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https://www.readbyqxmd.com/read/28321915/acceleration-of-asl-based-time-resolved-mr-angiography-by-acquisition-of-control-and-labeled-images-in-the-same-shot-actress
#1
Yuriko Suzuki, Noriyuki Fujima, Tetsuo Ogino, James Alastair Meakin, Akira Suwa, Hiroyuki Sugimori, Marc Van Cauteren, Matthias J P van Osch
PURPOSE: Noncontrast 4D-MR-angiography (MRA) using arterial spin labeling (ASL) is beneficial because high spatial and temporal resolution can be achieved. However, ASL requires acquisition of labeled and control images for each phase. The purpose of this study is to present a new accelerated 4D-MRA approach that requires only a single control acquisition, achieving similar image quality in approximately half the scan time. METHODS: In a multi-phase Look-Locker sequence, the first phase was used as the control image and the labeling pulse was applied before the second phase...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28318404/magnetization-transfer-imaging-of-treatment-resistant-depression
#2
Zhiyun Jia, Wei Peng, Ziqi Chen, Huaiqiang Sun, Huawei Zhang, Weihong Kuang, Xiaoqi Huang, Su Lui, Qiyong Gong
Purpose To detect biophysical abnormalities in patients with postmedication treatment-resistant depression (TRD) with magnetization transfer imaging. Materials and Methods This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Participants included 69 patients with major depressive disorder (MDD) (30 with TRD; 39 with non-TRD) and 41 healthy control subjects. Age and sex were examined with one-way analysis of variance and χ(2) tests and were well matched among the three groups...
March 17, 2017: Radiology
https://www.readbyqxmd.com/read/28317074/probing-conformational-dynamics-in-biomolecules-via-chemical-exchange-saturation-transfer-a-primer
#3
Pramodh Valluruapalli, Ashok Sekhar, Tairan Yuwen, Lewis E Kay
Although Chemical Exchange Saturation Transfer (CEST) type NMR experiments have been used to study chemical exchange processes in molecules since the early 1960s, there has been renewed interest in the past several years in using this approach to study biomolecular conformational dynamics. The methodology is particularly powerful for the study of sparsely populated, transiently formed conformers that are recalcitrant to investigation using traditional biophysical tools, and it is complementary to relaxation dispersion and magnetization transfer experiments that have traditionally been used to study chemical exchange processes...
March 19, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28314207/a-pulse-sequence-for-singlet-to-heteronuclear-magnetization-transfer-s2hm
#4
Gabriele Stevanato, James Eills, Christian Bengs, Giuseppe Pileio
We have recently demonstrated, in the context of para-hydrogen induced polarization (PHIP), the conversion of hyperpolarized proton singlet order into heteronuclear magnetisation can be efficiently achieved via a new sequence named S2hM (Singlet to heteronuclear Magnetisation). In this paper we give a detailed theoretical description, supported by an experimental illustration, of S2hM. Theory and experiments on thermally polarized samples demonstrate the proposed method is robust to frequency offset mismatches and radiofrequency field inhomogeneities...
March 6, 2017: Journal of Magnetic Resonance
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
#5
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/28303591/-31-p-magnetization-transfer-magnetic-resonance-spectroscopy-assessing-the-activation-induced-change-in-cerebral-atp-metabolic-rates-at-3-t
#6
Chen Chen, Mary C Stephenson, Andrew Peters, Peter G Morris, Susan T Francis, Penny A Gowland
PURPOSE: In vivo (31) P magnetic resonance spectroscopy (MRS) magnetization transfer (MT) provides a direct measure of neuronal activity at the metabolic level. This work aims to use functional (31) P MRS-MT to investigate the change in cerebral adenosine triphosphate (ATP) metabolic rates in healthy adults upon repeated visual stimuli. METHODS: A magnetization saturation transfer sequence with narrowband selective saturation of γ-ATP was developed for (31) P MT experiments at 3 T...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28289599/quantitative-measures-of-walking-and-strength-provide-insight-into-brain-corticospinal-tract-pathology-in-multiple-sclerosis
#7
Nora E Fritz, Jennifer Keller, Peter A Calabresi, Kathleen M Zackowski
At least 85% of individuals with multiple sclerosis report walking dysfunction as their primary complaint. Walking and strength measures are common clinical measures to mark increasing disability or improvement with rehabilitation. Previous studies have shown an association between strength or walking ability and spinal cord MRI measures, and strength measures with brainstem corticospinal tract magnetization transfer ratio. However, the relationship between walking performance and brain corticospinal tract magnetization transfer imaging measures and the contribution of clinical measurements of walking and strength to the underlying integrity of the corticospinal tract has not been explored in multiple sclerosis...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28273886/quantitative-chemical-exchange-saturation-transfer-cest-mri-of-glioma-using-image-downsampling-expedited-adaptive-least-squares-ideal-fitting
#8
Iris Yuwen Zhou, Enfeng Wang, Jerry S Cheung, Xiaoan Zhang, Giulia Fulci, Phillip Zhe Sun
Chemical Exchange Saturation Transfer (CEST) MRI is sensitive to dilute metabolites with exchangeable protons, allowing tissue characterization in diseases such as acute stroke and tumor. CEST quantification using multi-pool Lorentzian fitting is challenging due to its strong dependence on image signal-to-noise ratio (SNR), initial values and boundaries. Herein we proposed an Image Downsampling Expedited Adaptive Least-squares (IDEAL) fitting algorithm that quantifies CEST images based on initial values from multi-pool Lorentzian fitting of iteratively less downsampled images until the original resolution...
December 2017: Scientific Reports
https://www.readbyqxmd.com/read/28272785/cest-imaging-of-fast-exchanging-amine-pools-with-corrections-for-competing-effects-at-9-4%C3%A2-t
#9
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/28268525/estimating-multimodal-brain-connectivity-in-multiple-sclerosis-an-exploratory-factor-analysis
#10
Matteo Mancini, Giovanni Giulietti, Barbara Spano, Marco Bozzali, Mara Cercignani, Silvia Conforto
Graph-theoretical approaches have become a popular way to model brain data collected using magnetic resonance imaging (MRI), both from the structural and the functional perspectives. In structural networks, tract-based mapping allows to model different aspects of brain structures by means of the specific characteristics of the different MRI modalities. However, there has been little effort to join the information carried by each modality and to understand what level of common variance is shown in these data...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28254453/structural-properties-of-the-human-corpus-callosum-multimodal-assessment-and-sex-differences
#11
L Björnholm, J Nikkinen, V Kiviniemi, T Nordström, S Niemelä, M Drakesmith, J C Evans, G B Pike, J Veijola, T Paus
A number of structural properties of white matter can be assessed in vivo using multimodal magnetic resonance imaging (MRI). We measured profiles of R1 and R2 relaxation rates, myelin water fraction (MWF) and diffusion tensor measures (fractional anisotropy [FA], mean diffusivity [MD]) across the mid-sagittal section of the corpus callosum in two samples of young individuals. In Part 1, we compared histology-derived axon diameter (Aboitiz et al., 1992) to MRI measures obtained in 402 young men (19.55 ± 0.84 years) recruited from the Avon Longitudinal Study on Parents and Children...
February 22, 2017: NeuroImage
https://www.readbyqxmd.com/read/28244138/b1-inhomogeneity-mitigation-in-cest-using-parallel-transmission
#12
Desmond H Y Tse, Nuno Andre da Silva, Benedikt A Poser, N Jon Shah
PURPOSE: In order to benefit from the increased spectral bandwidth at ultrahigh field (UHF), the use of parallel transmission (pTx) to mitigate flip-angle inhomogeneity in chemical exchange saturation transfer (CEST) imaging is investigated. THEORY AND METHODS: A pTx basis pulse is homogenised by magnitude least-squares (MLS) optimization and expanded to form a frequency-selective saturation pulse for CEST. The pTx saturation pulse was simulated with a three-pool Bloch-McConnell equation to evaluate the impact of pTx on CEST contrast...
February 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28242317/studying-brain-microstructure-with-magnetic-susceptibility-contrast-at-high-field
#13
Jeff H Duyn
A rapidly developing application of high field MRI is the study of brain anatomy and function with contrast based on the magnetic susceptibility of tissues. To study the subtle variations in susceptibility contrast between tissues and with changes in brain activity, dedicated scan techniques such as susceptibility-weighted MRI and blood-oxygen level dependent functional MRI have been developed. Particularly strong susceptibility contrast has been observed with systems that operate at 7T and above, and their recent widespread use has led to an improved understanding of contributing sources and mechanisms...
February 24, 2017: NeuroImage
https://www.readbyqxmd.com/read/28240402/in-vivo-detection-of-lateral-ventral-tier-nigral-degeneration-in-parkinson-s-disease
#14
Daniel E Huddleston, Jason Langley, Jan Sedlacik, Kai Boelmans, Stewart A Factor, Xiaoping P Hu
The objective of this study was to measure neuromelanin-sensitive MRI contrast changes in the lateral-ventral tier of substantia nigra pars compacta in Parkinson's disease (PD). Histopathological studies of PD have demonstrated both massive loss of melanized dopamine neurons and iron accumulation in the substantia nigra pars compacta. Neurodegeneration is most profound in the lateral-ventral tier of this structure. We have previously shown in both healthy controls and individuals with PD that neuromelanin-sensitive MRI and iron-sensitive MRI contrast regions in substantia nigra overlap...
February 27, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28229840/-magnetic-resonance-imaging-conversion-predictors-of-clinically-isolated-syndrome-to-multiple-sclerosis
#15
REVIEW
Sara Peixoto, Pedro Abreu
INTRODUCTION: Clinically isolated syndrome may be the first manifestation of multiple sclerosis, a chronic demyelinating disease of the central nervous system, and it is defined by a single clinical episode suggestive of demyelination. However, patients with this syndrome, even with long term follow up, may not develop new symptoms or demyelinating lesions that fulfils multiple sclerosis diagnostic criteria. We reviewed, in clinically isolated syndrome, what are the best magnetic resonance imaging findings that may predict its conversion to multiple sclerosis...
November 2016: Acta Médica Portuguesa
https://www.readbyqxmd.com/read/28226699/estimating-multimodal-brain-connectivity-in-multiple-sclerosis-an-exploratory-factor-analysis
#16
Matteo Mancini, Giovanni Giulietti, Barbara Spano, Marco Bozzali, Mara Cercignani, Silvia Conforto, Matteo Mancini, Giovanni Giulietti, Barbara Spano, Marco Bozzali, Mara Cercignani, Silvia Conforto, Giovanni Giulietti, Mara Cercignani, Silvia Conforto, Matteo Mancini, Barbara Spano, Marco Bozzali
Graph-theoretical approaches have become a popular way to model brain data collected using magnetic resonance imaging (MRI), both from the structural and the functional perspectives. In structural networks, tract-based mapping allows to model different aspects of brain structures by means of the specific characteristics of the different MRI modalities. However, there has been little effort to join the information carried by each modality and to understand what level of common variance is shown in these data...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28212272/design-of-novel-fbg-based-sensor-of-differential-pressure-with-magnetic-transfer
#17
Guohui Lyu, Guohang Che, Junqing Li, Xu Jiang, Keda Wang, Yueqiang Han, Laixu Gao
In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements...
February 15, 2017: Sensors
https://www.readbyqxmd.com/read/28195663/optimization-of-inhomogeneous-magnetization-transfer-ihmt-mri-contrast-for-preclinical-studies-using-dipolar-relaxation-time-t1d-filtering
#18
V H Prevost, O M Girard, S Mchinda, G Varma, D C Alsop, G Duhamel
A pulsed inhomogeneous magnetization transfer (ihMT)-prepared fast imaging sequence was implemented at 11.75 T for preclinical studies on mouse central nervous system. A strategy based on filtering the ihMT signal originating from short dipolar relaxation time (T1D ) components is proposed. It involves increasing the repetition time of consecutive radiofrequency (RF) pulses of the dual saturation and allows improved signal specificity for long T1D myelinated structures. Furthermore, frequency offset, power and timing saturation parameters were adjusted to optimize the ihMT sensitivity...
February 14, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28183276/peginterferon-beta-1a-improves-mri-measures-and-increases-the-proportion-of-patients-with-no-evidence-of-disease-activity-in-relapsing-remitting-multiple-sclerosis-2-year-results-from-the-advance-randomized-controlled-trial
#19
RANDOMIZED CONTROLLED TRIAL
Douglas L Arnold, Peter A Calabresi, Bernd C Kieseier, Shifang Liu, Xiaojun You, Damian Fiore, Serena Hung
BACKGROUND: Subcutaneous peginterferon beta-1a has previously been shown to reduce the number of T2-hyperintense and gadolinium-enhancing (Gd+) lesions over 2 years in patients with relapsing-remitting multiple sclerosis (RRMS), and to reduce T1-hypointense lesion formation and the proportion of patients showing evidence of disease activity, based on both clinical and radiological measures, compared with placebo over 1 year of treatment. The objectives of the current analyses were to evaluate T1 lesions and other magnetic resonance imaging (MRI) measures, including whole brain volume and magnetization transfer ratio (MTR) of normal appearing brain tissue (NABT), and the proportions of patients with no evidence of disease activity (NEDA), over 2 years...
February 10, 2017: BMC Neurology
https://www.readbyqxmd.com/read/28174533/reward-dependent-invigoration-relates-to-theta-oscillations-and-is-predicted-by-dopaminergic-midbrain-integrity-in-healthy-elderly
#20
Tineke K Steiger, Nico Bunzeck
Motivation can have invigorating effects on behavior via dopaminergic neuromodulation. While this relationship has mainly been established in theoretical models and studies in younger subjects, the impact of structural declines of the dopaminergic system during healthy aging remains unclear. To investigate this issue, we used electroencephalography (EEG) in healthy young and elderly humans in a reward-learning paradigm. Specifically, scene images were initially encoded by combining them with cues predicting monetary reward (high vs...
2017: Frontiers in Aging Neuroscience
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