WorldWideScience

Sample records for magnetic resonance investigation

  1. Magnetic resonance: discovery, investigations, and applications

    International Nuclear Information System (INIS)

    Kessenikh, Aleksandr V

    2009-01-01

    The history of the development of the theoretical ideas and experimental methods of magnetic resonance, as well as the applications of these methods in modern natural science, technology, and medicine, are outlined, with allowance for the contribution of Russian researchers. An assessment of some promising trends of studies and applications of magnetic resonance is given. (from the history of physics)

  2. Magnetic resonance investigation of magnetic-labeled baker's yeast cells

    International Nuclear Information System (INIS)

    Godoy Morais, J.P.M.; Azevedo, R.B.; Silva, L.P.; Lacava, Z.G.M.; Bao, S.N.; Silva, O.; Pelegrini, F.; Gansau, C.; Buske, N.; Safarik, I.; Safarikova, M.; Morais, P.C.

    2004-01-01

    In this study, the interaction of DMSA-coated magnetite nanoparticles (5 and 10 nm core-size) with Saccharomyces cerevisae was investigated using magnetic resonance (MR) and transmission electron microscopy (TEM). The TEM micrographs revealed magnetite nanoparticles attached externally to the cell wall. The MR data support the strong interaction among the nanoparticles supported by the cells. A remarkable shift in the resonance field was used as signature of particle attachment to the cell wall

  3. Investigation of magnetic interactions in sulfides by means of magnetic resonance

    International Nuclear Information System (INIS)

    Veen, G. van.

    1978-01-01

    Investigations have been designed to gather more information about magnetic pair interactions in sulfides by isomorphic substitution of the magnetic ions in suitable chosen diamagnetic host lattices and measurement of electron spin resonance of coupled pairs and of electron spin resonance or electron nuclear double resonance of the hyperfine interaction due to the nuclei of diamagnetic cations. The greater part of this thesis is devoted to preliminaries of magnetic resonance interpretation and sample selection and preparation. The measurements on the magnetically diluted compounds, which are described, only have an exploratory nature. (Auth.)

  4. Magnetic resonance imaging and nuclear magnetic resonance investigations of bentonite systems

    Energy Technology Data Exchange (ETDEWEB)

    Dvinskikh, Sergey V.; Furo, Istvan (Industrial NMR Centre and Div. of Physical Chemistry, Dept. of Chemistry, Royal Institute of Technology, Stockholm (Sweden))

    2009-09-15

    This report summarizes results from a set of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) experiments performed on Ca and Na montmorillonite samples interacting with water. The primary goal with these studies was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during and after different physical processes such as swelling and sedimentation and on the time scale from minutes to years. Additionally, we also studied the distribution of foreign particles (such as native minerals as well as magnetic model particles) within bentonite systems and performed some diffusion NMR experiments with the aim of characterizing the state of colloids that form after clay dissolution. Both natural montmorillonites and purified and ion-exchanged montmorillonite clays were investigated. The primary variables were clay composition and water ionic strength. Bulk samples confined in a vertical tube and in a horizontal channel were investigated. A critical issue for the stability of clay buffer layer in deep underground repository is to prevent or minimize the release of clay particles into the water phase. In our experiments, the most significant particle losses were found for Na-MX80 clay exposed to water with low ionic strength. With increasing the concentration of CaCl{sub 2} in the water phase both swelling and particle release are slowed down but not completely eliminated due probably to gradual change of water ion content via ion exchange with the clay itself. For natural MX80 samples, in spite of significant swelling expansion, no clay particle release above the sensitivity limit of 0.001 volume% was observed. Ca-MX80 exhibited the smallest expansion and no trace of clay particle released into the aqueous phase

  5. Magnetic resonance imaging and nuclear magnetic resonance investigations of bentonite systems

    International Nuclear Information System (INIS)

    Dvinskikh, Sergey V.; Furo, Istvan

    2009-09-01

    This report summarizes results from a set of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) experiments performed on Ca and Na montmorillonite samples interacting with water. The primary goal with these studies was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during and after different physical processes such as swelling and sedimentation and on the time scale from minutes to years. Additionally, we also studied the distribution of foreign particles (such as native minerals as well as magnetic model particles) within bentonite systems and performed some diffusion NMR experiments with the aim of characterizing the state of colloids that form after clay dissolution. Both natural montmorillonites and purified and ion-exchanged montmorillonite clays were investigated. The primary variables were clay composition and water ionic strength. Bulk samples confined in a vertical tube and in a horizontal channel were investigated. A critical issue for the stability of clay buffer layer in deep underground repository is to prevent or minimize the release of clay particles into the water phase. In our experiments, the most significant particle losses were found for Na-MX80 clay exposed to water with low ionic strength. With increasing the concentration of CaCl 2 in the water phase both swelling and particle release are slowed down but not completely eliminated due probably to gradual change of water ion content via ion exchange with the clay itself. For natural MX80 samples, in spite of significant swelling expansion, no clay particle release above the sensitivity limit of 0.001 volume% was observed. Ca-MX80 exhibited the smallest expansion and no trace of clay particle released into the aqueous phase

  6. Electron magnetic resonance investigation of chromium diffusion in yttria powders

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, R.S. de, E-mail: rsbiasi@ime.eb.b [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, Pr. General Tiburcio, 80, 22290-270 Rio de Janeiro, RJ (Brazil); Grillo, M.L.N., E-mail: mluciag@uerj.b [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)

    2010-03-01

    The electron magnetic resonance (EMR) technique was used to investigate the diffusion of chromium in yttria (Y{sub 2}O{sub 3}) powders. The EMR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323 and 1373 K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be E{sub A}=342+-5 kJ mol{sup -1}. This value is larger than the activation energy for the diffusion of chromium in rutile (TiO{sub 2}), periclase (MgO) and cobalt monoxide (CoO) and smaller than the activation energy for the diffusion of chromium in chrysoberyl (BeAl{sub 2}O{sub 4}).

  7. Staging of nasopharyngeal carcinoma investigated by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Lu Jincheng; Wei Baoqing; Chen Wenzhan; Qian Pudong; Zhang Yiqin; Wei Qing; Cha Wenwu; Li Feng; Ni Ming

    2006-01-01

    Background and purpose: To investigate the American Joint Commission on Cancer (AJCC) sixth edition staging system of nasopharyngeal carcinoma (NPC) by Magnetic Resonance Imaging (MRI). Patients and methods: One hundred and fifty-nine non-disseminated biopsy-proven NPC patients were studied with MRI before treatment. Retrieval of MRI information enabled us to restage all patients accurately according to the sixth edition of the AJCC staging system. Splitting the respective T and N stages by the significant defining factors identified, the cancer death hazard ratios were modeled by the Cox model in SPSS 10.0 for windows (SPSS Inc, Chicago, IL). Results: Single site of skull base abnormality (HR=3.91, 95% CI: 0.74-20.56) has a superior result to others involved in T3 (HR=5.83, 95% CI: 1.24-27.29). Involvement of either anterior or posterior cranial nerves solely (HR=6.02, 95% CI: 1.55-35.60) was not found to be as a poor prognostic indicator as others involved in T4 (HR=7.81, 95% CI: 1.81-33.63). Less than or equal to 3 cm of N1 (HR=4.01, 95% CI: 0.48-33.83) and N2 (HR=4.72, 95% CI: 0.62-35.78) have a better result than >3 cm of N1 (HR=8.09, 95% CI: 0.95-68.97) and N2 (HR=10.58, 95% CI: 1.32-84.62), respectively. Conclusions: Perhaps, it is better to down-stage single site of skull base abnormality from T3 to T2, and involvement of either anterior or posterior cranial nerves solely from T4 to T3, meanwhile, ≤3 cm of N2 down-stage to N1, >3 cm of N1 up-stage to N2

  8. Magnetic resonance techniques for investigation of multiple sclerosis

    Science.gov (United States)

    MacKay, Alex; Laule, Cornelia; Li, David K. B.; Meyers, Sandra M.; Russell-Schulz, Bretta; Vavasour, Irene M.

    2014-11-01

    Multiple sclerosis (MS) is a common neurological disease which can cause loss of vision and balance, muscle weakness, impaired speech, fatigue, cognitive dysfunction and even paralysis. The key pathological processes in MS are inflammation, edema, myelin loss, axonal loss and gliosis. Unfortunately, the cause of MS is still not understood and there is currently no cure. Magnetic resonance imaging (MRI) is an important clinical and research tool for MS. 'Conventional' MRI images of MS brain reveal bright lesions, or plaques, which demark regions of severe tissue damage. Conventional MRI has been extremely valuable for the diagnosis and management of people who have MS and also for the assessment of therapies designed to reduce inflammation and promote repair. While conventional MRI is clearly valuable, it lack pathological specificity and, in some cases, sensitivity to non-lesional pathology. Advanced MR techniques have been developed to provide information that is more sensitive and specific than what is available with clinical scanning. Diffusion tensor imaging and magnetization transfer provide a general but non-specific measure of the pathological state of brain tissue. MR spectroscopy provides concentrations of brain metabolites which can be related to specific pathologies. Myelin water imaging was designed to assess brain myelination and has proved useful for measuring myelin loss in MS. To combat MS, it is crucial that the pharmaceutical industry finds therapies which can reverse the neurodegenerative processes which occur in the disease. The challenge for magnetic resonance researchers is to design imaging techniques which can provide detailed pathological information relating to the mechanisms of MS therapies. This paper briefly describes the pathologies of MS and demonstrates how MS-associated pathologies can be followed using both conventional and advanced MR imaging protocols.

  9. Solid state nuclear magnetic resonance investigations of advanced energy materials

    Science.gov (United States)

    Bennett, George D.

    In order to better understand the physical electrochemical changes that take place in lithium ion batteries and asymmetric hybrid supercapacitors solid state nuclear magnetic resonance (NMR) spectroscopy has been useful to probe and identify changes on the atomic and molecular level. NMR is used to characterize the local environment and investigate the dynamical properties of materials used in electrochemical storage devices (ESD). NMR investigations was used to better understand the chemical composition of the solid electrolyte interphase which form on the negative and positive electrodes of lithium batteries as well as identify the breakdown products that occur in the operation of the asymmetric hybrid supercapacitors. The use of nano-structured particles in the development of new materials causes changes in the electrical, structural and other material properties. NMR was used to investigate the affects of fluorinated and non fluorinated single wall nanotubes (SWNT). In this thesis three experiments were performed using solid state NMR samples to better characterize them. The electrochemical reactions of a lithium ion battery determine its operational profile. Numerous means have been employed to enhance battery cycle life and operating temperature range. One primary means is the choice and makeup of the electrolyte. This study focuses on the characteristics of the solid electrolyte interphase (SEI) that is formed on the electrodes surface during the charge discharge cycle. The electrolyte in this study was altered with several additives in order to determine the influence of the additives on SEI formation as well as the intercalation and de-intercalation of lithium ions in the electrodes. 7Li NMR studies where used to characterize the SEI and its composition. Solid state NMR studies of the carbon enriched acetonitrile electrolyte in a nonaqueous asymmetric hybrid supercapacitor were performed. Magic angle spinning (MAS) coupled with cross polarization NMR

  10. An investigation of cerebral magnetic resonance angiography, 5

    International Nuclear Information System (INIS)

    Takeda, Sadanori; Sadamoto, Kazuhiko; Ohue, Shiro; Todo, Hirooki; Sakaki, Saburo.

    1992-01-01

    A number of studies of MR angiography (MRA) as a noninvasive screening method for vascular diseases have been reported recently. Almost all of them were investigated using high tesla magnets (1.5 tesla). We have been investigating three-dimensional MRA using a medium tesla (0.5 tesla) system (HITACHI G-50). The purpose of this study is to evaluate the usefulness of 3-D MRA for the screening of cerebral aneurysms. Twenty patients with 25 cerebral aneurysms were included in this study. The sizes of the aneurysms ranged from 2 to 35 mm. Twenty-three aneurysms were located on the anterior circulation, and 2 on the posterior circulation. MR angiography was performed with a gradient-echo sequence at a TR of 50 msec, a TE of 16 msec, and a flip angle of 25 degrees. The imaging volumes ranged in thickness from 48 to 64 mm, with 32 partitions. We used a sequence-subtraction technique composed of rephased and dephased sequences; it provides a good visualization of the main cerebral arteries. Cerebral aneurysms were detected on 3-D MRA in 23 lesions (92%). We consider that 0.5 tesla 3-D MRA could be useful for the screening of nonruptured aneurysms. (author)

  11. Magnetic resonance annual 1986

    International Nuclear Information System (INIS)

    Kressel, H.Y.

    1986-01-01

    This book contains papers written on magnetic resonance during 1986. Topics include: musculosketetal magnetic resonance imaging; imaging of the spine; magnetic resonance chemical shift imaging; magnetic resonance imaging in the central nervous system; comparison to computed tomography; high resolution magnetic resonance imaging using surface coils; magnetic resonance imaging of the chest; magnetic resonance imaging of the breast; magnetic resonance imaging of the liver; magnetic resonance spectroscopy of neoplasms; blood flow effects in magnetic resonance imaging; and current and potential applications of clinical sodium magnetic resonance imaging

  12. Hepatic Metabolism of Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in vito

    Science.gov (United States)

    1994-01-06

    L. Narayanan. and B. M. Jamot. ’Effects of Peulluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic Phosphorus Metabolism in...pathways and examined the impact of perfluorocarboxylic acid exposure. This investigative strategy will delineate the metabolic effices exerted by...Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in Vivo Principal Investigator: Nicholas V. Reo

  13. Induced magnetism at the interfaces of a Fe/V superlattice investigated by resonant magnetic x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Magnuson, Martin, E-mail: Martin.Magnuson@ifm.liu.se

    2017-01-15

    The induced magnetic moments in the V 3d electronic states of interface atomic layers in a Fe(6ML)/V(7ML) superlattice was investigated by x-ray resonant magnetic scattering. The first V atomic layer next to Fe was found to be strongly antiferromagnetically polarized relatively to Fe and the magnetic moments of the next few atomic layers in the interior V region decay exponentially with increasing distance from the interface, while the magnetic moments of the Fe atomic layers largely remain bulk-like. The induced V moments decay more rapidly as observed by x-ray magnetic scattering than in standard x-ray magnetic circular dichroism. The theoretical description of the induced magnetic atomic layer profile in V was found to strongly rely on the interface roughness within the superlattice period. These results provide new insight into interface magnetism by taking advantage of the enhanced depth sensitivity to the magnetic profile over a certain resonant energy bandwidth in the vicinity of the Bragg angles. - Highlights: • Magnetic moments of buried layers are probed by XRMS in a Fe/V superlattice. • The induced V magnetic moments in XRMS are more rapidly decaying than previously observed by XMCD. • The magnetic depth profile sensitivity is enhanced at an energy bandwidth in the vicinity of the Bragg angles.

  14. Investigation of Condensed Media in Weak Fields by the Method of Nuclear Magnetic Resonance

    Science.gov (United States)

    Davydov, V. V.; Myazin, N. S.; Dudkin, V. I.; Velichko, E. N.

    2018-05-01

    A compact design of a rapid-response nuclear magnetic spectrometer for investigation of condensed media in weak fields is reported. As a result of investigation of different condensed media, special features of recording a nuclear magnetic resonance (NMR) signal in a weak magnetic field from a small volume of the medium under study are established. For the first time the NMR absorption spectra of condensed media in a weak field are collected. Based on the results of experimental studies, the potential of using a compact NMR-spectrometer for condensed media monitoring in a rapid response mode is determined.

  15. Nuclear magnetic resonance structure investigations on crosslinked polyesters

    International Nuclear Information System (INIS)

    Grobelny, J.

    1999-01-01

    Styrene-crosslinked mixed polyesters derived from maleic anhydride, 2,2-di(4-hydroxypropoxyphenyl)propane, oligo(propylene oxide) and 1,2-propylene glycol were investigated by high-resolution solid-state 13 C NMR spectroscopy. The structural modifications accompanying crosslinking were characterized in terms of spin-lattice relaxation times as a function of unsaturated polyester composition. Copolymerization and crosslinking effects were individually evaluated and the latter effect was related to variations in crosslinking density associated with the chemical structure of the unsaturated prepolymer. As the crosslinking effect is suppressed, the mechanical properties undergo expected changes, e.g., impact strength is increased and modulus of elasticity in tension is decreased. (author)

  16. MRI (Magnetic Resonance Imaging)

    Science.gov (United States)

    ... Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Magnetic Resonance Imaging (MRI) is a medical imaging procedure for ...

  17. Hepatic Metabolism of Perfluorinated Carboxylic Acids and Polychlorotrifluoroethylene: A Nuclear Magnetic Resonance Investigation in Vivo

    Science.gov (United States)

    1994-01-05

    Goecke, L. Narayanan, and B. M. Jarnot. "Effects of Perfluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic Phosphorus L...Carboxylic Acids and 4Polychiorotrifluoroethylene: A Nuclear Magnetic Resonance G-AFOSR-90-0148 Investigation in Vivo ,IIC 6. AUTHOR(S a Nicholas V. Reo...Maxim um 200 words) This report outlines our research progress regarding toxicological investigations of perifluoro- n-octanoic acid (PFOA) and

  18. Ferromagnetic resonance investigation in permalloy magnetic antidot arrays on alumina nanoporous membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Suárez, R.L., E-mail: rrodriguez@fis.puc.cl [Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860 Casilla 306, Santiago (Chile); Palma, J.L.; Burgos, E.O. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Michea, S. [Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860 Casilla 306, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J.; Denardin, J.C. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Aliaga, C. [Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago (Chile)

    2014-01-15

    The magnetic properties of Ni{sub 80}Fe{sub 20} antidot arrays with hole diameters of 18 and 70 nm fabricated by a template-assisted method were investigated using the ferromagnetic resonance technique. Tuning the antidot arrays by changing the hole diameter enables control on the angular dependence of the ferromagnetic resonance field. The scanning electron microscope images reveal a quite regular hexagonal arrangement of the pores, however the angular dependence of the resonance field do not exhibit the six-fold symmetry expected for this symmetry. Micromagnetic simulations performed on a perfect hexagonal lattice, when compared with those made on our real system taken from the scanning microscope images, reveal that the presence of defects in the antidot lattice affects the ferromagnetic resonance field symmetry. - Highlights: • We use the FMR technique to investigate the magnetic properties of Py antidots. • We studied the effect of pore diameter on FMR angular measurement. • FMR field does not exhibit the six-fold symmetry. • For all angular positions there are two resonance modes always present. • Micromagnetic simulations agree with the experimental results with defects.

  19. Hepatic Metabolism of Perfluorinated Carboxylic Acids: A Nuclear Magnetic Resonance Investigation in Vivo

    Science.gov (United States)

    1995-01-17

    Reo, C. M. Goecke, L. Narayanan, and B. M. Jarnot. "Effects of Perfluoro-n- octanoic Acid , Perfluoro-n-decanoic Acid , and Clofibrate on Hepatic...SUBTITLE 7C 5. FUNDING NUMBERS" Hepatic Metabolism of Perfluorinated Carboxylic Acids : A Nuclear Magnetic Resonance Investigation in Vivo G-AFOSR-90-0148 6...octanoic acid (PFOA) and perfluoro-n-decanoic acid (PFDA). These Air Force chemicals belong to a class of CU’. compounds known as peroxisome

  20. Magnetic resonance imaging

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    Magnetic resonance imaging (MRI) is a new and innovative technique that affords anatomic images in multiple planes and that may provide information about tissue characterization. The magnetic resonance images are obtained by placing the patient or the area of interest within a powerful, highly uniform, static magnetic field. Magnetized protons (hydrogen nuclei) within the patient align like small magnets in this field. Radiofrequency pulses are then used to create an oscillating magnetic field perpendicular to the main field. Magnetic resonance images differ from those produced by x-rays: the latter are associated with absorption of x-ray energy while magnetic resonance images are based on proton density and proton relaxation dynamics. Proton characteristics vary according to the tissue under examination and reflect its physical and chemical properties. To resolve issues regarding safety and efficacy, the Warren Grant Magnuson Clinical Center and the Office of Medical Applications of Research of the National Institutes of Health (NIH) convened a consensus conference about MRI Oct 26 through 28, 1987. At the NIH, the Consensus Development Conference brings together investigators in the biomedical sciences, clinical investigators, practicing physicians, and consumer and special interest groups to make a scientific assessment of technologies, including drugs, devices, and procedures, and to seek agreement on their safety and effectiveness

  1. Investigations of functional and structural changes in migraine with aura by magnetic resonance imaging

    DEFF Research Database (Denmark)

    Hougaard, Anders

    2015-01-01

    technology to study these features of migraine with aura (MA) is functional magnetic resonance imaging (fMRI), which has the potential not only to detect, but also to localize hypersensitive cortex. The main objective of this thesis was to investigate the cortical responsivity of patients with MA during.......e. ≥= 90% of auras occurring in the same visual hemifield (study II). To circumvent bias relating to differences between right and left hemispheres (e.g. caused by physiological left/right bias, asymmetry of the visual stimulation or magnetic field inhomogeneity of the scanner), we included an equal number...

  2. Electromagnetic properties of inner double walled carbon nanotubes investigated by nuclear magnetic resonance

    KAUST Repository

    Bouhrara, M.; Abou-Hamad, E.; Alabedi, G.; Al-Taie, I.; Kim, Y.; Wagberg, T.; Goze-Bac, C.

    2013-01-01

    The nuclear magnetic resonance (NMR) analytical technique was used to investigate the double walled carbon nanotubes (DWNTs) electromagnetic properties of inner walls. The local magnetic and electronic properties of inner nanotubes in DWNTs were analyzed using 25% 13C enriched C 60 by which the effect of dipolar coupling could be minimized. The diamagnetic shielding was determined due to the ring currents on outer nanotubes in DWNTs. The NMR chemical shift anisotropy (CSA) spectra and spin-lattice relaxation studies reveal the metallic properties of the inner nanotubes with a signature of the spin-gap opening below 70 K.

  3. Nuclear magnetic resonance apparatus

    International Nuclear Information System (INIS)

    Lambert, R.

    1991-01-01

    In order to include the effect of a magnetic object in a subject under investigation, Nuclear Magnetic Resonance (NMR) apparatus is operable at more than one radio frequency (RF) frequency. The apparatus allows normal practice as far as obtaining an NMR response or image from a given nuclear species is concerned, but, in addition, interrogates the nuclear spin system at a frequency which is different from the resonance frequency normally used for the given nuclear species, as determined from the applied magnetic field. The magnetic field close to a magnetised or magnetisable object is modified and the given nuclear species gives a response at the different frequency. Thus detection of a signal at the frequency indicates the presence of the chosen nuclei close to the magnetised or magnetisable object. Applications include validation of an object detection or automatic shape inspection system in the presence of magnetic impurities, and the detection of magnetic particles which affect measurement of liquid flow in a pipe. (author)

  4. Investigation of Fat Metabolism during Antiobesity Interventions by Magnetic Resonance Imaging and Spectroscopy

    Directory of Open Access Journals (Sweden)

    Arunima Pola

    2014-01-01

    Full Text Available The focus of current treatments for obesity is to reduce the body weight or visceral fat, which requires longer duration to show effect. In this study, we investigated the short-term changes in fat metabolism in liver, abdomen, and skeletal muscle during antiobesity interventions including Sibutramine treatment and diet restriction in obese rats using magnetic resonance imaging, magnetic resonance spectroscopy, and blood chemistry. Sibutramine is an antiobesity drug that results in weight loss by increasing satiety and energy expenditure. The Sibutramine-treated rats showed reduction of liver fat and intramyocellular lipids on day 3. The triglycerides (TG decreased on day 1 and 3 compared to baseline (day 0. The early response/nonresponse in different fat depots will permit optimization of treatment for better clinical outcome rather than staying with a drug for longer periods.

  5. Optical and magnetic resonance investigations of Zn1-x Mn x O magnetic semiconductors

    International Nuclear Information System (INIS)

    Zhang Huawei; Shi Erwei; Chen Zhizhan; Liu Xuechao; Xiao Bing; Song Lixin

    2006-01-01

    Zn 1- x Mn x O crystallites were synthesized by hydrothermal method. X-ray diffraction, UV-Vis absorption spectroscopy, and electron paramagnetic resonance (EPR) spectra confirm the substitution of Zn site by Mn 2+ ion. The nonmonotonic variation of band gap exhibits that the short-ranged interactions between the d electrons of Mn and the s and p electrons of the host bands are dominated at lower Mn concentration (x). EPR spectra show that Mn 2+ is in exchange interaction at higher x. By using a Curie-Weiss equation on the EPR data, it is found that the dominant magnetic property is antiferromagnetic for higher x, and paramagnetic for lower x

  6. Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium Ion Electrodes

    Science.gov (United States)

    DeSilva, J .H. S. R.; Udinwe, V.; Sideris, P. J.; Smart, M. C.; Krause, F. C.; Hwang, C.; Smith, K. A.; Greenbaum, S. G.

    2012-01-01

    Solid electrolyte interphase (SEI) formation in lithium ion cells prepared with advanced electrolytes is investigated by solid state multinuclear (7Li, 19F, 31P) magnetic resonance (NMR) measurements of electrode materials harvested from cycled cells subjected to an accelerated aging protocol. The electrolyte composition is varied to include the addition of fluorinated carbonates and triphenyl phosphate (TPP, a flame retardant). In addition to species associated with LiPF6 decomposition, cathode NMR spectra are characterized by the presence of compounds originating from the TPP additive. Substantial amounts of LiF are observed in the anodes as well as compounds originating from the fluorinated carbonates.

  7. Pediatric magnetic resonance imaging

    International Nuclear Information System (INIS)

    Cohen, M.D.

    1986-01-01

    This book defines the current clinical potential of magnetic resonance imaging and focuses on direct clinical work with pediatric patients. A section dealing with the physics of magnetic resonance imaging provides an introduction to enable clinicians to utilize the machine and interpret the images. Magnetic resonance imaging is presented as an appropriate imaging modality for pediatric patients utilizing no radiation

  8. Disc pathology after whiplash injury. A prospective magnetic resonance imaging and clinical investigation

    International Nuclear Information System (INIS)

    Pettersson, K.; Hildingsson, C.; Toolanen, G.; Fagerlund, M.; Bjornebrink, J.

    1997-01-01

    Although disc pathology seems to be one contributing factor in the development of chronic symptoms after whiplash injury, it may be unnecessary to examine these patients in the acute phase with magnetic resonance imaging ; correlating initial symptoms and signs to magnetic resonance imaging findings is difficult because of the relatively high proportion of false-positive results. Magnetic resonance imaging is indicated later in the course of treatment in patients with persistent arm pain, neurologic deficits, or clinical signs of nerve root compression to diagnose disc herniations requiring surgery. (authors)

  9. Investigations into the adsorption behaviour of zeolites using nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Hennig, H.J.

    1973-01-01

    The interactions between adsorbed molecules and the walls of the cavities in faujasite have been investigated; even the sodium form of the A type zeolite was included in the investigation. The nuclear magnetic resonance measurements were performed with a varian DP-60 wide line resonance spectrometer. The measuring frequency was generally 16 MHg the modulation frequency 20 Hz. The resonance effect was recorded in the form of the derived absorption signal. It was found that the water molecules form hydrogen bonds to the oxygen ions of the alumozilicate structure, the hydrogen sulphide on the other hand splits off protons which under formation of OH groups bind in the oxygen ions of the alumosilicate structure. The results obtained with sulphur dioxide imply that these molecules bind onto the oxygen ions of the alumosilicate structure via sulphur and thus occupy their free electron pairs. The translation mobility of the absorbed molecules present at room temperature is very much reduced when cooling down to certain temperatures; this solidification temperature of the adsorbate lies below that of the pure liquids. Probably the absorbed molecules are deposited in one or several layers onto the walls of the cavity. Prefered sorption sites for the faujasites are the sodium ions in front of the six-membered rings on the walls fo the large cavities, with NaA, on the other hand, the sodium ions are in the eight-membered rings. (ORU) [de

  10. A deuterium and carbon nuclear magnetic resonance spectroscopic investigation of blood flow and carbohydrate metabolism

    International Nuclear Information System (INIS)

    Bosch, C.S.E.

    1988-01-01

    The purpose of this study is the development and application of nuclear magnetic resonance (NMR) spectroscopic techniques for this study of whole tissue metabolism, tissue perfusion and blood flow. The feasibility of spin imaging deuterium-enriched tissue water is demonstrated in cat brain in vivo and in situ. The potential application of D 2 O administration to deuterium-flow-imaging is considered. NMR investigations of hepatic carbohydrate metabolism were performed in rat liver in vivo and in situ. A coaxial, double-surface-coil, double-resonance probe was developed for carbon detection while decoupling neighboring proton scalar interactions ( 13 C-[ 1 H]) in hepatic tissue within the living animal. Hormonal and substrate regulation of hepatic glucose and glycogen metabolism was investigated by monitoring the metabolic fate of an administered c-dose of [1- 13 C]glucose. Label flux was directed primarily into newly-synthesized 13 C-labeled glycogen. A multiple resonance ( 1 H, 13 C, 31 P) liver perfusion probe was designed for complimentary carbohydrate metabolic studies in rat liver in vitro. A description of the 13 C-[ 1 H]/ 31 P NMR perfusion probe is given. The surgical technique used for liver excision and peripheral life-support apparatus required to maintain hepatic function are also detailed

  11. Advances in magnetic resonance 6

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 6 focuses on the theoretical and practical aspects of applying magnetic resonance methods to various problems in physical chemistry, emphasizing the different aspects of the exegesis of these problems. This book discusses the gas phase magnetic resonance of electronically excited molecules; techniques for observing excited electronic states; NMR studies in liquids at high pressure; and effect of pressure on self-diffusion in liquids. The nuclear magnetic resonance investigations of organic free radicals; measurement of proton coupling constants by NMR; an

  12. Disc pathology after whiplash injury. A prospective magnetic resonance imaging and clinical investigation.

    Science.gov (United States)

    Pettersson, K; Hildingsson, C; Toolanen, G; Fagerlund, M; Björnebrink, J

    1997-02-01

    This study was used to evaluate the relationship between magnetic resonance imaging findings and clinical findings after whiplash injury. To identify initial soft-tissue damage after whiplash injury, the development of disc pathology, and the relationship of disc pathology to clinical findings. Although a few studies have reported pathological magnetic resonance imaging findings after whiplash injuries, there is no prospective study published to our knowledge. Thirty-nine patients, 20 women and 19 men with a mean age of 32 years, were treated for whiplash injury. Magnetic resonance imaging and clinical examination were performed in a blinded manner at a mean of 11 days after trauma. The procedure was repeated at a 2-year follow-up visit. Two patients could not be examined with the second magnetic resonance imaging because of claustrophobia and pregnancy, respectively. The authors found 13 patients (33%) with disc herniations with medullary (six cases) or dura (seven cases) impingement over the 2-year follow-up period. At the follow-up examination all patients with medullary impingement had persistent or increased symptoms, and three of 27 patients (11%) with no or slight changes on magnetic resonance imaging had persistent symptoms. No ligament injuries were diagnosed. Although disc pathology seems to be one contributing factor in the development of chronic symptoms after whiplash injury, it may be unnecessary to examine these patients in the acute phase with magnetic resonance imaging; correlating initial symptoms and signs to magnetic resonance imaging findings is difficult because of the relatively high proportion of false-positive results. Magnetic resonance imaging is indicated later in the course of treatment in patients with persistent arm pain, neurologic deficits or clinical signs of nerve root compression to diagnose disc herniations requiring surgery.

  13. Magnetic resonance imaging apparatus

    International Nuclear Information System (INIS)

    Ehnholm, G.J.

    1991-01-01

    This patent describes an electron spin resonance enhanced magnetic resonance (MR) imaging (ESREMRI) apparatus able to generate a primary magnetic field during periods of nuclear spin transition excitation and magnetic resonance signal detection. This allows the generation of ESREMRI images of a subject. A primary magnetic field of a second and higher value generated during periods of nuclear spin transition excitation and magnetic resonance signal detection can be used to generate conventional MR images of a subject. The ESREMRI and native MR images so generated may be combined, (or superimposed). (author)

  14. Low-temperature nuclear magnetic resonance investigation of systems frustrated by competing exchange interactions

    Science.gov (United States)

    Roy, Beas

    This doctoral thesis emphasizes on the study of frustrated systems which form a very interesting class of compounds in physics. The technique used for the investigation of the magnetic properties of the frustrated materials is Nuclear Magnetic Resonance (NMR). NMR is a very novel tool for the microscopic study of the spin systems. NMR enables us to investigate the local magnetic properties of any system exclusively. The NMR experiments on the different systems yield us knowledge of the static as well as the dynamic behavior of the electronic spins. Frustrated systems bear great possibilities of revelation of new physics through the new ground states they exhibit. The vandates AA'VO(PO4)2 [AA' ≡ Zn2 and BaCd] are great prototypes of the J1-J2 model which consists of magnetic ions sitting on the corners of a square lattice. Frustration is caused by the competing nearest-neighbor (NN) and next-nearest neighbor (NNN) exchange interactions. The NMR investigation concludes a columnar antiferromagnetic (AFM) state for both the compounds from the sharp peak of the nuclear spin-lattice relaxation rate (1/T1) and a sudden broadening of the 31P-NMR spectrum. The important conclusion from our study is the establishment of the first H-P-T phase diagram of BaCdVO(PO4)2. Application of high pressure reduces the saturation field (HS) in BaCdVO(PO4)2 and decreases the ratio J2/J1, pushing the system more towards a questionable boundary (a disordered ground state) between the columnar AFM and a ferromagnetic ground state. A pressure up to 2.4 GPa will completely suppress HS. The Fe ions in the `122' iron-arsenide superconductors also sit on a square lattice thus closely resembling the J1-J2 model. The 75As-NMR and Nuclear Quadrupole Resonance (NQR) experiments are conducted in the compound CaFe2As2 prepared by two different heat treatment methods (`as-grown' and `annealed'). Interestingly the two samples show two different ground states. While the ground state of the `as

  15. Nuclear magnetic resonance investigation of erythrocyte membranes in chronic myeloproliferative disorders.

    Science.gov (United States)

    Morariu, V V; Petrov, L

    1986-07-01

    The temperature dependence of the apparent water diffusional exchange through erythrocyte membranes in cases of policitemia vera, chronic granulocytic leukemia and primary myelofibrosis was measured by using a nuclear magnetic resonance method in the presence of Mn2+. The thermal transition shifted to lower temperatures in all cases, regardless of the stage of the disease, suggesting a structural alteration of the membrane. The shift of transition indirectly suggests a lower penetration of the erythrocytes by Mn2+. The water exchange time at 37 degrees C also increased, mainly in the blast crisis; it seems to have a prognostic value of some clinical interest. No simple correlation of the water exchange and the following clinical investigations was observed: the white count, the percentage of promyelocites and myeloblasts, the sedimentation rate of blood, the osmotic fragility of erythrocytes, the total concentration of proteins, albumin and immunoglobulins, respectively, in plasma.

  16. Investigation of Factors Affecting Body Temperature Changes During Routine Clinical Head Magnetic Resonance Imaging

    Science.gov (United States)

    Kim, Myeong Seong

    2016-01-01

    Background Pulsed radiofrequency (RF) magnetic fields, required to produce magnetic resonance imaging (MRI) signals from tissue during the MRI procedure have been shown to heat tissues. Objectives To investigate the relationship between body temperature rise and the RF power deposited during routine clinical MRI procedures, and to determine the correlation between this effect and the body’s physiological response. Patients and Methods We investigated 69 patients from the Korean national cancer center to identify the main factors that contribute to an increase in body temperature (external factors and the body’s response) during a clinical brain MRI. A routine protocol sequence of MRI scans (1.5 T and 3.0 T) was performed. The patient’s tympanic temperature was recorded before and immediately after the MRI procedure and compared with changes in variables related to the body’s physiological response to heat. Results Our investigation of the physiological response to RF heating indicated a link between increasing age and body temperature. A higher increase in body temperature was observed in older patients after a 3.0-T MRI (r = 0.07, P = 0.29 for 1.5-T MRI; r = 0.45, P = 0.002 for 3.0-T MRI). The relationship between age and body heat was related to the heart rate (HR) and changes in HR during the MRI procedure; a higher RF power combined with a reduction in HR resulted in an increase in body temperature. Conclusion A higher magnetic field strength and a decrease in the HR resulted in an increase in body temperature during the MRI procedure. PMID:27895872

  17. Enhanced magnetic resonance pulmonary perfusion imaging in diagnosing pulmonary embolism: preliminary investigation

    International Nuclear Information System (INIS)

    Huang Xiaoyong; Du Jing; Zhang Zhaoqi; Guo Xi; Yan Zixu; Jiang Hong; Wang Wei

    2005-01-01

    Objective: This study was designed to investigate the sensitivity and specificity of magnetic resonance pulmonary perfusion imaging (MRPP) in diagnosing pulmonary embolism (PE) compared with enhanced magnetic resonance pulmonary angiography (MRPA) and pulmonary radionuclide perfusion imaging. Methods: Fourteen patients were definitely diagnosed as PE, whose ages were from 19 to 71 years old and mean 45.5 ± 19.8 years old. All patients under went MRPA and MRPP and 3 patients were examined again after thrombolytic treatment. Five patients underwent pulmonary radionuclide perfusion imaging. Setting ROI in top, middle, bottom of lung area and abnormal area respectively, we detected signal intensity and time-signal curve to obtain the transformation rate of signal (TROS) during perfusion peak value. Results: In 14 pulmonary embolism patients, MRPA found 62 branches of pulmonary artery obstruction. Fifty-five abnormal pulmonary perfusion zones were found by MRPP, and the above results were very alike. The coincidence was 88.71%. In 14 cases, MRPP could show 25 subsegments lesion below segments. In 5 patients who had both results Of MRPP and ECT at the same time. MRPP shows 33 perfusion defect zones and 37 segments were found by ECT, the sensitivity was 89.19%. After thrombolytic treatment, both the status of the affected pulmonary artery improved markedly and perfusion defect zones reduced obviously in 3 cases by MRPP and MRPA. TROS in normal perfusion zones perfusion defect zones and low perfusion zones had significant difference (t=22.882, P<0.01). Conclusion: Contrast enhanced MR pulmonary perfusion can show both perfusion defect zones and low perfusion zones in pulmonary embolism. Time-signal curve can show the period of maximum no perfusion zones in pulmonary artery embolism zones. And the amplitude of fluctuation is small with miminum TROS. MRPP has significant values especially in showing pulmonary artery embolism in segments and subsegments. Using both MRPP and

  18. Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

    Energy Technology Data Exchange (ETDEWEB)

    Pankin, Alexei Y.; Kritz, Arnold H.

    2011-07-19

    Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

  19. Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

    International Nuclear Information System (INIS)

    Pankin, Alexei Y.; Kritz, Arnold H.

    2011-01-01

    Topics covered are: anomalous transport and E f- B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies

  20. MRI and P-31 Magnetic Resonance Spectroscopy Hardware for Axillary Lymph Node Investigation at 7T

    NARCIS (Netherlands)

    Rivera, Debra S.; Wijnen, Jannie P.; van der Kemp, Wybe J. M.; Raaijmakers, Alexander J.; Luijten, Peter R.; Klomp, DWJ

    PurposeNeoadjuvant treatment response in lymph nodes predicts patient outcome, but existing methods do not track response during therapy accurately. In this study, specialized hardware was used to adapt high-field (7T) P-31 magnetic resonance spectroscopy (MRS), which has been shown to track

  1. Ferromagnetic nuclear resonance investigation of the surface magnetization in iron sheets

    International Nuclear Information System (INIS)

    Varga, L.; Tompa, K.

    1977-09-01

    The role of the domain structure and domain properties in ferromagnetic nuclear resonance (FNR) experiments is reconsidered. Using the FNR signal intensity as a measure of surface domain wall volume, it is found that the behaviour of the surface magnetization differs from that of the bulk magnetization of iron sheets. Namely, a critical field below which the FNR signal remains unchanqed is observed in the surface magnetization. This lag of surface domain wall annihilation is sensitive to the given surface conditions and in particular to the rolling deformation. Considering the small skin depth, FNR as a surface testing method is discussed. (D.P.)

  2. Cardiac magnetic resonance imaging

    African Journals Online (AJOL)

    2011-03-06

    Mar 6, 2011 ... Cardiac magnetic resonance imaging. Cardiovascular magnetic resonance imaging is becoming a routine diagnostic technique. BRUCE s sPOTTiswOOdE, PhD. MRC/UCT Medical Imaging Research Unit, University of Cape Town, and Division of Radiology, Stellenbosch University. Bruce Spottiswoode ...

  3. Magnetic Resonance Force Microscopy System

    Data.gov (United States)

    Federal Laboratory Consortium — The Magnetic Resonance Force Microscopy (MRFM) system, developed by ARL, is the world's most sensitive nuclear magnetic resonance (NMR) spectroscopic analysis tool,...

  4. Assessment of T2-Weighted Coronal Magnetic Resonance Images in the Investigation of Pituitary Lesions

    International Nuclear Information System (INIS)

    Yuksekkaya, Ruken; Aggunlu, Levent; Oner, Yusuf; Celik, Halil; Akpek, Sergin; Celikyay, Fatih

    2014-01-01

    Magnetic resonance imaging is the most important diagnostic method in the investigation of the pituitary lesions. Our aim is to determine whether T2-weighted coronal images may be helpful in the evaluation of the pituitary gland with suspected pituitary adenomas. One hundred and sixty-seven patients were examined prospectively with T2-weighted coronal and T1-weighted coronal images enhanced with intravenous contrast material. The images were evaluated for the presence, the size, the location, and the ancillary signs including sellar floor erosion or ballooning, infindibulary deviation, convexity of the superior border of the gland, diffuse enlargement of the gland, and the invasion of the cavenous sinuses on both images. In forty-six (28%) patients lesions were revealed on both sequences. In twenty-one (12%) patients the lesions that were revealed on the T1-weighted images were not detected on the T2-weighted images. Positive predictive value, negative predictive value, sensitivity, specificity, and diagnostic accuracy rates of T2-weighted coronal images on the detection of the presence of lesions were 100%, 17.4%, 68.7%, 100%, and 87.4%, respectively. Both T2-weighted coronal and T1-weighted coronal images enhanced with intravenous gadolinium-based contrast material are important in the diagnosis of pituitary adenomas. T2-weighted coronal images could be used as a screening tool for the primary evaluation of the pituitary gland

  5. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR

    Directory of Open Access Journals (Sweden)

    Francesco Tres

    2015-09-01

    Full Text Available We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide. A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

  6. Properties of Cs-intercalated single wall carbon nanotubes investigated by 133Cs Nuclear Magnetic resonance

    KAUST Repository

    Schmid, Marc R.

    2012-11-01

    In the present study, we investigated Cs-intercalated single wall carbon nanotubes (SWCNTs) using 133Cs Nuclear Magnetic resonance. We show that there are two types of Cs cations depending on the insertion level. Indeed, at low concentrations, Static spectra analysis shows that the Cs (α)+ species are fully ionized, i.e. α equal ca.1, while at higher concentrations a second paramagnetically shifted line appears, indicating the formation of Cs (β)+ ions with β < α ∼ +1. At low concentrations and low temperatures the Cs (α)+ ions exhibit a weak hyperfine coupling to the SWCNT conduction electrons, whereas, at higher temperatures, a thermally activated slow-motion diffusion process of the Cs (α)+ ions occurs along the interstitial channels present within the carbon nanotube bundles. At high concentrations, the Cs (β)+ ions seem to occupy well defined positions relative to the carbon lattice. As a matter of fact, the Korringa relaxation behavior suggests a strong hyperfine coupling between Cs nuclei and conduction electrons in the carbon nanotubes and a partial charge transfer, which suggest a plausible Cs(6s)-C(2p) hybridization. © 2012 Elsevier Ltd. All rights reserved.

  7. Nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Ethier, R.; Melanson, D.; Peters, T.M.

    1983-01-01

    Ten years following computerized tomography, a new technique called nuclear magnetic resonance revolutionizes the field of diagnostic imaging. A major advantage of nuclear magnetic resonance is that the danger of radiation is non-existent as compared to computerized tomography. When parts of the human body are subject to radio-frequencies while in a fixed magnetic field, its most detailed structures are revealed. The quality of images, the applications, as well as the indications are forever increasing. Images obtained at the level of the brain and spinal cord through nuclear magnetic resonance supercede those obtained through computerized tomography. Hence, it is most likely that myelography, along with pneumoencephalography will be eliminated as a diagnostic means. It is without a doubt that nuclear magnetic resonance is tomorrow's computerized tomography [fr

  8. Solid state nuclear magnetic resonance: investigating the spins of nuclear related materials

    International Nuclear Information System (INIS)

    Charpentier, Th.

    2007-10-01

    The author reviews his successive research works: his research thesis work on the Multiple Quantum Magic Angle Spinning (MQMAS) which is a quadric-polar nucleus multi-quanta correlation spectroscopy method, the modelling of NMR spectra of disordered materials, the application to materials of interest for the nuclear industry (notably the glasses used for nuclear waste containment). He presents the various research projects in which he is involved: storing glasses, nuclear magnetic resonance in paramagnetism, solid hydrogen storing matrices, methodological and instrument developments in high magnetic field and high resolution solid NMR, long range distance measurement by solid state Tritium NMR (observing the structure and dynamics of biological complex systems at work)

  9. Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer: a meta-analysis

    International Nuclear Information System (INIS)

    Purkayastha, S.; Tekkis, P.P.; Athanasiou, T.; Aziz, O.; Negus, R.; Gedroyc, W.; Darzi, A.W.

    2005-01-01

    AIMS: Magnetic resonance colonography (MRC) is emerging as a potential complementary investigation for the diagnosis of colorectal cancer (CRC) and also for benign pathology such as diverticular disease. A meta-analysis reporting the use of MRC is yet to be performed. The aim of this study was to evaluate the diagnostic accuracy of MRC compared with the gold-standard investigation, conventional colonoscopy (CC). METHODS: A literature search was carried out to identify studies containing comparative data between MRC findings and CC findings. Quantitative meta-analysis for diagnostic tests was performed, which included the calculation of independent sensitivities, specificities, diagnostic odds ratios, the construction of summary receiver operating characteristic (SROC) curves, pooled analysis and sensitivity analysis. The study heterogeneity was evaluated by the Q-test using a random-effect model to accommodate the cluster of outcomes between individual studies. RESULTS: In all, 8 comparative studies were identified, involving 563 patients. The calculated pooled sensitivity for all lesions was 75% (95% CI: 47% to 91%), the specificity was 96% (95% CI: 86% to 98%) and the area under the ROC curve was 90% (weighted). On sensitivity analysis, MRC had a better diagnostic accuracy for CRC than for polyps, with a sensitivity of 91% (95% CI: 97% to 91%), a specificity of 98% (95% CI: 66% to 99%) and an area under the ROC curve of 92%. There was no significant heterogeneity between the studies with regard to the diagnostic accuracy of MRC for CRC. CONCLUSION: This meta-analysis suggests that MRC is an imaging technique with high discrimination for cases presenting with colorectal cancer. The exact diagnostic role of MRC needs to be clarified (e.g. suitable for an elderly person with suspected CRC). Further evaluation is necessary to refine its applicability and diagnostic accuracy in comparison with other imaging methods such as computed tomography colonography

  10. Magnetic Resonance (MR) Defecography

    Science.gov (United States)

    ... to a CD or uploaded to a digital cloud server. Magnetic resonance (MR) defecography is a special ... with you. top of page What are the benefits vs. risks? Benefits MR defecography helps assess pelvic ...

  11. Magnetic resonance angiography (MRA)

    International Nuclear Information System (INIS)

    Arlart, I.P.; Guhl, L.

    1992-01-01

    An account is given in this paper of the physical and technical principles underlying the 'time-of-flight' technique for imaging of vessels by magnetic resonance tomography. Major indications for the new procedure of magnetic resonance angiography at present are intracerebral and extracerebral vessels, with digital subtraction angiography quite often being required to cope with minor alterations (small aneurysms, small occlusions). Magnetic resonance angiography and digital subtraction angiography are compared to each other for advantages and disadvantages. Basically, replacement of radiological angiography by magnetic resonance angiography appears to be possible only within limits, since X-ray diagnostics primarily provides morphological information about vessels, whereas flow dynamics is visualized by the 'time-of-flight' technique. (orig.) [de

  12. Magnetic Resonance Cholangiopancreatography (MRCP)

    Science.gov (United States)

    ... radio waves and a computer to evaluate the liver, gallbladder, bile ducts, pancreas and pancreatic duct for disease. It is ... of the hepatobiliary and pancreatic systems, including the liver, gallbladder, bile ducts, pancreas and pancreatic duct . Magnetic resonance imaging (MRI) ...

  13. Magnetic Resonance Sensors

    Directory of Open Access Journals (Sweden)

    Robert H. Morris

    2014-11-01

    Full Text Available Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application. With beginnings in borehole logging for the petro-chemical industry Magnetic Resonance sensors have been applied to fields as varied as online process monitoring for food manufacture and medical point of care diagnostics. This great diversity is seeing exciting developments in magnetic resonance sensing technology published in application specific journals where they are often not seen by the wider sensor community. It is clear that there is enormous interest in magnetic resonance sensors which represents a significant growth area. The aim of this special edition of Sensors was to address the wide distribution of relevant articles by providing a forum to disseminate cutting edge research in this field in a single open source publication.[...

  14. Magnetic resonance angiography

    Science.gov (United States)

    ... Saunders; 2015:chap 17. Litt H, Carpenter JP. Magnetic resonance imaging. In: Cronenwett JL, Johnston KW, eds. Rutherford's Vascular Surgery . 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap ...

  15. Magnetic resonance imaging

    International Nuclear Information System (INIS)

    Robertson, Angus

    1990-01-01

    An assessment is made of the clinical benefits of expensive diagnostic technology, such as the magnetic resonance imaging. It is concluded that to most radiologists, magnetic resonance imaging has a definite place in the diagnostic scenario, especially for demonstrating central nervous system lesions in multiple sclerosis. While it is recognized that medical and financial resources are limited, it is emphasised that the cost to society must be balanced against the patient benefit. 17 refs

  16. Nuclear magnetic resonance gyroscope

    International Nuclear Information System (INIS)

    Grover, B.C.

    1984-01-01

    A nuclear magnetic resonance gyro using two nuclear magnetic resonance gases, preferably xenon 129 and xenon 131, together with two alkaline metal vapors, preferably rubidium, potassium or cesium, one of the two alkaline metal vapors being pumped by light which has the wavelength of that alkaline metal vapor, and the other alkaline vapor being illuminated by light which has the wavelength of that other alkaline vapor

  17. Nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    In a method of imaging a body in which nuclear magnetic resonance is excited in a region including part of the body, and the free induction decay signal is measured, a known quantity of a material of known nuclear magnetic resonance properties, for example a bag of water, is included in the region so as to enhance the measured free induction decay signal. This then reduces the generation of noise during subsequent processing of the signal. (author)

  18. Laser magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Ferrari, C.A.

    1985-01-01

    The technique of laser resonance magnetic resonance allows one to study the high-resolution spectroscopy of transient paramagnetic species, viz, atoms, radicals, and molecular ions. This article is a brief exposition of the method, describing the principles, instrumentation and applicability of the IR and FIR-LMR and shows results of HF + . (Author) [pt

  19. Nuclear Magnetic Resonance Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 9; Issue 1. Nuclear Magnetic Resonance Spectroscopy. Susanta Das. General Article Volume 9 Issue 1 January 2004 pp 34-49. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/009/01/0034-0049. Keywords.

  20. Magnetic resonance sialography for investigating major salivary gland duct system after intensity-modulated radiotherapy of nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Ou Dan; He Xiayun; Zhang Yunyan

    2013-01-01

    We investigated the value of magnetic resonance sialography for evaluating xerostomia induced by intensity-modulated radiotherapy for nasopharyngeal carcinoma. Fourteen patients with nasopharyngeal carcinoma were treated with intensity-modulated radiotherapy. Salivary function was assessed by magnetic resonance sialography and subjective evaluation criteria pre-treatment, 1 week and 1 year post-radiotherapy. A magnetic resonance sialography categorical scoring system was used to compare the visibility of salivary ducts. The average mean dose was 38.93 Gy to the parotid glands and 59.34 Gy to the submandibular glands. Before radiotherapy, the visibility scores of both the parotid and submandibular ducts increased after secretion stimulation. The scores decreased and the response to stimulation was attenuated 1 week post-radiotherapy. For most of the parotid ducts, the visibility score improved at 1 year post-radiotherapy both at rest and under stimulation, but not for the submandibular ducts. With a median follow-up of 12.3 months, 8/12 patients had grade 1 xerostomia and 4/12 had grade 2 xerostomia. Magnetic resonance sialography allows non-invasive evaluation of radiation-induced ductal changes in the major salivary glands and enables reliable prediction of radiation-induced xerostomia. (author)

  1. Design and investigations of the superconducting magnet system for the multipurpose superconducting electron cyclotron resonance ion source.

    Science.gov (United States)

    Tinschert, K; Lang, R; Mäder, J; Rossbach, J; Spädtke, P; Komorowski, P; Meyer-Reumers, M; Krischel, D; Fischer, B; Ciavola, G; Gammino, S; Celona, L

    2012-02-01

    The production of intense beams of heavy ions with electron cyclotron resonance ion sources (ECRIS) is an important request at many accelerators. According to the ECR condition and considering semi-empirical scaling laws, it is essential to increase the microwave frequency together with the magnetic flux density of the ECRIS magnet system. A useful frequency of 28 GHz, therefore, requires magnetic flux densities above 2.2 T implying the use of superconducting magnets. A cooperation of European institutions initiated a project to build a multipurpose superconducting ECRIS (MS-ECRIS) in order to achieve an increase of the performances in the order of a factor of ten. After a first design of the superconducting magnet system for the MS-ECRIS, the respective cold testing of the built magnet system reveals a lack of mechanical performance due to the strong interaction of the magnetic field of the three solenoids with the sextupole field and the magnetization of the magnetic iron collar. Comprehensive structural analysis, magnetic field calculations, and calculations of the force pattern confirm thereafter these strong interactions, especially of the iron collar with the solenoidal fields. The investigations on the structural analysis as well as suggestions for a possible mechanical design solution are given.

  2. Investigating spin-transfer torques induced by thermal gradients in magnetic tunnel junctions by using micro-cavity ferromagnetic resonance

    Science.gov (United States)

    Cansever, H.; Narkowicz, R.; Lenz, K.; Fowley, C.; Ramasubramanian, L.; Yildirim, O.; Niesen, A.; Huebner, T.; Reiss, G.; Lindner, J.; Fassbender, J.; Deac, A. M.

    2018-06-01

    Similar to electrical currents flowing through magnetic multilayers, thermal gradients applied across the barrier of a magnetic tunnel junction may induce pure spin-currents and generate ‘thermal’ spin-transfer torques large enough to induce magnetization dynamics in the free layer. In this study, we describe a novel experimental approach to observe spin-transfer torques induced by thermal gradients in magnetic multilayers by studying their ferromagnetic resonance response in microwave cavities. Utilizing this approach allows for measuring the magnetization dynamics on micron/nano-sized samples in open-circuit conditions, i.e. without the need of electrical contacts. We performed first experiments on magnetic tunnel junctions patterned into 6  ×  9 µm2 ellipses from Co2FeAl/MgO/CoFeB stacks. We conducted microresonator ferromagnetic resonance (FMR) under focused laser illumination to induce thermal gradients in the layer stack and compared them to measurements in which the sample was globally heated from the backside of the substrate. Moreover, we carried out broadband FMR measurements under global heating conditions on the same extended films the microstructures were later on prepared from. The results clearly demonstrate the effect of thermal spin-torque on the FMR response and thus show that the microresonator approach is well suited to investigate thermal spin-transfer-driven processes for small temperatures gradients, far below the gradients required for magnetic switching.

  3. Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse.

    Science.gov (United States)

    Tsuchida, Jefferson Esquina; Rezende, Camila Alves; de Oliveira-Silva, Rodrigo; Lima, Marisa Aparecida; d'Eurydice, Marcel Nogueira; Polikarpov, Igor; Bonagamba, Tito José

    2014-01-01

    Enzymatic hydrolysis is a crucial step of biomass conversion into biofuels and different pretreatments have been proposed to improve the process efficiency. Amongst the various factors affecting hydrolysis yields of biomass samples, porosity and water accessibility stand out due to their intimate relation with enzymes accessibility to the cellulose and hemicellulose fractions of the biomass. In this work, sugarcane bagasse was subjected to acid and alkali pretreatments. The changes in the total surface area, hydrophilicity, porosity and water accessibility of cellulose were investigated by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). Changes in chemical and physical properties of the samples, caused by the partial removal of hemicellulose and lignin, led to the increase in porosity of the cell walls and unwinding of the cellulose bundles, as observed by SEM. (1)H NMR relaxation data revealed the existence of water molecules occupying the cores of wide and narrow vessels as well as the cell wall internal structure. Upon drying, the water molecules associated with the structure of the cell wall did not undergo significant dynamical and partial moisture changes, while those located in the cores of wide and narrow vessels kept continuously evaporating until reaching approximately 20% of relative humidity. This indicates that water is first removed from the cores of lumens and, in the dry sample, the only remaining water molecules are those bound to the cell walls. The stronger interaction of water with pretreated bagasse is consistent with better enzymes accessibility to cellulose and higher efficiency of the enzymatic hydrolysis. We were able to identify that sugarcane bagasse modification under acid and basic pretreatments change the water accessibility to different sites of the sample, associated with both bagasse structure (lumens and cell walls) and hydrophilicity (lignin removal). Furthermore, we show that the substrates with increased

  4. Nuclear magnetic resonance scattering

    International Nuclear Information System (INIS)

    Young, I.R.

    1985-01-01

    A nuclear magnetic resonance apparatus is described including a magnet system which is capable of providing a steady magnetic field along an axis, and is constructed so as to define a plurality of regions along the axis in each of which the field is substantially homogeneous so that in each region an imaging operation may be separately carried out. Iron shields increase the field homogeneity. In use, each patient lies on a wheeled trolley which is provided with magnetic field gradient coils and an RF coil system, some of the coils being movable to facilitate positioning of the patient, and there are terminals for connection to a common computing and control facility. (author)

  5. Investigation of local fields in different barium ferrite sublattices by means of nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Utrecht, R.; Hankiewicz, J.

    1995-01-01

    The local fields on 57 Fe nuclei in ferrite (BaFe 12 O 19 ) polycrystals have been investigated by means of spin echo amplitudes measurements at 4.2 and 77 K. The magnetic moment orientation and local field intensity have been determined for five different ferrite sublattices

  6. Magnetic resonance annual, 1988

    International Nuclear Information System (INIS)

    Kressel, H.Y.

    1987-01-01

    This book features reviews of high-resolution MRI of the knee, MRI of the normal and ischmeic hip, MRI of the heart, and temporomandibular joint imaging, as well as thorough discussion on artifacts in magnetic resonance imaging. Contributors consider the clinical applications of gadolinium-DTPA in magnetic resonance imaging and the clinical use of partial saturation and saturation recovery sequences. Timely reports assess the current status of rapid MRI and describe a new rapid gated cine MRI technique. Also included is an analysis of cerebrospinal fluid flow effects during MRI of the central nervous system

  7. Advances in magnetic resonance 10

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 10, presents a variety of contributions to the theory and practice of magnetic resonance. The book contains three chapters that examine superoperators in magnetic resonance; ultrasonically modulated paramagnetic resonance; and the utility of electron paramagnetic resonance (EPR) and electron-nuclear double-resonance (ENDOR) techniques for studying low-frequency modes of atomic fluctuations and their significance for understanding the mechanism of structural phase transitions in solids.

  8. Measurement of renal blood flow by phase-contrast magnetic resonance imaging during septic acute kidney injury: a pilot investigation.

    Science.gov (United States)

    Prowle, John R; Molan, Maurice P; Hornsey, Emma; Bellomo, Rinaldo

    2012-06-01

    established septic acute kidney injury. Cine phase-contrast magnetic resonance imaging may be a valuable tool to further investigate renal blood flow and the effects of therapies on renal blood flow in critical illness.

  9. Erythrocytes in muscular dystrophy. Investigation with 31P nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Sarpel, G.; Lubansky, H.J.; Danon, M.J.; Omachi, A.

    1981-01-01

    Phosphorus 31 nuclear magnetic resonance ( 31 P NMR) signals were recorded from intact human erythrocytes for 16 hours. Total phosphate concentration, which was estimated as the sum of the individual 31 P signals, was 25% lower in erythrocytes from men with myotonic dystrophy than in control erythrocytes. The inorganic-phosphate fraction contained the highest average phosphate concentration over the 16-hour period, and made the major contribution to the difference in total phosphate between the two groups. This result was not observed in erythrocytes from either women with myotonic dystrophy or patients with Duchenne's dystrophy and may be due to a change in cell membrane permeability to inorganic phosphate, which leads to lower steady-state concentrations of the intracellular phosphates

  10. Erythrocytes in muscular dystrophy. Investigation with 31P nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Sarpel, G.; Lubansky, H.J.; Danon, M.J.; Omachi, A.

    1981-01-01

    Phosphorus 31 nuclear magnetic resonance (31P NMR) signals were recorded from intact human erythrocytes for 16 hours. Total phosphate concentration, which was estimated as the sum of the individual 31P signals, was 25% lower in erythrocytes from men with myotonic dystrophy than in control erythrocytes. The inorganic-phosphate fraction contained the highest average phosphate concentration over the 16-hour period, and made the major contribution to the difference in total phosphate between the two groups. This result was not observed in erythrocytes from either women with myotonic dystrophy or patients with Duchenne's dystrophy and may be due to a change in cell membrane permeability to inorganic phosphate, which lead to lower steady-state concentrations of the intracellular phosphates

  11. Phosphor investigation in the production of Syrian phosphoric acid using Nuclear Magnetic Resonance

    International Nuclear Information System (INIS)

    Al-Hassanieh, O.; Al-Hameish, M.

    2009-06-01

    Nuclear magnetic resonance spectroscopy (NMR) was applied in this work to the industrial process of extraction of uranium from phosphoric acid and to the process of the purification of the phosphoric acid for food proposes. The structural changes of used extraction materials and the organic content of the final product was studied. 13 C , 1 H and 32 P-spectra of all material during the process were recorded. The spectra of the three used extraction materials Bis(2-ethylhexyl Phosphoric Acid)) DEHPA, TriOctyl Phosphine Oxide (TOPO) (C 8 H 1 7) 3 P=O and TriButyl Phosphate (TBP) (C 4 H 9 O) 3 P=O show a partial degradation during the process. The final product ( Phosphoric acid for Food proposes) doesn't contain any organic solvents or extraction material. (author)

  12. Investigation of magnetic resonance imaging texture analysis as an aid tool for characterization of refractory epilepsies

    Directory of Open Access Journals (Sweden)

    Mauricio Martins Baldissin

    2013-12-01

    Full Text Available Refractory epilepsies are syndromes for which therapies that employ two or more antiepileptic drugs, separately or in association, do not result in control of crisis. Patients may present focal cortical dysplasia or diffuse dysplasia and/or hippocampal atrophic alterations that may not be detectable by a simple visual analysis in magnetic resonance imaging. The aim of this study was to evaluate MRI texture in regions of interest located in the hippocampi, limbic association cortex and prefrontal cortex of 20 patients with refractory epilepsy and to compare them with the same areas in 20 healthy individuals, in order to find out if the texture parameters could be related to the presence of the disease. Of the 11 texture parameters calculated, three indicated the existence of statistically significant differences between the studied groups. Such findings suggest the possibility of this technique contributing to studies of refractory epilepsies.

  13. Investigation on Mechanisms of Polymer Enhanced Oil Recovery by Nuclear Magnetic Resonance and Microscopic Theoretical Analysis

    International Nuclear Information System (INIS)

    Ji-Cheng, Zhang; Kao-Ping, Song; Er-Long, Yang; Li, Liu

    2008-01-01

    Polymer flooding is an efficient technique to enhance oil recovery over water flooding. There are lots of discussions regarding the mechanisms for polymer flooding enhancing oil recovery. The main focus is whether polymer flooding can increase sweep efficiency alone, or can increase both of sweep efficiency and displacement efficiency. We present a study on this problem. Oil displacement experiments on 4 natural cores show that polymer flooding can increase oil recovery efficiency by more than 12% over water. Moreover, photos are taken by the nuclear magnetic resonance (NMR) method both after water flooding and after polymer flooding, which show remaining oil saturation distribution at the middle cross section and the central longitudinal section. Analyses of these photos demonstrate that polymer flooding can increase both sweep efficiency and displacement efficiency. (fundamental areas of phenomenology (including applications))

  14. Time-Domain Nuclear Magnetic Resonance Investigation of Water Dynamics in Different Ginger Cultivars.

    Science.gov (United States)

    Huang, Chongyang; Zhou, Qi; Gao, Shan; Bao, Qingjia; Chen, Fang; Liu, Chaoyang

    2016-01-20

    Different ginger cultivars may contain different nutritional and medicinal values. In this study, a time-domain nuclear magnetic resonance method was employed to study water dynamics in different ginger cultivars. Significant differences in transverse relaxation time T2 values assigned to the distribution of water in different parts of the plant were observed between Henan ginger and four other ginger cultivars. Ion concentration and metabolic analysis showed similar differences in Mn ion concentrations and organic solutes among the different ginger cultivars, respectively. On the basis of Pearson's correlation analysis, many organic solutes and 6-gingerol, the main active substance of ginger, exhibited significant correlations with water distribution as determined by NMR T2 relaxation, suggesting that the organic solute differences may impact water distribution. Our work demonstrates that low-field NMR relaxometry provides useful information about water dynamics in different ginger cultivars as affected by the presence of different organic solutes.

  15. Magnetic defects in chemically converted graphene nanoribbons: electron spin resonance investigation

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao Singamaneni

    2014-04-01

    Full Text Available Electronic spin transport properties of graphene nanoribbons (GNRs are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element spin-sensitive techniques such as electron spin resonance (ESR spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW, pulse and hyperfine sublevel correlation (HYSCORE ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs, which were subsequently chemically converted (CCGNRs with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH3 adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns and fast (39 ns components. HYSCORE ESR data demonstrate the explicit presence of protons and 13C atoms. With the provided identification of intrinsic point magnetic defects such as proton and 13C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic-based transport properties of CCGNRs.

  16. Magnetic defects in chemically converted graphene nanoribbons: electron spin resonance investigation

    Energy Technology Data Exchange (ETDEWEB)

    Singamaneni, Srinivasa Rao, E-mail: ssingam@ncsu.edu [INPAC – Institute for Nanoscale Physics and Chemistry, Semiconductor Physics Laboratory, K.U. Leuven, Celestijnenlaan 200D, B–3001 Leuven (Belgium); Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States); Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Stesmans, Andre [INPAC – Institute for Nanoscale Physics and Chemistry, Semiconductor Physics Laboratory, K.U. Leuven, Celestijnenlaan 200D, B–3001 Leuven (Belgium); Tol, Johan van [National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310 (United States); Kosynkin, D. V. [Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Tour, James M. [Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Department of Mechanical Engineering and Materials Science, Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005, USA. (United States)

    2014-04-15

    Electronic spin transport properties of graphene nanoribbons (GNRs) are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element) spin-sensitive techniques such as electron spin resonance (ESR) spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW), pulse and hyperfine sublevel correlation (HYSCORE) ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs), which were subsequently chemically converted (CCGNRs) with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH{sub 3} adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns) and fast (39 ns) components. HYSCORE ESR data demonstrate the explicit presence of protons and {sup 13}C atoms. With the provided identification of intrinsic point magnetic defects such as proton and {sup 13}C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic)-based transport properties of CCGNRs.

  17. Imaging by magnetic resonance

    International Nuclear Information System (INIS)

    Duroure, J.F.; Serpolay, H.; Vallens, D.

    1995-01-01

    Here are described the advanced technology for nuclear magnetic resonance imaging: reduction of acquisition times, and rebuilding times, images quality improvement. The tendency is to open the machines at low and middle field, on a market being at 10% of NMR I sales, with economical, scientifical and ergonomic reasons broadly developed by constructors

  18. Magnetic resonance fingerprinting.

    Science.gov (United States)

    Ma, Dan; Gulani, Vikas; Seiberlich, Nicole; Liu, Kecheng; Sunshine, Jeffrey L; Duerk, Jeffrey L; Griswold, Mark A

    2013-03-14

    Magnetic resonance is an exceptionally powerful and versatile measurement technique. The basic structure of a magnetic resonance experiment has remained largely unchanged for almost 50 years, being mainly restricted to the qualitative probing of only a limited set of the properties that can in principle be accessed by this technique. Here we introduce an approach to data acquisition, post-processing and visualization--which we term 'magnetic resonance fingerprinting' (MRF)--that permits the simultaneous non-invasive quantification of multiple important properties of a material or tissue. MRF thus provides an alternative way to quantitatively detect and analyse complex changes that can represent physical alterations of a substance or early indicators of disease. MRF can also be used to identify the presence of a specific target material or tissue, which will increase the sensitivity, specificity and speed of a magnetic resonance study, and potentially lead to new diagnostic testing methodologies. When paired with an appropriate pattern-recognition algorithm, MRF inherently suppresses measurement errors and can thus improve measurement accuracy.

  19. Functional Magnetic Resonance Imaging

    Science.gov (United States)

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  20. Nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Rueterjans, H.

    1987-01-01

    Contributions by various authors who are working in the field of NMR imaging present the current status and the perspectives of in-vivo nuclear magnetic resonance spectroscopy, explaining not only the scientific and medical aspects, but also technical and physical principles as well as questions concerning practical organisation and training, and points of main interest for further research activities. (orig./TRV) [de

  1. Nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    1983-06-01

    This report summarises the aspects of nuclear magnetic resonance imaging (NMRI) considered by the National Health Technology Advisory Panel and makes recommendations on its introduction in Australia with particular regard to the need for thorough evaluation of its cost effectiveness. Topics covered are: principles of the technique, equipment required, installation, costs, reliability, performance parameters, clinical indications, training and staff requirements, and safety considerations

  2. Development of Selective Excitation Methods in Nuclear Magnetic Resonance: Investigation of Hemoglobin Oxygenation in Erythrocytes Using Proton and Phosphorus -31 Nuclear Magnetic Resonance

    Science.gov (United States)

    Fetler, Bayard Keith

    1993-01-01

    Nuclear magnetic resonance (NMR) offers a potential method for making measurements of the percent oxygenation of hemoglobin (Hb) in living tissue non-invasively. As a demonstration of the feasibility of such measurements, we measured the percent oxygenation of Hb in red blood cells (erythrocytes) using resonances in the proton-NMR (^1H-NMR) spectrum which are characteristic of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb), and are due to the unique magnetic properties of these molecules. To perform these measurements, we developed a new NMR method of selectively exciting signals in a region of interest with uniform phase and amplitude, while suppressing the signal of the water resonance. With this method, we are able to make exact calculations distinguishing between uniform phase excitation produced at large flip-angles using the non-linear properties of the Bloch equations, and uniform phase excitation produced at small flip-angles using asymmetric pulse excitation functions. We measured the percent oxygenation of three characteristic ^1H-NMR resonances of Hb: two from deoxy-Hb, originating from the N_delta H protons of histidine residue F8, which occur at different frequencies for the alpha and beta chains of Hb; and one from oxy-Hb, originating from the gamma_2 -CH_3 protons of valine residue E11. We performed experiments both on fresh erythrocytes and on erythrocytes depleted of 2,3-diphosphoglycerate (2,3-DPG), and found that oxygen is more tightly bound to Hb in the former case. In both fresh and 2,3-DPG-depleted samples, we found that: (i) from the deoxy-Hb marker resonances, there is a small but significant difference in the oxygen saturation between the alpha and beta chains; (ii) the decrease in the areas of the deoxy-Hb marker resonances correlates well with the increase in the percent oxygenation of Hb as measured optically; (iii) the area of the oxy-Hb marker resonance may be up to ~15% less than the optically measured Hb saturation. We are

  3. Evanescent Waves Nuclear Magnetic Resonance

    DEFF Research Database (Denmark)

    Halidi, El Mohamed; Nativel, Eric; Akel, Mohamad

    2016-01-01

    Nuclear Magnetic Resonance spectroscopy and imaging can be classified as inductive techniques working in the near- to far-field regimes. We investigate an alternative capacitive detection with the use of micrometer sized probes positioned at sub wavelength distances of the sample in order...

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... for Brain Tumors Radiation Therapy for Head and Neck Cancer Others : American Stroke Association National Stroke Association ... MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging ( ...

  5. Magnetic Resonance Imaging (MRI) Safety

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) Safety What is MRI and how ... What is MRI and how does it work? Magnetic resonance imaging, or MRI, is a way of obtaining ...

  6. Magnetic Resonance Imaging of Stroke

    NARCIS (Netherlands)

    Bouts, Mark. J. R. J.; Wu, O.; Dijkhuizen, R. M.

    2017-01-01

    Magnetic resonance imaging (MRI) provides a powerful (neuro)imaging modality for the diagnosis and outcome prediction after (acute) stroke. Since MRI allows noninvasive, longitudinal, and three-dimensional assessment of vessel occlusion (with magnetic resonance angiography (MRA)), tissue injury

  7. Optical and magnetic resonance investigations of Zn{sub 1-} {sub x} Mn {sub x} O magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Huawei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Shi Erwei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Chen Zhizhan [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)]. E-mail: zzchen@mail.sic.ac.cn; Liu Xuechao [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Xiao Bing [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Song Lixin [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2006-10-15

    Zn{sub 1-} {sub x} Mn {sub x} O crystallites were synthesized by hydrothermal method. X-ray diffraction, UV-Vis absorption spectroscopy, and electron paramagnetic resonance (EPR) spectra confirm the substitution of Zn site by Mn{sup 2+} ion. The nonmonotonic variation of band gap exhibits that the short-ranged interactions between the d electrons of Mn and the s and p electrons of the host bands are dominated at lower Mn concentration (x). EPR spectra show that Mn{sup 2+} is in exchange interaction at higher x. By using a Curie-Weiss equation on the EPR data, it is found that the dominant magnetic property is antiferromagnetic for higher x, and paramagnetic for lower x.

  8. Magnetic resonance of phase transitions

    CERN Document Server

    Owens, Frank J; Farach, Horacio A

    1979-01-01

    Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

  9. Excange interactions and induced Eu3+ magnetic order in RMnO3 investigated using resonant X-ray diffraction

    International Nuclear Information System (INIS)

    Skaugen, Arvid

    2015-03-01

    The so-called multiferroics, materials that concomitantly exhibit more than one ferroic order, have in recent years attracted much attention owing to their possible applications in high density data storage, high sensitivity ac magnetic field sensors and novel spintronic devices. In particular, multiferroics with strong magnetoelectric coupling are more attractive. Among such multiferroics, an interesting special class is the orthorhombic manganites with perovskite structure. In these compounds, frustration serves to destabilize ordinary ferromagnetic or antiferromagnetic ordering, giving rise to rich phase diagrams due to several competing magnetic interactions. Interactions between strong rare earth magnetic moments and weaker transition metal moments add another level of complexity, as well as interest. The current dissertation presents results obtained investigating the magnetic structure responsible for ferroelectricity in a few selected multiferroic compounds, using x-ray resonant magnetic scattering (XRMS). In particular, single crystals of Eu 1-x Y x MnO 3 have been studied at low temperatures and in high magnetic fields. This series of compounds is similar in structure to the heavily studied RMnO 3 (R=Tb,Gd,Dy), only without rare earth magnetism. The novel technique of full polarization analysis has been used to determine the complicated cycloidal Mn magnetic ordering, and additional components due to the Dzyaloshinskii-Moriya interactions have been identified. In the compound Eu 0.8 Y 0.2 MnO 3 , two coexisting multiferroic phases were observed, and a magnetoelectric coupling between the two was established. Moreover, magnetic order of the formally non-magnetic rare earth ion Eu 3+ was observed in the same compound. It has been concluded to result from a Van Vleck type excitation of the J = 0 ground state due to the symmetry-breaking internal exchange field from the Mn magnetic moments. In addition, this dissertation reports on high field investigations

  10. Children's (Pediatric) Magnetic Resonance Imaging

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) ... limitations of Children’s (Pediatric) MRI? What is Children’s (Pediatric) MRI? Magnetic resonance imaging (MRI) is a noninvasive ...

  11. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) ... limitations of Children’s (Pediatric) MRI? What is Children’s (Pediatric) MRI? Magnetic resonance imaging (MRI) is a noninvasive ...

  12. Magnetic Resonance Imaging (MRI) -- Head

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

  13. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging ( ... the limitations of Children’s (Pediatric) MRI? What is Children’s (Pediatric) MRI? Magnetic resonance imaging (MRI) is a ...

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

  15. Investigations of the human visual system using functional magnetic resonance imaging (FMRI)

    International Nuclear Information System (INIS)

    Kollias, Spyros S.

    2004-01-01

    The application of functional magnetic resonance imaging (fMRI) in studies of the visual system provided significant advancement in our understanding of the organization and functional properties of visual areas in the human cortex. Recent technological and methodological improvements allowed studies to correlate neuronal activity with visual perception and demonstrated the ability of fMRI to observe distributed neural systems and to explore modulation of neural activity during higher cognitive processes. Preliminary applications in patients with visual impairments suggest that this method provides a powerful tool for the assessment and management of brain pathologies. Recent research focuses on obtaining new information about the spatial localization, organization, functional specialization and participation in higher cognitive functions of visual cortical areas in the living human brain and in further establishment of the method as a useful clinical tool of diagnostic and prognostic significance for various pathologic processes affecting the integrity of the visual system. It is anticipated that the combined neuroimaging approach in patients with lesions and healthy controls will provide new insight on the topography and functional specialization of cortical visual areas and will further establish the clinical value of the method for improving diagnostic accuracy and treatment planning

  16. Investigation of stroke in sickle cell disease by 1H nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Wang, Z.; Bogdan, A.R.; Zimmermann, R.A.; Gusnard, D.A.; Leigh, J.S.; Ohene-Frempong, K.

    1992-01-01

    Localized proton nuclear magnetic resonance spectroscopy (MRS), obtained with stimulated echo and spin echo sequences, MR imaging (MRI) and MR angiography (MRA) were used to study the brain in 13 children and adolescents with sickle cell disease. Regions of interest (ROI) studied by MRS included regions appearing normal on MRI as well as regions showing complications of sickle cell disease, including focal deep white matter areas of high signal intensity (deep white matter ischemia, DWMI) seen on long TR images, focal atropic brain areas, and infarcts. The findings in these studies are summarized as follows: Normal-appearing regions on MRI have normal MRS. In ROI including small areas of DWMI, lactate elevation was not detected, but the levels of N-acetyl-aspartate (NAA) appeared slightly elevated. In areas of DWMI 1-2 cm in size, reduced blood flow could be seen on MRA and lactate elevation could be detected with MRS. When blood flow to a DWMI region was normal, NAA was reduced and there was little lactate elevation, as cell death had already occurred. ROI consisting of atrophic tissue had reduced NAA levels but total creatine levels were not changed. Sometimes lipids, presumably from broken cell membrane, could be detected. In regions of past massive stroke, all metabolites were absent except for small amounts of lactate or lipids. (orig.)

  17. Noncontrast Magnetic Resonance Lymphography.

    Science.gov (United States)

    Arrivé, Lionel; Derhy, Sarah; El Mouhadi, Sanaâ; Monnier-Cholley, Laurence; Menu, Yves; Becker, Corinne

    2016-01-01

    Different imaging techniques have been used for the investigation of the lymphatic channels and lymph glands. Noncontrast magnetic resonance (MR) lymphography has significant advantages in comparison with other imaging modalities. Noncontrast MR lymphography uses very heavily T2-weighted fast spin echo sequences which obtain a nearly complete signal loss in tissue background and specific display of lymphatic vessels with a long T2 relaxation time. The raw data can be processed with different algorithms such as maximum intensity projection algorithm to obtain an anatomic representation. Standard T2-weighted MR images easily demonstrate the location of edema. It appears as subcutaneous infiltration of soft tissue with a classical honeycomb pattern. True collection around the muscular area may be demonstrated in case of severe lymphedema. Lymph nodes may be normal in size, number, and signal intensity; in other cases, lymph nodes may be smaller in size or number of lymph nodes may be restricted. MR lymphography allows a classification of lymphedema in aplasia (no collecting vessels demonstrated); hypoplasia (a small number of lymphatic vessels), and numerical hyperplasia or hyperplasia (with an increased number of lymphatic vessels of greater and abnormal diameter). Noncontrast MR lymphography is a unique noninvasive imaging modality for the diagnosis of lymphedema. It can be used for positive diagnosis, differential diagnosis, and specific evaluation of lymphedema severity. It may also be used for follow-up evaluation after treatment. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  18. Magnetic resonance instrumentation

    International Nuclear Information System (INIS)

    Bell, R.A.

    1987-01-01

    Magnetic resonance (MR), while opening new vistas to diagnostic medicine, utilizes equipment that is unfamiliar to most clinicians. Beyond learning to cope with new terms, such as spin-echo, T1, T2, and spin density, health care professionals are faced with the inclusion of magnetic and radiofrequency effects in their facilities produced by a complex array of devices. It is the purpose of this chapter to outline the components of an MR imaging system, to discuss their functions, and to note the variations in equipment commercially available

  19. The administration of psilocybin to healthy, hallucinogen-experienced volunteers in a mock-functional magnetic resonance imaging environment: a preliminary investigation of tolerability.

    Science.gov (United States)

    Carhart-Harris, Robin L; Williams, Tim M; Sessa, Ben; Tyacke, Robin J; Rich, Ann S; Feilding, Amanda; Nutt, David J

    2011-11-01

    This study sought to assess the tolerability of intravenously administered psilocybin in healthy, hallucinogen-experienced volunteers in a mock-magnetic resonance imaging environment as a preliminary stage to a controlled investigation using functional magnetic resonance imaging to explore the effects of psilocybin on cerebral blood flow and activity. The present pilot study demonstrated that up to 2 mg of psilocybin delivered as a slow intravenous injection produces short-lived but typical drug effects that are psychologically and physiologically well tolerated. With appropriate care, this study supports the viability of functional magnetic resonance imaging work with psilocybin.

  20. Magnetic resonance imaging

    International Nuclear Information System (INIS)

    Sigal, R.

    1988-01-01

    This book is an introduction to magnetic resonance imaging (MRI). The basic principles for the interpretation of MR images are developed. The book is divided into five chapters: introduction, tissue, parameters, acquisition parameters, contribution to diagnosis, and practical management of an MR examination. Eight exercises allow the reader to test the knowledge he has acquired. Signal localization and MR artefacts are reviewed in an appendix

  1. Magnetic resonance imaging (MRI

    Directory of Open Access Journals (Sweden)

    Takavar A

    1993-04-01

    Full Text Available Basic physical principles of nuclear magnetic resonance imaging (N.M.R.I, a nonionizing medical imaging technique, are described. Principles of NMRI with other conventional imaging methods, ie, isotope scanning, ultrasonography and radiography have been compared. T1 and T2 and spin density (S.D. factors and different image construction techniques based on their different combinations is discussed and at the end physical properties of some N.M.R images is mentioned.

  2. Magnetic resonance imaging (MRI)

    OpenAIRE

    Takavar A

    1993-01-01

    Basic physical principles of nuclear magnetic resonance imaging (N.M.R.I), a nonionizing medical imaging technique, are described. Principles of NMRI with other conventional imaging methods, ie, isotope scanning, ultrasonography and radiography have been compared. T1 and T2 and spin density (S.D.) factors and different image construction techniques based on their different combinations is discussed and at the end physical properties of some N.M.R images is mentioned.

  3. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... magnetic resonance imaging (MRI) uses a powerful magnetic field, radio waves and a computer to produce detailed ... problems, medications, recent surgeries and allergies. The magnetic field is not harmful, but it may cause some ...

  4. Etiopathophysiological assessment of cases with chronic daily headache: A functional magnetic resonance imaging included investigation

    Science.gov (United States)

    Hashemi, Akram; Nami, Mohammad Torabi; Oghabian, Mohammad Ali; Ganjgahi, Habib; Vahabi, Zahra

    2012-01-01

    Background Chronic daily headache (CDH) has gained little attention in functional neuro-imaging. When no structural abnormality is found in CDH, defining functional correlates between activated brain regions during headache bouts may provide unique insights towards understanding the pathophysiology of this type of headache. Methods We recruited four CDH cases for comprehensive assessments, including history taking, physical examinations and neuropsychological evaluations (The Addenbrooke's Cognitive Evaluation, Beck's Anxiety and Depression Inventories, Pittsburg Sleep Quality Index and Epworth Sleepiness Scale). Visual analogue scale (VAS) was used to self-rate the intensity of headache. Patients then underwent electroencephalography (EEG), transcranial Doppler (TCD) and functional magnetic resonance imaging (fMRI) evaluations during maximal (VAS = 8-10/10) and off-headache (VAS = 0-3/10) conditions. Data were used to compare in both conditions. We also used BOLD (blood oxygen level dependent) -group level activation map fMRI to possibly locate headache-related activated brain regions. Results General and neurological examinations as well as conventional MRIs were unremarkable. Neuropsychological assessments showed moderate anxiety and depression in one patient and minimal in others. Unlike three patients, maximal and off-headache TCD evaluation in one revealed increased middle cerebral artery blood flow velocity, at the maximal pain area. Although with no seizure history, the same patient's EEG showed paroxysmal epileptic discharges during maximal headache intensity, respectively. Group level activation map fMRI showed activated classical pain matrix regions upon headache bouts (periaqueductal grey, substantia nigra and raphe nucleus), and markedly bilateral occipital lobes activation. Conclusion The EEG changes were of note. Furthermore, the increased BOLD signals in areas outside the classical pain matrix (i.e. occipital lobes) during maximal headaches may

  5. Magnetic resonance imaging: hazard, risk and safety

    International Nuclear Information System (INIS)

    Narayan, Pradeep; Suri, S.; Singh, P.

    2001-01-01

    The hazard and risk associated with magnetic resonance imaging is a matter of concern. In 1982, the Food and Drug Administration (FDA), USA issued guidelines to Hospital's Investigational Review Board (IRBs) in 'Guidelines for Evaluating Electromagnetic Exposure Risks for Trials of Clinical Nuclear Magnetic Resonance (NMR)'. In 1997, the Berufsgenossenschaft (BG), professional association for precision engineering and electronics of Germany, in their preliminary proposal for safety limits extended their concerns on static magnetic field. Owing to both time varying and static magnetic fields applied in Magnetic Resonance Imaging (MRI) this became of immediate concern to user community to assess the potential hazard and risk associated with the NMR system

  6. Magnetic resonance imaging of the prostate

    DEFF Research Database (Denmark)

    Iversen, P; Kjaer, L; Thomsen, C

    1988-01-01

    Magnetic resonance imaging offers new possibilities in investigation of the prostate gland. Current results of imaging and tissue discrimination in the evaluation of prostatic disease are reviewed. Magnetic resonance imaging may be useful in the staging of carcinoma of the prostate....

  7. Magnetic resonance imaging of the prostate

    DEFF Research Database (Denmark)

    Iversen, P; Kjaer, L; Thomsen, C

    1987-01-01

    Magnetic resonance imaging offers new possibilities in the investigation of the prostate. The current results of imaging and tissue discrimination in the evaluation of prostatic disease are reviewed. Magnetic resonance imaging may be of value in the staging of carcinoma of the prostate....

  8. Contrast agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Karadjian, V.

    1987-01-01

    The origine of nuclear magnetic resonance signal is reminded and different ways for contrast enhancement in magnetic resonance imaging are presented, especially, modifications of tissus relaxation times. Investigations have focused on development of agents incorporating either paramagnetic ions or stable free radicals. Pharmacological and toxicological aspects are developed. The diagnostic potential of these substances is illustrated by the example of gadolinium complexes [fr

  9. Introduction lecture to magnetic resonance

    International Nuclear Information System (INIS)

    Conard, J.

    1980-01-01

    This lecture deals with all that is common either to electron paramagnetic resonance (E.P.R.) or to nuclear magnetic resonance (N.M.R.). It will present, in an as elementary form as possible, the main concepts used in magnetic resonance emphasizing some aspects, specific for interface science. (orig./BHO)

  10. Magnetic properties of Fe/ZnSe and Fe/GaAs heterostructures investigated by ferromagnetic resonance and SQUID measurements

    Czech Academy of Sciences Publication Activity Database

    Meckenstock, R.; Spodding, D.; Himmelbauer, K.; Krenn, H.; Doi, M.; Keune, W.; Frait, Zdeněk; Pelzl, J.

    2002-01-01

    Roč. 240, - (2002), s. 410-413 ISSN 0304-8853 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic resonance * squid * anisotropy-growth-induced * relaxation-magnetic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.046, year: 2002

  11. Advanced Nuclear Magnetic Resonance

    OpenAIRE

    Alonso, Diego A.

    2014-01-01

    Transparencias en inglés de la asignatura "Resonancia Magnética Nuclear Avanzada" (Advanced Nuclear Magnetic Resonance) (36643) que se imparte en el Máster de Química Médica como asignatura optativa de 3 créditos ECTS. En esta asignatura se completa el estudio iniciado en la asignatura de quinto curso de la licenciatura en Química "Determinación estructural" (7448) y en la del Grado de Química de tercer curso "Determinación estructural de los compuestos orgánicos" (26030) en lo referente a té...

  12. Cranial magnetic resonance imaging

    International Nuclear Information System (INIS)

    Elster, A.D.

    1988-01-01

    Cranial Magnetic Resonance Imaging is comprehensive, well structured, and well written. The material is current and well referenced. The illustrations are good and complement the text well. The overall quality of publication is above average. The greatest attribute of the book is its readability. The author demonstrates ample skill in making complex subjects, such as MR physics and imaging of cerebral hemorrhage, easy to understand. The book closes with a detailed atlas on the anatomic appearance of the brain on MR images in the axial, coronal, and sagittal planes

  13. Dental magnetic resonance imaging

    International Nuclear Information System (INIS)

    Hilgenfeld, Tim; Bendszus, Martin; Haehnel, Stefan

    2016-01-01

    Growing distribution and utilization of digital volume tomography (DVT) extend the spectrum of clinical dental imaging. Additional diagnostic value, however, comes along with an increasing amount of radiation. In contrast, magnetic resonance imaging is a radiation free imaging technique. Furthermore, it offers a high soft tissue contrast. Morphological and numerical dental anomalies, differentiation of periapical lesions and exclusion of complications of dental diseases are field of applications for dental MRI. In addition, detection of caries and periodontal lesions and injury of inferior alveolar nerve are promising application areas in the future.

  14. Nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Cremin, B.J.

    1981-01-01

    Recent advances in diagnostic imaging, have been the medical application of nuclear magnetic resonance (NMR). It's been used to study the structure of various compounds in chemistry and physics, and in the mid-1970 to produce images of rabbits and eventually of the human hand and head. The images are produced by making use of the nuclear magnetization of the hydrogen ion, or proton, that is present in biological material to record the density distribution of protons in cellular water and lipids. An exploration of the end-results of complicated free induction decay signals, that have been digitized and frequency-analysed by mathematical computerized techniques to produce an image of tissue density, is given. At present NMR produces images comparable to those of early computed tomography

  15. Advances in magnetic resonance 11

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 11, presents a variety of contributions to the theory and practice of magnetic resonance. The book contains three chapters and begins with a discussion of the principles and applications of dynamic nuclear polarization, with emphasis on molecular motions and collisions, intermolecular couplings, and chemical interactions. Subsequent chapters focus on the assessment of a proposed broadband decoupling method and studies of time-domain (or Fourier transform) multiple-quantum nuclear magnetic resonance.

  16. Nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Rabenstein, D.L.; Guo, W.

    1988-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most widely used instrumental methods, with applications ranging from the characterization of pure compounds by high-resolution NMR to the diagnosis of disease by magnetic resonance imaging (MRI). To give some idea of the wide-spread use of NMR, a computer search for the period 1985-1987 turned up over 500 books and review articles and over 7000 literature citations, not including papers in which NMR was used together with other spectroscopic methods for the routine identification of organic compounds. Consequently, they have by necessity been somewhat selective in the topics they have chosen to cover and in the articles they have cited. In this review, which covers the published literature for the approximate period Sept 1985-Aug 1987, they have focused on new developments and applications of interest to the chemist. First they review recent developments in instrumentation and techniques. Although there have not been any major break-throughs in NMR instrumentation during the past two years, significant refinements have been reported which optimize instrumentation for the demanding multiple pulse experiments in routine use today. Next they review new developments in methods for processing NMR data, followed by reviews of one-dimensional and two-dimensional NMR experiments

  17. A functional magnetic resonance imaging investigation of short-term source and item memory for negative pictures.

    Science.gov (United States)

    Mitchell, Karen J; Mather, Mara; Johnson, Marcia K; Raye, Carol L; Greene, Erich J

    2006-10-02

    We investigated the hypothesis that arousal recruits attention to item information, thereby disrupting working memory processes that help bind items to context. Using functional magnetic resonance imaging, we compared brain activity when participants remembered negative or neutral picture-location conjunctions (source memory) versus pictures only. Behaviorally, negative trials showed disruption of short-term source, but not picture, memory; long-term picture recognition memory was better for negative than for neutral pictures. Activity in areas involved in working memory and feature integration (precentral gyrus and its intersect with superior temporal gyrus) was attenuated on negative compared with neutral source trials relative to picture-only trials. Visual processing areas (middle occipital and lingual gyri) showed greater activity for negative than for neutral trials, especially on picture-only trials.

  18. Comparison between digital subtraction angiography and magnetic resonance angiography in investigation of nonlacunar ischemic stroke in young patients: preliminary results.

    Science.gov (United States)

    Conforto, Adriana Bastos; Fregni, Felipe; Puglia, Paulo; Leite, Claudia da Costa; Yamamoto, Fabio Iuji; Coracini, Karen F; Scaff, Milberto

    2006-06-01

    We preliminarily investigated the relevance of performing digital subtraction angiography (DSA) in addition to magnetic resonance angiography (MRA) in definition of ischemic stroke etiology in young patients. DSAs and MRAs from 17 young patients with nonlacunar ischemic stroke were blindly analyzed and their impact on stroke management was evaluated. Etiologies were the same considering results of either DSA or MRA in 12/17 cases. In 15/17 patients no changes would have been made in treatment, regardless of the modality of angiography considered. These preliminary results suggest that DSA may be redundant in two thirds of ischemic strokes in young patients. Further larger prospective studies are necessary to determine indications of DSA in this age group.

  19. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... immediately after the exam. A few patients experience side effects from the contrast material, including nausea and local ... Related Articles and Media Catheter Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's (Pediatric) CT (Computed Tomography) Magnetic ...

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... by the interpreting radiologist. Frequently, the differentiation of abnormal (diseased) tissue from normal tissues is better with ... Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic ...

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Related Articles and Media Catheter Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's (Pediatric) CT (Computed Tomography) Magnetic ... the possible charges you will incur. Web page review process: This Web page is reviewed regularly by ...

  2. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Directory of Open Access Journals (Sweden)

    Fredén Jansson KJ

    2015-10-01

    Full Text Available Karl-Johan Fredén Jansson,1 Bo Håkansson,1 Sabine Reinfeldt,1 Cristina Rigato,1 Måns Eeg-Olofsson2 1Department of Signals and Systems, Chalmers University of Technology, 2Deptartment of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Purpose: The objective of this pilot study was to investigate if an active bone conduction implant (BCI used in an ongoing clinical study withstands magnetic resonance imaging (MRI of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO, total harmonic distortion (THD, and demagnetization were investigated. Implant activation and image artifacts were also evaluated.Methods and materials: One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI.Results: It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant.Conclusion: This pilot study indicates that the present BCI

  3. Nuclear magnetic resonance facility for investigation of a disk of the body

    International Nuclear Information System (INIS)

    Clow, H.; Walters, P.E.

    1979-01-01

    By means of the facility there can be determined the distribution of the water content or of the relaxation-time constants in cross-sectional deils or volumes of the patient. The magnetic field applied is described in form of pulses. In order to achieve the required equal field integrals there is performed an inquiry on the magnetic field at times predetermined for the gradient-pulse shape. The gradient-pulse shape itself is sinusoidal or deformed-sinusoidal. In the circuit for field measurement and error signal there are used Yttrium-Iron-Garnet (YIG) oscillator probes. (RW) [de

  4. Sum rules application to reflectometry of X-ray resonant radiation for magnetic multilayer investigation

    International Nuclear Information System (INIS)

    Smekhova, A.G.; Andreeva, M.A.

    2005-01-01

    One elaborated the general formalism on the basis of which one derived the clear expressions for reflection factors of X-ray radiation with a circular polarization from medium magnetized both within surface plane and within reflection plane both for grazing angles and for high grazing angles. The asymmetry of reflection spectra for right- and left-polarized radiation is shown to depend both on nondiagonal components of a susceptibility tensor and on other components in contrast to absorption spectra, so the sum rule to determine the orbital and the spin magnetic moments can not be applied directly to the experimental spectra of reflection [ru

  5. Solid-state 27Al nuclear magnetic resonance investigation of three aluminum-centered dyes

    KAUST Repository

    Mroué , Kamal H.; Emwas, Abdul-Hamid M.; Power, William P.

    2010-01-01

    on the aluminum electric field gradient (EFG) and nuclear magnetic shielding tensors. The quadrupolar parameters for each 27Al site were determined from spectral simulations, with quadrupolar coupling constants (CQ) ranging from 5.40 to 10.0 MHz and asymmetry

  6. NMR magnetic field controller for pulsed nuclear magnetic resonance experiments

    International Nuclear Information System (INIS)

    Scheler, G.; Anacker, M.

    1975-01-01

    A nuclear magnetic resonance controller for magnetic fields, which can also be used for pulsed NMR investigations, is described. A longtime stability of 10 -7 is achieved. The control signal is generated by a modified time sharing circuit with resonance at the first side band of the 2 H signal. An exact calibration of the magnetic field is achieved by the variation of the H 1 - or of the time-sharing frequency. (author)

  7. Magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Meyerhoff, D.J.; Weiner, M.W.

    1989-01-01

    A major function of the liver is regulation of carbohydrate, lipid, and nitrogen metabolism. Food is absorbed by the intestines and transported to the liver by the portal circulation. Substrates are metabolized and stored in the liver to maintain optimal blood concentrations of glucose and lipids. Ammonia generated in the gastrointestinal tract is converted to urea in the liver by the urea cycle. Various forms of liver disease are associated with disorders of carbohydrate, fat, and nitrogen metabolism. Therefore the ability to characterize liver metabolism noninvasively is of potential diagnostic value. Magnetic resonance spectroscopy (MRS) provides information about tissue metabolism by measuring concentrations of metabolites. However, to determine the anatomic location from which spectroscopic signals are derived, MRS could be performed in conjunction with MRI. This paper summarizes the current experience with spectroscopy ion animal models of human disease and reviews the clinical experience with hepatic MRS to date

  8. Magnetic resonance in neuroborreliosis

    International Nuclear Information System (INIS)

    Ustymowicz, A.; Zajkowska, J.

    2003-01-01

    Magnetic resonance (MR) is commonly used in diagnosing infections of the central nervous system. The aim of the study is to evaluate central nervous system changes in neuroborreliosis patients. MR examinations were performed in 44 patients with clinical symptoms, epidemiology and laboratory tests results of neuroborreliosis. Abnormalities were detected in 22 patients. Most of them presented cortico-subcortical atrophy (86%). In 9 cases foci of increased signal in T2-weighted and FLAIR images were observed in white matter. They were single or multiple, located subcorticaly and paraventriculary. In 2 subjects areas of increased signal were found in the brain stem. Central nervous system abnormalities detected with MR are not specific for Lyme disease. They can suggest demyelinating lesions and/or gliosis observed in many nervous system disorders (SM, ADEM, lacunar infarcts). (author)

  9. Cine magnetic resonance

    International Nuclear Information System (INIS)

    Higgins, C.B.; Sechtem, U.P.; Pflugfelder, P.

    1987-01-01

    Cine magnetic resonance (MR) is a fast MR imaging process with referencing of the imaging data to the electrocardiogram (ECG) so that images corresponding to 21-msec segments of the cardiac cycle are acquired. A series of such images, each corresponding to a 21-msec segment of the cardiac cycle, can be laced together for viewing in the cine format at a framing rate of 20 to 40 frames per second. Since cine angiograms of the heart are usually done at 30 frames per second, this technique achieves a temporal resolution adequate for the evluation of central cardiovascular function. The major application of this technique is to depict central cardiovascular function and blood flow

  10. An investigation of the performance of a coaxial HPGe detector operating in a magnetic resonance imaging field

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, L.J., E-mail: ljh@ns.ph.liv.ac.u [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Boston, A.J.; Boston, H.C.; Cole, P.; Cresswell, J.R.; Filmer, F.; Jones, M.; Judson, D.S.; Nolan, P.J.; Oxley, D.C.; Sampson, J.A.; Scraggs, D.P.; Slee, M.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Bimson, W.E.; Kemp, G.J. [MARIARC, University of Liverpool, Liverpool L69 3GE (United Kingdom); Groves, J.; Headspith, J.; Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Cooper, R.J. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States)

    2011-05-11

    Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such a device could provide a more complete medical insight into the functions of the body within a well-defined structural context. However, acquiring simultaneous nuclear/MRI sequences are technically challenging due to the conventional photomultiplier tube readout employed by most existing scintillator detector systems. A promising solution is a nuclear imaging device composed of semiconductor detectors that can be operated with a standard MRI scanner. However, the influence of placing a semiconductor detector such as high purity germanium (HPGe) within or close to the bore of an MRI scanner, where high magnetic fields are present, is not well understood. In this paper, the performance of a HPGe detector operating in a high strength static (B{sub S}) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the B{sub S} field on the energy resolution of the detector has been investigated for various positions and orientations of the detector within the magnetic field. The results have then been interpreted in terms of the influence of the B{sub S} field on the charge collection properties. MRI images have been acquired with the detector situated at the entrance of the MRI bore to investigate the effects of simultaneous data acquisition on detector performance and MRI imaging.

  11. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) uses a powerful ... for an MRI exam contains a metal called gadolinium . Gadolinium can be used in patients with iodine ...

  12. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... work? Unlike conventional x-ray examinations and computed tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, ... Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's (Pediatric) CT (Computed Tomography) Magnetic Resonance Imaging (MRI) Safety Contrast Materials Children ...

  13. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance Imaging Children’s magnetic resonance imaging (MRI) uses ... identify and accurately characterize diseases than other imaging methods. This detail makes MRI an invaluable tool in ...

  14. Magnetic resonance of low dimensional magnetic solids

    Energy Technology Data Exchange (ETDEWEB)

    Gatteschi, D.; Ferraro, F.; Sessoli, R. (Florence Univ. (Italy))

    1994-06-01

    The utility of EPR and NMR in the study of low-dimensional magnetic solids is shown. A short summary of the basis of magnetic resonance in these systems is reported, and the importance of spin-diffusion and magnetic anisotropy evidenced. Some results from experiments on metal-radical chains and clusters are presented. (authors). 37 refs., 7 figs.

  15. Magnetic resonance of low dimensional magnetic solids

    International Nuclear Information System (INIS)

    Gatteschi, D.; Ferraro, F.; Sessoli, R.

    1994-01-01

    The utility of EPR and NMR in the study of low-dimensional magnetic solids is shown. A short summary of the basis of magnetic resonance in these systems is reported, and the importance of spin-diffusion and magnetic anisotropy evidenced. Some results from experiments on metal-radical chains and clusters are presented. (authors). 37 refs., 7 figs

  16. Advances in magnetic resonance 12

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 12, presents a variety of contributions to the theory and practice of magnetic resonance. The book contains six chapters and begins with a discussion of diffusion and self-diffusion measurements by nuclear magnetic resonance. This is followed by separate chapters on spin-lattice relaxation time in hydrogen isotope mixtures; the principles of optical detection of nuclear spin alignment and nuclear quadropole resonance; and the spin-1 behavior, including the relaxation of the quasi-invariants of the motion of a system of pairs of dipolar coupled spin-1/2 nu

  17. Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt2In7 using magnetic resonant x-ray diffraction

    Science.gov (United States)

    Gauthier, Nicolas; Wermeille, Didier; Casati, Nicola; Sakai, Hironori; Baumbach, Ryan E.; Bauer, Eric D.; White, Jonathan S.

    2017-08-01

    We investigated the magnetic structure of the heavy-fermion compound CePt2In7 below TN=5.34 (2 ) K using magnetic resonant x-ray diffraction at ambient pressure. The magnetic order is characterized by a commensurate propagation vector k1 /2=(1/2 ,1/2 ,1/2 ) with spins lying in the basal plane. Our measurements did not reveal the presence of an incommensurate order propagating along the high-symmetry directions in reciprocal space but cannot exclude other incommensurate modulations or weak scattering intensities. The observed commensurate order can be described equivalently by either a single-k structure or by a multi-k structure. Furthermore we explain how a commensurate-only ordering may explain the broad distribution of internal fields observed in nuclear quadrupolar resonance experiments [Sakai et al., Phys. Rev. B 83, 140408 (2011), 10.1103/PhysRevB.83.140408] that was previously attributed to an incommensurate order. We also report powder x-ray diffraction showing that the crystallographic structure of CePt2In7 changes monotonically with pressure up to P =7.3 GPa at room temperature. The determined bulk modulus B0=81.1 (3 ) GPa is similar to those of the Ce-115 family. Broad diffraction peaks confirm the presence of pronounced strain in polycrystalline samples of CePt2In7 . We discuss how strain effects can lead to different electronic and magnetic properties between polycrystalline and single crystal samples.

  18. Magnetic resonance imaging methodology

    International Nuclear Information System (INIS)

    Moser, Ewald; Stadlbauer, Andreas; Windischberger, Christian; Quick, Harald H.; Ladd, Mark E.

    2009-01-01

    Magnetic resonance (MR) methods are non-invasive techniques to provide detailed, multi-parametric information on human anatomy, function and metabolism. Sensitivity, specificity, spatial and temporal resolution may, however, vary depending on hardware (e.g., field strength, gradient strength and speed) and software (optimised measurement protocols and parameters for the various techniques). Furthermore, multi-modality imaging may enhance specificity to better characterise complex disease patterns. Positron emission tomography (PET) is an interesting, largely complementary modality, which might be combined with MR. Despite obvious advantages, combining these rather different physical methods may also pose challenging problems. At this early stage, it seems that PET quality may be preserved in the magnetic field and, if an adequate detector material is used for the PET, MR sensitivity should not be significantly degraded. Again, this may vary for the different MR techniques, whereby functional and metabolic MR is more susceptible than standard anatomical imaging. Here we provide a short introduction to MR basics and MR techniques, also discussing advantages, artefacts and problems when MR hardware and PET detectors are combined. In addition to references for more detailed descriptions of MR fundamentals and applications, we provide an early outlook on this novel and exciting multi-modality approach to PET/MR. (orig.)

  19. Solid-state 27Al nuclear magnetic resonance investigation of three aluminum-centered dyes

    KAUST Repository

    Mroué, Kamal H.

    2010-02-01

    We report the first solid-state 27Al NMR study of three aluminum phthalocyanine dyes: aluminum phthalocyanine chloride, AlPcCl (1); aluminum-1,8,15,22-tetrakis(phenylthio)-29H,31H-phthalocyanine chloride, AlPc(SPh)4Cl (2); and aluminum-2,3-naphthalocyanine chloride, AlNcCl (3). Each of these compounds contains Al3+ ions coordinating to four nitrogen atoms and a chlorine atom. Solid-state 27Al NMR spectra, including multiple-quantum magic-angle spinning (MQMAS) spectra and quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) spectra of stationary powdered samples have been acquired at multiple high magnetic field strengths (11.7, 14.1, and 21.1 T) to determine their composition and number of aluminum sites, which were analyzed to extract detailed information on the aluminum electric field gradient (EFG) and nuclear magnetic shielding tensors. The quadrupolar parameters for each 27Al site were determined from spectral simulations, with quadrupolar coupling constants (CQ) ranging from 5.40 to 10.0 MHz and asymmetry parameters (η) ranging from 0.10 to 0.50, and compared well with the results of quantum chemical calculations of these tensors. We also report the largest 27Al chemical shielding anisotropy (CSA), with a span of 120 ± 10 ppm, observed directly in a solid material. The combination of MQMAS and computational predictions are used to interpret the presence of multiple aluminum sites in two of the three samples.

  20. Magnetic resonance imaging and computed tomography as tools for the investigation of sperm whale (Physeter macrocephalus) teeth and eye

    DEFF Research Database (Denmark)

    Alstrup, Aage Kristian Olsen; Munk, Ole Lajord; Jensen, Trine Hammer

    2017-01-01

    Background: Scanning techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) are useful tools in veterinary and human medicine. Here we demonstrate the usefulness of these techniques in the study of the anatomy of wild marine mammals as part of a necropsy. MRI and CT scan...

  1. Magnetic resonance imaging in psychiatry

    International Nuclear Information System (INIS)

    Mann, K.

    1993-01-01

    Diagnosis and research in psychiatry are increasingly availing themselves of magnetic resonance imaging (MRI). In comparison to computed tomography (CT), this offers the combined benefits of no exposure to radiation, high resolution, artefact-free display of structures near bone, and a sharp contrast between the grey and white brain matter, with freedom to select the section. With the exception of very anxious patients, MRI will gradually replace CT scans for a wide range of differential diagnostic investigations. Its superiority in systematic studies of psychiatric patients with discrete cerebral parenchyma lesions is already considered proven. This is illustrated on the basis of research into schizophrenia and alcoholism. (orig.) [de

  2. Low field magnetic resonance imaging

    Science.gov (United States)

    Pines, Alexander; Sakellariou, Dimitrios; Meriles, Carlos A.; Trabesinger, Andreas H.

    2010-07-13

    A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.

  3. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Science.gov (United States)

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    Purpose The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. Methods and materials One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. Results It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. Conclusion This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant. PMID:26604836

  4. Magnetic resonance imaging investigation of the bone conduction implant - a pilot study at 1.5 Tesla.

    Science.gov (United States)

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant.

  5. Investigation on the neurobiological correlates of social anxiety disorder using functional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Sladky, R.

    2012-01-01

    Functional MRI is based on the very intuitive principle that neuronal activity leads to locally increased energy demand, which can be measured due to the different magnetic properties of oxygenated and deoxygenated blood. Interdisciplinary research and development in MR physics, engineering, bioinformatics and neuroscience have made fMRI an indispensible research tool for all domains of cognitive science. Besides basic research, fMRI has become a gold standard diagnostic method for clinical applications, as well. The main goal of the present doctoral thesis was to contribute to the understanding of the neural mechanisms of social anxiety disorder (SAD) patients. SAD is a disabling psychiatric conditions that impairs social interactions and acts as a major risk factor for depression and addiction. To this end, an fMRI study has been conducted on a population of SAD patients and healthy controls to highlight functional aberrations within the emotion regulation network. Failed adaptation towards social stressors, such as emotional faces, is a characterizing symptom of SAD. And indeed, in this study, which involved an emotion discrimination task, group differences in neural habituation of SAD patients were found in the amygdala and the orbitofrontal cortex (OFC), two central nodes of the emotion regulation network. To highlight the causal neurobiological mechanisms, the same data were analyzed using dynamic causal modeling (DCM). In this study, a difference in effective connectivity between the OFC and the amygdala was found. In healthy subjects, the OFC showed to down-regulate amygdalar activation, which corresponds to the conception of cognitive top-down control over affective influences. In SAD patients, however, a positive effective connectivity from OFC to amygdala was found, indicating a positive feedback loop between these regions. This finding, thus, nurtures a neurobiological model that could explain the decreased inhibition of affective stimuli by cognitive

  6. The Role of Reward Expectations for Prospective Memory : An investigation with functional magnetic resonance imaging

    OpenAIRE

    Gäbel, Andrea

    2010-01-01

    Prospective memory is the ability to remember to carry out an intended action after a delay. However, it remains unclear how motivational aspects of the intended action,such as reward expectations, are integrated into the processes subserving intact prospective memory. The goal of this dissertation is to investigate the effects of motivational incentives on prospective memory on the behavioral and on the neural level, while taking into account individual differences in reward sensitivity and ...

  7. Rigor mortis at the myocardium investigated by post-mortem magnetic resonance imaging.

    Science.gov (United States)

    Bonzon, Jérôme; Schön, Corinna A; Schwendener, Nicole; Zech, Wolf-Dieter; Kara, Levent; Persson, Anders; Jackowski, Christian

    2015-12-01

    Post-mortem cardiac MR exams present with different contraction appearances of the left ventricle in cardiac short axis images. It was hypothesized that the grade of post-mortem contraction may be related to the post-mortem interval (PMI) or cause of death and a phenomenon caused by internal rigor mortis that may give further insights in the circumstances of death. The cardiac contraction grade was investigated in 71 post-mortem cardiac MR exams (mean age at death 52 y, range 12-89 y; 48 males, 23 females). In cardiac short axis images the left ventricular lumen volume as well as the left ventricular myocardial volume were assessed by manual segmentation. The quotient of both (LVQ) represents the grade of myocardial contraction. LVQ was correlated to the PMI, sex, age, cardiac weight, body mass and height, cause of death and pericardial tamponade when present. In cardiac causes of death a separate correlation was investigated for acute myocardial infarction cases and arrhythmic deaths. LVQ values ranged from 1.99 (maximum dilatation) to 42.91 (maximum contraction) with a mean of 15.13. LVQ decreased slightly with increasing PMI, however without significant correlation. Pericardial tamponade positively correlated with higher LVQ values. Variables such as sex, age, body mass and height, cardiac weight and cause of death did not correlate with LVQ values. There was no difference in LVQ values for myocardial infarction without tamponade and arrhythmic deaths. Based on the observation in our investigated cases, the phenomenon of post-mortem myocardial contraction cannot be explained by the influence of the investigated variables, except for pericardial tamponade cases. Further research addressing post-mortem myocardial contraction has to focus on other, less obvious factors, which may influence the early post-mortem phase too. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Parallel magnetic resonance imaging

    International Nuclear Information System (INIS)

    Larkman, David J; Nunes, Rita G

    2007-01-01

    Parallel imaging has been the single biggest innovation in magnetic resonance imaging in the last decade. The use of multiple receiver coils to augment the time consuming Fourier encoding has reduced acquisition times significantly. This increase in speed comes at a time when other approaches to acquisition time reduction were reaching engineering and human limits. A brief summary of spatial encoding in MRI is followed by an introduction to the problem parallel imaging is designed to solve. There are a large number of parallel reconstruction algorithms; this article reviews a cross-section, SENSE, SMASH, g-SMASH and GRAPPA, selected to demonstrate the different approaches. Theoretical (the g-factor) and practical (coil design) limits to acquisition speed are reviewed. The practical implementation of parallel imaging is also discussed, in particular coil calibration. How to recognize potential failure modes and their associated artefacts are shown. Well-established applications including angiography, cardiac imaging and applications using echo planar imaging are reviewed and we discuss what makes a good application for parallel imaging. Finally, active research areas where parallel imaging is being used to improve data quality by repairing artefacted images are also reviewed. (invited topical review)

  9. Magnetic resonance imaging. 1

    International Nuclear Information System (INIS)

    Wall, E.E. van der; Roos, A.A. de; Doornbos, J.; Dijkman, P.R.M. van; Matheijssen, N.A.A.; Laarse, A. van der; Krauss, X.H.; Blokland, J.A.k.; Manger Cats, V.; Voorthuisen, A.E. van; Bruschke, A.V.G.

    1991-01-01

    The cardiovascular applications of MRI in coronary artery disease have considerably increased in recent years. Although many applications overlap those of other more cost-effective techniques, such as echocardiography, radionuclide angiography, and CT, MRI offers unique features not shared by the conventional techniques. Technical advantages are the excellent spatial resolution, the characterization of myocardial tissue, and the potential for three-dimensional imaging. This allows the accurate assessment of left ventricular mass and volume, the differentiation of infarcted tissue from normal myocardial tissue, and the determination of systolic wall thickening and regional wall motion abnormalities. Also inducible myocardial ischemia using pharmacological stress (dipyramidole or dobutamine) may be assessed by magnetic resonance imaging. Future technical developments include real-time imaging and noninvasive visualization of the coronary arteries. These advantages will have a major impact on the application of MRI in coronary artery disease, potentially unsurpassed by other techniques and certainly justifying the expenses. Consequently, the clinical use of MRI for the detection of coronary artery disease largely depends on the progress of technical developments. (author). 134 refs.; 10 figs.; 2 tabs

  10. Advances in magnetic resonance 9

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 9 describes the magnetic resonance in split constants and dipolar relaxation. This book discusses the temperature-dependent splitting constants in the ESR spectra of organic free radicals; temperature-dependent splittings in ion pairs; and magnetic resonance induced by electrons. The electron impact excitation of atoms and molecules; intramolecular dipolar relaxation in multi-spin systems; and dipolar cross-correlation problem are also elaborated. This text likewise covers the NMR studies of molecules oriented in thermotropic liquid crystals and diffusion

  11. Advances in magnetic resonance 1

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 1, discusses developments in various areas of magnetic resonance. The subject matter ranges from original theoretical contributions through syntheses of points of view toward series of phenomena to critical and painstaking tabulations of experimental data. The book contains six chapters and begins with a discussion of the theory of relaxation processes. This is followed by separate chapters on the development of magnetic resonance techniques for studying rate processes in chemistry and the application of these techniques to various problems; the geometri

  12. Investigation of proton spin relaxation in water with dispersed silicon nanoparticles for potential magnetic resonance imaging applications

    Science.gov (United States)

    Kargina, Yu. V.; Gongalsky, M. B.; Perepukhov, A. M.; Gippius, A. A.; Minnekhanov, A. A.; Zvereva, E. A.; Maximychev, A. V.; Timoshenko, V. Yu.

    2018-03-01

    Porous and nonporous silicon (Si) nanoparticles (NPs) prepared by ball-milling of electrochemically etched porous Si layers and crystalline Si wafers were studied as potential agents for enhancement of the proton spin relaxation in aqueous media. While nonporous Si NPs did not significantly influence the spin relaxation, the porous ones resulted in strong shortening of the transverse relaxation times. In order to investigate an effect of the electron spin density in porous Si NPs on the proton spin relaxation, we use thermal annealing of the NPs in vacuum or in air. The transverse relaxation rate of about 0.5 l/(g s) was achieved for microporous Si NPs, which were thermally annealing in vacuum to obtain the electron spin density of the order of 1017 g-1. The transverse relaxation rate was found to be almost proportional to the concentration of porous Si NPs in the range from 0.1 to 20 g/l. The obtained results are discussed in view of possible biomedical applications of Si NPs as contrast agents for magnetic resonance imaging.

  13. Temporal and spatial characteristics of the area at risk investigated using computed tomography and T1-weighted magnetic resonance imaging

    DEFF Research Database (Denmark)

    van der Pals, Jesper; Hammer-Hansen, Sophia; Nielles-Vallespin, Sonia

    2015-01-01

    AIMS: Cardiovascular magnetic resonance (CMR) imaging can measure the myocardial area at risk (AAR), but the technique has received criticism for inadequate validation. CMR commonly depicts an AAR that is wider than the infarct, which in turn would require a lateral perfusion gradient within...... and fluorescent microparticle pathology were used to investigate the AAR in a canine model (n = 10) of ischaemia and reperfusion. AAR size by CMR correlated well with CT (R(2) = 0.80), microsphere blood flow (R(2) = 0.80), and pathology (R(2) = 0.74) with good limits of agreement [-0.79 ± 4.02% of the left.......05 ± 0.02 mL/g/min, lateral vs. core, P = 0.001). The transmural extent of MI was lower in the lateral portion of the AAR than the core (28.2 ± 10.2 vs. 17.4 ± 8.4% of the wall, P = 0.001). CONCLUSION: T1-weighted CMR accurately quantifies size of the AAR with excellent agreement compared with three...

  14. A fluorescence detected magnetic resonance investigation of the carotenoid triplet states associated with Photosystem II of isolated spinach thylakoid membranes

    CERN Document Server

    Santabarbara, S; Carbonera, D; Heathcote, P

    2005-01-01

    The carotenoid triplet populations associated with the fluorescence emission chlorophyll forms of Photosystem II have been investigated in isolated spinach thylakoid membranes by means of fluorescence detected magnetic resonance in zero field (FDMR). The spectra collected in the 680-690 nm emission range, have been fitted by a global analysis procedure. At least five different carotenoid triplet states coupled to the terminal emitting chlorophyll forms of PS II, peaking at 682 nm, 687 nm and 692 nm, have been characterised. The triplets associated with the outer antenna emission forms, at 682 nm, have zero field splitting parameters D = 0.0385 cm/sup -1/, E = 0.00367 cm/sup -1/; D = 0.0404 cm/sup -1/, E = 0.00379 cm/sup -1/ and D = 0.0386 cm/sup -1/, E = 0.00406 cm/sup -1/ which are very similar to those previously reported for the xanthophylls of the isolated LHC II complex. Therefore the FDMR spectra recorded in this work provide insights into the organisation of the LHC II complex in the unperturbed enviro...

  15. Time-resolved three-dimensional magnetic resonance velocity mapping of chronic thoracic aortic dissection. A preliminary investigation

    International Nuclear Information System (INIS)

    Amano, Yasuo; Sekine, Tetsuro; Tanaka, Keiji; Takagi, Ryo; Kumita, Shinichiro; Suzuki, Yuriko

    2011-01-01

    The blood flow patterns of chronic thoracic aortic dissection are complicated, and their clinical significance remains unknown. We evaluated the technical and clinical potentials of time-resolved 3-dimensional (3D) magnetic resonance (MR) velocity mapping for assessing these patterns. We used data collected from time-resolved 3D phase-contrast MR imaging of 16 patients with chronic thoracic aortic dissection to generate time-resolved 3D MR velocity mapping that included 3D streamline and path line. We investigated blood flow patterns of this disease in the mapping and compared them with the morphological changes of the patent false lumen. Time-resolved 3D MR velocity mapping visualized rapid flow at the entry and in the true lumen immediately distal to the entry. We observed slower helical or laminar flow in the patent false lumen. In patients with disease progression, slower helical flow following rapid entry jet collided with the outer wall of the false lumen and was also observed in a growing ulcer-like projection. We showed the potential of time-resolved 3D MR velocity mapping for visualizing pathologic flow patterns related to chronic thoracic aortic dissection. (author)

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... is not harmful, but it may cause some medical devices to malfunction. Most orthopedic implants pose no ... Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... are the limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging ( ... brain) in routine clinical practice. top of page What are some common uses of the procedure? MR ...

  18. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... As the hydrogen atoms return to their usual alignment, they emit different amounts of energy that vary ... story about radiology? Share your patient story here Images × Image Gallery Radiologist prepping patient for magnetic resonance ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... As the hydrogen atoms return to their usual alignment, they emit different amounts of energy that vary ... story about radiology? Share your patient story here Images × Image Gallery Magnetic Resonance Imaging (MRI) procedure View ...

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... bear denotes child-specific content. Related Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain ... the web pages found at these links. About Us | Contact Us | FAQ | Privacy | Terms of Use | Links | ...

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... bear denotes child-specific content. Related Articles and Media Catheter Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's ( ... the web pages found at these links. About Us | Contact Us | FAQ | Privacy | Terms of Use | Links | ...

  2. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... or thyroid problems. Any of these conditions may influence the decision on whether contrast material will be ... bear denotes child-specific content. Related Articles and Media Catheter Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's ( ...

  3. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... it is useful to bring that to the attention of the technologist or scheduler before the exam. ... patient for magnetic resonance imaging (MRI) exam. View full size with caption Pediatric Content Some imaging tests ...

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... it is useful to bring that to the attention of the scheduler before the exam and bring ... Image Gallery Magnetic Resonance Imaging (MRI) procedure View full size with caption Pediatric Content Some imaging tests ...

  5. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... MRI) exam. View full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Related Articles and Media Catheter Angiography Magnetic Resonance, ...

  6. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow- ... necessary in trauma situations. Although there is no reason to believe that magnetic resonance imaging harms the ...

  7. Magnetic resonance imaging the basics

    CERN Document Server

    Constantinides, Christakis

    2014-01-01

    Magnetic resonance imaging (MRI) is a rapidly developing field in basic applied science and clinical practice. Research efforts in this area have already been recognized with five Nobel prizes awarded to seven Nobel laureates in the past 70 years. Based on courses taught at The Johns Hopkins University, Magnetic Resonance Imaging: The Basics provides a solid introduction to this powerful technology. The book begins with a general description of the phenomenon of magnetic resonance and a brief summary of Fourier transformations in two dimensions. It examines the fundamental principles of physics for nuclear magnetic resonance (NMR) signal formation and image construction and provides a detailed explanation of the mathematical formulation of MRI. Numerous image quantitative indices are discussed, including (among others) signal, noise, signal-to-noise, contrast, and resolution. The second part of the book examines the hardware and electronics of an MRI scanner and the typical measurements and simulations of m...

  8. Muscle fat content and abdominal adipose tissue distribution investigated by magnetic resonance spectroscopy and imaging in obese children and youths

    DEFF Research Database (Denmark)

    Fonvig, Cilius E; Bille, Dorthe S; Chabanova, Elizaveta

    2012-01-01

    The degree of fat deposition in muscle and its implications for obesity-related complications in children and youths are not well understood. One hundred and fifty-nine patients (mean age: 13.3 years; range: 6-20) with a body mass index (BMI) >90(th) percentile for age and sex were included. Muscle...... fat content (MFC) was measured in the psoas muscle by proton magnetic resonance spectroscopy. The patients were assigned to two groups: MFC...

  9. Magnetic Resonance Imaging. Chapter 15

    Energy Technology Data Exchange (ETDEWEB)

    Leach, M. O. [The Institute of Cancer Research and The Royal Marsden Hospital, London (United Kingdom)

    2014-09-15

    In Chapter 14, the principles of nuclear magnetic resonance were presented, along with an introduction to image forming processes. In this chapter, magnetic resonance imaging (MRI) will be reviewed, beginning with the hardware needed and its impact on image quality. The acquisition processes and image reconstruction will be discussed, as well as the artefacts that are possible, with discussion of the important area of safety and bioeffects completing the chapter.

  10. The nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Goyer, Ph.

    1997-01-01

    The spectroscopy of nuclear magnetic resonance constitutes a major analytical technique in biological and organic analysis. This technique appears now in the programme of preparatory classes and its teaching is developed in the second year of DEUG. The following article reviews on the nuclear magnetic resonance and on the possibilities it offers to bring to the fore the physico-chemical properties of molecules. (N.C.)

  11. Advances in magnetic resonance 2

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 2, features a mixture of experimental and theoretical contributions. The book contains four chapters and begins with an ambitious and general treatment of the problem of signal-to-noise ratio in magnetic resonance. This is followed by separate chapters on the interpretation of nuclear relaxation in fluids, with special reference to hydrogen; and various aspects of molecular theory of importance in NMR.

  12. Nuclear magnetic resonance diagnostic apparatus

    International Nuclear Information System (INIS)

    Sugimoto, H.

    1985-01-01

    Nuclear magnetic resonance diagnostic apparatus including a coil for generating a gradient field in a plane perpendicular to a static magnetic field, means for controlling the operation of the coil to rotationally shift in angular steps the gradient direction of the gradient field at an angle pitch of some multiple of the unit index angle through a plurality of rotations to assume all the shift positions of the gradient direction, a rough image reconstructor for reconstructing a rough tomographic image on the basis of nuclear magnetic resonance signals acquired during a rotation of the second gradient magnetic field, a rough image display for depicting the rough tomographic image, a final image reconstructor for reconstructing a final tomographic image on the basis of all nuclear magnetic resonance signals corresponding to all of the expected rotation shift positions acquired during a plurality of rotations and a final image display for depicting the final tomographic image

  13. Nuclear magnetic resonance and earth magnetic field

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Nuclear magnetic resonance concerns nuclei whose spin is different from 0. These nuclei exposed to a magnetic field is comparable to a peg top spinning around its axis while being moved by a precession movement called Larmor precession. This article presents an experiment whose aim is to reveal nuclear magnetism of nuclei by observing Larmor precession phenomena due to the earth magnetic field. The earth magnetic field being too weak, it is necessary to increase the magnetization of the sample during a polarization phase. First the sample is submitted to a magnetic field B perpendicular to the earth magnetic field B 0 , then B is cut off and the nuclei move back to their equilibrium position by executing a precession movement due to B 0 field. (A.C.)

  14. Stability of Mixed Preparations Consisting of Commercial Moisturizing Creams with an Ointment Base Investigated by Magnetic Resonance Imaging.

    Science.gov (United States)

    Onuki, Yoshinori; Funatani, Chiaki; Yamamoto, Yoshihisa; Fukami, Toshiro; Koide, Tatsuo; Hayashi, Yoshihiro; Takayama, Kozo

    2017-01-01

    A moisturizing cream mixed with a steroid ointment is frequently prescribed to patients suffering from atopic dermatitis. However, there is a concern that the mixing operation causes destabilization. The present study was performed to investigate the stability of such preparations closely using magnetic resonance imaging (MRI). As sample preparations, five commercial moisturizing creams that are popular in Japan were mixed with an ointment base, a white petrolatum, at a volume ratio of 1 : 1. The mixed preparations were stored at 60°C to accelerate the destabilization processes. Subsequently, the phase separations induced by the storage test were monitored using MRI. Using advanced MR technologies including spin-spin relaxation time (T 2 ) mapping and MR spectroscopy, we successfully characterized the phase-separation behavior of the test samples. For most samples, phase separations developed by the bleeding of liquid oil components. From a sample consisting of an oil-in-water-type cream, Urepearl Cream 10%, a distinct phase-separation mode was observed, which was initiated by the aqueous component separating from the bottom part of the sample. The resultant phase separation was the most distinct among the test samples. To investigate the phase separation quantitatively and objectively, we conducted a histogram analysis on the acquired T 2 maps. The water-in-oil type creams were found to be much more stable after mixing with ointment base than those of oil-in-water type creams. This finding strongly supported the validity of the mixing operation traditionally conducted in pharmacies.

  15. Magnetic resonance imaging of chemistry.

    Science.gov (United States)

    Britton, Melanie M

    2010-11-01

    Magnetic resonance imaging (MRI) has long been recognized as one of the most important tools in medical diagnosis and research. However, MRI is also well placed to image chemical reactions and processes, determine the concentration of chemical species, and look at how chemistry couples with environmental factors, such as flow and heterogeneous media. This tutorial review will explain how magnetic resonance imaging works, reviewing its application in chemistry and its ability to directly visualise chemical processes. It will give information on what resolution and contrast are possible, and what chemical and physical parameters can be measured. It will provide examples of the use of MRI to study chemical systems, its application in chemical engineering and the identification of contrast agents for non-clinical applications. A number of studies are presented including investigation of chemical conversion and selectivity in fixed-bed reactors, temperature probes for catalyst pellets, ion mobility during tablet dissolution, solvent dynamics and ion transport in Nafion polymers and the formation of chemical waves and patterns.

  16. Magnetic Resonance Imaging

    Science.gov (United States)

    ... Permanent cosmetics or tattoos Dentures/teeth with magnetic keepers Other implants that involve magnets Medication patch (i. ... or longer. You’ll be told ahead of time just how long your scan is expected to ...

  17. Magnetic resonance imaging in neuroradiology

    International Nuclear Information System (INIS)

    Voigt, K.; Lotx, J.W.

    1990-01-01

    Magnetic resonance imaging (MRI) is now accepted as an effective method of investigating a wide range of disorders, especially of the brain and spine. A short introduction on image contrast in MRI is given and the advantages and disadvantages for the different diseases of the brain is discussed. Excellent soft-tissue contrast, multiplanar imaging capabilities and lack of ionising radiation are conspicuous advantages, and it is now established as the investigation of choice in a large number of clinical conditions, especially when the central nervous system is involved. However, it remains only one of a series of imaging modalities. A confident provisional clinical diagnosis is essential for establishing an imaging protocol and the intention should always be to reach a definitive diagnosis in the least invasive and most cost-effective way. 7 figs., 19 refs

  18. Noble gas magnetic resonator

    Science.gov (United States)

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  19. Disc pathology after whiplash injury. A prospective magnetic resonance imaging and clinical investigation; Pathologie vertebrale apres le coup du lapin. Une investigation clinique et d` imagerie prospective par resonance magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, K.; Hildingsson, C.; Toolanen, G.; Fagerlund, M.; Bjornebrink, J. [University Hospital of Northem (Sweden)

    1997-09-01

    Although disc pathology seems to be one contributing factor in the development of chronic symptoms after whiplash injury, it may be unnecessary to examine these patients in the acute phase with magnetic resonance imaging ; correlating initial symptoms and signs to magnetic resonance imaging findings is difficult because of the relatively high proportion of false-positive results. Magnetic resonance imaging is indicated later in the course of treatment in patients with persistent arm pain, neurologic deficits, or clinical signs of nerve root compression to diagnose disc herniations requiring surgery. (authors).

  20. Indirect magnetic resonance arthrography of the shoulder; a reliable diagnostic tool for investigation of suspected labral pathology

    Energy Technology Data Exchange (ETDEWEB)

    Fallahi, Farshid [North Cumbria University Hospitals NHS Trust, Carlisle (United Kingdom); North Cumbria University Hospitals, Department of Radiology, Carlisle (United Kingdom); Green, Nick; Gadde, Sarat; Jeavons, Lisa; Armstrong, Patrick; Jonker, Leon [North Cumbria University Hospitals NHS Trust, Carlisle (United Kingdom)

    2013-09-15

    Indirect magnetic resonance arthrography (I-MRA) confers significant logistical advantages over direct MRA and does not require articular injection. In this study, we determined the diagnostic performance of I-MRA in relation to conventional MRI and arthroscopy or surgery in detecting tears of the glenoid labrum, including Bankart lesions and superior labral antero-posterior (SLAP) tears in a standard clinical setting. Ninety-one symptomatic patients underwent conventional MRI and I-MRA of the affected shoulder, followed by either arthroscopy or open surgery. The scans were interpreted independently by two experienced radiology consultants with a special interest in musculoskeletal radiology. Using the surgical findings as the standard of reference, sensitivity, specificity, and diagnostic accuracy of conventional non-contrast MRI and I-MRA in the detection of labral tears were calculated. The sensitivity of I-MRA was 95 and 97 %, respectively, for two radiologists as opposed to 79 and 83 % for conventional MRI. For both radiologists, the specificity of I-MRA, as well as MRI, was 91 % for detection of labral tears of all types. Accuracy of diagnosis was 93 and 95 %, respectively, for two radiologists with indirect MRA, compared to 84 and 86 % with non-contrast MRI. This retrospective study shows that I-MRA is a highly accurate and sensitive method for the detection of labral tears. The data obtained supports the use of I-MRA as standard practice in patients with shoulder instability due to suspected labral pathology where further investigative imaging is indicated. (orig.)

  1. Indirect magnetic resonance arthrography of the shoulder; a reliable diagnostic tool for investigation of suspected labral pathology

    International Nuclear Information System (INIS)

    Fallahi, Farshid; Green, Nick; Gadde, Sarat; Jeavons, Lisa; Armstrong, Patrick; Jonker, Leon

    2013-01-01

    Indirect magnetic resonance arthrography (I-MRA) confers significant logistical advantages over direct MRA and does not require articular injection. In this study, we determined the diagnostic performance of I-MRA in relation to conventional MRI and arthroscopy or surgery in detecting tears of the glenoid labrum, including Bankart lesions and superior labral antero-posterior (SLAP) tears in a standard clinical setting. Ninety-one symptomatic patients underwent conventional MRI and I-MRA of the affected shoulder, followed by either arthroscopy or open surgery. The scans were interpreted independently by two experienced radiology consultants with a special interest in musculoskeletal radiology. Using the surgical findings as the standard of reference, sensitivity, specificity, and diagnostic accuracy of conventional non-contrast MRI and I-MRA in the detection of labral tears were calculated. The sensitivity of I-MRA was 95 and 97 %, respectively, for two radiologists as opposed to 79 and 83 % for conventional MRI. For both radiologists, the specificity of I-MRA, as well as MRI, was 91 % for detection of labral tears of all types. Accuracy of diagnosis was 93 and 95 %, respectively, for two radiologists with indirect MRA, compared to 84 and 86 % with non-contrast MRI. This retrospective study shows that I-MRA is a highly accurate and sensitive method for the detection of labral tears. The data obtained supports the use of I-MRA as standard practice in patients with shoulder instability due to suspected labral pathology where further investigative imaging is indicated. (orig.)

  2. Nuclear magnetic resonance investigation of the heavy fermion system Ce2CoAl7Ge4

    Science.gov (United States)

    Dioguardi, A. P.; Guzman, P.; Rosa, P. F. S.; Ghimire, N. J.; Eley, S.; Brown, S. E.; Thompson, J. D.; Bauer, E. D.; Ronning, F.

    2017-12-01

    We present nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements performed on single crystalline Ce2CoAl7Ge4 , a member of a recently discovered family of heavy fermion materials Ce2M Al7Ge4 (M =Co , Ir, Ni, or Pd). Previous measurements indicated a strong Kondo interaction as well as magnetic order below TM=1.8 K . Our NMR spectral measurements show that the Knight shift K is proportional to the bulk magnetic susceptibility χ at high temperatures. A clear Knight shift anomaly (K ¬∝χ ) is observed at coherence temperatures T*˜17.5 K for H0∥c ̂ and 10 K for H0∥a ̂ at the 59Co site, and T*˜12.5 K at the 27Al(3) site for H0∥a ̂ characteristic of the heavy fermion nature of this compound. At high temperatures, the 59Co NMR spin-lattice relaxation rate T1-1 is dominated by spin fluctuations of the 4 f local moments with a weak metallic background. The spin fluctuations probed by 59Co NMR are anisotropic and larger in the basal plane than in the c direction. Furthermore, we find (T1T K ) -1∝T-1 /2 at the 59Co site as expected for a Kondo system for T >T* and T >TK . 59Co NQR T1-1 measurements at low temperatures indicate slowing down of spin fluctuations above the magnetic ordering temperature TM˜1.8 K . A weak ferromagnetic character of fluctuations around q =0 is evidenced by an increase of χ T versus T above the magnetic ordering temperature. We also find good agreement between the observed and calculated electric field gradients at all observed sites.

  3. Market applications of Resistivity, Induced Polarisation, Magnetic Resonance and Electromagnetic methods for Groundwater Investigations, Mining Exploration, Environmental and Engineering Surveys

    Science.gov (United States)

    Bernard, J.

    2012-12-01

    The Manufacturers of geophysical instruments have been facing these past decades the fast evolution of the electronics and of the computer sciences. More automatisms have been introduced into the equipment and into the processing and interpretation software which may let believe that conducting geophysical surveys requires less understanding of the method and less experience than in the past. Hence some misunderstandings in the skills that are needed to make the geophysical results well integrated among the global information which the applied geologist needs to acquire to be successful in his applications. Globally, the demand in geophysical investigation goes towards more penetration depth, requiring more powerful transmitters, and towards a better resolution, requiring more data such as in 3D analysis. Budgets aspects strongly suggest a high efficiency in the field associated to high speed data processing. The innovation is required in all aspects of geophysics to fit with the market needs, including new technological (instruments, software) and methodological (methods, procedures, arrays) developments. The structures in charge of the geophysical work can be public organisations (institutes, ministries, geological surveys,…) or can come from the private sector (large companies, sub-contractors, consultants, …), each one of them getting their own constraints in the field work and in the processing and interpretation phases. In the applications concerning Groundwater investigations, Mining Exploration, Environmental and Engineering surveys, examples of data and their interpretation presently carried out all around the world will be presented for DC Resistivity (Vertical Electrical Sounding, 2D, 3D Resistivity Imaging, Resistivity Monitoring), Induced Polarisation (Time Domain 2D, 3D arrays for mining and environmental), Magnetic Resonance Sounding (direct detection and characterisation of groundwater) and Electromagnetic (multi-component and multi

  4. Fourier transform nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Geick, R.

    1981-01-01

    This review starts with the basic principles of resonance phenomena in physical systems. Especially, the connection is shown between the properties of these systems and Fourier transforms. Next, we discuss the principles of nuclear magnetic resonance. Starting from the general properties of physical systems showing resonance phenomena and from the special properties of nuclear spin systems, the main part of this paper reviews pulse and Fourier methods in nuclear magnetic resonance. Among pulse methods, an introduction will be given to spin echoes, and, apart from the principle of Fourier transform nuclear magnetic resonance, an introduction to the technical problems of this method, e.g. resolution in the frequency domain, aliasing, phase and intensity errors, stationary state of the spin systems for repetitive measurements, proton decoupling, and application of Fourier methods to systems in a nonequilibrium state. The last section is devoted to special applications of Fourier methods and recent developments, e.g. measurement of relaxation times, solvent peak suppression, 'rapid scan'-method, methods for suppressing the effects of dipolar coupling in solids, two-dimensional Fourier transform nuclear magnetic resonance, and spin mapping or zeugmatography. (author)

  5. Magnetic resonance and porous materials

    International Nuclear Information System (INIS)

    McDonald, P.; Strange, J.

    1998-01-01

    Mention the words magnetic resonance to your medical advisor and he or she will immediately think of a multi-million pound scanner that peers deep into the brain. A chemist, on the other hand, will imagine a machine that costs several hundred thousand pounds and produces high-resolution spectra for chemical analysis. Food technologists will probably think of a bench-top instrument for determining moisture content, while an oil prospector will envisage a device that can be operated several kilometres down an oil well. To a physicist the term is more likely to conjure up a mental picture of nuclear spins precessing in a magnetic field. These examples illustrate the diverse aspects of a phenomenon discovered by physicists over 50 years ago. Electron spin resonance was first discovered by Russian scientists, and nuclear magnetic resonance was discovered in the US shortly afterwards by Ed Purcell at Harvard University and Felix Bloch at Stanford University. Today, nuclear magnetic resonance (NMR) is the most widely used technique. Modern NMR machines are making it possible to probe microstructure and molecular movement in materials as diverse as polymers, cements, rocks, soil and foods. NMR allows the distribution of different components in a material to be determined with a resolution approaching 1μm, although the signal can be sensitive to even smaller lengthscales. In this article the authors describe how physicists are still developing magnetic resonance to exploit a range of new applications. (UK)

  6. GHz nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Cross, T.A.; Drobny, G.; Trewhella, J.

    1994-12-01

    For the past dozen years, 500- and 600-MHz spectrometers have become available in many laboratories. The first 600-MHz NMR spectrometer (at Carnegie Mellon University) was commissioned more than 15 years ago and, until 1994, represented the highest field available for high-resolution NMR. This year, we have witnessed unprecedented progress in the development of very high field magnets for NMR spectroscopy, including the delivery of the first commercial 750-MHz NMR spectrometers. In addition, NMR signals have been obtained from 20-Tesla magnets (850 MHz for {sup 1}H`s) at both Los Alamos National Laboratory and Florida State University in the NHMFL (National High Magnetic Field Laboratory). These preliminary experiments have been performed in magnets with 100-ppm homogeneity, but a 20-Tesla magnet developed for the NHMFL will be brought to field this year with a projected homogeneity of 0.1 ppm over a 1-cm-diam spherical volume.

  7. Principles of magnetic resonance imaging

    International Nuclear Information System (INIS)

    Mlynarik, V.; Tkac, I.; Srbecky, M.

    1995-01-01

    The aim of this review is to describe and explain the basic principles of magnetic resonance imaging. The first part of the text is devoted to the phenomenon of magnetic resonance (the interaction of RF magnetic field with the set of magnetic moments in the homogeneous magnetic field) and to relaxation processes. Then, the creation of MR image is described (slice selection, phase and frequency encoding of spatial information). The basic and the most frequently used techniques are explained (spin echo, gradient echo). The way the repetition and echo times influence the image quality and contrast (T1 or T2 weighing) is described. The part with the technical description of the MR equipment is included in the review. The MR imagination examination are compared with X-ray computer tomography technique

  8. [An investigative report concerning safety and management in the magnetic resonance environment: there are more accidents than expected].

    Science.gov (United States)

    Doi, Tsukasa; Yamatani, Yuya; Ueyama, Tsuyoshi; Nishiki, Shigeo; Ogura, Akio; Kawamitsu, Hideaki; Tsuchihashi, Toshio; Okuaki, Tomoyuki; Matsuda, Tsuyoshi; Kumashiro, Masayuki

    2011-01-01

    Using a questionnaire, we surveyed 2,500 facilities in Japan to clarify medical accidents concerning the magnetic resonance device and its environment. Data derived from 1,319 valid responses (52.8%), allowed us to analyze the situation of (or the reason for) the occurrence of the accidents and their environmental factors. Five hundred and nine facilities (39% of all facilities) had the experience of magnetically induced displacement of the large ferromagnetic material. Intravenous (I.V.) drip stands were involved the largest number of them: 31% (228 cases). Oxygen bottles had the second largest number of incidents: 20%. There were also many incidents involving various materials brought in by non-medical staff (e.g. stepladder for construction). About 20% of the accidents occurred outside of working hours. Patients in 12% of the facilities (154 facilities) experienced burns. In 39 of the cases, burns were received to the inside of the thighs. In 38 of the cases, patients received burns from an electrical cable touching the skin. There were also frequent incidents of burning regarding the boa. We received reports of burns and pain from the halo vest even though it's required to be worn for MR safety. Regarding incidents of contraindications, 280 patients with pacemakers were brought into the magnetic resonance (MR) inspection room. Twelve percent of the facilities experienced natural quench. Lack of training for the staff who introduce and operate high magnetic field devices are considered involving frequently occurring accidents of attractions and burns at hospitals with over 500 beds caused by carrying in materials.

  9. Bifurcation magnetic resonance in films magnetized along hard magnetization axis

    Energy Technology Data Exchange (ETDEWEB)

    Vasilevskaya, Tatiana M., E-mail: t_vasilevs@mail.ru [Ulyanovsk State University, Leo Tolstoy 42, 432017 Ulyanovsk (Russian Federation); Sementsov, Dmitriy I.; Shutyi, Anatoliy M. [Ulyanovsk State University, Leo Tolstoy 42, 432017 Ulyanovsk (Russian Federation)

    2012-09-15

    We study low-frequency ferromagnetic resonance in a thin film magnetized along the hard magnetization axis performing an analysis of magnetization precession dynamics equations and numerical simulation. Two types of films are considered: polycrystalline uniaxial films and single-crystal films with cubic magnetic anisotropy. An additional (bifurcation) resonance initiated by the bistability, i.e. appearance of two closely spaced equilibrium magnetization states is registered. The modification of dynamic modes provoked by variation of the frequency, amplitude, and magnetic bias value of the ac field is studied. Both steady and chaotic magnetization precession modes are registered in the bifurcation resonance range. - Highlights: Black-Right-Pointing-Pointer An additional bifurcation resonance arises in a case of a thin film magnetized along HMA. Black-Right-Pointing-Pointer Bifurcation resonance occurs due to the presence of two closely spaced equilibrium magnetization states. Black-Right-Pointing-Pointer Both regular and chaotic precession modes are realized within bifurcation resonance range. Black-Right-Pointing-Pointer Appearance of dynamic bistability is typical for bifurcation resonance.

  10. Bifurcation magnetic resonance in films magnetized along hard magnetization axis

    International Nuclear Information System (INIS)

    Vasilevskaya, Tatiana M.; Sementsov, Dmitriy I.; Shutyi, Anatoliy M.

    2012-01-01

    We study low-frequency ferromagnetic resonance in a thin film magnetized along the hard magnetization axis performing an analysis of magnetization precession dynamics equations and numerical simulation. Two types of films are considered: polycrystalline uniaxial films and single-crystal films with cubic magnetic anisotropy. An additional (bifurcation) resonance initiated by the bistability, i.e. appearance of two closely spaced equilibrium magnetization states is registered. The modification of dynamic modes provoked by variation of the frequency, amplitude, and magnetic bias value of the ac field is studied. Both steady and chaotic magnetization precession modes are registered in the bifurcation resonance range. - Highlights: ► An additional bifurcation resonance arises in a case of a thin film magnetized along HMA. ► Bifurcation resonance occurs due to the presence of two closely spaced equilibrium magnetization states. ► Both regular and chaotic precession modes are realized within bifurcation resonance range. ► Appearance of dynamic bistability is typical for bifurcation resonance.

  11. Recommendations concerning magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    1986-01-01

    In medicine the technique of nuclear magnetic resonance (NMR) is applied in the form of in vivo nuclear magnetic resonance spectroscopy (MRS). In vivo MRS can be carried out non-invasively. The committee of the Dutch Health Council briefly discusses the qualities and potentialities of the nuclei that will probably be used in future clinical spectroscopy: 31 P, 13 C, 1 H (and possibly 19 F and 23 Na). The committee discusses several possibilities of combining imaging and spectroscopy. The imaging of nuclei other than protons is also possible with MRS. Potential applications are considered in oncology, cardiology, neurology and hepatology. (Auth.)

  12. Migraine and magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Younis, Samaira; Hougaard, Anders; Vestergaard, Mark B.

    2017-01-01

    Purpose of review: To present an updated and streamlined overview of the metabolic and biochemical aspect of the migraine pathophysiology based on findings from phosphorous (31P) and hydrogen (1H) magnetic resonance spectroscopy (MRS) studies. Recent findings: Despite of the variation in the meth......Purpose of review: To present an updated and streamlined overview of the metabolic and biochemical aspect of the migraine pathophysiology based on findings from phosphorous (31P) and hydrogen (1H) magnetic resonance spectroscopy (MRS) studies. Recent findings: Despite of the variation...

  13. Investigation into the quantitative and qualitative characteristics of choroidal melanoma through magnetic resonance imaging and B-scan ultrasound

    Directory of Open Access Journals (Sweden)

    Papayiannis V

    2017-08-01

    Full Text Available Vassilis Papayiannis,1 Konstantinos T Tsaousis,2,3 Constantinos A Kouskouras,4 Afroditi Haritanti,4 Vasilios F Diakonis,5 Ioannis T Tsinopoulos2 1Department of Radiology, Papageorgiou General Hospital, 2Department of Ophthalmology, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3John A Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 4Department of Radiology, AHEPA Aristotle University Hospital of Thessaloniki, Thessaloniki, Greece; 5Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami, Miami, FL, USA Objective: To investigate the homogeneity and vascularity of choroidal melanoma through magnetic resonance imaging (MRI and brightness modulation (B-mode ultrasound scan and their correlation with dimensions of tumor, as well as to measure the sensitivity of both modalities in retinal detachment (RD detection.Materials and methods: This retrospective chart review included patients diagnosed with choroidal melanoma. All these patients underwent MRI scans using T2-weighted (T2-WI and T1-weighted (T1-WI sequences, before and after an intravenous injection of paramagnetic contrast material. The patients were also examined using a B-mode ultrasound scan, and the results from both modalities were compared (tumor homogeneity, tumor height, tumor base diameter, and tumor vascularity.Results: Forty-two patients (mean age =65.33±12.51 years with choroidal melanoma were included in the study. Homogeneity was confirmed in 16 patients through ultrasound scan, in 19 patients through T1-WI sequence, in 21 patients through T2-WI sequence, and in 25 patients through T1-WI sequence + contrast (gadolinium. Patients with homogenous tumors presented with lower (P=0.0045 mean height than that of those with nonhomogenous tumors, whereas no statistically significant difference was found for base diameter measurements (P=0.056. Patients with tumors of high vascularity presented with greater mean height (P=0.000638 and

  14. Investigation into the quantitative and qualitative characteristics of choroidal melanoma through magnetic resonance imaging and B-scan ultrasound.

    Science.gov (United States)

    Papayiannis, Vassilis; Tsaousis, Konstantinos T; Kouskouras, Constantinos A; Haritanti, Afroditi; Diakonis, Vasilios F; Tsinopoulos, Ioannis T

    2017-01-01

    To investigate the homogeneity and vascularity of choroidal melanoma through magnetic resonance imaging (MRI) and brightness modulation (B-mode) ultrasound scan and their correlation with dimensions of tumor, as well as to measure the sensitivity of both modalities in retinal detachment (RD) detection. This retrospective chart review included patients diagnosed with choroidal melanoma. All these patients underwent MRI scans using T2-weighted (T2-WI) and T1-weighted (T1-WI) sequences, before and after an intravenous injection of paramagnetic contrast material. The patients were also examined using a B-mode ultrasound scan, and the results from both modalities were compared (tumor homogeneity, tumor height, tumor base diameter, and tumor vascularity). Forty-two patients (mean age=65.33±12.51 years) with choroidal melanoma were included in the study. Homogeneity was confirmed in 16 patients through ultrasound scan, in 19 patients through T1-WI sequence, in 21 patients through T2-WI sequence, and in 25 patients through T1-WI sequence + contrast (gadolinium). Patients with homogenous tumors presented with lower ( P =0.0045) mean height than that of those with nonhomogenous tumors, whereas no statistically significant difference was found for base diameter measurements ( P =0.056). Patients with tumors of high vascularity presented with greater mean height ( P =0.000638) and greater mean base diameter compared with those with tumors of low vascularity ( P =0.019543). RD was detected in 26 patients through T1-WI sequence, in 13 patients through T2-WI sequence, in 26 patients through T1-WI sequence + contrast, and in 32 patients through ultrasound scan, which proved to be the most sensitive modality. The height of choroidal melanoma was positively correlated with tumor's homogeneity. Melanomas of greater height were found to be less homogenous, due to increased degeneration and higher occurrence of intratumoral hemorrhage. In addition, choroidal melanoma's height was also

  15. Investigation of Resonance Effect Caused by Local Exposure of Extremely Low Frequency Magnetic Field on Brain Signals: A Randomize Clinical Trial

    Directory of Open Access Journals (Sweden)

    Rasul Zadeh Tabataba’ei K

    2011-03-01

    Full Text Available Background and Objectives: Some studies have investigated the effects of extremely low frequency magnetic fields (ELF-MFs on brain signals, but only few of them have reported that humans exposed to magnetic fields exhibit changes in brain signals at the frequency of stimulation, i.e. resonance effect. In most investigations, researchers usually take advantage of a uniform field which encompasses the head. The aim of present study was to expose different parts of the brain to ELF-MFs locally and to investigate variation of brain signal and resonance effect.Methods: The subjects consisting of 19 male-students with the mean age of 25.6±1.6 years participated in this study. Local ELF-MFs with 3, 5, 10, 17 and 45Hz frequencies and 240 μT intensity was applied on five points (T3, T4, Cz, F3 and F4 of participants scalp Separately in 10-20 system. In the end, relative power over this points in common frequency bands and at the frequency of magnetic fields was evaluated by paired t-test.Results: Exposure of Central area by local magnetic field caused significant change (p<0.05 in the forehead alpha band. Reduction in the alpha band over central area was observed when temporal area was exposed to ELF MF.Conclusion: The results showed that resonance effect in the brain signals caused by local magnetic field exposure was not observed and change in every part of the relative power spectrum might occur. The changes in the EEG bands were not limited necessarily to the exposure point.

  16. Magnetic resonance imaging of hypophysis

    International Nuclear Information System (INIS)

    Malla Huesh, I. V.

    2016-01-01

    nuclei and sulci. FLAIR - sequences with its advantage in suppressing the signal from the cerebrospinal fluid is useful in case of meningeal involvement in hypophysitis. DWI is essential in case of ischemia, apoplexy and associated necrotic changes. Contrast medium application is not compulsory, but it increases the sensitivity of the method, especially in young patients. The contrast used is Gadolinium, applied according to the body weight. After contrast application the gland enhances homogeneously. MR-methods made are responsible for throwing light upon the normal images of the pituitary gland from the neonatal patients to adults, explaining the malformative and rare conditions, leading to disturbances in the hypothalamic-pituitary axis. The most common reason for pathologic conditions in the hypothalamic-pituitary axis remain the adenomas. MR-imaging is the method of choice to rule out a suspected formation in the sellar area. Small adenomas with size around 3mm are now detectable with the use of equipment with high strength of magnetic field. Authors agree on the fact the secreting and nonsecreting adenomas need a thorough MR-follow up in time, especially the nonsecreting ones that are usually detected accidentally. In the era before the multislice diagnostic imaging the pathologies in the hypothalamic-pituitary axis were difficult to assess. The introduction of the new methods of investigation made the diagnosis of such conditions achievable. Magnetic resonance imaging is convenient, informative and clinically applicable for detecting hypothalamic-pituitary axis. However there is no agreement how the MR-protocol should be carried out. MR with high magnetic field is an essential tool in obtaining images with better quality, higher diagnostic value and the opportunity for performing sequences in thin slices and reconstructions in different planes. Key words: Magnetic Resonance Imaging. Hypophysis. 3TESLA

  17. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance ...

  18. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - ...

  19. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... Magnetic Resonance Imaging Sponsored by Please note RadiologyInfo.org is not a medical facility. Please contact your ... links: For the convenience of our users, RadiologyInfo .org provides links to relevant websites. RadiologyInfo.org , ACR ...

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. MRI ...

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. MRI ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... structures of the brain and can also provide functional information (fMRI) in selected cases. MR images of ... Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain ...

  3. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... of which shows a thin slice of the body. The images can then be studied from different angles by ... about radiology? Share your patient story here Images ... Articles and Media Catheter Angiography Magnetic Resonance, Functional (fMRI) - Brain Children's ( ...

  4. Muscle fat content and abdominal adipose tissue distribution investigated by magnetic resonance spectroscopy and imaging in obese children and youths

    Directory of Open Access Journals (Sweden)

    Cilius E. Fonvig

    2012-01-01

    Full Text Available The degree of fat deposition in muscle and its implications for obesity-related complications in youth are not well understood. One hundred and fifty-nine patients (mean age: 13.3 years; range: 6-20 with a body mass index (BMI >90th percentile for age and sex were included. Muscle fat content (MFC was measured in the psoas muscle by proton magnetic resonance spectroscopy. The patients were assigned to two groups: MFC <5% or ³5%. Visceral adipose tissue volume (VAT and subcutaneous adipose tissue volume (SAT were measured by magnetic resonance imaging. Blood samples were obtained from 119 patients, and liver enzyme concentrations and other variables were measured. The data were analysed to detect any associations between MFC and BMI standard deviation scores, VAT and SAT, blood values, and physical activity levels. The mean BMI standard deviation score (SDS was 3.04 (range 1.32-5.02. The mean MFC was 8.9% (range 0.8-46.7, and 118 (74.2% of 159 patients had an MFC ³5%. Children with a high MFC had a higher BMI SDS (P=0.03 and had a higher VAT, but not SAT or SAT/VAT ratio. Both intramyocellular lipid (IMCL and extramyocellular lipid (EMCL content were elevated in patients with an MFC ³5%. Blood values and physical activity levels did not differ between the two groups. Severely obese children and adolescents tend to have a high MFC, which is associated with elevated VAT and IMCL and EMCL content. An increased MFC may be associated with impaired metabolic processes, which may predispose young people to obesity-related complications.

  5. Magnetic resonance imaging of semicircular canals.

    Science.gov (United States)

    Sbarbati, A; Leclercq, F; Zancanaro, C; Antonakis, K

    1992-01-01

    The present paper reports the results of the first investigation of the semicircular canals in a living, small animal by means of high spatial resolution magnetic resonance imaging. This procedure is noninvasive and allows identification of the endolymphatic and perilymphatic spaces yielding a morphology quite consistent with direct anatomical examination. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:1506290

  6. Magnetic Resonance Imaging (MRI): Brain (For Parents)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Magnetic Resonance Imaging (MRI): Brain KidsHealth / For Parents / Magnetic Resonance Imaging (MRI): Brain What's in this article? What ...

  7. Advances in magnetic and optical resonance

    CERN Document Server

    Warren, Warren S

    1997-01-01

    Since 1965, Advances in Magnetic and Optical Resonance has provided researchers with timely expositions of fundamental new developments in the theory of, experimentation with, and application of magnetic and optical resonance.

  8. Magnetic resonance for wireless power transfer

    OpenAIRE

    Hui, SYR

    2016-01-01

    Magnetic resonance has been a cornerstone of nonradiative wireless power transfer (WPT) since the late 19th century. However, some researchers have the misconception that magnetic resonance for WPT was developed recently. This article traces some early work of Tesla and other researchers related to the use of magnetic resonance in WPT. Included are some examples of magnetic resonance-based WPT projects conducted by researchers in the biomedical and power electronics communities over the last ...

  9. A proton nuclear magnetic resonance investigation of proximal histidyl residues in human normal and abnormal hemoglobins: a probe for the heme pocket

    International Nuclear Information System (INIS)

    Takahashi, S.; Lin, A.K.L.; Ho, C.

    1982-01-01

    Proton nuclear magnetic resonance spectroscopy at 250 MHz has been used to investigate the conformations of proximal histidyl residues of human normal adult hemoglobin, hemoglobin Kempsey [K145(HC2) Tyr #betta# Asp], and hemoglobin McKees Rocks [K145(HC2) Tyr #betta# Term] around neutral pH in H 2 O at 27 0 C, all in the deoxy form. Two resonances that occur between 58 and 76 ppm downfield from the water proton signal have been assigned to the hyperfine shifted proximal histidyl NH-exchangeable protons of the J and K-chains of deoxyhemoglobin. These two resonances are sensitive to the quaternary state of hemoglobin, amino acid substitutions in the J 1 K 2 -subunit interface and in the carboxy-terminal region of the K-chain, and the addition of organic phosphates. The experimental results show that there are differences in the heme pockets among these four hemoglobins studied. The structural and dynamic information derived from the hyperfine shifted proximal histidyl NH-exchangeable proton resonances complement that obtained from the ferrous hyperfine shifted and exchangeable proton resonances of deoxyhemoglobin over the spectral region from 5 to 20 ppm downfield from H 2 O. The relationship between these findings and Perutz's stereochemical mechanism for the cooperative oxygenation of hemoglobin is discussed

  10. Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging.

    Directory of Open Access Journals (Sweden)

    Clare E McElcheran

    Full Text Available Deep Brain Stimulation (DBS is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF transmission field during imaging. In the present work, parallel RF transmission (pTx is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing p

  11. Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging.

    Science.gov (United States)

    McElcheran, Clare E; Yang, Benson; Anderson, Kevan J T; Golenstani-Rad, Laleh; Graham, Simon J

    2015-01-01

    Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS

  12. Nonlinear nuclear magnetic resonance in ferromagnets

    International Nuclear Information System (INIS)

    Nurgaliev, T.

    1988-01-01

    The properties of nonlinear nuclear magnetic resonance (NMR) have been studied theoretically by taking into account the interaction between NMR and FMR in the ferromagnets. The Landau-Lifshitz-Bloch equations, describing the electron and nuclear magnetization behaviour in ferromagnets are presented in an integral form for a weakly excited electronic system. The stationary solution of these equations has been analysed in the case of equal NMR and FMR frequencies: the criteria for the appearance of two stable dynamic states is found and the high-frequency magnetic susceptibility for these systems is investigated. 2 figs., 8 refs

  13. Nuclear magnetic resonance method and apparatus

    International Nuclear Information System (INIS)

    Young, I.R.

    1983-01-01

    In a method of investigating the distribution of a quantity in a chosen region of a body (E) by nuclear magnetic resonance techniques movement of the body during the investigation is monitored by probes (A, B C) (C extends orthogonally to A and B) attached to the body and responsive to magnetic fields applied to the body during the investigation. An apparatus for carrying out the method is also described. If movement is detected, due compensation may be made during processing of the collected data, or the latter may be re-ascertained after appropriate adjustment e.g. a change in the RF excitation frequency. (author)

  14. Magnetic resonance tomography in syringomyelia

    International Nuclear Information System (INIS)

    Koehler, D.; Treisch, J.; Hertel, G.; Schoerner, W.; Fiegler, W.; Staedtisches Rudolf-Virchow Krankenhaus, Berlin

    1985-01-01

    Thirteen patients with a clinical diagnosis of syringomyelia were examined by nuclear tomography (0.35 T magnet) in the spin-echo mode. In all thirteen patients, the T1 images (Se 400/35) showed a longitudinal cavity with a signal intensity of CSF. The shape and extent of the syrinx could be adequately demonstrated in 12 of the 13 examinations. Downward displacement of the cerebellar tonsils was seen in eight cases. The examination took between half and one hour. Advantages of magnetic resonance tomography (nuclear tomography) include the absence of artifacts, images in the line of the lesion and its non-invasiveness. (orig.) [de

  15. Limits to magnetic resonance microscopy

    International Nuclear Information System (INIS)

    Glover, Paul; Mansfield, Peter

    2002-01-01

    The last quarter of the twentieth century saw the development of magnetic resonance imaging (MRI) grow from a laboratory demonstration to a multi-billion dollar worldwide industry. There is a clinical body scanner in almost every hospital of the developed nations. The field of magnetic resonance microscopy (MRM), after mostly being abandoned by researchers in the first decade of MRI, has become an established branch of the science. This paper reviews the development of MRM over the last decade with an emphasis on the current state of the art. The fundamental principles of imaging and signal detection are examined to determine the physical principles which limit the available resolution. The limits are discussed with reference to liquid, solid and gas phase microscopy. In each area, the novel approaches employed by researchers to push back the limits of resolution are discussed. Although the limits to resolution are well known, the developments and applications of MRM have not reached their limit. (author)

  16. Magnetic resonance and its applications

    CERN Document Server

    Chizhik, Vladimir I; Donets, Alexey V; Frolov, Vyacheslav V; Komolkin, Andrei V; Shelyapina, Marina G

    2014-01-01

    The book provides a basic understanding of the underlying theory, fundamentals and applications of magnetic resonance The book implies a few levels of the consideration (from simple to complex) of phenomena, that can be useful for different groups of readers The introductory chapter provides the necessary underpinning knowledge for newcomers to the methods The exposition of theoretical materials goes from initial to final formulas through detailed intermediate expressions.

  17. Experimental models of brain ischemia: a review of techniques, magnetic resonance imaging and investigational cell-based therapies

    Directory of Open Access Journals (Sweden)

    Alessandra eCanazza

    2014-02-01

    Full Text Available Stroke continues to be a significant cause of death and disability worldwide. Although major advances have been made in the past decades in prevention, treatment and rehabilitation, enormous challenges remain in the way of translating new therapeutic approaches from bench to bedside. Thrombolysis, while routinely used for ischemic stroke, is only a viable option within a narrow time window. Recently, progress in stem cell biology has opened up avenues to therapeutic strategies aimed at supporting and replacing neural cells in infarcted areas. Realistic experimental animal models are crucial to understand the mechanisms of neuronal survival following ischemic brain injury and to develop therapeutic interventions. Current studies on experimental stroke therapies evaluate the efficiency of neuroprotective agents and cell-based approaches using primarily rodent models of permanent or transient focal cerebral ischemia. In parallel, advancements in imaging techniques permit better mapping of the spatial-temporal evolution of the lesioned cortex and its functional responses. This review provides a condensed conceptual review of the state of the art of this field, from models and magnetic resonance imaging techniques through to stem cell therapies.

  18. Deep and superficial infrapatellar bursae: cadaveric investigation of regional anatomy using magnetic resonance after ultrasound-guided bursography

    Energy Technology Data Exchange (ETDEWEB)

    Viegas, Flavio C.; Trudell, Debbie J.; Haghighi, Parviz; Resnick, Donald [Veterans Affairs Medical Center - San Diego, San Diego, CA (United States); Aguiar, Rodrigo O.C. [Veterans Affairs Medical Center - San Diego, San Diego, CA (United States); Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ (Brazil); Gasparetto, Emerson; Marchiori, Edson [Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ (Brazil)

    2007-01-15

    To demonstrate the anatomy of the deep and superficial infrapatellar bursae using magnetic resonance (MR) imaging and anatomic correlation in cadavers. MR imaging of the infrapatellar bursae of nine cadaveric knees was performed after ultrasound-guided bursography. The images were compared with those seen on anatomic sectioning. Histologic analysis was obtained in two specimens. The deep infrapatellar bursa (DIB) was visualized in all specimens (n=9) and the superficial infrapatellar bursa (SIB) in five specimens (55%). The mean dimensions of the DIB in the craniocaudal, mediolateral, and anteroposterior planes were respectively 25, 28.7, and 6 mm, and for SIB 19.5, 21.2 and 2.2 mm. A fat apron dividing the DIB was depicted in eight knees (89%). Lateral extension of the DIB beyond the patellar tendon was observed in 100% of cases. Cadaveric analysis depicted a thin septum in the SIB in four of five cases (80%). The DIB is generally present and extends beyond the lateral margin of the patellar tendon. A fat apron partially separating this structure is usual. The SIB is not an unusual finding and may have a septum separating its compartments. (orig.)

  19. A methodology to investigate the impact of image distortions on the radiation dose when using magnetic resonance images for planning

    Science.gov (United States)

    Yan, Yue; Yang, Jinzhong; Beddar, Sam; Ibbott, Geoffrey; Wen, Zhifei; Court, Laurence E.; Hwang, Ken-Pin; Kadbi, Mo; Krishnan, Sunil; Fuller, Clifton D.; Frank, Steven J.; Yang, James; Balter, Peter; Kudchadker, Rajat J.; Wang, Jihong

    2018-04-01

    We developed a novel technique to study the impact of geometric distortion of magnetic resonance imaging (MRI) on intensity-modulated radiation therapy treatment planning. The measured 3D datasets of residual geometric distortion (a 1.5 T MRI component of an MRI linear accelerator system) was fitted with a second-order polynomial model to map the spatial dependence of geometric distortions. Then the geometric distortion model was applied to computed tomography (CT) image and structure data to simulate the distortion of MRI data and structures. Fourteen CT-based treatment plans were selected from patients treated for gastrointestinal, genitourinary, thoracic, head and neck, or spinal tumors. Plans based on the distorted CT and structure data were generated (as the distorted plans). Dose deviations of the distorted plans were calculated and compared with the original plans to study the dosimetric impact of MRI distortion. The MRI geometric distortion led to notable dose deviations in five of the 14 patients, causing loss of target coverage of up to 3.68% and dose deviations to organs at risk in three patients, increasing the mean dose to the chest wall by up to 6.19 Gy in a gastrointestinal patient, and increases the maximum dose to the lung by 5.17 Gy in a thoracic patient.

  20. Magnetic resonance imaging

    International Nuclear Information System (INIS)

    Beer, A.; Bielke, G.; Bockenheimer, S.; Brenner, G.; Dieringer, H.; Esswein, H.; Hopf, H.; Koch, H.; Meves, M.; Nagel, F.; Oberstein, A.; Ostheimer, E.; Pfaff, M.; Schlaps, D.; Schopka, H.J.; Seiderer, M.

    1990-01-01

    The study investigates three points of main interest: (1) The clinical efficacy of MR imaging as a routine method, if possible to be assessed in comparison to comparable imaging methods, and referring to a broad spectrum of available types of equipment and modes of operation, to be expressed in terms of diagnostic value and indication of therapy. (2) Specific economic aspects, considering different sites of operation and application conditions. (3) Results of clinical application with regard to individual cases (patient careers), in order to establish a nationwide basis for economic cost-benefit assessment of this diagnostic tool. Another aspect taken into account whenever available data allow so, is substitutional or additional application of MR imaging. The survey is performed on the basis of data accumulated by more than 21.000 MR examinations, and of data describing the application environment, furnished by 25 users from university hospitals, general hospitals, or private practice. (orig./HP) [de

  1. Magnetic resonance imaging in sudden deafness

    International Nuclear Information System (INIS)

    Ramos, Hugo Valter Lisboa; Barros, Flavia Alencar; Penido, Norma de Oliveira; Souza, Ana Claudia Valerio de; Yamaoka, Wellington Yugo; Yamashita, Helio

    2005-01-01

    The etiology of sudden deafness can remain undetermined despite extensive investigation. This study addresses the value of magnetic resonance imaging in the analysis of sudden deafness patients.Study Design: transversal cohort.Material And Method: In a prospective study, 49 patients attended at otolaryngology emergency room of Federal University of Sao Paulo - Escola Paulista de Medicina, from April 2001 to May 2003, were submitted to magnetic resonance imaging.Results: Magnetic Resonance abnormalities were seen in 23 (46.9%) patients and revealed two tumors suggestive of meningioma, three vestibular schwannomas, thirteen microangiopathic changes of the brain and five (21.7%) pathological conditions of the labyrinth.Conclusion: Sudden deafness should be approached as a symptom common to different diseases. The presence of cerebellopontine angle tumors in 10.2% of our cases, among other treatable causes, justifies the recommendation of gadolinium-enhanced magnetic resonance use, not only to study the auditory peripheral pathway, but to study the whole auditory pathway including the brain. (author)

  2. Magnetic resonance: safety measures and biological effects

    International Nuclear Information System (INIS)

    Gordillo, I.; Lafuente, J.; Fernandez, C.; Barbero, M.J.; Cascon, E.

    1997-01-01

    The biological effects of electromagnetic fields is currently a subject of great controversy. For this reason, magnetic resonance imaging (MRI) and spectroscopy are constantly under investigation. The source of the risk in MRI is associated with the three types of electromagnetic radiation to which the patient is exposed: the static magnetic field, variable (gradient) magnetic fields and radiofrequency fields. Each is capable of producing significant biological effects when employed at sufficient intensity. Patients exposed to risk sources are those situated within the lines of force of the magnetic field, ellipsoid lines that are arranged around the magnet, representing the strength of the surrounding field. To date, at the intensity normally utilized in MRI(<2T) and respecting the field limit recommendations established by the US Food and Drug Administration (FDA) for clinical use of this technique no adverse secondary biological effects have been reported. The known biological effects and other possible secondary effects are reviewed, and the recommended safety measures are discussed. (Author)

  3. Identifying Vulnerable Atherosclerotic Plaque in Rabbits Using DMSA-USPIO Enhanced Magnetic Resonance Imaging to Investigate the Effect of Atorvastatin.

    Directory of Open Access Journals (Sweden)

    Chunmei Qi

    Full Text Available Rupture of an atherosclerotic plaque is the primary cause of acute cardiovascular and cerebrovascular syndromes. Early and non-invasive detection of vulnerable atherosclerotic plaques (VP would be significant in preventing some aspects of these syndromes. As a new contrast agent, dimercaptosuccinic acid (DMSA modified ultra-small super paramagnetic iron oxide (USPIO was synthesized and used to identify VP and rupture plaque by magnetic resonance imaging (MRI.Atherosclerosis was induced in male New Zealand White rabbits by feeding a high cholesterol diet (n = 30. Group A with atherosclerosis plaque (n = 10 were controls. VP was established in groups B (n = 10 and C (n = 10 using balloon-induced endothelial injury of the abdominal aorta. Adenovirus-carrying p53 genes were injected into the aortic segments rich in plaques after 8 weeks. Group C was treated with atorvastatin for 8 weeks. Sixteen weeks later, all rabbits underwent pharmacological triggering, and imaging were taken daily for 5 d after DMSA-USPIO infusion. At the first day and before being killed, serum MMP-9, sCD40L, and other lipid indicators were measured.DMSA-USPIO particles accumulated in VP and rupture plaques. Rupture plaques appeared as areas of hyper-intensity on DMSA-USPIO enhanced MRI, especially T2*-weighted sequences, with a signal strength peaking at 96 h. The group given atorvastatin showed few DMSA-USPIO particles and had lower levels of serum indicators. MMP-9 and sCD40L levels in group B were significantly higher than in the other 2 groups (P <0.05.After successfully establishing a VP model in rabbits, DMSA-USPIO was used to enhance MRI for clear identification of plaque inflammation and rupture. Rupture plaques were detectable in this way probably due to an activating inflammatory process. Atorvastatin reduced the inflammatory response and stabilizing VP possibly by decreasing MMP-9 and sCD40L levels.

  4. Application of the laser induced fluorescence to the investigation of highly magnetized plasmas, heated by ion cyclotron resonance

    International Nuclear Information System (INIS)

    Pailloux, A.

    1997-01-01

    This work has been achieved in the frame of isotopic separation studies by in cyclotron resonance. For this purpose, in a highly magnetized (2 to 3 Tesla) and non-collisional (10 12 ions/cm 3 ) plasma, composed of metallic ions, a wave near the ion cyclotron frequency is thrown in order to heat selectively a given species. A laser induced fluorescence (LIP) has been developed on barium and gadolinium plasmas. The Larmor gyration of ions greatly modifies the interaction, which has been modelled through the time-dependent Schroedinger equation. The obtained excitation probably has been integrated over all the ions excited in the measurement volume in order to check that the LIF still leads to the distribution function of ion velocities. The influence of the Larmor motion of ions on the spectral distribution of LIF has been derived both theoretically and experimentally. The LIF diagnostics has been achieved with a dye O'ring laser. The barium ion has been excited on the transition 6142 angstrom, using rhodamine 6G dye, and the gadolinium ion on the pseudo-triplet 3861 angstrom, using exalite dye. Data treatment has been developed taking into account the Zeeman effect and the different heating of isotopes. The ionic temperature (from 1 eV to some hundreds eV) has been measured as a function of radiofrequency heating. Our experimental results are in good agreement with the selective heating theory. Also, the ion velocity distribution function has been found locally Maxwellian. And the behaviour of the plasma has been studied as a function of control parameters of the plasma source. (author)

  5. Identifying Vulnerable Atherosclerotic Plaque in Rabbits Using DMSA-USPIO Enhanced Magnetic Resonance Imaging to Investigate the Effect of Atorvastatin

    Science.gov (United States)

    Li, Dongye; Wu, Weiheng; Gong, Lei; Li, Yong; Zhang, Qingdui; Zhang, Tao; Zhang, Chao; Zhang, Yu

    2015-01-01

    Background Rupture of an atherosclerotic plaque is the primary cause of acute cardiovascular and cerebrovascular syndromes. Early and non-invasive detection of vulnerable atherosclerotic plaques (VP) would be significant in preventing some aspects of these syndromes. As a new contrast agent, dimercaptosuccinic acid (DMSA) modified ultra-small super paramagnetic iron oxide (USPIO) was synthesized and used to identify VP and rupture plaque by magnetic resonance imaging (MRI). Methods Atherosclerosis was induced in male New Zealand White rabbits by feeding a high cholesterol diet (n = 30). Group A with atherosclerosis plaque (n = 10) were controls. VP was established in groups B (n = 10) and C (n = 10) using balloon-induced endothelial injury of the abdominal aorta. Adenovirus-carrying p53 genes were injected into the aortic segments rich in plaques after 8 weeks. Group C was treated with atorvastatin for 8 weeks. Sixteen weeks later, all rabbits underwent pharmacological triggering, and imaging were taken daily for 5 d after DMSA-USPIO infusion. At the first day and before being killed, serum MMP-9, sCD40L, and other lipid indicators were measured. Results DMSA-USPIO particles accumulated in VP and rupture plaques. Rupture plaques appeared as areas of hyper-intensity on DMSA-USPIO enhanced MRI, especially T2*-weighted sequences, with a signal strength peaking at 96 h. The group given atorvastatin showed few DMSA-USPIO particles and had lower levels of serum indicators. MMP-9 and sCD40L levels in group B were significantly higher than in the other 2 groups (P MRI for clear identification of plaque inflammation and rupture. Rupture plaques were detectable in this way probably due to an activating inflammatory process. Atorvastatin reduced the inflammatory response and stabilizing VP possibly by decreasing MMP-9 and sCD40L levels. PMID:25973795

  6. Resonances and dipole moments in dielectric, magnetic, and magnetodielectric cylinders

    DEFF Research Database (Denmark)

    Dirksen, A.; Arslanagic, Samel; Breinbjerg, Olav

    2011-01-01

    An eigenfunction solution to the problem of plane wave scattering by dielectric, magnetic, and magnetodielectric cylinders is used for a systematic investigation of their resonances. An overview of the resonances with electric and magnetic dipole moments, needed in, e.g., the synthesis...

  7. X-ray resonant magnetic scattering investigations of hexagonal multiferroics RMnO3 (R = Dy, Ho, Er)

    International Nuclear Information System (INIS)

    Nandi, Shibabrata

    2009-01-01

    Electricity and magnetism were unified into a common subject by James Clerk Maxwell in the nineteenth century yielding the electromagnetic theory. Four equations govern the dynamics of electric charges and magnetic fields, commonly known as Maxwell's equations. Maxwell's equations demonstrate that an accelerated charged particle can produce magnetic fields and a time varying magnetic field can induce a voltage - thereby linking the two phenomena. However, in solids, electric and magnetic ordering are most often considered separately and usually with good reason: the electric charges of electrons and ions are responsible for the charge effects, whereas the electron spin governs magnetic properties.

  8. Investigation of suspected Guillain-Barre syndrome in childhood: what is the role for gadolinium enhanced magnetic resonance imaging of the spine?

    Science.gov (United States)

    Smith, Nicholas; Pereira, John; Grattan-Smith, Padraic

    2014-10-01

    To review the role of gadolinium-enhanced magnetic resonance imaging of the spine in the diagnosis of paediatric Guillain-Barre syndrome and compare it with nerve conduction studies and cerebrospinal fluid analysis. A retrospective review of investigations undertaken in children admitted to our institution with acute Guillain-Barre syndrome over a 10-year period was performed. Seven of eight children (88%) displayed post-gadolinium nerve root enhancement consistent with Guillain-Barre syndrome. This compared with supportive nerve conduction studies in 21/24 children (88%) and cerebrospinal fluid protein analysis consistent with the diagnosis in 16/20 children (80%). Nerve conduction studies are the recognised 'gold standard' technique for confirming a clinical diagnosis of Guillain-Barre syndrome. In this study, a high positive rate was demonstrated. While more experience is necessary, this study and the literature support gadolinium enhanced magnetic resonance imaging of the spine as a valuable, although not necessarily superior, investigation in the diagnosis of Guillain-Barre syndrome. It may be of particular benefit when specialist neurophysiology expertise is unavailable. © 2010 The Authors. Journal compilation © 2010 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

  9. Nuclear magnetic resonance - from molecules to man

    OpenAIRE

    Wüthrich, Kurt

    2017-01-01

    Initial observations of the physical phenomenon of nuclear magnetic resonance (NMR) date back to the late 1940s. In the following two decades high-resolution NMR in solution became an indispensible analytical tool in chemistry, and solid state NMR had an increasingly important role in physics. Some of the potentialities of the method for investigations of complex biological systems had also long been anticipated, and initial experiments with biological specimens were described already 30 year...

  10. The nuclear magnetic resonance well logging

    International Nuclear Information System (INIS)

    Zhang Yumin; Shen Huitang

    2003-01-01

    In this paper, the characteristic of the nuclear magnetic resonance logging is described at first. Then its development and its principle is presented. Compared with the nuclear magnetic resonance spectrometer, the magnet techniques is the first question that we must solve in the manufacture of the NMR well logging

  11. Nuclear magnetic resonance (NMR): principles and applications

    International Nuclear Information System (INIS)

    Quibilan, E.I.

    The basis for the phenomenon of nuclear magnetic resonance (NMR) is the ability of certain nuclei possessing both intrinsic angular momentum or ''spin'' I and magnetic moment to absorb electromagnetic energy in the radio frequency range. In principle, there are approximately 200 nuclei which may be investigated using the NMR technique. The NMR spectrum consists of intensity peaks along an axis calibrated in terms of the steady magnetic field or the frequency of the radiofrequency electromagnetic radiation. Analysis of the number, spacing, position and intensity of the lines in an NMR spectrum consists of intensity peaks along an axis calibrated in terms of the steady magnetic field or the frequency of the radiofrequency electromagnetic radiation. Analysis of the number, spacing, position and intensity of the lines in an NMR spectrum provides a variety of qualitative and quantitative analytical applications. The most obvious applications consist of the measurements of nuclear properties, such as spin number and nuclear magnetic moment. In liquids, the fine structure of resonance spectra provides a tool for chemical identification and molecular structure analysis. Other applications include the measurements of self-diffusion coefficients, magnetic fields and field homogeneity, inter-nuclear distances, and, in some cases, the water content of biological materials. (author)

  12. Green’s function theory of ferromagnetic resonance in magnetic superlattices with damping

    International Nuclear Information System (INIS)

    Qiu, R.K.; Guo, F.F.; Zhang, Z.D.

    2016-01-01

    We explore a quantum Green’s-function method to study the resonance absorption of magnetic materials. The relationship between the resonance magnon (spin wave) density and the resonance frequency of a superlattice consisting of two magnetic layers with damping and antiferromagnetic interlayer exchange coupling is studied. The effects of temperature, interlayer coupling, anisotropy, external magnetic field and damping on the the resonance frequency and resonance magnon density are investigated. The resonance excitation probability for a magnon is proportional to the resonance magnon density. In the classic methods, the imaginary part of magnetic permeability represents the resonance absorption in magnetic materials. In the quantum approach, the resonance magnon density can be used to estimate the strength of the resonance absorption. In the present work, a quantum approach is developed to study resonance absorption of magnetic materials and the results show the method to obtain a magnetic multilayered materials with both high resonance frequency and high resonance absorption.

  13. Green’s function theory of ferromagnetic resonance in magnetic superlattices with damping

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, R.K., E-mail: rkqiu@163.com [Shenyang University of Technology, Shenyang 110870 (China); Guo, F.F. [Shenyang University of Technology, Shenyang 110870 (China); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2016-02-01

    We explore a quantum Green’s-function method to study the resonance absorption of magnetic materials. The relationship between the resonance magnon (spin wave) density and the resonance frequency of a superlattice consisting of two magnetic layers with damping and antiferromagnetic interlayer exchange coupling is studied. The effects of temperature, interlayer coupling, anisotropy, external magnetic field and damping on the the resonance frequency and resonance magnon density are investigated. The resonance excitation probability for a magnon is proportional to the resonance magnon density. In the classic methods, the imaginary part of magnetic permeability represents the resonance absorption in magnetic materials. In the quantum approach, the resonance magnon density can be used to estimate the strength of the resonance absorption. In the present work, a quantum approach is developed to study resonance absorption of magnetic materials and the results show the method to obtain a magnetic multilayered materials with both high resonance frequency and high resonance absorption.

  14. Magnetic resonance imaging at Rikshospitalet

    International Nuclear Information System (INIS)

    Smith, H.J.

    1990-01-01

    During the first 18 months of operations of the nuclear magnetic resonance (NMR) unit at Rikshospitalet, 1453 NMR examinations have been performed on 1431 patients. 64% of the time has been devoted to examinations of the central nervous system and spine in children and adults, 9% of the time has been used on non-neuroradiology pediatric patients, while the rest of the time has been spent equally on ear, nose and throat, thoracic (including cardiac) and abdominal examinations in adult patients. The indications for doing NMR at Rikshospitalet are listed and discussed, and it is concluded that NMR has proved to be useful at several conditions in most organ systems. 15 refs

  15. Advances in magnetic resonance 3

    CERN Document Server

    Waugh, John S

    2013-01-01

    Advances in Magnetic Resonance, Volume 3, describes a number of important developments which are finding increasing application by chemists. The book contains five chapters and begins with a discussion of how the properties of random molecular rotations reflect themselves in NMR and how they show up, often differently, in other kinds of experiments. This is followed by separate chapters on the Kubo method, showing its equivalence to the Redfield approach in the cases of most general interest; the current state of dynamic nuclear polarization measurements in solutions and what they tell us abou

  16. Resonant and nonresonant magnetic scattering (invited)

    International Nuclear Information System (INIS)

    McWhan, D.B.; Hastings, J.B.; Kao, C.; Siddons, D.P.

    1992-01-01

    The tunability and the polarization of synchrotron radiation open up new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and they fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin-polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation

  17. Tunable Magnetic Resonance in Microwave Spintronics Devices

    Science.gov (United States)

    Chen, Yunpeng; Fan, Xin; Xie, Yunsong; Zhou, Yang; Wang, Tao; Wilson, Jeffrey D.; Simons, Rainee N.; Chui, Sui-Tat; Xiao, John Q.

    2015-01-01

    Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe based tunable microwave spintronics devices, which is 10X higher than conventional methods.

  18. Magnetic resonance imaging of Parkinsonism

    International Nuclear Information System (INIS)

    Mukai, Eiichiro; Makino, Naoki; Fujishiro, Kenichiro.

    1989-01-01

    We have analyzed magnetic resonance images in 33 patients; 18 patients with Parkinson's disease, 1 patient with diurnally fluctuating progressive dystonia, 1 patient with pure akinesia, 6 patients with multiple system atrophy, 1 patient with flunarizine induced parkinsonism, and 4 patients with unclassified parkinsonism. The MR images were obtained using a 1.5-T GE MR System. A spin-echo pulse sequence was used with a TE of 30 msec and 80 msec and a TR of 2000 msec. No signal abnormalities were seen in any patient with Parkinson's disease but 3 showed slightly decreased signal intensity of the putamen on T2-weighted sequences. Patients with diurnally fluctuating progressive dystonia and pure akinesia evidensed no abnormal findings. All six patients with multiple system atrophy demonstrated decreased signal intensity of the putamen, particularly along their lateral and posterior portions, and an enlarged substantia nigra. Atrophy of the pons and cerebellum was detected in all cases with multiple system atrophy. One case of flunarizine induced parkinsonism showed slightly decreased signal intensity of the putamen. Four cases of unclassified parkinsonism showed decreased signal in the putamen on T2-weighted sequences. Magnetic resonance imaging has the potential to become a useful diagnostic tool in the management of parkinsonism. (author)

  19. Magnetic resonance imaging of Parkinsonism

    Energy Technology Data Exchange (ETDEWEB)

    Mukai, Eiichiro [National Hospital of Nagoya (Japan); Makino, Naoki; Fujishiro, Kenichiro

    1989-06-01

    We have analyzed magnetic resonance images in 33 patients; 18 patients with Parkinson's disease, 1 patient with diurnally fluctuating progressive dystonia, 1 patient with pure akinesia, 6 patients with multiple system atrophy, 1 patient with flunarizine induced parkinsonism, and 4 patients with unclassified parkinsonism. The MR images were obtained using a 1.5-T GE MR System. A spin-echo pulse sequence was used with a TE of 30 msec and 80 msec and a TR of 2000 msec. No signal abnormalities were seen in any patient with Parkinson's disease but 3 showed slightly decreased signal intensity of the putamen on T2-weighted sequences. Patients with diurnally fluctuating progressive dystonia and pure akinesia evidensed no abnormal findings. All six patients with multiple system atrophy demonstrated decreased signal intensity of the putamen, particularly along their lateral and posterior portions, and an enlarged substantia nigra. Atrophy of the pons and cerebellum was detected in all cases with multiple system atrophy. One case of flunarizine induced parkinsonism showed slightly decreased signal intensity of the putamen. Four cases of unclassified parkinsonism showed decreased signal in the putamen on T2-weighted sequences. Magnetic resonance imaging has the potential to become a useful diagnostic tool in the management of parkinsonism. (author).

  20. Migraine and magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Younis, Samaira; Hougaard, Anders; Vestergaard, Mark B.

    2017-01-01

    Purpose of review: To present an updated and streamlined overview of the metabolic and biochemical aspect of the migraine pathophysiology based on findings from phosphorous (31P) and hydrogen (1H) magnetic resonance spectroscopy (MRS) studies. Recent findings: Despite of the variation in the meth......Purpose of review: To present an updated and streamlined overview of the metabolic and biochemical aspect of the migraine pathophysiology based on findings from phosphorous (31P) and hydrogen (1H) magnetic resonance spectroscopy (MRS) studies. Recent findings: Despite of the variation...... in the methodology and quality of the MRS migraine studies over time, some results were consistent and reproducible. 31P-MRS studies suggested reduced availability of neuronal energy and implied a mitochondrial dysfunction in the migraine brain. 1H-MRS studies reported interictal abnormalities in the excitatory...... and inhibitory neurotransmitters, glutamate and g-aminobutyric acid (GABA), suggesting persistent altered excitability in migraine patients. N-Acetylaspartate levels were decreased in migraine, probably due to a mitochondrial dysfunction and abnormal energy metabolism. The reported abnormalities may increase...

  1. Advances in mechanical detection of magnetic resonance

    International Nuclear Information System (INIS)

    Kuehn, Seppe; Hickman, Steven A.; Marohn, John A.

    2008-01-01

    The invention and initial demonstration of magnetic resonance force microscopy (MRFM) in the early 1990s launched a renaissance of mechanical approaches to detecting magnetic resonance. This article reviews progress made in MRFM in the last decade, including the demonstration of scanned probe detection of magnetic resonance (electron spin resonance, ferromagnetic resonance, and nuclear magnetic resonance) and the mechanical detection of electron spin resonance from a single spin. Force and force-gradient approaches to mechanical detection are reviewed and recent related work using attonewton sensitivity cantilevers to probe minute fluctuating electric fields near surfaces is discussed. Given recent progress, pushing MRFM to single proton sensitivity remains an exciting possibility. We will survey some practical and fundamental issues that must be resolved to meet this challenge.

  2. Investigations of the R5(SixGe1-x)4 Intermetallic Compounds by X-Ray Resonant Magnetic Scattering

    International Nuclear Information System (INIS)

    Lizhi Tan

    2008-01-01

    The XRMS experiment on the Gd 5 Ge 4 system has shown that, below the Neel temperature, T N = 127 K, the magnetic unit cells is the same as the chemical unit cell. From azimuth scans and the Q dependence of the magnetic scattering, all three Gd sites in the structure were determined to be in the same magnetic space group Pnma. The magnetic moments are aligned along the c-axis and the c-components of the magnetic moments at the three different sites are equal. The ferromagnetic slabs are stacked antiferromagnetically along the b-direction. They found an unusual order parameter curve in Gd 5 Ge 4 . A spin-reorientation transition is a possibility in Gd 5 Ge 4 , which is similar to the Tb 5 Ge 4 case. Tb 5 Ge 4 possesses the same Sm 5 Ge 4 -type crystallographic structure and the same magnetic space group as Gd 5 Ge 4 does. The difference in magnetic structure is that Tb 5 Ge 4 has a canted one but Gd 5 Ge 4 has nearly a collinear one in the low temperature antiferromagnetic phase. The competition between the magneto-crystalline anisotropy and the nearest-neighbor magnetic exchange interactions may allow a 3-dimensional canted antiferromagnetic structure in Tb 5 Ge 4 . The spin-reorientation transition in both Gd 5 Ge 4 and Tb 5 Ge 4 may arise from the competition between the magnetic anisotropy from the spin-orbit coupling of the conduction electrons and the dipolar interactions anisotropy

  3. Magnetic resonance imaging of Parkinsonism

    International Nuclear Information System (INIS)

    Nakamura, Yusaku; Takahashi, Mitsuo; Kitaguchi, Masataka; Akaneya, Yukio; Mitui, Yoshiyuki; Tanaka, Hisashi

    1991-01-01

    We studied eighteen patients affected by Parkinsonism with symptoms of tremor, bradykinesia, or rigidity using magnetic resonance imaging (MRI). Patients ranged in age from 34 to 80 years (mean 62.8±11.6 years), and the duration of their disease had been 3.8±3.2 years. MRI examinations were performed with Shimazu and Siemens superconducting magnets, operating at 0.5 and 1.5 T magnetic fields, respectively. Both T 1 - and T 2 -weighted spin echo (SE) pulse sequences were used. In eight patients (44.4%), MRI demonstrated bilateral multiple lacunar infarction of the basal ganglia. The most common abnormality identified was multiple, bilateral lacunar infarcts in the lateral portion of the putamen. The average size of the lacunar infarction of the putamen was less than half that of the entire putamen. Patients with multiple lacunar infarction were significantly older than the other patients and had lower Yahr's scores. The clinical symptoms of patients with bilateral multiple lacunar infarction of the basal ganglia were compatible with the diagnosis of arteriosclerotic Parkinsonism of akinetic rigid type. It has been suggested that multiple lacunar infarction of the basal ganglia may have led to Parkinsonism in these patients. (author)

  4. Nuclear magnetic resonance imaging method

    International Nuclear Information System (INIS)

    Johnson, G.; MacDonald, J.; Hutchison, S.; Eastwood, L.M.; Redpath, T.W.T.; Mallard, J.R.

    1984-01-01

    A method of deriving three dimensional image information from an object using nuclear magnetic resonance signals comprises subjecting the object to a continuous, static magnetic field and carrying out the following set of sequential steps: 1) exciting nuclear spins in a selected volume (90deg pulse); 2) applying non-aligned first, second and third gradients of the magnetic field; 3) causing the spins to rephase periodically by reversal of the first gradient to produce spin echoes, and applying pulses of the second gradient prior to every read-out of an echo signal from the object, to differently encode the spin in the second gradient direction for each read-out signal. The above steps 1-3 are then successively repeated with different values of gradient of the third gradient, there being a recovery interval between the repetition of successive sets of steps. Alternate echoes only are read out, the other echoes being time-reversed and ignored for convenience. The resulting signals are appropriately sampled, set out in an array and subjected to three dimensional Fourier transformation. (author)

  5. Cardiac magnetic resonance imaging in clinical practice

    Directory of Open Access Journals (Sweden)

    Adriana Dias Barranhas

    2014-01-01

    Full Text Available Objective To evaluate and describe indications, mainly diagnoses and cardiac magnetic resonance imaging findings observed in clinical practice. Materials and Methods Retrospective and descriptive study of cardiac magnetic resonance performed at a private hospital and clinic in the city of Niterói, RJ, Brazil, in the period from May 2007 to April 2011. Results The sample included a total of 1000 studies performed in patients with a mean age of 53.7 ± 16.2 years and predominance for male gender (57.2%. The majority of indications were related to assessment of myocardial perfusion at rest and under pharmacological stress (507/1000; 51%, with positive results in 36.2% of them. Suspected myocarditis was the second most frequent indication (140/1000; 14%, with positive results in 63.4% of cases. These two indications were followed by study of arrhythmias (116/1000; 12%, myocardial viability (69/1000; 7% and evaluation of cardiomyopathies (47/1000; 5%. In a subanalysis, it was possible to identify that most patients were assessed on an outpatient basis (58.42%. Conclusion Cardiac magnetic resonance has been routinely performed in clinical practice, either on an outpatient or emergency/inpatient basis, and myocardial ischemia represented the main indication, followed by investigation of myocarditis, arrhythmogenic right ventricular dysplasia and myocardial viability.

  6. Investigation of the structure of isobutylene oligomers, used in the capacity of stock for succinimide additives, by the method of proton magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Iarmoliuk, V.M.; Garun, Ia.E.; Ostroverkhov, V.G.; Pustovit, V.E.; Tikhonov, V.P.

    1980-01-01

    By the method of proton magnetic resonance, investigation was made of the structure of hydrocarbon framework of isobutylene oligomers of the Salavatsk petrochemical plant, produced by the cation polymerization of the isobutane isobutylene fraction at a temperature from -10 to +20/sup 0/ with A1C1/sub 3/ and used in the production of succinide additives. Determination was made of the qualitative and quantitative compositions of the various structures in the oligomers. It is shown, that as a rule, oligobutenes are not pure oligomers of isobutylene, but represent, at least, fragments of four structures, which can be formed on the basis of isobutylene. The content of the given structures does not affect the reaction capacity of the oligomers in respect to the maleic anhydride. It was established, that the low molecular fraction, contained in oligomers up to 5%, are not isobutylene oligomers, but represent a low molecular polymer of butene-2 and its copolymer with isobutylene.

  7. Magnetic resonance imaging of the male pelvis

    International Nuclear Information System (INIS)

    Lamarque, J.L.; Rouanet, J.P.; Pujol, J.

    1986-01-01

    The authors present their preliminary results in the investigation of the male pelvis by means of a 0.35 Tesla superconductor apparatus. They present the different sequences used. The signal of the various pelvic organs in man is analysed together with the different anatomical possibilities. Magnetic resonance imaging appears to present very important advantages. The authors consider that the major limitations involve the prostate: new sequences of investigation, in particular a long TR, should be used for the purposes of tissue differentiation [fr

  8. Transition metal nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Pregosin, P.S.

    1991-01-01

    Transition metal NMR spectroscopy has progressed enormously in recent years. New methods, and specifically solid-state methods and new pulse sequences, have allowed access to data from nuclei with relatively low receptivities with the result that chemists have begun to consider old and new problems, previously unapproachable. Moreover, theory, computational science in particular, now permits the calculation of not just 13 C, 15 N and other light nuclei chemical shifts, but heavy main-group element and transition metals as well. These two points, combined with increasing access to high field pulsed spectrometer has produced a wealth of new data on the NMR transition metals. A new series of articles concerned with measuring, understanding and using the nuclear magnetic resonance spectra of the metals of Group 3-12 is presented. (author)

  9. Gaucher's disease: Magnetic resonance findings

    International Nuclear Information System (INIS)

    Roca, M.; Gomez-Pereda, R.; Blasco, A.; Ros, L.

    1996-01-01

    The objective is to assess the role of magnetic resonance (MR) in determining the initial extension of Gaucher's disease and its complications. A retrospective study of eight patients diagnosed as having Gaucher's disease was carried out using MR. The study focused on pelvis, hip, femur, spine, liver parenchyma and splenic parenchyma. Infiltration of the cancellous portion of the vertebral bodies was observed in all but one of the patients. Three patients presented small hemangiomas in dorsal and lumbar vertebral bodies. Pelvic bone involvement was homogeneous in four cases and spotty in two, while the pelvic marrow was normal in the two patients with no vertebral infiltration. A vascular necrosis of the femoral head was detected in two cases. MR is very useful in determining the initial extension, in the early diagnosis of complications and in managing the posttreatment marrow response to assess the therapeutic efficacy. 16 refs

  10. Fetal abdominal magnetic resonance imaging

    International Nuclear Information System (INIS)

    Brugger, Peter C.; Prayer, Daniela

    2006-01-01

    This review deals with the in vivo magnetic resonance imaging (MRI) appearance of the human fetal abdomen. Imaging findings are correlated with current knowledge of human fetal anatomy and physiology, which are crucial to understand and interpret fetal abdominal MRI scans. As fetal MRI covers a period of more than 20 weeks, which is characterized not only by organ growth, but also by changes and maturation of organ function, a different MR appearance of the fetal abdomen results. This not only applies to the fetal intestines, but also to the fetal liver, spleen, and adrenal glands. Choosing the appropriate sequences, various aspects of age-related and organ-specific function can be visualized with fetal MRI, as these are mirrored by changes in signal intensities. Knowledge of normal development is essential to delineate normal from pathological findings in the respective developmental stages

  11. Fetal abdominal magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Brugger, Peter C. [Center of Anatomy and Cell Biology, Integrative Morphology Group, Medical University of Vienna, Waehringerstrasse 13, 1090 Vienna (Austria)]. E-mail: peter.brugger@meduniwien.ac.at; Prayer, Daniela [Department of Radiology, Medical University of Vienna, Waehringerguertel 18-20, 1090 Vienna (Austria)

    2006-02-15

    This review deals with the in vivo magnetic resonance imaging (MRI) appearance of the human fetal abdomen. Imaging findings are correlated with current knowledge of human fetal anatomy and physiology, which are crucial to understand and interpret fetal abdominal MRI scans. As fetal MRI covers a period of more than 20 weeks, which is characterized not only by organ growth, but also by changes and maturation of organ function, a different MR appearance of the fetal abdomen results. This not only applies to the fetal intestines, but also to the fetal liver, spleen, and adrenal glands. Choosing the appropriate sequences, various aspects of age-related and organ-specific function can be visualized with fetal MRI, as these are mirrored by changes in signal intensities. Knowledge of normal development is essential to delineate normal from pathological findings in the respective developmental stages.

  12. Single voxel magnetic resonance spectroscopy in distinguishing ...

    African Journals Online (AJOL)

    Objective: Assess diagnostic utility of combined magnetic resonance imaging and magnetic resonance spectroscopy (MRI, MRS) in differentiating focal neoplastic lesions from focal non- neoplastic (infective or degenerative) brain lesions. Design: Descriptive, analytical - prospective study. Setting: The Aga Khan University ...

  13. Magnetic resonance imaging of radiation optic neuropathy

    International Nuclear Information System (INIS)

    Zimmerman, C.F.; Schatz, N.J.; Glaser, J.S.

    1990-01-01

    Three patients with delayed radiation optic neuropathy after radiation therapy for parasellar neoplasms underwent magnetic resonance imaging. The affected optic nerves and chiasms showed enlargement and focal gadopentetate dimeglumine enhancement. The magnetic resonance imaging technique effectively detected and defined anterior visual pathway changes of radionecrosis and excluded the clinical possibility of visual loss because of tumor recurrence

  14. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... Sponsored by Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography (MRA) Transcript Welcome to Radiology Info dot ... I’d like to talk with you about magnetic resonance angiography, or as it’s commonly known, MRA. MRA ...

  15. The Juno Magnetic Field Investigation

    DEFF Research Database (Denmark)

    Connerney, J. E. P.; Benn, Mathias; Bjarnø, Jonas Bækby

    2017-01-01

    The Juno Magnetic Field investigation (MAG) characterizes Jupiter’s planetary magnetic field and magnetosphere, providing the first globally distributed and proximate measurements of the magnetic field of Jupiter. The magnetic field instrumentation consists of two independent magnetometer sensor ...

  16. Multidimensionally encoded magnetic resonance imaging.

    Science.gov (United States)

    Lin, Fa-Hsuan

    2013-07-01

    Magnetic resonance imaging (MRI) typically achieves spatial encoding by measuring the projection of a q-dimensional object over q-dimensional spatial bases created by linear spatial encoding magnetic fields (SEMs). Recently, imaging strategies using nonlinear SEMs have demonstrated potential advantages for reconstructing images with higher spatiotemporal resolution and reducing peripheral nerve stimulation. In practice, nonlinear SEMs and linear SEMs can be used jointly to further improve the image reconstruction performance. Here, we propose the multidimensionally encoded (MDE) MRI to map a q-dimensional object onto a p-dimensional encoding space where p > q. MDE MRI is a theoretical framework linking imaging strategies using linear and nonlinear SEMs. Using a system of eight surface SEM coils with an eight-channel radiofrequency coil array, we demonstrate the five-dimensional MDE MRI for a two-dimensional object as a further generalization of PatLoc imaging and O-space imaging. We also present a method of optimizing spatial bases in MDE MRI. Results show that MDE MRI with a higher dimensional encoding space can reconstruct images more efficiently and with a smaller reconstruction error when the k-space sampling distribution and the number of samples are controlled. Copyright © 2012 Wiley Periodicals, Inc.

  17. 1H and 31P nuclear magnetic resonance investigation of the interaction between 2,3-diphosphoglycerate and human normal adult hemoglobin

    International Nuclear Information System (INIS)

    Russu, I.M.; Wu, S.S.; Bupp, K.A.; Ho, N.T.; Ho, C.

    1990-01-01

    High-resolution 1 H and 31 P nuclear magnetic resonance spectroscopy has been used to investigate the binding of 2,3-diphosphoglycerate to human normal adult hemoglobin and the molecular interactions involved in the allosteric effect of the 2,3-diphosphoglycerate molecule on hemoglobin. Individual hydrogen ion NMR titration curves have been obtained for 22-26 histidyl residues of hemoglobin and for each phosphate group of 2,3-diphosphoglycerate with hemoglobin in both the deoxy and carbonmonoxy forms. The results indicate that 2,3-diphosphoglycerate binds to deoxyhemoglobin at the central cavity between the two β chains and the binding involves the β2-histidyl residues. Moreover, the results suggest that the binding site of 2,3-diphosphoglycerate to carbonmonoxyhemoglobin contains the same (or at least some of the same) amino acid residues responsible for binding in the deoxy form. As a result of the specific interactions with 2,3-diphosphoglycerate, the β2-histidyl residues make a significant contribution to the alkaline Bohr effect under these experimental conditions. These results give the first experimental demonstration that long-range electrostatic and/or conformation effects of the binding could play an important role in the allosteric effect of 2,3-diphosphoglycerate on hemoglobin. The 31 P nuclear magnetic resonance titration data for each phosphate group of 2,3-diphosphoglycerate have been used to calculate the pK values of the phosphate groups in 2,3-diphosphoglycerate bound to deoxy- and carbon-monoxyhemoglobin and the proton uptake by 2,3-diphosphoglycerate upon ligand binding to hemoglobin

  18. Proton magnetic resonance spectroscopy in schizophrenia

    International Nuclear Information System (INIS)

    Bertolino, Alessandro; Weinberger, Daniel R.

    1999-01-01

    Proton magnetic resonance spectroscopy (MRS) has become an important tool to study in vivo certain biochemical aspects of brain disorders. In the last decade this technique has been applied to the in vivo investigation of pathophysiological aspects of psychiatric disorders, extending knowledge of the related brain alterations. This review will focus on providing some background to clarify technical and biochemical issues and it will describe the studies that have been performed in schizophrenia. The results will be framed in a more general context to highlight what we have learned and what remains to be understood from the application of this technique to schizophrenia

  19. Force detection of nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Rugar, D.; Zueger, O.; Hoen, S.; Yannoni, C.S.; Vieth, H.M.; Kendrick, R.D.

    1994-01-01

    Micromechanical sensing of magnetic force was used to detect nuclear magnetic resonance with exceptional sensitivity and spatial resolution. With a 900 angstrom thick silicon nitride cantilever capable of detecting subfemtonewton forces, a single shot sensitivity of 1.6 x 10 13 protons was achieved for an ammonium nitrate sample mounted on the cantilever. A nearby millimeter-size iron particle produced a 600 tesla per meter magnetic field gradient, resulting in a spatial resolution of 2.6 micrometers in one dimension. These results suggest that magnetic force sensing is a viable approach for enhancing the sensitivity and spatial resolution of nuclear magnetic resonance microimaging

  20. Magnetic resonance tomography for trauma of the cervical spine

    International Nuclear Information System (INIS)

    Meydam, K.; Sehlen, S.; Schlenkhoff, D.; Kiricuta, J.C.; Beyer, H.K.

    1986-01-01

    Twenty patients who had suffered spinal trauma were examined by magnetic resonance tomography. Fifteen patients with first degree trauma in Erdmann's classification showed no abnormality. Magnetic resonance tomography of the cervical spine appears to be a suitable method for investigating patients with whiplash injuries. It is indicated following severe flexion injuries with subluxations and neurological symptoms, since it is the only method that can demonstrate the spinal cord directly and completely and show the extent of cord compression. For patients with thoracic trauma and rapidly developing neurological symptoms, magnetic resonance tomography is ideal for showing post-traumatic syringomyelia. Magnetic resonance tomography following whiplash injuries is recommended if plain films of the cervical spine show any abnormalities, as well as for the investigation of acute or sub-acute neurological abnormalities. The various findings are discussed. (orig.) [de

  1. Magnetic resonance tomography for trauma of the cervical spine

    Energy Technology Data Exchange (ETDEWEB)

    Meydam, K.; Sehlen, S.; Schlenkhoff, D.; Kiricuta, J.C.; Beyer, H.K.

    1986-12-01

    Twenty patients who had suffered spinal trauma were examined by magnetic resonance tomography. Fifteen patients with first degree trauma in Erdmann's classification showed no abnormality. Magnetic resonance tomography of the cervical spine appears to be a suitable method for investigating patients with whiplash injuries. It is indicated following severe flexion injuries with subluxations and neurological symptoms, since it is the only method that can demonstrate the spinal cord directly and completely and show the extent of cord compression. For patients with thoracic trauma and rapidly developing neurological symptoms, magnetic resonance tomography is ideal for showing post-traumatic syringomyelia. Magnetic resonance tomography following whiplash injuries is recommended if plain films of the cervical spine show any abnormalities, as well as for the investigation of acute or sub-acute neurological abnormalities. The various findings are discussed.

  2. Magnetic resonance elastometry using a single-sided permanent magnet

    International Nuclear Information System (INIS)

    Tan, Carl S; Marble, Andrew E; Ono, Yuu

    2012-01-01

    In this paper, we describe a magnetic resonance method of measuring material elasticity using a single-sided magnet with a permanent static field gradient. This method encodes sample velocity in a reciprocal space using Hahn spin-echoes with variable timing. The experimental results show a strong correlation between magnetic resonance signal attenuation and elasticity when an oscillating force is applied on the sample. This relationship in turn provides us with information about the displacement velocity experienced by the sample, which is inversely proportional to Young's modulus. The proposed method shows promise in offering a portable and cost-effective magnetic resonance elastography system. (paper)

  3. Artifacts in Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    Krupa, Katarzyna; Bekiesińska-Figatowska, Monika

    2015-01-01

    Artifacts in magnetic resonance imaging and foreign bodies within the patient’s body may be confused with a pathology or may reduce the quality of examinations. Radiologists are frequently not informed about the medical history of patients and face postoperative/other images they are not familiar with. A gallery of such images was presented in this manuscript. A truncation artifact in the spinal cord could be misinterpreted as a syrinx. Motion artifacts caused by breathing, cardiac movement, CSF pulsation/blood flow create a ghost artifact which can be reduced by patient immobilization, or cardiac/respiratory gating. Aliasing artifacts can be eliminated by increasing the field of view. An artificially hyperintense signal on FLAIR images can result from magnetic susceptibility artifacts, CSF/vascular pulsation, motion, but can also be found in patients undergoing MRI examinations while receiving supplemental oxygen. Metallic and other foreign bodies which may be found on and in patients’ bodies are the main group of artifacts and these are the focus of this study: e.g. make-up, tattoos, hairbands, clothes, endovascular embolization, prostheses, surgical clips, intraorbital and other medical implants, etc. Knowledge of different types of artifacts and their origin, and of possible foreign bodies is necessary to eliminate them or to reduce their negative influence on MR images by adjusting acquisition parameters. It is also necessary to take them into consideration when interpreting the images. Some proposals of reducing artifacts have been mentioned. Describing in detail the procedures to avoid or limit the artifacts would go beyond the scope of this paper but technical ways to reduce them can be found in the cited literature

  4. The investigations on the use of proton magnetic resonance in the quantitative analysis of organis compounds. Part 1. Review of analytical methods

    International Nuclear Information System (INIS)

    Ciercierska-Stoklosa, D.

    1976-01-01

    The review of papers on the application of proton magnetic resonance in quantitative analyisis of organic compounds in multicomponent mixtures has been presented. The applied techniques have been described and unified way of presentation of formulas used in calculations has been propsed. The information about precision, accuracy and detectability of the method and the possibility of improving of determination has been given. (author)

  5. Analysis and Modeling of Integrated Magnetics for LLC resonant Converters

    DEFF Research Database (Denmark)

    Li, Mingxiao; Ouyang, Ziwei; Zhao, Bin

    2017-01-01

    Shunt-inserted transformers are widely used toobtain high leakage inductance. This paper investigates thismethod in depth to make it applicable to integrate resonantinductor for the LLC resonant converters. The analysis andmodel of magnetizing inductance and leakage inductance forshunt...... transformers can provide a significantdifference. The way to obtain the desirable magnetizing andleakage inductance value for LLC resonant converters issimplified by the creation of air gaps together with a magneticshunt. The calculation and relation are validated by finiteelement analysis (FEA) simulations...

  6. Magnetic resonance in obstructive jaundice

    International Nuclear Information System (INIS)

    Gupta, R.K.; Jena, A.; Khushu, S.; Kakar, A.K.; Mishra, P.K.

    1989-01-01

    Twelve cases of obstructive jaundice in whom ultrasound failed to demonstrate the site and/or the cause of obstruction of the biliary tract were examined with magnetic resonance imaging (MRI), correctly diagnosing the site and cause of obstruction in 10 of 12 surgically proven cases. In one case of cholangiocarcinoma, the site of obstruction was well shown on MR but a definite cause could not be ascertained. In another patient who developed intermittent jaundice following surgery for choledochal cyst, MR demonstrated a solitary stone in the common hepatic duct. Surgical confirmation could not be achieved as the patient was lost to follow up. There were 6 cases of choledocholithiasis, 3 cases of gall bladder carcinoma and one case each of pancreatic adenocarcinoma and cholangiocarcinoma. It is believed that MRI will provide obstructive jaundice and will be able to minimize the use of percutaneous transhepatic cholangiography (PTC) and endoscopic retrograde cholangiopancreatography (ERCP) in view of its ability to perform multiplanar imaging in multiple sequences. 11 refs., figs., 1 tab

  7. Low rank magnetic resonance fingerprinting.

    Science.gov (United States)

    Mazor, Gal; Weizman, Lior; Tal, Assaf; Eldar, Yonina C

    2016-08-01

    Magnetic Resonance Fingerprinting (MRF) is a relatively new approach that provides quantitative MRI using randomized acquisition. Extraction of physical quantitative tissue values is preformed off-line, based on acquisition with varying parameters and a dictionary generated according to the Bloch equations. MRF uses hundreds of radio frequency (RF) excitation pulses for acquisition, and therefore high under-sampling ratio in the sampling domain (k-space) is required. This under-sampling causes spatial artifacts that hamper the ability to accurately estimate the quantitative tissue values. In this work, we introduce a new approach for quantitative MRI using MRF, called Low Rank MRF. We exploit the low rank property of the temporal domain, on top of the well-known sparsity of the MRF signal in the generated dictionary domain. We present an iterative scheme that consists of a gradient step followed by a low rank projection using the singular value decomposition. Experiments on real MRI data demonstrate superior results compared to conventional implementation of compressed sensing for MRF at 15% sampling ratio.

  8. Presurgical functional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Stippich, C.

    2010-01-01

    Functional magnetic resonance imaging (fMRI) is an important and novel neuroimaging modality for patients with brain tumors. By non-invasive measurement, localization and lateralization of brain activiation, most importantly of motor and speech function, fMRI facilitates the selection of the most appropriate and sparing treatment and function-preserving surgery. Prerequisites for the diagnostic use of fMRI are the application of dedicated clinical imaging protocols and standardization of the respective imaging procedures. The combination with diffusion tensor imaging (DTI) also enables tracking and visualization of important fiber bundles such as the pyramidal tract and the arcuate fascicle. These multimodal MR data can be implemented in computer systems for functional neuronavigation or radiation treatment. The practicability, accuracy and reliability of presurgical fMRI have been validated by large numbers of published data. However, fMRI cannot be considered as a fully established modality of diagnostic neuroimaging due to the lack of guidelines of the responsible medical associations as well as the lack of medical certification of important hardware and software components. This article reviews the current research in the field and provides practical information relevant for presurgical fMRI. (orig.) [de

  9. Endometrial cancer: magnetic resonance imaging.

    Science.gov (United States)

    Manfredi, R; Gui, B; Maresca, G; Fanfani, F; Bonomo, L

    2005-01-01

    Carcinoma of the endometrium is the most common invasive gynecologic malignancy of the female genital tract. Clinically, patients with endometrial carcinoma present with abnormal uterine bleeding. The role of magnetic resonance imaging (MRI) in endometrial carcinoma is disease staging and treatment planning. MRI has been shown to be the most valuable imaging mod-ality in this task, compared with endovaginal ultrasound and computed tomography, because of its intrinsic contrast resolution and multiplanar capability. MRI protocol includes axial T1-weighted images; axial, sagittal, and coronal T2-weighted images; and dynamic gadolinium-enhanced T1-weighted imaging. MR examination is usually performed in the supine position with a phased array multicoil using a four-coil configuration. Endometrial carcinoma is isointense with the normal endometrium and myometrium on noncontrast T1-weighted images and has a variable appearance on T2-weighted images demonstrating heterogeneous signal intensity. The appearance of noninvasive endometrial carcinoma on MRI is characterized by a normal or thickened endometrium, with an intact junctional zone and a sharp tumor-myometrium interface. Invasive endometrial carcinoma is characterized disruption or irregularity of the junctional zone by intermediate signal intensity mass on T2-weighted images. Invasion of the cervical stroma is diagnosed when the low signal intensity cervical stroma is disrupted by the higher signal intensity endometrial carcinoma. MRI in endometrial carcinoma performs better than other imaging modalities in disease staging and treatment planning. Further, the accuracy and the cost of MRI are equivalent to those of surgical staging.

  10. Endovascular interventional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Bartels, L W; Bakker, C J G

    2003-01-01

    Minimally invasive interventional radiological procedures, such as balloon angioplasty, stent placement or coiling of aneurysms, play an increasingly important role in the treatment of patients suffering from vascular disease. The non-destructive nature of magnetic resonance imaging (MRI), its ability to combine the acquisition of high quality anatomical images and functional information, such as blood flow velocities, perfusion and diffusion, together with its inherent three dimensionality and tomographic imaging capacities, have been advocated as advantages of using the MRI technique for guidance of endovascular radiological interventions. Within this light, endovascular interventional MRI has emerged as an interesting and promising new branch of interventional radiology. In this review article, the authors will give an overview of the most important issues related to this field. In this context, we will focus on the prerequisites for endovascular interventional MRI to come to maturity. In particular, the various approaches for device tracking that were proposed will be discussed and categorized. Furthermore, dedicated MRI systems, safety and compatibility issues and promising applications that could become clinical practice in the future will be discussed. (topical review)

  11. Magnetic resonance imaging and neurolupus

    International Nuclear Information System (INIS)

    Schott, A.M.; Colson, F.; Tebib, J.; Noel, E.; Bouvier, M.

    1990-01-01

    Magnetic resonance imaging (MRI) was assessed in the management of neuropsychiatric manifestations occurring in 6 SLE patients. The MRI scans were normal in 3 cases and was associated with remission of the symptoms except for a patient who experienced a chorea at the time of the examination. Abnormal MRI scans always revealed more lesions than CT scan. 2 different patterns of abnormalities seem to correspond to 2 specific disorders. In 2 patients with clinical presentation suggesting a cortical ischemia by vascular thrombosis, both MRI scans showed areas of abnormal high signal intensities located in the subcortical white matter. In one last patient, MRI scan revealed multiple focal areas of high signal intensities (on T 1 weighter scans) disseminated not only in the deep white matter but also in the gray one. These lesions could be depend upon demyelinisation which may occur by a local vascular process. This serie confirms the interest of MRI in the management of SLE brain involvement as well as it points out some problem of interpretation. This suggest further comparative studies especially at the real onset and during the course of neuro-psychiatric manifestations. At last, the coronal sections may be more informative for the diagnosis and patholophysiology than the horizontal ones [fr

  12. Magnetic resonance in multiple sclerosis

    International Nuclear Information System (INIS)

    Scotti, G.; Caputo, D.; Cazzullo, C.L.

    1986-01-01

    Magnetic Resonance Imaging was performed in more than 200 patients with clinical suspicion or knowledge of Multiple Sclerosis. One hundred and forty-seven (60 males and 87 females) had MR evidence of multiple sclerosis lesions. The MR signal of demyelinating plaques characteristically has prolonged T1 and T2 relaxation times and the T2-weighted spin-echo sequences are generally superior to the T1-weighted images because the lesions are better visualized as areas of increased signal intensity. MR is also able to detect plaques in the brainstem, cerebellum and within the cervical spinal cord. MR appears to be an important, non-invasive method for the diagnosis of Multiple Sclerosis and has proven to be diagnostically superior to CT, evoked potentials (EP) and CSF examination. In a selected group of 30 patients, with the whole battery of the relevant MS studies, MR was positive in 100%, CT in 33,3%, EP in 56% and CSF examination in 60%. In patients clinically presenting only with signs of spinal cord involvement or optic neuritis or when the clinical presentation is uncertain MR has proven to be a very useful diagnostic tool for diagnosis of MS by demonstrating unsuspected lesions in the cerebral hemispheres. (orig.)

  13. Myositis ossificans: magnetic resonance images

    International Nuclear Information System (INIS)

    Dosda, R.; Marti-Bonmati, L.; Concepcion, L.; Galant, J.

    1999-01-01

    Myositis ossificans is characterized by a benign, self-limiting, ossifying mass of the white tissue. In the present report, we describe the magnetic resonance (MR) images in three cases of myositis ossificans in pediatric patients, correlating the MR findings with those obtained with other radiological studies. The lesions were detected in three patients, two boys and one girl, ranging in age between 10 and 14 years. The nature of the lesion was confirmed histologically in all three cases. The MR images were obtained using superconductive units at 0.5 Teslas, with T1 and T2-weighted spin-echo and STIR sequences. In two patients, gadolinium-enhanced T1-weighted images were also obtained. As in any process of maturation, the proliferation/maturation ratio depends on the moment in the course of the lesion, which affects its MR features,. In acute phases, the soft tissue mass with an intraosseous, perilesional adematous reaction predominates, while annular calcification and lesser edema are characteristic of subacute episode. Myositis ossificans is very rare in children. The inflammatory response may present a radiological pattern difficult to distinguish from that of aggressive tumor or infection, especially in the acute phase. (Author) 7 refs

  14. Cardiovascular magnetic resonance in congenital heart disease

    International Nuclear Information System (INIS)

    Cazacu, A.; Ciubotaru, A.

    2010-01-01

    The increasing prevalence of congenital heart disease can be attributed to major improvements in diagnosis and treatment. Cardiovascular magnetic resonance imaging plays an important role in the clinical management strategy of patients with congenital heart disease. The development of new cardiovascular magnetic resonance (CMR) techniques allows comprehensive assessment of complex cardiac anatomy and function and provides information about the long-term residual post-operative lesions and complications of surgery. It overcomes many of the limitations of echocardiography and cardiac catheterization. This review evaluates the role of cardiovascular magnetic resonance imaging modality in the management of subject with congenital heart disease (CHD). (authors)

  15. Functional magnetic resonance imaging by visual stimulation

    International Nuclear Information System (INIS)

    Nishimura, Yukiko; Negoro, Kiyoshi; Morimatsu, Mitsunori; Hashida, Masahiro

    1996-01-01

    We evaluated functional magnetic resonance images obtained in 8 healthy subjects in response to visual stimulation using a conventional clinical magnetic resonance imaging system with multi-slice spin-echo echo planar imaging. Activation in the visual cortex was clearly demonstrated by the multi-slice experiment with a task-related change in signal intensity. In addition to the primary visual cortex, other areas were also activated by a complicated visual task. Multi-slice spin-echo echo planar imaging offers high temporal resolution and allows the three-dimensional analysis of brain function. Functional magnetic resonance imaging provides a useful noninvasive method of mapping brain function. (author)

  16. A Magnetic Resonance Measurement Technique for Rapidly Switched Gradient Magnetic Fields in a Magnetic Resonance Tomograph

    Directory of Open Access Journals (Sweden)

    K. Bartušek

    2003-01-01

    Full Text Available This paper describes a method for measuring of the gradient magnetic field in Nuclear Magnetic Resonance (NMR tomography, which is one of the modern medical diagnostic methods. A very important prerequisite for high quality imaging is a gradient magnetic field in the instrument with exactly defined properties. Nuclear magnetic resonance enables us to measure the pulse gradient magnetic field characteristics with high accuracy. These interesting precise methods were designed, realised, and tested at the Institute of Scientific Instruments (ISI of the Academy of Sciences of the Czech Republic. The first of them was the Instantaneous Frequency (IF method, which was developed into the Instantaneous Frequency of Spin Echo (IFSE and the Instantaneous Frequency of Spin Echo Series (IFSES methods. The above named methods are described in this paper and their a comparison is also presented.

  17. Investigations of the local environment and macroscopic alignment behavior of novel polymerizeable lyotropic liquid crystals using nuclear magnetic resonance

    Science.gov (United States)

    Juang, Elizabeth

    In this dissertation, a variety of NMR techniques were used to explore the local environment of novel polymerizeable lyotropic liquid crystals (LLC). The LLC monomers examined in this study self-assemble in the presence of a small amount of water to form uniform, nanometer-scale tubes with aqueous interiors. The phase architecture is retained upon photopolymerization to yield the resulting nanoporous material. By dissolving reactive precursors into the aqueous phase, well- structured nancomposite materials have also been formed. Proposed uses for these novel polymerizeable LLCs are as porous water filtration membranes, as heterogeneous organic catalysts, and as nanocomposite materials for load bearing and optical applications. In order to better exploit these polymerizeable LLCs for materials development, the local environment must be examined. In addition, the macroscopic orientation of these materials remains an important step in their advancement. Various NMR studies were conducted on these novel LLCs. NMR T1 relaxation measurements were conducted to elucidate the local environment and dynamics of the 23Na counterions located inside the aqueous channels. 2H NMR line shape analyses were used to characterize the local structure and dynamics near the hydrophilic headgroup. 29 Si NMR studies were performed on silica nanocomposites formed with these LLC structures. Finally, the macroscopic alignment behavior of these novel LLCs using shear and magnetic fields was examined.

  18. Abnormal functional-structural cingulum connectivity in mania: combined functional magnetic resonance imaging-diffusion tensor imaging investigation in different phases of bipolar disorder.

    Science.gov (United States)

    Martino, M; Magioncalda, P; Saiote, C; Conio, B; Escelsior, A; Rocchi, G; Piaggio, N; Marozzi, V; Huang, Z; Ferri, F; Amore, M; Inglese, M; Northoff, G

    2016-10-01

    The objective of the study was to investigate the relationship between structural connectivity (SC) and functional connectivity (FC) in the cingulum in bipolar disorder (BD) and its various phases. We combined resting-state functional magnetic resonance imaging and probabilistic tractographic diffusion tensor imaging to investigate FC and SC of the cingulum and its portions, the SC-FC relationship, and their correlations with clinical and neurocognitive measures on sustained attention in manic (n = 21), depressed (n = 20), and euthymic (n = 20) bipolar patients and healthy controls (HC) (n = 42). First, we found decreased FC between the anterior and posterior parts of the cingulum in manic patients when compared to depressed patients and HC. Second, we observed decreased SC of the cingulum bundle, particularly in its anterior part, in manic patients when compared to HC. Finally, alterations in the cingulum FC (but not SC) correlated with clinical severity scores while changes in the cingulum SC (but not FC) were related with neurocognitive deficits in sustained attention in BD. We demonstrate for the first time a reduction in FC and concomitantly in SC of the cingulum in mania, which correlated with psychopathological and neurocognitive parameters, respectively, in BD. This supports the central role of cingulum connectivity specifically in mania. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Reducing Field Distortion in Magnetic Resonance Imaging

    Science.gov (United States)

    Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

    2010-01-01

    A concept for a magnetic resonance imaging (MRI) system that would utilize a relatively weak magnetic field provides for several design features that differ significantly from the corresponding features of conventional MRI systems. Notable among these features are a magnetic-field configuration that reduces (relative to the conventional configuration) distortion and blurring of the image, the use of a superconducting quantum interference device (SQUID) magnetometer as the detector, and an imaging procedure suited for the unconventional field configuration and sensor. In a typical application of MRI, a radio-frequency pulse is used to excite precession of the magnetic moments of protons in an applied magnetic field, and the decaying precession is detected for a short time following the pulse. The precession occurs at a resonance frequency proportional to the strengths of the magnetic field and the proton magnetic moment. The magnetic field is configured to vary with position in a known way; hence, by virtue of the aforesaid proportionality, the resonance frequency varies with position in a known way. In other words, position is encoded as resonance frequency. MRI using magnetic fields weaker than those of conventional MRI offers several advantages, including cheaper and smaller equipment, greater compatibility with metallic objects, and higher image quality because of low susceptibility distortion and enhanced spin-lattice-relaxation- time contrast. SQUID MRI is being developed into a practical MRI method for applied magnetic flux densities of the order of only 100 T

  20. Pocket atlas of cranial magnetic resonance imaging

    International Nuclear Information System (INIS)

    Haughton, V.M.; Daniels, D.L.

    1986-01-01

    This atlas illustrates normal cerebral anatomy in magnetic resonance images. From their studies in cerebral anatomy utilizing cryomicrotome and other techniques, the authors selected more than 100 high-resolution images that represent the most clinically useful scans

  1. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... Disorders Video: The Basketball Game: An MRI Story Radiology and You Sponsored by Image/Video Gallery Your ... Explains Magnetic Resonance Angiography (MRA) Transcript Welcome to Radiology Info dot org Hello, I’m Dr. Elliot ...

  2. Fifty years of nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Martinez Valderrama, Juan Crisostomo

    1997-01-01

    Short information about the main developments of nuclear magnetic resonance during their fifty existence years is presented. Beside two examples of application (HETCOR and INADEQUATE) to the structural determination of organic compounds are described

  3. Principles of nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Pykett, I.L.; Newhouse, J.H.; Buonanno, F.S.; Brady, T.J.; Goldman, M.R.; Kistler, J.P.; Pohost, G.M.

    1982-01-01

    The physical principles which underlie the phenomenon of nuclear magnetic resonance (NMR) are presented in this primer. The major scanning methods are reviewed, and the principles of technique are discussed. A glossary of NMR terms is included

  4. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... with you about magnetic resonance angiography, or as it’s commonly known, MRA. MRA is a noninvasive test ... of the major blood vessels throughout your body. It may be performed with or without contrast material ...

  5. The role of magnetic resonance cholangiopancreatography and ...

    African Journals Online (AJOL)

    ) is accepted as the gold standard, there is a place for magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted imaging (DWI) in the diagnosis of obstructive biliary disorders. Aim: To compare the findings of MRCP with ...

  6. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... An MRI Story Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography ( ... posted: How to Obtain and Share Your Medical Images Movement Disorders Video: The Basketball Game: An MRI ...

  7. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... mild sedative prior to the examination. For more information about Magnetic Resonance Angiography of MRA or any ... Inc. (RSNA). To help ensure current and accurate information, we do not permit copying but encourage linking ...

  8. Chronic liver disease: evaluation by magnetic resonance

    International Nuclear Information System (INIS)

    Stark, D.D.; Goldberg, H.I.; Moss, A.A.; Bass, N.M.

    1984-01-01

    Magnetic resonance (MR) imaging distinguished hepatitis from fatty liver and cirrhosis in a woman with a history of alcohol abuse. Anatomic and physiologic manifestations of portal hypertension were also demonstrated by MR

  9. Nuclear Magnetic Resonance Trackbed Moisture Sensor System

    Science.gov (United States)

    2018-02-01

    In this initial phase, conducted from March 2015 through December 2016, Vista Clara and its subcontractor Zetica Rail successfully developed and tested a man-portable, non-invasive spot-check nuclear magnetic resonance (NMR) moisture sensor that dire...

  10. Suppressing magnetic island growth by resonant magnetic perturbation

    Science.gov (United States)

    Yu, Q.; Günter, S.; Lackner, K.

    2018-05-01

    The effect of externally applied resonant magnetic perturbations (RMPs) on the growth of magnetic islands is investigated based on two-fluid equations. It is found that if the local bi-normal electron fluid velocity at the resonant surface is sufficiently large, static RMPs of the same helicity and of moderate amplitude can suppress the growth of magnetic islands in high-temperature plasmas. These islands will otherwise grow, driven by an unfavorable plasma current density profile and bootstrap current perturbation. These results indicate that the error field can stabilize island growth, if the error field amplitude is not too large and the local bi-normal electron fluid velocity is not too low. They also indicate that applied rotating RMPs with an appropriate frequency can be utilized to suppress island growth in high-temperature plasmas, even for a low bi-normal electron fluid velocity. A significant change in the local equilibrium plasma current density gradient by small amplitude RMPs is found for realistic plasma parameters, which are important for the island stability and are expected to be more important for fusion reactors with low plasma resistivity.

  11. Can magnetic resonance imaging differentiate undifferentiated arthritis?

    DEFF Research Database (Denmark)

    Østergaard, Mikkel; Duer, Anne; Hørslev-Petersen, K

    2005-01-01

    A high sensitivity for the detection of inflammatory and destructive changes in inflammatory joint diseases makes magnetic resonance imaging potentially useful for assigning specific diagnoses, such as rheumatoid arthritis and psoriatic arthritis in arthritides, that remain undifferentiated after...... conventional clinical, biochemical and radiographic examinations. With recent data as the starting point, the present paper describes the current knowledge on magnetic resonance imaging in the differential diagnosis of undifferentiated arthritis....

  12. Nuclear magnetic resonance spectroscopy and imaging

    International Nuclear Information System (INIS)

    Jiang Weiping; Wang Qi; Zhou Xin

    2013-01-01

    This paper briefly introduces the basic principle of nuclear magnetic resonance (NMR). Protein's structures and functions and dynamics studied by liquid NMR are elaborated; methods for enhancing the resolution of solid state NMR and its applications are discussed; the principle of magnetic resonance imaging (MRI) is interpreted, and applications in different aspects are reviewed. Finally, the progress of NMR is commented. (authors)

  13. Concepts and indications of abdominal magnetic resonance

    International Nuclear Information System (INIS)

    Murillo Viera, Wendy

    2012-01-01

    A literature review and conceptualization was performed of the main indications of magnetic resonance studies of the abdomen and the characteristic findings for each sequence, according to organ and pathology. The radiologist has had in mind main indications for magnetic resonance studies of the abdomen, with the purpose to guide the clinician in the choice of imaging modality that works best for the patient at diagnosis [es

  14. Magnetic resonance imaging of muscle tears

    International Nuclear Information System (INIS)

    De Smet, A.A.; Fisher, D.R.; Heiner, J.P.; Keene, J.S.

    1990-01-01

    Magnetic resonance scans were obtained on 17 patients with acute, subacute, or chronic muscle tears. These patients presented with complaints of persistent pain or a palpable mass. Magnetic resonance findings were characterized according to alterations in muscle shape and the presence of abnormal high signal within the injured muscle. These areas of high signal were noted on both T1-weighted and T2-weighted scans and were presumed to represent areas of intramuscular hemorrhage. (orig.)

  15. Clinical magnetic resonance: imaging and spectroscopy

    International Nuclear Information System (INIS)

    Andrew, E.R.; Bydder, Graeme; Griffiths, John; Iles, Richard; Styles, Peter

    1990-01-01

    This book begins with a readable, comprehensive but non-mathematical introduction to the basic underlying principles of magnetic resonance. Further chapters include information on the theory and principles of MRI and MRS, the interpretation of MR images, the clinical applications and scope of MRI and MRS, practical aspects of spectroscopy and magnetic resonance, and also the practical problems associated with the siting, safety and operation of large MRI and MRS equipment. (author)

  16. Magnetic Resonance Imaging of Surgical Implants Made from Weak Magnetic Materials

    Science.gov (United States)

    Gogola, D.; Krafčík, A.; Štrbák, O.; Frollo, I.

    2013-08-01

    Materials with high magnetic susceptibility cause local inhomogeneities in the main field of the magnetic resonance (MR) tomograph. These inhomogeneities lead to loss of phase coherence, and thus to a rapid loss of signal in the image. In our research we investigated inhomogeneous field of magnetic implants such as magnetic fibers, designed for inner suture during surgery. The magnetic field inhomogeneities were studied at low magnetic planar phantom, which was made from four thin strips of magnetic tape, arranged grid-wise. We optimized the properties of imaging sequences with the aim to find the best setup for magnetic fiber visualization. These fibers can be potentially exploited in surgery for internal stitches. Stitches can be visualized by the magnetic resonance imaging (MRI) method after surgery. This study shows that the imaging of magnetic implants is possible by using the low field MRI systems, without the use of complicated post processing techniques (e.g., IDEAL).

  17. Nuclear magnetic resonance method and apparatus

    International Nuclear Information System (INIS)

    Burl, M.; Young, I.R.

    1984-01-01

    A method and apparatus for determining the rate of flow of a liquid in a selected region of a body by nuclear magnetic resonance techniques are described. The method includes a sequence of applying a first magnetic pulse effective to excite nuclear magnetic resonance of a chosen nucleus within the liquid preferentially in a slice of the body which includes the selected region. A period of time (tsub(D)) is waited and then a second magnetic pulse is applied which is effective to excite nuclear magnetic resonance of the nuclei preferentially in the slice, and the free induction decay signal is measured. The whole sequence is repeated for different values of the period of time (tsub(D)). The variation in the value of the measured signal with tsub(D) is then related to the rate of flow of the liquid through the slice. (author)

  18. Investigation of the role of electron cyclotron resonance heating and magnetic configuration on the suprathermal ion population in the stellarator TJ-II using a luminescent probe

    Science.gov (United States)

    Martínez, M.; Zurro, B.; Baciero, A.; Jiménez-Rey, D.; Tribaldos, V.

    2018-02-01

    Numerous observation exist of a population of high energetic ions with energies well above the corresponding thermal values in plasmas generated by electron cyclotron resonance (ECR) heating in TJ-II stellarator and in other magnetically confined plasmas devices. In this work we study the impact of ECR heating different conditions (positions and powers) on fast ions escaping from plasmas in the TJ-II stellarator. For this study, an ion luminescent probe operated in counting mode is used to measure the energy distribution of suprathermal ions, in the range from 1 to 30 keV. It is observed that some suprathermal ions characteristics (such as temperature, particle and energy fluxes) are related directly with the gyrotron power and focus position of the heating beam in the plasma. Moreover, it is found that suprathermal ion characteristics vary during a magnetic configuration scan (performed along a single discharge). By investigating the suprathermal ions escaping from plasmas generated using two gyrotrons, one with fixed power and the other modulated (on/off) at low frequency (10 Hz), the de-confinement time of the suprathermal ions can be measured, which is of the order of a few milliseconds (power balance is used to understand the de-confinement times in terms of the interaction of suprathermal ions and plasma components. This model also can be used to interpret experimental results of energy loss due to suprathermal ions. Finally, observations of increases (peaks) in the population of escaping suprathermal ions, which are well localized at discrete energies, is documented, these peaks being observed in the energy distributions along a discharge.

  19. Investigating the prediction value of multiparametric magnetic resonance imaging at 3 T in response to neoadjuvant chemotherapy in breast cancer

    International Nuclear Information System (INIS)

    Minarikova, Lenka; Bogner, Wolfgang; Zaric, Olgica; Trattnig, Siegfried; Gruber, Stephan; Pinker, Katja; Valkovic, Ladislav; Bago-Horvath, Zsuzsanna; Bartsch, Rupert; Helbich, Thomas H.

    2017-01-01

    To explore the predictive value of parameters derived from diffusion-weighted imaging (DWI) and contrast-enhanced (CE)-MRI at different time-points during neoadjuvant chemotherapy (NACT) in breast cancer. Institutional review board approval and written, informed consent from 42 breast cancer patients were obtained. The patients were investigated before and at three different time-points during neoadjuvant chemotherapy (NACT) using tumour diameter and volume from CE-MRI and ADC values obtained from drawn 2D and segmented 3D regions of interest. Prediction of pathologic complete response (pCR) was evaluated using the area under the curve (AUC) of receiver operating characteristic analysis. There was no significant difference between pathologic complete response and non-pCR in baseline size measures (p > 0.39). Diameter change was significantly different in pCR (p < 0.02) before the mid-therapy point. The best predictor was lesion diameter change observed before mid-therapy (AUC = 0.93). Segmented volume was not able to differentiate between pCR and non-pCR at any time-point. The ADC values from 3D-ROI were not significantly different from 2D data (p = 0.06). The best AUC (0.79) for pCR prediction using DWI was median ADC measured before mid-therapy of NACT. The results of this study should be considered in NACT monitoring planning, especially in MRI protocol designing and time point selection. (orig.)

  20. Investigating the prediction value of multiparametric magnetic resonance imaging at 3 T in response to neoadjuvant chemotherapy in breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Minarikova, Lenka; Bogner, Wolfgang; Zaric, Olgica; Trattnig, Siegfried; Gruber, Stephan [Medical University of Vienna, High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna (Austria); Pinker, Katja [Medical University of Vienna, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Memorial Sloan-Kettering Cancer Center, Molecular Imaging and Therapy Service, New York, NY (United States); Valkovic, Ladislav [Medical University of Vienna, High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna (Austria); Slovak Academy of Sciences, Department of Imaging Methods, Institute of Measurement Science, Bratislava (Slovakia); University of Oxford, John Radcliffe Hospital, Oxford Centre for Clinical Magnetic Resonance Research, Oxford (United Kingdom); Bago-Horvath, Zsuzsanna [Medical University of Vienna, Department of Pathology, Comprehensive Cancer Center, Vienna (Austria); Bartsch, Rupert [Medical University of Vienna, Clinical Division of Oncology, Department of Medicine I, Vienna (Austria); Helbich, Thomas H. [Medical University of Vienna, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria)

    2017-05-15

    To explore the predictive value of parameters derived from diffusion-weighted imaging (DWI) and contrast-enhanced (CE)-MRI at different time-points during neoadjuvant chemotherapy (NACT) in breast cancer. Institutional review board approval and written, informed consent from 42 breast cancer patients were obtained. The patients were investigated before and at three different time-points during neoadjuvant chemotherapy (NACT) using tumour diameter and volume from CE-MRI and ADC values obtained from drawn 2D and segmented 3D regions of interest. Prediction of pathologic complete response (pCR) was evaluated using the area under the curve (AUC) of receiver operating characteristic analysis. There was no significant difference between pathologic complete response and non-pCR in baseline size measures (p > 0.39). Diameter change was significantly different in pCR (p < 0.02) before the mid-therapy point. The best predictor was lesion diameter change observed before mid-therapy (AUC = 0.93). Segmented volume was not able to differentiate between pCR and non-pCR at any time-point. The ADC values from 3D-ROI were not significantly different from 2D data (p = 0.06). The best AUC (0.79) for pCR prediction using DWI was median ADC measured before mid-therapy of NACT. The results of this study should be considered in NACT monitoring planning, especially in MRI protocol designing and time point selection. (orig.)

  1. Investigation of the subcellular architecture of L7 neurons of Aplysia californica using magnetic resonance microscopy (MRM) at 7.8 microns.

    Science.gov (United States)

    Lee, Choong H; Flint, Jeremy J; Hansen, Brian; Blackband, Stephen J

    2015-06-10

    Magnetic resonance microscopy (MRM) is a non-invasive diagnostic tool which is well-suited to directly resolve cellular structures in ex vivo and in vitro tissues without use of exogenous contrast agents. Recent advances in its capability to visualize mammalian cellular structure in intact tissues have reinvigorated analytical interest in aquatic cell models whose previous findings warrant up-to-date validation of subcellular components. Even if the sensitivity of MRM is less than other microscopic technologies, its strength lies in that it relies on the same image contrast mechanisms as clinical MRI which make it a unique tool for improving our ability to interpret human diagnostic imaging through high resolution studies of well-controlled biological model systems. Here, we investigate the subcellular MR signal characteristics of isolated cells of Aplysia californica at an in-plane resolution of 7.8 μm. In addition, direct correlation and positive identification of subcellular architecture in the cells is achieved through well-established histology. We hope this methodology will serve as the groundwork for studying pathophysiological changes through perturbation studies and allow for development of disease-specific cellular modeling tools. Such an approach promises to reveal the MR contrast changes underlying cellular mechanisms in various human diseases, for example in ischemic stroke.

  2. Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI).

    Science.gov (United States)

    Kojima, Masazumi; Nakagami, Hiroaki

    2002-12-01

    The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T(2)) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T(2) and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T(2) of (1)H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed.

  3. Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI)

    International Nuclear Information System (INIS)

    Kojima, Masazumi; Nakagami, Hiroaki

    2002-01-01

    The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T 2 ) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T 2 and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T 2 of 1 H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed. (author)

  4. Magnetic resonance imaging of the bone marrow

    International Nuclear Information System (INIS)

    Baur-Melnyk, Andrea

    2013-01-01

    The first book devoted to MRI of the bone marrow. Describes the MRI appearances of normal bone marrows and the full range of bone marrow disorders. Discusses the role of advanced MRI techniques and contrast enhancement. On account of its unrivalled imaging capabilities and sensitivity, magnetic resonance imaging (MRI) is considered the modality of choice for the investigation of physiologic and pathologic processes affecting the bone marrow. This book describes the MRI appearances of both the normal bone marrow, including variants, and the full range of bone marrow disorders. Detailed discussion is devoted to malignancies, including multiple myeloma, lymphoma, chronic myeloproliferative disorders, leukemia, and bone metastases. Among the other conditions covered are benign and malignant compression fractures, osteonecrosis, hemolytic anemia, Gaucher's disease, bone marrow edema syndrome, trauma, and infective and non-infective inflammatory disease. Further chapters address the role of MRI in assessing treatment response, the use of contrast media, and advanced MRI techniques. Magnetic Resonance Imaging of the Bone Marrow represents an ideal reference for both novice and experienced practitioners.

  5. Magnetic Resonance Imaging Evaluation of Cardiac Masses

    International Nuclear Information System (INIS)

    Braggion-Santos, Maria Fernanda; Koenigkam-Santos, Marcel; Teixeira, Sara Reis; Volpe, Gustavo Jardim; Trad, Henrique Simão; Schmidt, André

    2013-01-01

    Cardiac tumors are extremely rare; however, when there is clinical suspicion, proper diagnostic evaluation is necessary to plan the most appropriate treatment. In this context, cardiovascular magnetic resonance imaging (CMRI) plays an important role, allowing a comprehensive characterization of such lesions. To review cases referred to a CMRI Department for investigation of cardiac and paracardiac masses. To describe the positive case series with a brief review of the literature for each type of lesion and the role of cardiovascular magnetic resonance imaging in evaluation. Between August 2008 and December 2011, all cases referred for CMRI with suspicion of tumor involving the heart were reviewed. Cases with positive histopathological diagnosis, clinical evolution or therapeutic response compatible with the clinical suspicion and imaging findings were selected. Among the 13 cases included in our study, eight (62%) had histopathological confirmation. We describe five benign tumors (myxomas, rhabdomyoma and fibromas), five malignancies (sarcoma, lymphoma, Richter syndrome involving the heart and metastatic disease) and three non-neoplastic lesions (pericardial cyst, intracardiac thrombus and infectious vegetation). CMRI plays an important role in the evaluation of cardiac masses of non-neoplastic and neoplastic origin, contributing to a more accurate diagnosis in a noninvasive manner and assisting in treatment planning, allowing safe clinical follow-up with good reproducibility

  6. Magnetic resonance spectroscopy as an imaging method

    International Nuclear Information System (INIS)

    Bomsdorf, H.; Imme, M.; Jensen, D.; Kunz, D.; Menhardt, W.; Ottenberg, K.; Roeschmann, P.; Schmidt, K.H.; Tschendel, O.; Wieland, J.

    1990-01-01

    An experimental Magnetic Resonance (MR) system with 4 tesla flux density was set up. For that purpose a data acquisition system and RF coils for resonance frequencies up to 170 MHz were developed. Methods for image guided spectroscopy as well as spectroscopic imaging focussing on the nuclei 1 H and 13 C were developed and tested on volunteers and selected patients. The advantages of the high field strength with respect to spectroscopic studies were demonstrated. Developments of a new fast imaging technique for the acquisition of scout images as well as a method for mapping and displaying the magnetic field inhomogeneity in-vivo represent contributions to the optimisation of the experimental procedure in spectroscopic studies. Investigations on the interaction of RF radiation with the exposed tissue allowed conclusions regarding the applicability of MR methods at high field strengths. Methods for display and processing of multi-dimensional spectroscopic imaging data sets were developed and existing methods for real-time image synthesis were extended. Results achieved in the field of computer aided analysis of MR images comprised new techniques for image background detection, contour detection and automatic image interpretation as well as knowledge bases for textural representation of medical knowledge for diagnosis. (orig.) With 82 refs., 3 tabs., 75 figs [de

  7. Magnetic resonance imaging of the bone marrow

    Energy Technology Data Exchange (ETDEWEB)

    Baur-Melnyk, Andrea (ed.) [Klinikum der Univ. Muenchen (Germany). Inst. fuer Klinische Radiologie

    2013-08-01

    The first book devoted to MRI of the bone marrow. Describes the MRI appearances of normal bone marrows and the full range of bone marrow disorders. Discusses the role of advanced MRI techniques and contrast enhancement. On account of its unrivalled imaging capabilities and sensitivity, magnetic resonance imaging (MRI) is considered the modality of choice for the investigation of physiologic and pathologic processes affecting the bone marrow. This book describes the MRI appearances of both the normal bone marrow, including variants, and the full range of bone marrow disorders. Detailed discussion is devoted to malignancies, including multiple myeloma, lymphoma, chronic myeloproliferative disorders, leukemia, and bone metastases. Among the other conditions covered are benign and malignant compression fractures, osteonecrosis, hemolytic anemia, Gaucher's disease, bone marrow edema syndrome, trauma, and infective and non-infective inflammatory disease. Further chapters address the role of MRI in assessing treatment response, the use of contrast media, and advanced MRI techniques. Magnetic Resonance Imaging of the Bone Marrow represents an ideal reference for both novice and experienced practitioners.

  8. Resonance double magnetic bremsstrahlung in a strong magnetic field

    International Nuclear Information System (INIS)

    Fomin, P.I.; Kholodov, R.I.

    2003-01-01

    The possibility of resonance double magnetic bremsstrahlung in the approximation of weakly excited electron states in a strong external magnetic field is analyzed. The differential probability of this process in the Breit-Wigner form is obtained. The probability of double magnetic bremsstrahlung (second-order process of perturbation theory) is compared with the probability of magnetic bremsstrahlung (first-order process of perturbation theory)

  9. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... a powerful magnetic field, radio waves and a computer to produce detailed pictures of the brain and ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ...

  10. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... a powerful magnetic field, radio waves and a computer to produce detailed pictures of the inside of ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ...

  11. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... help detect certain chronic diseases of the nervous system, such as multiple sclerosis diagnose problems with the ... the magnet. Some MRI units, called short-bore systems , are designed so that the magnet does not ...

  12. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI) of the head uses a powerful magnetic field, radio waves and a computer to produce detailed ... there’s a possibility you are pregnant. The magnetic field is not harmful, but it may cause some ...

  13. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... their nature and the strength of the MRI magnet. Many implanted devices will have a pamphlet explaining ... large cylinder-shaped tube surrounded by a circular magnet. Your child will lie on a moveable examination ...

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... their nature and the strength of the MRI magnet. Many implanted devices will have a pamphlet explaining ... large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table ...

  15. Magnetic resonance imaging of the transplanted kidney

    International Nuclear Information System (INIS)

    Jennerholm, S.; Backman, U.; Bohman, S.O.; Hemmingsson, A.; Nyman, R.; Uppsala Univ. Hospital; Huddinge Hospital

    1990-01-01

    In this study, long-term renal transplants were investigated with magnetic resonance (MR) imaging, and the results were correlated to histopathology and graft function. Seventeen patients were investigated with MR one to 10 years after transplantation and with simultaneous ultrasonographically guided cortical needle biopsy and function tests. Histopathology included semiquantitative grading of degree of fibrosis and quantitation of ratios of tubular structures to interstitial tissue. The correlation between the histopathological assessment of interstitial fibrosis and graft function was good. Poor differentiation between the renal cortex and the renal medulla at MR imaging was correlated to high degree of interstitial fibrosis in the kidney transplants as well as to reduced graft function. MR examination may thus be of value in the evaluation of long-term renal transplants with chronic functional changes. (orig./MG)

  16. Magnetic islands created by resonant helical windings

    International Nuclear Information System (INIS)

    Fernandes, A.S.; Heller, M.V.; Caldas, I.L.

    1986-01-01

    The triggering of disruptive instabilities by resonant helical windings in large aspect-ratio tokamaks is associated to destruction of magnetic surfaces. The Chirikov condition is applied to estimate analytically the helical winding current thresholds for ergodization of the magnetic field lines. (Autor) [pt

  17. Topical questions in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Andrew, E.R.; Florida Univ., Gainesville, FL; Florida Univ., Gainesville, FL

    1989-01-01

    This paper examines a number of practical questions concerning magnetic resonance imaging. These include the choice of operating magnetic field strength, the problem of siting and screening, a procedure for securing precise slice selection and the use of paramagnetic contrast agents. (author). 5 refs

  18. Non-invasive investigation of the saturated/unsaturated zone with magnetic resonance sounding - a field example at the testsite Fuhrberger Feld near Hannover, Germany

    Science.gov (United States)

    Costabel, S.; Noell, U.; Ganz, C.

    2012-04-01

    Magnetic resonance sounding (MRS) is a non-invasive geophysical method for groundwater prospection that uses the principle of nuclear magnetic resonance (NMR) in the Earth's magnetic field. Its unique property distinct from other hydrogeophysical methods is the direct sensitivity to the amount of water, i.e. to the amount of 1H nuclei in the subsurface. Because MRS is normally used to investigate the water content of the saturated zone and to characterize aquifer structures, the standard application is optimized for 1D-measurements in depths from several to several tens of meters. However, our investigations show that MRS has also the potential to contribute substantially to the study of groundwater recharge if the sensitivity of the method for the unsaturated zone and for the transition to the saturated zone is increased by using a modified measurement setup and adjusted interpretation schemes. We conducted MRS test measurements with the focus on the very shallow subsurface in the range of some few decimeters down to the groundwater table in a depth of 3 m. The test site is located in the area Fuhrberger Feld about 30 km north-east of Hannover, Germany, which comprises an unconfined sandy aquifer of 20 to 30-m thickness. Previous studies have discovered the soil physical characteristics of the site with tension infiltrometer measurements and tracer irrigation experiments in the field, as well as with water retention measurements in the laboratory. In addition, several infiltration experiments with dye tracer were conducted and monitored with electrical resistivity tomography (ERT), tensiometers and TDR devices. For the MRS measurements at the testsite, a serious challenge was the intense electromagnetic noise consisting of large spiky radio signals and harmonic components, respectively. A special combination of new processing techniques was developed to isolate and interpret the NMR signals with amplitudes of approximately 5 to 14 nV. The standard inversion of the

  19. Prebiopsy magnetic resonance spectroscopy and imaging in the diagnosis of prostate cancer

    International Nuclear Information System (INIS)

    Kumar, V.; Jagannathan, N.R.; Thulkar, S.; Kumar, R.

    2012-01-01

    Existing screening investigations for the diagnosis of early prostate cancer lack specificity, resulting in a high negative biopsy rate. There is increasing interest in the use of various magnetic resonance methods for improving the yield of transrectal ultrasound-guided biopsies of the prostate in men suspected to have prostate cancer. We review the existing status of such investigations. A literature search was carried out using the Pubmed database to identify articles related to magnetic resonance methods for diagnosing prostate cancer. References from these articles were also extracted and reviewed. Recent studies have focused on prebiopsy magnetic resonance investigations using conventional magnetic resonance imaging, dynamic contrast enhanced magnetic resonance imaging, diffusion weighted magnetic resonance imaging, magnetization transfer imaging and magnetic resonance spectroscopy of the prostate. This marks a shift from the earlier strategy of carrying out postbiopsy magnetic resonance investigations. Prebiopsy magnetic resonance investigations has been useful in identifying patients who are more likely to have a biopsy positive for malignancy. Prebiopsy magnetic resonance investigations has a potential role in increasing specificity of screening for early prostate cancer. It has a role in the targeting of biopsy sites, avoiding unnecessary biopsies and predicting the outcome of biopsies. (author)

  20. Quantum transport in coupled resonators enclosed synthetic magnetic flux

    International Nuclear Information System (INIS)

    Jin, L.

    2016-01-01

    Quantum transport properties are instrumental to understanding quantum coherent transport processes. Potential applications of quantum transport are widespread, in areas ranging from quantum information science to quantum engineering, and not restricted to quantum state transfer, control and manipulation. Here, we study light transport in a ring array of coupled resonators enclosed synthetic magnetic flux. The ring configuration, with an arbitrary number of resonators embedded, forms a two-arm Aharonov–Bohm interferometer. The influence of magnetic flux on light transport is investigated. Tuning the magnetic flux can lead to resonant transmission, while half-integer magnetic flux quantum leads to completely destructive interference and transmission zeros in an interferometer with two equal arms. -- Highlights: •The light transport is investigated through ring array of coupled resonators enclosed synthetic magnetic field. •Aharonov–Bohm ring interferometer of arbitrary configuration is investigated. •The half-integer magnetic flux quantum leads to destructive interference and transmission zeros for two-arm at equal length. •Complete transmission is available via tuning synthetic magnetic flux.

  1. Basis of the nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Bahceli, S.

    1996-08-01

    The aim of this book which is translated from English language is to explain the physical and mathematical basis of nuclear magnetic resonance (NMR). There are nine chapters covering different aspects of NMR. In the firs chapter fundamental concepts of quantum mechanics are given at a level suitable for readers to understand NMR fully. The remaining chapters discuss the magnetic properties of nucleus, the interactions between atoms and molecules, continuous wave NMR, pulsed NMR, nuclear magnetic relaxation and NMR of liquids

  2. Magnetic nanoparticles in magnetic resonance imaging and diagnostics.

    Science.gov (United States)

    Rümenapp, Christine; Gleich, Bernhard; Haase, Axel

    2012-05-01

    Magnetic nanoparticles are useful as contrast agents for magnetic resonance imaging (MRI). Paramagnetic contrast agents have been used for a long time, but more recently superparamagnetic iron oxide nanoparticles (SPIOs) have been discovered to influence MRI contrast as well. In contrast to paramagnetic contrast agents, SPIOs can be functionalized and size-tailored in order to adapt to various kinds of soft tissues. Although both types of contrast agents have a inducible magnetization, their mechanisms of influence on spin-spin and spin-lattice relaxation of protons are different. A special emphasis on the basic magnetism of nanoparticles and their structures as well as on the principle of nuclear magnetic resonance is made. Examples of different contrast-enhanced magnetic resonance images are given. The potential use of magnetic nanoparticles as diagnostic tracers is explored. Additionally, SPIOs can be used in diagnostic magnetic resonance, since the spin relaxation time of water protons differs, whether magnetic nanoparticles are bound to a target or not.

  3. Magnetic resonance imaging of the fetal brain.

    Science.gov (United States)

    Tee, L Mf; Kan, E Yl; Cheung, J Cy; Leung, W C

    2016-06-01

    This review covers the recent literature on fetal brain magnetic resonance imaging, with emphasis on techniques, advances, common indications, and safety. We conducted a search of MEDLINE for articles published after 2010. The search terms used were "(fetal OR foetal OR fetus OR foetus) AND (MR OR MRI OR [magnetic resonance]) AND (brain OR cerebral)". Consensus statements from major authorities were also included. As a result, 44 relevant articles were included and formed the basis of this review. One major challenge is fetal motion that is largely overcome by ultra-fast sequences. Currently, single-shot fast spin-echo T2-weighted imaging remains the mainstay for motion resistance and anatomical delineation. Recently, a snap-shot inversion recovery sequence has enabled robust T1-weighted images to be obtained, which is previously a challenge for standard gradient-echo acquisitions. Fetal diffusion-weighted imaging, diffusion tensor imaging, and magnetic resonance spectroscopy are also being developed. With multiplanar capabilities, superior contrast resolution and field of view, magnetic resonance imaging does not have the limitations of sonography, and can provide additional important information. Common indications include ventriculomegaly, callosum and posterior fossa abnormalities, and twin complications. There are safety concerns about magnetic resonance-induced heating and acoustic damage but current literature showed no conclusive evidence of deleterious fetal effects. The American College of Radiology guideline states that pregnant patients can be accepted to undergo magnetic resonance imaging at any stage of pregnancy if risk-benefit ratio to patients warrants that the study be performed. Magnetic resonance imaging of the fetal brain is a safe and powerful adjunct to sonography in prenatal diagnosis. It can provide additional information that aids clinical management, prognostication, and counselling.

  4. Magnetic resonance imaging: effects of magnetic field strength

    International Nuclear Information System (INIS)

    Crooks, L.E.; Arakawa, M.; Hoenninger, J.; McCarten, B.; Watts, J.; Kaufman, L.

    1984-01-01

    Magnetic resonance images of the head, abdomen, and pelvis of normal adult men were obtained using varying magnetic field strength, and measurements of T1 and T2 relaxations and of signal-to-noise (SN) ratios were determined. For any one spin echo sequence, gray/white matter contrast decreases and muscle/fat contrast increases with field. SN levels rise rapidly up to 3.0 kgauss and then change more slowly, actually dropping for muscle. The optimum field for magnetic resonance imaging depends on tissue type, body part, and imaging sequence, so that it does not have a unique value. Magnetic resonance systems that operate in the 3.0-5.0 kgauss range achieve most or all of the gains that can be achieved by higher magnetic fields

  5. Predictors of long-term pain and disability in patients with low back pain investigated by magnetic resonance imaging: A longitudinal study

    Directory of Open Access Journals (Sweden)

    Sampson Madeleine

    2011-10-01

    Full Text Available Abstract Background It is possible that clinical outcome of low back pain (LBP differs according to the presence or absence of spinal abnormalities on magnetic resonance imaging (MRI, in which case there could be value in using MRI findings to refine case definition of LBP in epidemiological research. We therefore conducted a longitudinal study to explore whether spinal abnormalities on MRI for LBP predict prognosis after 18 months. Methods A consecutive series of patients aged 20-64 years, who were investigated by MRI because of mechanical LBP (median duration of current episode 16.2 months, were identified from three radiology departments, and those who agreed completed self-administered questionnaires at baseline and after a mean follow-up period of 18.5 months (a mean of 22.2 months from MRI investigation. MRI scans were assessed blind to other clinical information, according to a standardised protocol. Associations of baseline MRI findings with pain and disability at follow-up, adjusted for treatment and for other potentially confounding variables, were assessed by Poisson regression and summarised by prevalence ratios (PRs with their 95% confidence intervals (CIs. Results Questionnaires were completed by 240 (74% of the patients who had agreed to be followed up. Among these 111 men and 129 women, 175 (73% reported LBP in the past four weeks, 89 (37% frequent LBP, and 72 (30% disabling LBP. In patients with initial disc degeneration there was an increased risk of frequent (PR 1.3, 95%CI 1.0-1.9 and disabling LBP (PR 1.7, 95%CI 1.1-2.5 at follow-up. No other associations were found between MRI abnormalities and subsequent outcome. Conclusions Our findings suggest that the MRI abnormalities examined are not major predictors of outcome in patients with LBP. They give no support to the use of MRI findings as a way of refining case definition for LBP in epidemiological research.

  6. Solid-State Nuclear Magnetic Resonance Investigation of the Structural Topology and Lipid Interactions of a Viral Fusion Protein Chimera Containing the Fusion Peptide and Transmembrane Domain.

    Science.gov (United States)

    Yao, Hongwei; Lee, Myungwoon; Liao, Shu-Yu; Hong, Mei

    2016-12-13

    The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of parainfluenza virus 5 (PIV5) fusion protein F using solid-state nuclear magnetic resonance. These studies provide structural information about the two domains when they are spatially well separated in the fusion process. To investigate how these two domains are structured relative to each other in the postfusion state, when the ectodomain forms a six-helix bundle that is thought to force the FP and TMD together in the membrane, we have now expressed and purified a chimera of the FP and TMD, connected by a Gly-Lys linker, and measured the chemical shifts and interdomain contacts of the protein in several lipid membranes. The FP-TMD chimera exhibits α-helical chemical shifts in all the membranes examined and does not cause strong curvature of lamellar membranes or membranes with negative spontaneous curvature. These properties differ qualitatively from those of the separate peptides, indicating that the FP and TMD interact with each other in the lipid membrane. However, no 13 C- 13 C cross peaks are observed in two-dimensional correlation spectra, suggesting that the two helices are not tightly associated. These results suggest that the ectodomain six-helix bundle does not propagate into the membrane to the two hydrophobic termini. However, the loosely associated FP and TMD helices are found to generate significant negative Gaussian curvature to membranes that possess spontaneous positive curvature, consistent with the notion that the FP-TMD assembly may

  7. Ultra high field magnetic resonance imaging

    International Nuclear Information System (INIS)

    Lethimonnier, F.; Vedrine, P.

    2007-01-01

    Understanding human brain function, brain development and brain dysfunction is one of the great challenges of the twenty first century. Biomedical imaging has now run up against a number of technical constraints that are exposing limits to its potential. In order to overcome the current limits to high-field magnetic resonance cerebral imaging (MRI) and unleash its fullest potential, the Cea has built NeuroSpin, an ultra-high-field neuroimaging facility at its Saclay centre (in the Essonne). NeuroSpin already boasts three fully operational MRI systems. The first is a 3-tesla high-field system and the second is a very-high-field 7-tesla system, both of which are dedicated to clinical studies and investigations in humans, while the third is an ultra-high-field 17.65-tesla system designed for studies on small animals. In 2011, NeuroSpin will be commissioning an 11.7-tesla ultra-high-field system of unprecedented power that is designed for research on human subjects. The level of the magnetic field and the scale required will make this joint French-German project to build the magnet a breakthrough in the international arena. (authors)

  8. Diagnostic apparatus employing nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Hoshino, K.; Yamada, N.; Yoshitome, E.; Matsuura, H.

    1987-01-01

    An NMR diagnostic apparatus is described comprising means for applying a primary magnetic field to a subject; means for applying RF pulses to the subject to give nuclear magnetic resonance to the nuclei of atoms in the subject; means for applying gradient magnetic fields to project an NMR signal of the nuclei at least in one direction; means for observing the NMR signal projected by the gradient magnetic fields applying means; and arithmetic means for constructing a distribution of information on resonance energy as an image from an output signal from the observing means; wherein the gradient magnetic fields applying means comprises means for applying the gradient magnetic fields at a predetermined time and for not applying the gradient magnetic fields at another predetermined time, during the time period of one view; and wherein the gradient magnetic fields applying means further comprises means for measuring the NMR signal during the predetermined time when the gradient magnetic fields are applied, and means for measuring the intensity of the primary magnetic field during the other predetermined time when no gradient magnetic fields are applied

  9. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... vision or seizures help detect certain chronic diseases of the nervous system, such as multiple sclerosis diagnose problems with the ... moveable examination table that slides into the center of the magnet. Some MRI units, called short-bore systems , are designed so that the magnet does not ...

  10. Embroidered Coils for Magnetic Resonance Sensors

    Directory of Open Access Journals (Sweden)

    Michael I. Newton

    2013-04-01

    Full Text Available Magnetic resonance imaging is a widely used technique for medical and materials imaging. Even though the objects being imaged are often irregularly shaped, suitable coils permitting the measurement of the radio-frequency signal in these systems are usually made of solid copper. One problem often encountered is how to ensure the coils are both in close proximity and conformal to the object being imaged. Whilst embroidered conductive threads have previously been used as antennae in mobile telecommunications applications, they have not previously been reported for use within magnetic resonance. In this paper we show that an embroidered single loop coil can be used in a commercial unilateral nuclear magnetic resonance system as an alternative to a solid copper. Data is presented showing the determination of both longitudinal (T1 and effective transverse (T2eff relaxation times for a flat fabric coil and the same coil conformed to an 8 cm diameter cylinder. We thereby demonstrate the principles required for the wider use of fabric based conformal coils within nuclear magnetic resonance and magnetic resonance imaging.

  11. Magnetic resonance arthrography in chronic wrist pain

    International Nuclear Information System (INIS)

    Valeri, G.; Ferrara, C.; Carloni, S.

    1999-01-01

    The purpose of this paper is to investigate the clinical role of Magnetic Resonance Arthrography (MRA) of the wrist in subjects with chronic pain. Thirty-five patients complaining of wrist pain for more than 6 months were submitted to MRI an MRA. All patients received and intra-articular injection of 2-10 mL of a 10 mmol saline solution of Gd-DPTA. The overall diagnostic accuracy rates of MRI and MRA were 40% and 81% respectively, with sensitivity and specificity of 63% and 39% (MRI) and of 82% and 79% (MRA). The conclusion is that compared with MRI, MRA can be considered a useful tool for the visualization of interosseus carpal ligaments and of the triangular fibrocartilage complex. MRA also helps detect injuries in these structures [it

  12. Chest magnetic resonance imaging: a protocol suggestion

    Directory of Open Access Journals (Sweden)

    Bruno Hochhegger

    2015-12-01

    Full Text Available Abstract In the recent years, with the development of ultrafast sequences, magnetic resonance imaging (MRI has been established as a valuable diagnostic modality in body imaging. Because of improvements in speed and image quality, MRI is now ready for routine clinical use also in the study of pulmonary diseases. The main advantage of MRI of the lungs is its unique combination of morphological and functional assessment in a single imaging session. In this article, the authors review most technical aspects and suggest a protocol for performing chest MRI. The authors also describe the three major clinical indications for MRI of the lungs: staging of lung tumors; evaluation of pulmonary vascular diseases; and investigation of pulmonary abnormalities in patients who should not be exposed to radiation.

  13. Magnetic resonance imaging of spinal plasmacytoma

    International Nuclear Information System (INIS)

    Shah, B.K.; Saifuddin, A.; Price, G.J.

    2000-01-01

    AIM: To describe the magnetic resonance imaging (MRI) features of spinal plasmacytoma. MATERIALS AND METHODS: The clinical records and MRI findings in six patients (five men, one woman; age range 41-61 years) with histologically proven plasmacytoma of the spine were reviewed. All studies included sagittal T1- and T2-weighted spin-echo sequences and axial T1-weighted spin-echo sequences. Intravenous gadolinium DTPA was administered in four cases. RESULTS: MRI showed a characteristic appearances in four cases of low signal intensity curvilinear areas within the vertebra or cortical irregularity. CONCLUSION: Recognition of these imaging features can initiate the appropriate investigation as the commonest differential diagnosis for such lesions is metastasis. Shah, B. K. (2000)

  14. Magnetic resonance tomography and ultrasound in rheumatology

    International Nuclear Information System (INIS)

    Kainberger, F.; Czerny, C.; Trattnig, S.; Lack, W.; Machold, K.; Graninger, W.

    1996-01-01

    Technical innovations and software improvements in magnetic resonance imaging (MRI) and high-resolution sonography (US) have definitely influenced the diagnostic imaging of rheumatic diseases. For MRI, improvements in surface coils, dedicated low-field systems (0.2 T), and software improvements (shorter acquisition times and refinements of fat suppressing techniques) must be mentioned. For sonography, the main innovations concern the development of higher transducer frequencies (7-15 Mhz) and power Doppler imaging. Clinical evaluations have shown that MRI and US are most useful in cases of suspected rheumatic disease with negative plain film radiographs and for documenting the course of the disease, diagnosing of early rheumatoid arthritis, making a differential diagnosis in clinically unclear rheumatic diseases, investigating vascularization, and quantifying pannus formation. In order to improve diagnostic efficacy the role of MRI and US in the management of patients with rheumatic disease should be reconsidered. (orig.) [de

  15. Magnetic resonance imaging of facial muscles

    Energy Technology Data Exchange (ETDEWEB)

    Farrugia, M.E. [Department of Clinical Neurology, University of Oxford, Radcliffe Infirmary, Oxford (United Kingdom)], E-mail: m.e.farrugia@doctors.org.uk; Bydder, G.M. [Department of Radiology, University of California, San Diego, CA 92103-8226 (United States); Francis, J.M.; Robson, M.D. [OCMR, Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford (United Kingdom)

    2007-11-15

    Facial and tongue muscles are commonly involved in patients with neuromuscular disorders. However, these muscles are not as easily accessible for biopsy and pathological examination as limb muscles. We have previously investigated myasthenia gravis patients with MuSK antibodies for facial and tongue muscle atrophy using different magnetic resonance imaging sequences, including ultrashort echo time techniques and image analysis tools that allowed us to obtain quantitative assessments of facial muscles. This imaging study had shown that facial muscle measurement is possible and that useful information can be obtained using a quantitative approach. In this paper we aim to review in detail the methods that we applied to our study, to enable clinicians to study these muscles within the domain of neuromuscular disease, oncological or head and neck specialties. Quantitative assessment of the facial musculature may be of value in improving the understanding of pathological processes occurring within facial muscles in certain neuromuscular disorders.

  16. Magnetic resonance imaging of facial muscles

    International Nuclear Information System (INIS)

    Farrugia, M.E.; Bydder, G.M.; Francis, J.M.; Robson, M.D.

    2007-01-01

    Facial and tongue muscles are commonly involved in patients with neuromuscular disorders. However, these muscles are not as easily accessible for biopsy and pathological examination as limb muscles. We have previously investigated myasthenia gravis patients with MuSK antibodies for facial and tongue muscle atrophy using different magnetic resonance imaging sequences, including ultrashort echo time techniques and image analysis tools that allowed us to obtain quantitative assessments of facial muscles. This imaging study had shown that facial muscle measurement is possible and that useful information can be obtained using a quantitative approach. In this paper we aim to review in detail the methods that we applied to our study, to enable clinicians to study these muscles within the domain of neuromuscular disease, oncological or head and neck specialties. Quantitative assessment of the facial musculature may be of value in improving the understanding of pathological processes occurring within facial muscles in certain neuromuscular disorders

  17. Magnetic resonance imaging of placenta accreta

    Science.gov (United States)

    Varghese, Binoj; Singh, Navdeep; George, Regi A.N; Gilvaz, Sareena

    2013-01-01

    Placenta accreta (PA) is a severe pregnancy complication which occurs when the chorionic villi (CV) invade the myometrium abnormally. Optimal management requires accurate prenatal diagnosis. Ultrasonography (USG) and magnetic resonance imaging (MRI) are the modalities for prenatal diagnosis of PA, although USG remains the primary investigation of choice. MRI is a complementary technique and reserved for further characterization when USG is inconclusive or incomplete. Breath-hold T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) and balanced steady-state free precession imaging in the three orthogonal planes is the key MRI technique. Markedly heterogeneous placenta, thick intraplacental dark bands on half-Fourier acquisition single-shot turbo spin-echo (HASTE), and disorganized abnormal intraplacental vascularity are the cardinal MRI features of PA. MRI is less reliable in differentiating between different degrees of placental invasion, especially between accreta vera and increta. PMID:24604945

  18. Magnetic resonance imaging of placenta accreta

    Directory of Open Access Journals (Sweden)

    Binoj Varghese

    2013-01-01

    Full Text Available Placenta accreta (PA is a severe pregnancy complication which occurs when the chorionic villi (CV invade the myometrium abnormally. Optimal management requires accurate prenatal diagnosis. Ultrasonography (USG and magnetic resonance imaging (MRI are the modalities for prenatal diagnosis of PA, although USG remains the primary investigation of choice. MRI is a complementary technique and reserved for further characterization when USG is inconclusive or incomplete. Breath-hold T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE and balanced steady-state free precession imaging in the three orthogonal planes is the key MRI technique. Markedly heterogeneous placenta, thick intraplacental dark bands on half-Fourier acquisition single-shot turbo spin-echo (HASTE, and disorganized abnormal intraplacental vascularity are the cardinal MRI features of PA. MRI is less reliable in differentiating between different degrees of placental invasion, especially between accreta vera and increta.

  19. Magnetic resonance imaging of placenta accreta

    International Nuclear Information System (INIS)

    Varghese, Binoj; Singh, Navdeep; George, Regi A.N; Gilvaz, Sareena

    2013-01-01

    Placenta accreta (PA) is a severe pregnancy complication which occurs when the chorionic villi (CV) invade the myometrium abnormally. Optimal management requires accurate prenatal diagnosis. Ultrasonography (USG) and magnetic resonance imaging (MRI) are the modalities for prenatal diagnosis of PA, although USG remains the primary investigation of choice. MRI is a complementary technique and reserved for further characterization when USG is inconclusive or incomplete. Breath-hold T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) and balanced steady-state free precession imaging in the three orthogonal planes is the key MRI technique. Markedly heterogeneous placenta, thick intraplacental dark bands on half-Fourier acquisition single-shot turbo spin-echo (HASTE), and disorganized abnormal intraplacental vascularity are the cardinal MRI features of PA. MRI is less reliable in differentiating between different degrees of placental invasion, especially between accreta vera and increta

  20. Functional Magnetic Resonance Imaging in Consumer Research

    DEFF Research Database (Denmark)

    Reimann, Martin; Schilke, Oliver; Weber, Bernd

    2011-01-01

    of prior fMRI research related to consumer behavior and highlights the features that make fMRI an attractive method for consumer and marketing research. The authors discuss advantages and limitations and illustrate the proposed procedures with an applied study, which investigates loss aversion when buying......Although the field of psychology is undergoing an immense shift toward the use of functional magnetic resonance imaging (fMRI), the application of this methodology to consumer research is relatively new. To assist consumer researchers in understanding fMRI, this paper elaborates on the findings...... and selling a common product. Results reveal a significantly stronger activation in the amygdala while consumers estimate selling prices versus buying prices, suggesting that loss aversion is associated with the processing of negative emotion. © 2011 Wiley Periodicals, Inc....

  1. Pharmaceutical applications of magnetic resonance imaging (MRI).

    Science.gov (United States)

    Richardson, J Craig; Bowtell, Richard W; Mäder, Karsten; Melia, Colin D

    2005-06-15

    Magnetic resonance imaging (MRI) is a powerful imaging modality that provides internal images of materials and living organisms on a microscopic and macroscopic scale. It is non-invasive and non-destructive, and one of very few techniques that can observe internal events inside undisturbed specimens in situ. It is versatile, as a wide range of NMR modalities can be accessed, and 2D and 3D imaging can be undertaken. Despite widespread use and major advances in clinical MRI, it has seen limited application in the pharmaceutical sciences. In vitro studies have focussed on drug release mechanisms in polymeric delivery systems, but isolated studies of bioadhesion, tablet properties, and extrusion and mixing processes illustrate the wider potential. Perhaps the greatest potential however, lies in investigations of pharmaceuticals in vivo, where pilot human and animal studies have demonstrated we can obtain unique insights into the behaviour of gastrointestinal, topical, colloidal, and targeted drug delivery systems.

  2. Whole-body magnetic resonance imaging in axial spondyloarthritis

    DEFF Research Database (Denmark)

    Krabbe, Simon; Østergaard, Mikkel; Eshed, Iris

    2018-01-01

    Objective. To investigate whether adalimumab (ADA) reduces whole-body (WB-) magnetic resonance imaging (MRI) indices for inflammation in the entheses, peripheral joints, sacroiliac joints, spine, and the entire body in patients with axial spondyloarthritis (axSpA). Methods. An investigator-initia...

  3. Investigating the capability to resolve complex white matter structures with high b-value diffusion magnetic resonance imaging on the MGH-USC Connectom scanner.

    Science.gov (United States)

    Fan, Qiuyun; Nummenmaa, Aapo; Witzel, Thomas; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Van Dijk, Koene R A; Buckner, Randy L; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L

    2014-11-01

    One of the major goals of the NIH Blueprint Human Connectome Project was to map and quantify the white matter connections in the brain using diffusion tractography. Given the prevalence of complex white matter structures, the capability of resolving local white matter geometries with multiple crossings in the diffusion magnetic resonance imaging (dMRI) data is critical. Increasing b-value has been suggested for delineation of the finer details of the orientation distribution function (ODF). Although increased gradient strength and duration increase sensitivity to highly restricted intra-axonal water, gradient strength limitations require longer echo times (TE) to accommodate the increased diffusion encoding times needed to achieve a higher b-value, exponentially lowering the signal-to-noise ratio of the acquisition. To mitigate this effect, the MGH-USC Connectom scanner was built with 300 mT/m gradients, which can significantly reduce the TE of high b-value diffusion imaging. Here we report comparisons performed across b-values based on q-ball ODF metrics to investigate whether high b-value diffusion imaging on the Connectom scanner can improve resolving complex white matter structures. The q-ball ODF features became sharper as the b-value increased, with increased power fraction in higher order spherical harmonic series of the ODF and increased peak heights relative to the overall size of the ODF. Crossing structures were detected in an increasingly larger fraction of white matter voxels and the spatial distribution of two-way and three-way crossing structures was largely consistent with known anatomy. Results indicate that dMRI with high diffusion encoding on the Connectom system is a promising tool to better characterize, and ultimately understand, the underlying structural organization and motifs in the human brain.

  4. Measurement of cerebral white matter perfusion using pseudocontinuous arterial spin labeling 3T magnetic resonance imaging--an experimental and theoretical investigation of feasibility.

    Directory of Open Access Journals (Sweden)

    Wen-Chau Wu

    Full Text Available PURPOSE: This study was aimed to experimentally and numerically investigate the feasibility of measuring cerebral white matter perfusion using pseudocontinuous arterial spin labeling (PCASL 3T magnetic resonance imaging (MRI at a relatively fine resolution to mitigate partial volume effect from gray matter. MATERIALS AND METHODS: The Institutional Research Ethics Committee approved this study. On a clinical 3T MR system, ten healthy volunteers (5 females, 5 males, age = 28 ± 3 years were scanned after providing written informed consent. PCASL imaging was performed with varied combinations of labeling duration (τ = 1000, 1500, 2000, and 2500 ms and post-labeling delay (PLD = 1000, 1400, 1800, and 2200 ms, at a spatial resolution (1.56 x 1.56 x 5 mm(3 finer than commonly used (3.5 x 3.5 mm(2, 5-8 mm in thickness. Computer simulations were performed to calculate the achievable perfusion-weighted signal-to-noise ratio at varied τ, PLD, and transit delay. RESULTS: Based on experimental and numerical data, the optimal τ and PLD were found to be 2000 ms and 1500-1800 ms, respectively, yielding adequate SNR (~2 to support perfusion measurement in the majority (~60% of white matter. The measurement variability was about 9% in a one-week interval. The measured white matter perfusion and perfusion ratio of gray matter to white matter were 15.8-27.5 ml/100ml/min and 1.8-4.0, respectively, depending on spatial resolution as well as the amount of deep white matter included. CONCLUSION: PCASL 3T MRI is able to measure perfusion in the majority of cerebral white matter at an adequate signal-to-noise ratio by using appropriate tagging duration and post-labeling delay. Although pixel-wise comparison may not be possible, region-of-interest based flow quantification is feasible.

  5. The Role of Magnetic Resonance Imaging in the Investigation and Management of Invasive Lobular Carcinoma-A 3-Year Retrospective Study in Two District General Hospitals.

    Science.gov (United States)

    Derias, Mina; Subramanian, Ashok; Allan, Simon; Shah, Elizabeth; Teraifi, Hassan El; Howlett, David

    2016-07-01

    Invasive lobular carcinoma (ILC) accounts for 5-15% of breast cancers. In comparison to other types of breast cancer, ILC is more likely to be associated with multifocal and contralateral breast involvement as well as a tendency to a diffuse infiltrative growth pattern which can represent a diagnostic challenge. The National Institute of Clinical Excellence guidelines in 2009 recommended the use of magnetic resonance imaging (MRI) in the preoperative assessment of ILC. This study aims to assess compliance with the guidelines in two District General Hospitals and the utility of MRI in the investigation of ILC. All cases of ILC between 2011 and 2013 were retrospectively identified from the pathology database and their breast imaging findings, pathology report, and operative intervention were reviewed. A total of 126 patients were identified with ILC, of these 46 had MRI preoperatively (36.5%). MRI upgraded mammography/ultrasound diagnoses in 10 patients (21.7%). MRI showed multicentric unilateral disease in 17 patients (37.0%) occult on ultrasound/mammogram, with these patients undergoing mastectomy and 16/17 (94.1%) confirmed multifocality on pathology. MRI showed a contralateral lesion in 9 patients (19.6%), four (8.7%) of which were malignant and had bilateral surgery, and five (10.9%) were benign on further imaging/biopsy. MRI also downgraded three patients (6.5%) to unifocal disease with reported multifocal appearances on mammography/ultrasound, and these patients underwent breast-conserving surgery. MRI adds significant additional information to mammograms/ultrasound in ILC and should be undertaken in all such cases preoperatively assuming no contraindication. © 2016 Wiley Periodicals, Inc.

  6. Resting-state functional magnetic resonance imaging investigation of the neural correlates of cognitive-behavioral therapy for externalizing behavior problems in adolescent bullies.

    Science.gov (United States)

    Kim, Johanna Inhyang; Kang, Yun-Hyong; Lee, Jong-Min; Cha, Jungho; Park, Yeong-Hun; Kweon, Kuk-Ju; Kim, Bung-Nyun

    2018-06-06

    The purpose of this study was to investigate the neural correlates of cognitive-behavioral therapy (CBT) for externalizing behavior problems in perpetrators of school bullying using assessments of brain activity and behavior. Twenty-five adolescent bullies participated in an 8-session intervention. Prior to and after participation, 24 adolescents were evaluated using the Child Behavior Checklist (CBCL) and 23 completed resting-state functional magnetic resonance imaging. Changes in the fractional amplitude of low-frequency fluctuations (fALFF) and scores on the CBCL were analyzed. We also compared the identified changes into 2 groups (low and high delinquency) differentiated by a cutoff of 65 points on the delinquency subscale of the CBCL. Following the intervention, participants exhibited improvement in the subscores of the CBCL and decreases in the fALFF of the inferior parietal lobule, lingual, interior frontal and middle occipital gyrus. A positive correlation was observed between changes in the CBCL externalizing behavior scores and fALFF of the inferior frontal gyrus. The high delinquency group showed a greater decrease in delinquency and externalizing CBCL subscores across time than did the low delinquency group. The high delinquency group had more areas that showed change in fALFF post-intervention than did the low delinquency group. A positive correlation was observed between changes in the CBCL delinquency scores and fALFF of the precentral gyrus in the high delinquency group. The results indicate that this CBT for externalizing behavior problems in bullies had more positive effects on delinquent behavior in adolescents with high levels of delinquency, and these changes were associated with functional changes in brain activity. ClinicalTrials.gov identifier: NCT02670876. Copyright © 2018. Published by Elsevier Inc.

  7. 1H and 31P nuclear magnetic resonance investigation of the interaction between 2,3-diphosphoglycerate and human normal adult hemoglobin.

    Science.gov (United States)

    Russu, I M; Wu, S S; Bupp, K A; Ho, N T; Ho, C

    1990-04-17

    High-resolution 1H and 31P nuclear magnetic resonance spectroscopy has been used to investigate the binding of 2,3-diphosphoglycerate to human normal adult hemoglobin and the molecular interactions involved in the allosteric effect of the 2,3-diphosphoglycerate molecule on hemoglobin. Individual hydrogen ion NMR titration curves have been obtained for 22-26 histidyl residues of hemoglobin and for each phosphate group of 2,3-diphosphoglycerate with hemoglobin in both the deoxy and carbonmonoxy forms. The results indicate that 2,3-diphosphoglycerate binds to deoxyhemoglobin at the central cavity between the two beta chains and the binding involves the beta 2-histidyl residues. Moreover, the results suggest that the binding site of 2,3-diphosphoglycerate to carbonmonoxyhemoglobin contains the same (or at least some of the same) amino acid residues responsible for binding in the deoxy form. As a result of the specific interactions with 2,3-diphosphoglycerate, the beta 2-histidyl residues make a significant contribution to the alkaline Bohr effect under these experimental conditions (up to 0.5 proton/Hb tetramer). 2,3-Diphosphoglycerate also affects the individual hydrogen ion equilibria of several histidyl residues located away from the binding site on the surface of the hemoglobin molecule, and, possibly, in the heme pockets. These results give the first experimental demonstration that long-range electrostatic and/or conformational effects of the binding could play an important role in the allosteric effect of 2,3-diphosphoglycerate on hemoglobin.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn; Creber, Sarah A.; Vrouwenvelder, Johannes S.; Johns, Michael L.

    2015-01-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.

  9. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn

    2015-03-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth\\'s magnetic field system.

  10. Generation of nuclear magnetic resonance images

    International Nuclear Information System (INIS)

    Beckmann, N.X.

    1986-01-01

    Two generation techniques of nuclear magnetic resonance images, the retro-projection and the direct transformation method are studied these techniques are based on the acquisition of NMR signals which phases and frequency components are codified in space by application of magnetic field gradients. The construction of magnet coils is discussed, in particular a suitable magnet geometry with polar pieces and air gap. The obtention of image contrast by T1 and T2 relaxation times reconstructed from generated signals using sequences such as spin-echo, inversion-recovery and stimulated echo, is discussed. The mathematical formalism of matrix solution for Bloch equations is also presented. (M.C.K.)

  11. Susceptibility effects in nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ziener, Christian Herbert

    2008-01-01

    The properties of dephasing and the resulting relaxation of the magnetization are the basic principle on which all magnetic resonance imaging methods are based. The signal obtained from the gyrating spins is essentially determined by the properties of the considered tissue. Especially the susceptibility differences caused by magnetized materials (for example, deoxygenated blood, BOLD-effect) or magnetic nanoparticles are becoming more important for biomedical imaging. In the present work, the influence of such field inhomogeneities on the NMR-signal is analyzed. (orig.)

  12. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... a risk, depending on their nature and the strength of the MRI magnet. Many implanted devices will ... full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy ...

  13. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... a risk, depending on their nature and the strength of the MRI magnet. Many implanted devices will ... full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy ...

  14. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... and extremities. Tell your doctor about your child’s health problems, medications, recent surgeries and allergies. The magnetic ... the radiologist if your child has any serious health problems or has recently had surgery. Some conditions, ...

  15. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... doctor about your child’s health problems, medications, recent surgeries and allergies. The magnetic field is not harmful, ... to the heart muscle evaluate findings following cardiovascular surgery In the abdominal and pelvic region, MRI is ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... material called gadolinium, which is less likely to cause an allergic reaction than iodinated contrast material. Tell ... magnetic field is not harmful, but it may cause some medical devices to malfunction. Most orthopedic implants ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... distort images of the facial area or brain, so you should let the radiologist know about them. ... MRI units, called short-bore systems , are designed so that the magnet does not completely surround you. ...

  18. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... distort images of the facial area or brain, so the radiologist should be aware of them. Parents ... MRI units, called short-bore systems , are designed so that the magnet does not completely surround you. ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... x-ray contrast material, drugs, food, or the environment, or if you have asthma. The contrast material ... are also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or ...

  20. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... x-ray contrast material, drugs, food, or the environment, or if your child has asthma. The contrast ... are also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or ...

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... interfere with the magnetic field of the MRI unit, metal and electronic items are not allowed in ... the MRI equipment look like? The traditional MRI unit is a large cylinder-shaped tube surrounded by ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... interfere with the magnetic field of the MRI unit, metal and electronic items are not allowed in ... does the equipment look like? The traditional MRI unit is a large cylinder-shaped tube surrounded by ...

  3. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... an MRI scan, but this is rare. Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so you should let the ...

  4. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... lodged in the eyes are particularly important. Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so the radiologist should be ...

  5. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... traditional MRI unit is a large cylinder-shaped tube surrounded by a circular magnet. You will lie ... your skin at the site of the IV tube insertion. Some patients may sense a temporary metallic ...

  6. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... traditional MRI unit is a large cylinder-shaped tube surrounded by a circular magnet. Your child will ... skin irritation at the site of the IV tube insertion. Some patients may sense a temporary metallic ...

  7. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures ... may follow your regular daily routine and take food and medications as usual. Some MRI examinations may ...

  8. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures ... regular daily routine and have him/her take food and medications as usual. Some MRI examinations may ...

  9. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  10. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... if your child has any implanted medical or electronic devices. Inform your doctor and the technologist prior ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ...

  11. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... The magnetic field is produced by passing an electric current through wire coils in most MRI units. ... signals that are detected by the coils. The electric current does not come in contact with the ...

  12. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... The magnetic field is produced by passing an electric current through wire coils in most MRI units. ... signals that are detected by the coils. The electric current does not come in contact with the ...

  13. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Magnetic ...

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... pregnant. The magnetic field is not harmful, but it may cause some medical devices to malfunction. Most ... number of abrupt onset or long-standing symptoms. It can help diagnose conditions such as: brain tumors ...

  15. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... allergies. The magnetic field is not harmful, but it may cause some medical devices to malfunction. Most ... cord is needed, MRI is useful because of its ability to see through the skull and the ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... about pregnancy and MRI. If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want ... also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or headphones ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or headphones ... have special pediatric considerations. The teddy bear denotes child-specific content. Related Articles and Media MR Angiography ( ...

  18. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... allergies and whether there’s a possibility you are pregnant. The magnetic field is not harmful, but it ... if there is any possibility that they are pregnant. MRI has been used for scanning patients since ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI) procedure View full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Related Articles and Media MR Angiography (MRA) Magnetic ...

  20. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... The magnetic field is produced by passing an electric current through wire coils in most MRI units. Other coils, located in the machine and in some cases, placed around the part ...

  1. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... The magnetic field is produced by passing an electric current through wire coils in most MRI units. Other coils, located in the machine and in some cases, placed around the part ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... fluid spaces within the brain (ventricles) causes of epilepsy (seizure) hemorrhage in selected trauma patients certain chronic ... also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or headphones ...

  3. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... two-way intercom. Many MRI centers allow a parent to stay in the room as long as they are also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or headphones ...

  4. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... your child’s health problems, medications, recent surgeries and allergies. The magnetic field is not harmful, but it ... the exam if your child has a known allergy to contrast material. Your child should wear loose, ...

  5. Magnetic resonance imaging of breast implants.

    Science.gov (United States)

    Shah, Mala; Tanna, Neil; Margolies, Laurie

    2014-12-01

    Silicone breast implants have significantly evolved since their introduction half a century ago, yet implant rupture remains a common and expected complication, especially in patients with earlier-generation implants. Magnetic resonance imaging is the primary modality for assessing the integrity of silicone implants and has excellent sensitivity and specificity, and the Food and Drug Administration currently recommends periodic magnetic resonance imaging screening for silent silicone breast implant rupture. Familiarity with the types of silicone implants and potential complications is essential for the radiologist. Signs of intracapsular rupture include the noose, droplet, subcapsular line, and linguine signs. Signs of extracapsular rupture include herniation of silicone with a capsular defect and extruded silicone material. Specific sequences including water and silicone suppression are essential for distinguishing rupture from other pathologies and artifacts. Magnetic resonance imaging provides valuable information about the integrity of silicone implants and associated complications.

  6. Magnetic resonance enterography in pediatric celiac disease.

    Science.gov (United States)

    Koc, Gonca; Doganay, Selim; Sevinc, Eylem; Deniz, Kemal; Chavhan, Govind; Gorkem, Sureyya B; Karacabey, Neslihan; Dogan, Mehmet S; Coskun, Abdulhakim; Aslan, Duran

    To assess if magnetic resonance enterography is capable of showing evidence/extent of disease in pediatric patients with biopsy-proven celiac disease by comparing with a control group, and to correlate the magnetic resonance enterography findings with anti-endomysial antibody level, which is an indicator of gluten-free dietary compliance. Thirty-one pediatric patients (mean age 11.7±3.1 years) with biopsy-proven celiac disease and 40 pediatric patients as a control group were recruited in the study. The magnetic resonance enterography images of both patients with celiac disease and those of the control group were evaluated by two pediatric radiologists in a blinded manner for the mucosal pattern, presence of wall thickening, luminal distention of the small bowel, and extra-intestinal findings. Patient charts were reviewed to note clinical features and laboratory findings. The histopathologic review of the duodenal biopsies was re-conducted. The mean duration of the disease was 5.6±1.8 years (range: 3-7.2 years). In 24 (77%) of the patients, anti-endomysial antibody levels were elevated (mean 119.2±66.6RU/mL). Magnetic resonance enterography revealed normal fold pattern in all the patients. Ten (32%) patients had enlarged mesenteric lymph nodes. Although a majority of the patients had elevated anti-endomysial antibody levels indicating poor dietary compliance, magnetic resonance enterography did not show any mucosal abnormality associated with the inability of magnetic resonance enterography to detect mild/early changes of celiac disease in children. Therefore, it may not be useful for the follow-up of pediatric celiac disease. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  7. Magnetic resonance imaging of popliteal artery pathologies

    International Nuclear Information System (INIS)

    Holden, Andrew; Merrilees, Stephen; Mitchell, Nicola; Hill, Andrew

    2008-01-01

    This paper illustrates examples of popliteal artery pathologies imaged with contrast enhanced magnetic resonance angiography (CE-MRA) and magnetic resonance imaging (MRI) at a single tertiary referral centre. Popliteal artery pathologies were identified in 1710 patients referred over a 6-year period with symptoms suggesting lower limb arterial occlusive disease. Common pathologies such as atherosclerotic occlusive disease, thromboemboli and aneurysm disease are discussed as well as unusual pathologies such as cystic adventitial disease, mycotic aneurysm and arterial entrapment. The combination of CE-MRA and the excellent soft tissue resolution of MRI allow detailed evaluation of arterial and peri-arterial pathologies, and facilitate appropriate management decisions

  8. Magnetic resonance imaging of popliteal artery pathologies

    Energy Technology Data Exchange (ETDEWEB)

    Holden, Andrew [Department of Radiology, Auckland City Hospital, Park Road, Grafton, Auckland 9 (New Zealand)], E-mail: andrewh@adhb.govt.nz; Merrilees, Stephen [Department of Radiology, Auckland City Hospital, Park Road, Grafton, Auckland 9 (New Zealand)], E-mail: smerrilees@adhb.govt.nz; Mitchell, Nicola [Department of Radiology, Auckland City Hospital, Park Road, Grafton, Auckland 9 (New Zealand)], E-mail: nmit010@ec.auckland.ac.nz; Hill, Andrew [Department of Vascular Surgery, Auckland City Hospital, Park Road, Grafton, Auckland 9 (New Zealand)], E-mail: ahill@adhb.govt.nz

    2008-07-15

    This paper illustrates examples of popliteal artery pathologies imaged with contrast enhanced magnetic resonance angiography (CE-MRA) and magnetic resonance imaging (MRI) at a single tertiary referral centre. Popliteal artery pathologies were identified in 1710 patients referred over a 6-year period with symptoms suggesting lower limb arterial occlusive disease. Common pathologies such as atherosclerotic occlusive disease, thromboemboli and aneurysm disease are discussed as well as unusual pathologies such as cystic adventitial disease, mycotic aneurysm and arterial entrapment. The combination of CE-MRA and the excellent soft tissue resolution of MRI allow detailed evaluation of arterial and peri-arterial pathologies, and facilitate appropriate management decisions.

  9. Magnetic resonance imaging of intramuscular metastases

    International Nuclear Information System (INIS)

    Surov, Alexey; Spielmann, Rolf-Peter; Behrmann, Curd; Fiedler, Eckhard; Voigt, Wieland; Wienke, Andreas; Holzhausen, Hans-Juergen

    2011-01-01

    The aim of the present study was to analyse magnetic resonance findings of intramuscular metastases (IM) in a relatively large series. From January 2000 to January 2010, 28 patients (207 metastases) were retrospectively identified in the radiological database of the Martin-Luther-University. Several different scanning protocols were used depending on the localisation of IM. In 12 patients diffusion-weighted (DW) images were obtained with a multi-shot SE-EPI sequence. Apparent diffusion coefficient (ADC) maps were also calculated. Furthermore, fusion images were manually generated between the DW and half-Fourier acquisition single-shot turbo spin echo (HASTE) images. On T2-weighted images, 97% of the recognised IM were hyperintense in comparison to unaffected musculature, and 3% were mixed iso- to hyperintense. On T1-weighted images most IM (91%) were homogeneously isointense in comparison to muscle tissue, whereas 4% were hypointense, and 5% lightly hyperintense. ADC maps were calculated for 91 metastases ranging from 0.99 to 4.00 mm 2 s -1 (mean value 1.99 ± 0.66). ADC values of low ( 3.0) in 6%. Of the IM that were investigated with contrast medium, 88.5% showed marked enhancement. It was homogeneous in 88% and heterogenous in 6%. Rim enhancement with central low attenuation was seen in 6%. There was no difference in enhancement characteristics with respect to ADC values or fusion patterns. Peritumoral enhancement was identified in 2.4%. Magnetic resonance features of muscle metastases are relatively typical and consist of round or oval intramuscular masses with well-defined margins, marked enhancement, low or moderate ADC values, and moderate to high signal intensity on fusion images. (orig.)

  10. Non-resonant magnetic braking on JET and TEXTOR

    DEFF Research Database (Denmark)

    Sun, Y.; Liang, Y.; Shaing, K.C.

    2012-01-01

    The non-resonant magnetic braking effect induced by a non-axisymmetric magnetic perturbation is investigated on JET and TEXTOR. The collisionality dependence of the torque induced by the n = 1, where n is the toroidal mode number, magnetic perturbation generated by the error field correction coils...... in the 1/ν regime. The strongest NTV torque on JET is also located near the plasma core. The magnitude of the NTV torque strongly depends on the plasma response, which is also discussed in this paper. There is no obvious braking effect with n = 2 magnetic perturbation generated by the dynamic ergodic...

  11. Magnetic elliptical polarization of Schumann resonances

    International Nuclear Information System (INIS)

    Sentman, D.D.

    1987-01-01

    Measurements of orthogonal, horizontal components of the magnetic field in the ELF range obtained during September 1985 show that the Schumann resonance eigenfrequencies determined separately for the north-south and east-west magnetic components differ by as much as 0.5 Hz, suggesting that the underlying magnetic signal is not linearly polarized at such times. The high degree of magnetic ellipticity found suggests that the side multiplets of the Schumann resonances corresponding to azimuthally inhomogeneous normal modes are strongly excited in the highly asymmetric earth-ionosphere cavity. The dominant sense of polarization over the measurement passband is found to be right-handed during local daylight hours, and to be left-handed during local nighttime hours. 16 references

  12. Proton magnetic resonance spectroscopy and perfusion magnetic resonance imaging in the evaluation of musculoskeletal tumors

    International Nuclear Information System (INIS)

    Costa, Flavia Martins; Setti, Marcela; Vianna, Evandro Miguelote; Domingues, Romulo Cortes; Meohas, Walter; Rezende, Jose Francisco; Gasparetto, Emerson Leandro

    2009-01-01

    Objective: To assess the role of proton magnetic resonance spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in the differentiation between malignant and benign musculoskeletal tumors. Materials And Methods: Fifty-five patients with musculoskeletal tumors (27 malignant and 28 benign) were studied. The examinations were performed in a 1.5 T magnetic resonance scanner with standard protocol, and single voxel proton magnetic resonance spectroscopy with 135 msec echo time. The dynamic contrast study was performed using T1-weighted gradient-echo sequence after intravenous gadolinium injection. Time signal intensity curves and slope values were calculated. The statistical analysis was performed with the Levene's test, followed by a Student's t-test, besides the Pearson's chi-squared and Fischer's exact tests. Results: Proton magnetic resonance spectroscopy sensitivity, specificity and accuracy were, respectively, 87.5%, 92.3% and 90.9% (p < 0.0001). Statistically significant difference was observed in the slope (%/min) between benign (mean, 27.5%/min) and malignant (mean, 110.9%/min) lesions (p < 0.0001). Conclusion: The time-intensity curve and slope values using dynamic-enhanced perfusion magnetic resonance imaging in association with the presence of choline peak demonstrated by single voxel magnetic resonance spectroscopy study are useful in the differentiation between malignant and benign musculoskeletal tumors. (author)

  13. Magnetic resonance of field-frozen and zero-field-frozen magnetic fluids

    International Nuclear Information System (INIS)

    Pereira, A.R.; Pelegrini, F.; Neto, K. Skeff; Buske, N.; Morais, P.C.

    2004-01-01

    In this study magnetic resonance was used to investigate magnetic fluid samples frozen under zero and non-zero (15 kG) external fields. The magnetite-based sample containing 2x10 17 particle/cm 3 was investigated from 100 to 400 K. Analysis of the temperature dependence of the resonance field revealed bigger magnetic structures in the frozen state than in the liquid phase. Also, differences in the mesoscopic organization in the frozen state may explain the data obtained from samples frozen under zero and non-zero fields

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... ill effects on pregnant women or their unborn babies. However, because the unborn baby will be in a strong magnetic field, pregnant ... intravenous contrast indicate mothers should not breastfeed their babies for 24-48 hours after contrast medium is ...

  15. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... epilepsy (seizure) hemorrhage in selected trauma patients certain chronic conditions, such as multiple sclerosis disorders of the ... a very small chance of irritation of your skin at the site of the IV tube insertion. Some ... Images related to Magnetic ...

  16. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic ... patient to have an allergy to a gadolinium-based contrast agent used for MRI than the iodine- ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... also screened for safety in the magnetic environment. Children will be given appropriately sized earplugs or headphones during the exam. MRI scanners are air-conditioned and well-lit. Music may be played through the headphones to help ...

  18. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... which they come. The MR scanner captures this energy and creates a picture of the tissues scanned based on this information. The magnetic field is produced by passing an electric current through wire coils in most MRI units. ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... which they come. The MR scanner captures this energy and creates a picture of the tissues scanned based on this information. The magnetic field is produced by passing an electric current through wire coils in most MRI units. ...

  20. Nuclear magnetic resonance (NMR) tomography

    International Nuclear Information System (INIS)

    Skalpe, I.O.

    1984-01-01

    A brief survey of the working principle of the NMR technique in diagnostical medicine is given. Its clinical usefulness for locating tumors, diagnosing various other diseases, such as some mental illnesses and multiple sclerosis, and its possibilities for studying biochemical processes in vivo are mentioned. The price of NMR image scanners and the problems of the strong magnetic field around the machines are mentioned

  1. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us ... MRI equipment look like? How does the procedure work? How is the ... use to diagnose medical conditions. MRI uses a powerful magnetic field, radio frequency ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us ... the equipment look like? How does the procedure work? How is the ... use to diagnose medical conditions. MRI uses a powerful magnetic field, radio frequency ...

  3. Children's (Pediatric) Magnetic Resonance Imaging

    Medline Plus

    Full Text Available ... to see, hear and speak with your child at all times using a two-way intercom. Many MRI centers allow a parent to stay in the room as long as they are also screened for safety in the magnetic environment. Children will be given ...

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... able to see, hear and speak with you at all times using a two-way intercom. Many MRI centers allow a friend or parent to stay in the room as long as they are also screened for safety in the magnetic environment. Children will be given ...

  5. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the head uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of the brain and other cranial structures that are clearer and more detailed than other imaging methods. This exam does not use ionizing radiation and may require an injection of a ...

  6. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    [5] Zhenyue Hong, “DC-voltage link resonant inverters”, Department of Electrical and. Electronic Engineering University of. Canterbury, New Zealand. [6] Kalyan Kumar Halder, Naruttam Kumar Roy and B.C. Ghosh, “Position Sensorless. Control for an Interior Permanent Magnet. Synchronous Motor SVM Drive with ANN.

  7. Magnetic resonance imaging in radiotherapy treatment planning

    NARCIS (Netherlands)

    Moerland, Marinus Adriaan

    1996-01-01

    From its inception in the early 1970's up to the present, magnetic resonance imaging (MRI) has evolved into a sophisticated technique, which has aroused considerable interest in var- ious subelds of medicine including radiotherapy. MRI is capable of imaging in any plane and does not use ionizing

  8. Pharyngeal branchial cyst: magnetic resonance findings

    Energy Technology Data Exchange (ETDEWEB)

    Cerezal, L.; Canga, A. [Department of Radiology of the ' Santa Cruz' Hospital Liencres, Cantabria (Spain); Morales, C. [Department of Otorhinolaryngology of the ' Sierrallana' Hospital Torrelavega, Cantabria (Spain); Abascal, F.; Usamentiaga, E.; Bustamante, M. [Department of Radiology of the University Hospital ' Marques de Valdecilla' , Av. de Valdecilla s/n Santander 39008 (Spain); Olcinas, O. [Department of Pathology of the University Hospital ' Marques de Valdecilla' , Av. de Valdecilla s/n Santander 39008 (Spain)

    1998-11-01

    An unusual case of pharyngeal cyst in a 25-year-old man studied by Magnetic Resonance (MR) is described. Anatomic location and pathological findings indicated the second branchial pouch origin. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  9. Pharyngeal branchial cyst: magnetic resonance findings

    International Nuclear Information System (INIS)

    Cerezal, L.; Canga, A.; Morales, C.; Abascal, F.; Usamentiaga, E.; Bustamante, M.; Olcinas, O.

    1998-01-01

    An unusual case of pharyngeal cyst in a 25-year-old man studied by Magnetic Resonance (MR) is described. Anatomic location and pathological findings indicated the second branchial pouch origin. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Numerical methods in electron magnetic resonance

    International Nuclear Information System (INIS)

    Soernes, A.R.

    1998-01-01

    The focal point of the thesis is the development and use of numerical methods in the analysis, simulation and interpretation of Electron Magnetic Resonance experiments on free radicals in solids to uncover the structure, the dynamics and the environment of the system

  11. Numerical methods in electron magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Soernes, A.R

    1998-07-01

    The focal point of the thesis is the development and use of numerical methods in the analysis, simulation and interpretation of Electron Magnetic Resonance experiments on free radicals in solids to uncover the structure, the dynamics and the environment of the system.

  12. Magnetic resonance angiography in meningovascular syphilis

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, J [Servicio de Neurologia, Hospital de Navarra and Pamplona Univ. Hospital (Spain); Soriano, G [Servicio de Neurologia, Hospital de Navarra and Pamplona Univ. Hospital (Spain); Zubieta, J L [Servicio de Neuroradiologia, Hospital de Navarra and Pamplona Univ. Hospital (Spain); Delgado, G [Servicio de Neurologia, Hospital de Navarra and Pamplona Univ. Hospital (Spain); Villanueva, J A [Servicio de Neurologia, Hospital de Navarra and Pamplona Univ. Hospital (Spain)

    1994-04-01

    Meningovascular neurosyphilis (MN) is an unusual cause of stroke in young adults. The clinical manifestations include prodromal symptoms weeks or months before definitive stroke. The diagnosis is based on clinical findings and examination of the serum and cerebrospinal fluid. We report a case of MN with basilar artery irregularities demonstrated by magnetic resonance angiography. (orig.)

  13. Cryogenic Preamplifiers for Magnetic Resonance Imaging

    DEFF Research Database (Denmark)

    Johansen, Daniel H.; Sanchez-Heredia, Juan D.; Petersen, Jan R.

    2018-01-01

    Pursuing the ultimate limit of detection in magnetic resonance imaging (MRI) requires cryogenics to decrease the thermal noise of the electronic circuits. As cryogenic coils for MRI are slowly emerging cryogenic preamplifiers are required to fully exploit their potential. A cryogenic preamplifier...

  14. Automated Segmentation of Cardiac Magnetic Resonance Images

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Nilsson, Jens Chr.; Grønning, Bjørn A.

    2001-01-01

    Magnetic resonance imaging (MRI) has been shown to be an accurate and precise technique to assess cardiac volumes and function in a non-invasive manner and is generally considered to be the current gold-standard for cardiac imaging [1]. Measurement of ventricular volumes, muscle mass and function...

  15. Magnetic resonance imaging of xanthomatous meningioma

    International Nuclear Information System (INIS)

    Katayama, Y.; Tsubokawa, T.; Tanaka, A.; Koshinaga, M.; Nemoto, N.

    1993-01-01

    A case of meningioma with extensive xanthomatous metaplasia occurring in the left frontal convexity of a 37-year-old woman is reported. The tumour was demonstrated as a hypodense mass with minimal enhancement on CT. Our findings suggest that magnetic resonance imaging may provide a clue to the diagnosis of meningiomas with extensive xanthomatous metaplasia when CT is less specific. (orig.)

  16. Evaluation of nuclear magnetic resonance spectroscopy variability

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Felipe Rodrigues; Salmon, Carlos Ernesto Garrido, E-mail: garrido@ffclrp.usp.br [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Filisofia, Ciencias e Letras; Otaduy, Maria Concepcion Garcia [Universidade de Sao Paulo (FAMUS/USP), Sao Paulo, SP (Brazil). Fac. de Medicina. Departamento de Radiologia

    2014-11-01

    Introduction: the intrinsically high sensitivity of Magnetic Resonance Spectroscopy (MRS) causes considerable variability in metabolite quantification. In this study, we evaluated the variability of MRS in two research centers using the same model of magnetic resonance image scanner. Methods: two metabolic phantoms were created to simulate magnetic resonance spectra from in vivo hippocampus. The phantoms were filled with the same basic solution containing the following metabolites: N-acetyl-aspartate, creatine, choline, glutamate, glutamine and inositol. Spectra were acquired over 15 months on 26 acquisition dates, resulting in a total of 130 spectra per center. Results: the phantoms did not undergo any physical changes during the 15-month period. Temporal analysis from both centers showed mean metabolic variations of 3.7% in acquisitions on the same day and of 8.7% over the 15-month period. Conclusion: The low deviations demonstrated here, combined with the high specificity of Magnetic Resonance Spectroscopy, confirm that it is feasible to use this technique in multicenter studies in neuroscience research. (author)

  17. Vascular anatomy in angiography for magnetic resonance

    International Nuclear Information System (INIS)

    Charry Lopez, Marco Luciano; Rivera Gomez, Juan Enrique

    1998-01-01

    A review of basic anatomical concepts and main variants, as well as some anatomical anomalies of the central nervous system vascularity, these concepts are considered essential for the interpretation of magnetic resonance angiography with time-of-flight (TOF) and phase-contrast (PC) methods

  18. Magnetic resonance imaging in obstetric diagnosis.

    Science.gov (United States)

    Weinreb, J C; Lowe, T W; Santos-Ramos, R; Cunningham, F G; Parkey, R

    1985-01-01

    Five patients with abnormal pregnancies were examined with ultrasound (US) and magnetic resonance imaging (MR). Three had a malformed fetus, 1 had a molar pregnancy, and 1 had an ovarian mass. Both maternal and fetal structures were clearly shown, although fetal motion may have resulted in image degradation in some cases. The authors suggest that MR may be useful in obstetric diagnosis.

  19. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... talk with you about magnetic resonance angiography, or as it’s commonly known, MRA. MRA is a noninvasive ... possibility that you’re pregnant tell your doctor as well. On the day of your exam, it’s ...

  20. Magnetic resonance studies of solid polymers

    International Nuclear Information System (INIS)

    Lenk, R.

    1969-01-01

    This paper is a review of the application of nuclear magnetic resonance (NMR) to solid polymers. In the first, theoretical part, the elements of the theory of NMR, which are necessary for the study of the properties of solid polymers are discussed: the moments method, nuclear relaxation and the distribution of correlation times. In the second part the experimental results are presented. (author) [fr

  1. Appropriateness of computed tomography and magnetic resonance ...

    African Journals Online (AJOL)

    Introduction. Computed tomography (CT) and magnetic resonance imaging (MRI) are an essential part of modern healthcare. Marked increases in clinical demand for these imaging modalities are straining healthcare expenditure and threatening health system sustainability. The number of CT and MRI scans requested in ...

  2. Magnetic resonance imaging of the knee

    International Nuclear Information System (INIS)

    Nederveen, D.; Bakker, C.J.G.; Scholten, F.G.; Feldberg, N.A.M.; Postma, J.H.; Vis, H. van der

    1989-01-01

    Sixteen patients suspected of having meniscal lesions, were examined bt magnetic resonance (MR) and arthroscopy, MR and arthroscopy corelate well for meniscal and cruciate ligament lesions. Damage of the articular cartilage was, however, not detected by MR (author). 15 refs.; 4 figs.; 1 tab

  3. Intralabyrinthine schwannoma shown by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Saeed, S.R.; Birzgalis, A.R.; Ramsden, R.T.

    1994-01-01

    Intralabyrinthine schwannomas are rare benign tumours which present with progressive or fluctuant audiovestibular symptoms and may mimic Menieres disease. The size and position of these lesions make preoperative diagnosis unusual and most are discovered incidentally at labyrinthectomy. A case is reported which was diagnosed on magnetic resonance imaging and confirmed at surgery. (orig.)

  4. Quantitative dosing by nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Solomon, I.

    1958-01-01

    The measurement of the absolute concentration of a heavy water reference containing approximately 99.8 per cent of D 2 O has been performed, by an original magnetic resonance method ('Adiabatic fast passage method') with a precision of 5.10 -5 on the D 2 O concentration. (author) [fr

  5. Magnetic resonance angiography in meningovascular syphilis

    International Nuclear Information System (INIS)

    Gallego, J.; Soriano, G.; Zubieta, J.L.; Delgado, G.; Villanueva, J.A.

    1994-01-01

    Meningovascular neurosyphilis (MN) is an unusual cause of stroke in young adults. The clinical manifestations include prodromal symptoms weeks or months before definitive stroke. The diagnosis is based on clinical findings and examination of the serum and cerebrospinal fluid. We report a case of MN with basilar artery irregularities demonstrated by magnetic resonance angiography. (orig.)

  6. Interaction of magnetic resonators studied by the magnetic field enhancement

    Directory of Open Access Journals (Sweden)

    Yumin Hou

    2013-12-01

    Full Text Available It is the first time that the magnetic field enhancement (MFE is used to study the interaction of magnetic resonators (MRs, which is more sensitive than previous parameters–shift and damping of resonance frequency. To avoid the coherence of lattice and the effect of Bloch wave, the interaction is simulated between two MRs with same primary phase when the distance is changed in the range of several resonance wavelengths, which is also compared with periodic structure. The calculated MFE oscillating and decaying with distance with the period equal to resonance wavelength directly shows the retardation effect. Simulation also shows that the interaction at normal incidence is sensitive to the phase correlation which is related with retardation effect and is ultra-long-distance interaction when the two MRs are strongly localized. When the distance is very short, the amplitude of magnetic resonance is oppressed by the strong interaction and thus the MFE can be much lower than that of single MR. This study provides the design rules of metamaterials for engineering resonant properties of MRs.

  7. Three-Dimensional Magnetic Resonance Imaging of Velopharyngeal Structures

    Science.gov (United States)

    Bae, Youkyung; Kuehn, David P.; Sutton, Bradley P.; Conway, Charles A.; Perry, Jamie L.

    2011-01-01

    Purpose: To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations. Method: Ten Caucasian…

  8. Resonances of the helium atom in a strong magnetic field

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Al-Hujaj, Omar-Alexander; Schmelcher, Peter

    2007-01-01

    We present an investigation of the resonances of a doubly excited helium atom in a strong magnetic field covering the regime B=0–100  a.u. A full-interaction approach which is based on an anisotropic Gaussian basis set of one-particle functions being nonlinearly optimized for each field strength...

  9. Static fluid magnetic resonance urography in evaluation of ureteral ...

    African Journals Online (AJOL)

    Introduction: Ectopic ureters are often very difficult to diagnose with conventional imaging modalities especially in children. Magnetic resonance urography (MRU) has been recently investigated as a problem-solving tool for the evaluation of various congenital urogenital anomalies with favorable results. Aim of the work: To ...

  10. The role of Magnetic Resonance Imaging and Visual Evoked ...

    African Journals Online (AJOL)

    Introduction: To report our experience in management of patients with optic neuritis. The effects of brain magnetic resonance imaging and visual evoked potential on management were investigated. Methods: This is a four years clinical trial that included patients presenting with first attack of optic neuritis older than 16 years ...

  11. Magnetic resonance study of maghemite-based magnetic fluid

    International Nuclear Information System (INIS)

    Figueiredo, L.C.; Lacava, B.M.; Skeff Neto, K.; Pelegrini, F.; Morais, P.C.

    2008-01-01

    This study reports on the magnetic resonance (MR) data (X-band experiment) of 10.2 nm average diameter maghemite nanoparticle in the temperature range of 100-230 K. Maghemite nanoparticles were suspended as low-pH ionic magnetic fluid containing 2.3x10 17 particles/cm 3 . The temperature dependence of both resonance linewidth and resonance field of the zero-field-cooled sample as well as the resonance field of the field-cooled sample (angular variation experiment) was analyzed using well-established methodology. Information regarding particle size, particle clusterization and surface magnetic anisotropy were obtained from the analysis of the MR data. The number of magnetic sites per particle from the MR data is in excellent agreement with the number provided by the transmission electron microscopy (TEM) data. The demagnetizing field value obtained from the MR data indicates cluster of particles containing on average 1.42 particles. The MR angular variation data suggest that magnetoelastic effect accounts for the non-linearity observed for the surface component of the magnetic anisotropy

  12. Magnetic resonance imaging of infectious myositis

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Ji Young; Kim, Jee Young; Kim, Sang Heum; Jung, Youn Ju; Cha, Eun Suk; Park, Joung Mi; Park, Young Ha [The Catholic Univ., College of Medicine, Suwon (Korea, Republic of)

    1998-09-01

    To describe the findings of magnetic resonance imaging in infectious myositis and to determine their value for differentiation between ruberculous and bacterial myositis. Magnetic resonance images of ten proven cases of infectious myositis (five tuberculous and five bacterial) were retrospectively reviewed in the light of clinical and laboratory findings. On the basis of magnetic resonance images, signal intensity of the mass, the presence or absence of an abscess, signal intensity of the peripheral wall, patterns of contrast enhancement, and associated findings were evaluated. Compared with those of bacterial myositis, the symptoms of tuberculous myositis lasted longer but there were no difinite local inflammatory signs. In three of five cases of bacterial myositis there were specific medical records;trauma in two cases and systemic lupus erythematosus in one. All tuberculous myositis cases involved a single muscle, but bacterial myositis affected multipe muscles in three cases(60%). All but one case showed a mass in the involved muscles. In one bacterial case, there was diffuse swelling in the involved muscle. On T1-weighted images, eight infectious cases showed low signal intensity;two, of the bactrerial type, showed subtle increased signal intensity. all cases demonstrated high signal intensity on t2-weighted images. The signal intensity of peripheral wall was slightly increased on T1-weighted images, but low on T2-weighted. In four cases there was associated cellulitis, and in one case each, adjacent joint effusion and deep vein thrombosis were seen. After gadolinium infusion, peripheral rim enhancement was noted in nine cases and heterogeneous enhancement in one. After magnetic resonance imaging of infectious myositis, the characteristic finding was an abscessed lesion, with the peripheral wall showing high signal intensity on T1-weighted images and low signal intensity on T2 weighted. Although we found it difficult to differentiate bacterial from tuberculous

  13. Magnetic resonance imaging of infectious myositis

    International Nuclear Information System (INIS)

    Yun, Ji Young; Kim, Jee Young; Kim, Sang Heum; Jung, Youn Ju; Cha, Eun Suk; Park, Joung Mi; Park, Young Ha

    1998-01-01

    To describe the findings of magnetic resonance imaging in infectious myositis and to determine their value for differentiation between ruberculous and bacterial myositis. Magnetic resonance images of ten proven cases of infectious myositis (five tuberculous and five bacterial) were retrospectively reviewed in the light of clinical and laboratory findings. On the basis of magnetic resonance images, signal intensity of the mass, the presence or absence of an abscess, signal intensity of the peripheral wall, patterns of contrast enhancement, and associated findings were evaluated. Compared with those of bacterial myositis, the symptoms of tuberculous myositis lasted longer but there were no difinite local inflammatory signs. In three of five cases of bacterial myositis there were specific medical records;trauma in two cases and systemic lupus erythematosus in one. All tuberculous myositis cases involved a single muscle, but bacterial myositis affected multipe muscles in three cases(60%). All but one case showed a mass in the involved muscles. In one bacterial case, there was diffuse swelling in the involved muscle. On T1-weighted images, eight infectious cases showed low signal intensity;two, of the bactrerial type, showed subtle increased signal intensity. all cases demonstrated high signal intensity on t2-weighted images. The signal intensity of peripheral wall was slightly increased on T1-weighted images, but low on T2-weighted. In four cases there was associated cellulitis, and in one case each, adjacent joint effusion and deep vein thrombosis were seen. After gadolinium infusion, peripheral rim enhancement was noted in nine cases and heterogeneous enhancement in one. After magnetic resonance imaging of infectious myositis, the characteristic finding was an abscessed lesion, with the peripheral wall showing high signal intensity on T1-weighted images and low signal intensity on T2 weighted. Although we found it difficult to differentiate bacterial from tuberculous

  14. Magnetic resonance imaging of aneurysmal subarachnoid hemorrhage

    International Nuclear Information System (INIS)

    Ogawa, Toshihide; Shimosegawa, Eku; Inugami, Atsushi; Shishido, Fumio; Fujita, Hideaki; Ito, Hiroshi; Uemura, Kazuo; Yasui, Nobuyuki

    1991-01-01

    Magnetic resonance imaging of subarachnoid hemorrhage (SAH) due to aneurysm rupture was evaluated in relation to CT findings in nine patients. Six patients were studied within 3 days and the other three patients were studied 4 to 6 days from the ictus of SAH using a 0.5 Tesla superconducting unit. In all of the patients, hematoma in the subarachnoid space and ventricles was demonstrated by the proton density-weighted spin echo sequence, which showed that bloody cerebrospinal fluid (CSF) had a higher signal intensity than brain tissue or normal CSF. Magnetic resonance imaging was more sensitive in detecting SAH and more informative as to the site of the ruptured aneurysm than CT. Despite some limitations in applying it to patients with acute SAH, magnetic resonace imaging has clear advantages in the diagnosis of SAH. (author)

  15. The market for magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Carlson, L.

    1990-01-01

    The medical market is, at present, the most dominant market for low T c superconductors. Indeed, without magnetic resonance imaging (MRI), there would hardly be a low T c superconductor market at all. According to the author, any development that can expand the medical market for MRI machines would be a welcome one. This paper reports how the recent advances in magnetic resonance spectroscopy (MRS) are such a development. While the principle of MRS has bee around as long as MRI, only recently have advances in technique, computer programming and magnet technology allowed MRS to advance to a point where it may become an important technology-one that could increase the medical market for superconductors. The author discussed how MRS can be used to analyze oil core samples for their oil content, oil/water ratios, how the oil is bound and how to extract it

  16. Magnetic resonance imaging of aneurysmal subarachnoid hemorrhage

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Toshihide; Shimosegawa, Eku; Inugami, Atsushi; Shishido, Fumio; Fujita, Hideaki; Ito, Hiroshi; Uemura, Kazuo; Yasui, Nobuyuki (Research Inst. of Brain and Blood Vessels, Akita (Japan))

    1991-11-01

    Magnetic resonance imaging of subarachnoid hemorrhage (SAH) due to aneurysm rupture was evaluated in relation to CT findings in nine patients. Six patients were studied within 3 days and the other three patients were studied 4 to 6 days from the ictus of SAH using a 0.5 Tesla superconducting unit. In all of the patients, hematoma in the subarachnoid space and ventricles was demonstrated by the proton density-weighted spin echo sequence, which showed that bloody cerebrospinal fluid (CSF) had a higher signal intensity than brain tissue or normal CSF. Magnetic resonance imaging was more sensitive in detecting SAH and more informative as to the site of the ruptured aneurysm than CT. Despite some limitations in applying it to patients with acute SAH, magnetic resonace imaging has clear advantages in the diagnosis of SAH. (author).

  17. Clinical application of functional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Alwatban, Adnan Z.W.

    2002-01-01

    The work described in this thesis was carried out at the Magnetic Resonance Centre of the University of Nottingham during the time from May 1998 to April 2001, and is the work of the author except where indicated by reference. The main source of signal changes in functional magnetic resonance imaging (fMRJ) is the fluctuation of paramagnetic deoxyhaemoglobin in the venous blood during different states of functional performance. For the work of this thesis, fMRI studies were carried out using a 3 T MR system with an echo planar imaging (EPI) pulse sequence. Hearing research utilising fMRI has been previously reported in normal subjects. Hearing fMRI is normally performed by stimulating the auditory cortex via an acoustic task presentation such as music, tone, etc. However, performing the same research on deaf subjects requires special equipment to be designed to allow direct stimulation of the auditory nerve. In this thesis, a new method of direct electrical stimulation of the auditory nerve is described that uses a transtympanic electrode implanted onto the surface of the cochlea. This approach would however, result in electromotive forces (EMFs) being induced by the time varying magnetic field, which would lead to current flow and heating, as well as deflection of the metallic electrode within the static magnetic field, and image distortion due to the magnetic susceptibility difference. A gold-plated tungsten electrode with a zero magnetic susceptibility was developed to avoid image distortion. Used with carbon leads and a carbon reference pad, it enabled safe, distortion-free fMRI studies of deaf subjects. The study revealed activation of the primary auditory cortex. This fMRI procedure can be used to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for pre-operative assessment of candidates for cochlear implantation. Glucose is the energy source on which the function of the human brain is entirely dependent. Failure to

  18. Clinical application of functional magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Alwatban, Adnan Z W

    2002-07-01

    The work described in this thesis was carried out at the Magnetic Resonance Centre of the University of Nottingham during the time from May 1998 to April 2001, and is the work of the author except where indicated by reference. The main source of signal changes in functional magnetic resonance imaging (fMRJ) is the fluctuation of paramagnetic deoxyhaemoglobin in the venous blood during different states of functional performance. For the work of this thesis, fMRI studies were carried out using a 3 T MR system with an echo planar imaging (EPI) pulse sequence. Hearing research utilising fMRI has been previously reported in normal subjects. Hearing fMRI is normally performed by stimulating the auditory cortex via an acoustic task presentation such as music, tone, etc. However, performing the same research on deaf subjects requires special equipment to be designed to allow direct stimulation of the auditory nerve. In this thesis, a new method of direct electrical stimulation of the auditory nerve is described that uses a transtympanic electrode implanted onto the surface of the cochlea. This approach would however, result in electromotive forces (EMFs) being induced by the time varying magnetic field, which would lead to current flow and heating, as well as deflection of the metallic electrode within the static magnetic field, and image distortion due to the magnetic susceptibility difference. A gold-plated tungsten electrode with a zero magnetic susceptibility was developed to avoid image distortion. Used with carbon leads and a carbon reference pad, it enabled safe, distortion-free fMRI studies of deaf subjects. The study revealed activation of the primary auditory cortex. This fMRI procedure can be used to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for pre-operative assessment of candidates for cochlear implantation. Glucose is the energy source on which the function of the human brain is entirely dependent. Failure to

  19. Transcranial magnetic stimulation assisted by neuronavigation of magnetic resonance images

    Science.gov (United States)

    Viesca, N. Angeline; Alcauter, S. Sarael; Barrios, A. Fernando; González, O. Jorge J.; Márquez, F. Jorge A.

    2012-10-01

    Technological advance has improved the way scientists and doctors can learn about the brain and treat different disorders. A non-invasive method used for this is Transcranial Magnetic Stimulation (TMS) based on neuron excitation by electromagnetic induction. Combining this method with functional Magnetic Resonance Images (fMRI), it is intended to improve the localization technique of cortical brain structures by designing an extracranial localization system, based on Alcauter et al. work.

  20. Magnetic resonance imaging in otolaryngology

    International Nuclear Information System (INIS)

    Gradzki, J.; Paprzycki, W.

    1993-01-01

    In the paper authors describe fundamental physical properties of a phenomenon of the radio-frequency excitation and relaxation of nuclei ordered in a strong magnetic field and the usefulness of MRI in medical diagnostic procedures. Basic interpretations principles of MR imaging due to signal intensity differences between organs and tissues in T 1 - and T 2 - weighted sequences and proton density are presented. Both, literature review and experience of authors suggest application of MRI in otolaryngology, it is illustrated by a lot of examples. The MR imaging studies were compared with results obtained from CT in otolaryngology field. (author)

  1. Magnetic Resonance Imaging (MRI): Lumbar Spine (For Parents)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Magnetic Resonance Imaging (MRI): Lumbar Spine KidsHealth / For Parents / Magnetic Resonance Imaging (MRI): Lumbar Spine What's in this article? ...

  2. Magnetic resonance imaging by using nano-magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Khorramdin, A. [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Isapour, Gh. [Department of Materials and Engineering, Hakim Sabzevari University (Iran, Islamic Republic of)

    2014-11-15

    Magnetism and magnetic materials play a major role in various biological applications, such as magnetic bioseparation, magnetic resonance imaging (MRI), hyperthermia treatment of cancer and drug delivery. Among these techniques, MRI is a powerful method not only for diagnostic radiology but also for therapeutic medicine that utilizes a magnetic field and radio waves. Recently, this technique has contributed greatly to the promotion of the human quality life. Thus, this paper presents a short review of the physical principles and recent advances of MRI, as well as providing a summary of the synthesis methods and properties of contrast agents, like different core materials and surfactants. - Highlights: • This paper studies the physics of MRI as a powerful diagnostic technique. • MRI uses the differentiation between healthy and pathological tissues. • The relaxation times can be shortened by the use of a magnetic contrast agent. • The magnetic nanoparticles act as contrast agents, helping to increase the resolution. • Different synthesis methods can influence the magnetic resonance behavior.

  3. BOLD magnetic resonance imaging in nephrology

    Science.gov (United States)

    Hall, Michael E; Jordan, Jennifer H; Juncos, Luis A; Hundley, W Gregory; Hall, John E

    2018-01-01

    Magnetic resonance (MR) imaging, a non-invasive modality that provides anatomic and physiologic information, is increasingly used for diagnosis of pathophysiologic conditions and for understanding renal physiology in humans. Although functional MR imaging methods were pioneered to investigate the brain, they also offer powerful techniques for investigation of other organ systems such as the kidneys. However, imaging the kidneys provides unique challenges due to potential complications from contrast agents. Therefore, development of non-contrast techniques to study kidney anatomy and physiology is important. Blood oxygen level-dependent (BOLD) MR is a non-contrast imaging technique that provides functional information related to renal tissue oxygenation in various pathophysiologic conditions. Here we discuss technical considerations, clinical uses and future directions for use of BOLD MR as well as complementary MR techniques to better understand renal pathophysiology. Our intent is to summarize kidney BOLD MR applications for the clinician rather than focusing on the complex physical challenges that functional MR imaging encompasses; however, we briefly discuss some of those issues. PMID:29559807

  4. Magnetic resonance imaging of the normal placenta

    International Nuclear Information System (INIS)

    Blaicher, Wibke; Brugger, Peter C.; Mittermayer, Christoph; Schwindt, Jens; Deutinger, Josef; Bernaschek, Gerhard; Prayer, Daniela

    2006-01-01

    The goal of this study was to provide a representative description of the normal placenta with contrast medium-free magnetic resonance imaging (MRI) in order to determine a standard of reference. One hundred consecutive singleton pregnancies were investigated by MRI without application of a contrast medium. The mean gestational age (GA) at the time of investigation was 29.5 weeks (range 19-40). Patients with suspected utero-placental insufficiency (UPI) or placental anomalies were excluded. Signal intensities were assessed and correlated with the respective GA. Antenatal MRI without contrast medium was able to depict placental status and morphological changes during gestation. A regular homogeneous structure was found in weeks 19-23. Subsequently, sporadic, slightly marked lobules appeared, which increased in number and markedness with ongoing gestation. Stratification of the lobules was observed after 36 weeks. The ratio of placental and amniotic fluid signal intensities decreased significantly with higher GA and with placental grading. MRI is well suited as an imaging method for the placenta. Our data may be used as a reference in the assessment of the placenta on MRI, and may have further clinical impact with respect to the determination of UPI

  5. BOLD magnetic resonance imaging in nephrology

    Directory of Open Access Journals (Sweden)

    Hall ME

    2018-03-01

    Full Text Available Michael E Hall,1,2 Jennifer H Jordan,3 Luis A Juncos,1,2 W Gregory Hundley,3 John E Hall2 1Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA; 2Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA; 3Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA Abstract: Magnetic resonance (MR imaging, a non-invasive modality that provides anatomic and physiologic information, is increasingly used for diagnosis of pathophysiologic conditions and for understanding renal physiology in humans. Although functional MR imaging methods were pioneered to investigate the brain, they also offer powerful techniques for investigation of other organ systems such as the kidneys. However, imaging the kidneys provides unique challenges due to potential complications from contrast agents. Therefore, development of non-contrast techniques to study kidney anatomy and physiology is important. Blood oxygen level-dependent (BOLD MR is a non-contrast imaging technique that provides functional information related to renal tissue oxygenation in various pathophysiologic conditions. Here we discuss technical considerations, clinical uses and future directions for use of BOLD MR as well as complementary MR techniques to better understand renal pathophysiology. Our intent is to summarize kidney BOLD MR applications for the clinician rather than focusing on the complex physical challenges that functional MR imaging encompasses; however, we briefly discuss some of those issues. Keywords: functional MRI, kidney, oxygenation, chronic kidney disease 

  6. Magnetic resonance imaging of the normal placenta

    Energy Technology Data Exchange (ETDEWEB)

    Blaicher, Wibke [Department of Gynecology and Obstetrics, University Hospital Vienna (Austria)]. E-mail: wibke.blaicher@meduniwien.ac.at; Brugger, Peter C. [Center of Anatomy and Cell Biology, University Hospital of Vienna (Austria); Mittermayer, Christoph [Department of Pediatrics, Division of Neonatology and Intensive Care, University Hospital of Vienna (Austria); Schwindt, Jens [Department of Pediatrics, Division of Neonatology and Intensive Care, University Hospital of Vienna (Austria); Deutinger, Josef [Department of Gynecology and Obstetrics, University Hospital Vienna (Austria); Bernaschek, Gerhard [Department of Gynecology and Obstetrics, University Hospital Vienna (Austria); Prayer, Daniela [Department of Radiology, Division of Neuroradiology, University Hospital of Vienna (Austria)

    2006-02-15

    The goal of this study was to provide a representative description of the normal placenta with contrast medium-free magnetic resonance imaging (MRI) in order to determine a standard of reference. One hundred consecutive singleton pregnancies were investigated by MRI without application of a contrast medium. The mean gestational age (GA) at the time of investigation was 29.5 weeks (range 19-40). Patients with suspected utero-placental insufficiency (UPI) or placental anomalies were excluded. Signal intensities were assessed and correlated with the respective GA. Antenatal MRI without contrast medium was able to depict placental status and morphological changes during gestation. A regular homogeneous structure was found in weeks 19-23. Subsequently, sporadic, slightly marked lobules appeared, which increased in number and markedness with ongoing gestation. Stratification of the lobules was observed after 36 weeks. The ratio of placental and amniotic fluid signal intensities decreased significantly with higher GA and with placental grading. MRI is well suited as an imaging method for the placenta. Our data may be used as a reference in the assessment of the placenta on MRI, and may have further clinical impact with respect to the determination of UPI.

  7. Musculoskeletal applications of magnetic resonance imaging: Council on Scientific Affairs

    International Nuclear Information System (INIS)

    Harms, S.E.; Fisher, C.F.; Fulmer, J.M.

    1989-01-01

    Magnetic resonance imaging provides superior contrast, resolution, and multiplanar imaging capability, allowing excellent definition of soft-tissue and bone marrow abnormalities. For these reasons, magnetic resonance imaging has become a major diagnostic imaging method for the evaluation of many musculoskeletal disorders. The applications of magnetic resonance imaging for musculoskeletal diagnosis are summarized and examples of common clinical situations are given. General guidelines are suggested for the musculoskeletal applications of magnetic resonance imaging

  8. Magnetic structure and resonance properties of hexagonal antidot lattice

    International Nuclear Information System (INIS)

    Marchenko, A.I.; Krivoruchko, V.N.

    2012-01-01

    Static and resonance properties of ferromagnetic films with an antidot lattice (pores in the film) are studied. The description of the system is based on micromagnetic modeling and analytical solution of the Landau-Lifshitz equation. The dependences of ferromagnetic resonance spectra on the in-plane direction of applied magnetic field and on the lattice parameters are investigated. The dependences of a dynamic system response on frequency at fixed magnetic field and on field at fixed frequency, when the field changes cause the static magnetic order to change are explored. It is found that the specific peculiarities of the system dynamics leave unchange for both of these experimental conditions. Namely, for low damping the resonance spectra contain three quasi-homogeneous modes which are due to the resonance of different regions (domains) of the antidot lattice cell. It is shown the angular field dependences of each mode are characterized by a twofold symmetry and the related easy axes are mutually rotated by 60 degrees. As the result, a hexagonal symmetry of the system static and dynamic magnetic characteristics is realized. The existence in the resonance spectrum of several quasi-homogeneous modes related to different regions of the unit cell could be fundamental for working elements of magnonic devices.

  9. Physics of Magnetic Resonance. Chapter 14

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hee Kwon [Hospital of the University of Pennsylvania, Philadelphia (United States)

    2014-09-15

    The discovery of nuclear magnetic resonance (NMR), a property of nuclei in a magnetic field where they are able to absorb applied radiofrequency (RF) energy and subsequently release it at a specific frequency, goes back many decades to the early 1900s. Physicist Isidor I. Rabi, fascinated by the work of Otto Stern and Walther Gerlach which demonstrated that particles have intrinsic quantum properties, delved into the magnetic properties of nuclei, and in 1938 Rabi discovered the phenomenon of NMR. Several years later, in 1946, Felix Bloch and Edward Purcell refined the methods and successfully measured the NMR signal from liquids and solids. For their discoveries, Rabi received the Nobel Prize for physics in 1944 and Bloch and Purcell in 1952. While Rabi, Bloch, Purcell and other physicists working in this field had laid the foundations, a major discovery that transformed the NMR phenomenon for imaging was not made until 1973, when Paul Lauterbur developed a method for spatially encoding the NMR signal by utilizing linear magnetic field gradients. About the same time, Peter Mansfield had also discovered a means of determining the spatial structure of solids by introducing a linear gradient across the object. The idea of applying magnetic field gradients to induce spatially varying resonance frequencies to resolve the spatial distribution of magnetization was a major milestone and the beginning of magnetic resonance imaging (MRI). For their work, Lauterbur and Mansfield were awarded the Nobel Prize for medicine in 2003. Since its discovery, MRI has quickly become one of the most important medical imaging devices available to physicians today. Unlike other imaging modalities, such as X ray and computed tomography, MRI does not involve ionizing radiation. MRI also offers superior soft tissue contrast that is not possible with other imaging modalities. Furthermore, in MRI, the desired level of image contrast among different tissues can often be precisely controlled

  10. 76 FR 58281 - Magnetic Resonance Imaging Safety; Public Workshop

    Science.gov (United States)

    2011-09-20

    ...] Magnetic Resonance Imaging Safety; Public Workshop AGENCY: Food and Drug Administration, HHS. ACTION... announcing a public workshop entitled: ``Magnetic Resonance Imaging (MRI) Safety Public Workshop.'' The purpose of the public workshop is to discuss factors affecting the safe use of magnetic resonance imaging...

  11. Functional magnetic resonance imaging of the primary motor cortex ...

    Indian Academy of Sciences (India)

    Unknown

    Abbreviations used: BOLD, Blood oxygenation level dependent; CBF, cerebral blood flow; fMRI, functional magnetic resonance imaging; EPI, eco-planar imaging; FOV, field of view; MRI, Magnetic resonance imaging; MRS, magnetic resonance spectroscopy;. PET, position emission tomography; rCBF, regional cerebral ...

  12. Nuclear magnetic resonance in ferromagnetic terbium metal

    International Nuclear Information System (INIS)

    Cha, C.L.T.

    1974-01-01

    The magnetic properties of terbium were studied by the method of zero field nuclear magnetic resonance at 1.5 to 4 and 85 to 160 0 K. Two unconventional experimental techniques have been employed: the swept frequency and the swept temperature technique. Near 4 0 K, triplet resonance line structures were found and interpreted in terms of the magnetic domain and wall structures of ferromagnetic terbium. In the higher temperature range, temperature dependence of the resonance frequency and the quadrupole splitting were measured. The former provides a measurement of the temperature dependence of the magnetization M, and it agrees with bulk M measurements as well as the latest spin wave theory of M(T) (Brooks 1968). The latter agrees well with a calculation using a very general single ion density matrix for collective excitations (Callen and Shtrikman 1965). In addition, the small temperature-independent contribution to the electric field gradient at the nucleus due to the lattice and conduction electrons was untangled from the P(T) data. Also an anomalous and unexplained relaxation phenomenon was also observed

  13. [Magnetic resonance compatibility research for coronary mental stents].

    Science.gov (United States)

    Wang, Ying; Liu, Li; Wang, Shuo; Shang, Ruyao; Wang, Chunren

    2015-01-01

    The objective of this article is to research magnetic resonance compatibility for coronary mental stents, and to evaluate the magnetic resonance compatibility based on laboratory testing results. Coronary stents magnetic resonance compatibility test includes magnetically induced displacement force test, magnetically induced torque test, radio frequency induced heating and evaluation of MR image. By magnetic displacement force and torque values, temperature, and image distortion values to determine metal coronary stent demagnetization effect. The methods can be applied to test magnetic resonance compatibility for coronary mental stents and evaluate its demagnetization effect.

  14. A hyperpolarized equilibrium for magnetic resonance.

    Science.gov (United States)

    Hövener, Jan-Bernd; Schwaderlapp, Niels; Lickert, Thomas; Duckett, Simon B; Mewis, Ryan E; Highton, Louise A R; Kenny, Stephen M; Green, Gary G R; Leibfritz, Dieter; Korvink, Jan G; Hennig, Jürgen; von Elverfeldt, Dominik

    2013-01-01

    Nuclear magnetic resonance spectroscopy and imaging (MRI) play an indispensable role in science and healthcare but use only a tiny fraction of their potential. No more than ≈10 p.p.m. of all ¹H nuclei are effectively detected in a 3-Tesla clinical MRI system. Thus, a vast array of new applications lays dormant, awaiting improved sensitivity. Here we demonstrate the continuous polarization of small molecules in solution to a level that cannot be achieved in a viable magnet. The magnetization does not decay and is effectively reinitialized within seconds after being measured. This effect depends on the long-lived, entangled spin-order of parahydrogen and an exchange reaction in a low magnetic field of 10⁻³ Tesla. We demonstrate the potential of this method by fast MRI and envision the catalysis of new applications such as cancer screening or indeed low-field MRI for routine use and remote application.

  15. Vision research with functional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Nakadomari, Satoshi

    1999-01-01

    Present state of functional magnetic resonance imaging (fMRI), which is based on changes of MR signals produced by blood circulation changes due to the nerve activity, in vision research was reviewed. In this field, there are international associations of Human Brain Mapping and for Research in Vision and Ophthalmology (ARVO) and reports presented in ARVO in 1998 and 1999 were firstly described. Next, the comparison between two conditions was defined as the experimental paradigm of fMRI and analyses with the event related fMRI and with classification into visual central regions were explained. Major findings obtained by stimulation of visual central regions were discussed on the lateral corpus geniculatum, areas of V1, V2, V3 (VP), V3A, V4A (V8), V5 and LO (lateral occipital complex), and others. In practice of actual fMRI, the noise is often attributable to the examinee factor and notification for speculating the result is important. The value of fMRI in the clinical ophthalmological diagnosis was discussed and thought to be further investigated. (K.H.)

  16. Magnetic resonance imaging of splenic iron overload

    International Nuclear Information System (INIS)

    Arrive, L.; Thurnher, S.; Hricak, H.; Price, D.C.

    1990-01-01

    The value of magnetic resonance (MR) imaging in assessing iron overload in the spleen was retrospectively investigated in 40 consecutive patients. MR appearance, mesaure of signal intensity and T1-and T2-relaxation times were correlated with the histologically determined level of iron in the spleen in each patient. Histologic examination revealed no iron overload in 19 patients, mild iron overload in seven, moderate iron overload in six, and severe iron overload in eight. All 19 patients with no splenic iron overload and 11 of the other 21 patients with splenic iron overload were correctly identified by MR imaging (sensitivity 52%, specificity 100%, accuracy 75%). Splenic iron overload was diagnosed when a decrease of signal intensity of the spleen compared with those of adipose tissue and renal cortex was demonstrated. MR images demonstrated all eight cases of severe, three of the six cases of moderate, and none of the seven cases of mild iron overload. Only spleens with severe iron overload had a significant mean decrease in signal intensity and T1- and T2-relaxation times. Although specific, MR imaging is poorly sensitive to splenic iron overload. (author). 15 refs.; 5 figs.; 3 tabs

  17. Nuclear magnetic resonance imaging in pharmaceutical research

    International Nuclear Information System (INIS)

    Sarkar, S.K.

    1991-01-01

    Nuclear magnetic resonance imaging has important applications in pharmaceutical research since it allows specific tissue and disease characterization in animal models noninvasively with excellent anatomical resolution and therefore provides improved ability to monitor the efficacy of novel drugs. The utility of NMR imaging in renal studies to monitor the mechanism of drug action and renal function in rats is described. The extension of the resolution of an NMR image to microscopic domain at higher magnetic field strengths and the utility of NMR microimaging in cerebrovascular and tumour metastasis studies in mice are discussed. (author). 40 refs., 14 figs

  18. Proton magnetic resonance spectroscopy in the fetus.

    Science.gov (United States)

    Story, Lisa; Damodaram, Mellisa S; Allsop, Joanna M; McGuinness, Amy; Wylezinska, Marzena; Kumar, Sailesh; Rutherford, Mary A

    2011-09-01

    Magnetic Resonance Imaging (MRI) has become an established technique in fetal medicine, providing complementary information to ultrasound in studies of the brain. MRI can provide detailed structural information irrespective of the position of the fetal head or maternal habitus. Proton Magnetic Resonance Spectroscopy ((1)HMRS) is based on the same physical principles as MRI but data are collected as a spectrum, allowing the biochemical and metabolic status of in vivo tissue to be studied in a non-invasive manner. (1)HMRS has been used to assess metabolic function in the neonatal brain but fetal studies have been limited, primarily due to fetal motion. This review will assess the technique and findings from fetal studies to date. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  19. Magnetic resonance studies of intercalation compounds

    International Nuclear Information System (INIS)

    Miller, G.R.

    1990-01-01

    During the last three or four years, nearly tow hundred papers have been published that used NMR or ESR spectroscopy to study compounds formed by the intercalation of molecules or ions into the van der Waals gap of a layered hast compound. The host lattices have ranged from the simple, such as graphite, to the complex, such as clay. In many cases, magnetic resonance techniques now enable one to obtain quite detailed information on even fairly complex intercalated species, on the nature of the changes in the host lattice accompanying intercalation, and on the nature of the interactions between the intercalant species and the host lattice. Magnetic resonance is used in conunction with many other techniques to obtain a fuller picture of these interesting systems, but this review will limit its focus to the use of NMR and ESR techniques. (author). 51 refs

  20. Sensorineural hearing loss after magnetic resonance imaging

    DEFF Research Database (Denmark)

    Mollasadeghi, Abolfazl; Mehrparvar, Amir Houshang; Atighechi, Saeid

    2013-01-01

    Magnetic resonance imaging (MRI) devices produce noise, which may affect patient's or operators' hearing. Some cases of hearing impairment after MRI procedure have been reported with different patterns (temporary or permanent, unilateral or bilateral, with or without other symptoms like tinnitus)......). In this report, a case of bilateral sensorineural hearing loss in an otherwise healthy patient underwent brain MRI was described. The patient's hearing loss was accompanied with tinnitus and was not improved after 3 months of followup.......Magnetic resonance imaging (MRI) devices produce noise, which may affect patient's or operators' hearing. Some cases of hearing impairment after MRI procedure have been reported with different patterns (temporary or permanent, unilateral or bilateral, with or without other symptoms like tinnitus...

  1. Magnetic resonance imaging findings in tuberculous meningoencephalitis

    Energy Technology Data Exchange (ETDEWEB)

    Pui, M.H.; Memon, W.A. [Aga Khan Univ. Hospital, Dept. of Radiology, Karachi (Pakistan)

    2001-02-01

    To evaluate the efficacy of magnetic resonance imaging (MRI) for distinguishing tuberculosis from other types of meningoencephalitis. MRIs of 100 patients with tuberculous (50), pyogenic (33), viral (14), or fungal (3) meningoencephalitis were analyzed independently by 2 radiologists. Number, size, location, signal characteristics, surrounding edema, and contrast enhancement pattern of nodular lesions; location and pattern of meningeal enhancement; extent of infarct or encephalitis and hydrocephalus were evaluated. Contrast-enhancing nodular lesions were detected in patients with tuberculous (43 of 50 patients), pyogenic (9 of 33), and fungal (3 of 3) infections. No nodules were detected in patients with viral meningoencephalitis. Using the criteria of 1 or more solid rim or homogeneously enhancing nodules smaller than 2 cm, the sensitivity, specificity and accuracy for diagnosing tuberculous meningitis were 86.0%, 90.0% and 88.0%, respectively. Magnetic resonance imaging is useful in distinguishing tuberculous from pyogenic, viral and fungal meningoencephalitis. (author)

  2. Investigation of the metabolic changes in visual cortex due to visual stimulation using high field magnetic resonance spectroscopy at 7.0 T

    International Nuclear Information System (INIS)

    Lin Yan; Peter, M.; Wu Renhua

    2012-01-01

    Objective: To investigate the metabolic changes in the visual cortex due to visual stimulation using high field functional proton magnetic resonance spectroscopy at 7.0 T. A clear picture of brain metabolism and neurotransmitter activity during activation was expected to be established. Methods: Nine healthy subjects participated in this study. All MR measurements were acquired using a 7.0 T MR system and a 16-channel SENSE head coil. An initial fMRI scan was performed prior to spectroscopic acquisition in order to determine the activated region in the visual cortex. A cubic ROI of 2 cm× 2 cm × 2 cm was positioned inside the activated region for functional MRS acquisition. A short TE STEAM sequence was used for acquiring the MRS data. The functional paradigm comprised 6.6 min baseline followed by 13.2 min of visual stimulation and 19.8 min recovery. Summed averaged spectra for visual stimulus off and visual stimulus on were analyzed separately using LC Model and internal reference of water. A Wilcoxon signed rank test was conducted to compare the metabolite changes. Results During stimulation, concentration in Asp [(3.20 ± 0.28) μmol/g], Gln [(2.07 ± 0.10) μmol/g] and Gly [(1.65 ± 0.11)μmol/g] was found to be significantly decreased,compared with that of (3.52 ± 0.28), (2.25 ± 0.10) and (1.85 ± 0.11) μmol/g in rest (Z=-2.073, -2.073 and -2.429, respectively, P<0.05). The level in Glu [(11.50 ± 0.11) μmol/g], GSH [(2.45 ± 0.10) μmol/g] and Lac [(0.89 ± 0.05) μmol/g] due to neuronal activation was found to be significantly increased,versus resting concentration of (11.28 ± 0.11), (2.28 ± 0.10) and (0.79 ± 0.05) μmol/g,respectively (Z=2.521, 2.310, 2.016, respectively, P<0.05). Glc level [(1.54 ± 0.23)μmol/g] exhibited a tendency to decrease throughout the period of stimulation, compared with that of [(1.78 ± 0.28) μmol/g] in rest,but the decrease did not reach statistical significance (Z=-1.897, P>0.05). Conclusions: Using a novel visual

  3. Two-dimensional nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Bax, A.; Lerner, L.

    1986-01-01

    Great spectral simplification can be obtained by spreading the conventional one-dimensional nuclear magnetic resonance (NMR) spectrum in two independent frequency dimensions. This so-called two-dimensional NMR spectroscopy removes spectral overlap, facilitates spectral assignment, and provides a wealth of additional information. For example, conformational information related to interproton distances is available from resonance intensities in certain types of two-dimensional experiments. Another method generates 1 H NMR spectra of a preselected fragment of the molecule, suppressing resonances from other regions and greatly simplifying spectral appearance. Two-dimensional NMR spectroscopy can also be applied to the study of 13 C and 15 N, not only providing valuable connectivity information but also improving sensitivity of 13 C and 15 N detection by up to two orders of magnitude. 45 references, 10 figures

  4. OPTIMAL EXPERIMENT DESIGN FOR MAGNETIC RESONANCE FINGERPRINTING

    OpenAIRE

    Zhao, Bo; Haldar, Justin P.; Setsompop, Kawin; Wald, Lawrence L.

    2016-01-01

    Magnetic resonance (MR) fingerprinting is an emerging quantitative MR imaging technique that simultaneously acquires multiple tissue parameters in an efficient experiment. In this work, we present an estimation-theoretic framework to evaluate and design MR fingerprinting experiments. More specifically, we derive the Cram��r-Rao bound (CRB), a lower bound on the covariance of any unbiased estimator, to characterize parameter estimation for MR fingerprinting. We then formulate an optimal experi...

  5. Magnetic resonance in multiple sclerose twins

    International Nuclear Information System (INIS)

    Polman, C.H.; UitdeHaag, B.M.J.; Koetsier, C.J.; Valk, J.; Lucas, C.J.

    1989-01-01

    Magnetic resonance imaging (MR) examinations were performed in a series of 7 twin sets (4 monozygotic and 3 dizygotic) and one triplet set who were clinically discordant for multiple sclerosis (MS). MRI abnormalities were detected in a number of the unaffected members of the nonzygotic twin pairs. The authors discuss the possible implications of their findings for the present view on the aetiology of MS. (author). 3 refs.; 1 fig.; 1 tab

  6. Basic principles of nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Valk, J.; MacLean, C.; Algra, P.R.

    1985-01-01

    The intent of this book is to help clinicians understand the basic physical principles of magnetic resonance (MR) imaging. The book consists of the following: a discussion of elementary considerations; pulse sequencing; localization of MR signals in space; MR equipment; MR contrast agents; clinical applications; MR spectroscopy; and biological effects of MR imaging; a set of appendixes; and a bibliography. Illustrations and images are included

  7. BOLD magnetic resonance imaging in nephrology

    OpenAIRE

    Hall ME; Jordan JH; Juncos LA; Hundley WG; Hall JE

    2018-01-01

    Michael E Hall,1,2 Jennifer H Jordan,3 Luis A Juncos,1,2 W Gregory Hundley,3 John E Hall2 1Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA; 2Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA; 3Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA Abstract: Magnetic resonance (MR) imaging, a non-invasive modality that provides ana...

  8. Measurement of myocardial perfusion using magnetic resonance

    DEFF Research Database (Denmark)

    Fritz-Hansen, T.; Jensen, L.T.; Larsson, H.B.

    2008-01-01

    Cardiac magnetic resonance imaging (MRI) has evolved rapidly. Recent developments have made non-invasive quantitative myocardial perfusion measurements possible. MRI is particularly attractive due to its high spatial resolution and because it does not involve ionising radiation. This paper reviews...... myocardial perfusion imaging with MR contrast agents: methods, validation and experiences from clinical studies. Unresolved issues still restrict the use of these techniques to research although clinical applications are within reach Udgivelsesdato: 2008/12/8...

  9. Sensorineural hearing loss after magnetic resonance imaging

    DEFF Research Database (Denmark)

    Mollasadeghi, Abolfazl; Mehrparvar, Amir Houshang; Atighechi, Saeid

    2013-01-01

    Magnetic resonance imaging (MRI) devices produce noise, which may affect patient's or operators' hearing. Some cases of hearing impairment after MRI procedure have been reported with different patterns (temporary or permanent, unilateral or bilateral, with or without other symptoms like tinnitus......). In this report, a case of bilateral sensorineural hearing loss in an otherwise healthy patient underwent brain MRI was described. The patient's hearing loss was accompanied with tinnitus and was not improved after 3 months of followup....

  10. Magnetic resonance imaging in MELAS syndrome

    International Nuclear Information System (INIS)

    Rosen, L.; Phillips, S.; Enzmann, D.

    1990-01-01

    MELAS syndrome is a distinct clinical entity belonging to a group of mitochondrial encephalomyopathies characterized by the tetrad of myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. Computed tomography (CT) and magnetic resonance (MR) findings are reviewed in a patient with MELAS. Serial CT studies demonstrated multiple 'migrating' infarcts in various stages of evolution involving primarily the posterior temporal and occipital regions. MR was more sensitive than CT in demonstrating the number and extent of cortical lesions in this disease entity. (orig.)

  11. Magnetic Resonance Fingerprinting with short relaxation intervals.

    Science.gov (United States)

    Amthor, Thomas; Doneva, Mariya; Koken, Peter; Sommer, Karsten; Meineke, Jakob; Börnert, Peter

    2017-09-01

    The aim of this study was to investigate a technique for improving the performance of Magnetic Resonance Fingerprinting (MRF) in repetitive sampling schemes, in particular for 3D MRF acquisition, by shortening relaxation intervals between MRF pulse train repetitions. A calculation method for MRF dictionaries adapted to short relaxation intervals and non-relaxed initial spin states is presented, based on the concept of stationary fingerprints. The method is applicable to many different k-space sampling schemes in 2D and 3D. For accuracy analysis, T 1 and T 2 values of a phantom are determined by single-slice Cartesian MRF for different relaxation intervals and are compared with quantitative reference measurements. The relevance of slice profile effects is also investigated in this case. To further illustrate the capabilities of the method, an application to in-vivo spiral 3D MRF measurements is demonstrated. The proposed computation method enables accurate parameter estimation even for the shortest relaxation intervals, as investigated for different sampling patterns in 2D and 3D. In 2D Cartesian measurements, we achieved a scan acceleration of more than a factor of two, while maintaining acceptable accuracy: The largest T 1 values of a sample set deviated from their reference values by 0.3% (longest relaxation interval) and 2.4% (shortest relaxation interval). The largest T 2 values showed systematic deviations of up to 10% for all relaxation intervals, which is discussed. The influence of slice profile effects for multislice acquisition is shown to become increasingly relevant for short relaxation intervals. In 3D spiral measurements, a scan time reduction of 36% was achieved, maintaining the quality of in-vivo T1 and T2 maps. Reducing the relaxation interval between MRF sequence repetitions using stationary fingerprint dictionaries is a feasible method to improve the scan efficiency of MRF sequences. The method enables fast implementations of 3D spatially

  12. Parameter dependence of resonant spin torque magnetization reversal

    International Nuclear Information System (INIS)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H.W.

    2012-01-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  13. Parameter dependence of resonant spin torque magnetization reversal

    Science.gov (United States)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H. W.

    2012-04-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  14. Nuclear Magnetic Resonance, a Powerful Tool in Cultural Heritage

    OpenAIRE

    Noemi Proietti; Donatella Capitani; Valeria Di Tullio

    2018-01-01

    In this paper five case studies illustrating applications of NMR (Nuclear Magnetic Resonance) in the field of cultural heritage, are reported. Different issues were afforded, namely the investigation of advanced cleaning systems, the quantitative mapping of moisture in historic walls, the investigation and evaluation of restoration treatments on porous stones, the stratigraphy of wall paintings, and the detection of CO2 in lapis lazuli. Four of these case studies deal with the use of portable...

  15. Thermal and particle size distribution effects on the ferromagnetic resonance in magnetic fluids

    International Nuclear Information System (INIS)

    Marin, C.N.

    2006-01-01

    Thermal and particle size distribution effects on the ferromagnetic resonance of magnetic fluids were theoretically investigated, assuming negligible interparticle interactions and neglecting the viscosity of the carrier liquid. The model is based on the usual approach for the ferromagnetic resonance description of single-domain magnetic particle systems, which was amended in order to take into account the finite particle size effect, the particle size distribution and the orientation mobility of the particles within the magnetic fluid. Under these circumstances the shape of the resonance line, the resonance field and the line width are found to be strongly affected by the temperature and by the particle size distribution of magnetic fluids

  16. Image production by magnetic resonance: transparency via the atom

    International Nuclear Information System (INIS)

    Kanel, A.

    1984-01-01

    The author gives a general description of the nuclear magnetic resonance technique to study the human body. The use of superconducting magnets to generate the required magnetic field is discussed. (G.T.H.)

  17. Magnetically coupled Fano resonance of dielectric pentamer oligomer

    International Nuclear Information System (INIS)

    Zhang, Fuli; Li, Chang; He, Xuan; Chen, Lei; Fan, Yuancheng; Zhao, Qian; Zhang, Weihong; Zhou, Ji

    2017-01-01

    We present magnetically induced Fano resonance inside a dielectric metamaterial pentamer composed of ceramic bricks. Unlike previous reports where different sizes of dielectric resonators were essential to produce Fano resonance, under external magnetic field excitation, central and outer dielectric bricks with identical sizes exhibit in-phase and out-of-phase magnetic Mie oscillations. An asymmetric line shape of Fano resonance along with enhanced group delay is observed due to the interference between the magnetic resonance of the central brick and the symmetric magnetic resonance of outer bricks. Besides, Fano resonance blueshifts with the increasing resonance of the smaller central brick. The thermal-dependent permittivity of ceramics allows Fano resonance to be reversibly tuned by 300 MHz when temperature varies by 60 °C. (paper)

  18. Investigation of Cortical Glutamate–Glutamine and γ-Aminobutyric Acid in Obsessive–Compulsive Disorder by Proton Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Simpson, Helen B; Shungu, Dikoma C; Bender, James; Mao, Xiangling; Xu, Xiaoyan; Slifstein, Mark; Kegeles, Lawrence S

    2012-01-01

    Glutamatergic abnormalities in corticostriatal brain circuits are thought to underlie obsessive–compulsive disorder (OCD). Whether these abnormalities exist in adults with OCD is not clear. We used proton magnetic resonance spectroscopy (1H MRS) to test our hypothesis that unmedicated adults with OCD have reduced glutamate plus glutamine (Glx) levels in the medial prefrontal cortex (MPFC) compared with healthy controls. Levels of γ-aminobutyric acid (GABA) were also explored. Twenty-four unmedicated adults with OCD and 22 matched healthy control subjects underwent 1H MRS scans at 3.0 T. Resonances of both Glx and GABA were obtained using the standard J-editing technique and assessed as ratios relative to voxel tissue water (W) in the MPFC (the region of interest) and the dorsolateral prefrontal cortex (DLPFC) to explore the regional specificity of any finding. In the MPFC, Glx/W did not differ by diagnostic group (p=0.98) or sex (p=0.57). However, GABA/W was decreased in OCD (2.16±0.46 × 10−3) compared with healthy controls (2.43±0.45 × 10−3, p=0.045); moreover, age of OCD onset was inversely correlated with MPFC GABA/W (r=−0.50, p=0.015). MPFC GABA/W was higher in females than in males. In the DLPFC, there were no main effects of diagnosis or gender on Glx/W or GABA/W. These data indicate that unmedicated adults with OCD do not have Glx abnormalities in a MPFC voxel that includes the pregenual anterior cingulate cortex. However, they may have decreased MPFC GABA levels. How GABA abnormalities might contribute to corticostriatal dysfunction in OCD deserves further study. PMID:22850733

  19. Cortico-Striatal GABAergic and Glutamatergic Dysregulations in Subjects at Ultra-High Risk for Psychosis Investigated with Proton Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Reyes-Madrigal, Francisco; Mao, Xiangling; León-Ortiz, Pablo; Rodríguez-Mayoral, Oscar; Solís-Vivanco, Rodolfo; Favila, Rafael; Graff-Guerrero, Ariel; Shungu, Dikoma C.

    2016-01-01

    Background: Dysregulations of the major inhibitory and excitatory amino neurotransmitter systems of γ-aminobutyric acid and glutamate, respectively, have been described in patients with schizophrenia. However, it is unclear whether these abnormalities are present in subjects at ultra-high risk for psychosis. Methods: Twenty-three antipsychotic naïve subjects at ultra-high risk and 24 healthy control subjects, matched for age, sex, handedness, cigarette smoking, and parental education, underwent proton magnetic resonance spectroscopy scans in the dorsal caudate bilaterally and the medial prefrontal cortex at 3T. Levels of γ-aminobutyric acid and of the combined resonance of glutamate and glutamine (Glx) were obtained using the standard J-editing technique and expressed as peak area ratios relative to the synchronously acquired unsuppressed voxel water signal. Results: Higher levels of γ-aminobutyric acid (P<.001) and Glx (P=.007) were found in the dorsal caudate of the subjects at ultra-high risk than in the healthy controls. In the medial prefrontal cortex, likewise, both γ-aminobutyric acid (P=.03) and Glx (P=.006) levels were higher in the ultra-high risk group than in the healthy controls. No group differences were found for any of the other metabolites (N-acetylaspartate, total choline, or total creatine) in the 2 regions of interest. Conclusions: This study presents the first evidence of abnormal elevations, in subjects at ultra-high risk, of γ-aminobutyric acid and Glx in 2 brain regions that have been implicated in the pathophysiology of psychosis, warranting longitudinal studies to assess whether these neurotransmitter abnormalities can serve as noninvasive biomarkers of conversion risk to psychosis as well as of illness progression and treatment response. PMID:26364273

  20. SQUID-detected magnetic resonance imaging in microtesla magnetic fields

    International Nuclear Information System (INIS)

    McDermott, Robert; Kelso, Nathan; Lee, SeungKyun; Moessle, Michael; Mueck, Michael; Myers, Whittier; Haken, Bernard ten; Seton, H.C.; Trabesinger, Andreas H.; Pines, Alex; Clarke, John

    2003-01-01

    We describe studies of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) of liquid samples at room temperature in microtesla magnetic fields. The nuclear spins are prepolarized in a strong transient field. The magnetic signals generated by the precessing spins, which range in frequency from tens of Hz to several kHz, are detected by a low-transition temperature dc SQUID (Superconducting QUantum Interference Device) coupled to an untuned, superconducting flux transformer configured as an axial gradiometer. The combination of prepolarization and frequency-independent detector sensitivity results in a high signal-to-noise ratio and high spectral resolution (∼1 Hz) even in grossly inhomogeneous magnetic fields. In the NMR experiments, the high spectral resolution enables us to detect the 10-Hz splitting of the spectrum of protons due to their scalar coupling to a 31P nucleus. Furthermore, the broadband detection scheme combined with a non-resonant field-reversal spin echo allows the simultaneous observation of signals from protons and 31P nuclei, even though their NMR resonance frequencies differ by a factor of 2.5. We extend our methodology to MRI in microtesla fields, where the high spectral resolution translates into high spatial resolution. We demonstrate two-dimensional images of a mineral oil phantom and slices of peppers, with a spatial resolution of about 1 mm. We also image an intact pepper using slice selection, again with 1-mm resolution. In further experiments we demonstrate T1-contrast imaging of a water phantom, some parts of which were doped with a paramagnetic salt to reduce the longitudinal relaxation time T1. Possible applications of this MRI technique include screening for tumors and integration with existing multichannel SQUID systems for brain imaging

  1. Waveguide volume probe for magnetic resonance imaging and spectroscopy

    DEFF Research Database (Denmark)

    2015-01-01

    The present disclosure relates to a probe for use within the field of nuclear magnetic resonance, such as magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRS)). One embodiment relates to an RF probe for magnetic resonance imaging and/or spectroscopy comprising a conductive...... non-magnetic hollow waveguide having an internal volume and at least one open end, one or more capacitors and at least a first conductive non-magnetic wire, wherein said first conductive wire connects at least one of said one or more capacitors to opposite walls of one open end of the waveguide...

  2. Slotted cage resonator for high-field magnetic resonance imaging of rodents

    Energy Technology Data Exchange (ETDEWEB)

    Marrufo, O; Vasquez, F; Solis, S E; Rodriguez, A O, E-mail: arog@xanum.uam.mx [Departamento de Ingenieria Electrica, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF 09340 (Mexico)

    2011-04-20

    A variation of the high-frequency cavity resonator coil was experimentally developed according to the theoretical frame proposed by Mansfield in 1990. Circular slots were used instead of cavities to form the coil endplates and it was called the slotted cage resonator coil. The theoretical principles were validated via a coil equivalent circuit and also experimentally with a coil prototype. The radio frequency magnetic field, B1, produced by several coil configurations was numerically simulated using the finite-element approach to investigate their performances. A transceiver coil, 8 cm long and 7.6 cm in diameter, and composed of 4 circular slots with a 15 mm diameter on both endplates, was built to operate at 300 MHz and quadrature driven. Experimental results obtained with the slotted cage resonator coil were presented and showed very good agreement with the theoretical expectations for the resonant frequency as a function of the coil dimensions and slots. A standard birdcage coil was also built for performance comparison purposes. Phantom images were then acquired to compute the signal-to-noise ratio of both coils showing an important improvement of the slotted cage coil over the birdcage coil. The whole-body images of the mouse were also obtained showing high-quality images. Volume resonator coils can be reliably built following the physical principles of the cavity resonator design for high-field magnetic resonance imaging applications of rodents.

  3. Magnetic resonance in temporomandibular articulations

    International Nuclear Information System (INIS)

    Duarte Filho, D.L.; Ferreira, R.

    1994-01-01

    Dysfunction of temporomandibular joint (TMJ) is extremely common, mainly in women. The indication of imaging study of TMJ is the evaluation of its internal derangements, since disc dislocation is treated by different way than other intrinsic mechanical conditions and of the painful myofacial dysfunction, as well where there is no anatomic lesion. The patients, who do not improve with the clinical approach, should be referred to imaging evaluation, in order to rule out mechanical disorder. When the patient is supposed to be operated upon, imaging of the contralateral TMJ is necessary. The presence of a thick and stiff disc perforated with adhesion to the mandibular condyle will change the surgical management. The plain x-ray film is able to demonstrate the bone outlines and joint space but it is not able to show the soft articular tissues. Arthrography is very reliable to demonstrate perforation. However it is an invasive method and demands skilled radiographer radiologist. MRI has shown to be reliable method and it is becoming to be progressively used in routine investigation of TMJ. Nevertheless, MRI still has some limitations concerning to disc perforation. (author). 16 refs, 9 figs

  4. Magnetic resonance imaging of tablet dissolution.

    Science.gov (United States)

    Nott, Kevin P

    2010-01-01

    Magnetic resonance imaging (MRI) is the technique of choice for measuring hydration, and its effects, during dissolution of tablets since it non-invasively maps (1)H nuclei associated with 'mobile' water. Although most studies have used MRI systems with high-field superconducting magnets, low-field laboratory-based instruments based on permanent magnet technology are being developed that provide key data for the formulation scientist. Incorporation of dissolution hardware, in particular the United States Pharmacopeia (USP) apparatus 4 flow-through cell, allows measurements under controlled conditions for comparison against other dissolution methods. Furthermore, simultaneous image acquisition and measurement of drug concentration allow direct comparison of the drug release throughout the hydration process. The combination of low-field MRI with USP-4 apparatus provides another tool to aid tablet formulation. Copyright 2009 Elsevier B.V. All rights reserved.

  5. Nuclear magnetic resonance studies of lipoproteins

    International Nuclear Information System (INIS)

    Hamilton, J.A.; Morrisett, J.D.

    1986-01-01

    Several nuclei in lipoproteins are magnetically active and are thus potential NMR probes of lipoprotein structure. Table I lists the magnetic isotopes preset in the covalent structures of the molecular constituents of lipoproteins: lipids, proteins, and carbohydrates. Every type of nucleus that is part of the endogenous structure of these molecules has at least one magnetic isotope. Each magnetic nucleus represents an intrinsic and completely nonperturbing probe (when at the natural abundance level) of local molecular motion and magnetic environment. The NMR experiment itself is also nonperturbing and nondestructive. Table I also lists for each nucleus its nuclear spin, its natural isotopic abundance, its sensitivity, and its resonance frequency at two commonly employed magnetic in the low field range (21.14 kG or 2.11 Tesla) and the other in the high field range (47.0 kG or 4.70 Tesla). Of the nuclei listed in Table I, /sup 1/H, /sup 13/C, and /sup 31/P have been the primary ones studied in lipoproteins. The general advantages and disadvantages afforded by these and other nuclei as probes of lipoprotein structure are discussed. /sup 13/C NMR spectroscopy, the method which has had the most extensive application (and probably has the greatest future potential) to lipoproteins, is treated in greatest detail, but many of the principles described apply to other nuclei as well

  6. RESONANT ABSORPTION OF AXISYMMETRIC MODES IN TWISTED MAGNETIC FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Giagkiozis, I.; Verth, G. [Solar Plasma Physics Research Centre, School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield, S3 7RH (United Kingdom); Goossens, M.; Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Mappin Street, Amy Johnson Building, Sheffield, S1 3JD (United Kingdom)

    2016-06-01

    It has been shown recently that magnetic twist and axisymmetric MHD modes are ubiquitous in the solar atmosphere, and therefore the study of resonant absorption for these modes has become a pressing issue because it can have important consequences for heating magnetic flux tubes in the solar atmosphere and the observed damping. In this investigation, for the first time, we calculate the damping rate for axisymmetric MHD waves in weakly twisted magnetic flux tubes. Our aim is to investigate the impact of resonant damping of these modes for solar atmospheric conditions. This analytical study is based on an idealized configuration of a straight magnetic flux tube with a weak magnetic twist inside as well as outside the tube. By implementing the conservation laws derived by Sakurai et al. and the analytic solutions for weakly twisted flux tubes obtained recently by Giagkiozis et al. we derive a dispersion relation for resonantly damped axisymmetric modes in the spectrum of the Alfvén continuum. We also obtain an insightful analytical expression for the damping rate in the long wavelength limit. Furthermore, it is shown that both the longitudinal magnetic field and the density, which are allowed to vary continuously in the inhomogeneous layer, have a significant impact on the damping time. Given the conditions in the solar atmosphere, resonantly damped axisymmetric modes are highly likely to be ubiquitous and play an important role in energy dissipation. We also suggest that, given the character of these waves, it is likely that they have already been observed in the guise of Alfvén waves.

  7. Magnetic resonance phenomena in dynamics of relativistic particles

    International Nuclear Information System (INIS)

    Ternov, I.M.; Bordovitsyn, V.A.

    1987-01-01

    A relativistic generalization of Rabi's formula for magnetic resonance is given. On this basis, we consider fast and slow passage through resonance. We define a magnetic resonance exterior field as usual, using unit vectors of a Cartesian coordinate system, a homogeneous magnetic field, and the amplitude of a rotating magnetic field. For the description of spin dynamics we use the Bargmann-Michel-Telegdi equation

  8. Creatine Depletion and Altered Fatty Acid Metabolism in Diseased Human Hearts: Clinical Investigation Using 1H Magnetic Resonance Spectroscopy and 123I BMIPP Myocardial Scintigraphy

    International Nuclear Information System (INIS)

    Nakae, I.; Mitsunami, K.; Matsuo, S.; Horie, M.

    2007-01-01

    Background: In the heart, the creatine kinase system plays an important role in energy reserves, and myocardial energy production essentially depends upon fatty acid metabolism. Purpose: To examine myocardial creatine (CR) concentration and altered cardiac fatty acid metabolism in various forms of heart disease. Material and Methods: Myocardial CR concentration of the septum was measured by gated 1 H magnetic resonance spectroscopy (MRS), applying a point-resolved spectroscopy (PRESS) sequence in 34 patients with heart disease. Of these patients, 14 underwent 123 I BMIPP (radioactive fatty acid analogue) myocardial scintigraphy to evaluate myocardial fatty acid metabolism. Cardiac 123 I BMIPP uptake was calculated as the heart-to-mediastinum count ratio. Results: Myocardial CR concentration correlated positively with the left ventricular ejection fraction (LVEF) by echocardiography (R = 0.61, P 123 I BMIPP uptake also correlated positively with LVEF (initial image, R 0.60, P 123 I BMIPP uptake (initial image, R = 0.77, P<0.01; delayed image, R = 0.82, P<0.001; n = 14). Conclusion: Our study suggests an association between CR depletion and impaired fatty acid metabolism in various forms of heart diseases

  9. Structural investigation of 18-crown-6 complexes of Tri organotin carboxylate by 1H, 13C, 19F and 119Sn nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Foladi, S.; Yousefi, M.; Mohammadpour Ammini, M. M.

    2002-01-01

    Single crystal structure determination of several 18-crown 6 complexes of orga nation derivatives reveals formation of aqua complex through hydrogen bonding to 18-crown-6, which is an important feature in their structure. In the majority of those studies, mono- and dichloro organotin have been used for complexation of them with crown ethers. In the present work, several 18-crown 6 complexes of tri organotin acetate[(C 6 H 5 ) 3 SnOCOCX 3 ] 2 , 18 C6 ], X=F, Cl, and H, have been prepared. The Lewis acidity of tin moiety in tri organotin carboxylate have been tailored by replacing hydrogen atoms of acetate group with chlorine and fluorine and influence of them in the formation of aqua complex with 18 C6 have been studied by infrared. 1 H, 13 C, 19 F and 119 Sn nuclear magnetic resonance spectroscopes. The effects of coordinating and non-coordinating solvent in status of structure in solution have been explored

  10. Nuclear resonance apparatus including means for rotating a magnetic field

    International Nuclear Information System (INIS)

    Sugimoto, H.

    1983-01-01

    A nuclear magnetic resonance apparatus including magnet apparatus for generating a homogeneous static magnetic field between its magnetic poles, shims of a magnetic substance mounted on the magnetic poles to apply a first gradient magnetic field intensity distribution in a direction orthogonal as to the direction of line of magnetic force of the static magnetic field, gradient magnetic field generating electromagnetic apparatus for generating a second gradient magnetic field having a gradient magnetic field intensity distribution in superimposition with the static magnetic field and for changing the magnetic field gradient of the first gradient magnetic field, an oscillator for generating an oscillating output having a frequency corresponding to the nuclear magnetic resonance condition of an atomic nucleus to be measured, a coil wound around a body to be examined for applying the output of said oscillator as electromagnetic waves upon the body, a receiver for detecting the nuclear magnetic resonance signals received by the coil, a gradient magnetic field controller making a magnetic field line equivalent to the combined gradient magnetic fields and for rotating the line along the section of the body to be examined by controlling said gradient magnetic field generating electromagnetic apparatus and devices for recording the nuclear magnetic resonance signals, for reconstructing the concentration distribution of the specific atomic nuclei in the section of the body, and a display unit for depicting the result of reconstruction

  11. Magnetic resonance in medicine occupational exposure to static magnetic field and radiofrequency radiation

    International Nuclear Information System (INIS)

    Zivkovic, D.; Hrnjak, M.; Ivanovic, C.

    1997-01-01

    Medical personnel working with magnetic resonance imaging (MRI) devices could be exposed to static magnetic (M) field, time-varying M fields and radiofrequency (RF) radiation. The aim of work was to investigate the density of magnetic flux of static magnetic field and the power density of RF radiation which appear in the working environment around the 0.5 T MRI unit in one hospital. The density of magnetic flux of static magnetic field was measured with Hall Effect Gauss meter - Magnetech (Great Britain), and the power density of RF radiation was measured with broadband isotropic meter - The Narda Microwave Corp. (USA). The results of measurement show that the density of magnetic flux of static M field on working places are below threshold limit of exposure and the intensities of RF radiation are far below maximum permissible level. (author)

  12. First national meeting of magnetic resonance and hyperfine interactions

    International Nuclear Information System (INIS)

    1985-07-01

    Works performed at CNEA's: Magnetic Resonance Division; Moessbauer Spectroscopy; Solid State Physics Division; Nuclear magnetic Resonance Laboratory and Theoretical Physics Group; Mossbauer Spectroscopy Group; Nuclear Quadrupole Resonance; Physics and Materials Group; Perturbed Angular Correlation and Moessbauer Spectroscopy and Physics Department. (M.E.L.) [es

  13. The particle concentration effect on magnetic resonance linewidth for magnetic liquids with chain aggregates

    International Nuclear Information System (INIS)

    Marin, C.N.

    2002-01-01

    Based on the assumption of particle chains formation within a magnetic liquid, computer simulation of the magnetic resonance line is presented. The dependence on particle concentration within a magnetic liquid of magnetic resonance linewidth is analyzed. The computer simulation demonstrates that the particles chaining has an important effect on the enlargement of the magnetic resonance line. Increasing the particle concentration within magnetic liquid leads to an increase in the linewidth. The agreement with some experimental findings is discussed

  14. Basic principles of magnetic resonance imaging in cerebral ischemia and initial clinical experience

    International Nuclear Information System (INIS)

    Brant-Zawadzki, M.; Solomon, M.; Newton, T.H.; Weinstein, P.; Schmidley, J.; Norman, D.

    1985-01-01

    The basic principles of magnetic resonance imaging are described and their use in the investigation of cerebral ischemia outlined. A brief account is given of the clinical results of investigation to date

  15. Magnetic resonance imaging of spinal cord syndromes

    International Nuclear Information System (INIS)

    Einsiedel, H. von; Stepan, R.

    1985-01-01

    Thirty-four patients with intramedullary space-occupying lesions or cord compression syndromes were examined with a resistive and two different superconductive magnetic resonance (MR) imaging units. Studies were done primarily by the spin-echo (SE) technique and in the majority of patients different pulse sequences were used. Images with short echo-time (TE) and short recovery-time (TR) were best for demonstration of spinal cord anatomy, for depicting cystic portions in intramedullary tumours and for showing syringomyelia. Solid intramedullary tumours showed normal cord signal intensity. Images with prolonged TE and TR predominantly enhanced CSF signal intensity and, to a more considerable extent, solid intramedullary tumours. Thus, the diameter of the subarachnoid space and the presence of a solid intramedullary tumour, not concomittant with a significant enlargement of the spinal cord, could only be recognized on these prolonged SE images. Major advantages of MR in comparison to CT are that the spinal cord can be imaged in the sagittal plane and that beam hardening artifacts do not occur; in comparison to myelography the cord can be imaged directly by MR. Partial volume is a major limitation of MR, not only in the preferably applied sagittal plane. The choice of slice thickness adequate to the diameter of the lesion and straight positioning of the patient for sagittal single slice midline images are fundamental for reliable MR investigations. Another limitation to MR is that cortical bone gives no signal. The actual diameter of the spinal canal therefore cannot be correctly appreciated and consequently it was difficult or impossible to assess spinal stenosis. (orig.)

  16. GEOCHEMICAL CONTROLS ON NUCLEAR MAGNETIC RESONANCE MEASUREMENTS

    International Nuclear Information System (INIS)

    Knight, Rosemary

    2008-01-01

    Proton nuclear magnetic resonance (NMR) is used in the Earth Sciences as a means of obtaining information about the molecular-scale environment of fluids in porous geological materials. Laboratory experiments were conducted to advance our fundamental understanding of the link between the NMR response and the geochemical properties of geological materials. In the first part of this research project, we studied the impact of both the surface-area-to-volume ratio (S/V) of the pore space and the surface relaxivity on the NMR response of fluids in sand-clay mixtures. This study highlighted the way in which these two parameters control our ability to use NMR measurements to detect and quantify fluid saturation in multiphase saturated systems. The second part of the project was designed to explore the way in which the mineralogic form of iron, as opposed to simply the concentration of iron, affects the surface relaxation rate and, more generally, the NMR response of porous materials. We found that the magnitude of the surface relaxation rate was different for the various iron-oxide minerals because of changes in both the surface-area-to-volume ratio of the pore space, and the surface relaxivity. Of particular significance from this study was the finding of an anomalously large surface relaxivity of magnetite compared to that of the other iron minerals. Differences in the NMR response of iron minerals were seen in column experiments during the reaction of ferrihydrite-coated quartz sand with aqueous Fe(II) solutions to form goethite, lepidocrocite and magnetite; indicating the potential use of NMR as a means of monitoring geochemical reactions. The final part of the research project investigated the impact of heterogeneity, at the pore-scale, on the NMR response. This work highlighted the way in which the geochemistry, by controlling the surface relaxivity, has a significant impact on the link between NMR data and the microgeometry of the pore space.

  17. Theoretical study of ferromagnetic resonance in exchange - coupled magnetic / nonmagnetic / magnetic multilayer structure

    International Nuclear Information System (INIS)

    Oezdogan, K.; Oezdemir, M.; Yalcin, O.; Aktas, B.

    2002-01-01

    The dispersion relation on ferromagnetic films was calculation by using torque equation of motion with a damping term. The total energy including zeeman, demagnetizing and anisotropy energy terms was used to get ferromagnetic resonance frequency for both uniform and higher order spin wave modes. In antiferromagnetic films, the torque equation of motion for each sub-lattice were written to derive an expression for the dispersion relation. The magnetic trilayer system under investigation consist of two ferromagnetic layers separated by a nonmagnetic layer. The dispersion relation of magnetic/nonmagnetic/magnetic three layers is calculated by using Landau-Lifshitz dynamic equation of motion for the magnetization with interlayer exchange energy. As for the exchange-coupled resonance of ferromagnetic resonance (FMR), the theoretical study has been calculated for both symmetrical and asymmetrical structures. In this systems, the exchange-coupling parameter A 12 between neighboring layers was used to get resonance fields as a function of the angle between the magnetization vectors of each magnetic layers

  18. Accuracy of magnetic resonance based susceptibility measurements

    Science.gov (United States)

    Erdevig, Hannah E.; Russek, Stephen E.; Carnicka, Slavka; Stupic, Karl F.; Keenan, Kathryn E.

    2017-05-01

    Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Accurate measurements of susceptibility are important for determining oxygen and iron content in blood vessels and brain tissue for use in noninvasive clinical diagnosis and treatment assessments. Induced magnetic fields with amplitude on the order of 100 nT, can be detected using MRI phase images. The induced field distributions can then be inverted to obtain quantitative susceptibility maps. The focus of this research was to determine the accuracy of MRI-based susceptibility measurements using simple phantom geometries and to compare the susceptibility measurements with magnetometry measurements where SI-traceable standards are available. The susceptibilities of paramagnetic salt solutions in cylindrical containers were measured as a function of orientation relative to the static MRI field. The observed induced fields as a function of orientation of the cylinder were in good agreement with simple models. The MRI susceptibility measurements were compared with SQUID magnetometry using NIST-traceable standards. MRI can accurately measure relative magnetic susceptibilities while SQUID magnetometry measures absolute magnetic susceptibility. Given the accuracy of moment measurements of tissue mimicking samples, and the need to look at small differences in tissue properties, the use of existing NIST standard reference materials to calibrate MRI reference structures is problematic and better reference materials are required.

  19. Magnetic resonance, a phenomenon with a great potential in medicine, but with a complex physical background – Part 2: The basics of magnetic resonance

    Directory of Open Access Journals (Sweden)

    Bojan Božič

    2014-01-01

    Full Text Available Magnetic resonance imaging is a very complex diagnostic technique. Therefore, both practical experiences and theoretical understanding is needed for effective diagnostics. It is therefore important that physicians are sufficiently familiar with the basic physical principles of magnetic resonance. In the interpretation of physical concepts, we will rely both on the classical as well as on the quantum-mechanical view of the signal formation in magnetic resonance, which are to some extent complementary. The signal appearance in magnetic resonance imaging will be discussed. A special emphasis will be put on the role of the resonance frequency and the pulse sequences. Furthermore, the spin echo as one of the most used classical signal sequences in diagnostic investigations will be described.

  20. Symmetry adaptation, operator equivalents and magnetic resonance

    International Nuclear Information System (INIS)

    Kibler, M.; Chatterjee, R.

    1977-12-01

    Basic quantities for symmetry adaptation are discussed in connection with molecular and solid state physics. This gives rise to a formalism whose the central elements are operator equivalents adapted to a point group. Such symmetry adapted operator equivalents are defined in terms of Schwinger operators so that they cover the off-diagonal and diagonal cases. Special emphasis is put on the applications of the formalism to magnetic resonance. More specifically, it is shown how to apply the formalism to the construction, the study of the transformation properties, and the determination of the eigenstates of a generalized spin hamiltonian. Numerous examples are given as well as key tables relative to the chain SO(3) for making easy the application of the formalism to electron paramagnetic resonance [fr