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Relaxometry

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https://www.readbyqxmd.com/read/29151210/determination-of-protein-ps-ns-motions-by-high-resolution-relaxometry
#1
Samuel F Cousin, Pavel Kadeřávek, Nicolas Bolik-Coulon, Fabien Ferrage
Many of the functions of biomacromolecules can be rationalized by the characterization of their conformational energy landscapes: the structures of the dominant states, transitions between states and motions within states. Nuclear magnetic resonance (NMR) spectroscopy is the technique of choice to study internal motions in proteins. The determination of motions on picosecond to nanosecond timescales requires the measurement of nuclear spin relaxation rates at multiple magnetic fields. High sensitivity and resolution are obtained only at high magnetic fields, so that, until recently, site-specific relaxation rates in biomolecules were only measured over a narrow range of high magnetic fields...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29136287/quantification-of-mri-visibility-and-artefacts-at-3t-of-liquid-fiducial-marker-in-a-pancreas-tissue-mimicking-phantom
#2
Sergej Schneider, Rasmus Irming Jølck, Esther Gera Cornelia Troost, Aswin Louis Hoffmann
PURPOSE: X-ray based position verification of the target volume in image-guided radiation therapy (IGRT) of patients with pancreatic ductal adenocarcinoma (PDAC) is currently performed on solid fiducial markers that are implanted under endoscopic ultrasonography. A new biodegradable liquid fiducial marker has recently been introduced. To assess its potential use for magnetic resonance imaging (MRI) guided photon or proton radiotherapy of PDAC, the MRI visibility and artefacts of this marker were quantified and compared against solid gold markers...
November 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/29120023/role-of-liver-magnetic-resonance-imaging-in-hyperferritinaemia-and-the-diagnosis-of-iron-overload
#3
Axel Ruefer, Christine Bapst, Rudolf Benz, Jens Bremerich, Nathan Cantoni, Laura Infanti, Kaveh Samii, Mathias Schmid, Jean-Paul Vallée
Hyperferritinaemia is a frequent clinical problem. Elevated serum ferritin levels can be detected in different genetic and acquired diseases and can occur with or without anaemia. It is therefore important to determine whether hyperferritinaemia is due to iron overload or due to a secondary cause. The main causes of iron overload are intestinal iron hyperabsorption disorders and transfusion-dependent disorders. Iron homeostasis and iron overload are quantified by different diagnostic approaches. The evaluation of serum ferritin and transferrin saturation is the first diagnostic step to identify the cause of hyperferritinaemia...
November 9, 2017: Swiss Medical Weekly
https://www.readbyqxmd.com/read/29111022/association-of-freezing-of-gait-with-nigral-iron-accumulation-in-patients-with-parkinson-s-disease
#4
Rajini M Naduthota, Arush Arun Honnedevasthana, Abhishek Lenka, Jitender Saini, Sairam Geethanath, Rose Dawn Bharath, Rita Christopher, Ravi Yadav, Arun Kumar Gupta, Pramod Kumar Pal
BACKGROUND AND PURPOSE: The objective of this work was to investigate whether patients with and without freezing of gait (FOG) in Parkinson's disease (PD) have differences in iron accumulation in substantia nigra using R2* relaxometry. MATERIALS AND METHODS: This study included seventeen PD patients with FOG [FOG (+)], equal number of age and gender matched patients without FOG [FOG (-)] and 34 healthy controls (HC). T2* images were obtained from a 3-Tesla MRI system using multi-echo sequence...
November 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/29096054/comparison-of-ferumoxytol-based-cerebral-blood-volume-estimates-using-quantitative-r1-and-r2-relaxometry
#5
Leonardo A Rivera-Rivera, Tilman Schubert, Gesine Knobloch, Patrick A Turski, Oliver Wieben, Scott B Reeder, Kevin M Johnson
PURPOSE: Cerebral perfusion is commonly assessed clinically with dynamic susceptibility contrast MRI using a bolus injection of gadolinium-based contrast agents, resulting in semi-quantitative values of cerebral blood volume (CBV). Steady-state imaging with ferumoxytol allows estimation of CBV with the potential for higher precision and accuracy. Prior CBV studies have focused on the signal disrupting T2* effects, but ferumoxytol also has high signal-enhancing T1 relaxivity. The purpose of this study was to investigate and compare CBV estimation using T1 and T2*, with the goal of understanding the contrast mechanisms and quantitative differences...
November 2, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29090500/five-minute-knee-mri-for-simultaneous-morphometry-and-t2-relaxometry-of-cartilage-and-meniscus-and-for-semiquantitative-radiological-assessment-using-double-echo-in-steady-state-at-3t
#6
Akshay S Chaudhari, Marianne S Black, Susanne Eijgenraam, Wolfgang Wirth, Susanne Maschek, Bragi Sveinsson, Felix Eckstein, Edwin H G Oei, Garry E Gold, Brian A Hargreaves
BACKGROUND: Biomarkers for assessing osteoarthritis activity necessitate multiple MRI sequences with long acquisition times. PURPOSE: To perform 5-minute simultaneous morphometry (thickness/volume measurements) and T2 relaxometry of both cartilage and meniscus, and semiquantitative MRI Osteoarthritis Knee Scoring (MOAKS). STUDY TYPE: Prospective. SUBJECTS: Fifteen healthy volunteers for morphometry and T2 measurements, and 15 patients (five each Kellgren-Lawrence grades 0/2/3) for MOAKS assessment...
November 1, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29067745/human-umbilical-cord-blood-relaxation-times-and-susceptibility-at-3-t
#7
Sharon Portnoy, Natasha Milligan, Mike Seed, John G Sled, Christopher K Macgowan
PURPOSE: To characterize the magnetic susceptibility and relaxation times (T1 and T2 ) of fetal blood at 3 T as a function of the hematocrit (Hct) and oxygen saturation (sO2 ). METHODS: Susceptibility and relaxometry measurements were performed on cord blood specimens (N = 90, derived from six caesarean deliveries) with a range of hematocrits and oxygen saturations (0.09 < Hct < 0.82, 7 < sO2  < 100%). To obtain simple, analytic relationships between MRI properties and blood properties, data were fit to established two-compartment (plasma and erythrocytes) models...
October 24, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29064775/uspio-positive-ms-lesions-are-associated-with-greater-tissue-damage-than-gadolinium-positive-only-lesions-during-3-year-follow-up
#8
Anne Kerbrat, Benoit Combès, Olivier Commowick, Adil Maarouf, Elise Bannier, Jean Christophe Ferré, Ayman Tourbah, Jean-Philippe Ranjeva, Christian Barillot, Gilles Edan
BACKGROUND: Identifying in vivo the processes that determine lesion severity in multiple sclerosis (MS) remains a challenge. OBJECTIVES: To describe the dynamics of ultrasmall superparamagnetic iron oxide (USPIO) enhancement in MS lesions and the relationship between USPIO enhancement and microstructural changes over 3 years. METHODS: Lesion development was assessed at baseline, Months 3, 6, and 9, using magnetic resonance imaging (MRI) with gadolinium and USPIO...
October 1, 2017: Multiple Sclerosis: Clinical and Laboratory Research
https://www.readbyqxmd.com/read/29064019/stability-of-mri-metrics-in-the-advanced-research-core-of-the-ncaa-dod-concussion-assessment-research-and-education-care-consortium
#9
Andrew S Nencka, Timothy B Meier, Yang Wang, L Tugan Muftuler, Yu-Chien Wu, Andrew J Saykin, Jaroslaw Harezlak, M Alison Brooks, Christopher C Giza, John Difiori, Kevin M Guskiewicz, Jason P Mihalik, Stephen M LaConte, Stefan M Duma, Steven Broglio, Thomas McAllister, Michael A McCrea, Kevin M Koch
The NCAA-DoD Concussion Assessment, Research, and Education (CARE) consortium is performing a large-scale, comprehensive study of sport related concussions in college student-athletes and military service academy cadets. The CARE "Advanced Research Core" (ARC), is focused on executing a cutting-edge investigative protocol on a subset of the overall CARE athlete population. Here, we present the details of the CARE ARC MRI acquisition and processing protocol along with preliminary analyzes of within-subject, between-site, and between-subject stability across a variety of MRI biomarkers...
October 24, 2017: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/29058039/agreement-between-manual-relaxometry-and-semi-automated-scanner-based-multi-echo-dixon-technique-for-measuring-liver-t2-in-a-pediatric-and-young-adult-population
#10
Suraj D Serai, Ethan A Smith, Andrew T Trout, Jonathan R Dillman
BACKGROUND: Commercially available 3D multi-echo Dixon (mDixon) sequences provide parametric maps of liver T2*, obviating manual curve fitting that is often required with conventional gradient recalled echo (GRE)-based multi-echo relaxometry, potentially simplifying clinical work flow. OBJECTIVE: The purpose of our study was to compare T2* values generated by a 3D mDixon sequence to values generated by GRE-based T2* relaxometry with manual curve fitting in a pediatric and young adult population...
October 23, 2017: Pediatric Radiology
https://www.readbyqxmd.com/read/29051208/redefining-the-pulvinar-sign-in-fabry-disease
#11
S Cocozza, C Russo, A Pisani, G Olivo, E Riccio, A Cervo, G Pontillo, S Feriozzi, M Veroux, Y Battaglia, D Concolino, F Pieruzzi, R Mignani, P Borrelli, M Imbriaco, A Brunetti, E Tedeschi, G Palma
BACKGROUND AND PURPOSE: The pulvinar sign refers to exclusive T1WI hyperintensity of the lateral pulvinar. Long considered a common sign of Fabry disease, the pulvinar sign has been reported in many pathologic conditions. The exact incidence of the pulvinar sign has never been tested in representative cohorts of patients with Fabry disease. The aim of this study was to assess the prevalence of the pulvinar sign in Fabry disease by analyzing T1WI in a large Fabry disease cohort, determining whether relaxometry changes could be detected in this region independent of the pulvinar sign positivity...
October 19, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/29035038/dynamics-and-morphology-of-nanoparticle-linked-polymers-elucidated-by-nuclear-magnetic-resonance
#12
Yongqian Zhang, Charles G Fry, Joel A Pedersen, Robert J Hamers
Nanoparticles are frequently modified with polymer layers to control their physical and chemical properties, but little is understood about the morphology and dynamics of these polymer layers. We report here an NMR-based investigation of a model polymer-modified nanoparticle, using multiple NMR techniques including (1)H NMR, diffusion-ordered spectroscopy (DOSY), total correlation spectroscopy (TOCSY), and T2 relaxometry to characterize the dynamics of the nanoparticle-polymer interface. Using 5 nm detonation nanodiamond covalently linked to poly(allylamine) hydrochloride as a model system, we demonstrate the use of NMR to distinguish between free and bound polymer and to characterize the degree to which the segments of the nanoparticle-wrapping polymer are mobile (loops and tails) versus immobile (trains)...
November 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29030674/magnetic-resonance-neurography-normal-values-and-demographic-determinants-of-nerve-caliber-and-t2-relaxometry-in-60-healthy-individuals
#13
Moritz Kronlage, Véronique Schwehr, Daniel Schwarz, Tim Godel, Sabine Heiland, Martin Bendszus, Philipp Bäumer
PURPOSE: To establish normal values and to identify demographic determinants of quantitative biomarkers in magnetic resonance neurography (MRN). METHODS: In this study 60 healthy individuals (5 men and 5 women of every decade between 20 and 80 years) were examined according to a standardized MRN protocol at 3 T, including multiecho T2 relaxometry. Nerve cross-sectional area (CSA), transverse relaxation time (T2), and proton spin density (PSD) were assessed for the sciatic, tibial, median, ulnar, and radial nerves...
October 13, 2017: Clinical Neuroradiology
https://www.readbyqxmd.com/read/29021778/the-combined-quantification-and-interpretation-of-multiple-quantitative-magnetic-resonance-imaging-metrics-enlightens-longitudinal-changes-compatible-with-brain-repair-in-relapsing-remitting-multiple-sclerosis-patients
#14
Guillaume Bonnier, Benedicte Maréchal, Mário João Fartaria, Pavel Falkowskiy, José P Marques, Samanta Simioni, Myriam Schluep, Renaud Du Pasquier, Jean-Philippe Thiran, Gunnar Krueger, Cristina Granziera
OBJECTIVE: Quantitative and semi-quantitative MRI (qMRI) metrics provide complementary specificity and differential sensitivity to pathological brain changes compatible with brain inflammation, degeneration, and repair. Moreover, advanced magnetic resonance imaging (MRI) metrics with overlapping elements amplify the true tissue-related information and limit measurement noise. In this work, we combined multiple advanced MRI parameters to assess focal and diffuse brain changes over 2 years in a group of early-stage relapsing-remitting MS patients...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28964009/magnetic-response-of-a-viscoelastic-ferrodispersion-from-a-nearly-newtonian-ferrofluid-to-a-jeffreys-ferrogel
#15
V V Rusakov, Yu L Raikher
The theory of orientational motion of a Brownian magnetic nanoparticle embedded in a viscoelastic medium and subjected to a time-dependent uniform magnetic field is developed. The rheology of the viscoelastic environment of the particle is modeled by the Jeffreys scheme, which under variation of a minimal number of parameters is able to resemble a wide range of soft materials: from a weakly structured (nearly Newtonian) polymer solution to a gel. It is shown that in the Jeffreys model, the diffusional orientational motion of a particle is a combination of two modes, which could be associated with a fast motion within the polymer mesh cell and a slow displacement that involves deformation of the mesh, respectively...
September 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28936889/t2-relaxometry-mapping-in-demonstrating-layered-uterine-architecture-parameter-optimization-and-utility-in-endometrial-carcinoma-and-adenomyosis-a-feasibility-study
#16
Adarsh Ghosh, Tulika Singh, Rashmi Bagga, Radhika Srinivasan, Veenu Singla, Niranjan Khandelwal
OBJECTIVE: We evaluate the feasibility of T2 relaxometry mapping of the uterus and demonstrate its diagnostic utility in endometrial carcinoma and adenomyosis and discuss the optimum imaging parameters as used in our institute. METHODS: Institute review board approval was obtained and multispin echo (MSE) imaging of the pelvis was done with variable time to echo in three patients, two with endometrial carcinoma and one with adenomyosis. T2 parametric maps and curves were plotted and the T2 times of the diseased endometrium, superficial and deep myometrium were established...
October 27, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28935961/field-cycling-nmr-with-high-resolution-detection-under-magic-angle-spinning-determination-of-field-window-for-nuclear-hyperpolarization-in-a-photosynthetic-reaction-center
#17
Daniel Gräsing, Pavlo Bielytskyi, Isaac F Céspedes-Camacho, A Alia, Thorsten Marquardsen, Frank Engelke, Jörg Matysik
Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28935239/te-dependent-diffusion-imaging-teddi-distinguishes-between-compartmental-t2-relaxation-times
#18
Jelle Veraart, Dmitry S Novikov, Els Fieremans
Biophysical modeling of macroscopic diffusion-weighted MRI signal in terms of microscopic cellular parameters holds the promise of quantifying the integrity of white matter. Unfortunately, even fairly simple multi-compartment models of proton diffusion in the white matter do not provide a unique, biophysically plausible solution. Here we report a nontrivial diffusion MRI signal dependence on echo time (TE) in human white matter in vivo. We demonstrate that such TE dependence originates from compartment-specific T2 values and that it is a promising "orthogonal measure" able to break the degeneracy in parameter estimation, and to yield important relaxation metrics robustly...
September 19, 2017: NeuroImage
https://www.readbyqxmd.com/read/28928507/characteristics-of-xanthosoma-sagittifolium-roots-during-cooking-using-physicochemical-analysis-uniaxial-compression-multispectral-imaging-and-low-field-nmr-spectroscopy
#19
Abena Achiaa Boakye, María Gudjónsdóttir, Jacob Lercke Skytte, Ioannis S Chronakis, Faustina Dufie Wireko-Manu, Ibok Oduro
To effectively promote the industrial utilization of cocoyam (Xanthosoma sagittifolium) roots for enhanced food sustainability and security, there is a need to study their molecular, mechanical and physicochemical properties in detail. The physicochemical and textural characteristics of the red and white varieties of cocoyam roots were thus analysed by low field nuclear magnetic resonance relaxometry, multispectral imaging, uniaxial compression testing, and relevant physicochemical analysis in the current study...
August 2017: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/28923493/diagnosis-and-quantification-of-the-iron-overload-through-magnetic-resonance
#20
J M Alústiza Echeverría, M C Barrera Portillo, A Guisasola Iñiguiz, A Ugarte Muño
There are different magnetic resonance techniques and models to quantify liver iron concentration. T2 relaxometry methods evaluate the iron concentration in the myocardium, and they are able to discriminate all the levels of iron overload in the liver. Signal intensity ratio methods saturate with high levels of liver overload and can not assess iron concentration in the myocardium but they are more accessible and are very standardized. This article reviews, in different clinical scenarios, when Magnetic Resonance must be used to assess iron overload in the liver and myocardium and analyzes the current challenges to optimize the aplication of the technique and to be it included in the clinical guidelines...
November 2017: Radiología
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