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https://www.readbyqxmd.com/read/28196133/b1-insensitive-t2-mapping-of-healthy-thigh-muscles-using-a-t2-prepared-3d-tse-sequence
#1
Elisabeth Klupp, Dominik Weidlich, Sarah Schlaeger, Thomas Baum, Barbara Cervantes, Marcus Deschauer, Hendrik Kooijman, Ernst J Rummeny, Claus Zimmer, Jan S Kirschke, Dimitrios C Karampinos
PURPOSE: To propose a T2-prepared 3D turbo spin echo (T2prep 3D TSE) sequence for B1-insensitive skeletal muscle T2 mapping and compare its performance with 2D and 3D multi-echo spin echo (MESE) for T2 mapping in thigh muscles of healthy subjects. METHODS: The performance of 2D MESE, 3D MESE and the proposed T2prep 3D TSE in the presence of transmit B1 and B0 inhomogeneities was first simulated. The thigh muscles of ten young and healthy subjects were then scanned on a 3 T system and T2 mapping was performed using the three sequences...
2017: PloS One
https://www.readbyqxmd.com/read/28167399/adapted-mr-velocimetry-of-slow-liquid-flow-in-porous-media
#2
Li Huang, Gerd Mikolajczyk, Ekkehard Küstermann, Michaela Wilhelm, Stefan Odenbach, Wolfgang Dreher
MR velocimetry of liquid flow in opaque porous filters may play an important role in better understanding the mechanisms of deep bed filtration. With this knowledge, the efficiency of separating the suspended solid particles from the vertically flowing liquid can be improved, and thus a wide range of industrial applications such as wastewater treatment and desalination can be optimized. However, MR velocimetry is challenging for such studies due to the low velocities, the severe B0 inhomogeneity in porous structures, and the demand for high spatial resolution and an appropriate total measurement time during which the particle deposition will change velocities only marginally...
January 27, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28166977/caloric-restriction-and-igf-i-administration-promote-rabbit-fecundity-possible-interrelationships-and-mechanisms-of-action
#3
Alexander V Sirotkin, Iveta Koničková Florkovičová, Olga Østrup Švarcová, Jan Rafay, Jozef Laurincik, Abdel Halim Harrath
The aim of these in vivo and in vitro studies was to examine the influence of caloric restriction (CR), and the administration of insulin-like growth factor (IGF-I), on rabbit fecundity and to understand the interrelationships between CR and IGF-I, as well as the endocrine and intracellular mechanisms of their effects. Female rabbits were subjected to 50% CR, injections of IGF-I (20 μg/animal/day) and a combination of the two for 10 d before and 2 d after ovulation induced by 25 IU PMSG and 0.25 IU hCG...
March 1, 2017: Theriogenology
https://www.readbyqxmd.com/read/28163582/mapping-a-qtl-conferring-resistance-to-fusarium-head-blight-on-chromosome-1b-in-winter-wheat-triticum-aestivum-l
#4
Zenta Nishio, Chihiro Onoe, Miwako Ito, Tadashi Tabiki, Koichi Nagasawa, Hideho Miura
Fusarium head blight (FHB) is one of the most devastating diseases of wheat (Triticum aestivum L.), and the development of cultivars with FHB resistance is the most effective way to control the disease. Yumechikara is a Japanese hard red winter wheat cultivar that shows moderate resistance to FHB with superior bread-making quality. To identify quantitative trait loci (QTLs) for FHB resistance in Yumechikara, we evaluated doubled haploid lines derived from a cross between Yumechikara and a moderate susceptible cultivar, Kitahonami, for FHB resistance in a 5-year field trial, and we analyzed polymorphic molecular markers between the parents...
December 2016: Breeding Science
https://www.readbyqxmd.com/read/28158253/qtls-associated-with-agronomic-traits-in-the-attila-%C3%A3-cdc-go-spring-wheat-population-evaluated-under-conventional-management
#5
Jun Zou, Kassa Semagn, Muhammad Iqbal, Hua Chen, Mohammad Asif, Amidou N'Diaye, Alireza Navabi, Enid Perez-Lara, Curtis Pozniak, Rong-Cai Yang, Harpinder Randhawa, Dean Spaner
Recently, we investigated the effect of the wheat 90K single nucleotide polymorphic (SNP) array and three gene-specific (Ppd-D1, Vrn-A1 and Rht-B1) markers on quantitative trait loci (QTL) detection in a recombinant inbred lines (RILs) population derived from a cross between two spring wheat (Triticum aestivum L.) cultivars, 'Attila' and 'CDC Go', and evaluated for eight agronomic traits at three environments under organic management. The objectives of the present study were to investigate the effect of conventional management on QTL detection in the same mapping population using the same set of markers as the organic management and compare the results with organic management...
2017: PloS One
https://www.readbyqxmd.com/read/28113801/simultaneous-quantitative-imaging-of-electrical-properties-and-proton-density-from-b1-maps-using-mri
#6
Jiaen Liu, Pierre-Francois Van de Moortele, Xiaotong Zhang, Yicun Wang, Bin He
Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI)...
March 29, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28113215/modeling-endovascular-mri-coil-coupling-with-transmit-rf-excitation
#7
Madhav Venkateswaran, Orhan Unal, Samuel Hurley, Alexey Samsonov, Peng Wang, Sean Fain, Krishna Kurpad
OBJECTIVE: To model inductive coupling of endovascular coils with transmit RF excitation for selecting coils for MRI-guided interventions. METHODS: Independent and computationally efficient FEM models are developed for the endovascular coil, cable, transmit excitation and imaging domain. Electromagnetic and circuit solvers are coupled to simulate net B1+ fields and induced currents and voltages. Our models are validated using the Bloch Siegert B1+ mapping sequence for a series-tuned multimode coil, capable of tracking, wireless visualization and high resolution endovascular imaging...
March 4, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28112824/in-vivo-imaging-of-electrical-properties-of-an-animal-tumor-model-with-an-8-channel-transceiver-array-at-7%C3%A2-t-using-electrical-properties-tomography
#8
Jiaen Liu, Qi Shao, Yicun Wang, Gregor Adriany, John Bischof, Pierre-Francois Van de Moortele, Bin He
PURPOSE: To develop and evaluate a technique for imaging electrical properties ((EPs), conductivity and permittivity) of an animal tumor model in vivo using MRI. METHODS: Electrical properties were reconstructed from the calculated EP gradient, which was derived using two sets of measured transmit B1 magnitude and relative phase maps with the sample and radiofrequency (RF) coil oriented in the positive and negative z-directions, respectively. An eight-channel transceiver microstrip array RF coil fitting the size of the animal was developed for generating and mapping B1 fields to reconstruct EPs...
January 23, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28109190/qtl-mapping-and-candidate-genes-for-resistance-to-fusarium-ear-rot-and-fumonisin-contamination-in-maize
#9
Valentina Maschietto, Cinzia Colombi, Raul Pirona, Giorgio Pea, Francesco Strozzi, Adriano Marocco, Laura Rossini, Alessandra Lanubile
BACKGROUND: Fusarium verticillioides is a common maize pathogen causing ear rot (FER) and contamination of the grains with the fumonisin B1 (FB1) mycotoxin. Resistance to FER and FB1 contamination are quantitative traits, affected by environmental conditions, and completely resistant maize genotypes to the pathogen are so far unknown. In order to uncover genomic regions associated to reduced FER and FB1 contamination and identify molecular markers for assisted selection, an F2:3 population of 188 progenies was developed crossing CO441 (resistant) and CO354 (susceptible) genotypes...
January 21, 2017: BMC Plant Biology
https://www.readbyqxmd.com/read/28103666/molecular-dynamics-simulations-reveal-isoform-specific-contact-dynamics-between-the-plexin-rho-gtpase-binding-domain-rbd-and-small-rho-gtpases-rac1-and-rnd1
#10
Liqun Zhang, Matthias Buck
The Plexin family of transmembrane receptors are unique in that their intracellular region interacts directly with small GTPases of the Rho family. The Rho GTPase Binding Domain of plexin (RBD) -that is responsible for these interactions- can bind with Rac1 as well as Rnd1 GTPases. GTPase complexes have been crystallized with the RBDs of plexinA1, -A2 and -B1. The protein association is thought to elicit different functional responses, possibly in a GTPase/plexin isoform specific manner. In this project, we investigated complexes between several RBD and Rac1/Rnd1 GTPases using multi-microsecond length all atom molecular dynamics simulations, also with reference to the free forms of the RBDs and GTPases...
January 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28102957/rf-safety-assessment-of-a-bilateral-four-channel-transmit-receive-7-tesla-breast-coil-sar-versus-tissue-temperature-limits
#11
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
PURPOSE: The purpose of this work was to perform an RF safety evaluation for a bilateral four-channel transmit/receive breast coil and to determine the maximum permissible input power for which RF exposure of the subject stays within recommended limits. The safety evaluation was done based on SAR as well as on temperature simulations. In comparison to SAR, temperature is more directly correlated with tissue damage, which allows a more precise safety assessment. The temperature simulations were performed by applying three different blood perfusion models as well as two different ambient temperatures...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28074530/slice-profile-and-b1-corrections-in-2d-magnetic-resonance-fingerprinting
#12
Dan Ma, Simone Coppo, Yong Chen, Debra F McGivney, Yun Jiang, Shivani Pahwa, Vikas Gulani, Mark A Griswold
PURPOSE: The goal of this study is to characterize and improve the accuracy of 2D magnetic resonance fingerprinting (MRF) scans in the presence of slice profile (SP) and B1 imperfections, which are two main factors that affect quantitative results in MRF. METHODS: The SP and B1 imperfections are characterized and corrected separately. The SP effect is corrected by simulating the radiofrequency pulse in the dictionary, and the B1 is corrected by acquiring a B1 map using the Bloch-Siegert method before each scan...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28047962/tu-h-206-03-characterizing-b1-inhomogeneities-in-dce-mri
#13
H Gach, N Mason
PURPOSE: Dynamic Contrast Enhanced (DCE) MRI is a valuable technique for measuring perfusion and permeability characteristics of tumors. Exogenous contrast concentrations are calculated based on changes in T1 measured using fast 3D gradient echo (FLASH) sequences. However, the slab selective pulses used in 3D MRI may result in B1 inhomogeneities across the volume of interest that can lead to errors in T1 and thus the estimated gadolinium concentration. We compared three FLASH DCE sequences (GRE, TWIST, and VIBE) to determine their signal homogeneity across slices and the accuracy in calculating T1 using acquisitions with variable flip angles...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047863/tu-h-206-06-b1-inhomogeneity-correction-for-measuring-t1-from-dce-mri
#14
H Gach, N Mason, H Wang, C Tsien, T Benzinger, C Robinson
PURPOSE: 3D MRI sequences typically used in DCE MRI suffer from B1 inhomogeneities associated with the slab-selective RF pulse. B1 inhomogeneities affect the calculation of tissue T1 often used to solve the two-compartment model. Previously, the inhomogeneities were corrected based on Bloch equation simulations of the RF pulse. However, the RF pulse specification may not be readily available or the simulation may not represent the actual scan conditions. The objective of this work was to directly measure B1 inhomogeneities and apply an inhomogeneity correction to minimize quantification errors in T1 fitting...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047295/tu-h-206-04-an-effective-homomorphic-unsharp-mask-filtering-method-to-correct-intensity-inhomogeneity-in-daily-treatment-mr-images
#15
D Yang, H Gach, H Li, S Mutic
PURPOSE: The daily treatment MRIs acquired on MR-IGRT systems, like diagnostic MRIs, suffer from intensity inhomogeneity issue, associated with B1 and B0 inhomogeneities. An improved homomorphic unsharp mask (HUM) filtering method, automatic and robust body segmentation, and imaging field-of-view (FOV) detection methods were developed to compute the multiplicative slow-varying correction field and correct the intensity inhomogeneity. The goal is to improve and normalize the voxel intensity so that the images could be processed more accurately by quantitative methods (e...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28046531/tu-h-206-08-quantitative-impact-of-biliary-stent-artefacts-on-mr-images
#16
O Gurney-Champion, T Bruins Slot, E Lens, A van der Horst, R Klaassen, H van Laarhoven, J van Hooft, A Nederveen, A Bel
PURPOSE: Biliary stents may cause artifacts in MR-images. These artifacts are caused by differences in susceptibility (artifact-1), eddy currents during read-out (artifact-2) and eddy currents due to the excitation pulse (artifact-3), which all are MRI sequence-dependent. In this study, we investigated and quantified the magnitude of these artifacts as a function of the distance from biliary stents, using a sequence-independent approach where possible. METHODS: Eight phantoms were made containing different commercial biliary stents made of nitinol, platinol, stainless steel or polyethylene...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28044146/bloch-siegert-b1-mapping-improves-accuracy-and-precision-of-longitudinal-relaxation-measurements-in-the-breast-at-3-t
#17
Jennifer G Whisenant, Richard D Dortch, William Grissom, Hakmook Kang, Lori R Arlinghaus, Thomas E Yankeelov
Variable flip angle (VFA) sequences are a popular method of calculating T1 values, which are required in a quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). B1 inhomogeneities are substantial in the breast at 3 T, and these errors negatively impact the accuracy of the VFA approach, thus leading to large errors in the DCE-MRI parameters that could limit clinical adoption of the technique. This study evaluated the ability of Bloch-Siegert B1 mapping to improve the accuracy and precision of VFA-derived T1 measurements in the breast...
December 2016: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28011252/construction-and-modeling-of-a-reconfigurable-mri-coil-for-lowering-sar-in-patients-with-deep-brain-stimulation-implants
#18
Laleh Golestanirad, Maria Ida Iacono, Boris Keil, Leonardo M Angelone, Giorgio Bonmassar, Michael D Fox, Todd Herrington, Elfar Adalsteinsson, Cristen LaPierre, Azma Mareyam, Lawrence L Wald
Post-operative MRI of patients with deep brain simulation (DBS) implants is useful to assess complications and diagnose comorbidities, however more than one third of medical centers do not perform MRIs on this patient population due to stringent safety restrictions and liability risks. A new system of reconfigurable magnetic resonance imaging head coil composed of a rotatable linearly-polarized birdcage transmitter and a close-fitting 32-channel receive array is presented for low-SAR imaging of patients with DBS implants...
February 15, 2017: NeuroImage
https://www.readbyqxmd.com/read/28005010/simultaneous-quantitative-imaging-of-electrical-properties-and-proton-density-from-b1-maps-using-mri
#19
Jiaen Liu, Pierre-Francois Van de Moortele, Xiaotong Zhang, Yicun Wang, Bin He
Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI)...
September 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27988808/inheritance-and-quantitative-trail-loci-mapping-of-adventitious-root-numbers-in-cucumber-seedlings-under-waterlogging-conditions
#20
Xuewen Xu, Jing Ji, Qiang Xu, Xiaohua Qi, Xuehao Chen
The hypocotyl-derived adventitious root (AR) is an important morphological acclimation to waterlogging stress; however, its genetic basis has not been adequately understood. In the present study, a mixed major gene plus polygene inheritance model was used to analyze AR numbers (ARN) 7 days after waterlogging treatment in six generations (P1, P2, F1, B1, B2, and F2), using cucumber waterlogging tolerant line Zaoer-N and sensitive Pepino as parents. The results showed that the genetic model D-4, mixed one negative dominance major gene and additive-dominance polygenes, is the best-fitting genetic model for waterlogging-triggered ARN phenotype...
December 17, 2016: Molecular Genetics and Genomics: MGG
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