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NMR in Biomedicine

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https://www.readbyqxmd.com/read/28430379/-17-o-mrs-assesses-the-effect-of-mild-hypothermia-on-oxygen-consumption-rate-in-tumors
#1
Marie-Aline Neveu, Nicolas Joudiou, Géraldine De Preter, Jean-Paul Dehoux, Bénédicte F Jordan, Bernard Gallez
Although oxygen consumption is a key factor in metabolic phenotyping, its assessment in tumors remains critical, as current technologies generally display poor specificity. The objectives of this study were to explore the feasibility of direct (17) O nuclear magnetic resonance (NMR) spectroscopy to assess oxygen metabolism in tumors and its modulations. To investigate the impact of hypometabolism induction in the murine fibrosarcoma FSAII tumor model, we monitored the oxygen consumption of normothermic (37°C) and hypothermic (32°C) tumor-bearing mice...
April 21, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28383778/the-effect-of-noise-and-lipid-signals-on-determination-of-gaussian-and-non-gaussian-diffusion-parameters-in-skeletal-muscle
#2
Donnie Cameron, Mustapha Bouhrara, David A Reiter, Kenneth W Fishbein, Seongjin Choi, Christopher M Bergeron, Luigi Ferrucci, Richard G Spencer
This work characterizes the effect of lipid and noise signals on muscle diffusion parameter estimation in several conventional and non-Gaussian models, the ultimate objectives being to characterize popular fat suppression approaches for human muscle diffusion studies, to provide simulations to inform experimental work and to report normative non-Gaussian parameter values. The models investigated in this work were the Gaussian monoexponential and intravoxel incoherent motion (IVIM) models, and the non-Gaussian kurtosis and stretched exponential models...
April 6, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28370576/initial-investigation-of-glucose-metabolism-in-mouse-brain-using-enriched-17-o-glucose-and-dynamic-17-o-mrs
#3
Robert Borowiak, Wilfried Reichardt, Dmitry Kurzhunov, Christian Schuch, Jochen Leupold, Axel Joachim Krafft, Marco Reisert, Thomas Lange, Elmar Fischer, Michael Bock
In this initial work, the in vivo degradation of (17) O-labeled glucose was studied during cellular glycolysis. To monitor cellular glucose metabolism, direct (17) O-magnetic resonance spectroscopy (MRS) was used in the mouse brain at 9.4 T. Non-localized spectra were acquired with a custom-built transmit/receive (Tx/Rx) two-turn surface coil and a free induction decay (FID) sequence with a short TR of 5.4 ms. The dynamics of labeled oxygen in the anomeric 1-OH and 6-CH2 OH groups was detected using a Hankel-Lanczos singular value decomposition (HLSVD) algorithm for water suppression...
April 3, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28370463/retrospective-correction-of-frequency-drift-in-spectral-editing-the-gaba-editing-example
#4
Jan Willem van der Veen, Stefano Marenco, Karen F Berman, Jun Shen
GABA levels can be measured using proton MRS with a two-step editing sequence. However due to the low concentration of GABA, long acquisition time is usually needed to achieve sufficient SNR to detect small differences in many psychiatric disorders. During this long scan time the frequency offset of the measured voxel can change because of magnetic field drift and patient movement. This drift will change the frequency of the editing pulse relative to that of metabolites, leading to errors in quantification...
April 3, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28370884/detecting-in-vivo-urokinase-plasminogen-activator-activity-with-a-catalycest-mri-contrast-agent
#5
Sanhita Sinharay, Christine M Howison, Amanda F Baker, Mark D Pagel
Urokinase plasminogen activator (uPA) promotes tumor invasion and metastasis. The monitoring of uPA activity using molecular imaging may have prognostic value and be predictive for response to anti-cancer therapies. However, the detection of in vivo enzyme activity with molecular imaging remains a challenge. To address this problem, we designed a nonmetallic contrast agent, GR-4Am-SA, that can be detected with chemical exchange saturation transfer (CEST) MRI. This agent has a peptide that is cleaved by uPA, which causes a CEST signal at 5...
March 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28370530/noninvasive-evaluation-of-renal-ph-homeostasis-after-ischemia-reperfusion-injury-by-cest-mri
#6
Dario Livio Longo, Juan Carlos Cutrin, Filippo Michelotti, Pietro Irrera, Silvio Aime
Acute kidney injury (AKI) in mice caused by sustained ischemia followed by reperfusion is associated with acute tubular necrosis and renal dysfunctional blood flow. Although the principal role of the kidney is the maintenance of acid-base balance, current imaging approaches are unable to assess this important parameter, and clinical biomarkers are not robust enough in evaluating the severity of kidney damage. Therefore, novel noninvasive imaging approaches are needed to assess the acid-base homeostasis in vivo...
March 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28340292/combined-spiroergometry-and-31-p-mrs-of-human-calf-muscle-during-high-intensity-exercise
#7
K Moll, A Gussew, C Hein, N Stutzig, J R Reichenbach
Simultaneous measurements of pulmonary oxygen consumption (VO2 ), carbon dioxide exhalation (VCO2 ) and phosphorus magnetic resonance spectroscopy ((31) P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO2 and VCO2 whilst simultaneously performing (31) P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer...
March 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28328072/tensor-estimation-for-double-pulsed-diffusional-kurtosis-imaging
#8
Calvin B Shaw, Edward S Hui, Joseph A Helpern, Jens H Jensen
Double-pulsed diffusional kurtosis imaging (DP-DKI) represents the double diffusion encoding (DDE) MRI signal in terms of six-dimensional (6D) diffusion and kurtosis tensors. Here a method for estimating these tensors from experimental data is described. A standard numerical algorithm for tensor estimation from conventional (i.e. single diffusion encoding) diffusional kurtosis imaging (DKI) data is generalized to DP-DKI. This algorithm is based on a weighted least squares (WLS) fit of the signal model to the data combined with constraints designed to minimize unphysical parameter estimates...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28318071/resolution-limit-of-cylinder-diameter-estimation-by-diffusion-mri-the-impact-of-gradient-waveform-and-orientation-dispersion
#9
Markus Nilsson, Samo Lasič, Ivana Drobnjak, Daniel Topgaard, Carl-Fredrik Westin
Diffusion MRI has been proposed as a non-invasive technique for axonal diameter mapping. However, accurate estimation of small diameters requires strong gradients, which is a challenge for the transition of the technique from preclinical to clinical MRI scanners, since these have weaker gradients. In this work, we develop a framework to estimate the lower bound for accurate diameter estimation, which we refer to as the resolution limit. We analyse only the contribution from the intra-axonal space and assume that axons can be represented by impermeable cylinders...
March 20, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28318066/three-dimensional-ultrashort-echo-time-cones-t1%C3%AF-3d-ute-cones-t1%C3%AF-imaging
#10
Ya-Jun Ma, Michael Carl, Hongda Shao, Anthony S Tadros, Eric Y Chang, Jiang Du
We report a novel three-dimensional (3D) ultrashort echo time (UTE) sequence employing Cones trajectory and T1ρ preparation (UTE-Cones-T1ρ ) for quantitative T1ρ assessment of short T2 tissues in the musculoskeletal system. A basic 3D UTE-Cones sequence was combined with a spin-locking preparation pulse for T1ρ contrast. A relatively short TR was used to decrease the scan time, which required T1 measurement and compensation using 3D UTE-Cones data acquisitions with variable TRs. Another strategy to reduce the total scan time was to acquire multiple Cones spokes (Nsp ) after each T1ρ preparation and fat saturation...
March 20, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28301071/applications-of-high-resolution-magic-angle-spinning-mrs-in-biomedical-studies-i-cell-line-and-animal-models
#11
REVIEW
Eva Kaebisch, Taylor L Fuss, Lindsey A Vandergrift, Karin Toews, Piet Habbel, Leo L Cheng
High-resolution magic angle spinning (HRMAS) MRS allows for direct measurements of non-liquid tissue and cell specimens to present valuable insights into the cellular metabolisms of physiological and pathological processes. HRMAS produces high-resolution spectra comparable to those obtained from solutions of specimen extracts but without complex metabolite extraction processes, and preserves the tissue cellular structure in a form suitable for pathological examinations following spectroscopic analysis. The technique has been applied in a wide variety of biomedical and biochemical studies and become one of the major platforms of metabolomic studies...
March 16, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28295736/diffusion-prepared-stimulated-echo-turbo-spin-echo-dpsti-tse-an-eddy-current-insensitive-sequence-for-three-dimensional-high-resolution-and-undistorted-diffusion-weighted-imaging
#12
Qinwei Zhang, Bram F Coolen, Maarten J Versluis, Gustav J Strijkers, Aart J Nederveen
In this study, we present a new three-dimensional (3D), diffusion-prepared turbo spin echo sequence based on a stimulated-echo read-out (DPsti-TSE) enabling high-resolution and undistorted diffusion-weighted imaging (DWI). A dephasing gradient in the diffusion preparation module and rephasing gradients in the turbo spin echo module create stimulated echoes, which prevent signal loss caused by eddy currents. Near to perfect agreement of apparent diffusion coefficient (ADC) values between DPsti-TSE and diffusion-weighted echo planar imaging (DW-EPI) was demonstrated in both phantom transient signal experiments and phantom imaging experiments...
March 13, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28295818/accuracy-of-fully-automated-quantitative-volumetric-measurement-of-the-amount-of-fibroglandular-breast-tissue-using-mri-correlation-with-anthropomorphic-breast-phantoms
#13
Georg J Wengert, Katja Pinker, Thomas H Helbich, Wolf-Dieter Vogl, Sylvia M Spijker, Hubert Bickel, Stephan H Polanec, Pascal A Baltzer
To demonstrate the accuracy of fully automated, quantitative, volumetric measurement of the amount of fibroglandular breast tissue (FGT), using MRI, and to investigate the impact of different MRI sequences using anthropomorphic breast phantoms as the ground truth. In this study, 10 anthropomorphic breast phantoms that consisted of different known fractions of adipose and protein tissue, which closely resembled normal breast parenchyma, were developed. Anthropomorphic breast phantoms were imaged with a 1.5 T unit (Siemens, Avantofit) using an 18-channel breast coil...
March 10, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272795/inhibition-of-prostate-cancer-proliferation-by-deferiprone
#14
Rui V Simões, Suresh Veeraperumal, Inna S Serganova, Natalia Kruchevsky, Joseph Varshavsky, Ronald G Blasberg, Ellen Ackerstaff, Jason A Koutcher
Cancer growth and proliferation rely on intracellular iron availability. We studied the effects of Deferiprone (DFP), a chelator of intracellular iron, on three prostate cancer cell lines: murine, metastatic TRAMP-C2; murine, non-metastatic Myc-CaP; and human, non-metastatic 22rv1. The effects of DFP were evaluated at different cellular levels: cell culture proliferation and migration; metabolism of live cells (time-course multi-nuclear magnetic resonance spectroscopy cell perfusion studies, with 1-(13) C-glucose, and extracellular flux analysis); and expression (Western blot) and activity of mitochondrial aconitase, an iron-dependent enzyme...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272792/non-water-suppressed-short-echo-time-magnetic-resonance-spectroscopic-imaging-using-a-concentric-ring-k-space-trajectory
#15
Uzay E Emir, Brian Burns, Mark Chiew, Peter Jezzard, M Albert Thomas
Water-suppressed MRS acquisition techniques have been the standard MRS approach used in research and for clinical scanning to date. The acquisition of a non-water-suppressed MRS spectrum is used for artefact correction, reconstruction of phased-array coil data and metabolite quantification. Here, a two-scan metabolite-cycling magnetic resonance spectroscopic imaging (MRSI) scheme that does not use water suppression is demonstrated and evaluated. Specifically, the feasibility of acquiring and quantifying short-echo (TE  = 14 ms), two-dimensional stimulated echo acquisition mode (STEAM) MRSI spectra in the motor cortex is demonstrated on a 3 T MRI system...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272785/cest-imaging-of-fast-exchanging-amine-pools-with-corrections-for-competing-effects-at-9-4%C3%A2-t
#16
Xiao-Yong Zhang, Feng Wang, Hua Li, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
Chemical exchange saturation transfer (CEST) imaging of fast exchanging amine protons at 3 ppm offset from the water resonant frequency is of practical interest, but quantification of fast exchanging pools by CEST is challenging. To effectively saturate fast exchanging protons, high irradiation powers need to be applied, but these may cause significant direct water saturation as well as non-specific semi-solid magnetization transfer (MT) effects, and thus decrease the specificity of the measured signal. In addition, the CEST signal may depend on the water longitudinal relaxation time (T1w ), which likely varies between tissues and with pathology, further reducing specificity...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272771/sensitivity-of-diffusion-mri-to-perilesional-reactive-astrogliosis-in-focal-ischemia
#17
Rachel A Weber, Clifford H Chan, Xingju Nie, Emily Maggioncalda, Grace Valiulis, Abigail Lauer, Edward S Hui, Jens H Jensen, DeAnna L Adkins
Reactive astrogliosis is a response to injury in the central nervous system that plays an essential role in inflammation and tissue repair. It is characterized by hypertrophy of astrocytes, alterations in astrocyte gene expression and astrocyte proliferation. Reactive astrogliosis occurs in multiple neuropathologies, including stroke, traumatic brain injury and Alzheimer's disease, and it has been proposed as a possible source of the changes in diffusion magnetic resonance imaging (dMRI) metrics observed with these diseases...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272763/when-are-metabolic-ratios-superior-to-absolute-quantification-a-statistical-analysis
#18
Sarah E Hoch, Ivan I Kirov, Assaf Tal
Metabolite levels measured using magnetic resonance spectroscopy (MRS) are often expressed as ratios rather than absolute concentrations. However, the inter-subject variability of the denominator metabolite can introduce uncertainty into a metabolite ratio. In a clinical setting, there are no guidelines on whether ratios or absolute quantification should be used for a more accurate classification of normal versus abnormal results based on their statistical properties. In a research setting, the choice of one over the other can have significant implications on sample size, which must be factored in at the study design stage...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272761/accuracy-in-the-quantification-of-chemical-exchange-saturation-transfer-cest-and-relayed-nuclear-overhauser-enhancement-rnoe-saturation-transfer-effects
#19
Xiao-Yong Zhang, Feng Wang, Hua Li, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
Accurate quantification of chemical exchange saturation transfer (CEST) effects, including dipole-dipole mediated relayed nuclear Overhauser enhancement (rNOE) saturation transfer, is important for applications and studies of molecular concentration and transfer rate (and thereby pH or temperature). Although several quantification methods, such as Lorentzian difference (LD) analysis, multiple-pool Lorentzian fits, and the three-point method, have been extensively used in several preclinical and clinical applications, the accuracy of these methods has not been evaluated...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272754/hyperpolarized-%C3%AE-1-13-c-gluconolactone-as-a-probe-of-the-pentose-phosphate-pathway
#20
Karlos X Moreno, Crystal E Harrison, Matthew E Merritt, Zoltan Kovacs, Craig R Malloy, A Dean Sherry
The pentose phosphate pathway (PPP) is thought to be upregulated in trauma (to produce excess NADPH) and in cancer (to provide ribose for nucleotide biosynthesis), but simple methods for detecting changes in flux through this pathway are not available. MRI of hyperpolarized (13) C-enriched metabolites offers considerable potential as a rapid, non-invasive tool for detecting changes in metabolic fluxes. In this study, hyperpolarized δ-[1-(13) C]gluconolactone was used as a probe to detect flux through the oxidative portion of the pentose phosphate pathway (PPPox ) in isolated perfused mouse livers...
March 8, 2017: NMR in Biomedicine
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