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B1 mapping

Eleni Demetriou, Mohamed Tachrount, Moritz Zaiss, Karin Shmueli, Xavier Golay
PURPOSE: To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. METHODS: A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO-QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non-steady-state conditions, and off-resonance saturation is interleaved with the acquisition of images obtained through a Look-Locker type of acquisition...
March 5, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Tobias Würschum, Simon M Langer, C Friedrich H Longin, Matthew R Tucker, Willmar L Leiser
The broad adaptability of heading time has contributed to the global success of wheat in a diverse array of climatic conditions. Here, we investigated the genetic architecture underlying heading time in a large panel of 1,110 winter wheat cultivars of worldwide origin. Genome-wide association mapping, in combination with the analysis of major phenology loci, revealed a three-component system that facilitates the adaptation of heading time in winter wheat. The photoperiod sensitivity locus Ppd-D1 was found to account for almost half of the genotypic variance in this panel and can advance or delay heading by many days...
February 26, 2018: Plant, Cell & Environment
Fabian Kording, Bjoern P Schoennagel, Manuela Tavares de Sousa, Kai Fehrs, Gerhard Adam, Jin Yamamura, Christian Ruprecht
PURPOSE: Fetal cardiac MRI has the potential to play an important role in the assessment of fetal cardiac pathologies, but it is up to now not feasible due to a missing gating method. The purpose of this work was the evaluation of Doppler ultrasound (DUS) for external fetal cardiac gating with regard to compatibility, functionality, and reliability. Preliminary results were assessed performing fetal cardiac MRI. METHODS: An MRI conditional DUS device was developed to obtain a gating signal from the fetal heart...
February 21, 2018: Magnetic Resonance in Medical Sciences: MRMS
Niklaus Zoelch, Andreas Hock, Anke Henning
Quantification of magnetic resonance spectroscopy signals using the phantom replacement method requires an adequate correction of differences between the acquisition of the reference signal in the phantom and the measurement in vivo. Applying the principle of reciprocity, sensitivity differences can be corrected at low field strength by measuring the RF transmitter gain needed to obtain a certain flip angle in the measured volume. However, at higher field strength the transmit sensitivity may vary from the reception sensitivity, which leads to wrongly estimated concentrations...
February 21, 2018: NMR in Biomedicine
Filipa Mota, Constantina Fotinou, Rohini Rhana, A W Edith Chan, Tamas Yelland, Mohamed T Arooz, Andrew P O'Leary, Jennie Hutton, Paul Frankel, Ian Zachary, David Selwood, Snezana Djordjevic
Neuropilin-1 (NRP1) is a transmembrane co-receptor involved in binding interactions with variety of ligands and receptors, including receptor tyrosine kinases. Expression of NRP1 in several cancers correlates with cancer stages and poor prognosis. Thus, NRP1 has been considered a therapeutic target and is the focus of multiple drug discovery initiatives. Vascular endothelial growth factor (VEGF) binds to the b1 domain of NRP1 through interactions between the C-terminal arginine of VEGF and residues in the NRP1 binding site including Tyr297, Tyr353, Asp320, Ser346, and Thr349...
February 12, 2018: FEBS Journal
Viktor Pfaffenrot, Sascha Brunheim, Stefan H G Rietsch, Peter J Koopmans, Thomas M Ernst, Oliver Kraff, Stephan Orzada, Harald H Quick
PURPOSE: To design and evaluate an 8/15-channel transmit/receive (Tx/Rx) head-neck RF coil combination with region-specific B1+ shimming for whole-brain MRI with focus on improved functional MRI of the cerebellum at 7 T. METHODS: An 8-channel transceiver RF head coil was combined with a 7-channel receive-only array. The noise parameters and acceleration capabilities of this 8Tx/15Rx coil setup were compared with a commercially available 1Tx/32Rx RF head coil. Region-specific 8-channel B1+ shimming was applied when using the 8Tx/15Rx RF coil...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Srilata Ballu, Ramesh Itteboina, Sree Kanth Sivan, Vijjulatha Manga
Filamentous temperature-sensitive protein Z (FtsZ) is a protein encoded by the FtsZ gene that assembles into a Z-ring at the future site of the septum of bacterial cell division. Structurally, FtsZ is a homolog of eukaryotic tubulin but has low sequence similarity; this makes it possible to obtain FtsZ inhibitors without affecting the eukaryotic cell division. Computational studies were performed on a series of substituted 3-arylalkoxybenzamide derivatives reported as inhibitors of FtsZ activity in Staphylococcus aureus...
February 2018: Journal of Receptor and Signal Transduction Research
Adrian L Cabral, Mark C Jordan, Gary Larson, Daryl J Somers, D Gavin Humphreys, Curt A McCartney
Kernel morphology characteristics of wheat are complex and quantitatively inherited. A doubled haploid (DH) population of the cross RL4452/'AC Domain' was used to study the genetic basis of seed shape. Quantitative trait loci (QTL) analyses were conducted on a total of 18 traits: 14 grain shape traits, flour yield (Fyd), and three agronomic traits (Plant height [Plht], 1000 Grain weight [Gwt], Test weight [Twt]), using data from trial locations at Glenlea, Brandon, and Morden in Manitoba, Canada, between 1999 and 2004...
2018: PloS One
Nico Sollmann, Dominik Weidlich, Barbara Cervantes, Elisabeth Klupp, Carl Ganter, Hendrik Kooijman, Ernst J Rummeny, Claus Zimmer, Jan S Kirschke, Dimitrios C Karampinos
PURPOSE: Isotropic high-resolution three-dimensional (3D) magnetic resonance neurography (MRN) is increasingly used to depict even small and highly oblique nerves of the lumbosacral plexus (LSP). The present study introduces a T2 mapping sequence (T2-prepared 3D turbo spin echo) that is B1-insensitive and enables quantitative assessment of LSP nerves. METHODS: In this study 15 healthy subjects (mean age 28.5 ± 3.8 years) underwent 3 T MRN of the LSP area three times...
January 10, 2018: Clinical Neuroradiology
Ya-Jun Ma, Xing Lu, Michael Carl, Yanchun Zhu, Nikolaus M Szeverenyi, Graeme M Bydder, Eric Y Chang, Jiang Du
PURPOSE: To develop an accurate T1 measurement method for short T2 tissues using a combination of a 3-dimensional ultrashort echo time cones actual flip angle imaging technique and a variable repetition time technique (3D UTE-Cones AFI-VTR) on a clinical 3T scanner. METHODS: First, the longitudinal magnetization mapping function of the excitation pulse was obtained with the 3D UTE-Cones AFI method, which provided information about excitation efficiency and B1 inhomogeneity...
January 3, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Mingyan Li, Ewald Weber, Jin Jin, Thimo Hugger, Yasvir Tesiram, Peter Ullmann, Simon Stark, Miguel Fuentes, Sven Junge, Feng Liu, Stuart Crozier
The rotating radiofrequency coil (RRFC) has been developed recently as an alternative approach to multi-channel phased-array coils. The single-element RRFC avoids inter-channel coupling and allows a larger coil element with better B1 field penetration when compared with an array counterpart. However, dedicated image reconstruction algorithms require accurate estimation of temporally varying coil sensitivities to remove artefacts caused by coil rotation. Various methods have been developed to estimate unknown sensitivity profiles from a few experimentally measured sensitivity maps, but these methods become problematic when the RRFC is used as a transceiver coil...
December 27, 2017: NMR in Biomedicine
Riccardo Lattanzi, Bei Zhang, Florian Knoll, Jakob Assländer, Martijn A Cloos
PURPOSE: Magnetic Resonance Fingerprinting reconstructions can become computationally intractable with multiple transmit channels, if the B1+ phases are included in the dictionary. We describe a general method that allows to omit the transmit phases. We show that this enables straightforward implementation of dictionary compression to further reduce the problem dimensionality. METHODS: We merged the raw data of each RF source into a single k-space dataset, extracted the transceiver phases from the corresponding reconstructed images and used them to unwind the phase in each time frame...
December 23, 2017: Magnetic Resonance Imaging
Yukio Kaneko, Yoshihisa Soutome, Hideta Habara, Yoshitaka Bito, Hisaaki Ochi
B1+ inhomogeneity in the human body increases as the nuclear magnetic resonance (NMR) frequency increases. Various methods have thus been developed to reduce B1+ inhomogeneity, such as a dielectric pad, a coupling coil, parallel transmit, and radio-frequency (RF) shimming. However, B1+ inhomogeneity still remains in some cases of abdominal imaging. In this study, we developed a B1-control receive array coil (B-RAC). Unlike the conventional receive array coil, B-RAC reduces B1+ inhomogeneity by using additional PIN diodes to generate the inductive loop during the RF transmit period...
December 14, 2017: Journal of Magnetic Resonance
Ling-Yan Kong, Wei Zhang, Yue Zhou, Hai Xu, Hai-Bin Shi, Qing Feng, Xiao-Quan Xu, Tong-Fu Yu
OBJECTIVE: To investigate the value of apparent diffusion coefficients (ADCs) histogram analysis for assessing World Health Organization (WHO) pathological classification and Masaoka clinical stages of thymic epithelial tumours. METHODS: 37 patients with histologically confirmed thymic epithelial tumours were enrolled. ADC measurements were performed using hot-spot ROI (ADCHS-ROI ) and histogram-based approach. ADC histogram parameters included mean ADC (ADCmean ), median ADC (ADCmedian ), 10 and 90 percentile of ADC (ADC10 and ADC90 ), kurtosis and skewness...
January 10, 2018: British Journal of Radiology
Rosy Raman, Yu Qiu, Neil Coombes, Jie Song, Andrzej Kilian, Harsh Raman
Seed lost due to easy pod dehiscence at maturity (pod shatter) is a major problem in several members of Brassicaceae family. We investigated the level of pod shatter resistance in Ethiopian mustard (Brassica carinata) and identified quantitative trait loci (QTL) for targeted introgression of this trait in Ethiopian mustard and its close relatives of the genus Brassica. A set of 83 accessions of B. carinata, collected from the Australian Grains Genebank, was evaluated for pod shatter resistance based on pod rupture energy (RE)...
2017: Frontiers in Plant Science
Hiroyuki Kameda, Kohsuke Kudo, Tsuyoshi Matsuda, Taisuke Harada, Yuji Iwadate, Ikuko Uwano, Fumio Yamashita, Kunihiro Yoshioka, Makoto Sasaki, Hiroki Shirato
BACKGROUND: Respiration-induced phase shift affects B0 /B1 + mapping repeatability in parallel transmission (pTx) calibration for 7T brain MRI, but is improved by breath-holding (BH). However, BH cannot be applied during long scans. PURPOSE: To examine whether interleaved acquisition during calibration scanning could improve pTx repeatability and image homogeneity. STUDY TYPE: Prospective. SUBJECTS: Nine healthy subjects...
December 4, 2017: Journal of Magnetic Resonance Imaging: JMRI
Anirban Sengupta, Rakesh Kumar Gupta, Anup Singh
BACKGROUND: Dynamic-contrast-enhanced (DCE) MRI data acquired using gradient echo based sequences is affected by errors in flip angle (FA) due to transmit B1 inhomogeneity (B1 inh). The purpose of the study was to evaluate the effect of B1 inh on quantitative analysis of DCE-MRI data of human brain tumor patients and to evaluate the clinical significance of B1 inh correction of perfusion parameters (PPs) on tumor grading. METHODS: An MRI study was conducted on 35 glioma patients at 3T...
December 2, 2017: Journal of Translational Medicine
F Kording, C Ruprecht, B Schoennagel, K Fehrs, J Yamamura, G Adam, J Goebel, K Nassenstein, S Maderwald, H H Quick, O Kraff
PURPOSE: A prerequisite for cardiac MR (CMR) imaging is adequate synchronization of image acquisition with the cardiac cycle. Electrocardiogram triggering may be hampered by electromagnetic interferences at high field strength. The purpose of this work is to evaluate the feasibility of Doppler ultrasound triggering for CMR image synchronization at 7T ultra-high-field MRI. METHODS: A custom-built Doppler ultrasound (DUS) trigger device was developed. Magnetic resonance compatibility was evaluated using E- and H-field probes and flip angle maps prior to the study...
December 1, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Youngjun Mo, Tyson Howell, Hans Vasquez-Gross, Luis Alejandro de Haro, Jorge Dubcovsky, Stephen Pearce
Forward genetic screens of induced mutant plant populations are powerful tools to identify genes underlying phenotypes of interest. Using traditional techniques, mapping causative mutations from forward screens is a lengthy, multi-step process, requiring the identification of a broad genetic region followed by candidate gene sequencing to characterize the causal variant. Mapping by whole genome sequencing accelerates the identification of causal mutations by simultaneously defining a mapping region and providing information on the induced genetic variants...
November 29, 2017: Molecular Genetics and Genomics: MGG
Jie Wen, Alexander L Sukstanskii, Dmitriy A Yablonskiy
PURPOSE: To develop a phase-based B1 mapping technique accounting for the effects of imperfect RF spoiling and magnetization relaxation. THEORY AND METHODS: The technique is based on a multi-gradient-echo sequence with 2 successive orthogonal radiofrequency (RF) excitation pulses followed by the train of gradient echoes measurements. We have derived a theoretical expression relating the MR signal phase produced by the 2 successive RF pulses to the B1 field and B0 -related frequency shift...
November 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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