keyword
MENU ▼
Read by QxMD icon Read
search

Low field MRI

keyword
https://www.readbyqxmd.com/read/29771534/nitroxyl-modified-tobacco-mosaic-virus-as-a-metal-free-high-relaxivity-mri-and-epr-active-superoxide-sensor
#1
Madushani Dharmarwardana, Andre F Martins, Zhuo Chen, Philip Palacios, Chance M Nowak, Raymond P Welch, Shaobo Li, Michael Andrew Luzuriaga, Leonidas Bleris, Brad S Pierce, A Dean Sherry, Jeremiah J Gassensmith
Superoxide overproduction is known to occur in multiple disease states requiring critical care yet non-invasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by "click conjugating" paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced in vivo to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species-in particular superoxide-and are largely unaffected by peroxides and molecular oxygen...
May 17, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29763453/anisotropic-conductivity-tensor-imaging-for-transcranial-direct-current-stimulation-tdcs-using-magnetic-resonance-diffusion-tensor-imaging-mr-dti
#2
Mun Bae Lee, Hyung Joong Kim, Eung Je Woo, Oh In Kwon
Transcranial direct current stimulation (tDCS) is a widely used non-invasive brain stimulation technique by applying low-frequency weak direct current via electrodes attached on the head. The tDCS using a fixed current between 1 and 2 mA has relied on computational modelings to achieve optimal stimulation effects. Recently, by measuring the tDCS current induced magnetic field using an MRI scanner, the internal current pathway has been successfully recovered. However, up to now, there is no technique to visualize electrical properties including the electrical anisotropic conductivity, effective extracellular ion-concentration, and electric field using only the tDCS current in-vivo...
2018: PloS One
https://www.readbyqxmd.com/read/29755312/integrated-fmri-preprocessing-framework-using-extended-kalman-filter-for-estimation-of-slice-wise-motion
#3
Basile Pinsard, Arnaud Boutin, Julien Doyon, Habib Benali
Functional MRI acquisition is sensitive to subjects' motion that cannot be fully constrained. Therefore, signal corrections have to be applied a posteriori in order to mitigate the complex interactions between changing tissue localization and magnetic fields, gradients and readouts. To circumvent current preprocessing strategies limitations, we developed an integrated method that correct motion and spatial low-frequency intensity fluctuations at the level of each slice in order to better fit the acquisition processes...
2018: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29753549/respiratory-motion-resolved-self-gated-4d-mri-using-rotating-cartesian-k-space-rock-initial-clinical-experience-on-an-mri-guided-radiotherapy-system
#4
Fei Han, Ziwu Zhou, Dongsu Du, Yu Gao, Shams Rashid, Minsong Cao, Narek Shaverdian, John V Hegde, Michael Steinberg, Percy Lee, Ann Raldow, Daniel A Low, Ke Sheng, Yingli Yang, Peng Hu
PURPOSE: To optimize and evaluate the respiratory motion-resolved, self-gated 4D-MRI using Rotating Cartesian K-space (ROCK-4D-MRI) method in a 0.35 T MRI-guided radiotherapy (MRgRT) system. METHODS AND MATERIALS: The study included seven patients with abdominal tumors treated on the MRgRT system. ROCK-4D-MRI and 2D-CINE, was performed immediately after one of the treatment fractions. Motion quantification based on 4D-MRI was compared with those based on 2D-CINE...
May 9, 2018: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29749974/design-of-sparse-halbach-magnet-arrays-for-portable-mri-using-a-genetic-algorithm
#5
Clarissa Zimmerman Cooley, Melissa W Haskell, Stephen F Cauley, Charlotte Sappo, Cristen D Lapierre, Christopher G Ha, Jason P Stockmann, Lawrence L Wald
Permanent magnet arrays offer several attributes attractive for the development of a low-cost portable MRI scanner for brain imaging. They offer the potential for a relatively lightweight, low to mid-field system with no cryogenics, a small fringe field, and no electrical power requirements or heat dissipation needs. The cylindrical Halbach array, however, requires external shimming or mechanical adjustments to produce B0 fields with standard MRI homogeneity levels (e.g., 0.1 ppm over FOV), particularly when constrained or truncated geometries are needed, such as a head-only magnet where the magnet length is constrained by the shoulders...
January 2018: IEEE Transactions on Magnetics
https://www.readbyqxmd.com/read/29727910/diagnostic-accuracy-of-mri-for-tumor-staging-of-bladder-cancer-systematic-review-and-meta-analysis
#6
Niket Gandhi, Satheesh Krishna, Christopher M Booth, Rodney H Breau, Trevor A Flood, Scott C Morgan, Nicola Schieda, Jean-Paul Salameh, Trevor Adam McGrath, Matthew McInnes
OBJECTIVES: To evaluate accuracy of MRI for local staging of bladder cancer for four clinical scenarios (T-stage thresholds) considered against current standards for clinical staging. Secondary objective is to identify sources for variability in accuracy. METHODS: Systematic review of patients with bladder cancer undergoing T-staging MRI to evaluate the diagnostic accuracy using bivariate random effects meta-analysis. Sub-group analysis was done to explore variability; risk of bias assessed using QUADAS-2...
May 4, 2018: BJU International
https://www.readbyqxmd.com/read/29726404/feasibility-study-of-fe-sub-3-sub-o-sub-4-sub-tao-sub-x-sub-nanoparticles-as-a-radiosensitizer-for-proton-therapy
#7
Sang Hee Ahn, Nohyun Lee, Changhoon Choi, Sung Won Shin, Youngyih Han, Hee Chul Park
We investigated the feasibility of using multifunctional Fe3O4/TaOx (core/shell) nanoparticles, developed for use in contrast agents for computed tomography (CT) and magnetic resonance imaging (MRI), as dose-enhancing radiosensitizers. First, to verify the detectability of Fe3O4/TaOx nanoparticles in imaging, in vivo tests were conducted. Approximately 600 mg/kg of 19-nm-diameter Fe3O4/TaOx nanoparticles dispersed in phosphate-buffered saline was injected into the tail vein of six Balb/c mice used as tumour (4T1 mammary carcinoma cell) models...
May 4, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29707813/microstructural-correlates-of-3d-steady-state-inhomogeneous-magnetization-transfer-ihmt-in-the-human-brain-white-matter-assessed-by-myelin-water-imaging-and-diffusion-tensor-imaging
#8
Ece Ercan, Gopal Varma, Burkhard Mädler, Ivan E Dimitrov, Marco C Pinho, Yin Xi, Benjamin C Wagner, Elizabeth M Davenport, Joseph A Maldjian, David C Alsop, Robert E Lenkinski, Elena Vinogradov
PURPOSE: To compare the recently introduced inhomogeneous magnetization transfer (ihMT) technique with more established MRI techniques including myelin water imaging (MWI) and diffusion tensor imaging (DTI), and to evaluate the microstructural attributes correlating with this new contrast method in the human brain white matter. METHODS: Eight adult healthy volunteers underwent T1 -weighted, ihMT, MWI, and DTI imaging on a 3T human scanner. The ihMT ratio (ihMTR), myelin water fraction (MWF), fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD), and mean diffusivity (MD) values were calculated from different white matter tracts...
April 29, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29676860/diagnostic-performance-of-diffusion-weighted-imaging-for-differentiating-benign-and-malignant-gallbladder-lesions-a-systematic-review-and-meta-analysis
#9
Myung-Won You, Seong Jong Yun
BACKGROUND: Although diffusion-weighted imaging (DWI) has been characterized as an alternative imaging modality for gallbladder (GB) lesions, it has not been routinely used in clinical practice because of relatively low signal-to-noise ratio. PURPOSE: To assess the sensitivity and specificity of the diagnostic performance of DWI for differentiating benign and malignant GB lesions. STUDY TYPE: Meta-analysis. POPULATION: Patients with GB lesions...
April 20, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29675474/brain-tumor-characterization-using-multibiometric-evaluation-of-mri
#10
Faris Durmo, Jimmy Lätt, Anna Rydelius, Silke Engelholm, Sara Kinhult, Krister Askaner, Elisabet Englund, Johan Bengzon, Markus Nilsson, Isabella M Björkman-Burtscher, Thomas Chenevert, Linda Knutsson, Pia C Sundgren
The aim was to evaluate volume, diffusion, and perfusion metrics for better presurgical differentiation between high-grade gliomas (HGG), low-grade gliomas (LGG), and metastases (MET). For this retrospective study, 43 patients with histologically verified intracranial HGG (n = 18), LGG (n = 10), and MET (n = 15) were chosen. Preoperative magnetic resonance data included pre- and post-gadolinium contrast-enhanced T1-weighted fluid-attenuated inversion recover, cerebral blood flow (CBF), cerebral blood volume (CBV), fractional anisotropy, and apparent diffusion coefficient maps used for quantification of magnetic resonance biometrics by manual delineation of regions of interest...
March 2018: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/29673893/a-new-discrete-dipole-kernel-for-quantitative-susceptibility-mapping
#11
Carlos Milovic, Julio Acosta-Cabronero, José Miguel Pinto, Hendrik Mattern, Marcelo Andia, Sergio Uribe, Cristian Tejos
PURPOSE: Most approaches for quantitative susceptibility mapping (QSM) are based on a forward model approximation that employs a continuous Fourier transform operator to solve a differential equation system. Such formulation, however, is prone to high-frequency aliasing. The aim of this study was to reduce such errors using an alternative dipole kernel formulation based on the discrete Fourier transform and discrete operators. METHODS: The impact of such an approach on forward model calculation and susceptibility inversion was evaluated in contrast to the continuous formulation both with synthetic phantoms and in vivo MRI data...
April 16, 2018: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29672976/dual-frequency-irradiation-cest-mri-of-endogenous-bulk-mobile-proteins
#12
Steffen Goerke, Johannes Breitling, Moritz Zaiss, Johannes Windschuh, Patrick Kunz, Patrick Schuenke, Daniel Paech, Dario L Longo, Karel D Klika, Mark E Ladd, Peter Bachert
A novel MRI contrast is proposed which enables the selective detection of endogenous bulk mobile proteins in vivo. Such a non-invasive imaging technique may be of particular interest for many diseases associated with pathological alterations of protein expression, such as cancer and neurodegenerative disorders. Specificity to mobile proteins was achieved by the selective measurement of intramolecular spin diffusion and the removal of semi-solid macromolecular signal components by a correction procedure. For this purpose, the approach of chemical exchange saturation transfer (CEST) was extended to a radiofrequency (RF) irradiation scheme at two different frequency offsets (dualCEST)...
April 19, 2018: NMR in Biomedicine
https://www.readbyqxmd.com/read/29657337/pressure-anisotropy-induced-nonlinearities-in-the-kinetic-magnetorotational-instability
#13
J Squire, E Quataert, M W Kunz
In collisionless and weakly collisional plasmas, such as hot accretion flows onto compact objects, the magnetorotational instability (MRI) can differ significantly from the standard (collisional) MRI. In particular, pressure anisotropy with respect to the local magnetic-field direction can both change the linear MRI dispersion relation and cause nonlinear modifications to the mode structure and growth rate, even when the field and flow perturbations are very small. This work studies these pressure-anisotropy-induced nonlinearities in the weakly nonlinear, high-ion-beta regime, before the MRI saturates into strong turbulence...
December 2017: Journal of Plasma Physics
https://www.readbyqxmd.com/read/29656440/in-plane-superresolution-mri-with-phaseless-sub-pixel-encoding
#14
Franciszek Hennel, Rui Tian, Maria Engel, Klaas P Pruessmann
PURPOSE: Acquisition of high-resolution imaging data using multiple excitations without the sensitivity to fluctuations of the transverse magnetization phase, which is a major problem of multi-shot MRI. THEORY AND METHODS: The concept of superresolution MRI based on microscopic tagging is analyzed using an analogy with the optical method of structured illumination. Sinusoidal tagging is shown to provide subpixel resolution by mixing of neighboring spatial frequency (k-space) bands...
April 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29648581/multiple-sclerosis-lesions-affect-intrinsic-functional-connectivity-of-the-spinal-cord
#15
Benjamin N Conrad, Robert L Barry, Baxter P Rogers, Satoshi Maki, Arabinda Mishra, Saakshi Thukral, Subramaniam Sriram, Aashim Bhatia, Siddharama Pawate, John C Gore, Seth A Smith
Patients with multiple sclerosis present with focal lesions throughout the spinal cord. There is a clinical need for non-invasive measurements of spinal cord activity and functional organization in multiple sclerosis, given the cord's critical role in the disease. Recent reports of spontaneous blood oxygenation level-dependent fluctuations in the spinal cord using functional MRI suggest that, like the brain, cord activity at rest is organized into distinct, synchronized functional networks among grey matter regions, likely related to motor and sensory systems...
April 10, 2018: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/29644479/design-of-a-sustainable-prepolarizing-magnetic-resonance-imaging-system-for-infant-hydrocephalus
#16
Johnes Obungoloch, Joshua R Harper, Steven Consevage, Igor M Savukov, Thomas Neuberger, Srinivas Tadigadapa, Steven J Schiff
OBJECTIVES: The need for affordable and appropriate medical technologies for developing countries continues to rise as challenges such as inadequate energy supply, limited technical expertise, and poor infrastructure persist. Low-field magnetic resonance imaging (LF MRI) is a technology that can be tailored to meet specific imaging needs within such countries. Its low power requirements and the possibility of operating in minimally shielded or unshielded environments make it especially attractive...
April 11, 2018: Magma
https://www.readbyqxmd.com/read/29619931/approaches-to-radiotherapy-in-metastatic-spinal-cord-compression
#17
Morten Hiul Suppl
Metastatic spinal cord compression is caused by the progression of metastatic lesions within the vicinity of the spinal cord. The consequences are very severe with loss of neurological function and severe pain. The standard treatment is surgical intervention followed by radiotherapy or radiotherapy alone. However, the majority of patients are treated with radiotherapy only due to contraindications to surgery and technical inoperability. Stereotactic body radiotherapy is a technology to deliver higher radiation dose to the radiotherapy target with the use of spatial coordinates...
April 2018: Danish Medical Journal
https://www.readbyqxmd.com/read/29606664/rheumatoid-arthritis-magnetic-resonance-imaging-score-predicts-therapy-response-results-of-the-german-arthromark-cohort
#18
Philipp Sewerin, Lien Le, Stefan Vordenbäumen, Christoph Schleich, Ruben Sengewein, Ralph Brinks, Georg Pongratz, Ellen Bleck, Juliane Lesch, Ulrich Mansmann, Matthias Schneider, Benedikt Ostendorf
OBJECTIVE: Markers for treatment response in rheumatoid arthritis (RA) are lacking. The aim of the study was to assess the performance of the RA magnetic resonance imaging (MRI) scoring system (RAMRIS) in combination with serum biomarkers to predict response to methotrexate (MTX) treatment in therapy-naive patients with early RA by using high-field MRI. METHODS: Twenty-eight patients with RA were prospectively assessed with baseline 3-T MRI of the clinical dominant hand, 3 and 6 months after MTX...
April 1, 2018: Journal of Rheumatology
https://www.readbyqxmd.com/read/29603047/a-novel-mr-compatible-sensor-to-assess-active-medical-device-safety-stimulation-monitoring-rectified-radio-frequency-pulses-and-gradient-induced-voltage-measurements
#19
Thérèse Barbier, Sarra Aissani, Nicolas Weber, Cédric Pasquier, Jacques Felblinger
PURPOSE: To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations. MATERIALS AND METHODS: An MRI-compatible voltage probe with a bandwidth of 0-40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1...
March 30, 2018: Magma
https://www.readbyqxmd.com/read/29598947/locoregional-extension-and-patterns-of-failure-for-nasopharyngeal-carcinoma-with-intracranial-extension
#20
Caineng Cao, Feng Jiang, Qifeng Jin, Ting Jin, Shuang Huang, Qiaoying Hu, Yuanyuan Chen, Yongfeng Piao, Yonghong Hua, Xinglai Feng, Xiaozhong Chen
OBJECTIVE: To evaluate the locoregional extension and patterns of failure for nasopharyngeal carcinoma (NPC) with intracranial extension to improve clinical target volume (CTV) delineation. PATIENTS AND METHODS: A total of 205 NPC patients with intracranial extension by magnetic resonance imaging (MRI) were retrospectively reviewed. RESULTS: According to the cumulative incidence rates of tumor invasion, we initially classified anatomic sites surrounding the nasopharynx into three risk grades: high risk (≥35%), medium risk (≥10-35%), and low risk (<10%)...
April 2018: Oral Oncology
keyword
keyword
113472
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"