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https://www.readbyqxmd.com/read/28639301/improving-the-detection-sensitivity-of-ph-weighted-amide-proton-transfer-mri-in-acute-stroke-patients-using-extrapolated-semisolid-magnetization-transfer-reference-signals
#1
Hye-Young Heo, Yi Zhang, Tina M Burton, Shanshan Jiang, Yansong Zhao, Peter C M van Zijl, Richard Leigh, Jinyuan Zhou
PURPOSE: To quantify amide protein transfer (APT) effects in acidic ischemic lesions and assess the spatial-temporal relationship among diffusion, perfusion, and pH deficits in acute stroke patients. METHODS: Thirty acute stroke patients were scanned at 3 T. Quantitative APT (APT(#) ) effects in acidic ischemic lesions were measured using an extrapolated semisolid magnetization transfer reference signal technique and compared with commonly used MTRasym (3.5ppm) or APT-weighted parameters...
June 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28601503/cortical-magnetization-transfer-abnormalities-and-connectome-dysconnectivity-in-schizophrenia
#2
Yongbin Wei, Guusje Collin, René C W Mandl, Wiepke Cahn, Kristin Keunen, Ruben Schmidt, René S Kahn, Martijn P van den Heuvel
Macroscale dysconnectivity in schizophrenia is associated with neuropathological abnormalities. The extent to which alterations in cortical myelination as revealed in vivo by magnetization transfer ratio (MTR) are related to macroscale dysconnectivity remains unknown. We acquired magnetization transfer imaging (MTI) data and diffusion weighted imaging (DWI) data from 78 schizophrenia patients and 93 healthy controls for MTR extraction and connectome reconstruction to examine the possible link between cortical myelination and macroscale dysconnectivity...
June 7, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/28595121/magnetization-transfer-in-a-partly-deuterated-lyotropic-liquid-crystal-by-single-and-dual-frequency-rf-irradiations
#3
Jae-Seung Lee, Ravinder R Regatte, Alexej Jerschow
The mechanism of magnetization transfer (MT) in a lyotropic liquid crystal made of sodium dodecyl sulfate, decanol, and water molecules is investigated by using deuterated molecules and single- and dual-frequency RF irradiations. The resulting Z-spectra suggest that the decanol molecules are mainly responsible for the MT effects in this system, through proton exchange to water. This is further confirmed by monitoring the relaxation of dipolar order, which allows one to estimate the transfer rate of magnetization from decanol to water...
May 31, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28586096/spinal-cord-multi-parametric-magnetic-resonance-imaging-for-survival-prediction-in-amyotrophic-lateral-sclerosis
#4
G Querin, M M El Mendili, T Lenglet, S Delphine, V Marchand-Pauvert, H Benali, P-F Pradat
BACKGROUND AND PURPOSE: Assessing survival is a critical issue in patients with amyotrophic lateral sclerosis (ALS). Neuroimaging seems to be promising in the assessment of disease severity and several studies also suggest a strong relationship between spinal cord (SC) atrophy described by magnetic resonance imaging (MRI) and disease progression. The aim of the study was to determine the predictive added value of multimodal SC MRI on survival. METHODS: Forty-nine ALS patients were recruited and clinical data were collected...
June 6, 2017: European Journal of Neurology: the Official Journal of the European Federation of Neurological Societies
https://www.readbyqxmd.com/read/28583638/a-phase-i-clinical-trial-of-the-knee-to-assess-the-correlation-of-gagcest-mri-delayed-gadolinium-enhanced-mri-of-cartilage-and-t2-mapping
#5
Wenbo Wei, Becky Lambach, Guang Jia, Christopher Kaeding, David Flanigan, Michael V Knopp
PURPOSE: Osteoarthritis (OA) is associated with the loss of glycosaminoglycan (GAG) during disease progression, which can be detected by glycosaminoglycan chemical exchange-dependent saturation transfer (gagCEST) MRI. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is considered one of the standard methods for GAG quantification in vivo. This Phase I study assessed the correlation between gagCEST MRI and dGEMRIC in determining cartilage GAG concentration. Standard T2 mapping was used as a comparator with the two other methods...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28579146/myelin-breakdown-in-human-huntington-s-disease-multi-modal-evidence-from-diffusion-mri-and-quantitative-magnetization-transfer
#6
José Bourbon-Teles, Sonya Bells, Derek K Jones, Elizabeth Coulthard, Anne Rosser, Claudia Metzler-Baddeley
Huntington's disease (HD) leads to white matter (WM) degeneration that may be due to an early breakdown in axon myelination but in vivo imaging correlates of demyelination remain relatively unexplored in HD compared to other neurodegenerative diseases. This study investigated HD-related effects on a putative marker of myelin, the macromolecular proton fraction (MMPF) from quantitative magnetization transfer and on fractional anisotropy, axial and radial diffusivity from diffusion tensor MR-imaging. Microstructural differences were studied in WM pathways of the basal ganglia and motor systems known to be impaired in HD: the corpus callosum, the cortico-spinal tract, the anterior thalamic radiation, fibers between prefrontal cortex and caudate and between supplementary motor area and putamen...
June 1, 2017: Neuroscience
https://www.readbyqxmd.com/read/28575122/multimodal-assessment-of-white-matter-tracts-in-amyotrophic-lateral-sclerosis
#7
Florian Borsodi, Valeriu Culea, Christian Langkammer, Michael Khalil, Lukas Pirpamer, Stefan Quasthoff, Christian Enzinger, Reinhold Schmidt, Franz Fazekas, Stefan Ropele
Several quantitative magnetic resonance imaging (MRI) techniques have been proposed to investigate microstructural tissue changes in amyotrophic lateral sclerosis (ALS) including diffusion tensor imaging (DTI), magnetization transfer imaging, and R2* mapping. Here, in this study, we compared these techniques with regard to their capability for detecting ALS related white matter (WM) changes in the brain and their association with clinical findings. We examined 27 ALS patients and 35 age-matched healthy controls...
2017: PloS One
https://www.readbyqxmd.com/read/28567261/amplifying-undetectable-nmr-signals-to-study-host-guest-interactions-and-exchange
#8
Liat Avram, Mark A Iron, Amnon Bar-Shir
The characteristics of host-guest systems, such as molecular recognition, complexation, encapsulation, guest composition, and dynamic exchange, are manifested by changes in the chemical shifts (Δω) in the NMR spectrum. However, in cases where NMR signals cannot be detected, due to low concentrations, poor solubility, or relatively fast exchange, an alternative is needed. Here, we show that by using the magnetization transfer (MT) method, the undetectable NMR signals of host-guest assemblies can be amplified by two orders of magnitude...
December 1, 2016: Chemical Science
https://www.readbyqxmd.com/read/28566586/b1-power-optimization-for-chemical-exchange-saturation-transfer-imaging-a-phantom-study-using-egg-white-for-amide-proton-transfer-imaging-applications-in-the-human-brain
#9
Yuki Kanazawa, Yasutaka Fushimi, Naotaka Sakashita, Tomohisa Okada, Yoshiki Arakawa, Mitsue Miyazaki
The chemical exchange saturation transfer (CEST) effect on an egg white (EW) suspension was investigated for optimization of magnetization transfer (MT) power (B1,rms) and pH dependency with the addition of lactic acid. Applying a higher MT pulse, B1,rms, Z-spectrum shows higher asymmetry and the magnetisation transfer ratio (MTR)asym signal increases to around 1-3.5 ppm, indicating a higher CEST effect. Amide proton transfer (APT) at 3.5 ppm shows a signal elevation in MTRasym with the application of higher B1,rms power and high pH...
May 31, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28547862/mri-evaluation-of-regional-and-longitudinal-changes-in-z-spectra-of-injured-spinal-cord-of-monkeys
#10
Feng Wang, Zhongliang Zu, Ruiqi Wu, Tung-Lin Wu, John C Gore, Li Min Chen
PURPOSE: In principle, MR methods that exploit magnetization transfer (MT) may be used to quantify changes in the molecular composition of tissues after injury. The ability to track such changes in injured spinal cord may allow more precise assessment of the state of neural tissues. METHODS: Z-Spectra were obtained from the cervical spinal cord before and after a unilateral dorsal column lesion in monkeys at 9.4T. The amplitudes of chemical exchange saturation transfer (CEST) and nuclear Overhauser enhancement (NOE) effects from multiple proton pools, along with nonspecific semisolid MT effects from immobile macromolecules, were quantified using a five-peak Lorenzian fitting of each Z-spectrum...
May 25, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28543840/imaging-of-nuclear-overhauser-enhancement-at-7-and-3%C3%A2-t
#11
Yuanyu Shen, Gang Xiao, Zhiwei Shen, Xiaolei Zhang, Xiangyong Tang, Wei Hu, Zhiyan Zhang, Jitian Guan, Renhua Wu
Nuclear Overhauser enhancement (NOE) is a type of magnetization transfer using cross-relaxation. It originates from mobile macromolecules, which may have relevance to the evaluation of tumor features. We studied the value of NOE imaging at 7 and 3 T and suggest a utility for diagnosing human brain tumors. Two types of protein solution at different concentrations and pH values, and six normal Sprague Dawley (SD) rats, were used to detect NOE signal with a 7 T scanner. Then, six healthy volunteers and 11 patients with brain tumors (six gliomas and five meningiomas) were included at 3 T...
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28542095/magnetization-transfer-magnetic-resonance-imaging-noninvasively-detects-renal-fibrosis-in-swine-atherosclerotic-renal-artery-stenosis-at-3-0-t
#12
Kai Jiang, Christopher M Ferguson, John R Woollard, Xiangyang Zhu, Lilach O Lerman
OBJECTIVES: Renal fibrosis is a useful biomarker for diagnosis and evaluation of therapeutic interventions of renal diseases but often requires invasive testing. Magnetization transfer magnetic resonance imaging (MT-MRI), which evaluates the presence of macromolecules, offers a noninvasive tool to probe renal fibrosis in murine renal artery stenosis (RAS) at 16.4 T. In this study, we aimed to identify appropriate imaging parameters for collagen detection at 3.0 T MRI and to test the utility of MT-MRI in measuring renal fibrosis in a swine model of atherosclerotic RAS (ARAS)...
May 24, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/28527566/abnormalities-in-high-energy-phosphate-metabolism-in-first-episode-bipolar-disorder-measured-using-31-p-magnetic-resonance-spectroscopy
#13
Fei Du, Cagri Yuksel, Virginie-Anne Chouinard, Polly Huynh, Kyle Ryan, Bruce M Cohen, Dost Öngür
BACKGROUND: Brain energy metabolism is critical for supporting synaptic function and information processing. A growing body of evidence suggests abnormalities in brain bioenergetics in psychiatric disorders, including both bipolar disorder (BD) and schizophrenia. (31)P magnetic resonance spectroscopy provides a noninvasive window into these processes in vivo. Using this approach, we previously showed that patients with BD show normal adenosine triphosphate (ATP) and phosphocreatine levels at rest but cannot maintain normal ATP levels in the visual cortex during times of high energy demand (photic stimulation)...
April 7, 2017: Biological Psychiatry
https://www.readbyqxmd.com/read/28526431/measurement-of-apt-using-a-combined-cert-arex-approach-with-varying-duty-cycles
#14
Zhongliang Zu, Hua Li, Junzhong Xu, Xiao-Yong Zhang, Moritz Zaiss, Ke Li, Mark D Does, John C Gore, Daniel F Gochberg
The goal is to develop an imaging method where contrast reflects amide-water magnetization exchange, with minimal signal contributions from other sources. Conventional chemical exchange saturation transfer (CEST) imaging of amides (often called amide proton transfer, or APT, and quantified by the metric MTRasym) is confounded by several factors unrelated to amides, such as aliphatic protons, water relaxation, and macromolecular magnetization transfer. In this work, we examined the effects of combining our previous chemical exchange rotation (CERT) approach with the non-linear AREX method while using different duty cycles (DC) for the label and reference scans...
May 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28522663/the-use-of-noncontrast-quantitative-mri-to-detect-gadolinium-enhancing-multiple-sclerosis-brain-lesions-a-systematic-review-and-meta-analysis
#15
A Gupta, K Al-Dasuqi, F Xia, G Askin, Y Zhao, D Delgado, Y Wang
BACKGROUND: Concerns have arisen about the long-term health effects of repeat gadolinium injections in patients with multiple sclerosis and the incomplete characterization of MS lesion pathophysiology that results from relying on enhancement characteristics alone. PURPOSE: Our aim was to perform a systematic review and meta-analysis analyzing whether noncontrast MR imaging biomarkers can distinguish enhancing and nonenhancing brain MS lesions. DATA SOURCES: Our sources were Ovid MEDLINE, Ovid Embase, and the Cochrane data base from inception to August 2016...
May 18, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28510013/nmr-magnetization-transfer-analysis-of-rapid-membrane-transport-in-human-erythrocytes
#16
REVIEW
Dmitry Shishmarev, Philip W Kuchel
Nuclear magnetic resonance (NMR) magnetization-transfer (MT) experiments provide a convenient tool for studying rapid sub-second membrane-transport processes in situ in metabolically active cells. These experiments are used with membrane-permeable substances when separate (resolved) NMR signals are observed from their populations inside and outside the cells. Here, we provide a description of the theory and practice of the most common NMR MT experiments that have been used to study membrane-transport processes in human erythrocytes (red blood cells; RBCs)...
December 2016: Biophysical Reviews
https://www.readbyqxmd.com/read/28482644/olfactory-impairment-in-parkinson-s-disease-studied-with-diffusion-tensor-and%C3%A2-magnetization-transfer-imaging
#17
Charalampos Georgiopoulos, Marcel Warntjes, Nil Dizdar, Helene Zachrisson, Maria Engström, Sven Haller, Elna-Marie Larsson
BACKGROUND: Olfactory impairment is an early manifestation of Parkinson's disease (PD). Diffusion Tensor Imaging (DTI) and Magnetization Transfer (MT) are two imaging techniques that allow noninvasive detection of microstructural changes in the cerebral white matter. OBJECTIVE: To assess white matter alterations associated with olfactory impairment in PD, using a binary imaging approach with DTI and MT. METHODS: 22 PD patients and 13 healthy controls were examined with DTI, MT and an odor discrimination test...
2017: Journal of Parkinson's Disease
https://www.readbyqxmd.com/read/28477231/comparison-of-the-free-and-ligand-bound-imino-hydrogen-exchange-rates-for-the-cocaine-binding-aptamer
#18
Zachary R Churcher, Miguel A D Neves, Howard N Hunter, Philip E Johnson
Using NMR magnetization transfer experiments, the hydrogen exchange rate constants (k ex ) of the DNA imino protons in the cocaine-binding aptamer have been determined for the free, cocaine-bound, and quinine-bound states. The secondary structure of the cocaine-binding aptamer is composed of three stems built around a three-way junction. In the free aptamer the slowest exchanging imino protons are located in the middle of the stems. The highest k ex values were found for a nucleotide in the GAA loop of stem 3 and for nucleotides at the end of the stems that form the three-way junction structure and in the tandem GA mismatch...
May 5, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28474409/amide-proton-transfer-cest-of-the-cervical-spinal-cord-in-multiple-sclerosis-patients-at-3t
#19
Samantha By, Robert L Barry, Alex K Smith, Bailey D Lyttle, Bailey A Box, Francesca R Bagnato, Siddharama Pawate, Seth A Smith
PURPOSE: The ability to evaluate pathological changes in the spinal cord in multiple sclerosis (MS) is limited because T1 - and T2 -w MRI imaging are not sensitive to biochemical changes in vivo. Amide proton transfer (APT) chemical exchange saturation transfer (CEST) can indirectly detect amide protons associated with proteins and peptides, potentially providing more pathological specificity. Here, we implement APT CEST in the cervical spinal cord of healthy and MS cohorts at 3T. METHODS: APT CEST of the cervical spinal cord was obtained in a cohort of 10 controls and 10 MS patients using a novel respiratory correction methodology...
May 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28470838/quantitative-magnetization-transfer-ultrashort-echo-time-imaging-using-a-time-efficient-3d-multispoke-cones-sequence
#20
Ya-Jun Ma, Eric Y Chang, Michael Carl, Jiang Du
PURPOSE: To accelerate the quantitative ultrashort echo time imaging using a time-efficient 3D multispoke Cones sequence with magnetization transfer (3D UTE-Cones-MT) and signal modeling. THEORY AND METHODS: A 3D UTE-Cones-MT acquisition scheme with multispoke per MT preparation and a modified rectangular pulse (RP) approximation was developed for two-pool MT modeling of macromolecular and water components including their relative fractions, relaxation times and exchange rates...
May 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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