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

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

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

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.

Frequency-domain analysis of resonant-type ring magnet power supplies

International Nuclear Information System (INIS)

Kim, J.M.S.; Reiniger, K.W.

1993-01-01

For fast-cycling synchrotrons, resonant-type ring magnet power supplies are commonly used to provide a dc-biased ac excitation for the ring magnets. Up to the present, this power supply system has been analyzed using simplified analytical approximation, namely assuming the resonant frequency of the ring magnet network is fixed and equal to the accelerator frequency. This paper presents a frequency-domain analysis technique for a more accurate analysis of resonant-type ring magnet power supplies. This approach identifies that, with the variation of the resonant frequency, the operating conditions of the power supply changes quite dramatically because of the high Q value of the resonant network. The analytical results are verified, using both experimental results and simulation results

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 ...

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.[...

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 ...

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 ...

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 ...

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

Recent trends in high spin sensitivity magnetic resonance

Science.gov (United States)

Blank, Aharon; Twig, Ygal; Ishay, Yakir

2017-07-01

Magnetic resonance is a very powerful methodology that has been employed successfully in many applications for about 70 years now, resulting in a wealth of scientific, technological, and diagnostic data. Despite its many advantages, one major drawback of magnetic resonance is its relatively poor sensitivity and, as a consequence, its bad spatial resolution when examining heterogeneous samples. Contemporary science and technology often make use of very small amounts of material and examine heterogeneity on a very small length scale, both of which are well beyond the current capabilities of conventional magnetic resonance. It is therefore very important to significantly improve both the sensitivity and the spatial resolution of magnetic resonance techniques. The quest for higher sensitivity led in recent years to the development of many alternative detection techniques that seem to rival and challenge the conventional ;old-fashioned; induction-detection approach. The aim of this manuscript is to briefly review recent advances in the field, and to provide a quantitative as well as qualitative comparison between various detection methods with an eye to future potential advances and developments. We first offer a common definition of sensitivity in magnetic resonance to enable proper quantitative comparisons between various detection methods. Following that, up-to-date information about the sensitivity capabilities of the leading recently-developed detection approaches in magnetic resonance is provided, accompanied by a critical comparison between them and induction detection. Our conclusion from this comparison is that induction detection is still indispensable, and as such, it is very important to look for ways to significantly improve it. To do so, we provide expressions for the sensitivity of induction-detection, derived from both classical and quantum mechanics, that identify its main limiting factors. Examples from current literature, as well as a description of

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 ...

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.

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

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)

Magnetic Resonance Imaging Studies of Postpartum Depression: An Overview

Directory of Open Access Journals (Sweden)

Marco Fiorelli

2015-01-01

Full Text Available Postpartum depression is a frequent and disabling condition whose pathophysiology is still unclear. In recent years, the study of the neural correlates of mental disorders has been increasingly approached using magnetic resonance techniques. In this review we synthesize the results from studies on postpartum depression in the context of structural, functional, and spectroscopic magnetic resonance studies of major depression as a whole. Compared to the relative wealth of data available for major depression, magnetic resonance studies of postpartum depression are limited in number and design. A systematic literature search yielded only eleven studies conducted on about one hundred mothers with postpartum depression overall. Brain magnetic resonance findings in postpartum depression appear to replicate those obtained in major depression, with minor deviations that are not sufficient to delineate a distinct neurobiological profile for this condition, due to the small samples used and the lack of direct comparisons with subjects with major depression. However, it seems reasonable to expect that studies conducted in larger populations, and using a larger variety of brain magnetic resonance techniques than has been done so far, might allow for the identification of neuroimaging signatures for postpartum depression.

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 ...

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 ...

Coil-type Fano Resonances: a Plasmonic Approach to Magnetic Sub-diffraction Confinement

KAUST Repository

Panaro, Simone

2015-05-10

Matrices of nanodisk trimers are introduced as plasmonic platforms for the generation of localized magnetic hot-spots. In Fano resonance condition, the optical magnetic fields can be squeezed in sub-wavelength regions, opening promising scenarios for spintronics.

Coil-type Fano Resonances: a Plasmonic Approach to Magnetic Sub-diffraction Confinement

KAUST Repository

Panaro, Simone; Nazir, Adnan; Zaccaria, Remo Proietti; Liberale, Carlo; De Angelis, Francesco; Toma, Andrea

2015-01-01

Matrices of nanodisk trimers are introduced as plasmonic platforms for the generation of localized magnetic hot-spots. In Fano resonance condition, the optical magnetic fields can be squeezed in sub-wavelength regions, opening promising scenarios for spintronics.

Numerical study of remote detection outside the magnet with travelling wave Magnetic Resonance Imaging at 3T

International Nuclear Information System (INIS)

López, M; Vázquez, F; Solís-Nájera, S; Rodriguez, A O

2015-01-01

The use of the travelling wave approach for high magnetic field magnetic resonance imaging has been used recently with very promising results. This approach offer images one with greater field-of-view and a reasonable signal-to-noise ratio using a circular waveguide. This scheme has been proved to be successful at 7 T and 9.4 T with whole-body imager. Images have also been acquired with clinical magnetic resonance imaging systems whose resonant frequencies were 64 MHz and 128 MHz. These results motivated the use of remote detection of the magnetic resonance signal using a parallel-plate waveguide together with 3 T clinical scanners, to acquired human leg images. The cut-off frequency of this waveguide is zero for the principal mode, allowing us to overcome the barrier of transmitting waves at lower frequency than 300 MHz or 7 T for protons. These motivated the study of remote detection outside the actual magnet. We performed electromagnetic field simulations of a parallel-plate waveguide and a phantom. The signal transmission was done at 128 MHz and using a circular surface coil located almost 200 cm away for the magnet isocentre. Numerical simulations demonstrated that the magnetic field of the principal mode propagate inside a waveguide outside the magnet. Numerical results were compared with previous experimental-acquired image data under similar conditions

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

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,...

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

Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field lines

Science.gov (United States)

Firpo, M.-C.; Constantinescu, D.

2011-03-01

The issue of magnetic confinement in magnetic fusion devices is addressed within a purely magnetic approach. Using some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is shown in a unified way. Away from resonances, it induces a drastic enhancement of magnetic confinement that favors robust internal transport barriers (ITBs) and stochastic transport reduction. When low shear occurs for values of the winding of the magnetic field lines close to low-order rationals, the amplitude thresholds of the resonant modes that break internal transport barriers by allowing a radial stochastic transport of the magnetic field lines may be quite low. The approach can be applied to assess the robustness versus magnetic perturbations of general (almost) integrable magnetic steady states, including nonaxisymmetric ones such as the important single-helicity steady states. This analysis puts a constraint on the tolerable mode amplitudes compatible with ITBs and may be proposed as a possible explanation of diverse experimental and numerical signatures of their collapses.

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.

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

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)

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.

Resonant magnetic scattering of polarized soft x rays

Energy Technology Data Exchange (ETDEWEB)

Sacchi, M. [Centre Universitaire Paris-Sud, Orsay (France); Hague, C.F. [Universite Pierre et Marie Curie, Paris (France); Gullikson, E.M.; Underwood, J. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

1997-04-01

Magnetic effects on X-ray scattering (Bragg diffraction, specular reflectivity or diffuse scattering) are a well known phenomenon, and they also represent a powerful tool for investigating magnetic materials since it was shown that they are strongly enhanced when the photon energy is tuned across an absorption edge (resonant process). The resonant enhancement of the magnetic scattering has mainly been investigated at high photon energies, in order to match the Bragg law for the typical lattice spacings of crystals. In the soft X-ray range, even larger effects are expected, working for instance at the 2p edges of transition metals of the first row or at the 3d edges of rare earths (300-1500 eV), but the corresponding long wavelengths prevent the use of single crystals. Two approaches have been recently adopted in this energy range: (i) the study of the Bragg diffraction from artificial structures of appropriate 2d spacing; (ii) the analysis of the specular reflectivity, which contains analogous information but has no constraints related to the lattice spacing. Both approaches have their own specific advantages: for instance, working under Bragg conditions provides information about the (magnetic) periodicity in ordered structures, while resonant reflectivity can easily be related to electronic properties and absorption spectra. An important aspect common to all the resonant X-ray scattering techniques is the element selectivity inherent to the fact of working at a specific absorption edge: under these conditions, X-ray scattering becomes in fact a spectroscopy. Results are presented for films of iron and cobalt.

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

Vibration-synchronized magnetic resonance imaging for the detection of myocardial elasticity changes.

Science.gov (United States)

Elgeti, Thomas; Tzschätzsch, Heiko; Hirsch, Sebastian; Krefting, Dagmar; Klatt, Dieter; Niendorf, Thoralf; Braun, Jürgen; Sack, Ingolf

2012-04-01

Vibration synchronized magnetic resonance imaging of harmonically oscillating tissue interfaces is proposed for cardiac magnetic resonance elastography. The new approach exploits cardiac triggered cine imaging synchronized with extrinsic harmonic stimulation (f = 22.83 Hz) to display oscillatory tissue deformations in magnitude images. Oscillations are analyzed by intensity threshold-based image processing to track wave amplitude variations over the cardiac cycle. In agreement to literature data, results in 10 volunteers showed that endocardial wave amplitudes during systole (0.13 ± 0.07 mm) were significantly lower than during diastole (0.34 ± 0.14 mm, P magnetic resonance imaging improves the temporal resolution of magnetic resonance elastography as it overcomes the use of extra motion encoding gradients, is less sensitive to susceptibility artifacts, and does not suffer from dynamic range constraints frequently encountered in phase-based magnetic resonance elastography. Copyright © 2012 Wiley Periodicals, Inc.

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

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 ...

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

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

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)

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

A superconducting magnet for whole-body magnetic-resonance imaging

International Nuclear Information System (INIS)

Kan, Hisao; Watanabe, Tsugio; Takechi, Moriaki; Ogino, Osamu; Yamada, Tadatoshi

1986-01-01

Magnetic-resonance imaging is a promising new clinical diagnosis system that employs magnetic resonance to generate cross-sectional images of the object under examination. A large magnet plays a critical role in this system-it must supply a high-strength magnetic field that meets rigid standards of space and time uniformity. Mitsubishi Electric has developed a superconducting magnet that not only offers excellent magnetic characteristics but also features reduced helium consumption and a horizontal service port, and permits direct mounting of a magnetic shield. (author)

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 ( ...

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

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)

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 ...

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.

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 ...

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 ...

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)

Integrated variable projection approach (IVAPA) for parallel magnetic resonance imaging.

Science.gov (United States)

Zhang, Qiao; Sheng, Jinhua

2012-10-01

Parallel magnetic resonance imaging (pMRI) is a fast method which requires algorithms for the reconstructing image from a small number of measured k-space lines. The accurate estimation of the coil sensitivity functions is still a challenging problem in parallel imaging. The joint estimation of the coil sensitivity functions and the desired image has recently been proposed to improve the situation by iteratively optimizing both the coil sensitivity functions and the image reconstruction. It regards both the coil sensitivities and the desired images as unknowns to be solved for jointly. In this paper, we propose an integrated variable projection approach (IVAPA) for pMRI, which integrates two individual processing steps (coil sensitivity estimation and image reconstruction) into a single processing step to improve the accuracy of the coil sensitivity estimation using the variable projection approach. The method is demonstrated to be able to give an optimal solution with considerably reduced artifacts for high reduction factors and a low number of auto-calibration signal (ACS) lines, and our implementation has a fast convergence rate. The performance of the proposed method is evaluated using a set of in vivo experiment data. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

Science.gov (United States)

Vogel, Michael W; Giorni, Andrea; Vegh, Viktor; Pellicer-Guridi, Ruben; Reutens, David C

2016-01-01

We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

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)

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.)

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...

Magnetic resonance imaging in sudden deafness; Ressonancia magnetica em surdez subita

Energy Technology Data Exchange (ETDEWEB)

Ramos, Hugo Valter Lisboa; Barros, Flavia Alencar; Penido, Norma de Oliveira; Souza, Ana Claudia Valerio de; Yamaoka, Wellington Yugo [Sao Paulo Univ., SP (Brazil). Dept. de Otorinolaringologia e Cirurgia da Cabeca e Pescoco; Yamashita, Helio [Sao Paulo Univ., SP (Brazil). Dept. de Imagem e Diagnostico]. E-mail: hvlramos@gmail.com

2005-07-15

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)

[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.

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.

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

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.

Fluoroscopically-Guided Posterior Approach for Shoulder Magnetic Resonance Arthrography: Comparison with Conventional Anterior Approach

International Nuclear Information System (INIS)

Yoo, Koun J.; Ha, Doo Hoe; Lee, Sang Min

2011-01-01

To prospectively evaluate the usefulness of the fluoroscopically-guided posterior approach compared with the anterior approach for shoulder magnetic resonance(MR) arthrography. Institutional review board approval and informed consent were obtained. Among 60 shoulder MR arthrographies performed on 59 patients with symptomatic shoulders, an intra-articular injection was performed (30 cases using the anterior approach and 30 using the posterior approach). Procedure-related pain was assessed by using a 5 score visual analogue scale (VAS). Depth of the puncture and standardized depth of puncture by body mass index (BMI) were recorded. The contrast leakage along the course of the puncture was evaluated by reviewing the MR. The statistical analyses included the Mann-Whitney U and Kruskal-Wallis test. There was no significant difference in VAS scores between the anterior and posterior groups (1.77 ± 1.10 vs. 1.80 ± 0.96). Depth of puncture and standardized depth of puncture by BMI were significantly shorter in the posterior group than those in the anterior group (4.4 ± 0.8 cm and 1.8 ± 0.3 cm vs. 6.6 ± 0.9 cm and 2.8 ± 0.4 cm, p < 0.001), respectively. The incidence of contrast leakage was more frequent in the posterior group (p = 0.003). The posterior approach will be useful in shoulder MR arthrography with a suspected anterior pathology, a postoperative follow-up study or obese patient.

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.

Content Based Retrieval System for Magnetic Resonance Images

International Nuclear Information System (INIS)

Trojachanets, Katarina

2010-01-01

The amount of medical images is continuously increasing as a consequence of the constant growth and development of techniques for digital image acquisition. Manual annotation and description of each image is impractical, expensive and time consuming approach. Moreover, it is an imprecise and insufficient way for describing all information stored in medical images. This induces the necessity for developing efficient image storage, annotation and retrieval systems. Content based image retrieval (CBIR) emerges as an efficient approach for digital image retrieval from large databases. It includes two phases. In the first phase, the visual content of the image is analyzed and the feature extraction process is performed. An appropriate descriptor, namely, feature vector is then associated with each image. These descriptors are used in the second phase, i.e. the retrieval process. With the aim to improve the efficiency and precision of the content based image retrieval systems, feature extraction and automatic image annotation techniques are subject of continuous researches and development. Including the classification techniques in the retrieval process enables automatic image annotation in an existing CBIR system. It contributes to more efficient and easier image organization in the system.Applying content based retrieval in the field of magnetic resonance is a big challenge. Magnetic resonance imaging is an image based diagnostic technique which is widely used in medical environment. According to this, the number of magnetic resonance images is enormously growing. Magnetic resonance images provide plentiful medical information, high resolution and specific nature. Thus, the capability of CBIR systems for image retrieval from large database is of great importance for efficient analysis of this kind of images. The aim of this thesis is to propose content based retrieval system architecture for magnetic resonance images. To provide the system efficiency, feature

Examination of the role of magnetic resonance imaging in multiple sclerosis: A problem-orientated approach

Directory of Open Access Journals (Sweden)

McFarland Henry

2009-01-01

Full Text Available Magnetic Resonance Imaging (MRI has brought in several benefits to the study of Multiple Sclerosis (MS. It provides accurate measurement of disease activity, facilitates precise diagnosis, and aid in the assessment of newer therapies. The imaging guidelines for MS are broadly divided in to approaches for imaging patients with suspected MS or clinically isolated syndromes (CIS or for monitoring patients with established MS. In this review, the technical aspects of MR imaging for MS are briefly discussed. The imaging process need to capture the twin aspects of acute MS viz. the autoimmune acute inflammatory process and the neurodegenerative process. Gadolinium enhanced MRI can identify acute inflammatory lesions precisely. The commonly applied MRI marker of disease progression is brain atrophy. Whole brain magnetization Transfer Ratio (MTR and Magnetic Resonance Spectroscopy (MRS are two other techniques use to monitor disease progression. A variety of imaging techniques such as Double Inversion Recovery (DIR, Spoiled Gradient Recalled (SPGR acquisition, and Fluid Attenuated Inversion Recovery (FLAIR have been utilized to study the cortical changes in MS. MRI is now extensively used in the Phase I, II and III clinical trials of new therapies. As the technical aspects of MRI advance rapidly, and higher field strengths become available, it is hoped that the impact of MRI on our understanding of MS will be even more profound in the next decade.

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)

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

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)

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.

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....

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....

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.

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

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.)

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.

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

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 ...

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 ...

Torsional resonance mode magnetic force microscopy: enabling higher lateral resolution magnetic imaging without topography-related effects

International Nuclear Information System (INIS)

Kaidatzis, A; García-Martín, J M

2013-01-01

We present experimental work that reveals the benefits of performing magnetic force microscopy measurements employing the torsional resonance mode of cantilever oscillation. This approach provides two clear advantages: the ability of performing magnetic imaging without topography-related interference and the significant lateral resolution improvement (approximately 15%). We believe that this work demonstrates a significant improvement to a versatile magnetic imaging technique widely used in academia and in industry. (paper)

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

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

Wake-Field Wave Resonant Excitation in Magnetized Plasmas by Electromagnetic Pulse

International Nuclear Information System (INIS)

Milant'ev, V.P.; Turikov, V.A.

2006-01-01

In this paper the space charge wave excitation process at electromagnetic pulse propagation along external magnetic field in vicinity of electron cyclotron resonance. In hydrodynamic approach it is obtained an equation for plasma density under ponderomotive force action. With help of this equation we investigated a wake-field wave amplitude dependence from resonance detuning. The numerical simulation using a PIC method electromagnetic pulse propagation process in the resonant conditions was done

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 ...

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.

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.

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.

Magnetic Resonance Imaging to Visualize Disintegration of Oral Formulations.

Science.gov (United States)

Curley, Louise; Hinton, Jordan; Marjoribanks, Cameron; Mirjalili, Ali; Kennedy, Julia; Svirskis, Darren

2017-03-01

This article demonstrates that magnetic resonance imaging can visualize the disintegration of a variety of paracetamol containing oral formulations in an in vitro setting and in vivo in the human stomach. The different formulations had unique disintegration profiles which could be imaged both in vitro and in vivo. No special formulation approaches or other contrast agents were required. These data demonstrate the potential for further use of magnetic resonance imaging to investigate and understand the disintegration behavior of different formulation types in vivo, and could potentially be used as a teaching tool in pharmaceutical and medical curricula. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

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

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

Magnetic resonance imaging in clinically-definite multiple sclerosis

International Nuclear Information System (INIS)

Noakes, J.B.; Herkes, G.K.; Frith, J.A.

1990-01-01

Forty-two patients with clinically-definite multiple sclerosis were examined by magnetic resonance imaging using a 1.5-T instrument. Magnetic resonance imaging detected an abnormality in 90% of patients. In four patients, no lesions were demonstrated. The number, size and site of the lesions by magnetic resonance imaging were compared with the patients' clinical status and other variables. The Kurtzke disability status scale score increased in patients with corpus callosum atrophy, brainstem and basal ganglia lesions, and correlated with the total number of lesions. No correlation was shown between the findings of magnetic resonance imaging and disease duration, age, sex or pattern-reversal visual-evoked potentials. The variety of magnetic resonance images that could be obtained in patients with clinically-definite multiple sclerosis is highlighted. 24 refs., 8 figs., 1 tab

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)

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.

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.

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.

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)

Dipole and quadrupole magnetic resonances in nuclei of Ni isotopes

International Nuclear Information System (INIS)

Goncharova, N.G.; Mishchenko, G.M.; Ehramzhyan, R.A.

1982-01-01

Basing on a microscopic approach to the nuclear shell model, magnetic resonances following the electron excitation of the 58 Ni and 60 Ni nuclei are considered. 0h/2π#betta# and 2h/2π#betta#-transitions are taken into accoun for the M1-excitations. For the M2-states, transitions to the next shell are considered only. For the magnetic excitations the form factors and electron-excitation cross sections are calculated, and the effect of the lower 2 1+ , 2 2+ , 3 - , 4 + phonon excitations on the position and structure of the M1- and M2-resonances is traced. +he energies and mean equilibrium deformations are presented for the phonons taken into account. The structure and position of the main magnetic resonance maxima, in difference with the giant dipole resonance in photoabsorption, have proven to be weakly dependent on the isotope choice. For the M1-resonance this effect is related with the fact that the lower excitation states, located in the energy range E 60 Ni and 58 Ni, respectively. A strongly collectivized state, acquiring a notable strength of the M-1 transitions, is located at approximately 32 MeV. The form factor for this level attains the maximum at q=160-190 MeV/c

Resonance of magnetization excited by voltage in magnetoelectric heterostructures

Science.gov (United States)

Yu, Guoliang; Zhang, Huaiwu; Li, Yuanxun; Li, Jie; Zhang, Dainan; Sun, Nian

2018-04-01

Manipulation of magnetization dynamics is critical for spin-based devices. Voltage driven magnetization resonance is promising for realizing low-power information processing systems. Here, we show through Finite Element Method (FEM) simulations that magnetization resonance in nanoscale magnetic elements can be generated by a radio frequency (rf) voltage via the converse magnetoelectric (ME) effect. The magnetization dynamics induced by voltage in a ME heterostructures is simulated by taking into account the magnetoelastic and piezoelectric coupling mechanisms among magnetization, strain and voltage. The frequency of the excited magnetization resonance is equal to the driving rf voltage frequency. The proposed voltage driven magnetization resonance excitation mechanism opens a way toward energy-efficient spin based device applications.

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

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...

Observation of ferromagnetic resonance in a microscopic sample using magnetic resonance force microscopy

International Nuclear Information System (INIS)

Zhang, Z.; Hammel, P.C.; Wigen, P.E.

1996-01-01

We report the observation of a ferromagnetic resonance signal arising from a microscopic (∼20μmx40μm) particle of thin (3μm) yttrium iron garnet film using magnetic resonance force microscopy (MRFM). The large signal intensity in the resonance spectra suggests that MRFM could become a powerful microscopic ferromagnetic resonance technique with a micron or sub-micron resolution. We also observe a very strong nonresonance signal which occurs in the field regime where the sample magnetization readily reorients in response to the modulation of the magnetic field. This signal will be the main noise source in applications where a magnet is mounted on the cantilever. copyright 1996 American Institute of Physics

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

AIR-MRF: Accelerated iterative reconstruction for magnetic resonance fingerprinting.

Science.gov (United States)

Cline, Christopher C; Chen, Xiao; Mailhe, Boris; Wang, Qiu; Pfeuffer, Josef; Nittka, Mathias; Griswold, Mark A; Speier, Peter; Nadar, Mariappan S

2017-09-01

Existing approaches for reconstruction of multiparametric maps with magnetic resonance fingerprinting (MRF) are currently limited by their estimation accuracy and reconstruction time. We aimed to address these issues with a novel combination of iterative reconstruction, fingerprint compression, additional regularization, and accelerated dictionary search methods. The pipeline described here, accelerated iterative reconstruction for magnetic resonance fingerprinting (AIR-MRF), was evaluated with simulations as well as phantom and in vivo scans. We found that the AIR-MRF pipeline provided reduced parameter estimation errors compared to non-iterative and other iterative methods, particularly at shorter sequence lengths. Accelerated dictionary search methods incorporated into the iterative pipeline reduced the reconstruction time at little cost of quality. Copyright © 2017 Elsevier Inc. All rights reserved.

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...

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 ...

Functional magnetic resonance imaging with ultra-high fields

International Nuclear Information System (INIS)

Windischberger, C.; Schoepf, V.; Sladky, R.; Moser, E.; Fischmeister, F.P.S.

2010-01-01

Functional magnetic resonance imaging (fMRI) is currently the primary method for non-invasive functional localization in the brain. With the emergence of MR systems with field strengths of 4 Tesla and above, neuronal activation may be studied with unprecedented accuracy. In this article we present different approaches to use the improved sensitivity and specificity for expanding current fMRT resolution limits in space and time based on several 7 Tesla studies. In addition to the challenges that arise with ultra-high magnetic fields possible solutions will be discussed. (orig.) [de

Resonant tunnel magnetoresistance in a double magnetic tunnel junction

KAUST Repository

Useinov, Arthur

2011-08-09

We present quasi-classical approach to calculate a spin-dependent current and tunnel magnetoresistance (TMR) in double magnetic tunnel junctions (DMTJ) FML/I/FMW/I/FMR, where the magnetization of the middle ferromagnetic metal layer FMW can be aligned parallel or antiparallel with respect to the fixed magnetizations of the left FML and right FMR ferromagnetic electrodes. The transmission coefficients for components of the spin-dependent current, and TMR are calculated as a function of the applied voltage. As a result, we found a high resonant TMR. Thus, DMTJ can serve as highly effective magnetic nanosensor for biological applications, or as magnetic memory cells by switching the magnetization of the inner ferromagnetic layer FMW.© Springer Science+Business Media, LLC 2011.

Magnetic resonance angiography for the head and neck region

International Nuclear Information System (INIS)

Aschenbach, R.; Esser, D.

2004-01-01

Magnetic resonance angiography is a noninvasive method in vascular imaging using noncontrast- enhanced and contrast-enhanced techniques. The contrast media used in contrast- enhanced magnetic resonance angiography are different from the X-ray contrast media and do not affect the thyroid gland or renal function. In detecting hypervascularized lesions in the head and neck, contrast-enhanced magnetic resonance angiography is the method of choice, which provides an acceptable quality in comparison to digital subtraction angiography. Future developments in magnetic resonance imaging techniques will cause a wider use of magnetic resonance angiography, especially in head and neck imaging. Digital subtraction angiography should therefore only be used in problem cases and for preoperative embolization [de

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 ...

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 ...

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

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)

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

Pulse sequences for contrast-enhanced magnetic resonance imaging

International Nuclear Information System (INIS)

Graves, Martin J.

2007-01-01

The theory and application of magnetic resonance imaging (MRI) pulse sequences following the administration of an exogenous contrast agent are discussed. Pulse sequences are categorised according to the contrast agent mechanism: changes in proton density, relaxivity, magnetic susceptibility and resonant frequency shift. Applications in morphological imaging, magnetic resonance angiography, dynamic imaging and cell labelling are described. The importance of optimising the pulse sequence for each application is emphasised

Magnetic field induced incommensurate resonance in cuprate superconductors

International Nuclear Information System (INIS)

Zhang Jingge; Cheng Li; Guo Huaiming; Feng Shiping

2009-01-01

The influence of a uniform external magnetic field on the dynamical spin response of cuprate superconductors in the superconducting state is studied based on the kinetic energy driven superconducting mechanism. It is shown that the magnetic scattering around low and intermediate energies is dramatically changed with a modest external magnetic field. With increasing the external magnetic field, although the incommensurate magnetic scattering from both low and high energies is rather robust, the commensurate magnetic resonance scattering peak is broadened. The part of the spin excitation dispersion seems to be an hourglass-like dispersion, which breaks down at the heavily low energy regime. The theory also predicts that the commensurate resonance scattering at zero external magnetic field is induced into the incommensurate resonance scattering by applying an external magnetic field large enough

Inhalant-Abuse Myocarditis Diagnosed by Cardiac Magnetic Resonance.

Science.gov (United States)

Dinsfriend, William; Rao, Krishnasree; Matulevicius, Susan

2016-06-01

Multiple reports of toxic myocarditis from inhalant abuse have been reported. We now report the case of a 23-year-old man found to have toxic myocarditis from inhalation of a hydrocarbon. The diagnosis was made by means of cardiac magnetic resonance imaging with delayed enhancement. The use of cardiac magnetic resonance to diagnose myocarditis has become increasingly common in clinical medicine, although there is not a universally accepted criterion for diagnosis. We appear to be the first to document a case of toxic myocarditis diagnosed by cardiac magnetic resonance. In patients with a history of drug abuse who present with clinical findings that suggest myocarditis or pericarditis, cardiac magnetic resonance can be considered to support the diagnosis.

Magnetic resonance imaging- physical principles and clinical application

International Nuclear Information System (INIS)

Tavri, Omprakash J.

1996-01-01

The advances in equipment and knowledge related to radiology are occurring at an astonishingly rapid rate. On November 8, 1895, William Conrad Roentgen discovered x-rays. In 1972, Godfrey Hounsfield and George Ambrose introduced computec tomography at a meeting of the British Institute of Radiology. In the same year, Paul Lauterbur published the idea of spatially resolving nuclear magnetic resonance samples, naming it zeugmatography. In 1977, Waldo Hinshaw and co-workers published a magnetic resonance image of a human hand and wrist, and by 1981 several centres were obtaining clinical magnetic resonance (MR) images. In a very short time, magnetic resonance imaging (MRI) has gained acceptance as a clinically useful imaging tool. (author)

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.

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 ...

Tuning Coler Magnetic Current Apparatus with Magneto-Acoustic Resonance

Science.gov (United States)

Ludwig, Thorsten

An attempt was made to tune the Coler magnetic current apparatus with the magneto acoustic resonance of the magnetic rods. Measurements with a replica of the famous Coler "Magnetstromapparat" were conducted. In order to tune the acoustic, magnetic and electric resonance circuits of the Coler device the magneto-acoustic resonance was measured with a frequency scan through a function generator and a lock-in amplifier. The frequency generator was powering a driving coil, while the lock-in was connected to a pickup coil. Both coils were placed on a magnetic rod. Resonances were observed up to the 17th harmonic. The quality Q of the observed resonances was 270. To study the magneto-acoustic resonance in the time domain a pair of Permendur rods were employed. The magneto-acoustic resonances of the Permendur rods were observed with an oscilloscope. Spectra of the magneto acoustic resonance were measured for the Permendur rods and for a Coler replica magnet in the frequency range from 25 kHz to 380 kHz. The next step was to bring the resonances of the Permendur rods close together so that they overlap. The 10thharmonic was chosen because it was close to the 180 kHz that Hans Coler related to ferromagnetism. Further more magneto-acoustic coupling between the Permendur rods was studied. Finally the question was explored if Hans Coler converted vacuum fluctuations via magnetic and acoustic resonance into electricity. There is a strong connection between magnetism and quantum field zero point energy (ZPE). An outlook is given on next steps in the experiments to unveil the working mechanism of the Coler magnetic current apparatus.

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...

Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

Energy Technology Data Exchange (ETDEWEB)

Morii, Y.; Sukedai, M. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

2011-11-15

The hybrid magnetic bearing has been developed. In the hybrid system, effect of the pinning force becomes smaller. Influence of the vibration and the gradient angle in the resonance state is large. The resonance frequency becomes small in the hybrid bearing system. The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

Characterization of human breast disease using phosphorus magnetic resonance spectroscopy and proton magnetic resonance imaging

International Nuclear Information System (INIS)

Merchant, T.E.

1992-01-01

This thesis provides the fundamental characterization and differentiation of breast tissues using in vivo and ex vivo MR techniques in the hope that these techniques and experimental findings will be used on a larger scale and in a predictive manner in order to improve the specificity of diagnosis and treatment of breast cancer. In this dissertation, clinical studies were performed using proton magnetic resonance imaging and phosphorus magnetic resonance spectro-scopy ( 31 P MRS) to characterize and differentiate malignant breast tumors, benign breast tumors and normal breast tissues in vivo. These studies were carried out following the methodical characterization of chemical extracts of malignant breast tumor, benign breast tumor and normal breast parenchymal surgical tissue specimens using high resolution 31 P MRS. Alterations in breast tissue metabolism, as a result of pathological processes, were postulated to be responsible for measurable differences between malignant breast tumors, benign breast tumors and normal breast tissues using magnetic resonance techniques. (author). 365 refs.; 37 figs.; 25 tabs

Effects of lymphatic drainage on cellulitis assessed by magnetic resonance

International Nuclear Information System (INIS)

Meyer, Patricia Froes; Martins, Nara Mendes; Martins, Flavia Mendes; Monteiro, Rosimary Araujo; Mendonca, Karla Morganna Pereira Pinto de

2008-01-01

The aim of this study was to assess the use of magnetic resonance as a new method for evaluating the manual lymphatic drainage technique in treating cellulitis. Cellulitis is one of the main esthetic problems that lead women toward seeking guidance and specific treatments. There are various therapeutic approaches, owing to the multifactorial nature of its pathogen, although the effectiveness of most of these has not been definitively proven, given that the assessment methods used are mostly subjective or do not provide enough information on subcutaneous tissue. The introduction of magnetic resonance as a means of assessing a lymphatic drainage technique in cellulitis treatment makes the evaluation more accurate, since it enables a detailed study of subcutaneous architecture. (author)

Effects of lymphatic drainage on cellulitis assessed by magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Meyer, Patricia Froes; Martins, Nara Mendes; Martins, Flavia Mendes; Monteiro, Rosimary Araujo; Mendonca, Karla Morganna Pereira Pinto de [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Ciencias da Saude

2008-12-15

The aim of this study was to assess the use of magnetic resonance as a new method for evaluating the manual lymphatic drainage technique in treating cellulitis. Cellulitis is one of the main esthetic problems that lead women toward seeking guidance and specific treatments. There are various therapeutic approaches, owing to the multifactorial nature of its pathogen, although the effectiveness of most of these has not been definitively proven, given that the assessment methods used are mostly subjective or do not provide enough information on subcutaneous tissue. The introduction of magnetic resonance as a means of assessing a lymphatic drainage technique in cellulitis treatment makes the evaluation more accurate, since it enables a detailed study of subcutaneous architecture. (author)

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)

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 ...

Magnetic resonance imaging of the central nervous system

International Nuclear Information System (INIS)

Brant-Zawadzki, M.; Norman, D.

1987-01-01

This book presents the papers on technological advancement and diagnostic uses g magnetic resonance imaging. A comparative evaluation with computerized tomography is presented. Topics covered are imaging principles g magnetic resonance;instrumentation of magnetic resonance (MR);pathophysiology;quality and limitations g images;NMR imaging of brain and spinal cord;MR spectroscopy and its applications;neuroanatomy;Congenital malformations of brain and MR imaging;planning g MR imaging of spine and head and neck imaging

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)

Intensity-Curvature Measurement Approaches for the Diagnosis of Magnetic Resonance Imaging Brain Tumors

Directory of Open Access Journals (Sweden)

Carlo Ciulla

2015-11-01

Full Text Available This research presents signal-image post-processing techniques called Intensity-Curvature Measurement Approaches with application to the diagnosis of human brain tumors detected through Magnetic Resonance Imaging (MRI. Post-processing of the MRI of the human brain encompasses the following model functions: (i bivariate cubic polynomial, (ii bivariate cubic Lagrange polynomial, (iii monovariate sinc, and (iv bivariate linear. The following Intensity-Curvature Measurement Approaches were used: (i classic-curvature, (ii signal resilient to interpolation, (iii intensity-curvature measure and (iv intensity-curvature functional. The results revealed that the classic-curvature, the signal resilient to interpolation and the intensity-curvature functional are able to add additional information useful to the diagnosis carried out with MRI. The contribution to the MRI diagnosis of our study are: (i the enhanced gray level scale of the tumor mass and the well-behaved representation of the tumor provided through the signal resilient to interpolation, and (ii the visually perceptible third dimension perpendicular to the image plane provided through the classic-curvature and the intensity-curvature functional.

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

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 ...

Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fonte, Mariana Vieira de Melo da; Otaduy, Maria Concepcion Garcia; Lucato, Leandro Tavares; Reed, Umbertina Conti; Leite, Claudia da Costa [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Inst. de Radiologia]. E-mail: mvmfonte@uol.com.br; Costa, Maria Olivia Rodrigues; Amaral, Raquel Portugal Guimaraes [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Radiologia; Reed, Umbertina Conti [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Neurologia; Rosemberg, Sergio [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Dept. de Patologia

2008-11-15

To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumors characteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, and diffusion-weighted imaging and spectroscopy findings. In most of cases the tumors were centered in the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T 1-weighted images and intermediate/hyperintense on T 2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquired with STEAM technique (n = 6) demonstrated decreased Na a / Cr ratio (83.3%) and increased Co/Cr (100%) and ml/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. (author)

Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Fonte, Mariana Vieira de Melo da; Otaduy, Maria Concepcion Garcia; Lucato, Leandro Tavares; Reed, Umbertina Conti; Leite, Claudia da Costa; Costa, Maria Olivia Rodrigues; Amaral, Raquel Portugal Guimaraes; Reed, Umbertina Conti; Rosemberg, Sergio

2008-01-01

To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumors characteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, and diffusion-weighted imaging and spectroscopy findings. In most of cases the tumors were centered in the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T 1-weighted images and intermediate/hyperintense on T 2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquired with STEAM technique (n = 6) demonstrated decreased Na a / Cr ratio (83.3%) and increased Co/Cr (100%) and ml/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. (author)

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)

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? ...

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.)

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)

Gyrokinetic theory of perpendicular cyclotron resonance in a nonuniformly magnetized plasma

International Nuclear Information System (INIS)

Lashmore-Davies, C.N.; Dendy, R.O.

1989-01-01

The extension of gyrokinetic theory to arbitrary frequencies by Chen and Tsai [Phys. Fluids 26, 141 (1983); Plasma Phys. 25, 349 (1983)] is used to study cyclotron absorption in a straight magnetic field with a perpendicular, linear gradient in strength. The analysis includes the effects of magnetic field variation across the Larmor orbit and is restricted to propagation perpendicular to the field. It yields the following results for propagation into the field gradient. The standard optical depths for the fundamental O-mode and second harmonic X-mode resonances are obtained from the absorption profiles given in this paper, without invoking relativistic mass variation [see also Antonsen and Manheimer, Phys. Fluids 21, 2295 (1978)]. The compressional Alfven wave is shown to undergo perpendicular cyclotron damping at the fundamental minority resonance in a two-ion species plasma and at second harmonic resonance in a single-ion species plasma. Ion Bernstein waves propagating into the second harmonic resonance are no longer unattenuated, but are increasingly damped as they approach the resonance. It is shown how the kinetic power flow affects absorption profiles, yielding information previously obtainable only from full-wave theory. In all cases, the perpendicular cyclotron damping arises from the inclusion of magnetic field variation across the Larmor orbit

Evaluation of urogenital fistulas by magnetic resonance urography

International Nuclear Information System (INIS)

Mamere, Augusto Elias; Coelho, Rafael Darahem Souza; Cecin, Alexandre Oliveira; Feltrin, Leonir Terezinha; Lucchesi, Fabiano Rubiao; Seabra, Daniel

2008-01-01

Objective: Vesicovaginal and ureterovaginal fistulas are unusual complications secondary to pelvic surgery or pelvic diseases. The therapeutic success in these cases depends on an appropriate preoperative evaluation for diagnosis and visualization of the fistulous tract. The present study is aimed at demonstrating the potential of magnetic resonance urography for the diagnosis of vesicovaginal and ureterovaginal fistulas as well as for defining the fistulous tracts. Materials And Methods: Seven female patients clinically diagnosed with vesicovaginal or ureterovaginal fistulas had their medical records, radiological and magnetic resonance images retrospectively reviewed. Magnetic resonance urography included 3D-HASTE sequences with fat saturation. Results: Six patients presented vesicovaginal fistulas and, in one patient, a right-sided ureterovaginal fistula was diagnosed. Magnetic resonance urography allowed the demonstration of the fistulous tract in six (85.7%) of the seven patients evaluated in the present study, without the need of bladder catheterization or contrast injection. Conclusion: This study demonstrates both the potential and applicability of magnetic resonance urography in the evaluation of these types of fistulas. (author)

Object-oriented magnetic resonance classes and objects, calculations and computations

CERN Document Server

Mehring, Michael

2001-01-01

This book presents, for the first time, a unified treatment of the quantum mechanisms of magnetic resonance, including both nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Magnetic resonance is perhaps the most advanced type of spectroscopy and it is applied in biology, chemistry, physics, material science, and medicine. If applied in conjunction with spectroscopy, the imaging version of magnetic resonance has no counterpart in any type of experimental technique. The authors present explanations and applications from fundamental to advanced levels. Additionally, the

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.

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

Atomic-resolution single-spin magnetic resonance detection concept based on tunneling force microscopy

Science.gov (United States)

Payne, A.; Ambal, K.; Boehme, C.; Williams, C. C.

2015-05-01

A study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single-electron tunneling between two electrically isolated paramagnetic states. Single-spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured atomic force microscopy system noise. The results show that the approach could provide single-spin measurement of electrically isolated qubit states with atomic spatial resolution at room temperature.

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

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)

In Vivo Imaging of Nitric Oxide by Magnetic Resonance Imaging Techniques

Directory of Open Access Journals (Sweden)

Rakesh Sharma

2014-01-01

Full Text Available Nitric oxide (NO biosensors are novel tools for real-time bioimaging of tissue oxygen changes and physiological monitoring of tissue vasculature. Nitric oxide behavior further enhances its role in mapping signal transduction at the molecular level. Spectrometric electron paramagnetic resonance (EPR and fluorometric imaging are well known techniques with the potential for in vivo bioimaging of NO. In tissues, NO is a specific target of nitrosyl compounds for chemical reaction, which provides a unique opportunity for application of newly identified NO biosensors. However, the accuracy and sensitivity of NO biosensors still need to be improved. Another potential magnetic resonance technique based on short term NO effects on proton relaxation enhancement is magnetic resonance imaging (MRI, and some NO biosensors may be used as potent imaging contrast agents for measurement of tumor size by MRI combined with fluorescent imaging. The present review provides supporting information regarding the possible use of nitrosyl compounds as NO biosensors in MRI and fluorescent bioimaging showing their measurement limitations and quantitative accuracy. These new approaches open a perspective regarding bioimaging of NO and the in vivo elucidation of NO effects by magnetic resonance techniques.

Broadband and Resonant Approaches to Axion Dark Matter Detection.

Science.gov (United States)

Kahn, Yonatan; Safdi, Benjamin R; Thaler, Jesse

2016-09-30

When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10^{-14}-10^{-6}  eV. In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

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

Magnetic resonance of native defects of spin-Peierls magnetics CuGeO3

International Nuclear Information System (INIS)

Smirnov, A.I.; Glazkov, V.N.; Leonyuk, L.I.; Vetkin, A.G.; Eremina, R.M.

1998-01-01

Magnetic resonance within 9-75 GHz frequency range and 1.2-25 K temperature range was studied in pure monocrystalline spin-Peierls CuGwO 3 . Splitting of the magnetic resonance line is observed within temperature range below 5 K. Analysis of magnetic resonance spectra at various directions of magnetic field and under various temperatures enables to set off EPR-signals of spin-Peierls phase defects with S=1/2 and defects with S=1 from these components; g-factor corresponding to these EPR signals is similar one and close to values typical for Cu 2+ ion [ru

Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

International Nuclear Information System (INIS)

Paulsen, Jeffrey L; Franck, John; Demas, Vasiliki; Bouchard, Louis-S.

2008-01-01

Single-sided and mobile nuclear magnetic resonance (NMR) sensors have the advantages of portability, low cost, and low power consumption compared to conventional high-field NMR and magnetic resonance imaging (MRI) systems. We present fast, flexible, and easy-to-implement target field algorithms for mobile NMR and MRI magnet design. The optimization finds a global optimum in a cost function that minimizes the error in the target magnetic field in the sense of least squares. When the technique is tested on a ring array of permanent-magnet elements, the solution matches the classical dipole Halbach solution. For a single-sided handheld NMR sensor, the algorithm yields a 640 G field homogeneous to 16,100 ppm across a 1.9 cc volume located 1.5 cm above the top of the magnets and homogeneous to 32,200 ppm over a 7.6 cc volume. This regime is adequate for MRI applications. We demonstrate that the homogeneous region can be continuously moved away from the sensor by rotating magnet rod elements, opening the way for NMR sensors with adjustable 'sensitive volumes'

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)

Magnetic resonance in prenatal diagnosis of thoracic anomalies

International Nuclear Information System (INIS)

Pietrani, M.; Elias, D.; Wojakowski, A.; Fataljaef, V.; Carcano, M.; Otano, L.

2007-01-01

The objective of this article is to communicate the experience in the evaluation of fetal anomalies thoracic by means of magnetic resonance. Between January, 2001 - March, 2007 16 fetus were evaluated by means of magnetic resonance with echographic diagnosis of thoracic anomalies. An equipment of 1.5 TESLA was used. The thoracic anatomy was valued in general. At the presence of discovering pulmonary mass, their size, volume and intensity of sign were determined. The echographic and magnetic resonance findings were checked against the perinatal results [es

Role of chelates in magnetic resonance imaging studies

Directory of Open Access Journals (Sweden)

Tripathi Laxmi

2009-01-01

Full Text Available Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient′s body. Magnetic resonance imaging (MRI is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media.

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.)

A Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

OpenAIRE

Berman, G. P.; Doolen, G. D.; Tsifrinovich, V. I.

2000-01-01

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines the well-developed silicon technology with expected advances in MRFM.

Magnetic resonance imaging of valvular heart disease

DEFF Research Database (Denmark)

Søndergaard, Lise; Ståhlberg, F; Thomsen, C

1999-01-01

The optimum management of patients with valvular heart diseases requires accurate and reproducible assessment of the valvular lesion and its hemodynamic consequences. Magnetic resonance imaging (MRI) techniques, such as volume measurements, signal-void phenomena, and velocity mapping, can be used...... in an integrated approach to gain qualitative and quantitative information on valvular heart disease as well as ventricular dimensions and functions. Thus, MRI may be advantageous to the established diagnostic tools in assessing the severity of valvular heart disease as well as monitoring the lesion and predicting...... the optimal timing for valvular surgery. This paper reviews the validation of these MRI techniques in assessing valvular heart disease and discusses some typical pitfalls of the techniques, including suggestions for solutions.J. Magn. Reson. Imaging 1999;10:627-638....

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)

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).

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

Parenchymal abnormalities in cerebral venous thrombosis: findings of magnetic resonance imaging and magnetic resonance angiography

International Nuclear Information System (INIS)

Ferreira, Clecia Santos; Pellini, Marcos; Boasquevisque, Edson; Souza, Luis Alberto M. de

2006-01-01

Objective: to determine the frequency and localization of parenchymal abnormalities in cerebral venous thrombosis on magnetic resonance imaging and magnetic resonance angiography as well as their correlation with the territory and affected venous drainage. Materials and methods: retrospective analysis (1996 to 2004) of 21 patients (3 male and 18 female) age range between 3 and 82 years (mean 40 years, median 36 years) with clinical and radiological diagnosis of cerebral venous thrombosis on magnetic resonance imaging and magnetic resonance angiography in 2D PC, 3D PC and contrast-enhanced 3D TOF sequences. The statistical analysis was performed with the qui-square test. Four patients had follow-up exams and three patients underwent digital subtraction angiography. Results: main predisposing factors were: infection, use of oral contraceptives, hormone replacement therapy and collagenosis. Predominant symptoms included: focal deficit, headache, alteration of consciousness level and seizures. Most frequent parenchymal manifestations were: cortical/subcortical edema or infarct, venous congestion and collateral circulation, meningeal enhancement and thalamic and basal ganglia edema or infarct. Occlusion occurred mainly in superior sagittal, left transverse, left sigmoid and straight sinuses. Cavernous sinus and cortical veins thrombosis are uncommon events. Conclusion: cerebral venous thrombosis is an uncommon cause of stroke, with favorable prognosis because of its reversibility. Diagnosis is highly dependent on the radiologist capacity to recognize the presentations of this disease, principally in cases where the diagnosis is suggested by parenchymal abnormalities rather than necessarily by visualization of the thrombus itself. An accurate and rapid diagnosis allows an immediate treatment, reducing the morbidity and mortality rates. (author)

Nuclear magnetic resonance spectroscopy in organic chemistry. 2. ed.

International Nuclear Information System (INIS)

Zschunke, A.

1977-01-01

The fundamentals of nuclear magnetic resonance spectroscopy are discussed only briefly. The emphasis is laid on developing reader's ability to evaluate resonance spectra. The following topics are covered: principles of nuclear magnetic resonance spectroscopy; chemical shift and indirect nuclear spin coupling constants and their relation to the molecular structure; analysis of spectra; and uses for structural analysis and solution of kinetic problems, mainly with regard to organic compounds. Of interest to chemists and graduate students who want to make themselves acquainted with nuclear magnetic resonance spectroscopy

Magnetic Particle / Magnetic Resonance Imaging: In-Vitro MPI-Guided Real Time Catheter Tracking and 4D Angioplasty Using a Road Map and Blood Pool Tracer Approach.

Science.gov (United States)

Salamon, Johannes; Hofmann, Martin; Jung, Caroline; Kaul, Michael Gerhard; Werner, Franziska; Them, Kolja; Reimer, Rudolph; Nielsen, Peter; Vom Scheidt, Annika; Adam, Gerhard; Knopp, Tobias; Ittrich, Harald

2016-01-01

In-vitro evaluation of the feasibility of 4D real time tracking of endovascular devices and stenosis treatment with a magnetic particle imaging (MPI) / magnetic resonance imaging (MRI) road map approach and an MPI-guided approach using a blood pool tracer. A guide wire and angioplasty-catheter were labeled with a thin layer of magnetic lacquer. For real time MPI a custom made software framework was developed. A stenotic vessel phantom filled with saline or superparamagnetic iron oxide nanoparticles (MM4) was equipped with bimodal fiducial markers for co-registration in preclinical 7T MRI and MPI. In-vitro angioplasty was performed inflating the balloon with saline or MM4. MPI data were acquired using a field of view of 37.3×37.3×18.6 mm3 and a frame rate of 46 volumes/sec. Analysis of the magnetic lacquer-marks on the devices were performed with electron microscopy, atomic absorption spectrometry and micro-computed tomography. Magnetic marks allowed for MPI/MRI guidance of interventional devices. Bimodal fiducial markers enable MPI/MRI image fusion for MRI based roadmapping. MRI roadmapping and the blood pool tracer approach facilitate MPI real time monitoring of in-vitro angioplasty. Successful angioplasty was verified with MPI and MRI. Magnetic marks consist of micrometer sized ferromagnetic plates mainly composed of iron and iron oxide. 4D real time MP imaging, tracking and guiding of endovascular instruments and in-vitro angioplasty is feasible. In addition to an approach that requires a blood pool tracer, MRI based roadmapping might emerge as a promising tool for radiation free 4D MPI-guided interventions.

Magnetic Particle / Magnetic Resonance Imaging: In-Vitro MPI-Guided Real Time Catheter Tracking and 4D Angioplasty Using a Road Map and Blood Pool Tracer Approach.

Directory of Open Access Journals (Sweden)

Johannes Salamon

Full Text Available In-vitro evaluation of the feasibility of 4D real time tracking of endovascular devices and stenosis treatment with a magnetic particle imaging (MPI / magnetic resonance imaging (MRI road map approach and an MPI-guided approach using a blood pool tracer.A guide wire and angioplasty-catheter were labeled with a thin layer of magnetic lacquer. For real time MPI a custom made software framework was developed. A stenotic vessel phantom filled with saline or superparamagnetic iron oxide nanoparticles (MM4 was equipped with bimodal fiducial markers for co-registration in preclinical 7T MRI and MPI. In-vitro angioplasty was performed inflating the balloon with saline or MM4. MPI data were acquired using a field of view of 37.3×37.3×18.6 mm3 and a frame rate of 46 volumes/sec. Analysis of the magnetic lacquer-marks on the devices were performed with electron microscopy, atomic absorption spectrometry and micro-computed tomography.Magnetic marks allowed for MPI/MRI guidance of interventional devices. Bimodal fiducial markers enable MPI/MRI image fusion for MRI based roadmapping. MRI roadmapping and the blood pool tracer approach facilitate MPI real time monitoring of in-vitro angioplasty. Successful angioplasty was verified with MPI and MRI. Magnetic marks consist of micrometer sized ferromagnetic plates mainly composed of iron and iron oxide.4D real time MP imaging, tracking and guiding of endovascular instruments and in-vitro angioplasty is feasible. In addition to an approach that requires a blood pool tracer, MRI based roadmapping might emerge as a promising tool for radiation free 4D MPI-guided interventions.

A practical approach to magnetic resonance imaging of normal and injured tendons: pictorial essay

International Nuclear Information System (INIS)

Forster, B.B.; Khan, K.M.

2003-01-01

The imaging of tendon injury can be troublesome from a number of perspectives. First, tendon injuries are extremely common, accounting for 30%-50% of all sports injuries, and are, therefore, seen frequently at imaging centers. Second, tendons have a unique histology and ultra-structure with a number of normal variations that can mimic pathologic conditions, of which the radiologist should be aware. Finally, although full-thickness tears are easily diagnosed both clinically and with imaging, imaging findings for partial tears overlap those of tendinosis and those of normal tendons, and this can be very troublesome for radiologists, clinicians and patients alike. The objective of this article is to develop a practical approach to the magnetic resonance imaging (MRI) and analysis of tendons, both normal and pathologic, emphasizing the common features at different anatomic locations. (author)

A practical approach to magnetic resonance imaging of normal and injured tendons: pictorial essay

Energy Technology Data Exchange (ETDEWEB)

Forster, B.B. [UBC Hospital, Dept. of Radiology, Vancouver, British Columbia (Canada); Khan, K.M. [Univ. of British Columbia, Dept. of Family Practice, Vancouver, British Columbia (Canada)

2003-10-01

The imaging of tendon injury can be troublesome from a number of perspectives. First, tendon injuries are extremely common, accounting for 30%-50% of all sports injuries, and are, therefore, seen frequently at imaging centers. Second, tendons have a unique histology and ultra-structure with a number of normal variations that can mimic pathologic conditions, of which the radiologist should be aware. Finally, although full-thickness tears are easily diagnosed both clinically and with imaging, imaging findings for partial tears overlap those of tendinosis and those of normal tendons, and this can be very troublesome for radiologists, clinicians and patients alike. The objective of this article is to develop a practical approach to the magnetic resonance imaging (MRI) and analysis of tendons, both normal and pathologic, emphasizing the common features at different anatomic locations. (author)

Complications after liver transplantation: evaluation with magnetic resonance imaging, magnetic resonance cholangiography, and 3-dimensional contrast-enhanced magnetic resonance angiography in a single session

International Nuclear Information System (INIS)

Boraschi, P.; Donati, F.; Gigoni, R.; Salemi, S.; Urbani, L.; Filipponi, F.; Falaschi, F.; Bartolozzi, C.

2008-01-01

To evaluate a comprehensive magnetic resonance imaging (MRI) protocol as noninvasive diagnostic modality for simultaneous detection of parenchymal, biliary, and vascular complications after liver transplantation. Fifty-two liver transplant recipients suspected to have parenchymal, biliary, and (or) vascular complications underwent our MRI protocol at 1.5T unit using a phased array coil. After preliminary acquisition of axial T 1 w and T 2 w sequences, magnetic resonance cholangiography (MRC) was performed through a breath-hold, thin- and thick-slab, single-shot T 2 w sequence in the coronal plane. Contrast-enhanced magnetic resonance angiography (CEMRA) was obtained using a 3-dimensional coronal spoiled gradient-echo sequence, which enabled acquisition of 32 partitions 2.0 mm thick. A fixed dose of 20 ml gadobenate dimeglumine was administered at 2 mL/s. A post-contrast T 1 w sequence was also performed. Two observers in conference reviewed source images and 3-dimensional reconstructions to determine the presence of parenchymal, biliary, and vascular complications. MRI findings were correlated with surgery, endoscopic retrograde cholangiography (ERC), biopsy, digital subtraction angiography (DSA), and imaging follow-up. MRI revealed abnormal findings in 32 out of 52 patients (61%), including biliary complications (anastomotic and nonanastomotic strictures, and lithiasis) in 31, vascular disease (hepatic artery stenosis and thrombosis) in 9, and evidence of hepatic abscess and hematoma in 2. ERC confirmed findings of MRC in 30 cases, but suggested disease underestimation in 2. DSA confirmed 7 magnetic resonance angiogram (MRA) findings, but suggested disease overestimation in 2. MRI combined with MRC and CEMRA can provide a comprehensive assessment of parenchymal, biliary, and vascular complications in most recipients of liver transplantation. (author)

Magnetic resonance imaging - first human images in Australia

International Nuclear Information System (INIS)

Baddeley, H.; Doddrell, D.M.; Brooks, W.M.; Field, J.; Irving, M.; Williams, J.E.

1986-01-01

The use of magnetic resonance imaging, in the demonstration of internal human anatomy and in the diagnosis of disease, has the major advantages that the technique is non-invasive, does not require the use of ionizing radiation and that it can demonstrate neurological and cardiovascular lesions that cannot be diagnosed easily by other imaging methods. The first magnetic resonance images of humans were obtained in Australia in October 1985 on the research instrument of the Queensland Medical Magnetic Resonance Research Centre, which is based at the Mater Hospital in Brisbane

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

Giant magnetic modulation of a planar, hybrid metamolecule resonance

International Nuclear Information System (INIS)

Gregory, Simon A; Stenning, Gavin B G; Bowden, Graham J; De Groot, Peter A J; Zheludev, Nikolay I

2014-01-01

Coupling magnetic elements to metamaterial structures creates hybrid metamolecules with new opportunities. Here we report on the magnetic control of a metamolecule resonance, by utilizing the interaction between a single split ring resonator (SRR) and a magnetic thin film of permalloy. To suppress eddy current shielding, the permalloy films are patterned into arrays of 30–500 μm diameter discs. Strong hybridized resonances were observed at the anticrossing between the split ring resonance and the ferromagnetic resonance (FMR) of the permalloy. In particular, it is possible to achieve 40 dB modulation of the electric (symmetric) mode of the SRR on sweeping the applied magnetic field through the SRR/FMR anticrossing. The results open the way to the design of planar metamaterials, with potential applications in nonlinear metamaterials, tunable metamaterials and spintronics. (papers)

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.)

Magnetic resonance of rubidium atoms passing through a multi-layered transmission magnetic grating

International Nuclear Information System (INIS)

Nagata, Y; Kurokawa, S; Hatakeyama, A

2017-01-01

We measured the magnetic resonance of rubidium atoms passing through periodic magnetic fields generated by two types of multi-layered transmission magnetic grating. One of the gratings reported here was assembled by stacking four layers of magnetic films so that the direction of magnetization alternated at each level. The other grating was assembled so that the magnetization at each level was aligned. For both types of grating, the experimental results were in good agreement with our calculations. We studied the feasibility of extending the frequency band of the grating and narrowing its resonance linewidth by performing calculations. For magnetic resonance precision spectroscopy, we conclude that the multi-layered transmission magnetic grating can generate periodic fields with narrower linewidths at higher frequencies when a larger number of layers are assembled at a shorter period length. Moreover, the frequency band of this type of grating can potentially achieve frequencies of up to hundreds of PHz. (paper)

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.

Improved magnetic resonance fingerprinting reconstruction with low-rank and subspace modeling.

Science.gov (United States)

Zhao, Bo; Setsompop, Kawin; Adalsteinsson, Elfar; Gagoski, Borjan; Ye, Huihui; Ma, Dan; Jiang, Yun; Ellen Grant, P; Griswold, Mark A; Wald, Lawrence L

2018-02-01

This article introduces a constrained imaging method based on low-rank and subspace modeling to improve the accuracy and speed of MR fingerprinting (MRF). A new model-based imaging method is developed for MRF to reconstruct high-quality time-series images and accurate tissue parameter maps (e.g., T 1 , T 2 , and spin density maps). Specifically, the proposed method exploits low-rank approximations of MRF time-series images, and further enforces temporal subspace constraints to capture magnetization dynamics. This allows the time-series image reconstruction problem to be formulated as a simple linear least-squares problem, which enables efficient computation. After image reconstruction, tissue parameter maps are estimated via dictionary-based pattern matching, as in the conventional approach. The effectiveness of the proposed method was evaluated with in vivo experiments. Compared with the conventional MRF reconstruction, the proposed method reconstructs time-series images with significantly reduced aliasing artifacts and noise contamination. Although the conventional approach exhibits some robustness to these corruptions, the improved time-series image reconstruction in turn provides more accurate tissue parameter maps. The improvement is pronounced especially when the acquisition time becomes short. The proposed method significantly improves the accuracy of MRF, and also reduces data acquisition time. Magn Reson Med 79:933-942, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

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 ...

Magnetic nanoparticle imaging using multiple electron paramagnetic resonance activation sequences

International Nuclear Information System (INIS)

Coene, A.; Dupré, L.; Crevecoeur, G.

2015-01-01

Magnetic nanoparticles play an important role in several biomedical applications such as hyperthermia, drug targeting, and disease detection. To realize an effective working of these applications, the spatial distribution of the particles needs to be accurately known, in a non-invasive way. Electron Paramagnetic Resonance (EPR) is a promising and sensitive measurement technique for recovering these distributions. In the conventional approach, EPR is applied with a homogeneous magnetic field. In this paper, we employ different heterogeneous magnetic fields that allow to stabilize the solution of the associated inverse problem and to obtain localized spatial information. A comparison is made between the two approaches and our novel adaptation shows an average increase in reconstruction quality by 5% and is 12 times more robust towards noise. Furthermore, our approach allows to speed up the EPR measurements while still obtaining reconstructions with an improved accuracy and noise robustness compared to homogeneous EPR

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

Deep-level defects in semiconductors: studies by magnetic resonance

International Nuclear Information System (INIS)

Ammerlaan, C.A.J.

1983-01-01

This work is divided into two parts. In the first one, the following topics are discussed: paramagnetic centers in semiconductors, principles of magnetic resonance, spin-Hamiltonian, g-tensor, hyperfine interaction, magnetic resonance spectrometer. In the second part it is dicussed defects studied by magnetic resonance including vacancy and divacancy in silicon, iron in silicon, nitrogen in diamond and antisite defects in III-V compounds. (A.C.A.S.) [pt

An introduction to magnetic resonance in medicine. 2. rev. ed.

International Nuclear Information System (INIS)

Rinck, P.A.; Muller, R.N.; Petersen, S.B.

1990-01-01

The second edition of this introduction to magnetic resonance in medicine is published five years after the first. During these years, magnetic resonance has established itself as a leading diagnostic modality in medicine. With the introduction of fast imaging methods and contrast agents, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) have become even more complicated and complex than before. The purpose of this introduction to biomedical MRI and MRS is to give the readers a basic knowledge that will make it possible for them to pursue studies of their own and to cope with some of the most common problems such as image artifacts or patient questions concerning possible hazards of magnetic resonance. (orig./MG) With 99 figs., 11 tabs

Controlling interactions between highly magnetic atoms with Feshbach resonances.

Science.gov (United States)

Kotochigova, Svetlana

2014-09-01

This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

Resonant Magnetization Tunneling in Molecular Magnets: Where is the Inhomogeneous Broadening?

Science.gov (United States)

Friedman, Jonathan R.; Sarachik, M. P.

1998-03-01

Since the discovery(J. R. Friedman, et al., Phys. Rev. Lett. 76), 3830 (1996) of resonant magnetization tunneling in the molecular magnet Mn_12 there has been intense research into the underlying mechanism of tunneling. Most current theories( V. Dobrovitski and A. Zvezdin, Europhys. Lett. 38), 377 (1997); L. Gunther, Europhys. Lett. 39, 1 (1997); D Garanin and E. Chudnovsky, Phys. Rev. B 56, 11102 (1997). suggest that a local internal (hyperfine or dipole) field transverse to the easy magnetization axis induces tunneling. These theories predict a resonance width orders of magnitude smaller than that actually observed. This discrepancy is attributed to inhomogeneous broadening of the resonance by the random internal fields. We present a detailed study of the tunnel resonance lineshape and show that it is Lorentzian, suggesting it has a deeper physical origin. Since the hyperfine fields are believed to be comparable to the observed width, it is surprising that there is no Gaussian broadening.

Capsular contracture and possible implant rupture: is magnetic resonance imaging useful?

Science.gov (United States)

Paetau, Alyssa A; McLaughlin, Sarah A; McNeil, Rebecca B; Sternberg, Erez; TerKonda, Sarvam P; Waldorf, James C; Perdikis, Galen

2010-03-01

Currently, magnetic resonance imaging is considered the accepted standard to evaluate breast implant integrity. To evaluate its utility in diagnosing ruptured silicone implants in the setting of capsular contracture and to correlate the preoperative assessment of implant integrity with or without magnetic resonance imaging with operative findings, 319 capsulectomies (171 patients with capsular contractures) were retrospectively reviewed. Preoperative magnetic resonance imaging was done on 160 implants, whereas the remaining 159 were evaluated using only physical examination and/or mammography. Postoperative results were analyzed to determine the sensitivity, specificity, and accuracy of preoperative magnetic resonance imaging in comparison with clinical and/or mammography evaluation alone. Although occasionally valuable, overall, preoperative magnetic resonance imaging was no more accurate than clinical evaluation with or without mammography in predicting implant status: magnetic resonance imaging 124 of 160 (78 percent) and clinical 121 of 159 (76 percent; p = 0.77). In the setting of capsular contracture, physical examination with or without mammogram is as accurate as magnetic resonance imaging in determining implant integrity. Although magnetic resonance imaging is a sensitive diagnostic tool, in symptomatic patients with capsular contracture, it cannot be viewed as infallible.

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

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

On the Fer expansion: Applications in solid-state nuclear magnetic resonance and physics

Energy Technology Data Exchange (ETDEWEB)

Mananga, Eugene Stephane, E-mail: esm041@mail.harvard.edu

2016-01-18

Theoretical approaches are useful and powerful tools for more accurate and efficient spin dynamics simulation to understand experiments and devising new RF pulse sequence in nuclear magnetic resonance. Solid-state NMR is definitely a timely topic or area of research, and not many papers on the respective theories are available in the literature of nuclear magnetic resonance or physics reports. This report presents the power and the salient features of the promising theoretical approach called Fer expansion that is helpful to describe the evolution of the spin system in nuclear magnetic resonance. The report presents a broad view of algorithms of spin dynamics based on the Fer expansion which provides procedures to control and describe the spin dynamics in solid-state NMR. Significant applications of the Fer expansion are illustrated in NMR and in physics such as classical physics, nonlinear dynamics systems, celestial mechanics and dynamical astronomy, hydrodynamics, nuclear, atomic, molecular physics, and quantum mechanics, quantum field theory, high energy physics, electromagnetism. The aim of this report is to bring to the attention of the spin dynamics community, the bridge that exists between solid-state NMR and other related fields of physics and applied mathematics.

On the Fer expansion: Applications in solid-state nuclear magnetic resonance and physics

International Nuclear Information System (INIS)

Mananga, Eugene Stephane

2016-01-01

Theoretical approaches are useful and powerful tools for more accurate and efficient spin dynamics simulation to understand experiments and devising new RF pulse sequence in nuclear magnetic resonance. Solid-state NMR is definitely a timely topic or area of research, and not many papers on the respective theories are available in the literature of nuclear magnetic resonance or physics reports. This report presents the power and the salient features of the promising theoretical approach called Fer expansion that is helpful to describe the evolution of the spin system in nuclear magnetic resonance. The report presents a broad view of algorithms of spin dynamics based on the Fer expansion which provides procedures to control and describe the spin dynamics in solid-state NMR. Significant applications of the Fer expansion are illustrated in NMR and in physics such as classical physics, nonlinear dynamics systems, celestial mechanics and dynamical astronomy, hydrodynamics, nuclear, atomic, molecular physics, and quantum mechanics, quantum field theory, high energy physics, electromagnetism. The aim of this report is to bring to the attention of the spin dynamics community, the bridge that exists between solid-state NMR and other related fields of physics and applied mathematics.

Magnetic resonance force microscopy quantum computer with tellurium donors in silicon.

Science.gov (United States)

Berman, G P; Doolen, G D; Hammel, P C; Tsifrinovich, V I

2001-03-26

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines well-developed silicon technology and expected advances in MRFM. Our proposal does not use electrostatic gates to realize quantum logic operations.

Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

International Nuclear Information System (INIS)

Berman, G. P.; Doolen, G. D.; Hammel, P. C.; Tsifrinovich, V. I.

2001-01-01

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines well-developed silicon technology and expected advances in MRFM. Our proposal does not use electrostatic gates to realize quantum logic operations

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...

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.

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.

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)

21 CFR 892.1000 - Magnetic resonance diagnostic device.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Magnetic resonance diagnostic device. 892.1000 Section 892.1000 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1000 Magnetic resonance diagnostic...

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

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

Resonance magnetic x-ray scattering study of erbium

DEFF Research Database (Denmark)

Sanyal, M.K.; Gibbs, D.; Bohr, J.

1994-01-01

The magnetic phases of erbium have been studied by resonance x-ray-scattering techniques. When the incident x-ray energy is tuned near the L(III) absorption edge, large resonant enhancements of the magnetic scattering are observed above 18 K. We have measured the energy and polarization dependence...... of this magnetic scattering and analyzed it using a simple model based on electric dipole and quadrupole transitions among atomic orbitals. The line shapes can be fitted to a magnetic structure combining both c-axis-modulated and basal-plane components. Below 18 K, we have observed unusual behavior of the magnetic...

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) ...

Science Drivers and Technical Challenges for Advanced Magnetic Resonance

Energy Technology Data Exchange (ETDEWEB)

Mueller, Karl T.; Pruski, Marek; Washton, Nancy M.; Lipton, Andrew S.

2013-03-07

This report recaps the "Science Drivers and Technical Challenges for Advanced Magnetic Resonance" workshop, held in late 2011. This exploratory workshop's goal was to discuss and address challenges for the next generation of magnetic resonance experimentation. During the workshop, participants from throughout the world outlined the science drivers and instrumentation demands for high-field dynamic nuclear polarization (DNP) and associated magnetic resonance techniques, discussed barriers to their advancement, and deliberated the path forward for significant and impactful advances in the field.

Tissue discrimination in magnetic resonance imaging of the rotator cuff

International Nuclear Information System (INIS)

Meschino, G J; Comas, D S; González, M A; Ballarin, V L; Capiel, C

2016-01-01

Evaluation and diagnosis of diseases of the muscles within the rotator cuff can be done using different modalities, being the Magnetic Resonance the method more widely used. There are criteria to evaluate the degree of fat infiltration and muscle atrophy, but these have low accuracy and show great variability inter and intra observer. In this paper, an analysis of the texture features of the rotator cuff muscles is performed to classify them and other tissues. A general supervised classification approach was used, combining forward-search as feature selection method with kNN as classification rule. Sections of Magnetic Resonance Images of the tissues of interest were selected by specialist doctors and they were considered as Gold Standard. Accuracies obtained were of 93% for T1-weighted images and 92% for T2-weighted images. As an immediate future work, the combination of both sequences of images will be considered, expecting to improve the results, as well as the use of other sequences of Magnetic Resonance Images. This work represents an initial point for the classification and quantification of fat infiltration and muscle atrophy degree. From this initial point, it is expected to make an accurate and objective system which will result in benefits for future research and for patients’ health. (paper)

Tissue discrimination in magnetic resonance imaging of the rotator cuff

Science.gov (United States)

Meschino, G. J.; Comas, D. S.; González, M. A.; Capiel, C.; Ballarin, V. L.

2016-04-01

Evaluation and diagnosis of diseases of the muscles within the rotator cuff can be done using different modalities, being the Magnetic Resonance the method more widely used. There are criteria to evaluate the degree of fat infiltration and muscle atrophy, but these have low accuracy and show great variability inter and intra observer. In this paper, an analysis of the texture features of the rotator cuff muscles is performed to classify them and other tissues. A general supervised classification approach was used, combining forward-search as feature selection method with kNN as classification rule. Sections of Magnetic Resonance Images of the tissues of interest were selected by specialist doctors and they were considered as Gold Standard. Accuracies obtained were of 93% for T1-weighted images and 92% for T2-weighted images. As an immediate future work, the combination of both sequences of images will be considered, expecting to improve the results, as well as the use of other sequences of Magnetic Resonance Images. This work represents an initial point for the classification and quantification of fat infiltration and muscle atrophy degree. From this initial point, it is expected to make an accurate and objective system which will result in benefits for future research and for patients’ health.

Metamaterial Combining Electric- and Magnetic-Dipole-Based Configurations for Unique Dual-Band Signal Enhancement in Ultrahigh-Field Magnetic Resonance Imaging.

Science.gov (United States)

Schmidt, Rita; Webb, Andrew

2017-10-11

Magnetic resonance imaging and spectroscopy (MRI and MRS) are both widely used techniques in medical diagnostics and research. One of the major thrusts in recent years has been the introduction of ultrahigh-field magnets in order to boost the sensitivity. Several MRI studies have examined further potential improvements in sensitivity using metamaterials, focusing on single frequency applications. However, metamaterials have yet to reach a level that is practical for routine MRI use. In this work, we explore a new metamaterial implementation for MRI, a dual-nuclei resonant structure, which can be used for both proton and heteronuclear magnetic resonance. Our approach combines two configurations, one based on a set of electric dipoles for the low frequency band, and the second based on a set of magnetic dipoles for the high frequency band. We focus on the implementation of a dual-nuclei metamaterial for phosphorus and proton imaging and spectroscopy at an ultrahigh-field strength of 7 T. In vivo scans using this flexible and compact structure show that it locally enhances both the phosphorus and proton transmit and receive sensitivities.

Resonant cell of a double nuclear electron resonance spectrometer for performance in a 120-350 Gs magnetic field

International Nuclear Information System (INIS)

Baldin, V.I.; Stepanov, A.P.

1976-01-01

Spectrometer double-frequency resonance cell construction of a double nuclear electron resonance for operation in 120-350 Gs magnetic fields is described. The cell has been developed from a special decimeter resonator with a concentrated capacitance. The electric and magnetic components of a high frequency field are efficiently divided in the separator. Therefore, the insertion of a measuring coil and a sample in the maximum of the magnetic component of the field does not practically affect the distribution and parameters of the high-frequency field. The double-frequency resonance cell proposed provides for a higher accuracy of measuring amplifications of the nuclear magnetic resonance signals when there is the overhauzer effect for 120-350 Gs magnetic fields

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....

Assessment of structural lesions in sacroiliac joints enhances diagnostic utility of magnetic resonance imaging in early spondylarthritis

DEFF Research Database (Denmark)

Weber, Ulrich; Lambert, Robert G W; Pedersen, Susanne J

2010-01-01

To compare the diagnostic utility of T1-weighted and STIR magnetic resonance imaging (MRI) sequences in early spondylarthritis (SpA) using a standardized approach to the evaluation of sacroiliac (SI) joints, and to test whether systematic calibration of readers directed at recognition of abnormal......To compare the diagnostic utility of T1-weighted and STIR magnetic resonance imaging (MRI) sequences in early spondylarthritis (SpA) using a standardized approach to the evaluation of sacroiliac (SI) joints, and to test whether systematic calibration of readers directed at recognition...

Effect of resonance line shape on precision measurements of nuclear magnetic resonance shifts

International Nuclear Information System (INIS)

Kachurin, A.M.; Smelyanskij, A.Ya.

1986-01-01

Effect of resonance line shape on the systematic error of precision measurements of nuclear magnetic resonance (NMR) shifts of high resolution (on the center of NMR dispersion line) is analysed. Effect of the device resonance line form-function asymmetry is evaluated; the form-function is determined by configuration of the spectrometer magnetic field and enters the convolution, which describes the resonance line form. It is shown that with the increase of the relaxation line width the form-function effect on the measurement error yields to zero. The form-function effect on measurements and correction of a phase angle of NMR detection is evaluated. The method of semiquantitative evaluation of resonance line and NMR spectrometer parameters, guaranteeing the systematic error of the given infinitesimal, is presented

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

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

Molecular structure and motion in zero field magnetic resonance

International Nuclear Information System (INIS)

Jarvie, T.P.

1989-10-01

Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed

Diagnostic imaging of psoriatic arthritis. Part II: magnetic resonance imaging and ultrasonography

Directory of Open Access Journals (Sweden)

Iwona Sudoł-Szopińska

2016-06-01

Full Text Available Plain radiography reveals specific, yet late changes of advanced psoriatic arthritis. Early inflammatory changes are seen both on magnetic resonance imaging and ultrasound within peripheral joints (arthritis, synovitis, tendons sheaths (tenosynovitis, tendovaginitis and entheses (enthesitis, enthesopathy. In addition, magnetic resonance imaging enables the assessment of inflammatory features in the sacroiliac joints (sacroiliitis, and the spine (spondylitis. In this article, we review current opinions on the diagnostics of some selective, and distinctive features of psoriatic arthritis concerning magnetic resonance imaging and ultrasound and present some hypotheses on psoriatic arthritis etiopathogenesis, which have been studied with the use of magnetic resonance imaging. The following elements of the psoriatic arthritis are discussed: enthesitis, extracapsular inflammation, dactylitis, distal interphalangeal joint and nail disease, and the ability of magnetic resonance imaging to differentiate undifferentiated arthritis, the value of whole-body magnetic resonance imaging and dynamic contrast-enhanced magnetic resonance imaging.

Magnetic resonance spectroscopy as a diagnostic modality for carcinoma thyroid

International Nuclear Information System (INIS)

Gupta, Nikhil; Kakar, Arun K.; Chowdhury, Veena; Gulati, Praveen; Shankar, L. Ravi; Vindal, Anubhav

2007-01-01

Aim: The aim of this study was to observe the findings of magnetic resonance spectroscopy of solitary thyroid nodules and its correlation with histopathology. Materials and methods: In this study, magnetic resonance spectroscopy was carried out on 26 patients having solitary thyroid nodules. Magnetic resonance spectroscopy (MRS) was performed on a 1.5 T super conductive system with gradient strength of 33 mTs. Fine needle aspiration cytology was done after MRS. All 26 patients underwent surgery either because of cytopathologically proven malignancy or because of cosmetic reasons. Findings of magnetic resonance spectroscopy were compared with histopathology of thyroid specimens. Results and conclusion: It was seen that presence or absence of choline peak correlates very well with presence or absence of malignant foci with in the nodule (sensitivity = 100%; specificity = 88.88%). These results indicate that magnetic resonance spectroscopy may prove to be an useful diagnostic modality for carcinoma thyroid

Numerical studies of radiofrequency of the electromagnetic radiation power absorption in paediatrics undergoing brain magnetic resonance imaging

Directory of Open Access Journals (Sweden)

C. Subaar

2017-07-01

Full Text Available Magnetic resonance imaging current operating frequencies are above 100 kHz which is converted to heat through resistive tissue losses during imaging. The imaging is coupled with a concurring increase in temperature in patients. Magnetic resonance imaging of the brain has seen a rising clinical request during diagnosis and therefore become imperative that its safety issues be assessed. This study modelled Pennes' classical bio-heat equation using Finite Difference Method (FDM approach and with the help of MATLAB programming language, predicted three dimensional steady state temperature distributions in patients during magnetic resonance imaging. Sixty-four paediatric patients' referred for (head brain magnetic resonance imaging scan at 37 Military Hospital and the Diagnostic Center Limited, Ghana, pre-scan and post-scan temperatures were measured at the right tympanic. The numerically steady state temperature distribution during magnetic resonance imaging shows that there is excessive temperature elevation at the skin surface of the patients. The resulting skin heating during magnetic resonance imaging can reach dangerous level which suggests that the ohmic heating of tissue is greatest at the surface and minimal at the center of the patient's brain. Though the experimental results show that patients brain temperature increase after imaging, all measured temperatures were within acceptable safe levels.

Deep convolutional neural network and 3D deformable approach for tissue segmentation in musculoskeletal magnetic resonance imaging.

Science.gov (United States)

Liu, Fang; Zhou, Zhaoye; Jang, Hyungseok; Samsonov, Alexey; Zhao, Gengyan; Kijowski, Richard

2018-04-01

To describe and evaluate a new fully automated musculoskeletal tissue segmentation method using deep convolutional neural network (CNN) and three-dimensional (3D) simplex deformable modeling to improve the accuracy and efficiency of cartilage and bone segmentation within the knee joint. A fully automated segmentation pipeline was built by combining a semantic segmentation CNN and 3D simplex deformable modeling. A CNN technique called SegNet was applied as the core of the segmentation method to perform high resolution pixel-wise multi-class tissue classification. The 3D simplex deformable modeling refined the output from SegNet to preserve the overall shape and maintain a desirable smooth surface for musculoskeletal structure. The fully automated segmentation method was tested using a publicly available knee image data set to compare with currently used state-of-the-art segmentation methods. The fully automated method was also evaluated on two different data sets, which include morphological and quantitative MR images with different tissue contrasts. The proposed fully automated segmentation method provided good segmentation performance with segmentation accuracy superior to most of state-of-the-art methods in the publicly available knee image data set. The method also demonstrated versatile segmentation performance on both morphological and quantitative musculoskeletal MR images with different tissue contrasts and spatial resolutions. The study demonstrates that the combined CNN and 3D deformable modeling approach is useful for performing rapid and accurate cartilage and bone segmentation within the knee joint. The CNN has promising potential applications in musculoskeletal imaging. Magn Reson Med 79:2379-2391, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Magnetic resonance, especially spin echo, in spinor Bose-Einstein condensates

International Nuclear Information System (INIS)

Yasunaga, Masashi; Tsubota, Makoto

2009-01-01

Magnetic resonance, especially NMR and ESR, has been studied in magnetic materials for a long time, having been used in various fields. Spin echo is typical phenomenon in magnetic resonance. The magnetic resonance should be applied to spinor Bose-Einstein condensates (BECs). We numerically study spin echo of a spinor BEC in a gradient magnetic field by calculating the spin-1 two-dimensional Gross-Pitaevskii equations, obtaining the recovery of the signal of the spins, which is called spin echo. We will discuss the relation between the spin echo and the Stern-Gelrach separation in the system.

Quantitative magnetic resonance micro-imaging methods for pharmaceutical research.

Science.gov (United States)

Mantle, M D

2011-09-30

The use of magnetic resonance imaging (MRI) as a tool in pharmaceutical research is now well established and the current literature covers a multitude of different pharmaceutically relevant research areas. This review focuses on the use of quantitative magnetic resonance micro-imaging techniques and how they have been exploited to extract information that is of direct relevance to the pharmaceutical industry. The article is divided into two main areas. The first half outlines the theoretical aspects of magnetic resonance and deals with basic magnetic resonance theory, the effects of nuclear spin-lattice (T(1)), spin-spin (T(2)) relaxation and molecular diffusion upon image quantitation, and discusses the applications of rapid magnetic resonance imaging techniques. In addition to the theory, the review aims to provide some practical guidelines for the pharmaceutical researcher with an interest in MRI as to which MRI pulse sequences/protocols should be used and when. The second half of the article reviews the recent advances and developments that have appeared in the literature concerning the use of quantitative micro-imaging methods to pharmaceutically relevant research. Copyright © 2010 Elsevier B.V. All rights reserved.

Comparative analysis of nuclear magnetic resonance well logging and nuclear magnetic resonance mud logging

International Nuclear Information System (INIS)

Yuan Zugui

2008-01-01

The hydrogen atoms in oil and water are able to resonate and generate signals in the magnetic field, which is used by the NMR (nuclear magnetic resonance) technology in petroleum engineering to research and evaluate rock characteristics. NMR well logging was used to measure the physical property parameters of the strata in well bore, whereas NMR mud logging was used to analyze (while drilling) the physical property parameters of cores, cuttings and sidewall coring samples on surface (drilling site). Based on the comparative analysis of the porosity and permeability parameters obtained by NMR well logging and those from analysis of the cores, cuttings and sidewall coring samples by NMR mud logging in the same depth of 13 wells, these two methods are of certain difference, but their integral tendency is relatively good. (authors)

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

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.

Normal perinatal and paediatric postmortem magnetic resonance imaging appearances

Energy Technology Data Exchange (ETDEWEB)

Arthurs, Owen J. [Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London (United Kingdom); UCL Institute of Child Health, London (United Kingdom); Barber, Joy L. [Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London (United Kingdom); Taylor, Andrew M. [Cardiorespiratory Division, Great Ormond Street Hospital for Children NHS Foundation Trust, London (United Kingdom); UCL Institute of Cardiovascular Science, Centre for Cardiovascular Imaging, London (United Kingdom); Sebire, Neil J. [UCL Institute of Child Health, London (United Kingdom); Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London (United Kingdom)

2015-04-01

As postmortem imaging becomes more widely used following perinatal and paediatric deaths, the correct interpretation of images becomes imperative, particularly given the increased use of postmortem magnetic resonance imaging. Many pathological processes may have similar appearances in life and following death. A thorough knowledge of normal postmortem changes is therefore required within postmortem magnetic resonance imaging to ensure that these are not mistakenly interpreted as significant pathology. Similarly, some changes that are interpreted as pathological if they occur during life may be artefacts on postmortem magnetic resonance imaging that are of limited significance. This review serves to illustrate briefly those postmortem magnetic resonance imaging changes as part of the normal changes after death in fetuses and children, and highlight imaging findings that may confuse or mislead an observer to identifying pathology where none is present. (orig.)

A personal computer-based nuclear magnetic resonance spectrometer

Science.gov (United States)

Job, Constantin; Pearson, Robert M.; Brown, Michael F.

1994-11-01

Nuclear magnetic resonance (NMR) spectroscopy using personal computer-based hardware has the potential of enabling the application of NMR methods to fields where conventional state of the art equipment is either impractical or too costly. With such a strategy for data acquisition and processing, disciplines including civil engineering, agriculture, geology, archaeology, and others have the possibility of utilizing magnetic resonance techniques within the laboratory or conducting applications directly in the field. Another aspect is the possibility of utilizing existing NMR magnets which may be in good condition but unused because of outdated or nonrepairable electronics. Moreover, NMR applications based on personal computer technology may open up teaching possibilities at the college or even secondary school level. The goal of developing such a personal computer (PC)-based NMR standard is facilitated by existing technologies including logic cell arrays, direct digital frequency synthesis, use of PC-based electrical engineering software tools to fabricate electronic circuits, and the use of permanent magnets based on neodymium-iron-boron alloy. Utilizing such an approach, we have been able to place essentially an entire NMR spectrometer console on two printed circuit boards, with the exception of the receiver and radio frequency power amplifier. Future upgrades to include the deuterium lock and the decoupler unit are readily envisioned. The continued development of such PC-based NMR spectrometers is expected to benefit from the fast growing, practical, and low cost personal computer market.

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

'Blocking' effects in magnetic resonance? The ferromagnetic nanowires case

International Nuclear Information System (INIS)

Ramos, C.A.; De Biasi, E.; Zysler, R.D.; Vassallo Brigneti, E.; Vazquez, M.

2007-01-01

We present magnetic resonance results obtained at L, X, and Q bands (1.2, 9.4 and 34GHz, respectively) on ferromagnetic nanowires with a hysteresis cycle characterized by a remanent magnetization M r /M s ∼0.92 and a coercive field H c =1.0kOe. The hysteretic response of the ferromagnetic resonance spectra is discussed in terms of independent contributions of the nanowires aligned along and opposite to the applied field. We will discuss the implications of this study on the magnetic resonance in nanoparticles and other systems with large anisotropy

A Novel Magnetic Resonance Imaging (MRI) Approach for Measuring Weak Electric Currents Inside the Human Brain

DEFF Research Database (Denmark)

Göksu, Cihan

of individual ohmic conductivity values may open up the possibility of creating more realistic and accurate head models, which may ameliorate the simulations and practical use of NIBS techniques. Magnetic resonance current density imaging (MRCDI) and magnetic resonance electrical impedance tomography (MREIT......Knowing the electrical conductivity and current density distribution inside the human brain will be useful in various biomedical applications, i.e. for improving the efficiency of non-invasive brain stimulation (NIBS) techniques, the accuracy of electroencephalography (EEG......) and magnetoencephalography (MEG) source localization, or localization of pathological tissues. For example, the accuracy of electric field simulations for NIBS techniques is currently reduced by assigning inaccurate ohmic conductivity values taken from literature to different brain tissues. Therefore, the knowledge...

Bayesian estimation of multicomponent relaxation parameters in magnetic resonance fingerprinting.

Science.gov (United States)

McGivney, Debra; Deshmane, Anagha; Jiang, Yun; Ma, Dan; Badve, Chaitra; Sloan, Andrew; Gulani, Vikas; Griswold, Mark

2018-07-01

To estimate multiple components within a single voxel in magnetic resonance fingerprinting when the number and types of tissues comprising the voxel are not known a priori. Multiple tissue components within a single voxel are potentially separable with magnetic resonance fingerprinting as a result of differences in signal evolutions of each component. The Bayesian framework for inverse problems provides a natural and flexible setting for solving this problem when the tissue composition per voxel is unknown. Assuming that only a few entries from the dictionary contribute to a mixed signal, sparsity-promoting priors can be placed upon the solution. An iterative algorithm is applied to compute the maximum a posteriori estimator of the posterior probability density to determine the magnetic resonance fingerprinting dictionary entries that contribute most significantly to mixed or pure voxels. Simulation results show that the algorithm is robust in finding the component tissues of mixed voxels. Preliminary in vivo data confirm this result, and show good agreement in voxels containing pure tissue. The Bayesian framework and algorithm shown provide accurate solutions for the partial-volume problem in magnetic resonance fingerprinting. The flexibility of the method will allow further study into different priors and hyperpriors that can be applied in the model. Magn Reson Med 80:159-170, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Low field magnetic resonance experiments in superfluid 3He--A

International Nuclear Information System (INIS)

Gully, W.J. Jr.

1976-01-01

Measurements of the longitudinal and transverse nuclear magnetic resonance signals have been made on the A phase of liquid 3 He. They were performed on a sample of 3 He self-cooled by the Pomeranchuk effect to the critical temperature of the superfluid at 2.7 m 0 K. The longitudinal resonance is a magnetic mode of the liquid excited by radio frequency magnetic fields applied in the direction of the static magnetic field. Frequency profiles of this resonance were indirectly obtained by contour techniques from signals recorded by sweeping the temperature. Its frequency is found to be related to the frequency shift of the transverse resonance in agreement with theoretical predictions for the ABM pairing state. Its linewidth also agrees with theoretical predictions based upon dissipative phenomena peculiar to the superfluid phase. An analysis of the linewidth of the longitudinal resonance yields a value for the quasiparticle collision time. Transverse NMR lines were also studied. In low magnetic fields (20 Oersted) these lines were found to become extremely broad. This is shown to be a manifestation of the same collisional processes that broaden the longitudinal resonance lines. Also, the effects of various textures on the resonance lines are discussed, including the results of an attempt to create a single domain of 3 He with crossed electric and magnetic fields

Measurement of single electron and nuclear spin states based on optically detected magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Berman, Gennady P [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bishop, Alan R [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Chernobrod, Boris M [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hawley, Marilyn E [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Brown, Geoffrey W [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tsifrinovich, Vladimir I [Polytechnic University, Brooklyn, NY 11201 (United States)

2006-05-15

A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution.

Measurement of single electron and nuclear spin states based on optically detected magnetic resonance

International Nuclear Information System (INIS)

Berman, Gennady P; Bishop, Alan R; Chernobrod, Boris M; Hawley, Marilyn E; Brown, Geoffrey W; Tsifrinovich, Vladimir I

2006-01-01

A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution

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

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…

Moessbauer and magnetic resonance experiments on amorphous iron-silicon films

International Nuclear Information System (INIS)

Bansal, C.; Campbell, S.J.; Stewart, A.M.

1982-01-01

Moessbauer measurements at room temperature and 4.2 K, and room temperature magnetic resonance measurments on a series of amorphous Fesub(x)Sisub(1-x) thin films (0.23 <= x <= 0.81) are presented. The concentration dependence of the isomer shifts and quadrupole splittings provides information on the nature of the local coordination in these amorphous materials. Analysis of the distributions of magnetic hyperfine splitting combined with the presence of multiple resonance in the magnetic resonance data indiates that magnetoanisotropy plays a dominant role in determining the magnetic behaviour of these films. (orig.)

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

Maximum Entropy Approach in Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

Science.gov (United States)

Farsani, Zahra Amini; Schmid, Volker J

2017-01-01

In the estimation of physiological kinetic parameters from Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) data, the determination of the arterial input function (AIF) plays a key role. This paper proposes a Bayesian method to estimate the physiological parameters of DCE-MRI along with the AIF in situations, where no measurement of the AIF is available. In the proposed algorithm, the maximum entropy method (MEM) is combined with the maximum a posterior approach (MAP). To this end, MEM is used to specify a prior probability distribution of the unknown AIF. The ability of this method to estimate the AIF is validated using the Kullback-Leibler divergence. Subsequently, the kinetic parameters can be estimated with MAP. The proposed algorithm is evaluated with a data set from a breast cancer MRI study. The application shows that the AIF can reliably be determined from the DCE-MRI data using MEM. Kinetic parameters can be estimated subsequently. The maximum entropy method is a powerful tool to reconstructing images from many types of data. This method is useful for generating the probability distribution based on given information. The proposed method gives an alternative way to assess the input function from the existing data. The proposed method allows a good fit of the data and therefore a better estimation of the kinetic parameters. In the end, this allows for a more reliable use of DCE-MRI. Schattauer GmbH.

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.)

On effect of stability of magnetic resonance position by harmonized field

International Nuclear Information System (INIS)

Ivanchenko, E.A.; Tolstoluzhsky, A.P.

2006-01-01

The formalism of density matrix in a two level system is used to study the time-periodic modulation of the magnetic field stabilizating the magnetic resonance position. An exact solution for density matrix at resonance is found. It is shown that the fundamental resonance is stable with respect to consistent variations of longitudinal and transversal magnetic fields. A differential equation for the transition probability is obtained. The dependence of time-averaged spin flip probability on the normalized Larmor frequency was numerically researched in different parameter regimes with account of dissipation and decoherence. It is shown that the position of the main resonance is independent of field deformation and dissipation; only the width of resonance line changes upon field deformation and dissipation. The odd parametric (multi-photon) resonance transitions is studied. Static magnetization induced by time-periodic modulated magnetic field is considered. The results of the investigation may be useful for analysis of interference experiments, improvement of magnetic spectrometers and in the field of quantum computing manipulation of q-bits

Defining active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI group

DEFF Research Database (Denmark)

Rudwaleit, M; Jurik, A G; Hermann, K-G A

2009-01-01

BACKGROUND: Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. OBJECTIVES: To identify and describe MRI findings in sacroiliitis and...... relevant for sacroiliitis have been defined by consensus by a group of rheumatologists and radiologists. These definitions should help in applying correctly the imaging feature "active sacroiliitis by MRI" in the new ASAS classification criteria for axial SpA.......BACKGROUND: Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. OBJECTIVES: To identify and describe MRI findings in sacroiliitis...... conditions which may mimic SpA. Descriptions of the pathological findings and technical requirements for the appropriate acquisition were formulated. In a consensual approach MRI findings considered to be essential for sacroiliitis were defined. RESULTS: Active inflammatory lesions such as bone marrow oedema...

Magnetic hysteresis effects in superconducting coplanar microwave resonators

Energy Technology Data Exchange (ETDEWEB)

Bothner, D.; Gaber, T.; Kemmler, M.; Gruenzweig, M.; Ferdinand, B.; Koelle, D.; Kleiner, R. [Universitaet Tuebingen (Germany); Wuensch, S.; Siegel, M. [Karlsruher Institut fuer Technologie (Germany); Mikheenko, P.; Johansen, T.H. [University of Oslo (Norway)

2013-07-01

We present experimental data regarding the impact of external magnetic fields on quality factor and resonance frequency of superconducting microwave resonators in a coplanar waveguide geometry. In particular we focus on the influence of magnetic history and show with the assistance of numerical calculations that the found hysteretic behaviour can be well understood with a highly inhomogeneous microwave current density in combination with established field penetration models for type-II superconducting thin films. Furthermore we have used magneto-optical imaging techniques to check the field distribution which we have assumed in our calculations. Finally, we demonstrate that and how the observed hysteretic behaviour can be used to optimize and tune the resonator performance for possible hybrid quantum sytems in magnetic fields.

Metal complex-based templates and nanostructures for magnetic resonance/optical multimodal imaging agents

NARCIS (Netherlands)

Galindo Millan, Jealemy

2012-01-01

In this thesis, new approaches directed towards simple and functional imaging agents (IAs) for magnetic resonance (MR) and fluorescence multimodal imaging are proposed. In Chapter 3, hybrid silver nanostructures (hAgNSs), grown using a polyamino carboxylic acid scaffold, namely

Unraveling multi-spin effects in rotational resonance nuclear magnetic resonance using effective reduced density matrix theory

International Nuclear Information System (INIS)

SivaRanjan, Uppala; Ramachandran, Ramesh

2014-01-01

A quantum-mechanical model integrating the concepts of reduced density matrix and effective Hamiltonians is proposed to explain the multi-spin effects observed in rotational resonance (R 2 ) nuclear magnetic resonance (NMR) experiments. Employing this approach, the spin system of interest is described in a reduced subspace inclusive of its coupling to the surroundings. Through suitable model systems, the utility of our theory is demonstrated and verified with simulations emerging from both analytic and numerical methods. The analytic results presented in this article provide an accurate description/interpretation of R 2 experimental results and could serve as a test-bed for distinguishing coherent/incoherent effects in solid-state NMR

Unraveling multi-spin effects in rotational resonance nuclear magnetic resonance using effective reduced density matrix theory

Energy Technology Data Exchange (ETDEWEB)

SivaRanjan, Uppala; Ramachandran, Ramesh, E-mail: rramesh@iisermohali.ac.in [Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Manauli, P.O. Box-140306, Mohali, Punjab (India)

2014-02-07

A quantum-mechanical model integrating the concepts of reduced density matrix and effective Hamiltonians is proposed to explain the multi-spin effects observed in rotational resonance (R{sup 2}) nuclear magnetic resonance (NMR) experiments. Employing this approach, the spin system of interest is described in a reduced subspace inclusive of its coupling to the surroundings. Through suitable model systems, the utility of our theory is demonstrated and verified with simulations emerging from both analytic and numerical methods. The analytic results presented in this article provide an accurate description/interpretation of R{sup 2} experimental results and could serve as a test-bed for distinguishing coherent/incoherent effects in solid-state NMR.

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)

Evaluation of magnetic resonance velocimetry for steady flow.

Science.gov (United States)

Ku, D N; Biancheri, C L; Pettigrew, R I; Peifer, J W; Markou, C P; Engels, H

1990-11-01

Whole body magnetic resonance (MR) imaging has recently become an important diagnostic tool for cardiovascular diseases. The technique of magnetic resonance phase velocity encoding allows the quantitative measurement of velocity for an arbitrary component direction. A study was initiated to determine the ability and accuracy of MR velocimetry to measure a wide range of flow conditions including flow separation, three-dimensional secondary flow, high velocity gradients, and turbulence. A steady flow system pumped water doped with manganese chloride through a variety of test sections. Images were produced using gradient echo sequences on test sections including a straight tube, a curved tube, a smoothly converging-diverging nozzle, and an orifice. Magnetic resonance measurements of laminar and turbulent flows were depicted as cross-sectional velocity profiles. MR velocity measurements revealed such flow behavior as spatially varying velocity, recirculation and secondary flows over a wide range of conditions. Comparisons made with published experimental laser Doppler anemometry measurements and theoretical calculations for similar flow conditions revealed excellent accuracy and precision levels. The successful measurement of velocity profiles for a variety of flow conditions and geometries indicate that magnetic resonance imaging is an accurate, non-contacting velocimeter.

Introduction to magnetic resonance and its application to dipole magnet testing

International Nuclear Information System (INIS)

Clark, W.G.

1992-01-01

An introduction to the features of magnetic resonance that are essential for understanding its application to testing accelerator dipole magnets is presented, including the accuracy that can be expected in field measurements and the factors that limit it. The use of an array of coils to measure the multipole moments of dipole magnets is discussed

Direct imaging of neural currents using ultra-low field magnetic resonance techniques

Science.gov (United States)

Volegov, Petr L [Los Alamos, NM; Matlashov, Andrei N [Los Alamos, NM; Mosher, John C [Los Alamos, NM; Espy, Michelle A [Los Alamos, NM; Kraus, Jr., Robert H.

2009-08-11

Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

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) - ...

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, ...

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

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.

Magnetic moment oscillation in ammonium perchlorate in a DC SQUID-based magnetic resonance experiment

International Nuclear Information System (INIS)

Montero, V.; Cernicchiaro, G.

2008-01-01

In this work we describe experimental results in which a DC SQUID (superconducting quantum interference device) is used as free induction decay detector. Measurements of a solid ammonium perchlorate (NH 4 ClO 4 ) sample were performed, in zero field, at 4.2 K. Unexpected magnetic moment oscillations were detected at 1.5 kHz. The computation of the magnetic fields suggests that the proton nuclear magnetic resonance may explain the measured resonance, considering reorientation of the ammonium group by quantum tunneling of protons and a magnetic proton dipole-dipole intermolecular interaction model

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 ...

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. ...

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 ...

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 ...

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 ...

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 ...

Simulation of a resonant-type ring magnet power supply with multiple resonant cells and energy storage chokes

International Nuclear Information System (INIS)

Kim, J.M.S.; Blackmore, E.W.; Reiniger, K.W.

1992-01-01

For the TRIUMF KAON Factory Booster Ring, a resonant-type magnet power supply has been proposed for the dipole magnet excitation. The Booster Ring magnet power supply system based on resonant circuits, coupled with distributed energy make-up networks, is a complex system, sensitive to many system parameters. When multiple resonant cells, each with its own energy make-up network, are connected in a ring, it is very difficult to derive closed-form solutions to determine the operating conditions of the power supply system. A meaningful way to understand and analyze such a complex system is to use a simulation tool. This paper presents the analysis of operating conditions of the resonant-type ring magnet power supply with multiple resonant cells, using the circuit simulation tool, SPICE. The focus of the study is on the effect of circuit parameter variations in energy storage chokes

Soft X-ray resonant scattering from magnetic heterostructures

International Nuclear Information System (INIS)

Grabis, J.

2005-01-01

Heterogenous magnetic multilayers are of great interest both because of their relevance for technological applications and since they provide model systems to understand magnetic behavior and interactions. Soft x-ray resonant magnetic scattering (XRMS) allows to determine element-specific and depth-resolving information of the local magnetic order of such systems. Within the framework of the present thesis the diffractometer ALICE for soft XRMS has been constructed. XRMS measurements of two different physical systems are presented in this thesis: The antiferromagnetic and ferromagnetic order in interlayer exchange-coupled Fe/Cr(001) superlattices are studied as a function of the applied field by measuring the reflected intensity at different positions in reciprocal space. Thin films and multilayers of the Heusler compound Co 2 MnGe are studied by means of soft x-ray absorption spectroscopy, magnetic circular dichroism and resonant magnetic scattering

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

Artifacts Affecting Musculoskeletal Magnetic Resonance Imaging: Their Origins and Solutions.

Science.gov (United States)

Roth, Eira; Hoff, Michael; Richardson, Michael L; Ha, Alice S; Porrino, Jack

2016-01-01

Among articles within the radiology literature, few present the manifestations of magnetic resonance imaging artifacts in a clinically oriented manner. Recognizing such artifacts is imperative given the increasing clinical use of magnetic resonance imaging and the emphasis by the American Board of Radiology on practical physics applications. The purpose of this article is to present magnetic resonance physics principles visually and conceptually in the context of common musculoskeletal radiology artifacts and their solutions, described using nonmathematical explanations. Copyright © 2016 Elsevier Inc. All rights reserved.

Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

Science.gov (United States)

Dvinskikh, Sergey; Furo, Istvan

2010-05-01

While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative

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 ( ...

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 | ...

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 | ...

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 ...

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 ...

Inelastic tunneling spectroscopy for magnetic atoms and the Kondo resonance

International Nuclear Information System (INIS)

Goldberg, E C; Flores, F

2013-01-01

The interaction between a single magnetic atom and the metal environment (including a magnetic field) is analyzed by introducing an ionic Hamiltonian combined with an effective crystal-field term, and by using a Green-function equation of motion method. This approach describes the inelastic electron tunneling spectroscopy and the Kondo resonances as due to atomic spin fluctuations associated with electron co-tunneling processes between the leads and the atom. We analyze in the case of Fe on CuN the possible spin fluctuations between states with S = 2 and 3/2 or 5/2 and conclude that the experimentally found asymmetries in the conductance with respect to the applied bias, and its marked structures, are well explained by the 2↔3/2 spin fluctuations. The case of Co is also considered and shown to present, in contrast with Fe, a resonance at the Fermi energy corresponding to a Kondo temperature of 6 K. (paper)

Lymphoma of uterine cervix: magnetic resonance imaging findings

Energy Technology Data Exchange (ETDEWEB)

Kanaan, Daniel; Constantino, Carolina Pesce Lamas; Souza, Rodrigo Canellas de, E-mail: daniel.kanaan@hotmail.com [Department of Radiology, Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Parente, Daniella Braz [Instituto D' Or de Pesquisa e Ensino, Rio de Janeiro, RJ (Brazil)

2012-05-15

Lymphoma of the cervix is a rare disease. About 1.0% to 1.5% of extranodal lymphomas originates in the female genital tract. The clinical presentation of this condition is nonspecific and magnetic resonance imaging is important for diagnostic elucidation. The present report describes the case of a 80-year-old patient with lumbar pain, whose magnetic resonance imaging showed a large uterine mass. The final diagnosis was lymphoma. (author)

Maximum Likelihood Reconstruction for Magnetic Resonance Fingerprinting.

Science.gov (United States)

Zhao, Bo; Setsompop, Kawin; Ye, Huihui; Cauley, Stephen F; Wald, Lawrence L

2016-08-01

This paper introduces a statistical estimation framework for magnetic resonance (MR) fingerprinting, a recently proposed quantitative imaging paradigm. Within this framework, we present a maximum likelihood (ML) formalism to estimate multiple MR tissue parameter maps directly from highly undersampled, noisy k-space data. A novel algorithm, based on variable splitting, the alternating direction method of multipliers, and the variable projection method, is developed to solve the resulting optimization problem. Representative results from both simulations and in vivo experiments demonstrate that the proposed approach yields significantly improved accuracy in parameter estimation, compared to the conventional MR fingerprinting reconstruction. Moreover, the proposed framework provides new theoretical insights into the conventional approach. We show analytically that the conventional approach is an approximation to the ML reconstruction; more precisely, it is exactly equivalent to the first iteration of the proposed algorithm for the ML reconstruction, provided that a gridding reconstruction is used as an initialization.

Demonstration of Magnetic Dipole Resonances of Dielectric Nanospheres in the Visible Region

DEFF Research Database (Denmark)

Evlyukhin, A. B.; Novikov, S. M.; Zywietz, U.

2012-01-01

Strong resonant light scattering by individual spherical Si nanoparticles is experimentally demonstrated, revealing pronounced resonances associated with the excitation of magnetic and electric modes in these nanoparticles. It is shown that the low-frequency resonance corresponds to the magnetic...... dipole excitation. Due to high permittivity, the magnetic dipole resonance is observed in the visible spectral range for Si nanoparticles with diameters of similar to 200 nm, thereby opening a way to the realization of isotropic optical metamaterials with strong magnetic responses in the visible region....

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

Application of the annihilation and creation operators in magnetic resonance problems

International Nuclear Information System (INIS)

Nosel, W.

1981-01-01

Application of the annihilation and creation operators in the following problems is presented: in the resonance of the free spins in rotating and oscillating magnetic field, in the influence of the nonresonance magnetic fields on magnetic resonance, in the thermodynamics of the spins with dipolar interaction and in the nuclear magnetic relaxation. (author)

Method for increasing nuclear magnetic resonance signals in living biological tissue

International Nuclear Information System (INIS)

Krongrad, A.

1995-01-01

A method of enhancing a magnetic resonance comprising the steps of administering a quantity of a selected magnetic isotope to a living biological tissue at a concentration greater than the naturally occurring concentration of such isotope and detecting magnetic resonance signal from the administered magnetic isotope in the living biological tissue. (author)

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

Magnetic Barkhausen noise measurement by resonant coil method

Energy Technology Data Exchange (ETDEWEB)

Capo-Sanchez, J. [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n, 90500 Santiago de Cuba (Cuba)], E-mail: jcapo@usp.br; Padovese, L. [Departamento de Engenharia Mecanica, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2231, 05508-900 Sao Paulo (Brazil)

2009-09-15

This paper describes a powerful new technique for nondestructive evaluation of ferromagnetic material. A method has been developed for measuring magnetic Barkhausen signals under different coil resonance frequencies. The measurements allow one to establish the behavior relating the power spectral density maximum and the resonant coil frequency. Time-frequency analysis of Barkhausen signals puts in evidence the tuning regions for each coil, and allows clear identification of each contribution to the Barkhausen signal spectrum. This concept was used in order to evaluate the relation between the degree of plastic deformation in carbon steel samples, and the power spectral density maximum at different resonance frequencies. This result also makes it possible to the selectively modify measurement sensibility to the magnetic Barkhausen signal by using different resonance frequencies.

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 ...

Imaging of juvenile spondyloarthritis. Part II: Ultrasonography and magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Iwona Sudoł-Szopińska

2017-09-01

Full Text Available Juvenile spondyloarthropathies are mainly manifested by symptoms of peripheral arthritis and enthesitis. Early involvement of sacroiliac joints and spine is exceptionally rare in children; this usually happens in adulthood. Conventional radiographs visualize late inflammatory lesions. Early diagnosis is possible with the use of ultrasonography and magnetic resonance imaging. The first part of the article presented classifications and radiographic presentation of juvenile spondyloarthropathies. This part discusses changes seen on ultrasonography and magnetic resonance imaging. In patients with juvenile spondyloarthropathies, these examinations are conducted to diagnose inflammatory lesions in peripheral joints, tendon sheaths, tendons and bursae. Moreover, magnetic resonance also shows subchondral bone marrow edema, which is considered an early sign of inflammation. Ultrasonography and magnetic resonance imaging do not show specific lesions for any rheumatic disease. Nevertheless, they are conducted for early diagnosis, treatment monitoring and identifying complications. This article presents a spectrum of inflammatory changes and discusses the diagnostic value of ultrasonography and magnetic resonance imaging.

Simultaneous multislice magnetic resonance fingerprinting with low-rank and subspace modeling.

Science.gov (United States)

Bo Zhao; Bilgic, Berkin; Adalsteinsson, Elfar; Griswold, Mark A; Wald, Lawrence L; Setsompop, Kawin

2017-07-01

Magnetic resonance fingerprinting (MRF) is a new quantitative imaging paradigm that enables simultaneous acquisition of multiple magnetic resonance tissue parameters (e.g., T 1 , T 2 , and spin density). Recently, MRF has been integrated with simultaneous multislice (SMS) acquisitions to enable volumetric imaging with faster scan time. In this paper, we present a new image reconstruction method based on low-rank and subspace modeling for improved SMS-MRF. Here the low-rank model exploits strong spatiotemporal correlation among contrast-weighted images, while the subspace model captures the temporal evolution of magnetization dynamics. With the proposed model, the image reconstruction problem is formulated as a convex optimization problem, for which we develop an algorithm based on variable splitting and the alternating direction method of multipliers. The performance of the proposed method has been evaluated by numerical experiments, and the results demonstrate that the proposed method leads to improved accuracy over the conventional approach. Practically, the proposed method has a potential to allow for a 3× speedup with minimal reconstruction error, resulting in less than 5 sec imaging time per slice.

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.

Particle acceleration through the resonance of high magnetic field and high frequency electromagnetic wave

International Nuclear Information System (INIS)

Hong, Liu; He, X.T.; Chen, S.G.; Zhang, W.Y.; He, X.T.; Hong, Liu

2004-01-01

We propose a new particle acceleration mechanism. Electrons can be accelerated to relativistic energy within a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic field resonance acceleration (EMRA). We find that the electron acceleration depends not only on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave frequency. As the ratio approaches to unity, a clear resonance peak is observed, corresponding to the EMRA. Near the resonance regime, the strong magnetic fields still affect the electron acceleration dramatically. We derive an approximate analytical solution of the relativistic electron energy in adiabatic limit, which provides a full understanding of this phenomenon. In typical parameters of pulsar magnetospheres, the mechanism allows particles to increase their energies through the resonance of high magnetic field and high frequency electromagnetic wave in each electromagnetic wave period. The energy spectra of the accelerated particles exhibit the synchrotron radiation behavior. These can help to understand the remaining emission of high energy electron from radio pulsar within supernova remnant. The other potential application of our theory in fast ignition scheme of inertial confinement fusion is also discussed. (authors)

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 ...

Magnetic resonance imaging of generalised musculo-skeletal diseases

International Nuclear Information System (INIS)

Kaiser, W.A.; Schalke, B.C.G.

1989-01-01

The results presented are drawn from 320 examinations by NMR imaging of patients with various systemic muscle diseases (dystrophies, myositides, metabolic disorders), and are interpreted so as to explain the relevant characteristic distribution patterns of the degenerative processes in the femoral musculature as shown by the NMR images. Four basic patterns are presented according to the criteria homogeneous-heterogeneous and symmetric-asymmetric, and the diseases identified by the differential diagnostic evaluation are discussed. The optimum measuring conditions for magnetic resonance imaging of the musculature are given, and the specific magnetic resonance criteria of myositides, neurogenic myopathies, myofonous dystrophies, c.n. polio, morbus Pompe, familial hypokalemic paralysis, centronuclear mypathy, morbus Duchenne are explained. The significance of NMR imaging with regard to biopsy or therapy planning is discussed, and magnetic resonance examination is recommended to be applied prior to biopsy. (orig.) [de

Ultra-small v-shaped gold split ring resonators for biosensing using fundamental magnetic resonance in the visible spectrum

Science.gov (United States)

Mauluidy Soehartono, Alana; Mueller, Aaron David; Tobing, Landobasa Yosef Mario; Chan, Kok Ken; Zhang, Dao Hua; Yong, Ken-Tye

2017-10-01

Strong light localization within metal nanostructures occurs by collective oscillations of plasmons in the form of electric and magnetic resonances. This so-called localized surface plasmon resonance (LSPR) has gained much interest in the development of low-cost sensing platforms in the visible spectrum. However, demonstrations of LSPR-based sensing are mostly limited to electric resonances due to the technological limitations for achieving magnetic resonances in the visible spectrum. In this work, we report the first demonstration of LSPR sensing based on fundamental magnetic resonance in the visible spectrum using ultrasmall gold v-shaped split ring resonators. Specifically, we show the ability for detecting adsorption of bovine serum albumin and cytochrome c biomolecules at monolayer levels, and the selective binding of protein A/G to immunoglobulin G.

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

Rheo-NMR: nuclear magnetic resonance and the rheology of complex fluids

International Nuclear Information System (INIS)

Callaghan, Paul T.

1999-01-01

The application of nuclear magnetic resonance methods to the study of complex fluids under shearing and extensional flows is reviewed. Both NMR velocimetry and spectroscopy approaches are discussed while specific systems studied include polymer melts, rigid rod and random coil polymers in solution, lyotropic and thermotropic liquid crystals and liquid crystalline polymers, and wormlike micelles. Reference is made to food systems. (author)

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

Mesoscopic Magnetic Resonance Spectroscopy with a Remote Spin Sensor

Science.gov (United States)

Xie, Tianyu; Shi, Fazhan; Chen, Sanyou; Guo, Maosen; Chen, Yisheng; Zhang, Yixing; Yang, Yu; Gao, Xingyu; Kong, Xi; Wang, Pengfei; Tateishi, Kenichiro; Uesaka, Tomohiro; Wang, Ya; Zhang, Bo; Du, Jiangfeng

2018-06-01

Quantum sensing based on nitrogen-vacancy (N -V ) centers in diamond has been developed as a powerful tool for microscopic magnetic resonance. However, the reported sensor-to-sample distance is limited within tens of nanometers resulting from the cubic decrease of the signal of spin fluctuation with the increasing distance. Here we extend the sensing distance to tens of micrometers by detecting spin polarization rather than spin fluctuation. We detect the mesoscopic magnetic resonance spectra of polarized electrons of a pentacene-doped crystal, measure its two typical decay times, and observe the optically enhanced spin polarization. This work paves the way for the N -V -based mesoscopic magnetic resonance spectroscopy and imaging at ambient conditions.

Upper Hybrid Resonance of Microwaves with a Large Magnetized Plasma Sheet

International Nuclear Information System (INIS)

Huo Wenqing; Guo Shijie; Ding Liang; Xu Yuemin

2013-01-01

A large magnetized plasma sheet with size of 60 cm × 60 cm × 2 cm was generated by a linear hollow cathode discharge under the confinement of a uniform magnetic field generated by a Helmholtz Coil. The microwave transmission characteristic of the plasma sheet was measured for different incident frequencies, in cases with the electric field polarization of the incident microwave either perpendicular or parallel to the magnetic field. In this measurement, parameters of the plasma sheet were changed by varying the discharge current and magnetic field intensity. In the experiment, upper hybrid resonance phenomena were observed when the electric field polarization of the incident wave was perpendicular to the magnetic field. These resonance phenomena cannot be found in the case of parallel polarization incidence. This result is consistent with theoretical consideration. According to the resonance condition, the electron density values at the resonance points are calculated under various experimental conditions. This kind of resonance phenomena can be used to develop a specific method to diagnose the electron density of this magnetized plasma sheet apparatus. Moreover, it is pointed out that the operating parameters of the large plasma sheet in practical applications should be selected to keep away from the upper hybrid resonance point to prevent signals from polarization distortion

Fano coil-type resonances: a plasmonic tool for the magnetic field manipulation (Conference Presentation)

Science.gov (United States)

Panaro, Simone; Proietti Zaccaria, Remo; Toma, Andrea

2017-02-01

Spintronics and spin-based technology rely on the ultra-fast unbalance of the electronic spin population in quite localized spatial regions. However, as a matter of fact, the low susceptibility of conventional materials at high frequencies strongly limits these phenomena, rendering the efficiency of magnetically active devices insufficient for application purposes. Among the possible strategies which can be envisaged, plasmonics offers a direct approach to increase the effect of local electronic unbalancing processes. By confining and enhancing free radiation in nm-size spatial regions, plasmonic nano-assemblies have demonstrated to support very intense electric and magnetic hot-spots. In particular, very recent studies have proven the fine control of magnetic fields in Fano resonance condition. The near-field-induced out-of-phase oscillation of localized surface plasmons has manifested itself with the arising of magnetic sub-diffractive hot-spots. Here, we show how this effect can be further boosted in the mid-infrared regime via the introduction of higher order plasmonic modes. The investigated system, namely Moon Trimer Resonator (MTR), combines the high efficiency of a strongly coupled nano-assembly in Fano interferential condition with the elevated tunability of the quadrupolar resonance supported by a moon-like geometry. The fine control of the apical gap in this unique nanostructure, characterizes a plasmonic device able to tune its resonance without any consequence on the magnetic hot-spot size, thus enabling an efficient squeezing in the infrared.

Resonant inverter supplied Interior Permanent Magnet (IPM) motor ...

African Journals Online (AJOL)

In this paper, rotor position in relation to the resonant frequency component current in the stator winding of DC-voltage link resonant inverter supplied Interior Permanent Magnet (IPM) motor has been developed. Six reference frames are used to relate the rotor position angle to the resonant frequency component current ...

A logic programming and statistical systems approach for tissue characterization in magnetic resonance imaging

International Nuclear Information System (INIS)

Levy, G.C.; Dudewicz, E.J.; Harner, T.J.

1989-01-01

The main research goal has been to evalute significant factors affecting the in vivo magnetic resonance imaging (MRI) parameters R 1 , T 2 , and 1 H density. This approach differs significantly from other such projects in that the experimental data analysis is being performed while concurrently developing automated, computer-aided analysis software for such MRI tissue parameters. In the experimental portion of the project, statistical analyses, and a heuristic minimum/maximum discriminant analysis algorithm have been explored. Both methods have been used to classify tissue types from 1.5 Tesla transaxial MR images of the human brain. The developing program, written in the logic programming language Prolog, similar in a number of ways to many existing expert systems now in use for other medical applications; inclusion of the underlying statistical data base and advanced statistical analyses is the main differentiating feature of the current approach. First results indicate promising classification accuracy of various brain tissues such as gray and white matter, as well as differentiation of different types of gray matter and white matter (e.g.: caudate-nucleus vs. thalamus, both representatives of gray matter; and, cortical white matter vs. internal capsule as representative of white matter). Taking all four tissue types together, the percentage of correct classifications ranges from 73 to 87%. (author)

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.

Ferromagnetic linewidth measurements employing electrodynamic model of the magnetic plasmon resonance

Science.gov (United States)

Krupka, Jerzy; Aleshkevych, Pavlo; Salski, Bartlomiej; Kopyt, Pawel

2018-02-01

The mode of uniform precession, or Kittel mode, in a magnetized ferromagnetic sphere, has recently been proven to be the magnetic plasmon resonance. In this paper we show how to apply the electrodynamic model of the magnetic plasmon resonance for accurate measurements of the ferromagnetic resonance linewidth ΔH. Two measurement methods are presented. The first one employs Q-factor measurements of the magnetic plasmon resonance coupled to the resonance of an empty metallic cavity. Such coupled modes are known as magnon-polariton modes, i.e. hybridized modes between the collective spin excitation and the cavity excitation. The second one employs direct Q-factor measurements of the magnetic plasmon resonance in a filter setup with two orthogonal semi-loops used for coupling. Q-factor measurements are performed employing a vector network analyser. The methods presented in this paper allow one to extend the measurement range of the ferromagnetic resonance linewidth ΔH well beyond the limits of the commonly used measurement standards in terms of the size of the samples and the lowest measurable linewidths. Samples that can be measured with the newly proposed methods may have larger size as compared to the size of samples that were used in the standard methods restricted by the limits of perturbation theory.

Imaging of the hip joint. Computed tomography versus magnetic resonance imaging

Science.gov (United States)

Lang, P.; Genant, H. K.; Jergesen, H. E.; Murray, W. R.

1992-01-01

The authors reviewed the applications and limitations of computed tomography (CT) and magnetic resonance (MR) imaging in the assessment of the most common hip disorders. Magnetic resonance imaging is the most sensitive technique in detecting osteonecrosis of the femoral head. Magnetic resonance reflects the histologic changes associated with osteonecrosis very well, which may ultimately help to improve staging. Computed tomography can more accurately identify subchondral fractures than MR imaging and thus remains important for staging. In congenital dysplasia of the hip, the position of the nonossified femoral head in children less than six months of age can only be inferred by indirect signs on CT. Magnetic resonance imaging demonstrates the cartilaginous femoral head directly without ionizing radiation. Computed tomography remains the imaging modality of choice for evaluating fractures of the hip joint. In some patients, MR imaging demonstrates the fracture even when it is not apparent on radiography. In neoplasm, CT provides better assessment of calcification, ossification, and periosteal reaction than MR imaging. Magnetic resonance imaging, however, represents the most accurate imaging modality for evaluating intramedullary and soft-tissue extent of the tumor and identifying involvement of neurovascular bundles. Magnetic resonance imaging can also be used to monitor response to chemotherapy. In osteoarthrosis and rheumatoid arthritis of the hip, both CT and MR provide more detailed assessment of the severity of disease than conventional radiography because of their tomographic nature. Magnetic resonance imaging is unique in evaluating cartilage degeneration and loss, and in demonstrating soft-tissue alterations such as inflammatory synovial proliferation.

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...

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...

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 ( ...

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 ...

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 ...

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

Harmonic detection of magnetic resonance for sensitivity improvement of optical atomic magnetometers

Energy Technology Data Exchange (ETDEWEB)

Ranjbaran, M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Tehranchi, M.M., E-mail: teranchi@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hamidi, S.M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Khalkhali, S.M.H. [Physics Department, Kharazmi University, Tehran (Iran, Islamic Republic of)

2017-02-15

Highly sensitive atomic magnetometers use optically detected magnetic resonance of atomic spins to measure extremely weak magnetic field changes. The magnetometer sensitivity is directly proportional to the ratio of intensity to line-shape of the resonance signal. To obtain narrower resonance signal, we implemented harmonic detection of magnetic resonance method in M{sub x} configuration. The nonlinear spin polarization dynamics in detection of the higher harmonics were employed in phenomenological Bloch equations. The measured and simulated harmonic components of the resonance signals in frequency domain yielded significantly narrower line-width accompanying much improved sensitivity. Our results confirm the sensitivity improvement by a factor of two in optical atomic magnetometer via second harmonic signal which can open a new insight in the weak magnetic field measurement system design. - Highlights: • Highly sensitive atomic magnetometers have been used to measure weak magentic filed. • To obtain narrower resonance signal, we impalnted harmonic detection of magnetic resonance. • The nonlinear spin polarization dynamics in detetion of the higher harmonics were imployed.

Magnetic resonance spectroscopy and imaging in cerebral ischemia

International Nuclear Information System (INIS)

Rijen, P.C. van.

1991-01-01

In-vivo proton and phosphorus magnetic resonance spectroscopy was used to detect changes in cerebral metabolism during ischemia and other types of metabolic stress. Magnetic resonance imaging was performed in an animal model to observe morphological alterations during focal cerebral ischemia. Spectroscopy was performed in animal models with global ischemia, in volunteers during hyperventilation and pharmaco-logically altered cerebral perfusion, and in patients with acute and prolonged focal cerebral ischemia. (author). 396 refs.; 44 figs.; 14 tabs

Low losses left-handed materials with optimized electric and magnetic resonance

Science.gov (United States)

Zhou, Xin; Liu, Yahong; Zhao, Xiaopeng

2010-03-01

We propose that the losses in left-handed materials (LHMs) can be significantly affected by changing the coupling relationship between electric and magnetic resonance. A double bowknot shaped structure (DBS) is used to construct the LHMs. And the magnetic resonance of the DBS, which resonated in the case of lower and higher frequencies than the electric resonant dip, is studied in simulation and experiment by tailoring the structural parameters. The case of magnetic resonance located at low electric resonance frequencies band is confirmed to have relatively low losses. Using full wave simulation of prism shaped structure composed of DBS unit cells, we prove the negative refraction behavior in such a frame. This study can serve as a guide for designing other similar metal-dielectric-metal (MDM) in low losses at terahertz or higher frequencies.

Proceedings of the 4. Brazilian meeting on magnetic resonance. Abstracts

International Nuclear Information System (INIS)

1996-01-01

This publication contains the abstracts of the papers presented during the 4. Brazilian meeting on magnetic resonance and also during the Course on advances in nuclear magnetic resonance. Works on the areas of materials, rare earths, polymers, structural chemical analysis and NMR spectra are presented

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

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

The galenic venous system: Surgical anatomy and its angiographic and magnetic resonance venographic correlations

International Nuclear Information System (INIS)

Kilic, Tuerker; Ozduman, Koray; Cavdar, Safiye; Oezek, M. Memet; Pamir, M. Necmettin

2005-01-01

Objective: This study aims at evaluating the adequacy of digital subtraction angiography and magnetic resonance venography in imaging of the galenic venous system for surgical planning of approaches to the pineal region. Anatomical dissections were carried out in 10 cadavers of several age groups and these were compared to imaging findings in 10 living subjects. Methods: The presence or absence of 10 predetermined veins or vein groupings belonging to the galenic venous system were prospectively analyzed in 10 cadaver dissections and imaging findings of 10 age matched human subjects. The studied vessels were the vein of galen, the internal cerebral veins, both basal vein of Rosenthals, internal occipital vein, occipitotemporal veins, precentral cerebellar veins, tectal veins, pineal veins, superior vermian veins (including superior cerebellar veins (SCVs)) and posterior pericallosal veins. Each of the subjects had both digital subtraction angiography and magnetic resonance venography studies performed. Diagnostic digital subtraction angiography was performed using the transfemoral route and the venous phase was used for the study. Magnetic resonance venography was performed in 1.5 T MRI equipment using the 2D-TOF sequence. All studies were reported to be normal. Results: There was wide variation in the anatomy of the galenic venous system. There were interpersonal, intrapersonal and age related variations. Both the digital subtraction angiography and the magnetic resonance venography were efficient at demonstrating large veins. However, smaller veins were less readily demonstrated in either study. The general sensitivities of the digital subtraction angiography and the magnetic resonance venography for the galenic venous system were 45.5% and 32.5%, respectively. Surgically important veins were missed in most studies. Conclusions: Anatomically, the galenic venous system is highly variable. This variability is caused by interpersonal, intrapersonal and age related

The galenic venous system: Surgical anatomy and its angiographic and magnetic resonance venographic correlations

Energy Technology Data Exchange (ETDEWEB)

Kilic, Tuerker [Marmara University, Department of Neurosurgery, PK 53, Maltepe, 81532 Istanbul (Turkey) and Marmara University, Department of Anatomy, Istanbul (Turkey)]. E-mail: turkilic@tnn.net; Ozduman, Koray [Marmara University, Department of Neurosurgery, PK 53, Maltepe, 81532 Istanbul (Turkey); Cavdar, Safiye [Marmara University, Department of Anatomy, Istanbul (Turkey); Oezek, M. Memet [Marmara University, Department of Neurosurgery, PK 53, Maltepe, 81532 Istanbul (Turkey); Pamir, M. Necmettin [Marmara University, Department of Neurosurgery, PK 53, Maltepe, 81532 Istanbul (Turkey)

2005-11-01

Objective: This study aims at evaluating the adequacy of digital subtraction angiography and magnetic resonance venography in imaging of the galenic venous system for surgical planning of approaches to the pineal region. Anatomical dissections were carried out in 10 cadavers of several age groups and these were compared to imaging findings in 10 living subjects. Methods: The presence or absence of 10 predetermined veins or vein groupings belonging to the galenic venous system were prospectively analyzed in 10 cadaver dissections and imaging findings of 10 age matched human subjects. The studied vessels were the vein of galen, the internal cerebral veins, both basal vein of Rosenthals, internal occipital vein, occipitotemporal veins, precentral cerebellar veins, tectal veins, pineal veins, superior vermian veins (including superior cerebellar veins (SCVs)) and posterior pericallosal veins. Each of the subjects had both digital subtraction angiography and magnetic resonance venography studies performed. Diagnostic digital subtraction angiography was performed using the transfemoral route and the venous phase was used for the study. Magnetic resonance venography was performed in 1.5 T MRI equipment using the 2D-TOF sequence. All studies were reported to be normal. Results: There was wide variation in the anatomy of the galenic venous system. There were interpersonal, intrapersonal and age related variations. Both the digital subtraction angiography and the magnetic resonance venography were efficient at demonstrating large veins. However, smaller veins were less readily demonstrated in either study. The general sensitivities of the digital subtraction angiography and the magnetic resonance venography for the galenic venous system were 45.5% and 32.5%, respectively. Surgically important veins were missed in most studies. Conclusions: Anatomically, the galenic venous system is highly variable. This variability is caused by interpersonal, intrapersonal and age related

Adjunctive role of preoperative liver magnetic resonance imaging for potentially resectable pancreatic cancer.

Science.gov (United States)

Kim, Hyoung Woo; Lee, Jong-Chan; Paik, Kyu-Hyun; Kang, Jingu; Kim, Young Hoon; Yoon, Yoo-Seok; Han, Ho-Seong; Kim, Jaihwan; Hwang, Jin-Hyeok

2017-06-01

The adjunctive role of magnetic resonance imaging of the liver before pancreatic ductal adenocarcinoma has been unclear. We evaluated whether the combination of hepatic magnetic resonance imaging with multidetector computed tomography using a pancreatic protocol (pCT) could help surgeons select appropriate candidates and decrease the risk of early recurrence. We retrospectively enrolled 167 patients in whom complete resection was achieved without grossly visible residual tumor; 102 patients underwent pCT alone (CT group) and 65 underwent both hepatic magnetic resonance imaging and pCT (magnetic resonance imaging group). By adding hepatic magnetic resonance imaging during preoperative evaluation, hepatic metastases were newly discovered in 3 of 58 patients (5%) without hepatic lesions on pCT and 17 of 53 patients (32%) with indeterminate hepatic lesions on pCT. Patients with borderline resectability, a tumor size >3 cm, or preoperative carbohydrate antigen 19-9 level >1,000 U/mL had a greater rate of hepatic metastasis on subsequent hepatic magnetic resonance imaging. Among 167 patients in whom R0/R1 resection was achieved, the median overall survival was 18.2 vs 24.7 months (P = .020) and the disease-free survival was 8.5 vs 10.0 months (P = .016) in the CT and magnetic resonance imaging groups, respectively (median follow-up, 18.3 months). Recurrence developed in 82 (80%) and 43 (66%) patients in the CT and magnetic resonance imaging groups, respectively. The cumulative hepatic recurrence rate was greater in the CT group than in the magnetic resonance imaging group (P magnetic resonance imaging should be considered in patients with potentially resectable pancreatic ductal adenocarcinoma, especially those with high tumor burden. Copyright © 2017 Elsevier Inc. All rights reserved.

Multiple systems atrophy: Differentiation and findings by Magnetic resonance

International Nuclear Information System (INIS)

Vargas Velez, Sergio Alberto; Alzate Betancur, Catalina Maria

2006-01-01

Multiple system atrophy (MSA) is a neuro degenerative disorder of undetermined cause, characterized clinically by Parkinson's, autonomic, cerebellar or pyramidal sing and symptoms. lts differentiation from Parkinson's disease may be difficult, mainly in the early stages owing to overlapping features. Magnetic resonance imaging has demonstrated usefulness in MSA diagnosis and in differentiation with Parkinson's disease. One case with magnetic resonance findings is described

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.)

The introduction of clinical magnetic resonance imaging in Australia

International Nuclear Information System (INIS)

Sorby, W.; Baddeley, H.

1986-01-01

Magnetic resonance imaging is a new, but expensive, modality that is being introduced into clinical use in Australia. While it promises increased safety and accuracy in many situations, its precise role when compared with computed tomography and other modalities is not fully established. Therefore, a Government financed evaluation of costs and efficacy of magnetic resonance imaging units in five teaching hospitals is to be conducted over two years (1986-1988). Experience with the introduction of computed tomography to Australia and other nations has revealed difficulties in the evaluation by conventional methods of a diagnostic technology that is improving rapidly; it is to be hoped that a systematic evaluation of the clinical applications of magnetic resonance imaging will be more achievable and useful

Magnetic resonance neurography for the identification of pudendal neuralgia

Directory of Open Access Journals (Sweden)

Claudia P. Cejas

2017-06-01

Full Text Available The pudendal nerve entrapment is an entity understudied by diagnosis imaging. Various causes are recognized in relation to difficult labors, rectal, perineal, urological and gynecological surgery, pelvic trauma fracture, bones tumors and compression by tumors or pelvic pseudotumors. Pudendal neuropathy should be clinically suspected, and confirmed by different methods such as electrofisiological testing: evoked potentials, terminal motor latency test and electromyogram, neuronal block and magnetic resonance imaging. The radiologist should be acquainted with the complex anatomy of the pelvic floor, particularly on the path of pudendal nerve studied by magnetic resonance imaging. High resolution magnetic resonance neurography should be used as a complementary diagnostic study along with clinical and electrophysiological examinations in patients with suspected pudendal nerve neuralgia.

Studies of magnetic resonance in anemia of hematies falciformes

International Nuclear Information System (INIS)

Lores Guevara, Manuel Arsenio; Balcom, Bruce John; Cabal Mirabal, Carlos

2012-01-01

Magnetic Resonance applications to the study of Sickle Cell Disease are analyzed using classical procedures and Unilateral Magnetic Resonance. Hemoglobin and whole blood samples were obtained from healthy individual and patients with Sickle Cell Anemia to be used as samples. Classical pulse sequence as spin echo and inversion recovery were used in the experimental studies, the STEPR method was used for EPR spectrometric determinations. The results show the possibility of NMR methods to follow the molecular process causing the disease and allows to present quantitative procedures to estimate the clinical state of the patients and the results of clinical options. We present the Unilateral Magnetic Resonance as a new method to study Sickle Cell disease considering its portability and new possibilities as new image method

Magnetic resonance imaging of living systems by remote detection

Science.gov (United States)

Wemmer, David; Pines, Alexander; Bouchard, Louis; Xu, Shoujun; Harel, Elad; Budker, Dmitry; Lowery, Thomas; Ledbetter, Micah

2013-10-29

A novel approach to magnetic resonance imaging is disclosed. Blood flowing through a living system is prepolarized, and then encoded. The polarization can be achieved using permanent or superconducting magnets. The polarization may be carried out upstream of the region to be encoded or at the place of encoding. In the case of an MRI of a brain, polarization of flowing blood can be effected by placing a magnet over a section of the body such as the heart upstream of the head. Alternatively, polarization and encoding can be effected at the same location. Detection occurs at a remote location, using a separate detection device such as an optical atomic magnetometer, or an inductive Faraday coil. The detector may be placed on the surface of the skin next to a blood vessel such as a jugular vein carrying blood away from the encoded region.

On the Floquet–Magnus expansion: Applications in solid-state nuclear magnetic resonance and physics

Energy Technology Data Exchange (ETDEWEB)

Mananga, Eugene Stephane, E-mail: emananga@gradcenter.cuny.edu [Harvard Medical School and Massachusetts General Hospital, Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging Physics, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114 (United States); Charpentier, Thibault, E-mail: thibault.charpentier@cea.fr [Commissariat à l’Energie Atomique, IRAMIS, Service interdisciplinaire sur les systèmes moléculaires et matériaux, CEA/CNRS UMR 3299, 91191, Gif-sur-Yvette (France)

2016-01-22

Theoretical approaches are useful and powerful tools for more accurate and efficient spin dynamics simulation to understand experiments and devising new RF pulse sequence in nuclear magnetic resonance. Solid-state NMR is definitely a timely topic or area of research, and not many papers on the respective theories are available in the literature of nuclear magnetic resonance or physics reports. This report presents the power and the salient features of the promising theoretical approach called Floquet–Magnus expansion that is helpful to describe the time evolution of the spin system at all times in nuclear magnetic resonance. The report presents a broad view of algorithms of spin dynamics, based on promising and useful theory of Floquet–Magnus expansion. This theory provides procedures to control and describe the spin dynamics in solid-state NMR. Major applications of the Floquet–Magnus expansion are illustrated by simple solid-state NMR and physical applications such as in nuclear, atomic, molecular physics, and quantum mechanics, NMR, quantum field theory and high energy physics, electromagnetism, optics, general relativity, search of periodic orbits, and geometric control of mechanical systems. The aim of this report is to bring to the attention of the spin dynamics community, the bridge that exists between solid-state NMR and other related fields of physics and applied mathematics. This review article also discusses future potential theoretical directions in solid-state NMR.

Proceedings of the nuclear magnetic resonance user meeting

International Nuclear Information System (INIS)

1987-01-01

Studies on utilization of nuclear magnetic resonance, such as: chemical analysis in complexes and organic compounds; structures and magnetic properties of solids; construction of images and; spectrometer designs, are presented. (M.C.K.) [pt

Laboratory studies of the dynamic of resonance cones formation in magnetized plasmas

Energy Technology Data Exchange (ETDEWEB)

Nazarov, V. V.; Starodubtsev, M. V.; Kostrov, A. V. [Russian Academy of Sciences, Institute of Applied Physics, Nizhny Novgorod (Russian Federation)

2013-03-15

The paper is devoted to experimental studies of formation of resonance cones in magnetized plasmas by pulsed RF source in the lower-hybrid (whistler) and the upper-hybrid frequency ranges. It is shown that in both frequency ranges, resonance cones exhibit similar dynamics after switching-on the RF source: at first, wide maxima of radiation are formed in non-resonance directions, which then become narrower, with their direction approaching the resonance one. While the resonance cones are being formed, one observes a fine structure in the form of secondary radiation maxima. It is shown that the characteristic formation time of stationary resonance cones is determined by the minimal value of the group velocity of the quasi-electrostatic waves excited by the antenna. In the low-temperature plasma, this value is limited in the lower-hybrid frequency range by the spatial spectrum of the emitting antenna and in the upper-hybrid range, by the effects of spatial plasma dispersion.

Magnetic resonance angiography vs. angiography in tetralogy of Fallot.

Science.gov (United States)

Rao, Uppalapati Venkateswara; Vanajakshamma, Velam; Rajasekhar, Durgaprasad; Lakshmi, Amancharla Yadagiri; Reddy, Reddivari Niranjan

2013-08-01

: To determine whether gadolinium-enhanced three-dimensional magnetic resonance angiography can provide a noninvasive alternative to diagnostic catheterization for evaluation of pulmonary artery anatomy in tetralogy of Fallot. Thirty-five consecutive patients with tetralogy of Fallot, who attended the cardiology outpatient department between January 2008 and December 2009, were included in the study. There were 21 males and 14 females, with a mean age of 9 ± 4.15 years (range, 3-21 years). Thirty-two patients had tetralogy of Fallot with varying severities of valvular and infundibular stenosis. Three patients had tetralogy of Fallot with pulmonary atresia. All patients underwent both cardiac catheterization with X-ray angiography and 3-dimensional magnetic resonance angiography within one month. Measurements of right and left pulmonary arteries and aortopulmonary collaterals were equal by both methods. There was a good correlation between magnetic resonance angiography and catheterization measurements of branch pulmonary arteries. Gadolinium-enhanced three-dimensional magnetic resonance angiography can be used as a reliable noninvasive alternative to X-ray cineangiography for delineation of pulmonary arterial anatomy in sick infants and young children, obviating the need for catheterization.

Light-free magnetic resonance force microscopy for studies of electron spin polarized systems

International Nuclear Information System (INIS)

Pelekhov, Denis V.; Selcu, Camelia; Banerjee, Palash; Chung Fong, Kin; Chris Hammel, P.; Bhaskaran, Harish; Schwab, Keith

2005-01-01

Magnetic resonance force microscopy is a scanned probe technique capable of three-dimensional magnetic resonance imaging. Its excellent sensitivity opens the possibility for magnetic resonance studies of spin accumulation resulting from the injection of spin polarized currents into a para-magnetic collector. The method is based on mechanical detection of magnetic resonance which requires low noise detection of cantilever displacement; so far, this has been accomplished using optical interferometry. This is undesirable for experiments on doped silicon, where the presence of light is known to enhance spin relaxation rates. We report a non-optical displacement detection scheme based on sensitive microwave capacitive readout

Systematic comparison and reconstruction of sea urchin (Echinoidea internal anatomy: a novel approach using magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Mueller Susanne

2008-07-01

Full Text Available Abstract Background Traditional comparative morphological analyses and subsequent three-dimensional reconstructions suffer from a number of drawbacks. This is particularly evident in the case of soft tissue studies that are technically demanding, time-consuming, and often prone to produce artefacts. These problems can partly be overcome by employing non-invasive, destruction-free imaging techniques, in particular micro-computed tomography or magnetic resonance imaging. Results Here, we employed high-field magnetic resonance imaging techniques to gather numerous data from members of a major marine invertebrate taxon, the sea urchins (Echinoidea. For this model study, 13 of the 14 currently recognized high-ranking subtaxa (orders of this group of animals were analyzed. Based on the acquired datasets, interactive three-dimensional models were assembled. Our analyses reveal that selected soft tissue characters can even be used for phylogenetic inferences in sea urchins, as exemplified by differences in the size and shape of the gastric caecum found in the Irregularia. Conclusion The main focus of our investigation was to explore the possibility to systematically visualize the internal anatomy of echinoids obtained from various museum collections. We show that, in contrast to classical preparative procedures, magnetic resonance imaging can give rapid, destruction-free access to morphological data from numerous specimens, thus extending the range of techniques available for comparative studies of invertebrate morphology.

Magnetic resonance imaging-compatible tactile sensing device based on a piezoelectric array.

Science.gov (United States)

Hamed, Abbi; Masamune, Ken; Tse, Zion Tsz Ho; Lamperth, Michael; Dohi, Takeyoshi

2012-07-01

Minimally invasive surgery is a widely used medical technique, one of the drawbacks of which is the loss of direct sense of touch during the operation. Palpation is the use of fingertips to explore and make fast assessments of tissue morphology. Although technologies are developed to equip minimally invasive surgery tools with haptic feedback capabilities, the majority focus on tissue stiffness profiling and tool-tissue interaction force measurement. For greatly increased diagnostic capability, a magnetic resonance imaging-compatible tactile sensor design is proposed, which allows minimally invasive surgery to be performed under image guidance, combining the strong capability of magnetic resonance imaging soft tissue and intuitive palpation. The sensing unit is based on a piezoelectric sensor methodology, which conforms to the stringent mechanical and electrical design requirements imposed by the magnetic resonance environment The sensor mechanical design and the device integration to a 0.2 Tesla open magnetic resonance imaging scanner are described, together with the device's magnetic resonance compatibility testing. Its design limitations and potential future improvements are also discussed. A tactile sensing unit based on a piezoelectric sensor principle is proposed, which is designed for magnetic resonance imaging guided interventions.

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.

Resonant diffuse X-ray scattering from magnetic multilayers

International Nuclear Information System (INIS)

Spezzani, Carlo; Torelli, Piero; Delaunay, Renaud; Hague, C.F.; Petroff, Frederic; Scholl, Andreas; Gullikson, E.M.; Sacchi, Maurizio

2004-01-01

We have measured field-dependent resonant diffuse scattering from a magnetoresistive Co/Cu multilayer. We have observed that the magnetic domain size in zero field depends on the magnetic history of the sample. The results of the X-ray scattering analysis have been compared to PEEM images of the magnetic domains

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.)

Magnetic resonance imaging of the elbow. Part I: Normal anatomy, imaging technique, and osseous abnormalities

International Nuclear Information System (INIS)

Kijowski, Richard; Tuite, Michael; Sanford, Matthew

2004-01-01

Part I of this comprehensive review on magnetic resonance imaging of the elbow discusses normal elbow anatomy and the technical factors involved in obtaining high-quality magnetic resonance images of the elbow. Part I also discusses the role of magnetic resonance imaging in evaluating patients with osseous abnormalities of the elbow. With proper patient positioning and imaging technique, magnetic resonance imaging can yield high-quality multiplanar images which are useful in evaluating the osseous structures of the elbow. Magnetic resonance imaging can detect early osteochondritis dissecans of the capitellum and can be used to evaluate the size, location, stability, and viability of the osteochondritis dissecans fragment. Magnetic resonance imaging can detect early stress injury to the proximal ulna in athletes. Magnetic resonance imaging can detect radiographically occult fractures of the elbow in both children and adults. Magnetic resonance imaging is also useful in children to further evaluate elbow fractures which are detected on plain-film radiographs. (orig.)

Fast 3D magnetic resonance fingerprinting for a whole-brain coverage.

Science.gov (United States)

Ma, Dan; Jiang, Yun; Chen, Yong; McGivney, Debra; Mehta, Bhairav; Gulani, Vikas; Griswold, Mark

2018-04-01

The purpose of this study was to accelerate the acquisition and reconstruction time of 3D magnetic resonance fingerprinting scans. A 3D magnetic resonance fingerprinting scan was accelerated by using a single-shot spiral trajectory with an undersampling factor of 48 in the x-y plane, and an interleaved sampling pattern with an undersampling factor of 3 through plane. Further acceleration came from reducing the waiting time between neighboring partitions. The reconstruction time was accelerated by applying singular value decomposition compression in k-space. Finally, a 3D premeasured B 1 map was used to correct for the B 1 inhomogeneity. The T 1 and T 2 values of the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology MRI phantom showed a good agreement with the standard values, with an average concordance correlation coefficient of 0.99, and coefficient of variation of 7% in the repeatability scans. The results from in vivo scans also showed high image quality in both transverse and coronal views. This study applied a fast acquisition scheme for a fully quantitative 3D magnetic resonance fingerprinting scan with a total acceleration factor of 144 as compared with the Nyquist rate, such that 3D T 1 , T 2 , and proton density maps can be acquired with whole-brain coverage at clinical resolution in less than 5 min. Magn Reson Med 79:2190-2197, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Impact of magnetic resonance imaging on preoperative planning for breast cancer surgery.

Science.gov (United States)

Law, Y; Cheung, Polly S Y; Lau, Silvia; Lo, Gladys G

2013-08-01

To review the impact of preoperative breast magnetic resonance imaging on the management of planned surgery, and the appropriateness of any resulting alterations. Retrospective review. A private hospital in Hong Kong. PATIENTS; For the 147 consecutive biopsy-proven breast cancer patients who underwent preoperative magnetic resonance imaging to determine tumour extent undergoing operation by a single surgeon between 1 January 2006 and 31 December 2009, the impact of magnetic resonance imaging findings was reviewed in terms of management alterations and their appropriateness. The most common indication for breast magnetic resonance imaging was the presence of multiple indeterminate shadows on ultrasound scans (53%), followed by ill-defined border of the main tumour on ultrasound scans (19%). In 66% (97 out of 147) of the patients, the extent of the operation was upgraded. Upgrading entailed: lumpectomy to wider lumpectomy (23 out of 97), lumpectomy to mastectomy (47 out of 97), lumpectomy to bilateral lumpectomy (15 out of 97), and other (12 out of 97). Mostly, these management changes were because magnetic resonance imaging showed more extensive disease (n=29), additional cancer foci (n=39), or contralateral disease (n=24). In five instances, upgrading was due to patient preference. In 34% (50 out of 147) of the patients, there was no change in the planned operation. Regarding 97 of the patients having altered management, in 12 the changes were considered inappropriately extensive (due to false-positive magnetic resonance imaging findings). In terms of magnetic resonance imaging detection of more extensive, multifocal, multicentric, or contralateral disease, the false-positive rate was 13% and false-negative rate 7%. Corresponding rates for sensitivity and specificity were 95% and 81%, using the final pathology as the gold standard. Preoperative magnetic resonance imaging had a clinically significant and mostly correct impact on management plans. Magnetic resonance

Gadolinium-enhanced magnetic resonance imaging in acute myocardial infarction

International Nuclear Information System (INIS)

Dijkman, P.R.M. van; Wall, E.E. van der; Roos, A. de; Doornbos, J.; Laarse, A. van der; Voorthuisen, A.E. van; Bruschke, A.V.G.; Rossum, A.C. van

1990-01-01

To evaluate he usefulness of the paramagnetic contrast agent Gadolinium-DTPA (diethylenetriaminepentaacetic acid) in Magnetic Resonance. Imaging of acute myocardial infarction, we studied a total of 45 patients with a first acute myocardial infarction by ECG-gated magnetic resonance imaging before and after intravenous administration of 0.1 mmol/kg Gadolinium-DTPA. All patients received thrombolytic treatment by intravenous streptokinase. The magnetic resonance imaging studies were preformed after a meam of 88 h (range 15-241) after the acute onset of acute myocardial infarction. Five patients without evidence of cardiac disease served as controls. Spin-echo measurements (TE 30 ms) were made using a Philips Gyroscan (0.5 Tesla) or a Teslacon II (0.6 Tesla). The 45 patients were divided into four groups of patients. In Group I( patients) Gadolinium-DTPA improved the detection of myocardial infarction by Gadolinium-DTPA. In Group II (20 patients) the magnetic resonance imaging procedure was repeated every 10 min for up to 40 min following administration of Gadolinium-DTPA. Optimal contrast enhancement was obtained 20-25 min after Gadolinium-DTPA. In Group III (27 patients) signal intensities were significantly higher in the patients who underwent the magnetic resonance imaging study more than 72 h (mean 120) after the acute event, suggesting increased acculumation of Gadolinium-DTPA in a more advanced stage of the infarction process. In Group IV (45 patients) Gadolinium-DTPA was administered in an attempt to distinguish between reperfused and nonreperfused myocardial areas after thrombolytic treatment for acute myocardial infarction. The signal intensities did not differ, but reperfused areas showed a more homogeneous aspect whereas nonreperfused areas were visualized as a more heterogeneous contrast enhancement. It is concluded that magnetic resonance imaging using the contrast agent Gadolinium-DTPA significantly improves the detection of infarcted myocardial areas

Advances in cardiac magnetic resonance imaging of congenital heart disease

Energy Technology Data Exchange (ETDEWEB)

Driessen, Mieke M.P. [University of Utrecht, University Medical Center Utrecht, Department of Radiology, PO Box 85500, Utrecht (Netherlands); University of Utrecht, University Medical Center Utrecht, Department of Cardiology, PO Box 85500, Utrecht (Netherlands); The Interuniversity Cardiology Institute of the Netherlands (ICIN) - Netherlands Heart Institute, PO Box 19258, Utrecht (Netherlands); Breur, Johannes M.P.J. [Wilhelmina Children' s Hospital, University Medical Center Utrecht, Department of Pediatric Cardiology, PO Box 85500, Utrecht (Netherlands); Budde, Ricardo P.J.; Oorschot, Joep W.M. van; Leiner, Tim [University of Utrecht, University Medical Center Utrecht, Department of Radiology, PO Box 85500, Utrecht (Netherlands); Kimmenade, Roland R.J. van; Sieswerda, Gertjan Tj [University of Utrecht, University Medical Center Utrecht, Department of Cardiology, PO Box 85500, Utrecht (Netherlands); Meijboom, Folkert J. [University of Utrecht, University Medical Center Utrecht, Department of Cardiology, PO Box 85500, Utrecht (Netherlands); Wilhelmina Children' s Hospital, University Medical Center Utrecht, Department of Pediatric Cardiology, PO Box 85500, Utrecht (Netherlands)

2015-01-01

Due to advances in cardiac surgery, survival of patients with congenital heart disease has increased considerably during the past decades. Many of these patients require repeated cardiovascular magnetic resonance imaging to assess cardiac anatomy and function. In the past decade, technological advances have enabled faster and more robust cardiovascular magnetic resonance with improved image quality and spatial as well as temporal resolution. This review aims to provide an overview of advances in cardiovascular magnetic resonance hardware and acquisition techniques relevant to both pediatric and adult patients with congenital heart disease and discusses the techniques used to assess function, anatomy, flow and tissue characterization. (orig.)

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

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

Magnetic resonance imaging of the elbow. Part II: Abnormalities of the ligaments, tendons, and nerves

Energy Technology Data Exchange (ETDEWEB)

Kijowski, Richard; Tuite, Michael; Sanford, Matthew [University of Wisconsin Hospital, Department of Radiology, Madison, WI (United States)

2005-01-01

Part II of this comprehensive review on magnetic resonance imaging of the elbow discusses the role of magnetic resonance imaging in evaluating patients with abnormalities of the ligaments, tendons, and nerves of the elbow. Magnetic resonance imaging can yield high-quality multiplanar images which are useful in evaluating the soft tissue structures of the elbow. Magnetic resonance imaging can detect tears of the ulnar collateral ligament and lateral collateral ligament of the elbow with high sensitivity and specificity. Magnetic resonance imaging can determine the extent of tendon pathology in patients with medial epicondylitis and lateral epicondylitis. Magnetic resonance imaging can detect tears of the biceps tendon and triceps tendon and can distinguishing between partial and complete tendon rupture. Magnetic resonance imaging is also helpful in evaluating patients with nerve disorders at the elbow. (orig.)

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.)

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)

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).

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

Combined Conformal Strongly-Coupled Magnetic Resonance for Efficient Wireless Power Transfer

Directory of Open Access Journals (Sweden)

Matjaz Rozman

2017-04-01

Full Text Available This paper proposes a hybrid circuit between a conformal strongly-coupled magnetic resonance (CSCMR and a strongly-coupled magnetic resonance (SCMR, for better wireless power transmission (WPT. This combination promises to enhance the flexibility of the proposed four-loop WPT system. The maximum efficiency at various distances is achieved by combining coupling-matching between the source and transmitting coils along with the coupling factor between the transmitting and receiving coils. Furthermore, the distance between transmitting and receiving coils is investigated along with the distance relationship between the source loop and transmission coil, in order to achieve the maximum efficiency of the proposed hybrid WPT system. The results indicate that the proposed approach can be effectively employed at distances comparatively smaller than the maximum distance without frequency matching. The achievable efficiency can be as high as 84% for the whole working range of the transmitter. In addition, the proposed hybrid system allows more spatial freedom compared to existing chargers.

Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

Science.gov (United States)

Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

2014-01-21

A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

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

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.

Magnetic resonance imaging in the cranio-cervical region

International Nuclear Information System (INIS)

Koschorek, F.; Jensen, H.P.; Terwey, B.

1987-01-01

Since the introduction of nuclear magnetic resonance imaging (NMR) in the neurosurgical and neurological diagnostic this new imaging modality has shown to be of high diagnostic value - especially in disease process of the cranio-vertebral junction. Other imaging moralities such as x-ray CT and myelography are of inferior quality as the images are degraded by bone artifacts and superposition of other structures. NMR can reveal many aspects of the cranio-vertebral region in a single examination without artifacts from surrounding structures. A further improvement of NMR is the introduction of para-magnetic agents, such as gadolinium-DTPA, as it increases the specifity by dynamic magnetic resonance imaging. The authors present a review of their clinical experience

General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

Energy Technology Data Exchange (ETDEWEB)

Silenko, Alexander J. [Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation)

2017-05-15

A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantum-mechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. The main systematical errors are considered. (orig.)

Pre-clinical functional magnetic resonance imaging. Pt. I. The kidney

Energy Technology Data Exchange (ETDEWEB)

Zoellner, Frank G.; Kalayciyan, Raffi; Chacon-Caldera, Jorge; Zimmer, Fabian; Schad, Lothar R. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine

2014-07-01

The prevalence of chronic kidney disease (CKD) is increasing worldwide. In Europe alone, at least 8% of the population currently has some degree of CKD. CKD is associated with serious comorbidity, reduced life expectancy, and high economic costs; hence, the early detection and adequate treatment of kidney disease is important. Pre-clinical research can not only give insights into the mechanisms of the various kidney diseases but it also allows for investigating the outcome of new drugs developed to treat kidney disease. Functional magnetic resonance imaging provides non-invasive access to tissue and organ function in animal models. Advantages over classical animal research approaches are numerous: the same animal might be repeatedly imaged to investigate a progress or a treatment of disease over time. This has also a direct impact on animal welfare and the refinement of classical animal experiments as the number of animals in the studies might be reduced. In this paper, we review current state of the art in functional magnetic resonance imaging with a focus on pre-clinical kidney imaging.

Pre-clinical functional magnetic resonance imaging. Pt. I. The kidney

International Nuclear Information System (INIS)

Zoellner, Frank G.; Kalayciyan, Raffi; Chacon-Caldera, Jorge; Zimmer, Fabian; Schad, Lothar R.

2014-01-01

The prevalence of chronic kidney disease (CKD) is increasing worldwide. In Europe alone, at least 8% of the population currently has some degree of CKD. CKD is associated with serious comorbidity, reduced life expectancy, and high economic costs; hence, the early detection and adequate treatment of kidney disease is important. Pre-clinical research can not only give insights into the mechanisms of the various kidney diseases but it also allows for investigating the outcome of new drugs developed to treat kidney disease. Functional magnetic resonance imaging provides non-invasive access to tissue and organ function in animal models. Advantages over classical animal research approaches are numerous: the same animal might be repeatedly imaged to investigate a progress or a treatment of disease over time. This has also a direct impact on animal welfare and the refinement of classical animal experiments as the number of animals in the studies might be reduced. In this paper, we review current state of the art in functional magnetic resonance imaging with a focus on pre-clinical kidney imaging.

Electronic and transport properties of noncollinear magnetic monatomic Mn chains: Fano resonances in the superlattice of noncollinear magnetic barriers and magnetic anisotropic bands

International Nuclear Information System (INIS)

Dai, C.J.; Yan, X.H.; Xiao, Y.; Guo, Y.D.

2015-01-01

By means of the density functional theory combined with non-equilibrium Green's function method, ballistic transport properties of one-dimensional noncollinear magnetic monatomic chains were investigated using the single-atomic Mn chains as a model system. Fano resonances are found to exist in the monatomic Mn chains with spin-spiral structure. Furthermore, in the monatomic Mn chains with magnetic soliton lattice, Fano resonances are enhanced and cause the conductance splitting in the transmission spectra. The Fano resonances in the noncollinear magnetic single-atomic Mn chains are arising from the coupling of the localized d-states and the extended states of the quantum channels. By constructing a theoretical model and calculating its conductance, it is found that the phenomena of Fano resonances and the accompanying conductance splitting exist universally in the superlattice of one-dimensional noncollinear magnetic barriers, due to the interference of the incident waves and reflected waves by the interfaces between the neighboring barriers. Moreover, the band structures of the ferromagnetic and spin-spiral monatomic Mn chains exhibit a strong dependence on the spatial arrangement of the magnetic moments of Mn atoms when spin–orbit coupling is considered. - Highlights: • Transport properties of noncollinear magnetic monatomic Mn chains are studied. • Fano resonances are found in the noncollinear magnetic monatomic Mn chains. • Magnetic soliton lattice leads to conductance splitting in the transmission curve. • Fano resonances exist in the superlattice of noncollinear magnetic barriers. • Effect of SOC on the band structure of FM and spin-spiral Mn chains are studied

Optimization of saddle coils for magnetic resonance imaging

International Nuclear Information System (INIS)

Salmon, Carlos Ernesto Garrido; Vidoto, Edson Luiz Gea; Martins, Mateus Jose; Tannus, Alberto

2006-01-01

In Nuclear Magnetic Resonance (NMR) experiments, besides the apparatus designed to acquire the NMR signal, it is necessary to generate a radio frequency electromagnetic field using a device capable to transduce electromagnetic power into a transverse magnetic field. We must generate this transverse homogeneous magnetic field inside the region of interest with minimum power consumption. Many configurations have been proposed for this task, from coils to resonators. For low field intensity (<0.5 T) and small sample dimensions (<30 cm), the saddle coil configuration has been widely used. In this work we present a simplified method for calculating the magnetic field distribution in these coils considering the current density profile. We propose an optimized saddle configuration as a function of the dimensions of the region of interest, taking into account the uniformity and the sensitivity. In order to evaluate the magnetic field uniformity three quantities have been analyzed: Non-uniformity, peak-to-peak homogeneity and relative uniformity. Some experimental results are presented to validate our calculation. (author)

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)

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.

Resonant tunnel magnetoresistance in double-barrier planar magnetic tunnel junctions

KAUST Repository

Useinov, A. N.

2011-08-24

We present a theoretical approach to calculate the spin-dependent current and tunnel magnetoresistance (TMR) in a double-barrier magnetic tunnel junction (DMTJ), in which the magnetization of the middle ferromagnetic metal layer can be aligned parallel or antiparallel in relation to the fixed magnetizations of the left and right ferromagnetic electrodes. The electron transport through the DMTJ is considered as a three-dimensional problem, taking into account all transmitting electron trajectories as well as the spin-dependent momentum conservation law. The dependence of the transmission coefficient and spin-polarized currents on the applied voltage is derived as an exact solution to the quantum-mechanical problem for the spin-polarized transport. In the range of the developed physical model, the resonant tunneling, nonresonant tunneling, and enhanced spin filtering can be explained; the simulation results are in good agreement with experimental data.

Resonant tunnel magnetoresistance in double-barrier planar magnetic tunnel junctions

KAUST Repository

Useinov, A. N.; Kosel, Jü rgen; Useinov, N. Kh.; Tagirov, L. R.

2011-01-01

We present a theoretical approach to calculate the spin-dependent current and tunnel magnetoresistance (TMR) in a double-barrier magnetic tunnel junction (DMTJ), in which the magnetization of the middle ferromagnetic metal layer can be aligned parallel or antiparallel in relation to the fixed magnetizations of the left and right ferromagnetic electrodes. The electron transport through the DMTJ is considered as a three-dimensional problem, taking into account all transmitting electron trajectories as well as the spin-dependent momentum conservation law. The dependence of the transmission coefficient and spin-polarized currents on the applied voltage is derived as an exact solution to the quantum-mechanical problem for the spin-polarized transport. In the range of the developed physical model, the resonant tunneling, nonresonant tunneling, and enhanced spin filtering can be explained; the simulation results are in good agreement with experimental data.

Magnetic resonance and the diagnosis of short stature of hypothalamic-hypophyseal origin

International Nuclear Information System (INIS)

Vannelli, S.; Avataneo, T.; Benso, L.; Potenzoni, F.; Cirillo, S.; Mostert, M.; Bona, G.

1993-01-01

Magnetic resonance imaging was performed in 23 patients with short stature (7 had multiple pituitary hormone defect, 11 had isolated growth hormone deficiency and 5 had normal variant short stature) to investigate if there is a relation between magnetic resonance findings and results of endocrine tests. Magnetic resonance imaging of patients with multiple pituitary hormone deficiency or with serious isolated growth hormone deficiency (growth hormone 3μg/l) or with normal variant short stature, the technique revealed a normal or hypoplastic hypophysis. Magnetic resonance appears to be a useful second-level diagnostic tool in defining the type of alteration in growth defects of endocrine origin. 26 refs., 5 figs., 2 tabs

Nitroxide radicals as contrast substances for magnetic resonance imaging diagnostics. Part 1

International Nuclear Information System (INIS)

Zhelev, Z.

2016-01-01

In last ten years, there is a significant progress in the selective and localized detection of redox-active compounds in the cells, tissues, and intact organisms. This progress is due to the development of new synthetic and genetically encoded redox-sensitive contrast substances, as well as due to the improvement of the techniques for their imaging: fluorescent, chemiluminescent, magnetic resonance, nuclear, ultrasonic. One of the most attractive redox-sensitive contrast substances are cyclic (stable) nitroxide radicals. They can be visualized and analyzed in vitro and in vivo by a variety of magnetic resonance techniques - electron-paramagnetic resonance imaging (EPRI), magnetic resonance imaging (MRI), Overhauser-enhanced MRI (OMRI). This review describes the merits and demerits of the nitroxide-enhanced EPR and MRI and the perspectives for their application in biomedical studies and clinical practice. The article is intended for a wide range of readers - from students to specialists in the field. Key words: Magnetic Resonance Imaging (MRI). Electron-Paramagnetic Resonance (EPR). Overhauser-Enhanced MRI (O MRI). Nitroxide

Bony vibration stimulation test combined with magnetic resonance imaging. Can discography be replaced?

Science.gov (United States)

Yrjämä, M; Tervonen, O; Kurunlahti, M; Vanharanta, H

1997-04-01

The results of two noninvasive methods, magnetic resonance imaging and a bony vibration test, were compared with discographic pain provocation findings. To evaluate whether the combination of magnetic resonance imaging and vibration pain provocation tests could be used to replace discography in low back pain diagnostics. Magnetic resonance imaging gives a wealth of visual information on anatomic changes of the spine with often unknown clinical significance. Discographic examination of the spine is still the only widely accepted diagnostic method that can relate the pathoanatomic changes to the patient's clinical pain. Internal anular rupture has been shown to be one of the sources of back pain. The bony vibration test of the spinal processes has been shown correlate well with discographic pain provocation tests in cases of internal anular rupture. The three lowest lumbar discs of 33 patients with back pain were examined by means of magnetic resonance imaging and a bony vibration stimulation test, and the results were compared with those from computed tomography-discography. In cases of intradiscal magnetic resonance imaging findings, the vibration provocation test showed a sensitivity of 0.88 and a specificity of 0.50 compared with the discographic pain provocation test. If the patients with previous back surgery were excluded, the specificity was 0.75. In the cases of total anular rupture, the sensitivity was 0.50, and the specificity was 0.33. The combination of the two noninvasive methods, vibration stimulation and magnetic resonance imaging, gives more information on the origin of the back pain than magnetic resonance imaging alone. The pathoanatomic changes seen in magnetic resonance imaging can be correlated with the patient's disorder more reliably using the vibration provocation test in the cases of partial anular ruptures. The use of discography can be limited mostly to cases with total anular ruptures detected by magnetic resonance imaging.

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.

Dextran-coated superparamagnetic amorphous Fe–Co nanoalloy for magnetic resonance imaging applications

International Nuclear Information System (INIS)

An, Lu; Yu, Yanrong; Li, Xuejian; Liu, Wei; Yang, Hong; Wu, Dongmei; Yang, Shiping

2014-01-01

Graphical abstract: A dextran-coated Fe–Co nanoalloy was developed serving as a sensitive contrast agent for magnetic resonance imaging applications. - Highlights: • Amorphous Fe–Co nanoalloy was prepared via wet chemical reduction approach. • The Fe–Co nanoalloy is water-soluble, stable, and biocompatible. • The Fe–Co nanoalloy is superparamagnetic. • The Fe–Co nanoalloy exhibits T 2 -weighted MR enhancement both in vitro and in vivo. - Abstract: For magnetic resonance imaging applications, a facile approach for water-soluble dextran coated amorphous Fe–Co nanoalloy was developed. The as-synthesized nanoalloy had a diameter of 9 nm with a narrow size distribution and showed superparamagnetic property with a saturated magnetization (Ms) of 25 emu/g. In vitro cytotoxicity test revealed that it was biocompatible at a concentration below 120 μg/mL. It can be uptaken by HeLa cells effectively and resulted in the obvious T 2 effect after internalization. Biodistribution studies in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) confirmed that Fe–Co nanoalloy was preferentially accumulated in lung and spleen after intravenous injection for 4 h. In vivo MRI, dextran-coated Fe–Co nanoalloy can serve as a sensitive contrast agent for MR imaging, especially in the spleen, so we believe that it maybe hold great promise for diagnosis of splenic disease by appropriately functionalizing their surface

Dextran-coated superparamagnetic amorphous Fe–Co nanoalloy for magnetic resonance imaging applications

Energy Technology Data Exchange (ETDEWEB)

An, Lu; Yu, Yanrong; Li, Xuejian; Liu, Wei [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Yang, Hong, E-mail: yanghong@shnu.edu.cn [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Wu, Dongmei [Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Yang, Shiping, E-mail: shipingy@shnu.edu.cn [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China)

2014-01-01

Graphical abstract: A dextran-coated Fe–Co nanoalloy was developed serving as a sensitive contrast agent for magnetic resonance imaging applications. - Highlights: • Amorphous Fe–Co nanoalloy was prepared via wet chemical reduction approach. • The Fe–Co nanoalloy is water-soluble, stable, and biocompatible. • The Fe–Co nanoalloy is superparamagnetic. • The Fe–Co nanoalloy exhibits T{sub 2}-weighted MR enhancement both in vitro and in vivo. - Abstract: For magnetic resonance imaging applications, a facile approach for water-soluble dextran coated amorphous Fe–Co nanoalloy was developed. The as-synthesized nanoalloy had a diameter of 9 nm with a narrow size distribution and showed superparamagnetic property with a saturated magnetization (Ms) of 25 emu/g. In vitro cytotoxicity test revealed that it was biocompatible at a concentration below 120 μg/mL. It can be uptaken by HeLa cells effectively and resulted in the obvious T{sub 2} effect after internalization. Biodistribution studies in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) confirmed that Fe–Co nanoalloy was preferentially accumulated in lung and spleen after intravenous injection for 4 h. In vivo MRI, dextran-coated Fe–Co nanoalloy can serve as a sensitive contrast agent for MR imaging, especially in the spleen, so we believe that it maybe hold great promise for diagnosis of splenic disease by appropriately functionalizing their surface.

Approximate fuzzy C-means (AFCM) cluster analysis of medical magnetic resonance image (MRI) data

International Nuclear Information System (INIS)

DelaPaz, R.L.; Chang, P.J.; Bernstein, R.; Dave, J.V.

1987-01-01

The authors describe the application of an approximate fuzzy C-means (AFCM) clustering algorithm as a data dimension reduction approach to medical magnetic resonance images (MRI). Image data consisted of one T1-weighted, two T2-weighted, and one T2*-weighted (magnetic susceptibility) image for each cranial study and a matrix of 10 images generated from 10 combinations of TE and TR for each body lymphoma study. All images were obtained with a 1.5 Tesla imaging system (GE Signa). Analyses were performed on over 100 MR image sets with a variety of pathologies. The cluster analysis was operated in an unsupervised mode and computational overhead was minimized by utilizing a table look-up approach without adversely affecting accuracy. Image data were first segmented into 2 coarse clusters, each of which was then subdivided into 16 fine clusters. The final tissue classifications were presented as color-coded anatomically-mapped images and as two and three dimensional displays of cluster center data in selected feature space (minimum spanning tree). Fuzzy cluster analysis appears to be a clinically useful dimension reduction technique which results in improved diagnostic specificity of medical magnetic resonance images

Electromagnetically induced transparency resonances inverted in magnetic field

Energy Technology Data Exchange (ETDEWEB)

Sargsyan, A.; Sarkisyan, D., E-mail: davsark@yahoo.com, E-mail: david@ipr.sci.am [National Academy of Sciences of Armenia, Institute for Physical Research (Armenia); Pashayan-Leroy, Y.; Leroy, C. [Université de Bourgogne-Dijon, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS (France); Cartaleva, S. [Bulgarian Academy of Sciences, Institute of Electronics (Bulgaria); Wilson-Gordon, A. D. [Bar-Ilan University Ramat Gan, Department of Chemistry (Israel); Auzinsh, M. [University of Latvia, Department of Physics (Latvia)

2015-12-15

The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the {sup 87}Rb D{sub 1} line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ{sub rel} are used: an Rb cell with antirelaxation coating (L ∼ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.

Force-detected nuclear magnetic resonance: recent advances and future challenges.

Science.gov (United States)

Poggio, M; Degen, C L

2010-08-27

We review recent efforts to detect small numbers of nuclear spins using magnetic resonance force microscopy. Magnetic resonance force microscopy (MRFM) is a scanning probe technique that relies on the mechanical measurement of the weak magnetic force between a microscopic magnet and the magnetic moments in a sample. Spurred by the recent progress in fabricating ultrasensitive force detectors, MRFM has rapidly improved its capability over the last decade. Today it boasts a spin sensitivity that surpasses conventional, inductive nuclear magnetic resonance detectors by about eight orders of magnitude. In this review we touch on the origins of this technique and focus on its recent application to nanoscale nuclear spin ensembles, in particular on the imaging of nanoscale objects with a three-dimensional (3D) spatial resolution better than 10 nm. We consider the experimental advances driving this work and highlight the underlying physical principles and limitations of the method. Finally, we discuss the challenges that must be met in order to advance the technique towards single nuclear spin sensitivity-and perhaps-to 3D microscopy of molecules with atomic resolution.

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

Small-scale instrumentation for nuclear magnetic resonance of porous media

International Nuclear Information System (INIS)

Bluemich, Bernhard; Casanova, Federico; Dabrowski, Martin; Danieli, Ernesto; Haber, Agnes; Van Landeghem, Maxime; Haber-Pohlmeier, Sabina; Olaru, Alexandra; Perlo, Juan; Sucre, Oscar; Evertz, Loribeth

2011-01-01

The investigation of fluids confined to porous media is the oldest topic of investigation with small-scale nuclear magnetic resonance (NMR) instruments, as such instruments are mobile and can be moved to the site of the object, such as the borehole of an oil well. While the analysis was originally restricted by the inferior homogeneity of the employed magnets to relaxation measurements, today, portable magnets are available for all types of NMR measurements concerning relaxometry, imaging and spectroscopy in two types of geometries. These geometries refer to closed magnets that surround the sample and open magnets, which are brought close to the object for measurement. The current state of the art of portable, small-scale NMR instruments is reviewed and recent applications of such instruments are featured. These include the porosity analysis and description of diesel particulate filters, the determination of the moisture content in walls from gray concrete, new approaches to analyze the pore space and moisture migration in soil, and the constitutional analysis of the mortar base of ancient wall paintings.

Comparison of nuclear electric resonance and nuclear magnetic resonance in integer and fractional quantum Hall states

International Nuclear Information System (INIS)

Tomimatsu, Toru; Shirai, Shota; Hashimoto, Katsushi; Sato, Ken; Hirayama, Yoshiro

2015-01-01

Electric-field-induced nuclear resonance (NER: nuclear electric resonance) involving quantum Hall states (QHSs) was studied at various filling factors by exploiting changes in nuclear spins polarized at quantum Hall breakdown. Distinct from the magnetic dipole interaction in nuclear magnetic resonance, the interaction of the electric-field gradient with the electric quadrupole moment plays the dominant role in the NER mechanism. The magnitude of the NER signal strongly depends on whether electronic states are localized or extended. This indicates that NER is sensitive to the screening capability of the electric field associated with QHSs

Magnetic resonance of semiconductors and their nanostructures basic and advanced applications

CERN Document Server

Baranov, Pavel G; Jelezko, Fedor; Wrachtrup, Jörg

2017-01-01

This book explains different magnetic resonance (MR) techniques and uses different combinations of these techniques to analyze defects in semiconductors and nanostructures. It also introduces novelties such as single defects MR and electron-paramagnetic-resonance-based methods: electron spin echo, electrically detected magnetic resonance, optically detected magnetic resonance and electron-nuclear double resonance – the designated tools for investigating the structural and spin properties of condensed systems, living matter, nanostructures and nanobiotechnology objects. Further, the authors address problems existing in semiconductor and nanotechnology sciences that can be resolved using MR, and discuss past, current and future applications of MR, with a focus on advances in MR methods. The book is intended for researchers in MR studies of semiconductors and nanostructures wanting a comprehensive review of what has been done in their own and related fields of study, as well as future perspectives.

Diffusion and Perfusion Magnetic Resonance Imaging:Fundamentals and Advances

OpenAIRE

Assili, Sanam

2016-01-01

Over the past few decades, magnetic resonance imaging has been utilized as a powerful imaging modality to evaluate the structure and function of various organs in the human body,such as the brain. Additionally, diffusion and perfusion MR imaging have been increasingly used in neurovascular clinical applications. In diffusion-weighted magnetic resonance imaging, the mobility of water molecules is explored in order to obtain information about the microscopic behavior of the tissues. In contrast...

Magnetic Resonance Elastography and Other Magnetic Resonance Imaging Techniques in Chronic Liver Disease: Current Status and Future Directions

Science.gov (United States)

Tan, Cher Heng; Venkatesh, Sudhakar Kundapur

2016-01-01

Recent advances in the noninvasive imaging of chronic liver disease have led to improvements in diagnosis, particularly with magnetic resonance imaging (MRI). A comprehensive evaluation of the liver may be performed with the quantification of the degree of hepatic steatosis, liver iron concentration, and liver fibrosis. In addition, MRI of the liver may be used to identify complications of cirrhosis, including portal hypertension, ascites, and the development of hepatocellular carcinoma. In this review article, we discuss the state of the art techniques in liver MRI, namely, magnetic resonance elastography, hepatobiliary phase MRI, and liver fat and iron quantification MRI. The use of these advanced techniques in the management of chronic liver diseases, including non-alcoholic fatty liver disease, will be elaborated. PMID:27563019

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

Ultra-fast magnetic resonance encephalography of physiological brain activity - Glymphatic pulsation mechanisms?

Science.gov (United States)

Kiviniemi, Vesa; Wang, Xindi; Korhonen, Vesa; Keinänen, Tuija; Tuovinen, Timo; Autio, Joonas; LeVan, Pierre; Keilholz, Shella; Zang, Yu-Feng; Hennig, Jürgen; Nedergaard, Maiken

2016-06-01

The theory on the glymphatic convection mechanism of cerebrospinal fluid holds that cardiac pulsations in part pump cerebrospinal fluid from the peri-arterial spaces through the extracellular tissue into the peri-venous spaces facilitated by aquaporin water channels. Since cardiac pulses cannot be the sole mechanism of glymphatic propulsion, we searched for additional cerebrospinal fluid pulsations in the human brain with ultra-fast magnetic resonance encephalography. We detected three types of physiological mechanisms affecting cerebral cerebrospinal fluid pulsations: cardiac, respiratory, and very low frequency pulsations. The cardiac pulsations induce a negative magnetic resonance encephalography signal change in peri-arterial regions that extends centrifugally and covers the brain in ≈1 Hz cycles. The respiratory ≈0.3 Hz pulsations are centripetal periodical pulses that occur dominantly in peri-venous areas. The third type of pulsation was very low frequency (VLF 0.001-0.023 Hz) and low frequency (LF 0.023-0.73 Hz) waves that both propagate with unique spatiotemporal patterns. Our findings using critically sampled magnetic resonance encephalography open a new view into cerebral fluid dynamics. Since glymphatic system failure may precede protein accumulations in diseases such as Alzheimer's dementia, this methodological advance offers a novel approach to image brain fluid dynamics that potentially can enable early detection and intervention in neurodegenerative diseases. © The Author(s) 2015.

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

Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

Energy Technology Data Exchange (ETDEWEB)

Li, Hai-ming; Liu, Shao-bin, E-mail: lsb@nuaa.edu.cn; Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun [Key Laboratory of Radar Imaging and Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Shen-yun [Research Center of Applied Electromagnetics, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2015-03-16

In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

A Magnetic Resonance Imaging Receiver Design Based on NI PXIe-7966R

Directory of Open Access Journals (Sweden)

HU Jin-jie

2017-12-01

Full Text Available A magnetic resonance imaging receiver design based on NI PXIe-7966R is proposed, with which the magnetic resonance signals are sampled directly and down-converted digitally, the raw data are uploaded and the magnetic resonance image are restored. The system-level digital signal processing (DSP development tools offered by NI LabVIEW field programmable gate array (FPGA was used for FPGA function modeling, simulation and automatic code generation of hardware description language (HDL. It was very flexible during the digital down conversion (DDC designing. The sampling rate of this module was 50 Mbps, and the receiver bandwidth could be varied between 100 Hz and 1 MHz. The experimental results showed that the receiver design is a high performance magnetic resonance receiver solution.

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...

Assessment of coronary artery disease with nicorandil stress magnetic resonance imaging

International Nuclear Information System (INIS)

Kawase, Yoshio; Nichimoto, Masaki; Hato, Katsunori; Okajima, Kazue; Yoshikawa, Junichi

2004-01-01

Although dipyridamole and adenosine have been used as vasodilator agents, we believe they are inadequate for vasodilator perfusion magnetic resonance imaging, due to adverse effects (flushing, warmth, headaches, and arrhythmia). Nicorandil, a potassium channel opener, has been reported to increase coronary blood flow and it was associated with fewer adverse effects than adenosine or dipiridamole. We set out to investigate whether the coronary artery stenosis could be assessed by nicorandil stress perfusion magnetic resonance imaging. First-pass contrast-enhanced magnetic resonance images of the left ventricle acquired from 50 patients at rest and during intravenous administration of nicorandil using multi-slice turbo field echo with multi shot echo-planar-imaging. Coronary angiography was performed within 1 week. There was no adverse effects during nicorandil stress in any patients. The overall sensitivity and specificity of magnetic resonance imaging in identifying patients with significant stenosis of at least one coronary artery were 93.9% (31 of 33 patients) and 94.1% (16 of 17 patients), respectively. The sensitivity of magnetic resonance imaging for detecting significant stenosis in the left anterior descending artery was 87.5%; the sensitivity in the left circumflex artery was 80%; the sensitivity in the right coronary artery was 92.3%. Similar sensitivities were observed for all 3 vascular regions, indicating that all myocardial segments were visualized with similar image quality. The present study shows that nicorandil stress perfusion magnetic resonance imaging is a safe, feasible technique for assessing coronary artery stenosis severity in a totally-noninvasive manner. (authors)

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

Electron-nuclear magnetic resonance in the inverted state

International Nuclear Information System (INIS)

Ignatchenko, V.A.; Tsifrinovich, V.I.

1975-01-01

The paper considers the susceptibility of the electron-nucleus system of a ferromagnet when nuclear magnetization is inverted with respect to the hyperfine field direction. The inverted state is a situation in which nuclear magnetization is turned through π relative to its equilibrium orientation, whereas electron magnetization is in an equilibrium state with respect to an external magnetic field. The consideration is carried out for a thin plate magnetized in its plane. Amplification of a weak radiofrequency signal can be attained under the fulfilment of an additional inequality relating the interaction frequency with electron and nuclear relaxation parameters. The gain may exceed the gain for an inverted nuclear system in magnetically disordered substances. In the range of strong interaction between the frequencies of ferromagnetic (FMR) and nuclear magnetic (NMR) resonances the electron-nuclear magnetic resonance (ENMR) spectrum possesses a fine structure which is inverse to that obtained for the ENMR spectrum in a normal state. The inverted state ENMR line shape is analysed in detail for the case of so weak HF fields that the relaxation conditions may be regarded as stationary. The initial (linear) stages of a forced transient process arising in an electron-nuclear system under the effect of a strong HF field are briefly analysed

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

Energy Technology Data Exchange (ETDEWEB)

Mishra, S.; Gammon, W.J.; Pappas, D.P. [Virginia Commonwealth Univ., Richmond, VA (United States)] [and others

1997-04-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield.

Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

International Nuclear Information System (INIS)

Mishra, S.; Gammon, W.J.; Pappas, D.P.

1997-01-01

The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield

Ultra-Wideband Sensors for Improved Magnetic Resonance Imaging, Cardiovascular Monitoring and Tumour Diagnostics

Directory of Open Access Journals (Sweden)

Frank Seifert

2010-12-01

Full Text Available The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour’s contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied.

Ultra-wideband sensors for improved magnetic resonance imaging, cardiovascular monitoring and tumour diagnostics.

Science.gov (United States)

Thiel, Florian; Kosch, Olaf; Seifert, Frank

2010-01-01

The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour's contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied.

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.

Magnetism in heterogeneous thin film systems: Resonant X-ray scattering studies

International Nuclear Information System (INIS)

Kortright, J.B.; Jiang, J.S.; Bader, S.D.; Hellwig, O.; Marguiles, D.T.; Fullerton, E.E.

2002-01-01

Magnetic and chemical heterogeneity are common in a broad range of magnetic thin film systems. Emerging resonant soft x-ray scattering techniques are well suited to resolve such heterogeneity at relevant length scales. Resonant x-ray magneto-optical Kerr effect measurements laterally average over heterogeneity but can provide depth resolution in different ways, as illustrated in measurements resolving reversible and irreversible changes in different layers of exchange-spring heterostructures. Resonant small-angle scattering measures in-plane heterogeneity and can resolve magnetic and chemical scattering sources in different ways, as illustrated in measurements of granular alloy recording media

Magnetic resonance imaging of the shoulder

International Nuclear Information System (INIS)

Ilieva, E.

2015-01-01

Full text: Magnetic resonance imaging (MRI) is an excellent non-invasive imaging tool that can complement the physical examination in the evaluation of traumatic and non-traumatic injuries of the shoulder. The superb soft tissue contrast and multiplanar capabilities of MRI make it a preferred modality to provide a global assessment of the soft tissue and osseous structures of the shoulder. Learning objectives: to review briefly the anatomy of the shoulder and the specificity of sequences and planes for MRI; to demonstrate the characteristic MR findings of some of the most common shoulder disorders; to indicate how MR arthrography (MRA) of the shoulder can add extra value to the diagnostic process; to outline a systematic approach to the interpretation of the shoulder MR examination. Choosing the most suitable sequences and planes as well as the thorough knowledge of the anatomic structures assist the correct diagnosis of the pathologic disorders of the shoulder which is of great importance for the precise treatment management, surgical versus conservative, as well as for the appropriate surgical approach, open versus arthroscopic

Migraine and magnetic resonance spectroscopy

DEFF Research Database (Denmark)