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Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine

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https://www.readbyqxmd.com/read/28097749/positive-contrast-from-cells-labeled-with-iron-oxide-nanoparticles-quantitation-of-imaging-data
#1
Sergey Magnitsky, Jinjin Zhang, Djaudat Idiyatullin, Geetha Mohan, Michael Garwood, Nancy E Lane, Sharmila Majumdar
PURPOSE: Conventional T2 -weighted MRI produces a hypointense signal from iron-labeled cells, which renders quantification unfeasible. We tested a SWeep Imaging with Fourier Transformation (SWIFT) MRI pulse sequence to generate a quantifiable hyperintense signal from iron-labeled cells. METHODS: Mesenchymal stem cells (MSCs) were labeled with different concentrations of iron oxide particles and examined for cell viability, proliferation, and differentiation. The SWIFT sequence was optimized to detect and quantify the amount of iron in the muscle tissue after injection of iron oxide solution and iron-labeled MSCs...
January 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28097733/optimized-amplitude-modulated-multiband-rf-pulse-design
#2
Samy Abo Seada, Anthony N Price, Joseph V Hajnal, Shaihan J Malik
PURPOSE: Multiband pulses are characterized by highly temporally modulated waveforms. Rapid phase or frequency modulation can be extremely demanding on the performance of radiofrequency (RF) pulse generation, which can lead to errors that can be avoided if pulses are restricted to amplitude modulation (AM) only. In this work, three existing multiband pulse design techniques are modified to produce AM waveforms. THEORY AND METHODS: Multiband refocusing pulses were designed using phase optimization, time shifting, and root flipping...
January 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28097689/investigating-magnetic-susceptibility-of-human-knee-joint-at-7-tesla
#3
Hongjiang Wei, Russell Dibb, Kyle Decker, Nian Wang, Yuyao Zhang, Xiaopeng Zong, Weili Lin, Daniel B Nissman, Chunlei Liu
PURPOSE: To evaluate the magnetic susceptibility properties of different anatomical structures within the knee joint using quantitative susceptibility mapping (QSM). METHODS: A collagen tissue model was simulated and ex vivo animal cartilage experiments were conducted at 9.4 Tesla (T) to evaluate the B0 orientation-dependent magnetic susceptibility contrast observed in cartilage. Furthermore, nine volunteers (six healthy subjects without knee pain history and three patients with known knee injury, between 29 and 58 years old) were scanned using gradient-echo acquisitions on a high-field 7T MR scanner...
January 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28097687/requirements-for-accurate-estimation-of-anisotropic-material-parameters-by-magnetic-resonance-elastography-a-computational-study
#4
D J Tweten, R J Okamoto, P V Bayly
PURPOSE: To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). THEORY AND METHODS: Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1...
January 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090666/quantitative-ultrashort-echo-time-imaging-for-assessment-of-massive-iron-overload-at-1-5-and-3-tesla
#5
Axel J Krafft, Ralf B Loeffler, Ruitian Song, Aaryani Tipirneni-Sajja, M Beth McCarville, Matthew D Robson, Jane S Hankins, Claudia M Hillenbrand
PURPOSE: Hepatic iron content (HIC) quantification via transverse relaxation rate (R2*)-MRI using multi-gradient echo (mGRE) imaging is compromised toward high HIC or at higher fields due to the rapid signal decay. Our study aims at presenting an optimized 2D ultrashort echo time (UTE) sequence for R2* quantification to overcome these limitations. METHODS: Two-dimensional UTE imaging was realized via half-pulse excitation and radial center-out sampling. The sequence includes chemically selective saturation pulses to reduce streaking artifacts from subcutaneous fat, and spatial saturation (sSAT) bands to suppress out-of-slice signals...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090665/can-patel-s-%C3%AF-accurately-estimate-directionality-of-connections-in-brain-networks-from-fmri
#6
Yunzhi Wang, Olivier David, Xiaoping Hu, Gopikrishna Deshpande
PURPOSE: Investigating directional interactions between brain regions plays a critical role in fully understanding brain function. Consequently, multiple methods have been developed for noninvasively inferring directional connectivity in human brain networks using functional MRI (fMRI). Recent simulations by Smith et al showed that Patel's τ, a method based on higher-order statistics, was the best approach for inferring directional interactions from fMRI. Because simulations make restrictive assumptions about reality, we set out to verify this finding using experimental fMRI data obtained from a three-region network in a rat model with electrophysiological validation...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090658/analysis-of-the-effects-of-noise-dwi-sampling-and-value-of-assumed-parameters-in-diffusion-mri-models
#7
Elizabeth B Hutchinson, Alexandru V Avram, M Okan Irfanoglu, C Guan Koay, Alan S Barnett, Michal E Komlosh, Evren Özarslan, Susan C Schwerin, Sharon L Juliano, Carlo Pierpaoli
PURPOSE: This study was a systematic evaluation across different and prominent diffusion MRI models to better understand the ways in which scalar metrics are influenced by experimental factors, including experimental design (diffusion-weighted imaging [DWI] sampling) and noise. METHODS: Four diffusion MRI models-diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), mean apparent propagator MRI (MAP-MRI), and neurite orientation dispersion and density imaging (NODDI)-were evaluated by comparing maps and histogram values of the scalar metrics generated using DWI datasets obtained in fixed mouse brain with different noise levels and DWI sampling complexity...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090656/real-time-monitoring-of-tissue-displacement-and-temperature-changes-during-mr-guided-high-intensity-focused-ultrasound
#8
Pierre Bour, Fabrice Marquet, Valéry Ozenne, Solenn Toupin, Erik Dumont, Jean-François Aubry, Matthieu Lepetit-Coiffe, Bruno Quesson
PURPOSE: The therapy endpoint most commonly used in MR-guided high intensity focused ultrasound is the thermal dose. Although namely correlated with nonviable tissue, it does not account for changes in mechanical properties of tissue during ablation. This study presents a new acquisition sequence for multislice, subsecond and simultaneous imaging of tissue temperature and displacement during ablation. METHODS: A single-shot echo planar imaging sequence was implemented using a pair of motion-encoding gradients, with alternated polarities...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28090655/30-second-bound-and-pore-water-concentration-mapping-of-cortical-bone-using-2d-ute-with-optimized-half-pulses
#9
Mary Kate Manhard, Kevin D Harkins, Daniel F Gochberg, Jeffry S Nyman, Mark D Does
PURPOSE: MRI of cortical bone has the potential to offer new information about fracture risk. Current methods are typically performed with 3D acquisitions, which suffer from long scan times and are generally limited to extremities. This work proposes using 2D UTE with half pulses for quantitatively mapping bound and pore water in cortical bone. METHODS: Half-pulse 2D UTE methods were implemented on a 3T Philips Achieva scanner using an optimized slice-select gradient waveform, with preparation pulses to selectively image bound or pore water...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28078795/a-continuous-infusion-dynamic-mri-model-at-3-0-tesla-for-the-serial-quantitative-evaluation-of-microvascular-proliferation-in-an-animal-model-of-glioblastoma-multiforme
#10
Hunter R Underhill
PURPOSE: To develop a continuous-infusion dynamic MRI technique to characterize tumor-associated microvascular proliferation (MVP) in a rat brain model of glioblastoma multiforme. METHODS: The proposed model assumes effects due to tumor-associated MVP (eg, vascular permeability, K(trans) ; intravascular plasma fraction, vp ) cannot be individually separated and solves for a single parameter (k(vasc) ) that quantifies the T1 -weighted contrast enhancement from dynamic images acquired during continuous contrast agent (CA) infusion...
January 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074609/rapid-chemical-shift-encoding-with-single-acquisition-single-slab-3d-grase
#11
Hahnsung Kim, Dong-Hyun Kim, Chul-Ho Sohn, Jaeseok Park
PURPOSE: To investigate the feasibility of chemical shift encoded, single-slab 3D GRASE for rapid fat-water separation within a single acquisition. METHODS: The proposed method incorporates signal-to-noise-ratio-optimal chemical shift encoding into single-slab 3D GRASE with variable flip angles. Chemical shift induced phase information was encoded in succession to different positions in k-space by inserting phase encoding blips between adjacent lobes of the oscillating readout gradients...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074541/comparison-of-respiratory-motion-suppression-techniques-for-4d-flow-mri
#12
Petter Dyverfeldt, Tino Ebbers
PURPOSE: The purpose of this work was to assess the impact of respiratory motion and to compare methods for suppression of respiratory motion artifacts in 4D Flow MRI. METHODS: A numerical 3D aorta phantom was designed based on an aorta velocity field obtained by computational fluid mechanics. Motion-distorted 4D Flow MRI measurements were simulated and several different motion-suppression techniques were evaluated: Gating with fixed acceptance window size, gating with different window sizes in inner and outer k-space, and k-space reordering...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074530/slice-profile-and-b1-corrections-in-2d-magnetic-resonance-fingerprinting
#13
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/28074498/imaging-and-t2-relaxometry-of-short-t2-connective-tissues-in-the-knee-using-ultrashort-echo-time-double-echo-steady-state-utedess
#14
Akshay S Chaudhari, Bragi Sveinsson, Catherine J Moran, Emily J McWalter, Ethan M Johnson, Tao Zhang, Garry E Gold, Brian A Hargreaves
PURPOSE: To develop a radial, double-echo steady-state (DESS) sequence with ultra-short echo-time (UTE) capabilities for T2 measurement of short-T2 tissues along with simultaneous rapid, signal-to-noise ratio (SNR)-efficient, and high-isotropic-resolution morphological knee imaging. METHODS: THe 3D radial UTE readouts were incorporated into DESS, termed UTEDESS. Multiple-echo-time UTEDESS was used for performing T2 relaxometry for short-T2 tendons, ligaments, and menisci; and for Dixon water-fat imaging...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074497/in-vivo-imaging-of-the-progression-of-acute-lung-injury-using-hyperpolarized-1-13-c-pyruvate
#15
Mehrdad Pourfathi, Yi Xin, Stephen J Kadlecek, Maurizio F Cereda, Harrilla Profka, Hooman Hamedani, Sarmad M Siddiqui, Kai Ruppert, Nicholas A Drachman, Jennia N Rajaei, Rahim R Rizi
PURPOSE: To investigate pulmonary metabolic alterations during progression of acute lung injury. METHODS: Using hyperpolarized [1-(13) C] pyruvate imaging, we measured pulmonary lactate and pyruvate in 15 ventilated rats 1, 2, and 4 h after initiation of mechanical ventilation. Lung compliance was used as a marker for injury progression. 5 untreated rats were used as controls; 5 rats (injured-1) received 1 ml/kg and another 5 rats (injured-2) received 2 ml/kg hydrochloric acid (pH 1...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074492/confirmation-of-resting-state-bold-fluctuations-in-the-human-brainstem-and-spinal-cord-after-identification-and-removal-of-physiological-noise
#16
Shreyas Harita, Patrick W Stroman
PURPOSE: Resting-state functional MRI (rs-fMRI) has been used to investigate networks within the cortex, but its use in the brainstem (BS) and spinal cord (SC) has been limited. This region presents challenges for fMRI, partly because of sources of physiological noise. This study aims to quantify noise contributions to rs-fMRI, and to obtain evidence of resting-state blood oxygenation level-dependent (BOLD) fluctuations. METHODS: Resting-state-fMRI data were obtained from the BS/SC in 16 participants, at 3 Tesla, with T2 -weighted single-shot fast spin-echo imaging...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28070897/stable-spline-deconvolution-for-dynamic-susceptibility-contrast-mri
#17
Denis Peruzzo, Marco Castellaro, Gianluigi Pillonetto, Alessandra Bertoldo
PURPOSE: To present the stable spline (SS) deconvolution method for the quantification of the cerebral blood flow (CBF) from dynamic susceptibility contrast MRI. METHODS: The SS method was compared with both the block-circulant singular value decomposition (oSVD) and nonlinear stochastic regularization (NSR) methods. oSVD is one of the most popular deconvolution methods in dynamic susceptibility contrast MRI (DSC-MRI). NSR is an alternative approach that we proposed previously...
January 9, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28054416/anomalous-diffusion-in-cerebral-glioma-assessed-using-a-fractional-motion-model
#18
Boyan Xu, Lu Su, Zhenxiong Wang, Yang Fan, Gaolang Gong, Wenzhen Zhu, Peiyi Gao, Jia-Hong Gao
PURPOSE: To demonstrate the capability of the fractional motion (FM) model for describing anomalous diffusion in cerebral gliomas and to assess the potential feasibility of FM for grading these tumors. METHODS: Diffusion MRI images were acquired from brain tumor patients using a special Stejskal-Tanner diffusion sequence with variable diffusion gradient amplitudes and separation times. Patients with histopathologically confirmed gliomas, including astrocytic and oligoastrocytic tumors, were selected...
January 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28039883/a-regularized-model-based-approach-to-phase-based-conductivity-mapping-using-mri
#19
Kathleen M Ropella, Douglas C Noll
PURPOSE: To develop a novel regularized, model-based approach to phase-based conductivity mapping that uses structural information to improve the accuracy of conductivity maps. THEORY AND METHODS: The inverse of the three-dimensional Laplacian operator is used to model the relationship between measured phase maps and the object conductivity in a penalized weighted least-squares optimization problem. Spatial masks based on structural information are incorporated into the problem to preserve data near boundaries...
December 30, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28026061/detection-of-smoke-induced-pulmonary-lesions-by-hyperpolarized-129-xe-diffusion-kurtosis-imaging-in-rat-models
#20
Weiwei Ruan, Jianping Zhong, Yu Guan, Yi Xia, Xiuchao Zhao, Yeqing Han, Xianping Sun, Shiyuan Liu, Chaohui Ye, Xin Zhou
PURPOSE: To demonstrate that hyperpolarized (HP) xenon diffusion kurtosis imaging (DKI) is able to detect smoke-induced pulmonary lesions in rat models. METHODS: Multi-b DKI with hyperpolarized xenon was used for the first time in five smoke-exposed rats and five healthy rats. Additionally, DKI with b values of up to 80 s/cm(2) were used in two healthy rats to probe the critical b value (a limit beyond which the DKI cannot describe the non-Gaussian diffusion). RESULTS: The mean apparent diffusion coefficient (Dapp ) and diffusion kurtosis (Kapp ) extracted by the DKI model revealed significant changes in the smoke-exposed rats compared with those in the control group (P = 0...
December 27, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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