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Relaxometry

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https://www.readbyqxmd.com/read/28432403/bone-marrow-fat-content-in-70-adolescent-girls-with-anorexia-nervosa-magnetic-resonance-imaging-and-magnetic-resonance-spectroscopy-assessment
#1
Kirsten Ecklund, Sridhar Vajapeyam, Robert V Mulkern, Henry A Feldman, Jennifer M O'Donnell, Amy D DiVasta, Catherine M Gordon
BACKGROUND: Adolescents and women with anorexia nervosa have increased bone marrow fat and decreased bone formation, at least in part due to hormonal changes leading to preferential stem cell differentiation to adipocytes over osteoblasts. OBJECTIVE: The purpose of this study was to evaluate marrow fat content and correlate with age and disease severity using knee MRI with T1 relaxometry (T1-R) and MR spectroscopy (MRS) in 70 adolescents with anorexia nervosa. MATERIALS AND METHODS: We enrolled 70 girls with anorexia nervosa who underwent 3-T knee MRI with coronal T1-W images, T1-R and single-voxel proton MRS at 30 and 60 ms TE...
April 22, 2017: Pediatric Radiology
https://www.readbyqxmd.com/read/28431589/t2-relaxometry-helps-prognosticate-seizure-outcome-in-patients-with-solitary-cerebral-cysticercosis
#2
Aaron de Souza, Atchayaram Nalini, Jitender Saini, Kandavel Thennarasu
OBJECTIVE: Correlate serial T2 relaxometry (T2R) values with long term seizure outcome in patients with solitary cerebral cysticercosis (SCC) in order to establish its usefulness as a prognostic marker in these patients. METHODS: Patients with new-onset seizures due to SCC were imaged serially using a pre-determined MRI protocol at enrolment and after 3, 6, 12 and 24months. T2 relaxometry was performed using a dual echo sequence with maps generated manually from the measured image intensities at the level of the lesion...
May 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28425543/in-situ-nuclear-magnetic-resonance-microimaging-of-live-biofilms-in-a-microchannel
#3
R S Renslow, M J Marshall, A E Tucker, W B Chrisler, X-Y Yu
Biofilms are comprised of microbial cells and an extracellular polymeric substance (EPS) matrix that supports interactions between community members and with the local environment. The highly hydrated EPS matrix makes the application of many biofilm visualization techniques difficult. Hence, to better visualize how biofilms interact with their environment, there is a need for imaging techniques to monitor hydrated state biofilm dynamics. We employed an in situ dynamic approach to construct label-free images of biofilms...
April 20, 2017: Analyst
https://www.readbyqxmd.com/read/28418846/drug-carrying-microbubbles-as-a-theranostic-tool-in-convection-enhanced-delivery-for-brain-tumor-therapy
#4
Pin-Yuan Chen, Chih-Kuang Yeh, Po-Hung Hsu, Chung-Yin Lin, Chiung-Yin Huang, Kuo-Chen Wei, Hao-Li Liu
Convection-enhanced delivery (CED) is a promising technique for infusing a therapeutic agent through a catheter with a pressure gradient to create bulk flow for improving drug spread into the brain. So far, gadopentetate dimeglumine (Gd-DTPA) is the most commonly applied surrogate agent for predicting drug distribution through magnetic resonance imaging (MRI). However, Gd-DTPA provides only a short observation duration, and concurrent infusion provides an indirect measure of the exact drug distribution. In this study, we propose using microbubbles as a contrast agent for MRI monitoring, and evaluate their use as a drug-carrying vehicle to directly monitor the infused drug...
March 15, 2017: Oncotarget
https://www.readbyqxmd.com/read/28405651/structure-and-dynamics-of-nh2-ch3-2-3sb2cl9-by-means-of-1-h-nmr-relaxometry-quadrupolar-relaxation-enhancement-effects
#5
M Florek-Wojciechowska, R Jakubas, D Kruk
(1)H spin-lattice relaxation experiments have been performed for [NH2(CH3)2]3Sb2Cl9 (tris(dimethylammonium)nonachlorodiantimonate(iii)) in the temperature range of 253-313 K and a broad range of frequencies - from 4 kHz to 40 MHz. From the analysis of quadrupolar relaxation enhancement effects (quadrupolar peaks) associated with (14)N nuclei, two lattice sites characterized by different electric field gradient tensors have been revealed. The (14)N quadrupolar couplings and asymmetry parameters at these sites differ by a factor of about two...
April 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28401643/ultrafast-compartmentalized-relaxation-time-mapping-with-linear-algebraic-modeling
#6
Yi Zhang, Xiaoyang Liu, Jinyuan Zhou, Paul A Bottomley
PURPOSE: To dramatically accelerate compartmental-average longitudinal (T1 ) and transverse (T2 ) relaxation measurements using the minimal-acquisition linear algebraic modeling (SLAM) method, and to validate it in phantoms and humans. METHODS: Relaxation times were imaged at 3 Tesla in phantoms, in the abdomens of six volunteers, and in six brain tumor patients using standard inversion recovery and multi-spin-echo sequences. k-space was fully sampled to provide reference T1 and T2 measurements, and SLAM was performed using a limited set of phase encodes from central k-space...
April 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28367903/longitudinal-assessment-of-dentate-nuclei-relaxometry-during-massive-gadobutrol-exposure
#7
Enrico Tedeschi, Sirio Cocozza, Pasquale Borrelli, Lorenzo Ugga, Vincenzo Brescia Morra, Giuseppe Palma
We report the assessment of Dentate Nuclei (DN) R1 (1/T1) and R2* (1/R2*) values in a patient with relapsing-remitting Multiple Sclerosis, exposed to 22 standard (0.1 mmol/kg) doses of gadobutrol, who underwent eight relaxometric magnetic resonance (MR) measurements within two years. DN R1 did not significantly increase nor correlated with cumulative gadobutrol administration, even after a total dose of 130 ml. Likewise, DN R2* relaxometry remained unchanged. In conclusion, massive gadobutrol exposure did not induce significant DN relaxometry changes...
March 27, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28358656/dynamics-of-white-matter-plasticity-underlying-working-memory-training-multimodal-evidence-from-diffusion-mri-and-t2-relaxometry
#8
Claudia Metzler-Baddeley, Sonya Foley, Silvia de Santis, Cyril Charron, Adam Hampshire, Karen Caeyenberghs, Derek K Jones
Adaptive working memory (WM) training may lead to cognitive benefits that are associated with white matter plasticity in parietofrontal networks, but the underlying mechanisms remain poorly understood. We investigated white matter microstructural changes after adaptive WM training relative to a nonadaptive comparison group. Microstructural changes were studied in the superior longitudinal fasciculus, the main parietofrontal connection, and the cingulum bundle as a comparison pathway. MRI-based metrics were the myelin water fraction and longitudinal relaxation rate R1 from multicomponent T2 relaxometry (captured with the mcDESPOT approach) as proxy metrics of myelin, the restricted volume fraction from the composite hindered and restricted model of diffusion as an estimate of axon morphology, and fractional anisotropy and radial diffusivity from diffusion tensor imaging...
March 30, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28338417/a-3d-tissue-printing-approach-for-validation-of-diffusion-tensor-imaging-in-skeletal-muscle
#9
David B Berry, Shangting You, John Warner, Lawrence R Frank, Shaochen Chen, Samuel R Ward
The ability to noninvasively assess skeletal muscle microstructure, which predicts function and disease, would be of significant clinical value. One method that holds this promise is diffusion tensor magnetic resonance imaging (DT-MRI), which is sensitive to the microscopic diffusion of water within tissues and has become ubiquitous in neuroimaging as a way of assessing neuronal structure and damage. However, its application to the assessment of changes in muscle microstructure associated with injury, pathology, or age remains poorly defined, because it is difficult to precisely control muscle microstructural features in vivo...
March 24, 2017: Tissue Engineering. Part A
https://www.readbyqxmd.com/read/28317922/optical-imaging-of-localized-chemical-events-using-programmable-diamond-quantum-nanosensors
#10
Torsten Rendler, Jitka Neburkova, Ondrej Zemek, Jan Kotek, Andrea Zappe, Zhiqin Chu, Petr Cigler, Jörg Wrachtrup
Development of multifunctional nanoscale sensors working under physiological conditions enables monitoring of intracellular processes that are important for various biological and medical applications. By attaching paramagnetic gadolinium complexes to nanodiamonds (NDs) with nitrogen-vacancy (NV) centres through surface engineering, we developed a hybrid nanoscale sensor that can be adjusted to directly monitor physiological species through a proposed sensing scheme based on NV spin relaxometry. We adopt a single-step method to measure spin relaxation rates enabling time-dependent measurements on changes in pH or redox potential at a submicrometre-length scale in a microfluidic channel that mimics cellular environments...
March 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28303617/joint-system-relaxometry-jsr-and-cr%C3%A3-mer-rao-lower-bound-optimization-of-sequence-parameters-a-framework-for-enhanced-precision-of-despot-t1-and-t2-estimation
#11
Rui Pedro A G Teixeira, Shaihan J Malik, Joseph V Hajnal
PURPOSE: This study aims to increase the precision of single-compartment DESPOT relaxometry by two means: (i) a joint system relaxometry (JSR) approach that estimates parameters in a single step using all available data; and (ii) optimizing acquisition parameters by deploying a robust design tool based on the Crámer-Rao lower bound (CRLB). METHODS: Following the development of the analysis and design capabilities, phantom and four in vivo subject experiments were performed to compare directly the precision achieved with DESPOT and JSR estimation using published protocols and protocols designed using a proposed CRLB framework...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28281697/measurement-and-visualization-of-tight-rock-exposed-to-co2-using-nmr-relaxometry-and-mri
#12
Haitao Wang, Zengmin Lun, Chengyuan Lv, Dongjiang Lang, Bingyu Ji, Ming Luo, Weiyi Pan, Rui Wang, Kai Gong
Understanding mechanisms of oil mobilization of tight matrix during CO2 injection is crucial for CO2 enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO2 and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR T2) spectrum and magnetic resonance imaging (MRI) under the reservoir pressure and temperature. Quantitative analysis of recovery at the pore scale and visualization of oil mobilization are achieved...
March 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28276684/ultrasound-induced-magnetic-imaging-of-tumors-targeted-by-biofunctional-magnetic-nanoparticles
#13
Kai-Wen Huang, Jen-Jie Chieh, Chih-Kuang Yeh, Shu-Hsien Liao, Yi-Yan Lee, Pei-Yi Hsiao, Wen-Chun Wei, Hong-Chang Yang, Herng-Er Horng
Biofunctional magnetic nanoparticles (MNPs) have been widely applied in biomedical engineering. MNPs are used as a contrast medium in magnetic imaging. Current methods of magnetic imaging, such as magnetic particle imaging and magnetic relaxometry, use small amounts of MNPs at target points far from the surface of the patient's body; these methods always consume considerable power to produce magnetic fields of high uniformity or gradient excitations. Some drawbacks, such as a limited imaging region, imaging system shielding, and complex algorithms based on assumptions of MNP properties or environmental factors, also limit the application of MNP methods in clinics...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28267532/r2-relaxometry-of-the-pancreas-in-patients-with-human-hemochromatosis-protein-associated-hereditary-hemochromatosis
#14
B Henninger, S Rauch, H Zoller, M Plaikner, W Jaschke, C Kremser
PURPOSE: To evaluate pancreatic iron in patients with human hemochromatosis protein associated hereditary hemochromatosis (HHC) using R2* relaxometry. MATERIALS AND METHODS: 81 patients (58 male, 23 female; median age 49.5, range 10-81 years) with HHC were retrospectively studied. All underwent 1.5T magnetic resonance imaging (MRI) of the abdomen. A fat-saturated multi-gradient echo sequence with 12 echoes (TR=200ms; TE-initial 0.99ms; Delta-TE 1.41ms; 12 echoes; flip-angle: 20°) was used for the R2* quantification of the liver and the pancreas...
April 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28267494/aggregation-and-gelation-of-oat-%C3%AE-glucan-in-aqueous-solution-probed-by-nmr-relaxometry
#15
Jia Wu, Lan Zhao, Jian Li, Shanshan Jin, Shanshan Wu
Nuclear magnetic resonance was used to study water proton transverse relaxation in oat β-glucan aqueous solutions during storage. The molecular weights of the samples ranged from 112 to 494kDa. The polysaccharide structure was identified by IR, GC-MS, NMR spectroscopy, and high performance anion exchange chromatography. In 1% solutions, 494kDa β-glucan formed stable solution phase. Aggregates were generated in the solution of low molecular weight polysaccharide. The transverse relaxation time of water associated with the aggregate microphase was about 15ms...
May 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28266528/gd-eob-dtpa-enhanced-mri-for-evaluation-of-liver-function-comparison-between-signal-intensity-based-indices-and-t1-relaxometry
#16
Michael Haimerl, Niklas Verloh, Florian Zeman, Claudia Fellner, Dominik Nickel, Sven A Lang, Andreas Teufel, Christian Stroszczynski, Philipp Wiggermann
Gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a paramagnetic hepatobiliary magnetic resonance (MR) contrast agent. Due to its OATP1B1/B3-dependent hepatocyte-specific uptake and paramagnetic properties increasing evidence has emerged to suggest that Gd-EOB-DTPA-enhanced MRI can be potentially used for evaluation of liver function. In this paper we compare the diagnostic performance of Gd-EOB-DTPA-enhanced relaxometry-based and commonly used signal-intensity (SI)-based indices, including the hepatocellular uptake index (HUI) and SI-based indices corrected by spleen or muscle, for evaluation of liver function, determined using the Indocyanin green clearance (ICG) test...
March 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28222197/generalized-min-max-bound-based-mri-pulse-sequence-design-framework-for-wide-range-t1-relaxometry-a-case-study-on-the-tissue-specific-imaging-sequence
#17
Yang Liu, John R Buck, Vasiliki N Ikonomidou
This paper proposes a new design strategy for optimizing MRI pulse sequences for T1 relaxometry. The design strategy optimizes the pulse sequence parameters to minimize the maximum variance of unbiased T1 estimates over a range of T1 values using the Cramér-Rao bound. In contrast to prior sequences optimized for a single nominal T1 value, the optimized sequence using our bound-based strategy achieves improved precision and accuracy for a broad range of T1 estimates within a clinically feasible scan time. The optimization combines the downhill simplex method with a simulated annealing process...
2017: PloS One
https://www.readbyqxmd.com/read/28213048/low-field-single-sided-nmr-for-one-shot-1d-mapping-application-to-membranes
#18
Patrick Judeinstein, Filippo Ferdeghini, Rodrigo Oliveira-Silva, Jean-Marc Zanotti, Dimitrios Sakellariou
Many single-sided permanent magnet NMR systems have been proposed over the years allowing for 1D proton-density profiling, diffusion measurements and relaxometry. In this manuscript we make use of a recently published unilateral magnet for low-field NMR exhibiting an extremely uniform magnetic field gradient with moderate strength and cylindrical symmetry, allowing for a well-defined sweet spot. Combined with a goniometer, our system is used to characterize precisely the uniformity of its gradient and to achieve micrometric precision 1D profiling, as well as spatially localized relaxometry and diffusometry on thick (∼150μm) membrane samples...
February 8, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28194423/effects-of-liver-fibrosis-progression-on-tissue-relaxation-times-in-different-mouse-models-assessed-by-ultrahigh-field-magnetic-resonance-imaging
#19
Andreas Müller, Katrin Hochrath, Jonas Stroeder, Kanishka Hittatiya, Günther Schneider, Frank Lammert, Arno Buecker, Peter Fries
Recently, clinical studies demonstrated that magnetic resonance relaxometry with determination of relaxation times T1 and T2(⁎) may aid in staging and management of liver fibrosis in patients suffering from viral hepatitis and steatohepatitis. In the present study we investigated T1 and T2(⁎) in different models of liver fibrosis to compare alternate pathophysiologies in their effects on relaxation times and to further develop noninvasive quantification methods of liver fibrosis. MRI was performed with a fast spin echo sequence for measurement of T1 and a multigradient echo sequence for determination of T2(⁎)...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28191646/non-invasive-evaluation-of-blood-oxygen-saturation-and-hematocrit-from-t1-and-t2-relaxation-times-in-vitro-validation-in-fetal-blood
#20
Sharon Portnoy, Mike Seed, John G Sled, Christopher K Macgowan
PURPOSE: We propose an analytical method for calculating blood hematocrit (Hct) and oxygen saturation (sO2 ) from measurements of its T1 and T2 relaxation times. THEORY: Through algebraic substitution, established two-compartment relationships describing R1=T1-1 and R2=T2-1 as a function of hematocrit and oxygen saturation were rearranged to solve for Hct and sO2 in terms of R1 and R2 . Resulting solutions for Hct and sO2 are the roots of cubic polynomials. METHODS: Feasibility of the method was established by comparison of Hct and sO2 estimates obtained from relaxometry measurements (at 1...
February 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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