with a multichannel body-receive coil...
June 19, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/28631204/adaptive-step-size-lms-improves-ecg-detection-during-mri-at-1-5-and-3%C3%A2-t
#3
André Guillou, Jean-Marc Sellal, Sarah Ménétré, Grégory Petitmangin, Jacques Felblinger, Laurent Bonnemains
OBJECTIVE: We describe a new real-time filter to reduce artefacts on electrocardiogram (ECG) due to magnetic field gradients during MRI. The proposed filter is a least mean square (LMS) filter able to continuously adapt its step size according to the gradient signal of the ongoing MRI acquisition. MATERIALS AND METHODS: We implemented this filter and compared it, within two databases (at 1.5 and 3 T) with over 6000 QRS complexes, to five real-time filtering strategies (no filter, low pass filter, standard LMS, and two other filters optimized within the databases: optimized LMS, and optimized Kalman filter)...
June 19, 2017: Magma
https://www.readbyqxmd.com/read/28628224/human-exposure-to-power-frequency-magnetic-fields-up-to-7-6%C3%A2-mt-an-integrated-eeg-fmri-study
#4
Julien Modolo, Alex W Thomas, Alexandre Legros
We assessed the effects of power-line frequency (60 Hz in North America) magnetic fields (MF) in humans using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Twenty-five participants were enrolled in a pseudo-double-blind experiment involving "real" or "sham" exposure to sinusoidal 60 Hz MF exposures delivered using the gradient coil of an MRI scanner following two conditions: (i) 10 s exposures at 3 mT (10 repetitions); (ii) 2 s exposures at 7.6 mT (100 repetitions)...
June 19, 2017: Bioelectromagnetics
https://www.readbyqxmd.com/read/28627764/illustration-of-a-simple-route-to-generate-strong-carbon-13-nmr-signals-that-are-detectable-for-several-minutes
#5
Simon Duckett, Soumya Roy, Philip Norcott, Peter J Rayner, Gary Gr Green
Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) suffer from low sensitivity and limited nuclear spin memory lifetimes. While hyperpolarization techniques increase sensitivity there is also a desire to increase relaxation times to expand the range of applications addressable by these methods. Here we demonstrate a route to create hyperpolarized magnetization in ¹³C nuclear spin pairs that last much longer than normal lifetimes by storage in a singlet state. By combining molecular design and low-field storage with para-hydrogen derived hyperpolarization we achieve more than three-orders of signal amplification relative to equilibrium Zeeman polarization and an order of magnitude extension in state lifetime...
June 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28624085/multi-scale-nmr-and-mri-approaches-to-characterize-starchy-products
#6
R Kovrlija, C Rondeau-Mouro
This review deals with the use of Nuclear Magnetic Resonance techniques to monitor the behavior of starch as well as the migration and distribution of water during the processing or storage of starchy matrices. The aim is to emphasize the potentials of NMR techniques for the quantitative characterization of water transfers in starch-water systems on different length scales. Relaxation and self-diffusion experiments using low-field NMR spectrometry provided important information on the relationship between water dynamics and the microscopic organization of starch granules at various temperatures and water contents...
December 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28622410/accuracy-of-deformable-image-registration-on-magnetic-resonance-images-in-digital-and-physical-phantoms
#7
Rachel B Ger, Jinzhong Yang, Yao Ding, Megan C Jacobsen, Clifton D Fuller, Rebecca M Howell, Heng Li, R Jason Stafford, Shouhao Zhou, Laurence E Court
PURPOSE: Accurate deformable image registration is necessary for longitudinal studies. The error associated with commercial systems has been evaluated using computed tomography (CT). Several in-house algorithms have been evaluated for use with magnetic resonance imaging (MRI), but there is still relatively little information about MRI deformable image registration. This work presents an evaluation of two deformable image registration systems, one commercial (Velocity) and one in-house (demons-based algorithm), with MRI using two different metrics to quantify the registration error...
June 16, 2017: Medical Physics
https://www.readbyqxmd.com/read/28614824/compact-intraoperative-mri-stereotactic-accuracy-and-future-directions
#8
Daniel Markowitz, Dishen Lin, Sussan Salas, Nina Kohn, Michael Schulder
BACKGROUND: Intraoperative imaging must supply data that can be used for accurate stereotactic navigation. This information should be at least as accurate as that acquired from diagnostic imagers. OBJECTIVES: The aim of this study was to compare the stereotactic accuracy of an updated compact intraoperative MRI (iMRI) device based on a 0.15-T magnet to standard surgical navigation on a 1.5-T diagnostic scan MRI and to navigation with an earlier model of the same system...
June 15, 2017: Stereotactic and Functional Neurosurgery
https://www.readbyqxmd.com/read/28604617/targeted-magnetic-nanotheranostics-of-cancer
#9
REVIEW
Irina Belyanina, Olga Kolovskaya, Sergey Zamay, Ana Gargaun, Tatiana Zamay, Anna Kichkailo
Current advances in targeted magnetic nanotheranostics are summarized in this review. Unique structural, optical, electronic and thermal properties of magnetic materials in nanometer scale are attractive in the field of biomedicine. Magnetic nanoparticles functionalized with therapeutic molecules, ligands for targeted delivery, fluorescent and other chemical agents can be used for cancer diagnostic and therapeutic purposes. High selectivity, small size, and low immunogenicity of synthetic nucleic acid aptamers make them attractive delivery agents for therapeutic purposes...
June 12, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28602943/in-vivo-b0-field-shimming-methods-for-mri-at-7-t
#10
Jason P Stockmann, Lawrence L Wald
Functional MRI (fMRI) at 7 T and above provides improved Signal-to-Noise Ratio and Contrast-to-Noise Ratio compared to 3 T acquisitions. In addition to the beneficial effects on spin polarization and magnetization of deoxyhemoglobin, the increased applied field also further magnetizes air and tissue. While the magnets themselves typically provide a static B0 field with sufficient spatial homogeneity, the diamagnetism of tissue and the paramagnetism of air causes local field deviations inside the human head...
June 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/28589726/tri-needle-coaxial-electrospray-engineering-of-magnetic-polymer-yolk-shell-particles-possessing-dual-imaging-modality-multiagent-compartments-and-trigger-release-potential
#11
Chunchen Zhang, Zhi-Cheng Yao, Qiuping Ding, James J Choi, Zeeshan Ahmad, Ming-Wei Chang, Jing-Song Li
Particulate platforms capable of delivering multiple actives as well as providing diagnostic features have gained considerable interest over the last few years. In this study, magnetic polymer yolk-shell particles (YSPs) were engineered using a tri-needle coaxial electrospraying technique enabling dual-mode (ultrasonic and magnetic resonance) imaging capability with specific multidrug compartments via an advanced single-step encapsulation process. YSPs comprised magnetic Fe3O4 nanoparticles (MNPs) embedded in the polymeric shell, an interfacing oil layer, and a polymeric core (i...
June 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28577904/merging-computational-fluid-dynamics-and-4d-flow-mri-using-proper-orthogonal-decomposition-and-ridge-regression
#12
Ali Bakhshinejad, Ahmadreza Baghaie, Alireza Vali, David Saloner, Vitaliy L Rayz, Roshan M D'Souza
Time resolved phase-contrast magnetic resonance imaging 4D-PCMR (also called 4D Flow MRI) data while capable of non-invasively measuring blood velocities, can be affected by acquisition noise, flow artifacts, and resolution limits. In this paper, we present a novel method for merging 4D Flow MRI with computational fluid dynamics (CFD) to address these limitations and to reconstruct de-noised, divergence-free high-resolution flow-fields. Proper orthogonal decomposition (POD) is used to construct the orthonormal basis of the local sampling of the space of all possible solutions to the flow equations both at the low-resolution level of the 4D Flow MRI grid and the high-level resolution of the CFD mesh...
June 14, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28555348/-magnetic-resonance-imaging-recent-studies-on-biological-effects-of-static-magnetic-and-high%C3%A2-frequency-electromagnetic-fields
#13
REVIEW
B Pophof, G Brix
PROBLEM: During the last few years, new studies on biological effects of strong static magnetic fields and on thermal effects of high-frequency electromagnetic fields used in magnetic resonance imaging (MRI) were published. Many of these studies have not yet been included in the current safety recommendations. METHOD: Scientific publications since 2010 on biological effects of static and electromagnetic fields in MRI were researched and evaluated. RESULTS: New studies confirm older publications that have already described effects of static magnetic fields on sensory organs and the central nervous system, accompanied by sensory perceptions...
May 29, 2017: Der Radiologe
https://www.readbyqxmd.com/read/28543921/correlations-of-low-field-nmr-and-variable-field-nmr-parameters-with-osteoarthritis-in-human-articular-cartilage-under-load
#14
Erik Rössler, Carlos Mattea, Simo Saarakkala, Petri Lehenkari, Mikko Finnilä, Lassi Rieppo, Sakari Karhula, Miika T Nieminen, Siegfried Stapf
NMR experiments carried out at magnetic fields below 1 T provide new relaxation parameters unavailable with conventional clinical scanners. Contrast of T1 generally becomes larger towards low fields, as slow molecular reorientation processes dominate relaxation at the corresponding Larmor frequencies. This advantage has to be considered in the context of lower sensitivity and frequently reduced spatial resolution. The layered structure of cartilage is one example where a particularly strong variation of T1 across the tissue occurs, being affected by degenerative diseases such as osteoarthritis (OA)...
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28531809/multifocal-visual-evoked-potentials-in-optic-neuritis-and-multiple-sclerosis-a-review
#15
REVIEW
Gorm Pihl-Jensen, Mathias Falck Schmidt, Jette Lautrup Frederiksen
Multifocal visual evoked potential (mf-VEP) represents a new approach to the classical full field (ff-)VEP with separate responses from up to 60 sectors of the visual field. A thorough literature survey of the use of mf-VEP in optic neuritis (ON) and multiple sclerosis (MS) is presented (38 published studies were retrieved). Mf-VEP provides direct topographical information of specific lesions and facilitates investigations on structural-functional correlations thus providing new methods for exploring the interplay between demyelination, atrophy and remyelination in MS...
July 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28528845/comparison-of-3t-and-7t-asl-techniques-for-concurrent-functional-perfusion-and-bold-studies
#16
Dimo Ivanov, Anna Gardumi, Roy A M Haast, Josef Pfeuffer, Benedikt A Poser, Kâmil Uludağ
Arterial spin labeling (ASL) is the primary non-invasive MRI approach to measure baseline cerebral blood flow (CBF) in healthy subjects and patients. ASL also allows concurrent functional BOLD signal and CBF measurements, but the latter typically suffer from low contrast-to-noise (CNR) ratio. Ultra-high-field imaging significantly boosts BOLD signal CNR. However, it is contested whether also CBF CNR benefits from increasing magnetic field strength, especially given that technical challenges related to field inhomogeneities and power deposition constraints exist...
May 19, 2017: NeuroImage
https://www.readbyqxmd.com/read/28528099/investigation-on-water-status-and-distribution-in-broccoli-and-the-effects-of-drying-on-water-status-using-nmr-and-mri-methods
#17
Fangfang Xu, Xin Jin, Lu Zhang, Xiao Dong Chen
Many quality attributes of food products are influenced by the water status and the microstructure. Low-field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) methods are applied to non-destructively monitor the water status and structure of food. The aim of this study is to investigate the water status and distribution inside broccoli tissues and the effects of hot-air drying on the water status by using NMR and MRI methods. Transverse relaxation times (T2) provide the information of water status and water distribution...
June 2017: Food Research International
https://www.readbyqxmd.com/read/28516447/metacarpophalangeal-joint-injury-patterns-on-magnetic-resonance-imaging-a-comparison-in-racing-standardbreds-and-thoroughbreds
#18
Julien Olive, Nicolas Serraud, Thibault Vila, Jean-Philippe Germain
The metacarpal condyle has received extensive attention as a predominant site of overload arthropathy in racehorses. However, detailed descriptions of MRI lesion patterns for the metacarpophalangeal joint and comparisons between types of racing horses are currently lacking. Aims of this retrospective, cross-sectional study were to describe and compare standing low-field magnetic resonance findings in the metacarpophalangeal joints for groups of Standardbreds and Thoroughbreds using systematic semiquantitative scores...
May 17, 2017: Veterinary Radiology & Ultrasound
https://www.readbyqxmd.com/read/28516042/sensitivity-enhancement-of-traveling-wave-mri-using-free-local-resonators-an-experimental-demonstration
#19
Xiaoliang Zhang
BACKGROUND: Traveling wave MR uses the far fields in signal excitation and reception, therefore its acquisition efficiency is low in contrast to the conventional near field magnetic resonance (MR). Here we show a simple and efficient method based on the local resonator to improving sensitivity of traveling wave MR technique. The proposed method utilizes a standalone or free local resonator to amplify the radio frequency magnetic fields in the interested target. The resonators have no wire connections to the MR system and thus can be conveniently placed to any place around imaging simples...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28507682/sabre-hyperpolarisation-of-vitamin-b3-as-a-function-of-ph
#20
A M Olaru, M J Burns, G G R Green, S B Duckett
In this work we describe how the signal enhancements obtained through the SABRE process in methanol-d4 solution are significantly affected by pH. Nicotinic acid (vitamin B3, NA) is used as the agent, and changing pH is shown to modify the level of polarisation transfer by over an order of magnitude, with significant improvements being seen in terms of the signal amplitude and relaxation rate at high pH values. These observations reveal that manipulating pH to improve SABRE enhancements levels may improve the potential of this method to quantify low concentrations of analytes in mixtures...
March 1, 2017: Chemical Science
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