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Artículos de revistas sobre el tema "Applied Physics, Magnetic Resonance Imaging, Magnetic Particle Imaging"

Autor: Grafiati

Publicado: 11 de marzo de 2023

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1

Herrmann, Anne, Arthur Taylor, Patricia Murray, Harish Poptani y Violaine Sée. "Magnetic Resonance Imaging for Characterization of a Chick Embryo Model of Cancer Cell Metastases". Molecular Imaging 17 (1 de enero de 2018): 153601211880958. http://dx.doi.org/10.1177/1536012118809585.

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Metastasis is the most common cause of death for patients with cancer. To fully understand the steps involved in metastatic dissemination, in vivo models are required, of which murine ones are the most common. Therefore, preclinical imaging methods such as magnetic resonance imaging (MRI) have mainly been developed for small mammals and their potential to monitor cancer growth and metastasis in nonmammalian models is not fully harnessed. We have here used MRI to measure primary neuroblastoma tumor size and metastasis in a chick embryo model. We compared its sensitivity and accuracy to end-point fluorescence detection upon dissection. Human neuroblastoma cells labeled with green fluorescent protein (GFP) and micron-sized iron particles were implanted on the extraembryonic chorioallantoic membrane of the chick at E7. T2 RARE, T2-weighted fast low angle shot (FLASH) as well as time-of-flight MR angiography imaging were applied at E14. Micron-sized iron particle labeling of neuroblastoma cells allowed in ovo observation of the primary tumor and tumor volume measurement noninvasively. Moreover, T2 weighted and FLASH imaging permitted the detection of small metastatic deposits in the chick embryo, thereby reinforcing the potential of this convenient, 3R compliant, in vivo model for cancer research.

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2

Baki, Abdulkader, Amani Remmo, Norbert Löwa, Frank Wiekhorst y Regina Bleul. "Albumin-Coated Single-Core Iron Oxide Nanoparticles for Enhanced Molecular Magnetic Imaging (MRI/MPI)". International Journal of Molecular Sciences 22, n.º 12 (9 de junio de 2021): 6235. http://dx.doi.org/10.3390/ijms22126235.

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Colloidal stability of magnetic iron oxide nanoparticles (MNP) in physiological environments is crucial for their (bio)medical application. MNP are potential contrast agents for different imaging modalities such as magnetic resonance imaging (MRI) and magnetic particle imaging (MPI). Applied as a hybrid method (MRI/MPI), these are valuable tools for molecular imaging. Continuously synthesized and in-situ stabilized single-core MNP were further modified by albumin coating. Synthesizing and coating of MNP were carried out in aqueous media without using any organic solvent in a simple procedure. The additional steric stabilization with the biocompatible protein, namely bovine serum albumin (BSA), led to potential contrast agents suitable for multimodal (MRI/MPI) imaging. The colloidal stability of BSA-coated MNP was investigated in different sodium chloride concentrations (50 to 150 mM) in short- and long-term incubation (from two hours to one week) using physiochemical characterization techniques such as transmission electron microscopy (TEM) for core size and differential centrifugal sedimentation (DCS) for hydrodynamic size. Magnetic characterization such as magnetic particle spectroscopy (MPS) and nuclear magnetic resonance (NMR) measurements confirmed the successful surface modification as well as exceptional colloidal stability of the relatively large single-core MNP. For comparison, two commercially available MNP systems were investigated, MNP-clusters, the former liver contrast agent (Resovist), and single-core MNP (SHP-30) manufactured by thermal decomposition. The tailored core size, colloidal stability in a physiological environment, and magnetic performance of our MNP indicate their ability to be used as molecular magnetic contrast agents for MPI and MRI.

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3

Cenova, Iva, David Kauzlarić, Andreas Greiner y Jan G. Korvink. "Constrained simulations of flow in haemodynamic devices: towards a computational assistance of magnetic resonance imaging measurements". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, n.º 1945 (28 de junio de 2011): 2494–501. http://dx.doi.org/10.1098/rsta.2011.0028.

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Cardiovascular diseases, mostly related to atherosclerosis, are the major cause of death in industrial countries. It is observed that blood flow dynamics play an important role in the aetiology of atherosclerosis. Especially, the blood velocity distribution is an important indicator for predisposition regions. Today magnetic resonance imaging (MRI) delivers, in addition to the morphology of the cardiovascular system, blood flow patterns. However, the spatial resolution of the data is slightly less than 1 mm and owing to severe restrictions in magnetic field gradient switching frequencies and intensities, this limit will be very hard to overcome. In this paper, constrained fluid dynamics is applied within the smoothed particle hydrodynamics formalism to enhance the MRI flow data. On the one hand, constraints based on the known volumetric flow rate are applied. They prove the plausibility of the order of magnitude of the measurements. On the other hand, the higher resolution of the simulation allows one to determine in detail the flow field between the coarse data points and thus to improve their spatial resolution.

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4

TOUFIQ, ARBAB MOHAMMAD, FENGPING WANG, QURAT-UL-AIN JAVED, QUANSHUI LI y YAN LI. "PHOTOLUMINESCENCE SPECTRA AND MAGNETIC PROPERTIES OF HYDROTHERMALLY SYNTHESIZED MnO2 NANORODS". Modern Physics Letters B 27, n.º 29 (15 de noviembre de 2013): 1350211. http://dx.doi.org/10.1142/s0217984913502114.

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In this paper, single crystalline tetragonal MnO 2 nanorods have been synthesized by a simple hydrothermal method using MnSO 4⋅ H 2 O and Na 2 S 2 O 8 as precursors. The crystalline phase, morphology, particle sizes and component of the as-prepared nanomaterial were characterized by employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). The photoluminescence (PL) emission spectrum of MnO 2 nanorods at room temperature exhibited a strong ultraviolet (UV) emission band at 380 nm, a prominent blue emission peak at 453 nm as well as a weak defect related green emission at 553 nm. Magnetization (M) as a function of applied magnetic field (H) curve showed that MnO 2 nanowires exhibited a superparamagnetic behavior at room temperature which shows the promise of synthesized MnO 2 nanorods for applications in ferrofluids and the contrast agents for magnetic resonance imaging. The magnetization versus temperature curve of the as-obtained MnO 2 nanorods shows that the Néel transition temperature is 94 K.

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5

Ragam, Prashanth y Devidas Sahebraoji Nimaje. "Evaluation and prediction of blast-induced peak particle velocity using artificial neural network: A case study". Noise & Vibration Worldwide 49, n.º 3 (marzo de 2018): 111–19. http://dx.doi.org/10.1177/0957456518763161.

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Over the past few decades, inducing of ground vibrations from blasting may cause severe damage to surrounding structures, plants, and human beings in the mining industry. Therefore, it is essential to monitor and predict the ambiguous vibration levels and take measures to reduce their hazardous effect. In this study, to evaluate and predict the ambiguous ground vibrations, an application of artificial neural network technique was used. A three-layer, feed-forward back-propagation multilayer perception neural network having six input parameters, the distance from blast face, maximum charge per delay, spacing, burden, hole depth and a number of holes, and one output: peak particle velocity, was used and trained with the Levenberg–Marquardt algorithm using 25 experimental and blast event records from the iron ore mine A, India. To determine the efficiency and accuracy of the developed artificial neural network model, seven conventional predictor models proposed by the US Bureau of Mines, Ambraseys–Hendron, Langefors–Kihlstrom, general predictor, Ghosh–Daemen predictor, cardiac magnetic resonance imaging (CMRI) predictor, Bureau of Indian Standards, as well as multiple linear regression, were applied to establish a relation between peak particle velocity and its influencing parameters. The obtained results reveal that the proposed artificial neural network model can estimate ground vibrations more accurately as compared with the various conventional predictor models available. Coefficient of determination (R2) and root mean square error indices were obtained as 0.9971 and 0.08133 for artificial neural network model, respectively.

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6

Korsakova, Alina S., Dzmitry A. Kotsikau, Yulyan S. Haiduk y Vladimir V. Pankov. "Synthesis and Physicochemical Properties of MnxFe3–xO4 Solid Solutions". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 22, n.º 4 (1 de diciembre de 2020): 466–72. http://dx.doi.org/10.17308/kcmf.2020.22/3076.

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Ferrimagnetic nanoparticles are used in biotechnology (as drug carriers, biosensors, elements of diagnostic sets, contrast agents for magnetic resonance imaging), catalysis, electronics, and for the production of magnetic fluids and magnetorheological suspensions, etc. The use of magnetic nanoparticles requires enhanced magnetic characteristics, in particular, high saturation magnetisation.The aim of our study was to obtain single-phased magnetic nanoparticles of MnxFe3–xO4 solid solutions at room temperature. We also studied the dependence of the changes in their structure, morphology, and magnetic properties on the degree of substitution in order to determine the range of the compounds with the highest magnetisation value.A number of powders of Mn-substituted magnetite MnxFe3–xO4 (x = 0 – 1.8) were synthesized by means of co-precipitation from aqueous solutions of salts. The structural and micro-structural features and magnetic properties of the powders were studied using magnetic analysis, X-ray diffraction, transmission electron microscopy, and IR spectroscopy.The X-ray phase analysis and IR spectroscopy confirm the formation of single-phase compounds with cubic spinel structures. The maximum increase in saturation magnetization as compared to non-substituted magnetite was observed for Mn0.3Fe2.7O4 (Ms = 68 A·m2·kg–1 at 300 K and Ms = 85 A·m2·kg–1 at 5 K). This is associated with the changes in the cation distribution between the tetrahedral and octahedral cites.A method to control the magnetic properties of magnetite by the partial replacement of iron ions in the magnetite structure with manganese has been proposed in the paper. The study demonstrated that it is possible to change the magnetisation and coercivity of powders by changing the degree of substitution. The maximum magnetisation corresponds to the powder Mn0.3Fe2.7O4. The nanoparticles obtained by the proposed method have a comparatively high specific magnetisation and a uniform size distribution. Therefore the developed materials can be used for the production of magnetorheological fluidsand creation of magnetically controlled capsules for targeted drug delivery and disease diagnostics in biology and medicine (magnetic resonance imaging). References1. Gubin C. G., Koksharov Yu. A., Khomutov G. B.,Yurkov G. Yu. Magnetic nanoparticles: preparation,structure and properties. Russian Chemical Reviews2005;74(6): 539–574. Available at: https://www.elibrary.ru/item.asp?id=90858192. Skumr yev V. , Stoyanov S. , Zhang Y. ,Hadjipanayis G., Givord D., Nogués J. Beating thesuperparamagnetic limit with exchange bias. Nature.2003;423(6943): 850–853. DOI: https://doi.org/10.1038/nature016873. Joseph A., Mathew S. Ferrofluids: syntheticstrategies, stabilization, physicochemical features, characterization, and applications. ChemPlusChem.2014;79(10): 1382–1420. DOI: https://doi.org/10.1002/cplu.2014022024. Mathew D. S., Juang R.-S. An overview of thestructure and magnetism of spinel ferrite nanoparticlesand their synthesis in microemulsions. ChemicalEngineering Journal. 2007:129(1–3): 51–65. DOI:https://doi.org/10.1016/j.cej.2006.11.0015. Rewatkar K. G. Magnetic nanoparticles:synthesis and properties. Solid State Phenomena.2016:241: 177–201. DOI: https://doi.org/10.4028/www.scientific.net/ssp.241.1776. Tartaj P., Morales M. P., Veintemillas-VerdaguerS., Gonzalez-Carre´no T., Serna C. J. Thepreparation of magnetic nanoparticles for applicationsin biomedicine. Journal of Physics D: Applied Physics.2003: 36 (13): 182–197. DOI: : https://doi.org/10.1088/0022-3727/36/13/2027. West A. Khimiya tverdogo tela. Teoriya iprilozheniya [Solid State Chemistry and Its Applications].In 2 parts Part 1. Transl. from English. Moscow, Mir,1988 558 p.8. Spravochnik khimika: V 6 t. 2-e izd. Obshchiyesvedeniya. Stroyeniye veshchestva. Svoystva vazhneyshikhveshchestv. Laboratornaya tekhnika [Chemist’sHandbook: In 6 volumes, 2nd ed. General information.The structure of matter. Properties of the mostimportant substances. Laboratory equipment]. B. P.Nikolskiy (ed.) Moscow – Leningrad: GoskhimizdatPubl.; 1963. V. 1. 1071 p. (In Russ.)9. Zhuravlev G. I. Khimiya i tekhnologiya ferritov[Ferrite chemistry and technology]. Leningrad:Khimiya Publ.; 1970. p. 192. (In Russ.)10. Mason B. Mineralogical aspects of the systemFeO-Fe2O3-MnO-Mn2O3. Geologiska Föreningen iStockholm Förhandlingar. 1943;65(2): 97–180. DOI:https://doi.org/10.1080/1103589430944714211. Guillemet-Fritsch S., Navrotsky A., TailhadesPh., Coradin H., Wang M. Thermochemistry of ironmanganese oxide spinels. Journal of Solid StateChemistry. 2005;178(1):106–113. DOI: https://doi.org/10.1016/j.jssc.2004.10.03112. Ortega D. Structure and magnetism in magneticnanoparticles. In: Magnetic Nanoparticles: FromFabrication to Clinical Applications. Boca Raton: CRCPress; 2012. p. 3–72. DOI:https://doi.org/10.1201/b11760-313. Kodama T., Ookubo M., Miura S., Kitayama Y.Synthesis and characterization of ultrafine Mn(II)-bearing ferrite of type MnxFe3-xO4 by coprecipitation.Materials Research Bulletin... 1996:31(12): 1501–1512.DOI: https://doi.org/10.1016/s0025-5408(96)00146-814. Al-Rashdi K. S., Widatallah H., Al Ma’Mari F.,Cespedes O., Elzain M., Al-Rawas A., Gismelseed A.,Yousif A. Structural and mossbauer studies ofnanocrystalline Mn2+ doped Fe3O4 particles. HyperfineInteract. 2018:239(1): 1–11. DOI: https://doi.org/10.1007/s10751-017-1476-915. Modaresi N., Afzalzadeh R., Aslibeiki B.,Kameli P. Competition between the Impact of cationdistribution and crystallite size on properties ofMnxFe3–xO4 nanoparticles synthesized at roomtemperature. Ceramics International. 2017:43(17):15381–15391. DOI: https://doi.org/10.1016/j.ceramint.2017.08.079

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7

Paysen, Hendrik, Norbert Loewa, Karol Weber, Olaf Kosch, James Wells, Tobias Schaeffter y Frank Wiekhorst. "Imaging and quantification of magnetic nanoparticles: Comparison of magnetic resonance imaging and magnetic particle imaging". Journal of Magnetism and Magnetic Materials 475 (abril de 2019): 382–88. http://dx.doi.org/10.1016/j.jmmm.2018.10.082.

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8

Wegner, Franz, Kerstin Lüdtke-Buzug, Sjef Cremers, Thomas Friedrich, Malte M. Sieren, Julian Haegele, Martin A. Koch et al. "Bimodal Interventional Instrument Markers for Magnetic Particle Imaging and Magnetic Resonance Imaging—A Proof-of-Concept Study". Nanomaterials 12, n.º 10 (21 de mayo de 2022): 1758. http://dx.doi.org/10.3390/nano12101758.

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The purpose of this work was to develop instrument markers that are visible in both magnetic particle imaging (MPI) and magnetic resonance imaging (MRI). The instrument markers were based on two different magnetic nanoparticle types (synthesized in-house KLB and commercial Bayoxide E8706). Coatings containing one of both particle types were fabricated and measured with a magnetic particle spectrometer (MPS) to estimate their MPI performance. Coatings based on both particle types were then applied on a segment of a nonmetallic guidewire. Imaging experiments were conducted using a commercial, preclinical MPI scanner and a preclinical 1 tesla MRI system. MPI image reconstruction was performed based on system matrices measured with dried KLB and Bayoxide E8706 coatings. The bimodal markers were clearly visible in both methods. They caused circular signal voids in MRI and areas of high signal intensity in MPI. Both the signal voids as well as the areas of high signal intensity were larger than the real marker size. Images that were reconstructed with a Bayoxide E8706 system matrix did not show sufficient MPI signal. Instrument markers with bimodal visibility are essential for the perspective of monitoring cardiovascular interventions with MPI/MRI hybrid systems.

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9

Gladden, Lynn F. "Applications of Nuclear Magnetic Resonance Imaging in Particle Technology". Particle & Particle Systems Characterization 12, n.º 2 (abril de 1995): 59–67. http://dx.doi.org/10.1002/ppsc.19950120203.

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10

Kluth, Tobias. "Mathematical models for magnetic particle imaging". Inverse Problems 34, n.º 8 (12 de junio de 2018): 083001. http://dx.doi.org/10.1088/1361-6420/aac535.

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11

Epstein, Charles L. "Magnetic resonance imaging in inhomogeneous fields". Inverse Problems 20, n.º 3 (19 de marzo de 2004): 753–80. http://dx.doi.org/10.1088/0266-5611/20/3/007.

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12

Garcia, Nissa C., Dindi Yu, Li Yao y Shoujun Xu. "Optical atomic magnetometer at body temperature for magnetic particle imaging and nuclear magnetic resonance". Optics Letters 35, n.º 5 (24 de febrero de 2010): 661. http://dx.doi.org/10.1364/ol.35.000661.

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13

Taylor, Annette F. y Melanie M. Britton. "Magnetic resonance imaging of chemical waves in porous media". Chaos: An Interdisciplinary Journal of Nonlinear Science 16, n.º 3 (2006): 037103. http://dx.doi.org/10.1063/1.2228129.

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14

Dong, Guozhi, Michael Hintermüller y Kostas Papafitsoros. "Quantitative Magnetic Resonance Imaging: From Fingerprinting to Integrated Physics-Based Models". SIAM Journal on Imaging Sciences 12, n.º 2 (enero de 2019): 927–71. http://dx.doi.org/10.1137/18m1222211.

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15

Puiseux, Thomas, Anou Sewonu, Ramiro Moreno, Simon Mendez y Franck Nicoud. "Numerical simulation of time-resolved 3D phase-contrast magnetic resonance imaging". PLOS ONE 16, n.º 3 (26 de marzo de 2021): e0248816. http://dx.doi.org/10.1371/journal.pone.0248816.

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A numerical approach is presented to efficiently simulate time-resolved 3D phase-contrast Magnetic resonance Imaging (or 4D Flow MRI) acquisitions under realistic flow conditions. The Navier-Stokes and Bloch equations are simultaneously solved with an Eulerian-Lagrangian formalism. A semi-analytic solution for the Bloch equations as well as a periodic particle seeding strategy are developed to reduce the computational cost. The velocity reconstruction pipeline is first validated by considering a Poiseuille flow configuration. The 4D Flow MRI simulation procedure is then applied to the flow within an in vitro flow phantom typical of the cardiovascular system. The simulated MR velocity images compare favorably to both the flow computed by solving the Navier-Stokes equations and experimental 4D Flow MRI measurements. A practical application is finally presented in which the MRI simulation framework is used to identify the origins of the MRI measurement errors.

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16

Ivanov, V. A. "History and prospects of employing magnetic-resonance imaging". Journal of Optical Technology 67, n.º 4 (1 de abril de 2000): 399. http://dx.doi.org/10.1364/jot.67.000399.

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17

Meribout, Mahmoud y Mohit Kalra. "A portable system for two dimensional magnetic particle imaging". Measurement 152 (febrero de 2020): 107281. http://dx.doi.org/10.1016/j.measurement.2019.107281.

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18

Garrido, Leoncio y José Sampayo. "Proton Magnetic Resonance Imaging of Specimens in Simulated Microgravity". Microgravity Science and Technology 21, n.º 4 (27 de enero de 2009): 305–10. http://dx.doi.org/10.1007/s12217-009-9105-0.

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19

Cirilli, Manuela. "From particle physics: To medtech and biomedical research". Europhysics News 49, n.º 5-6 (septiembre de 2018): 35–38. http://dx.doi.org/10.1051/epn/2018507.

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Physics phenomena underpin many techniques and technologies that are used for both diagnosis and treatment of a variety of diseases. This is the case for radiotherapy, Magnetic Resonance Imaging (MRI), and Positron Emission Tomography (PET) that are based on our knowledge, respectively, of how particles interact with matter, of how atomic nuclei behave in oscillating magnetic fields, and of how positron decay.

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20

Hammernik, Kerstin, Thomas Kustner, Burhaneddin Yaman, Zhengnan Huang, Daniel Rueckert, Florian Knoll y Mehmet Akcakaya. "Physics-Driven Deep Learning for Computational Magnetic Resonance Imaging: Combining physics and machine learning for improved medical imaging". IEEE Signal Processing Magazine 40, n.º 1 (enero de 2023): 98–114. http://dx.doi.org/10.1109/msp.2022.3215288.

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21

Duan, Wenjuan, Guifang Liu, Cheng Guo y Yunhui Qu. "Preparation of Nano Materials Fe@Fe3O4 and Its Application in Magnetic Resonance Imaging for Liver Functions". Science of Advanced Materials 13, n.º 5 (1 de mayo de 2021): 906–16. http://dx.doi.org/10.1166/sam.2021.3994.

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The strengths of magnetic resonance imaging (MRI) lied in the strong penetrability, high resolution, no radiation, and non-invasion, while the sensitivity of MRI was too weak to distinguish the normal physiological tissue and pathological tissue. The contrast agent (CAs) was used to enhance the contrast ration of normal tissue and pathological tissue, and raise the precision of the diagnosis. The Ferric oxide with higher magnetic moment has been extensively applied in T2-weighted MRI contrast agents. In the study, the oil soluble nano materials (Fe@Fe3O4) was prepared, and its surface was modified using the large and small molecule ligands, and it was connected to F56 peptide, so as to construct the MRI-specific bimodal contrast agent (Fe–Fe NPs/HYA/F56). While the material was characterized, it can be used in clinical evaluation of liver functions. In the test, as the clad material was growing, the saturation magnetization of the material encountered a drop. The nano particle (Fe@Fe3O4) was modified with functional groups, and no obvious variation occurred to its structure and particle size. The morphology and potential were analyzed to confirm whether F56 peptide was connected to the nano particle (Fe@Fe3O4). The analysis of cell showed that the nano particle (Fe–Fe NPs/HYA/F56) had lower cytotoxicity, and the materials had better targeted performance, which had been verified in the mouse tumor model. The preparation materials were applied in evaluation of clinical studies on liver function. The quantitative analysis of the absolute enhancement value (AEV) and contrast enhancement rate (CER) of liver around the MRI-enhanced cancer was conducted. The results showed, the pathology grade of liver functions (pathological tissue and cirrhotic tissue) was related to the above indicators. The MRI contrast agent can be used to predict the pathology grade.

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22

Taleb-Ahmed, Abdelmalik. "Method to segment the brain automatically applied to a magnetic resonance imaging sequence". Optical Engineering 42, n.º 7 (1 de julio de 2003): 1976. http://dx.doi.org/10.1117/1.1580832.

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23

Chernoburova, Olga, Mathieu Jenny, Sébastien Kiesgen De Richter, Maude Ferrari y Akira Otsuki. "Dynamic Behavior of Dilute Bentonite Suspensions under Different Chemical Conditions Studied via Magnetic Resonance Imaging Velocimetry". Colloids and Interfaces 2, n.º 4 (27 de septiembre de 2018): 41. http://dx.doi.org/10.3390/colloids2040041.

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This study investigates dilute aqueous suspensions of bentonite particles using magnetic resonance imaging (MRI) velocimetry. Four different chemical conditions are tested to investigate the influence of pH and type of monovalent electrolyte on the local rheological behavior of bentonite suspensions. The results indicate the shear banding in a dilute suspension of 0.1 vol.% solid due to the formation of a continuous three-dimensional particle network under a certain chemical environment (i.e., pH 4 in 1 × 10−2 M KNO3). This network is responsible for the existence of the yield stress in that dilute suspension. Structural changes induced by modification of suspensions’ chemistry are examined via scanning electron microscopy. A previously established method based on processing the torques acquired via conventional rheometric measurement is also applied as an alternative way to recover local flow information. Within the shear rate range covered by our MRI velocimetry, the results of both methods show good agreement. This study suggests that the existence of a master curve (or global flow curve) for dilute suspensions is dependent on the bentonite particle organization, which is influenced by the suspension chemistry and the previous flow history.

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24

Jansons, Kalvis M. y Daniel C. Alexander. "Persistent angular structure: new insights from diffusion magnetic resonance imaging data". Inverse Problems 19, n.º 5 (22 de agosto de 2003): 1031–46. http://dx.doi.org/10.1088/0266-5611/19/5/303.

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25

Bringout, Gaël, Wolfgang Erb y Jürgen Frikel. "A new 3D model for magnetic particle imaging using realistic magnetic field topologies for algebraic reconstruction". Inverse Problems 36, n.º 12 (1 de diciembre de 2020): 124002. http://dx.doi.org/10.1088/1361-6420/abb446.

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26

Wróblewski, Przemysław y Waldemar Smolik. "COIL DESIGN WITH LITZE WIRE FOR MAGNETIC PARTICLE SPECTROMETRY". Informatics Control Measurement in Economy and Environment Protection 7, n.º 1 (30 de marzo de 2017): 0. http://dx.doi.org/10.5604/01.3001.0010.4605.

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The design of an excitation coil for magnetic particles spectrometer (MPS) was described. It was assumed that the spectrometer should measure the spectra of particles of diameter in the range 10-100 nm. To measure the amplitude and phase angle spectra of magnetic nanoparticles it is required to generate sinusoidal alternating spatially homogeneous magnetic field of magnitude of 20 mT. The work volume of the designed spectrometer was 202020 mm allowing measurement of small samples. The estimation of magnetic properties of magnetic nanoparticles is crucial in Magnetic Particles Imaging. In this paper we described the excitation coil design which minimizes power losses on the coil related to heat emission. The resonance circuit operating on 20 kHz frequency was applied. Optimal litze wire configuration was proposed to negate skin and proximity effects. The numeric simulations for the optimal and commercially available suboptimal litze wire configurations were performed. The comparison of the results was shown and discussed.

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27

Wu, Zekun, Zhen Chai, Yunkai Mao, Hao Tian y Zhanchao Liu. "High-resolution optical magnetic resonance imaging of electronic spin polarization in miniaturized atomic sensors". Applied Physics Letters 121, n.º 20 (14 de noviembre de 2022): 204103. http://dx.doi.org/10.1063/5.0106964.

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Miniaturized atomic sensors of magnetic field and inertia have great potential to be applied as geophysical instruments and in the detection of biomolecules. The distribution of the electronic spin polarization plays a key role as it defines the amount of noble gas that can achieve a state of hyperpolarization, which in turn determines the technique's accuracy and, consequently, its resolution. However, the current techniques for electronic spin polarization imaging are unsuited for the operating conditions of miniaturized atomic sensors besides only accomplishing submillimeter spatial resolution. In this study, optical magnetic resonance is applied to obtain electronic spin polarization images with a spatial resolution of 60 μm experimentally and 10 μm theoretically. This corresponds to an increase by one order of magnitude in resolution when compared to previous reports of electronic spin polarization imaging. By sweeping the RF frequency of the magnetic field while applying a magnetic field gradient of 0.22 [Formula: see text], it is possible to measure electronic spin polarization images for different average photon spins and pump beam positions. Spin polarization images present a high degree of correlation with pump beam images. Furthermore, this image method can be applied to suppressing the inhomogeneities in miniaturized cells, leading to a gain in signal-to-noise ratio. It also offers an opportunity to experimentally perform two-dimensional atomic polarization manipulation in the gas phase, optically transparent solids, and liquids.

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28

Kluth, Tobias, Bangti Jin y Guanglian Li. "On the degree of ill-posedness of multi-dimensional magnetic particle imaging". Inverse Problems 34, n.º 9 (17 de julio de 2018): 095006. http://dx.doi.org/10.1088/1361-6420/aad015.

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29

Luchetti, Alessandro, Davide Milani, Francesca Ruffini, Rossella Galli, Andrea Falini, Angelo Quattrini, Giuseppe Scotti et al. "Monoclonal Antibodies Conjugated with Superparamagnetic Iron Oxide Particles Allow Magnetic Resonance Imaging Detection of Lymphocytes in the Mouse Brain". Molecular Imaging 11, n.º 2 (1 de marzo de 2012): 7290.2011.00032. http://dx.doi.org/10.2310/7290.2011.00032.

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We investigated the potential of antibody-vectorialized superparamagnetic iron oxide (SPIO) particles as cellular specific magnetic resonance contrast agents to image lymphocyte populations within the central nervous system (CNS), with the final goal of obtaining a reliable tool for noninvasively detecting and tracking specific cellular populations in vivo. We used superparamagnetic particles bound to a monoclonal antibody. The particle is the contrast agent, by means of its T2* relaxation properties; the antibody is the targeting vector, responsible for homing the particle to target a surface antigen. To investigate the efficiency of particle vectorialization by these antibodies, we compared two types of antibody-vectorialized CD3-specific particles in vivo. We successfully employed vectorialized SPIO particles to image B220+ cells in a murine model of B-cell lymphoma. Likewise, we were able to identify CD3+ infiltrates in a murine model of multiple sclerosis. The specificity of the technique was confirmed by immunohistochemistry and electron microscopy of corresponding sections. Our findings suggest that indirect binding of the antibody to a streptavidinated particle allows for enhanced particle vectorialization compared to covalent binding of the antibody to the particle.

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30

Qi, Xinxin, Ming Yao, Mei Jin y Haoyou Guo. "Application of Magnetic Resonance Imaging Based on Fe3O4 Nanoparticles in the Treatment of Cerebrovascular Diseases". Journal of Nanoscience and Nanotechnology 21, n.º 2 (1 de febrero de 2021): 843–51. http://dx.doi.org/10.1166/jnn.2021.18697.

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Due to its high stability and excellent performance, inorganic nanomaterials have attracted much attention in the research of disease diagnosis and treatment. Focusing on inorganic nanomaterials, high-temperature pyrolysis has been used to successfully prepare Fe3O4 nanoparticles with different particle sizes. The diagnosis and treatment of Alzheimer’s disease have advanced, and many new diagnostic methods have been adopted clinically. In this paper, Fe3O4 nanoparticle magnetic resonance imaging technology is used to explore the application of magnetic Fe3O4 inorganic nanomaterials in cerebrovascular diseases in vivo. The results show that SWI has higher sensitivity and semi-quantitative advantages than traditional T2WI imaging technology. With different critical SWI concentrations, this article lays the experimental foundation for the clinical progress of inorganic nanomaterials and plays an important role in the treatment of cerebrovascular diseases.

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31

Bhalodiya, Jayendra M., Sarah N. Lim Choi Keung y Theodoros N. Arvanitis. "Magnetic resonance image-based brain tumour segmentation methods: A systematic review". DIGITAL HEALTH 8 (enero de 2022): 205520762210741. http://dx.doi.org/10.1177/20552076221074122.

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Background Image segmentation is an essential step in the analysis and subsequent characterisation of brain tumours through magnetic resonance imaging. In the literature, segmentation methods are empowered by open-access magnetic resonance imaging datasets, such as the brain tumour segmentation dataset. Moreover, with the increased use of artificial intelligence methods in medical imaging, access to larger data repositories has become vital in method development. Purpose To determine what automated brain tumour segmentation techniques can medical imaging specialists and clinicians use to identify tumour components, compared to manual segmentation. Methods We conducted a systematic review of 572 brain tumour segmentation studies during 2015–2020. We reviewed segmentation techniques using T1-weighted, T2-weighted, gadolinium-enhanced T1-weighted, fluid-attenuated inversion recovery, diffusion-weighted and perfusion-weighted magnetic resonance imaging sequences. Moreover, we assessed physics or mathematics-based methods, deep learning methods, and software-based or semi-automatic methods, as applied to magnetic resonance imaging techniques. Particularly, we synthesised each method as per the utilised magnetic resonance imaging sequences, study population, technical approach (such as deep learning) and performance score measures (such as Dice score). Statistical tests We compared median Dice score in segmenting the whole tumour, tumour core and enhanced tumour. Results We found that T1-weighted, gadolinium-enhanced T1-weighted, T2-weighted and fluid-attenuated inversion recovery magnetic resonance imaging are used the most in various segmentation algorithms. However, there is limited use of perfusion-weighted and diffusion-weighted magnetic resonance imaging. Moreover, we found that the U-Net deep learning technology is cited the most, and has high accuracy (Dice score 0.9) for magnetic resonance imaging-based brain tumour segmentation. Conclusion U-Net is a promising deep learning technology for magnetic resonance imaging-based brain tumour segmentation. The community should be encouraged to contribute open-access datasets so training, testing and validation of deep learning algorithms can be improved, particularly for diffusion- and perfusion-weighted magnetic resonance imaging, where there are limited datasets available.

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32

Athalye, Vivek, Michael Lustig y Martin Uecker. "Parallel magnetic resonance imaging as approximation in a reproducing kernel Hilbert space". Inverse Problems 31, n.º 4 (20 de marzo de 2015): 045008. http://dx.doi.org/10.1088/0266-5611/31/4/045008.

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33

Kimmich, Rainer. "Multidimensional NQR: Imaging and Exchange Spectroscopy". Zeitschrift für Naturforschung A 51, n.º 5-6 (1 de junio de 1996): 330–36. http://dx.doi.org/10.1515/zna-1996-5-604.

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Abstract In this context a ‘‘dimension’’ can be of a spatial or of a spectroscopic nature. In the last two decades, multidimensional nuclear magnetic resonance and imaging have proven to be most useful tools for the investigation of materials. It turned out that some of these measuring principles can be applied to zero-field NQR as well. The purpose of this presentation is to elucidate two-dimensional exchange spectroscopy and imaging procedures suitable for NQR and to outline potential applications.

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34

Bonnard, Bernard, Steffen J. Glaser y Dominique Sugny. "A Review of Geometric Optimal Control for Quantum Systems in Nuclear Magnetic Resonance". Advances in Mathematical Physics 2012 (2012): 1–29. http://dx.doi.org/10.1155/2012/857493.

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We present a geometric framework to analyze optimal control problems of uncoupled spin 1/2 particles occurring in nuclear magnetic resonance. According to the Pontryagin's maximum principle, the optimal trajectories are solutions of a pseudo-Hamiltonian system. This computation is completed by sufficient optimality conditions based on the concept of conjugate points related to Lagrangian singularities. This approach is applied to analyze two relevant optimal control issues in NMR: the saturation control problem, that is, the problem of steering in minimum time a single spin 1/2 particle from the equilibrium point to the zero magnetization vector, and the contrast imaging problem. The analysis is completed by numerical computations and experimental results.

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35

Knopp, T., M. Erbe, T. F. Sattel, S. Biederer y T. M. Buzug. "A Fourier slice theorem for magnetic particle imaging using a field-free line". Inverse Problems 27, n.º 9 (29 de julio de 2011): 095004. http://dx.doi.org/10.1088/0266-5611/27/9/095004.

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36

Erb, W., A. Weinmann, M. Ahlborg, C. Brandt, G. Bringout, T. M. Buzug, J. Frikel et al. "Mathematical analysis of the 1D model and reconstruction schemes for magnetic particle imaging". Inverse Problems 34, n.º 5 (20 de abril de 2018): 055012. http://dx.doi.org/10.1088/1361-6420/aab8d1.

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37

Kluth, Tobias. "Erratum for Mathematical models for magnetic particle imaging (2018 Inverse Problems 34 083001)". Inverse Problems 36, n.º 3 (11 de febrero de 2020): 039601. http://dx.doi.org/10.1088/1361-6420/ab5483.

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38

Stueber, Deanna D., Jake Villanova, Itzel Aponte, Zhen Xiao y Vicki L. Colvin. "Magnetic Nanoparticles in Biology and Medicine: Past, Present, and Future Trends". Pharmaceutics 13, n.º 7 (24 de junio de 2021): 943. http://dx.doi.org/10.3390/pharmaceutics13070943.

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The use of magnetism in medicine has changed dramatically since its first application by the ancient Greeks in 624 BC. Now, by leveraging magnetic nanoparticles, investigators have developed a range of modern applications that use external magnetic fields to manipulate biological systems. Drug delivery systems that incorporate these particles can target therapeutics to specific tissues without the need for biological or chemical cues. Once precisely located within an organism, magnetic nanoparticles can be heated by oscillating magnetic fields, which results in localized inductive heating that can be used for thermal ablation or more subtle cellular manipulation. Biological imaging can also be improved using magnetic nanoparticles as contrast agents; several types of iron oxide nanoparticles are US Food and Drug Administration (FDA)-approved for use in magnetic resonance imaging (MRI) as contrast agents that can improve image resolution and information content. New imaging modalities, such as magnetic particle imaging (MPI), directly detect magnetic nanoparticles within organisms, allowing for background-free imaging of magnetic particle transport and collection. “Lab-on-a-chip” technology benefits from the increased control that magnetic nanoparticles provide over separation, leading to improved cellular separation. Magnetic separation is also becoming important in next-generation immunoassays, in which particles are used to both increase sensitivity and enable multiple analyte detection. More recently, the ability to manipulate material motion with external fields has been applied in magnetically actuated soft robotics that are designed for biomedical interventions. In this review article, the origins of these various areas are introduced, followed by a discussion of current clinical applications, as well as emerging trends in the study and application of these materials.

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39

Kharauzov, A. K., P. P. Vasil’ev, A. V. Sokolov, V. A. Fokin y Yu E. Shelepin. "Functional magnetic resonance imaging analysis of the human brain in texture recognition tasks". Journal of Optical Technology 85, n.º 8 (1 de agosto de 2018): 463. http://dx.doi.org/10.1364/jot.85.000463.

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40

Arduino, Alessandro, Oriano Bottauscio, Mario Chiampi y Luca Zilberti. "Magnetic resonance-based imaging of human electric properties with phaseless contrast source inversion". Inverse Problems 34, n.º 8 (11 de junio de 2018): 084002. http://dx.doi.org/10.1088/1361-6420/aac536.

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41

Savukov, Igor, Young Jin Kim y Shaun Newman. "High-resolution ultra-low field magnetic resonance imaging with a high-sensitivity sensing coil". Journal of Applied Physics 132, n.º 17 (7 de noviembre de 2022): 174503. http://dx.doi.org/10.1063/5.0123692.

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We present high-resolution magnetic resonance imaging (MRI) at ultra-low field (ULF) with a proton Larmor frequency of around 120 kHz. The key element is a specially designed high-sensitivity sensing coil in the shape of a solenoid with a few millimeter gap between windings to decrease the proximity effect and, hence, increase the coil’s quality ([Formula: see text]) factor and sensitivity. External noise is strongly suppressed by enclosing the sensing coil in a copper cylindrical shield, large enough not to negatively affect the coil’s [Formula: see text] factor and sensitivity, measured to be 217 and 0.47 fT/Hz[Formula: see text], respectively. To enhance small polarization of proton spins at ULF, a strong pulsed 0.1 T prepolarization field is applied, making the signal-to-noise ratio (SNR) of ULF MRI sufficient for high-quality imaging in a short time. We demonstrate ULF MRI of a copper sulfate solution phantom with a resolution of [Formula: see text] and SNR of 10. The acquisition time is 6.3 min without averaging. The sensing coil size in the current realization can accommodate imaging objects of 9 cm in size, sufficient for hand, and it can be further increased for human head imaging in the future. Since the in-plane resolution of [Formula: see text] is typical in anatomical medical imaging, this ULF MRI method can be an alternative low-cost, rapid, portable method for anatomical medical imaging of the human body or animals. This ULF MRI method can supplement other MRI methods, especially when such methods are restricted due to high cost, portability requirement, imaging artifacts, and other factors.

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42

Nguyen, Dang Van, Jing-Rebecca Li, Denis Grebenkov y Denis Le Bihan. "A finite elements method to solve the Bloch–Torrey equation applied to diffusion magnetic resonance imaging". Journal of Computational Physics 263 (abril de 2014): 283–302. http://dx.doi.org/10.1016/j.jcp.2014.01.009.

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43

Kim, Doohyeon, Jihun Kang, Ehsan Adeeb, Gyu-Han Lee, Dong Hyun Yang y Hojin Ha. "Comparison of Four-Dimensional Flow Magnetic Resonance Imaging and Particle Image Velocimetry to Quantify Velocity and Turbulence Parameters". Fluids 6, n.º 8 (6 de agosto de 2021): 277. http://dx.doi.org/10.3390/fluids6080277.

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Although recent advances of four-dimensional (4D) flow magnetic resonance imaging (MRI) has introduced a new way to measure Reynolds stress tensor (RST) in turbulent flows, its measurement accuracy and possible bias have remained to be revealed. The purpose of this study was to compare the turbulent flow measurement of 4D flow MRI and particle image velocimetry (PIV) in terms of velocity and turbulence quantification. Two difference flow rates of 10 and 20 L/min through a 50% stenosis were measured with both PIV and 4D flow MRI. Not only velocity through the stenosis but also the turbulence parameters such as turbulence kinetic energy and turbulence production were quantitatively compared. Results shows that 4D flow MRI velocity measurement well agreed with the that of PIV, showing the linear regression slopes of two methods are 0.94 and 0.89, respectively. Although turbulence mapping of 4D flow MRI was qualitatively agreed with that of PIV, the quantitative comparison shows that the 4D flow MRI overestimates RST showing the linear regression slopes of 1.44 and 1.66, respectively. In this study, we demonstrate that the 4D flow MRI visualize and quantify not only flow velocity and also turbulence tensor. However, further optimization of 4D flow MRI for better accuracy might be remained.

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44

Yi, Xianghua, Yongmei Ding, Yu Zeng, Caicun Zhou, Benfang Luo, Shuyan Meng, Weiwei Rui, Yinmin Zhao y Wei Li. "Magnetic Resonance Imaging Contrast Agent: cRGD-Ferric Oxide Nanometer Particle and Its Role in the Diagnosis of Tumor". Journal of Nanoscience and Nanotechnology 11, n.º 5 (1 de mayo de 2011): 3800–3807. http://dx.doi.org/10.1166/jnn.2011.3861.

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45

Schier, Peter, Maik Liebl, Uwe Steinhoff, Michael Handler, Frank Wiekhorst y Daniel Baumgarten. "Optimizing Excitation Coil Currents for Advanced Magnetorelaxometry Imaging". Journal of Mathematical Imaging and Vision 62, n.º 2 (17 de diciembre de 2019): 238–52. http://dx.doi.org/10.1007/s10851-019-00934-8.

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AbstractMagnetorelaxometry imaging is a highly sensitive technique enabling noninvasive, quantitative detection of magnetic nanoparticles. Electromagnetic coils are sequentially energized, aligning the nanoparticles’ magnetic moments. Relaxation signals are recorded after turning off the coils. The forward model describing this measurement process is reformulated into a severely ill-posed inverse problem that is solved for estimating the particle distribution. Typically, many activation sequences employing different magnetic fields are required to obtain reasonable imaging quality. We seek to improve the imaging quality and accelerate the imaging process using fewer activation sequences by optimizing the applied magnetic fields. Minimizing the Frobenius condition number of the system matrix, we stabilize the inverse problem solution toward model uncertainties and measurement noise. Furthermore, our sensitivity-weighted reconstruction algorithms improve imaging quality in lowly sensitive areas. The optimization approach is employed to real measurement data and yields improved reconstructions with fewer activation sequences compared to non-optimized measurements.

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46

Nunes, Teresa G. "Influence of Grain Size on the Setting of Portland Cement: A Stray-Field Magnetic Resonance Imaging Study". Materials Science Forum 514-516 (mayo de 2006): 1633–37. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1633.

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A number of failures of large concrete structures during construction have been reported in the last decades [1]. The overestimation of concrete strength at early ages was one of the reasons for the failures. Consequently, reliable information about early age properties of the material is essential to guarantee life-time performance of structures. Portland cement is a complex heterogeneous particulate material and a full knowledge of kinetics of the hydration reactions, for example, is still missing. Gel constitutes the major phase in the hardening cement paste and the corresponding structure and dynamics represent an important contribution to determine the concrete performance. X-ray diffraction, which is widely used for the study of crystalline cement components, does not give information about the gel, amorphous, phase. Conversely, 1H stray-field magnetic resonance imaging (STRAFI-MRI) technique has proved to be a powerful tool to follow the early hydration and hardening periods of Portland cement (type I) [2-4]. The setting of cement pastes depends on parameters like the initial water/cement ratio, R, or particle size of the powder (G) and the compressive strength can be used to characterize the behaviour of hardening concrete. Water availability at the particle surfaces, which is controlled by R and G, limits cement hydration. At low R, G effects are less important. In general, it is accepted that for R<0.42, unreacted solid remain, as all the free volume is filled with hydration products [5]. For example, hydration of Portland cement pastes as a function of R (0.24-0.48) was studied using by STRAFI-MRI and hydrogen maps, from different types of water (capillary, gel or chemically bound water), enabled a spatially-resolved kinetics to be obtained [4]. Using STRAFI-MRI was now evaluated the influence of G (<70 μm to < 90 μm) on the early stages of hydration and hardening of Portland cement. Portland cement uses extend well beyond construction. For example, a mineral trioxide aggregate is now being applied as a root-end filling material, which was shown to have a similar chemical constitution to that of Portland cement except for the addition of bismuth compounds, seemingly to make the materials radiopaque for dental use [6].

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47

Senior, A. y F. Honary. "Observations of the spatial structure of electron precipitation pulsations using an imaging riometer". Annales Geophysicae 21, n.º 4 (30 de abril de 2003): 997–1003. http://dx.doi.org/10.5194/angeo-21-997-2003.

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Abstract. Electron precipitation can be modulated by geomagnetic pulsation activity. This can be observed as pulsation of cosmic noise absorption as measured by riometers. Observations of such pulsations exhibiting field-line resonance and particle-driven characteristics using an imaging riometer are presented and the capability of the instrument to map their spatial structure is demonstrated. It is shown that for the events studied, the spatial variation of pulsation phase as measured by the riometer agrees with that inferred from ground-based magnetometers, whereas the spatial variation of pulsation amplitude may show a different structure. It is suggested that this is consistent with the mechanism proposed by Coroniti and Kennel (1970) where one would expect a fixed phase relationship between magnetic and absorption pulsations, but where the amplitude of the absorption pulsation can depend on several factors other than the amplitude of the magnetic pulsation.Key words. Ionosphere (ionosphere–magnetosphere interactions; particle precipitation) – Magnetospheric physics (MHD waves and instabilities)

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48

Wu, Yuli, Junwei Song, Shengcui Liu, Xianglei Wei y Weiwei Chen. "Application of Gold Nanoparticles in Magnetic Resonance Imaging for Targeted Diagnosis and Treatment of Breast Cancer". Science of Advanced Materials 13, n.º 9 (1 de septiembre de 2021): 1595–602. http://dx.doi.org/10.1166/sam.2021.4062.

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This study aimed to explore the application of super paramagnetic gold magnetic nanoparticles (Au-M-NPs) in the magnetic resonance imaging (MRI) images for targeted diagnosis and treatment of breast cancer. The reducibility of ethylene glycol to ferric chloride (FeCl3) was adopted to synthesize the Au-M-NPs by solvothermal method by taking acetic acid as the base source and trisodium citrate as the stabilizer. Besides, the synthesized Au-M-NPs were applied in the MRI images for targeted therapy of breast cancer. Patients from a blank group (group A), a control group (group B), and an experimental group (group C) received the traditional clinical diagnosis treatment, MRI diagnosis, and Au-M-NPs targeted therapy with MRI in turn. The results showed that the prepared Au-M-NPs were featured with small particle size and good dispersibility, and were monodispersive after surface modification. The intraoperative blood loss of patients from group A (115.3±9.33 mL) and group B (94.6±9.72 mL) was obviously higher than the loss of group C (68.4±8.7 mL) (P < 0.05). The drainage volume of patients from group B (162.4±12.3 mL) and group C (131.9±11.8 mL) decreased sharply after surgery compared with group A (193.7±11.8 mL), and that in group C was the lowest (P < 0.05). The proportion of local recurrence in patients from group B (12.3%) and group C (6.4%) dropped steeply in contrast to the proportion of group A (13.2%) (P < 0.05). The proportion of tumor metastasis in patients from group B (11.2%) and group C (8.4%) was greatly lower than that of group A (14.8%) (P < 0.05). In conclusion, the application of Au-M-NPs in the diagnosis and treatment of breast cancer with MRI could effectively reduce the incidence of intraoperative and postoperative adverse reactions.

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49

Budnyk, A. P., T. A. Lastovina, A. L. Bugaev, V. A. Polyakov, K. S. Vetlitsyna-Novikova, M. A. Sirota, K. G. Abdulvakhidov, A. G. Fedorenko, E. O. Podlesnaya y A. V. Soldatov. "Gd3+-Doped Magnetic Nanoparticles for Biomedical Applications". Journal of Spectroscopy 2018 (2 de agosto de 2018): 1–9. http://dx.doi.org/10.1155/2018/1412563.

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Magnetic nanoparticles (MNPs) made of iron oxides with cubic symmetry (Fe3O4, γ-Fe2O3) are demanded objects for multipurpose in biomedical applications as contrast agents for magnetic resonance imaging, magnetically driven carriers for drug delivery, and heaters in hyperthermia cancer treatment. An optimum balance between the right particle size and good magnetic response can be reached by a selection of a synthesis method and by doping with rare earth elements. Here, we present a microwave-assisted polyol synthesis of iron oxide MNPs with actual gadolinium (III) doping from 0.5 to 5.1 mol.%. The resulting MNPs have an average size of 14 nm with narrow size distribution. Their surface was covered by a glycol layer, which prevents aggregation and improves biocompatibility. The magnetic hyperthermia test was performed on 1 and 2 mg/ml aqueous colloidal solutions of MNPs and demonstrated their ability to rise the temperature by 3°C during a 20–30 min run. Therefore, the obtained Gd3+ MNPs are the promising material for biomedicine.

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50

Chang, Catie, Erika P. Raven y Jeff H. Duyn. "Brain–heart interactions: challenges and opportunities with functional magnetic resonance imaging at ultra-high field". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, n.º 2067 (13 de mayo de 2016): 20150188. http://dx.doi.org/10.1098/rsta.2015.0188.

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Magnetic resonance imaging (MRI) at ultra-high field (UHF) strengths (7 T and above) offers unique opportunities for studying the human brain with increased spatial resolution, contrast and sensitivity. However, its reliability can be compromised by factors such as head motion, image distortion and non-neural fluctuations of the functional MRI signal. The objective of this review is to provide a critical discussion of the advantages and trade-offs associated with UHF imaging, focusing on the application to studying brain–heart interactions. We describe how UHF MRI may provide contrast and resolution benefits for measuring neural activity of regions involved in the control and mediation of autonomic processes, and in delineating such regions based on anatomical MRI contrast. Limitations arising from confounding signals are discussed, including challenges with distinguishing non-neural physiological effects from the neural signals of interest that reflect cardiorespiratory function. We also consider how recently developed data analysis techniques may be applied to high-field imaging data to uncover novel information about brain–heart interactions.

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