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Journal of Magnetic Resonance

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https://www.readbyqxmd.com/read/29778834/generating-para-water-from-para-hydrogen-a-gedankenexperiment
#1
Konstantin L Ivanov, Geoffrey Bodenhausen
A novel conceptual approach is described that is based on the transfer of hyperpolarization from para-hydrogen in view of generating a population imbalance between the two spin isomers of H2 O. The approach is analogous to SABRE (Signal Amplification By Reversible Exchange) and makes use of the transfer of spin order from para-hydrogen to H2 O in a hypothetical organometallic complex. The spin order transfer is expected to be most efficient at avoided level crossings. The highest achievable enrichment levels of para- and ortho-water are discussed...
May 17, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29778072/nmr-at-pressures-up-to-90-gpa
#2
Thomas Meier, Saiana Khandarkhaeva, Sylvain Petitgirard, Thomas Körber, Alexander Lauerer, Ernst Rössler, Leonid Dubrovinsky
The past 15 years have seen an astonishing increase in Nuclear Magnetic Resonance (NMR) sensitivity and accessible pressure range in high-pressure NMR experiments, owing to a series of new developments of NMR spectroscopy applied to the diamond anvil cell (DAC). Recently, with the application of electro-magnetic lenses, so-called Lenz lenses, in toroidal diamond indenter cells, pressures of up to 72 GPa with NMR spin sensitivities of about 1012  spin/Hz1/2 has been achieved. Here, we describe the implementation of a refined NMR resonator structure using a pair of double stage Lenz lenses driven by a Helmholtz coil within a standard DAC, allowing to measure sample volumes as small as 100 pl prior to compression...
May 14, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29763794/design-and-experimental-validation-of-unilateral-linear-halbach-magnet-arrays-for-single-sided-magnetic-resonance
#3
Ashvin Bashyam, Matthew Li, Michael J Cima
Single-sided NMR has the potential for broad utility and has found applications in healthcare, materials analysis, food quality assurance, and the oil and gas industry. These sensors require a remote, strong, uniform magnetic field to perform high sensitivity measurements. We demonstrate a new permanent magnet geometry, the Unilateral Linear Halbach, that combines design principles from "sweet-spot" and linear Halbach magnets to achieve this goal through more efficient use of magnetic flux. We perform sensitivity analysis using numerical simulations to produce a framework for Unilateral Linear Halbach design and assess tradeoffs between design parameters...
May 9, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29751275/computational-approach-to-integrate-3d-x-ray-microtomography-and-nmr-data
#4
Everton Lucas-Oliveira, Arthur G Araujo-Ferreira, Willian A Trevizan, Carlos A Fortulan, Tito J Bonagamba
Nowadays, most of the efforts in NMR applied to porous media are dedicated to studying the molecular fluid dynamics within and among the pores. These analyses have a higher complexity due to morphology and chemical composition of rocks, besides dynamic effects as restricted diffusion, diffusional coupling, and exchange processes. Since the translational nuclear spin diffusion in a confined geometry (e.g. pores and fractures) requires specific boundary conditions, the theoretical solutions are restricted to some special problems and, in many cases, computational methods are required...
May 4, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29751276/measurement-of-short-transverse-relaxation-times-by-pseudo-echo-nutation-experiments
#5
Maude Ferrari, Christian Moyne, Daniel Canet
Very short NMR transverse relaxation times may be difficult to measure by conventional methods. Nutation experiments constitute an alternative approach. Nutation is, in the rotating frame, the equivalent of precession in the laboratory frame. It consists in monitoring the rotation of magnetization around the radio-frequency (rf) field when on-resonance conditions are fulfilled. Depending on the amplitude of the rf field, nutation may be sensitive to the two relaxation rates R1 and R2 . A full theoretical development has been worked out for demonstrating how these two relaxation rates could be deduced from a simple nutation experiment, noticing however that inhomogeneity of the rf field may lead to erroneous results...
May 3, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29758451/diffusion-effect-on-t2-relaxometry-in-triple-echo-steady-state-free-precession-sequence
#6
Yangzi Qiao, Chao Zou, Chuanli Cheng, Qian Wan, Changjun Tie, Dong Liang, Hairong Zheng, Xin Liu, Yiu-Cho Chung
PURPOSE: The purpose of this study is to evaluate the effect of diffusion on SSFP (Steady-state Free Precession) signals in triple-echo steady state (TESS) sequence and ultimately on the accuracy of T2 relaxometry. METHODS: The extended phase graph (EPG) algorithm was used to study the effect of diffusion on SSFP signals and T2 relaxometry. The simulation results were verified by a commercial phantom and in vivo studies. Based on the simulation results, a correction scheme was proposed to correct the estimated T2 values...
May 2, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29773299/diffusion-mri-in-acute-nervous-system-injury
#7
Matthew D Budde, Nathan P Skinner
Diffusion weighted magnetic resonance imaging (DWI) and related techniques such as diffusion tensor imaging (DTI) are uniquely sensitive to the microstructure of the brain and spinal cord. In the acute aftermath of nervous system injury, for example, DWI reveals changes caused by injury that remains invisible on other MRI contrasts such as T2 -weighted imaging. This ability has led to a demonstrated clinical utility in cerebral ischemia. However, despite strong promise in preclinical models and research settings, DWI has not been as readily adopted for other acute injuries such as traumatic spinal cord, brain, or peripheral nerve injury...
April 30, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29731237/recent-advances-in-preclinical-and-clinical-multimodal-mr-in-the-newborn-brain
#8
Vicente Enguix, Yang Ding, Gregory A Lodygensky
Aside from injury identification, MRI of the newborn brain has given us insight into cortical and white matter development, identified windows of vulnerabilities, enabled the introduction of therapeutic hypothermia which has become the standard of care in neonatal asphyxia, and is fostering leapfrogging discoveries in the field of neuro-genetics. This article reviews the main advances in recent years in newborn brain imaging both in preclinical and clinical research.
April 30, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29753980/exploring-methods-to-expedite-the-recording-of-cest-datasets-using-selective-pulse-excitation
#9
Tairan Yuwen, Guillaume Bouvignies, Lewis E Kay
Chemical Exchange Saturation Transfer (CEST) has emerged as a powerful tool for studies of biomolecular conformational exchange involving the interconversion between a major, visible conformer and one or more minor, invisible states. Applications typically entail recording a large number of 2D datasets, each of which differs in the position of a weak radio frequency field, so as to generate a CEST profile for each nucleus from which the chemical shifts of spins in the invisible state(s) are obtained. Here we compare a number of band-selective CEST schemes for speeding up the process using either DANTE or cosine-modulated excitation approaches...
April 26, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29730126/lorentzian-effects-in-magnetic-susceptibility-mapping-of-anisotropic-biological-tissues
#10
Dmitriy A Yablonskiy, Alexander L Sukstanskii
The ultimate goal of MRI is to provide information on biological tissue microstructure and function. Quantitative Susceptibility Mapping (QSM) is one of the newer approaches for studying tissue microstructure by means of measuring phase of Gradient Recalled Echo (GRE) MRI signal. The fundamental question in the heart of this approach is: what is the relationship between the net phase/frequency of the GRE signal from an imaging voxel and the underlying tissue microstructure at the cellular and sub-cellular levels? In the presence of external magnetic field, biological media (e...
April 26, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29716831/in-vivo-mr-in-the-drug-pipeline
#11
Jeffrey L Evelhoch
The application of in vivo magnetic resonance (MR) in drug development has several requirements that differ significantly from most applications primarily because the biopharmaceutical industry must develop new safe and effective drugs more quickly and at lower cost in a highly regulated environment. In vivo MR is recognized as a useful method to provide biomarkers for target engagement, treatment response, safety and mechanism of action that can be translated between animal and clinical studies. Thus, it has the potential to help identify drugs that are more likely to be safe and effective earlier in the process of drug development, which may help reduce the time and money required to get new drugs to patients with an unmet medical need...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705043/using-1-h-2-o-mr-to-measure-and-map-sodium-pump-activity-in-vivo
#12
Charles S Springer
The cell plasma membrane Na+ ,K+ -ATPase [NKA] is one of biology's most [if not the most] significant enzymes. By actively transporting Na+ out [and K+ in], it maintains the vital trans-membrane ion concentration gradients and the membrane potential. The forward NKA reaction is shown in the Graphical Abstract [which is elaborated in the text]. Crucially, NKA does not operate in isolation. There are other transporters that conduct K+ back out of [II, Graphical Abstract] and Na+ back into [III, Graphical Abstract] the cell...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705042/pre-clinical-mr-elastography-principles-techniques-and-applications
#13
P V Bayly, J R Garbow
Magnetic resonance elastography (MRE) is a method for measuring the mechanical properties of soft tissue in vivo, non-invasively, by imaging propagating shear waves in the tissue. The speed and attenuation of waves depends on the elastic and dissipative properties of the underlying material. Tissue mechanical properties are essential for biomechanical models and simulations, and may serve as markers of disease, injury, development, or recovery. MRE is already established as a clinical technique for detecting and characterizing liver disease...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705041/white-matter-biomarkers-from-diffusion-mri
#14
Sune Nørhøj Jespersen
As part of an issue celebrating 2 decades of Joseph Ackerman editing the Journal of Magnetic Resonance, this paper reviews recent progress in one of the many areas in which Ackerman and his lab has made significant contributions: NMR measurement of diffusion in biological media, specifically in brain tissue. NMR diffusion signals display exquisite sensitivity to tissue microstructure, and have the potential to offer quantitative and specific information on the cellular scale orders of magnitude below nominal image resolution when combined with biophysical modeling...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705040/theranostics-and-metabolotheranostics-for-precision-medicine-in-oncology
#15
Zaver M Bhujwalla, Samata Kakkad, Zhihang Chen, Jiefu Jin, Sudath Hapuarachchige, Dmitri Artemov, Marie-France Penet
Most diseases, especially cancer, would significantly benefit from precision medicine where treatment is shaped for the individual. The concept of theragnostics or theranostics emerged around 2002 to describe the incorporation of diagnostic assays into the selection of therapy for this purpose. Increasingly, theranostics has been used for strategies that combine noninvasive imaging-based diagnostics with therapy. Within the past decade theranostic imaging has transformed into a rapidly expanding field that is located at the interface of diagnosis and therapy...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705039/using-diffusion-anisotropy-to-study-cerebral-cortical-gray-matter-development
#16
Christopher D Kroenke
Diffusion-weighted magnetic resonance imaging (diffusion MRI) is being used to characterize morphological development of cells within developing cerebral cortical gray matter. Abnormal morphology is a shared characteristic of cerebral cortical neurons for many neurodevelopmental disorders, and therefore diffusion MRI is potentially of high value for monitoring growth-related anatomical changes of relevance to brain function. Here, the theoretical framework for analyzing diffusion MRI data is summarized. An overview of quantitative methods for validating the interpretations of diffusion MRI data using light microscopy is then presented...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705038/in-vivo-nmr-investigations-of-glyphosate-influences-on-plant-metabolism
#17
D André d'Avignon, Xia Ge
Glyphosate is the world's most widely used herbicide; popular due to its relative low cost, low toxicity, and high efficacy in controlling most common weed species. Genetic engineering of crop seeds to be glyphosate-tolerant has facilitated the modern global agricultural practice whereby both weeds and crops are treated with herbicide, while only the crops survive. However, due to extreme selective pressure, glyphosate-resistant (GR) weed species are now found with increasing frequency in nature, threatening the dominant weed management system used in large-scale agriculture across much of the globe...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705036/oxidative-stress-measured-in-vivo-without-an-exogenous-contrast-agent-using-quest-mri
#18
Bruce A Berkowitz
Decades of experimental studies have implicated excessive generation of reactive oxygen species (ROS) in the decline of tissue function during normal aging, and as a pathogenic factor in a vast array of fatal or debilitating morbidities. This massive body of work has important clinical implications since many antioxidants are FDA approved, readily cross blood-tissue barriers, and are effective at improving disease outcomes. Yet, the potential benefits of antioxidants have remained largely unrealized in patients because conventional methods cannot determine the dose, timing, and drug combinations to be used in clinical trials to localize and decrease oxidative stress...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705035/rf-pulse-methods-for-use-with-surface-coils-frequency-modulated-pulses-and-parallel-transmission
#19
Michael Garwood, Kamil Uğurbil
The first use of a surface coil to obtain a 31 P NMR spectrum from an intact rat by Ackerman and colleagues initiated a revolution in magnetic resonance imaging (MRI) and spectroscopy (MRS). Today, we take it for granted that one can detect signals in regions external to an RF coil; at the time, however, this concept was most unusual. In the approximately four decade long period since its introduction, this simple idea gave birth to an increasing number of innovations that has led to transformative changes in the way we collect data in an in vivo magnetic resonance experiment, particularly with MRI of humans...
April 25, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29705034/preclinical-mri-studies-of-the-irradiated-brain
#20
Joel R Garbow, Christina I Tsien, Scott C Beeman
Radiation therapy (RT) plays a central role in the treatment of primary brain tumors. However, despite recent advances in RT treatment, local recurrences following therapy remain common. Radiation necrosis (RN) is a severe, late complication of radiation therapy in the brain. RN is a serious clinical problem often associated with devastating neurologic complications. Therapeutic strategies, including neuroprotectants, have been described, but have not been widely translated in routine clinical use. We have developed a mouse model that recapitulates all of the major pathologic features of late-onset RN for the purposes of characterizing the basic pathogenesis of RN, identifying non-invasive (imaging) biomarkers of RN that might allow for the radiologic discernment of tumor and RN, systematic testing of tumor and RN therapeutics, and exploring the complex interplay between RN pathogenesis and tumor recurrence...
April 25, 2018: Journal of Magnetic Resonance
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