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https://www.readbyqxmd.com/read/28777496/t2-mapping-with-magnetization-prepared-3d-tse-based-on-a-modified-bir-4%C3%A2-t2-preparation
#1
Dominik Weidlich, Sarah Schlaeger, Hendrik Kooijman, Peter Börnert, Jan S Kirschke, Ernst J Rummeny, Axel Haase, Dimitrios C Karampinos
The purpose of this work was to investigate the performance of the modified BIR-4 T2 preparation for T2 mapping and propose a method to remove T2 quantification errors in the presence of large B1 and B0 offsets. The theoretical investigation of the magnetization evolution during the T2 preparation in the presence of B1 and B0 offsets showed deviations from a mono-exponential T2 decay (two parameter fit). A three parameter fit was used to improve T2 accuracy. Furthermore, a two parameter fit with an additional saturation preparation scan was proposed to improve T2 accuracy and precision...
August 4, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28767360/software-toolbox-for-low-frequency-conductivity-and-current-density-imaging-using-mri
#2
Saurav Z K Sajib, Nitish Katoch, Hyung Joong Kim, Oh In Kwon, Eung Je Woo
OBJECTIVE: Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT...
July 27, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28635034/modular-transmit-receive-arrays-using-very-high-permittivity-dielectric-resonator-antennas
#3
Thomas P A O'Reilly, Thomas Ruytenberg, Andrew G Webb
PURPOSE: Dielectric resonator antenna (DRAs) are compact structures that exhibit low coupling between adjacent elements and therefore can be used as MRI transmit arrays. In this study, we use very high permittivity materials to construct modular flexible transceive arrays of a variable numbers of elements for operation at 7T. METHODS: DRAs were constructed using rectangular blocks of ceramic (lead zirconate titanate, εr  = 1070) with the transverse electric (TE)01 mode tuned to 298 MHz...
June 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28632688/high-quality-3-dimensional-1h-magnetic-resonance-spectroscopic-imaging-of-the-prostate-without-endorectal-receive-coil-using-a-semi-laser-sequence
#4
Nassim Tayari, Isabell K Steinseifer, Kirsten M Selnæs, Tone F Bathen, Marnix C Maas, Arend Heerschap
OBJECTIVES: Inclusion of 3-dimensional H magnetic resonance spectroscopic imaging (3D-H-MRSI) in routine multiparametric MRI of the prostate requires good quality spectra and easy interpretable metabolite maps of the whole organ obtained without endorectal coil in clinically feasible acquisition times. We evaluated if a semi-LASER pulse sequence with gradient offset independent adiabaticity refocusing pulses (GOIA-sLASER) for volume selection can meet these requirements. MATERIALS AND METHODS: Thirteen patients with suspicion of prostate cancer and 1 patient known to have prostate cancer were examined at 3 T with a multichannel body-receive coil...
June 19, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/28602814/quantitative-in-vivo-t2-mapping-using-fast-spin-echo-techniques-a-linear-correction-procedure
#5
Ulrike Nöth, Manoj Shrestha, Jan-Rüdiger Schüre, Ralf Deichmann
A method is presented for correcting the effects of stimulated and indirect echoes on quantitative T2 mapping data acquired with multiple spin echo techniques, such as turbo spin echo. In contrast to similar correction techniques proposed in the literature, the method does not require a priori knowledge of the radio frequency (RF) pulse profiles. In a first step, for the T2 mapping protocol under investigation, signal decay curves S(TE) are simulated for a range of different RF pulse profiles. The actual signal decay S(TE) is then measured on a phantom with known T2, so the approximate RF pulse profiles can be derived via comparison with the simulated decay curves...
June 9, 2017: NeuroImage
https://www.readbyqxmd.com/read/28590565/three-dimensional-mr-reconstruction-of-high-contrast-magnetic-susceptibility-by-the-variational-born-iterative-method-based-on-the-magnetic-field-volume-integral-equation
#6
Shengnan Li, Ronghan Hong, Na Liu, Jianhua Zhang, Lin Chen, Youyu Zhang, Zhiru Yu, Qing Huo Liu
PURPOSE: To provide high-quality and high-contrast magnetic susceptibility mapping, a 3D MR reconstruction method for magnetic susceptibility based on the magnetic field volume integral equation with the variational Born iterative method (VBIM) is developed. METHODS: Three-dimensional magnetic susceptibility is reconstructed from the positive rotating magnetic field component H1+ of the radiofrequency field acquired by B1 mapping. The stabilized biconjugate gradient fast Fourier transform (BCGS-FFT) method is implemented in the forward problem to solve for the magnetic field, and the conjugate gradient fast Fourier transform method is implemented in the inverse problem to reconstruct the magnetic susceptibility distribution...
June 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28556386/simple-modification-of-arm-position-improves-b1-and-signal-homogeneity-in-the-thoracolumbar-spine-at-3t
#7
Kinya Ishizaka, Kohsuke Kudo, Kuniaki Harada, Toru Shirai, Taro Fujiwara, Suzuko Aoike, Sayaka Takamori, Hiroki Shirato
PURPOSE: To evaluate the homogeneity of the radiofrequency magnetic field (B1(+) ) and signal intensity using different arm positions during 3T thoracolumbar spinal imaging. MATERIALS AND METHODS: Twenty volunteers were scanned with a four-channel radiofrequency (RF) transmit coil at 3T, with arms on the bed (conventional), arms elevated by 100 mm (arm lift), or with the arms-up position (elevated arm). Axial B1(+) maps and sagittal T1 -weighted image (T1 WI)-performed RF shimming were obtained for each arm position...
May 26, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28508476/magnetic-resonance-electrical-properties-tomography-for-small-anomalies-using-boundary-conditions-a-simulation-study
#8
Joonsung Lee, Narae Choi, Jin Keun Seo, Dong-Hyun Kim
PURPOSE: Magnetic Resonance Electrical Property Tomography (MREPT) is an emerging imaging modality using measured B1 maps from Magnetic Resonance Imaging (MRI) to measure a distribution of electric conductivity and permittivity of the subject at the Larmor frequency. Conventional MREPT approachesat single transmit channel system using the Helmholtz equation rely on an assumption that conductivity and permittivity of the subject are locally homogeneous. For small tissue structures and tissue boundaries, in which the assumption of locally homogeneous conductivity and permittivity does not hold, the reconstructed conductivity values deviated from the actual values, so called "Boundary Artifacts"...
May 16, 2017: Medical Physics
https://www.readbyqxmd.com/read/28465440/high-density-lipoprotein-receptor-scarb1-is-required-for-carotenoid-coloration-in-birds
#9
Matthew B Toomey, Ricardo J Lopes, Pedro M Araújo, James D Johnson, Małgorzata A Gazda, Sandra Afonso, Paulo G Mota, Rebecca E Koch, Geoffrey E Hill, Joseph C Corbo, Miguel Carneiro
Yellow, orange, and red coloration is a fundamental aspect of avian diversity and serves as an important signal in mate choice and aggressive interactions. This coloration is often produced through the deposition of diet-derived carotenoid pigments, yet the mechanisms of carotenoid uptake and transport are not well-understood. The white recessive breed of the common canary (Serinus canaria), which carries an autosomal recessive mutation that renders its plumage pure white, provides a unique opportunity to investigate mechanisms of carotenoid coloration...
May 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28437453/three-dominant-awnless-genes-in-common-wheat-fine-mapping-interaction-and-contribution-to-diversity-in-awn-shape-and-length
#10
Motohiro Yoshioka, Julio C M Iehisa, Ryoko Ohno, Tatsuro Kimura, Hiroyuki Enoki, Satoru Nishimura, Shuhei Nasuda, Shigeo Takumi
The awn is a long needle-like structure formed at the tip of the lemma in the florets of some grass species. It plays a role in seed dispersal and protection against animals, and can contribute to the photosynthetic activity of spikes. Three main dominant inhibitors of awn development (Hd, B1 and B2) are known in hexaploid wheat, but the causal genes have not been cloned yet and a genetic association with awn length diversity has been found only for the B1 allele. To analyze the prevalence of these three awning inhibitors, we attempted to predict the genotypes of 189 hexaploid wheat varieties collected worldwide using markers tightly linked to these loci...
2017: PloS One
https://www.readbyqxmd.com/read/28431009/artefact-free-late-gadolinium-enhancement-imaging-in-patients-with-implanted-cardiac-devices-using-a-modified-broadband-sequence-current-strategies-and-results-from-a-real-world-patient-cohort
#11
Sebastian Hilbert, Alexander Weber, Kay Nehrke, Peter Börnert, Bernhard Schnackenburg, Sabrina Oebel, Ricardo Spampinato, Cathleen Rogge, Sergio Richter, Gerhard Hindricks, Ingo Paetsch, Cosima Jahnke
Aims: Cardiac magnetic resonance (CMR) imaging in patients with implanted cardiac devices is often limited by device-related imaging artefacts. Limitations can potentially be overcome by employing a broadband late gadolinium enhancement (LGE)-CMR imaging technique. The purpose of this study was to investigate the relationship between implanted cardiac devices and the optimal frequency offset on broadband LGE-CMR imaging to increase the artefact-free visibility of myocardial segments. Methods and results: A phantom study was performed to characterize magnetic field disturbances related to 15 different cardiac devices...
April 18, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28424353/constrained-release-of-lamina-associated-enhancers-and-genes-from-the-nuclear-envelope-during-t-cell-activation-facilitates-their-association-in-chromosome-compartments
#12
Michael I Robson, Jose I de Las Heras, Rafal Czapiewski, Aishwarya Sivakumar, Alastair R W Kerr, Eric C Schirmer
The 3D organization of the genome changes concomitantly with expression changes during hematopoiesis and immune activation. Studies have focused either on lamina-associated domains (LADs) or on topologically associated domains (TADs), defined by preferential local chromatin interactions, and chromosome compartments, defined as higher-order interactions between TADs sharing functionally similar states. However, few studies have investigated how these affect one another. To address this, we mapped LADs using Lamin B1-DamID during Jurkat T-cell activation, finding significant genome reorganization at the nuclear periphery dominated by release of loci frequently important for T-cell function...
July 2017: Genome Research
https://www.readbyqxmd.com/read/28409357/diffusion-weighted-mri-to-assess-response-to-chemoradiotherapy-in-rectal-cancer-main-interpretation-pitfalls-and-their-use-for-teaching
#13
Doenja M J Lambregts, Miriam M van Heeswijk, Andrea Delli Pizzi, Saskia G C van Elderen, Luisa Andrade, Nicky H G M Peters, Peter A M Kint, Margreet Osinga-de Jong, Shandra Bipat, Rik Ooms, Max J Lahaye, Monique Maas, Geerard L Beets, Frans C H Bakers, Regina G H Beets-Tan
OBJECTIVES: To establish the most common image interpretation pitfalls for non-expert readers using diffusion-weighted imaging (DWI) to assess response to chemoradiotherapy in patients with rectal cancer and to explore the use of these pitfalls in an expert teaching setting. METHODS: Two independent non-expert readers (R1 and R2) scored the restaging DW MRI scans (b1,000 DWI, in conjunction with ADC maps and T2-W MRI scans for anatomical reference) in 100 patients for the likelihood of a complete response versus residual tumour using a five-point confidence score...
April 13, 2017: European Radiology
https://www.readbyqxmd.com/read/28370494/tailored-spiral-in-out-spectral-spatial-water-suppression-pulses-for-magnetic-resonance-spectroscopic-imaging
#14
Jun Ma, Carrie Wismans, Zhipeng Cao, Dennis W J Klomp, Jannie P Wijnen, William A Grissom
PURPOSE: To develop short water suppression sequences for 7 T magnetic resonance spectroscopic imaging, with mitigation of subject-specific transmit RF field ( B1+) inhomogeneity. METHODS: Patient-tailored spiral in-out spectral-spatial saturation pulses were designed for a three-pulse WET water suppression sequence. The pulses' identical spatial subpulses were designed using patient-specific B1+ maps and a spiral in-out excitation k-space trajectory. The subpulse train was weighted by a spectral envelope that was root-flipped to minimize peak RF demand...
March 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28349596/b1-sensitivity-analysis-of-quantitative-magnetization-transfer-imaging
#15
Mathieu Boudreau, Nikola Stikov, G Bruce Pike
PURPOSE: To evaluate the sensitivity of quantitative magnetization transfer (qMT) fitted parameters to B1 inaccuracies, focusing on the difference between two categories of T1 mapping techniques: B1 -independent and B1 -dependent. METHODS: The B1 -sensitivity of qMT was investigated and compared using two T1 measurement methods: inversion recovery (IR) (B1 -independent) and variable flip angle (VFA), B1 -dependent). The study was separated into four stages: 1) numerical simulations, 2) sensitivity analysis of the Z-spectra, 3) healthy subjects at 3T, and 4) comparison using three different B1 imaging techniques...
March 27, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28346710/the-arabidopsis-thiamin-deficient-mutant-pale-green1-lacks-thiamin-monophosphate-phosphatase-of-the-vitamin-b1-biosynthesis-pathway
#16
Wei-Yu Hsieh, Jo-Chien Liao, Hsin-Tzu Wang, Tzu-Huan Hung, Ching-Chih Tseng, Tsui-Yun Chung, Ming-Hsiun Hsieh
Thiamin diphosphate (TPP, vitamin B1 ) is an essential coenzyme present in all organisms. Animals obtain TPP from their diets, but plants synthesize TPPde novo. We isolated and characterized an Arabidopsis pale green1 (pale1) mutant that contained higher concentrations of thiamin monophosphate (TMP) and less thiamin and TPP than the wild type. Supplementation with thiamin, but not the thiazole and pyrimidine precursors, rescued the mutant phenotype, indicating that the pale1 mutant is a thiamin-deficient mutant...
March 27, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28343894/-1-9-n%C3%AE-c-crourorb-a1-isolated-from-croton-urucurana-latex-induces-g2-m-cell-cycle-arrest-and-apoptosis-in-human-hepatocarcinoma-cells
#17
Priscila de Matos Cândido-Bacani, Frédéric Ezan, Patrícia de Oliveira Figueiredo, Maria de Fátima Cepa Matos, Fernanda Rodrigues Garcez, Walmir Silva Garcez, Georges Baffet
[1-9-NαC]-crourorb A1 is a cyclic peptide isolated from Croton urucurana Baillon latex, found in midwestern Brazil, that has been shown to exert cytotoxic effects against a panel of cancer cell lines. However, the underlying mechanisms responsible for the crourorb A1-induced cytotoxicity in cancer cells remain unknown. In this study, the effects of crourorb A1 on the viability, apoptosis, cell cycle and migration of Huh-7 (human hepatocarcinoma) cells were investigated. We evaluated the viability of Huh-7 cells treated with crourorb A1 in 2D and 3D collagen cultures and found that cells in 3D culture exhibited increased resistance to crourorb A1 compared to cells in 2D culture (IC50: 62μg/ml versus 35...
May 5, 2017: Toxicology Letters
https://www.readbyqxmd.com/read/28336427/high-resolution-anatomical-and-quantitative-mri-of-the-entire-human-occipital-lobe-ex-vivo-at-9-4t
#18
S Sengupta, F J Fritz, R L Harms, S Hildebrand, D H Y Tse, B A Poser, R Goebel, A Roebroeck
Several magnetic resonance imaging (MRI) contrasts are sensitive to myelin content in gray matter in vivo which has ignited ambitions of MRI-based in vivo cortical histology. Ultra-high field (UHF) MRI, at fields of 7T and beyond, is crucial to provide the resolution and contrast needed to sample contrasts over the depth of the cortex and get closer to layer resolved imaging. Ex vivo MRI of human post mortem samples is an important stepping stone to investigate MRI contrast in the cortex, validate it against histology techniques applied in situ to the same tissue, and investigate the resolutions needed to translate ex vivo findings to in vivo UHF MRI...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28304246/a-mouse-model-for-human-unstable-hemoglobin-santa-ana
#19
Samantha I Miyashiro, Silvia M G Massironi, Claudia M C Mori, Carolina C Cruz, Mitika K Hagiwara, Paulo C Maiorka
In the present study, we described the phenotype, histologic morphology, and molecular etiology of a mouse model of unstable hemoglobin Santa Ana. Hematologic evaluation of anemic mice (Anem/+) discovered after N-ethyl-N-nitrosourea mutagenesis revealed moderate anemia with intense reticulocytosis and polychromasia, followed by anisocytosis, macrocytosis, hypochromia, and intraerythrocytic inclusion and Heinz bodies. The mice also demonstrated hemoglobinuria, bilirubinemia, and erythrocytic populations with differing resistance to osmotic lysis...
December 1, 2016: Comparative Medicine
https://www.readbyqxmd.com/read/28301086/b1-mapping-for-bias-correction-in-quantitative-t1-imaging-of-the-brain-at-3t-using-standard-pulse-sequences
#20
Mathieu Boudreau, Christine L Tardif, Nikola Stikov, John G Sled, Wayne Lee, G Bruce Pike
PURPOSE: B1 mapping is important for many quantitative imaging protocols, particularly those that include whole-brain T1 mapping using the variable flip angle (VFA) technique. However, B1 mapping sequences are not typically available on many magnetic resonance imaging (MRI) scanners. The aim of this work was to demonstrate that B1 mapping implemented using standard scanner product pulse sequences can produce B1 (and VFA T1 ) maps comparable in quality and acquisition time to advanced techniques...
March 16, 2017: Journal of Magnetic Resonance Imaging: JMRI
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