keyword
MENU ▼
Read by QxMD icon Read
search

Relaxometry

keyword
https://www.readbyqxmd.com/read/29336598/quantitative-mr-evaluation-of-chronic-pancreatitis-extracellular-volume-fraction-and-mr-relaxometry
#1
Temel Tirkes, Chen Lin, Enming Cui, Yu Deng, Paul R Territo, Kumaresan Sandrasegaran, Fatih Akisik
OBJECTIVE: The purpose of this study was to determine if extracellular volume fraction and T1 mapping can be used to diagnose chronic pancreatitis (CP). MATERIALS AND METHODS: This HIPAA-compliant study analyzed 143 consecutive patients with and without CP who underwent MR imaging between May 2016 and February 2017. Patients were selected for the study according to inclusion and exclusion criteria that considered history and clinical and laboratory findings. Eligible patients (n = 119) were grouped as normal (n = 60) or with mild (n = 22), moderate (n = 27), or severe (n = 10) CP on the basis of MRCP findings using the Cambridge classification as the reference standard...
January 16, 2018: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/29315714/brain-abnormalities-in-cognition-anxiety-and-depression-regulatory-regions-in-adolescents-with-single-ventricle-heart-disease
#2
Nancy A Pike, Bhaswati Roy, Ritika Gupta, Sadhana Singh, Mary A Woo, Nancy J Halnon, Alan B Lewis, Rajesh Kumar
BACKGROUND: Single ventricle heart disease (SVHD) adolescents show cognitive impairments and anxiety and depressive symptoms, indicating the possibility of brain injury in regions that control these functions. However, brain tissue integrity in cognition, anxiety, and depression regulatory sites in SVHD remains unclear. We examined brain tissue changes in SVHD compared to controls using T2-relaxometry procedures, which measure free water content and show tissue injury. METHODS: Proton-density and T2-weighted images, using a 3...
January 6, 2018: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/29305910/the-development-of-brain-white-matter-microstructure
#3
Catherine Lebel, Sean Deoni
Throughout infancy, childhood, and adolescence, our brains undergo remarkable changes. Processes including myelination and synaptogenesis occur rapidly across the first 2-3 years of life, and ongoing brain remodeling continues into young adulthood. Studies have sought to characterize the patterns of structural brain development, and early studies predominately relied upon gross anatomical measures of brain structure, morphology, and organization. MRI offers the ability to characterize and quantify a range of microstructural aspects of brain tissue that may be more closely related to fundamental neurodevelopmental processes...
January 3, 2018: NeuroImage
https://www.readbyqxmd.com/read/29305163/inferring-brain-tissue-composition-and-microstructure-via-mr-relaxometry
#4
REVIEW
Mark D Does
MRI relaxometry is sensitive to a variety of tissue characteristics in a complex manner, which makes it both attractive and challenging for characterizing tissue. This article reviews the most common water proton relaxometry measures, T1, T2, and T2*, and reports on their development and current potential to probe the composition and microstructure of brain tissue. The development of these relaxometry measures is challenged by the need for suitably accurate tissue models, as well as robust acquisition and analysis methodologies...
January 2, 2018: NeuroImage
https://www.readbyqxmd.com/read/29296621/rivastigmine-decreases-brain-damage-in-hiv-patients-with-mild-cognitive-deficits
#5
Gaetano Perrotta, Guillaume Bonnier, Djalel-Eddine Meskaldji, David Romascano, Ruslan Aydarkhanov, Alessandro Daducci, Samanta Simioni, Matthias Cavassini, Melanie Metral, François Lazeyras, Reto Meuli, Gunnar Krueger, Renaud A Du Pasquier, Cristina Granziera
Rivastigmine has been shown to improve cognition in HIV+ patients with minor neurocognitive disorders; however, the mechanisms underlying such beneficial effect are currently unknown. To assess whether rivastigmine therapy is associated with decreased brain inflammation and damage, we performed T1/T2* relaxometry and magnetization transfer imaging in 17 aviremic HIV+ patients with minor neurocognitive disorders enrolled on a crossed over randomized rivastigmine trial. Rivastigmine therapy was associated with changes in MRI metrics indicating a decrease in brain water content (i...
December 2017: Annals of Clinical and Translational Neurology
https://www.readbyqxmd.com/read/29295619/variable-temperature-nuclear-magnetic-resonance-and-magnetic-resonance-imaging-system-as-a-novel-technique-for-in-situ-monitoring-food-phase-transition
#6
Yukun Song, Shasha Cheng, Huihui Wang, Bei-Wei Zhu, Dayong Zhou, Peiqiang Yang, Mingqian Tan
A nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system with a 45 mm variable temperature (VT) sample probe (VT-NMR-MRI) was developed as an innovative technique for in situ monitoring of food phase transition. The system was designed to allow for dual deployment either in a freezing (-37 oC) or a high temperature (150 oC). The major breakthrough of the developed VT-NMR-MRI system is that it is able to measure the water states simultaneously in situ during food processing. The performance of the VT-NMR-MRI system was evaluated by measuring the phase transition for salmon flesh and hen egg samples...
January 2, 2018: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29279106/proton-nmr-relaxometry-as-probe-of-gelatinization-plasticization-and-montmorillonite-loading-effects-on-starch-based-materials
#7
Roberto Pinto Cucinelli Neto, Elton Jorge da Rocha Rodrigues, Maria Inês Bruno Tavares
The effects of granule disruption, the addition of glycerol and montmorillonite on the granule structure of corn starch were investigated by proton NMR relaxation, through the T2*, T1 and T1ρ relaxation times. Films containing 0%, 1%, 5% and 7%(w/w) of clay were prepared by solution casting and the relaxometry data were compared with those gleaned from WAXD, TGA and SEM techniques. Starch gelatinization without glycerol or clay results in an amorphous and rigid film having a dipole coupling higher than that observed for the granule...
February 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29278792/increasing-water-solubility-with-decreasing-droplet-size-limits-the-use-of-water-nmr-diffusometry-in-submicron-w-o-emulsion-droplet-size-analysis
#8
Mathieu Balcaen, Lorenz De Neve, Lien Vermeir, Timothee Courtin, Koen Dewettinck, Davy Sinnaeve, Paul Van der Meeren
HYPOTHESIS: Water droplet size analysis of water-in-oil emulsions using water NMR diffusometry yielded values that were, from a certain shear intensity onwards, independent from the shear which was used during production. It was assumed that the constant water droplet size, obtained for samples prepared at higher shear, were only apparent droplet diameters. Considering the well-known increased solubility of the dispersed phase in the continuous phase at smaller droplet sizes, it is hypothesized that water diffusion in the oil phase was responsible for the fact that apparent rather than real sizes were obtained...
December 19, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29261786/resume-turning-an-swi-acquisition-into-a-fast-qmri-protocol
#9
Serena Monti, Pasquale Borrelli, Enrico Tedeschi, Sirio Cocozza, Giuseppe Palma
Susceptibility Weighted Imaging (SWI) is a common MRI technique that exploits the magnetic susceptibility differences between the tissues to provide valuable image contrasts, both in research and clinical contexts. However, despite its increased clinical use, SWI is not intrinsically suitable for quantitation purposes. Conversely, quantitative Magnetic Resonance Imaging (qMRI) provides a way to disentangle the sources of common MR image contrasts (e.g. proton density, T1, etc.) and to measure physical parameters intrinsically related to tissue microstructure...
2017: PloS One
https://www.readbyqxmd.com/read/29258604/water-t2-as-an-early-global-and-practical-biomarker-for-metabolic-syndrome-an-observational-cross-sectional-study
#10
Michelle D Robinson, Ina Mishra, Sneha Deodhar, Vipulkumar Patel, Katrina V Gordon, Raul Vintimilla, Kim Brown, Leigh Johnson, Sid O'Bryant, David P Cistola
BACKGROUND: Metabolic syndrome (MetS) is a highly prevalent condition that identifies individuals at risk for type 2 diabetes mellitus and atherosclerotic cardiovascular disease. Prevention of these diseases relies on early detection and intervention in order to preserve pancreatic β-cells and arterial wall integrity. Yet, the clinical criteria for MetS are insensitive to the early-stage insulin resistance, inflammation, cholesterol and clotting factor abnormalities that characterize the progression toward type 2 diabetes and atherosclerosis...
December 19, 2017: Journal of Translational Medicine
https://www.readbyqxmd.com/read/29243295/extended-phase-graph-formalism-for-systems-with-magnetization-transfer-and-exchange
#11
Shaihan J Malik, Rui Pedro A G Teixeira, Joseph V Hajnal
PURPOSE: An extended phase graph framework (EPG-X) for modeling systems with exchange or magnetization transfer (MT) is proposed. THEORY: EPG-X models coupled two-compartment systems by describing each compartment with separate phase graphs that exchange during evolution periods. There are two variants: EPG-X(BM) for systems governed by the Bloch-McConnell equations, and EPG-X(MT) for the pulsed MT formalism. For the MT case, the "bound" protons have no transverse components, so their phase graph consists of only longitudinal states...
December 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29232030/reproducibility-of-relaxometry-of-human-lumbar-vertebrae-at-3-tesla-using-1-h-mr-spectroscopy
#12
Bernhard Neumayer, Thomas Widek, Rudolf Stollberger, Eva Scheurer
BACKGROUND: MR spectroscopy is widely used for fat fraction quantification of human lumbar vertebrae. However, the measurements need to be corrected for relaxation effects. PURPOSE: The aim of this study was to determine the reproducibility of relaxometry in human lumbar vertebrae required for the correction of fat fraction measurements using magnetic resonance spectroscopy at 3 Tesla. Such information provides error estimates and guidance regarding reliability for future studies...
December 12, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29230908/desktop-nmr-and-its-applications-from-materials-science-to-organic-chemistry
#13
REVIEW
Bernhard Blümich, Kawarpal Singh
NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small-molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields...
December 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29227559/magnetic-resonance-measurements-of-tissue-quantity-and-quality-using-t2-relaxometry-predict-temporal-changes-in-the-biomechanical-properties-of-the-healing-acl
#14
Jillian E Beveridge, Jason T Machan, Edward G Walsh, Ata M Kiapour, N Padmini Karamchedu, Kaitlyn E Chin, Benedikt L Proffen, Jakob T Sieker, Martha M Murray, Braden C Fleming
The purpose of this study was to develop a magnetic resonance T2 * relaxometry-based multiple linear regression model to predict the structural properties of the healing anterior cruciate ligament (ACL) over a 24-week healing period following ACL repair in Yucatan minipigs. Two hypotheses were tested: (1) that a regression model based on ACL sub-volumes containing short and long T2 * relaxation times would outperform a competing model based on sub-volumes of short T2 * relaxation times only; and (2) that an optimized regression model would be capable of predicting ACL structural properties between 6 and 24 weeks post-repair...
December 11, 2017: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
https://www.readbyqxmd.com/read/29215401/relaxivity-of-ferumoxytol-at-1-5-t-and-3-0-t
#15
Gesine Knobloch, Timothy Colgan, Curtis N Wiens, Xiaoke Wang, Tilman Schubert, Diego Hernando, Samir D Sharma, Scott Reeder
OBJECTIVES: The aim of this study was to determine the relaxation properties of ferumoxytol, an off-label alternative to gadolinium-based contrast agents, under physiological conditions at 1.5 T and 3.0 T. MATERIALS AND METHODS: Ferumoxytol was diluted in gradually increasing concentrations (0.26-4.2 mM) in saline, human plasma, and human whole blood. Magnetic resonance relaxometry was performed at 37°C at 1.5 T and 3.0 T. Longitudinal and transverse relaxation rate constants (R1, R2, R2*) were measured as a function of ferumoxytol concentration, and relaxivities (r1, r2, r2*) were calculated...
December 5, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/29213149/effect-of-rubber-polarity-on-cluster-formation-in-rubbers-cross-linked-with-diels-alder-chemistry
#16
L M Polgar, E Hagting, P Raffa, M Mauri, R Simonutti, F Picchioni, M van Duin
Diels-Alder chemistry has been used for the thermoreversible cross-linking of furan-functionalized ethylene/propylene (EPM) and ethylene/vinyl acetate (EVM) rubbers. Both furan-functionalized elastomers were successfully cross-linked with bismaleimide to yield products with a similar cross-link density. NMR relaxometry and SAXS measurements both show that the apolar EPM-g-furan precursor contains phase-separated polar clusters and that cross-linking with polar bismaleimide occurs in these clusters. The heterogeneously cross-linked network of EPM-g-furan contrasts with the homogeneous network in the polar EVM-g-furan...
November 28, 2017: Macromolecules
https://www.readbyqxmd.com/read/29205635/cerebral-white-matter-maturation-patterns-in-preterm-infants-an-mri-t2-relaxation-anisotropy-and-diffusion-tensor-imaging-study
#17
Michael J Knight, Adam Smith-Collins, Sarah Newell, Mark Denbow, Risto A Kauppinen
BACKGROUND AND PURPOSE: Preterm birth is associated with worse neurodevelopmental outcome, but brain maturation in preterm infants is poorly characterized with standard methods. We evaluated white matter (WM) of infant brains at term-equivalent age, as a function of gestational age at birth, using multimodal magnetic resonance imaging (MRI). METHODS: Infants born very preterm (<32 weeks gestation) and late preterm (33-36 weeks gestation) were scanned at 3 T at term-equivalent age using diffusion tensor imaging (DTI) and T2 relaxometry...
December 5, 2017: Journal of Neuroimaging: Official Journal of the American Society of Neuroimaging
https://www.readbyqxmd.com/read/29197695/probing-numerical-laplace-inversion-methods-for-two-and-three-site-molecular-exchange-between-interconnected-pore-structures
#18
Emilia V Silletta, María B Franzoni, Gustavo A Monti, Rodolfo H Acosta
Two-dimension (2D) Nuclear Magnetic Resonance relaxometry experiments are a powerful tool extensively used to probe the interaction among different pore structures, mostly in inorganic systems. The analysis of the collected experimental data generally consists of a 2D numerical inversion of time-domain data where T2-T2 maps are generated. Through the years, different algorithms for the numerical inversion have been proposed. In this paper, two different algorithms for numerical inversion are tested and compared under different conditions of exchange dynamics; the method based on Butler-Reeds-Dawson (BRD) algorithm and the fast-iterative shrinkage-thresholding algorithm (FISTA) method...
November 30, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29196268/developing-3d-microscopy-with-clarity-on-human-brain-tissue-towards-a-tool-for-informing-and-validating-mri-based-histology
#19
Markus Morawski, Evgeniya Kirilina, Nico Scherf, Carsten Jäger, Katja Reimann, Robert Trampel, Filippos Gavriilidis, Stefan Geyer, Bernd Biedermann, Thomas Arendt, Nikolaus Weiskopf
Recent breakthroughs in magnetic resonance imaging (MRI) enabled quantitative relaxometry and diffusion-weighted imaging with sub-millimeter resolution. Combined with biophysical models of MR contrast the emerging methods promise in vivo mapping of cyto- and myelo-architectonics, i.e., in vivo histology using MRI (hMRI) in humans. The hMRI methods require histological reference data for model building and validation. This is currently provided by MRI on post mortem human brain tissue in combination with classical histology on sections...
November 28, 2017: NeuroImage
https://www.readbyqxmd.com/read/29194739/transverse-signal-decay-under-the-weak-field-approximation-theory-and-validation
#20
Avery J L Berman, G Bruce Pike
PURPOSE: To derive an expression for the transverse signal time course from systems in the motional narrowing regime, such as water diffusing in blood. This was validated in silico and experimentally with ex vivo blood samples. METHODS: A closed-form solution (CFS) for transverse signal decay under any train of refocusing pulses was derived using the weak field approximation. The CFS was validated via simulations of water molecules diffusing in the presence of spherical perturbers, with a range of sizes and under various pulse sequences...
December 1, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
keyword
keyword
106411
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"