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"magnetization transfer"

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https://www.readbyqxmd.com/read/28226699/estimating-multimodal-brain-connectivity-in-multiple-sclerosis-an-exploratory-factor-analysis
#1
Matteo Mancini, Giovanni Giulietti, Barbara Spano, Marco Bozzali, Mara Cercignani, Silvia Conforto, Matteo Mancini, Giovanni Giulietti, Barbara Spano, Marco Bozzali, Mara Cercignani, Silvia Conforto, Giovanni Giulietti, Mara Cercignani, Silvia Conforto, Matteo Mancini, Barbara Spano, Marco Bozzali
Graph-theoretical approaches have become a popular way to model brain data collected using magnetic resonance imaging (MRI), both from the structural and the functional perspectives. In structural networks, tract-based mapping allows to model different aspects of brain structures by means of the specific characteristics of the different MRI modalities. However, there has been little effort to join the information carried by each modality and to understand what level of common variance is shown in these data...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28212272/design-of-novel-fbg-based-sensor-of-differential-pressure-with-magnetic-transfer
#2
Guohui Lyu, Guohang Che, Junqing Li, Xu Jiang, Keda Wang, Yueqiang Han, Laixu Gao
In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements...
February 15, 2017: Sensors
https://www.readbyqxmd.com/read/28195663/optimization-of-inhomogeneous-magnetization-transfer-ihmt-mri-contrast-for-preclinical-studies-using-dipolar-relaxation-time-t1d-filtering
#3
V H Prevost, O M Girard, S Mchinda, G Varma, D C Alsop, G Duhamel
A pulsed inhomogeneous magnetization transfer (ihMT)-prepared fast imaging sequence was implemented at 11.75 T for preclinical studies on mouse central nervous system. A strategy based on filtering the ihMT signal originating from short dipolar relaxation time (T1D ) components is proposed. It involves increasing the repetition time of consecutive radiofrequency (RF) pulses of the dual saturation and allows improved signal specificity for long T1D myelinated structures. Furthermore, frequency offset, power and timing saturation parameters were adjusted to optimize the ihMT sensitivity...
February 14, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28183276/peginterferon-beta-1a-improves-mri-measures-and-increases-the-proportion-of-patients-with-no-evidence-of-disease-activity-in-relapsing-remitting-multiple-sclerosis-2-year-results-from-the-advance-randomized-controlled-trial
#4
Douglas L Arnold, Peter A Calabresi, Bernd C Kieseier, Shifang Liu, Xiaojun You, Damian Fiore, Serena Hung
BACKGROUND: Subcutaneous peginterferon beta-1a has previously been shown to reduce the number of T2-hyperintense and gadolinium-enhancing (Gd+) lesions over 2 years in patients with relapsing-remitting multiple sclerosis (RRMS), and to reduce T1-hypointense lesion formation and the proportion of patients showing evidence of disease activity, based on both clinical and radiological measures, compared with placebo over 1 year of treatment. The objectives of the current analyses were to evaluate T1 lesions and other magnetic resonance imaging (MRI) measures, including whole brain volume and magnetization transfer ratio (MTR) of normal appearing brain tissue (NABT), and the proportions of patients with no evidence of disease activity (NEDA), over 2 years...
February 10, 2017: BMC Neurology
https://www.readbyqxmd.com/read/28174533/reward-dependent-invigoration-relates-to-theta-oscillations-and-is-predicted-by-dopaminergic-midbrain-integrity-in-healthy-elderly
#5
Tineke K Steiger, Nico Bunzeck
Motivation can have invigorating effects on behavior via dopaminergic neuromodulation. While this relationship has mainly been established in theoretical models and studies in younger subjects, the impact of structural declines of the dopaminergic system during healthy aging remains unclear. To investigate this issue, we used electroencephalography (EEG) in healthy young and elderly humans in a reward-learning paradigm. Specifically, scene images were initially encoded by combining them with cues predicting monetary reward (high vs...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/28150877/spectral-characteristics-of-semisolid-protons-in-human-brain-white-matter-at-7-t
#6
Xu Jiang, Peter van Gelderen, Jeff H Duyn
PURPOSE: To inform the quantification of MRI magnetization transfer contrast at high field by measuring the spectral characteristics of (1) H protons in semisolids in human brain at 7 T, while avoiding prohibitive radiofrequency (RF) tissue heating and confounding effects from chemical exchange. METHODS: Saturation-recovery type experiments were performed using brief, frequency-specific RF pulses that saturate semisolid proton magnetization. Analysis of the subsequent recovery of water proton magnetization with a two-pool model of exchange allowed the study of spectral characteristics of semisolid protons...
February 2, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28147365/measurement-of-fibrosis-in-crohn-s-disease-strictures-with-imaging-and-blood-biomarkers-to-inform-clinical-decisions
#7
REVIEW
Peter D R Higgins
BACKGROUND: Distinguishing fibrosis from inflammation in an intestinal stricture in Crohn's disease is quite difficult. The absence of signs of inflammation on CT or MRI does not prove the absence of inflammation, as most strictures have a mix of fibrosis and inflammation. Identifying refractory fibrosis and distinguishing the patients who will respond to anti-inflammatory therapy from those who will require surgery are important clinical requirements, and several new technologies in imaging and serum biomarkers are being applied to this problem...
2017: Digestive Diseases
https://www.readbyqxmd.com/read/28131894/gaba-and-glutamate-levels-correlate-with-mtr-and-clinical-disability-insights-from-multiple-sclerosis
#8
Julia C Nantes, Sébastien Proulx, Jidan Zhong, Scott A Holmes, Sridar Narayanan, Robert A Brown, Richard D Hoge, Lisa Koski
Converging areas of research have implicated glutamate and γ-aminobutyric acid (GABA) as key players in neuronal signalling and other central functions. Further research is needed, however, to identify microstructural and behavioral links to regional variability in levels of these neurometabolites, particularly in the presence of demyelinating disease. Thus, we sought to investigate the extent to which regional glutamate and GABA levels are related to a neuroimaging marker of microstructural damage and to motor and cognitive performance...
January 25, 2017: NeuroImage
https://www.readbyqxmd.com/read/28119180/teriparatide-attenuates-scarring-around-murine-cranial-bone-allograft-via-modulation-of-angiogenesis
#9
Doron Cohn Yakubovich, Uzi Eliav, Eran Yalon, Yeshai Schary, Dmitriy Sheyn, Galen Cook-Wiens, Shuting Sun, Charles E McKenna, Shaya Lev, Alexander M Binshtok, Gadi Pelled, Gil Navon, Dan Gazit, Zulma Gazit
Nearly all bone fractures in humans can deteriorate into a non-union fracture, often due to formation of fibrotic tissue. Cranial allogeneic bone grafts present a striking example: although seemingly attractive for craniofacial reconstructions, they often fail due to fibrosis at the host-graft junction, which physically prevents the desired bridging of bone between the host and graft and revitalization of the latter. In the present study we show that intermittent treatment with recombinant parathyroid hormone-analogue (teriparatide) modulates neovascularization feeding in the graft surroundings, consequently reducing fibrosis and scar tissue formation and facilitates osteogenesis...
January 21, 2017: Bone
https://www.readbyqxmd.com/read/28096269/differentiation-between-radiation-necrosis-and-tumor-progression-using-chemical-exchange-saturation-transfer
#10
Hatef Mehrabian, Kimberly L Desmond, Hany Soliman, Arjun Sahgal, Gregory J Stanisz
PURPOSE: Stereotactic radiosurgery (SRS) is a common treatment used in patients with brain metastases and is associated with high rates of local control, however, at the risk of radiation necrosis. It is difficult to differentiate radiation necrosis from tumor progression using conventional MRI making it a major diagnostic dilemma for practitioners. This prospective study investigated whether chemical exchange saturation transfer (CEST) was able to differentiate these two conditions. MATERIALS & METHODS: Sixteen patients with brain metastases who had been previously treated with SRS were included...
January 17, 2017: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
https://www.readbyqxmd.com/read/28090588/quantitative-magnetization-transfer-imaging-of-the-breast-at-3-0-t-reproducibility-in-healthy-volunteers
#11
Lori R Arlinghaus, Richard D Dortch, Jennifer G Whisenant, Hakmook Kang, Richard G Abramson, Thomas E Yankeelov
Quantitative magnetization transfer magnetic resonance imaging provides a means for indirectly detecting changes in the macromolecular content of tissue noninvasively. A potential application is the diagnosis and assessment of treatment response in breast cancer; however, before quantitative magnetization transfer imaging can be reliably used in such settings, the technique's reproducibility in healthy breast tissue must be established. Thus, this study aims to establish the reproducibility of the measurement of the macromolecular-to-free water proton pool size ratio (PSR) in healthy fibroglandular (FG) breast tissue...
December 2016: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28060254/quantitative-magnetic-resonance-imaging-of-skeletal-muscle-disease
#12
Bruce M Damon, Ke Li, Richard D Dortch, E Brian Welch, Jane H Park, Amanda K W Buck, Theodore F Towse, Mark D Does, Daniel F Gochberg, Nathan D Bryant
Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization...
December 18, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28043954/an-abnormal-periventricular-magnetization-transfer-ratio-gradient-occurs-early-in-multiple-sclerosis
#13
J William L Brown, Matteo Pardini, Wallace J Brownlee, Kryshani Fernando, Rebecca S Samson, Ferran Prados Carrasco, Sebastien Ourselin, Claudia A M Gandini Wheeler-Kingshott, David H Miller, Declan T Chard
In established multiple sclerosis, tissue abnormality-as assessed using magnetization transfer ratio-increases close to the lateral ventricles. We aimed to determine whether or not (i) these changes are present from the earliest clinical stages of multiple sclerosis; (ii) they occur independent of white matter lesions; and (iii) they are associated with subsequent conversion to clinically definite multiple sclerosis and disability. Seventy-one subjects had MRI scanning a median of 4.6 months after a clinically isolated optic neuritis (49 females, mean age 33...
February 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28035783/separating-dipolar-and-chemical-exchange-magnetization-transfer-processes-in-1-h-cest
#14
Tairan Yuwen, Ashok Sekhar, Lewis E Kay
An amide (1) H-Chemical Exchange Saturation Transfer (CEST) experiment is presented for studies of conformational exchange in proteins. The approach, exploiting spin-state-selective magnetization transfer, completely suppresses undesired NOE-based dips in CEST profiles so that chemical exchange processes can be studied. The methodology is demonstrated with applications involving proteins that interconvert on the millisecond timescale between major and invisible minor states, and accurate amide (1) H chemical shifts of the minor conformer are obtained in each case...
December 30, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/28025129/myelin-volume-fraction-imaging-with-mri
#15
Kathryn L West, Nathaniel D Kelm, Robert P Carson, Daniel F Gochberg, Kevin C Ess, Mark D Does
MRI is a valuable tool to assess myelin during development and demyelinating disease processes. While multiexponential T2 and quantitative magnetization transfer measures correlate with myelin content, neither provides the total myelin volume fraction. In many cases correlative measures are adequate; but to assess microstructure of myelin, (e.g. calculate the g-ratio using MRI), an accurate measure of myelin volume fraction is imperative. Using a volumetric model of white matter, we relate MRI measures of myelin to absolute measures of myelin volume fraction and compare them to quantitative histology...
December 23, 2016: NeuroImage
https://www.readbyqxmd.com/read/28019018/contrast-mechanisms-associated-with-neuromelanin-mri
#16
Paula Trujillo, Paul E Summers, Emanuele Ferrari, Fabio A Zucca, Michela Sturini, Luca T Mainardi, Sergio Cerutti, Alex K Smith, Seth A Smith, Luigi Zecca, Antonella Costa
PURPOSE: To investigate the physical mechanisms associated with the contrast observed in neuromelanin MRI. METHODS: Phantoms having different concentrations of synthetic melanins with different degrees of iron loading were examined on a 3 Tesla scanner using relaxometry and quantitative magnetization transfer (MT). RESULTS: Concentration-dependent T1 and T2 shortening was most pronounced for the melanin pigment when combined with iron. Metal-free melanin had a negligible effect on the magnetization transfer spectra...
December 26, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28018953/high-resolution-three-dimensional-quantitative-map-of-the-macromolecular-proton-fraction-distribution-in-the-normal-rat-brain
#17
Anna V Naumova, Andrey E Akulov, Marina Yu Khodanovich, Vasily L Yarnykh
The presented dataset provides a normative high-resolution three-dimensional (3D) macromolecular proton fraction (MPF) map of the healthy rat brain in vivo and source images used for its reconstruction. The images were acquired using the protocol described elsewhere (Naumova, et al. High-resolution three-dimensional macromolecular proton fraction mapping for quantitative neuroanatomical imaging of the rodent brain in ultra-high magnetic fields. Neuroimage (2016) doi: 10.1016/j.neuroimage.2016.09.036). The map was reconstructed from three source images with different contrast weightings (proton density, T1, and magnetization transfer) using the single-point algorithm with a synthetic reference image...
February 2017: Data in Brief
https://www.readbyqxmd.com/read/27988876/edaravone-reduces-astrogliosis-and-apoptosis-in-young-rats-with-kaolin-induced-hydrocephalus
#18
Camila Araújo Bernardino Garcia, Carlos Henrique Rocha Catalão, Hélio Rubens Machado, Ivair Matias Júnior, Thais Helena Romeiro, José Eduardo Peixoto-Santos, Marcelo Volpon Santos, Luiza da Silva Lopes
PURPOSE: We investigated the possible neuroprotective effects of the free radical scavenger edaravone in experimental hydrocephalus. METHODS: Seven-day-old Wistar rats were divided into three groups: control group (C), untreated hydrocephalic (H), and hydrocephalic treated with edaravone (EH). The H and EH groups were subjected to hydrocephalus induction by 20% kaolin intracisternal injection. The edaravone (20 mg/kg) was administered daily for 14 days from the induction of hydrocephalus...
December 17, 2016: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27982487/magnetization-transfer-swift-mri-consistently-detects-histologically-verified-myelin-loss-in-the-thalamocortical-pathway-after-a-traumatic-brain-injury-in-rat
#19
Lauri Juhani Lehto, Alejandra Sierra, Olli Gröhn
Traumatic brain injury (TBI) is associated with various neurocognitive deficits, and rapid assessment of the damage is potentially important for the prevention and treatment of these deficits. Imaging assessment of mild or moderate damage outside the primary lesion area after TBI, however, remains challenging. Magnetization transfer (MT) has clearly been underutilized in imaging the damage caused by TBI. Here, we applied the MT ratio (MTR) using sweep imaging with Fourier transformation (SWIFT) to study microstructural tissue damage in the thalamocortical pathway outside the primary lesion in a lateral fluid percussion injury rat model of TBI, 5 months after injury...
December 16, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27979793/lower-magnetization-transfer-ratio-in-the-forceps-minor-is-associated-with-poorer-gait-velocity-in-older-adults
#20
S Seiler, L Pirpamer, B Gesierich, E Hofer, M Duering, D Pinter, E Jouvent, F Fazekas, J-F Mangin, H Chabriat, S Ropele, R Schmidt
BACKGROUND AND PURPOSE: Gait disturbances in the elderly are disabling and a major public health issue but are poorly understood. In this multimodal MR imaging study, we used 2 voxel-based analysis methods to assess the voxelwise relationship of magnetization transfer ratio and white matter hyperintensity location with gait velocity in older adults. MATERIALS AND METHODS: We assessed 230 community-dwelling participants of the Austrian Stroke Prevention Family Study...
December 15, 2016: AJNR. American Journal of Neuroradiology
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