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https://www.readbyqxmd.com/read/28435103/magnetization-transfer-contrast-and-chemical-exchange-saturation-transfer-mri-features-and-analysis-of-the-field-dependent-saturation-spectrum
#1
Peter C M van Zijl, Wilfred W Lam, Jiadi Xu, Linda Knutsson, Greg J Stanisz
Magnetization Transfer Contrast (MTC) and Chemical Exchange Saturation Transfer (CEST) experiments measure the transfer of magnetization from molecular protons to the solvent water protons, an effect that becomes apparent as an MRI signal loss ("saturation"). This allows molecular information to be accessed with the enhanced sensitivity of MRI. In analogy to Magnetic Resonance Spectroscopy (MRS), these saturation data are presented as a function of the chemical shift of participating proton groups, e.g. OH, NH, NH2, which is called a Z-spectrum...
April 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28428213/clinically-feasible-microstructural-mri-to-quantify-cervical-spinal-cord-tissue-injury-using-dti-mt-and-t2-weighted-imaging-assessment-of-normative-data-and-reliability
#2
A R Martin, B De Leener, J Cohen-Adad, D W Cadotte, S Kalsi-Ryan, S F Lange, L Tetreault, A Nouri, A Crawley, D J Mikulis, H Ginsberg, M G Fehlings
BACKGROUND AND PURPOSE: DTI, magnetization transfer, T2*-weighted imaging, and cross-sectional area can quantify aspects of spinal cord microstructure. However, clinical adoption remains elusive due to complex acquisitions, cumbersome analysis, limited reliability, and wide ranges of normal values. We propose a simple multiparametric protocol with automated analysis and report normative data, analysis of confounding variables, and reliability. MATERIALS AND METHODS: Forty healthy subjects underwent T2WI, DTI, magnetization transfer, and T2*WI at 3T in <35 minutes using standard hardware and pulse sequences...
April 20, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28428212/a-novel-mri-biomarker-of-spinal-cord-white-matter-injury-t2-weighted-white-matter-to-gray-matter-signal-intensity-ratio
#3
A R Martin, B De Leener, J Cohen-Adad, D W Cadotte, S Kalsi-Ryan, S F Lange, L Tetreault, A Nouri, A Crawley, D J Mikulis, H Ginsberg, M G Fehlings
BACKGROUND AND PURPOSE: T2*-weighted imaging provides sharp contrast between spinal cord GM and WM, allowing their segmentation and cross-sectional area measurement. Injured WM demonstrates T2*WI hyperintensity but requires normalization for quantitative use. We introduce T2*WI WM/GM signal-intensity ratio and compare it against cross-sectional area, the DTI metric fractional anisotropy, and magnetization transfer ratio in degenerative cervical myelopathy. MATERIALS AND METHODS: Fifty-eight patients with degenerative cervical myelopathy and 40 healthy subjects underwent 3T MR imaging, covering C1-C7...
April 20, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28408961/the-usefulness-of-diagnostic-imaging-for-the-assessment-of-pain-symptoms-in-temporomandibular-disorders
#4
REVIEW
Shigeaki Suenaga, Kunihiro Nagayama, Taisuke Nagasawa, Hiroko Indo, Hideyuki J Majima
The causes of pain symptoms in the temporomandibular joint (TMJ) and masticatory muscle (MM) regions may not be determined by clinical examination alone. In this review, we document that pain symptoms of the TMJ and MM regions in patients with temporomandibular disorders (TMDs) are associated with computed tomography and magnetic resonance (MR) findings of internal derangement, joint effusion, osteoarthritis, and bone marrow edema. However, it is emphasized that these imaging findings must not be regarded as the unique and dominant factors in defining TMJ pain...
November 2016: Japanese Dental Science Review
https://www.readbyqxmd.com/read/28407330/diffusion-weighted-and-magnetization-transfer-imaging-in-testicular-spermatogenic-function-evaluation-preliminary-results
#5
Huanjun Wang, Jian Guan, Jinhua Lin, Zhongwei Zhang, Shurong Li, Yan Guo, Huasong Cai
PURPOSE: To assess the use of functional magnetic resonance imaging (MRI), including diffusion-weighted MRI (DWI) and magnetization transfer MRI (MTI) in evaluating male infertility. MATERIALS AND METHODS: Sixteen men with testicular spermatogenesis hypofunction confirmed by percutaneous testis biopsy and 31 volunteers (control group B, age range: 20-40 years) with normal semen analysis including younger (By, n = 15, age range: 20-30 years) and older (Bo, n = 16, age range: 31-40 years) men underwent pelvic 3T MRI, including DWI and MTI...
April 13, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28391789/microstructural-mr-imaging-techniques-in%C3%A2-multiple-sclerosis
#6
REVIEW
Massimo Filippi, Paolo Preziosa, Maria A Rocca
Due to its sensitivity in the detection of focal white matter (WM) lesions, MR imaging has become a paraclinical tool central to diagnosing multiple sclerosis (MS) and monitoring its evolution. Despite this, the correlation between patients' clinical status and conventional MR imaging measures is weak to moderate. Quantitative MR imaging-based techniques, such as magnetization transfer and diffusion tensor imaging, have a higher specificity toward the heterogeneous pathologic substrates of MS than MR imaging...
May 2017: Neuroimaging Clinics of North America
https://www.readbyqxmd.com/read/28390098/noninvasive-characterization-of-pancreatic-tumor-mouse-models-using-magnetic-resonance-imaging
#7
Navid Farr, Yak-Nam Wang, Samantha D'Andrea, Kayla M Gravelle, Joo Ha Hwang, Donghoon Lee
The preclinical models of pancreatic adenocarcinoma provide an alternative means for determining the mechanisms of malignancy and possibilities for treatments, thus representing a resource of immense potential for cancer treatment in medicine. To evaluate different tumor models, quantifiable magnetic resonance imaging (MRI) techniques can play a significant role in identifying valuable in vivo biomarkers of tumor characteristics. We characterized three models of pancreatic cancer with multiparametric MRI techniques...
April 7, 2017: Cancer Medicine
https://www.readbyqxmd.com/read/28382436/environmental-enrichment-reduces-brain-damage-in-hydrocephalic-immature-rats
#8
Carlos Henrique Rocha Catalão, Glaucia Yuri Shimizu, Jacqueline Atsuko Tida, Camila Araújo Bernardino Garcia, Antonio Carlos Dos Santos, Carlos Ernesto Garrido Salmon, Maria José Alves Rocha, Luiza da Silva Lopes
PURPOSE: We investigate the effects of environmental enrichment (EE) on morphological alterations in different brain structures of pup rats submitted to hydrocephalus condition. METHODS: Hydrocephalus was induced in 7-day-old pup rats by injection of 20% kaolin into the cisterna magna. Ventricular dilatation and magnetization transfer to analyze myelin were assessed by magnetic resonance. Hydrocephalic and control rats exposed to EE (n = 10 per group) were housed in cages with a tunnel, ramp, and colored plastic balls that would emit sound when touched...
April 5, 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/28349596/b1-sensitivity-analysis-of-quantitative-magnetization-transfer-imaging
#9
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/28321915/acceleration-of-asl-based-time-resolved-mr-angiography-by-acquisition-of-control-and-labeled-images-in-the-same-shot-actress
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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