Science.gov

Sample records for 1999-04 tesla fel-report

  1. Edison vs. Tesla

    ScienceCinema

    Hogan, Kathleen; Wallace, Hal; Ivestor, Rob

    2016-07-12

    As Edison vs. Tesla week heats up at the Energy Department, we are exploring the rivalry between Thomas Edison and Nikola Tesla and how their work is still impacting the way we use energy today. Whether you're on Team Tesla or Team Edison, both inventors were key players in creating things like batteries, power plants and wireless technologies -- all innovations we still use today. And as we move toward a clean energy future, energy efficient lighting, like LED bulbs, and more efficient electric motors not only help us save money on electricity costs but help combat climate change. For this, Tesla and Edison both deserve our recognition.

  2. Edison vs. Tesla

    SciTech Connect

    Hogan, Kathleen; Wallace, Hal; Ivestor, Rob

    2013-11-20

    As Edison vs. Tesla week heats up at the Energy Department, we are exploring the rivalry between Thomas Edison and Nikola Tesla and how their work is still impacting the way we use energy today. Whether you're on Team Tesla or Team Edison, both inventors were key players in creating things like batteries, power plants and wireless technologies -- all innovations we still use today. And as we move toward a clean energy future, energy efficient lighting, like LED bulbs, and more efficient electric motors not only help us save money on electricity costs but help combat climate change. For this, Tesla and Edison both deserve our recognition.

  3. The TESLA RF System

    NASA Astrophysics Data System (ADS)

    Choroba, S.

    2003-12-01

    The TESLA project proposed by the TESLA collaboration in 2001 is a 500 to 800GeV e+/e- linear collider with integrated free electron laser facility. The accelerator is based on superconducting cavity technology. Approximately 20000 superconducting cavities operated at 1.3GHz with a gradient of 23.4MV/m or 35MV/m will be required to achieve the energy of 500GeV or 800GeV respectively. For 500GeV ˜600 RF stations each generating 10MW of RF power at 1.3GHz at a pulse duration of 1.37ms and a repetition rate of 5 or 10Hz are required. The original TESLA design was modified in 2002 and now includes a dedicated 20GeV electron accelerator in a separate tunnel for free electron laser application. The TESLA XFEL will provide XFEL radiation of unprecedented peak brilliance and full transverse coherence in the wavelength range of 0.1 to 6.4nm at a pulse duration of 100fs. The technology of both accelerators, the TESLA linear collider and the XFEL, will be identical, however the number of superconducting cavities and RF stations for the XFEL will be reduced to 936 and 26 respectively. This paper describes the layout of the entire RF system of the TESLA linear collider and the TESLA XFEL and gives an overview of its various subsystems and components.

  4. Science at 100 Tesla

    NASA Astrophysics Data System (ADS)

    Harrison, Neil

    2012-10-01

    Within the last year, Los Alamos National Labs produced magnetic fields of 100 tesla strength non-destructively for the first time. Fields of such a strength open up many new possibilities for condensed matter research. I will present some recent examples of condensed matter physics experiments performed in magnetic fields reaching 100 tesla, which includes recent work on high temperature superconductivity, magnetism and low dimensional materials.

  5. Photon collider at TESLA

    NASA Astrophysics Data System (ADS)

    Telnov, Valery

    2001-10-01

    High energy photon colliders ( γγ, γe) based on backward Compton scattering of laser light is a very natural addition to e +e - linear colliders. In this report, we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case, the γγ luminosity in the high energy part of spectrum can reach about (1/3) Le +e -. Typical cross-sections of interesting processes in γγ collisions are higher than those in e +e - collisions by about one order of magnitude, so the number of events in γγ collisions will be more than that in e +e - collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is "an optical storage ring (optical trap)" with a diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based on the linear collider TESLA, its possible parameters and existing problems.

  6. Note: Tesla transformer damping

    NASA Astrophysics Data System (ADS)

    Reed, J. L.

    2012-07-01

    Unexpected heavy damping in the two winding Tesla pulse transformer is shown to be due to small primary inductances. A small primary inductance is a necessary condition of operability, but is also a refractory inefficiency. A 30% performance loss is demonstrated using a typical "spiral strip" transformer. The loss is investigated by examining damping terms added to the transformer's governing equations. A significant alteration of the transformer's architecture is suggested to mitigate these losses. Experimental and simulated data comparing the 2 and 3 winding transformers are cited to support the suggestion.

  7. TESLA & ILC Cryomodules

    SciTech Connect

    Peterson, T. J.; Weisend, II, J. G.

    2016-01-01

    The TESLA collaboration developed a unique variant of SRF cryomodule designs, the chief feature being use of the large, low pressure helium vapor return pipe as the structural support backbone of the cryomodule. Additional innovative features include all cryogenic piping within the cryomodule (no parallel external cryogenic transfer line), long strings of RF cavities within a single cryomodule, and cryomodules connected in series. Several projects, including FLASH and XFEL at DESY, LCLS-II at SLAC, and the ILC technical design have adopted this general design concept. Advantages include saving space by eliminating the external transfer line, relatively tight packing of RF cavities along the beamline due to fewer warm-cold transitions, and potentially lower costs. However, a primary disadvantage is the relative lack of independence for warm-up, replacement, and cool-down of individual cryomodules.

  8. [70 years of Nikola Tesla studies].

    PubMed

    Juznic, Stanislav

    2013-01-01

    Nikola Tesla's studies of chemistry are described including his not very scholarly affair in Maribor. After almost a century and half of hypothesis at least usable scenario of Tesla's life and "work" in Maribor is provided. The chemistry achievements of Tesla's most influential professors Martin Sekulić and Tesla's Graz professors are put into the limelight. The fact that Tesla in Graz studied on the technological chemistry Faculty of Polytechnic is focused.

  9. [70 years of Nikola Tesla studies].

    PubMed

    Juznic, Stanislav

    2013-01-01

    Nikola Tesla's studies of chemistry are described including his not very scholarly affair in Maribor. After almost a century and half of hypothesis at least usable scenario of Tesla's life and "work" in Maribor is provided. The chemistry achievements of Tesla's most influential professors Martin Sekulić and Tesla's Graz professors are put into the limelight. The fact that Tesla in Graz studied on the technological chemistry Faculty of Polytechnic is focused. PMID:23878954

  10. Nikola Tesla: the Moon's rotation.

    NASA Astrophysics Data System (ADS)

    Tomić, A.; Jovanović, B. S.

    1993-09-01

    The review of three articles by N. Tesla, published in the year 1919 in the journal "Electrical experimenter" is given, with special reference to the astronomical contents and to circumstances in which they appeared.

  11. [Nikola Tesla in medicine, too].

    PubMed

    Hanzek, Branko; Jakobović, Zvonimir

    2007-12-01

    Using primary and secondary sources we have shown in this paper the influence of Nikola Tesla's work on the field of medicine. The description of his experiments conduced within secondary-school education programs aimed to present the popularization of his work in Croatia. Although Tesla was dedicated primarily to physics and was not directly involved in biomedical research, his work significantly contributed to paving the way of medical physics particularly radiology and high-frequency electrotherapy.

  12. [Nikola Tesla in medicine, too].

    PubMed

    Hanzek, Branko; Jakobović, Zvonimir

    2007-12-01

    Using primary and secondary sources we have shown in this paper the influence of Nikola Tesla's work on the field of medicine. The description of his experiments conduced within secondary-school education programs aimed to present the popularization of his work in Croatia. Although Tesla was dedicated primarily to physics and was not directly involved in biomedical research, his work significantly contributed to paving the way of medical physics particularly radiology and high-frequency electrotherapy. PMID:18383745

  13. Tesla's First Footsteps into Chemical Sciences.

    PubMed

    Južnič, Stanislav

    2016-01-01

    For the first time a complete list of Tesla's High School professors is provided. The excellency of his lecturers of chemistry and related sciences is put into the limelight. The books and articles about chemistry which Tesla read in his High School times are focused together with the related published works of his teachers. The pioneering spectroscopic research of Kirchhoff and Bunsen began in Tesla's early youth and had a considerable impact on Tesla's professors, especially on Martin Sekulić. PMID:27640397

  14. The TESLA Free Electron Laser

    NASA Astrophysics Data System (ADS)

    Rossbach, Jörg

    1997-05-01

    The TESLA Free Electron Laser makes use of the high quality electron beam that can be provided by the superconducting TESLA linac to drive a single pass free electron laser (FEL) at wavelengths far below the visible. To reach a wavelength of 6 nanometers, the TESLA Test Facility (TTF) currently under construction at DESY will be extended to 1 GeV beam energy. Because there are no mirrors and seed-lasers in this wavelength regime, the principle of Self-Amplified-Spontaneous-Emission (SASE) will be employed. A first test of both the principle and technical components is foreseen at a photon wavelength larger than 42 nanometers. With respect to linac technology, the key prerequisite for such single-pass, high-gain FELs is a high intensity, diffraction limited, electron beam to be generated and accelerated without degradation. Key components are RF guns with photocathodes, bunch compressors, and related diagnostics. The status of design and construction as well as both electron and photon beam properties will be discussed. Once proven in the micrometer to nanometer regime, the SASE FEL scheme is considered applicable down to Angstrom wavelengths. It is pointed out that this latter option is particularly of interest in context with the construction of a linear collider, which requires very similar beam parameters. The status of conceptual design work on such a coherent X-ray user facility integrated into the TESLA linear collider design will be briefly sketched.

  15. Nikola Tesla Educational Opportunity School.

    ERIC Educational Resources Information Center

    Design Cost Data, 2001

    2001-01-01

    Describes the architectural design, costs, general description, and square footage data for the Nikola Tesla Educational Opportunity School in Colorado Springs, Colorado. A floor plan and photos are included along with a list of manufacturers and suppliers used for the project. (GR)

  16. Tesla - A Flash of a Genius

    NASA Astrophysics Data System (ADS)

    Teodorani, M.

    2005-10-01

    This book, which is entirely dedicated to the inventions of scientist Nikola Tesla, is divided into three parts: a) all the most important innovative technological creations from the alternate current to the death ray, Tesla research in fundamental physics with a particular attention to the concept of "ether", ball lightning physics; b) the life and the bright mind of Nikola Tesla and the reasons why some of his most recent findings were not accepted by the establishment; c) a critical discussion of the most important work by Tesla followers.

  17. [Nikola Tesla: flashes of inspiration].

    PubMed

    Villarejo-Galende, Albero; Herrero-San Martín, Alejandro

    2013-01-16

    Nikola Tesla (1856-1943) was one of the greatest inventors in history and a key player in the revolution that led to the large-scale use of electricity. He also made important contributions to such diverse fields as x-rays, remote control, radio, the theory of consciousness or electromagnetism. In his honour, the international unit of magnetic induction was named after him. Yet, his fame is scarce in comparison with that of other inventors of the time, such as Edison, with whom he had several heated arguments. He was a rather odd, reserved person who lived for his inventions, the ideas for which came to him in moments of inspiration. In his autobiography he relates these flashes with a number of neuropsychiatric manifestations, which can be seen to include migraine auras, synaesthesiae, obsessions and compulsions.

  18. [Nikola Tesla: flashes of inspiration].

    PubMed

    Villarejo-Galende, Albero; Herrero-San Martín, Alejandro

    2013-01-16

    Nikola Tesla (1856-1943) was one of the greatest inventors in history and a key player in the revolution that led to the large-scale use of electricity. He also made important contributions to such diverse fields as x-rays, remote control, radio, the theory of consciousness or electromagnetism. In his honour, the international unit of magnetic induction was named after him. Yet, his fame is scarce in comparison with that of other inventors of the time, such as Edison, with whom he had several heated arguments. He was a rather odd, reserved person who lived for his inventions, the ideas for which came to him in moments of inspiration. In his autobiography he relates these flashes with a number of neuropsychiatric manifestations, which can be seen to include migraine auras, synaesthesiae, obsessions and compulsions. PMID:23307357

  19. Electron-electron collisions at TESLA

    NASA Astrophysics Data System (ADS)

    Schreiber, Siegfried; Reyzl, Ingrid

    2001-07-01

    Electron-electron collisions at the future TESLA linear collider is a promising complement to e+e- collisions. A critical issue for the physics potential of this option is the achievable luminosity. For e+e- collisions, the pinch effect enhances the luminosity, while due to the repelling forces for e-e- collisions, the luminosity is significantly reduced and is more sensitive to beam separations. This report discusses the e-e- option for TESLA and the expected luminosity.

  20. Conduction-coupled Tesla transformer.

    PubMed

    Reed, J L

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers.

  1. Science up to 100 tesla

    SciTech Connect

    Campbell, L.J.

    1995-05-01

    100 Tesla is the highest attainable field that can be held for milli-sec in a non-destructive magnet. The strongest steels turn soft under stresses of 4GPa, which is the magnetic pressure of 100 T. Until there is a breakthrough in materials, magnets having all the low temperature and high pressure trimmings will be limited to about 100 T. Within the field range 1-100 T far more resources are now devoted to producing the highest possible continuous fields (40+5 T) than to producing longer pulsed fields above 50 T. This illustrates that the utility of the field can be more important than the strength of the field to researchers in condensed matter. Discoveries are typically made in new territory, but this can be new combinations of pressure, temperature, and magnetic field, or new probes and new materials. If any activity has kept up with the proliferation of new experiments and new facilities in high magnetic field research it is the listing of experiments that could and should be done in high fields. Part of the reason for the vitality of high field research is that high fields provide a generic environment. Compared to particle accelerators and plasma machines a high field laboratory is a setting for generic science, like synchrotron light sources or neutron scattering centers. Although the latter two installations probes states, while a magnetic field creates a state. Because it is unrealistic to try to list all the science opportunities at high fields, the author list sources for lists in the public domain and gives a few examples.

  2. Nikola Tesla, the Ether and his Telautomaton

    NASA Astrophysics Data System (ADS)

    Milar, Kendall

    2014-03-01

    In the nineteenth century physicists' understanding of the ether changed dramatically. New developments in thermodynamics, energy physics, and electricity and magnetism dictated new properties of the ether. These have traditionally been examined from the perspective of the scientists re-conceptualizing the ether. However Nikola Tesla, a prolific inventor and writer, presents a different picture of nineteenth century physics. Alongside the displays that showcased his inventions he presented alternative interpretations of physical, physiological and even psychical research. This is particularly evident in his telautomaton, a radio remote controlled boat. This invention and Tesla's descriptions of it showcase some of his novel interpretations of physical theories. He offered a perspective on nineteenth century physics that focused on practical application instead of experiment. Sometimes the understanding of physical theories that Tesla reached was counterproductive to his own inventive work; other times he offered new insights. Tesla's utilitarian interpretation of physical theories suggests a more scientifically curious and invested inventor than previously described and a connection between the scientific and inventive communities.

  3. Jakob Narkiewicz-Jodko-Tesla ``Predecessor''

    NASA Astrophysics Data System (ADS)

    Samuilov, Vladimir; Kiselev, Vladimir

    2014-03-01

    Prof. Jakob Narkiewicz-Jodko (1947-1905) is a bright figure in the history of science of the XIXth century. His major discoveries are: Electrography - the method of the visualization of electric discharge from the bodies due to the application of high strength and high frequency electric fields, and one of the first observations of the propagation of the electromagnetic waives and information transfer over the distances. We review Prof. Jakob Narkiewicz-Jodko's research results and explain our point why we consider him as the predecessor of Nikola Tesla.

  4. Nikola Tesla: the man behind the magnetic field unit.

    PubMed

    Roguin, Ariel

    2004-03-01

    The magnetic field strength of both the magnet and gradient coils used in MR imaging equipment is measured in Tesla units, which are named for Nikola Tesla. This article presents the life and achievements of this Serbian-American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating-current machinery. Nikola Tesla had 700 patents in the United States and Europe that covered every aspect of science and technology. Tesla's discoveries include the Tesla coil, AC electrical conduction, improved lighting, newer forms of turbine engines, robotics, fluorescent light, wireless transmission of electrical energy, radio, remote control, discovery of cosmic radio waves, and the use of the ionosphere for scientific purposes. He was a genius whose discoveries had a pivotal role in advancing us into the modern era.

  5. Nikola Tesla: the man behind the magnetic field unit.

    PubMed

    Roguin, Ariel

    2004-03-01

    The magnetic field strength of both the magnet and gradient coils used in MR imaging equipment is measured in Tesla units, which are named for Nikola Tesla. This article presents the life and achievements of this Serbian-American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating-current machinery. Nikola Tesla had 700 patents in the United States and Europe that covered every aspect of science and technology. Tesla's discoveries include the Tesla coil, AC electrical conduction, improved lighting, newer forms of turbine engines, robotics, fluorescent light, wireless transmission of electrical energy, radio, remote control, discovery of cosmic radio waves, and the use of the ionosphere for scientific purposes. He was a genius whose discoveries had a pivotal role in advancing us into the modern era. PMID:14994307

  6. TESLA cavity driving with FPGA controller

    NASA Astrophysics Data System (ADS)

    Czarski, Tomasz; Pozniak, Krzysztof; Romaniuk, Ryszard; Simrock, Stefan

    2005-09-01

    The digital control of the TESLA (TeV-Energy Superconducting Linear Accelerator) resonator is presented. The laboratory setup of the CHECHIA cavity in DESY-Hamburg has been driven by the FPGA (Field Programmable Gate Array) technology system. This experiment focused attention to the general recognition of the cavity features and projected control methods. The electrical model of the resonator is taken as a consideration origin. The calibration of the signal channel is considered as a key preparation for an efficient cavity driving. The identification of the resonator parameters is confirmed as a proper approach for the required performance: driving on resonance during filling and field stabilization during flattop time with reasonable power consumption. The feed-forward and feedback modes were applied successfully for the CHECHIA cavity driving. Representative results of experiments are presented for different levels of the cavity field gradient.

  7. TESLA test facility alternate cryostat design

    SciTech Connect

    Nicol, T.H.

    1996-12-31

    Collaborators on the design of a Tevatron Superconducting Linear Accelerator (TESLA) are working toward construction of a test cell consisting of four full length cryostats, 12 meters long, each consisting of eight, 9-cell superconducting RF cavities. The purpose of this facility is to test all aspects of the accelerator system design; vacuum, cryogenics, RF, and electron source, prior to initiating construction of the full linac. The design for these cryostats pose many interesting challenges to cryostat designers. The systems must be capable of supporting all eight cavity structures within tight alignment tolerances, impose very low thermal heat loads on the 1.8K cryogenic system, provide strength and stiffness to resist structural loads during fabrication, shipping, and installation, and be manufactured at low cost. Several design options are being explored, each of which attempt to address requirements imposed by the reference design guidelines. This paper describes the design and analysis of one design alternative.

  8. Nikola Tesla and the wireless transmission of energy

    SciTech Connect

    Marincic, A.S.

    1982-10-01

    Nikola Tesla, the inventor of the polyphase-current system, is best known for his contribution regarding induction and other types of alternating-current machines. His patents and his published and unpublished notes about wireless transmission of energy are less known and, if known to some extent, they are usually wrongly interpreted. For many years the author studied Tesla's works on wireless transmission of energy and that what is given here is a review of relevant documents, unpublished notes and letters from the archives of the Nikola Tesla Museum in Belgrade. An attempt is made to explain Tesla's physical model on the basis of which he concluded that the wireless transmission of energy on a global scale is possible. His model is critically examined in view of the present day knowledge of extremely low frequency propagation phenomena.

  9. Proposed applications with implementation techniques of the upcoming renewable energy resource, The Tesla Turbine

    NASA Astrophysics Data System (ADS)

    Usman Saeed Khan, M.; Maqsood, M. Irfan; Ali, Ehsan; Jamal, Shah; Javed, M.

    2013-06-01

    Recent research has shown that tesla turbine can be one of the future efficient sources of renewable energy. Modern techniques used for designing of tesla turbine have given optimum results regarding efficiency and applications. In this paper we have suggested fully coordinated applications of tesla turbine in different fields particularly in power generation at both low level and high level generation. In Energy deficient countries the tesla turbine has wide range of applications and it can play an important role in energy management system. Our proposed applications includes, the use of tesla turbine as renewable energy resource using tesla turbine in distributed generation system use of tesla turbine at home for power generation use of tesla turbine in irrigation channels using tesla turbine in hybrid electric vehicles All applications are explained with the help of flow charts and block diagrams and their implementation techniques are also explained in details. The results of physical experiments and simulations are also included for some applications.

  10. [Studies of three-dimensional cardiac late gadolinium enhancement MRI at 3.0 Tesla].

    PubMed

    Ishimoto, Takeshi; Ishihara, Masaru; Ikeda, Takayuki; Kawakami, Momoe

    2008-12-20

    Cardiac late Gadolinium enhancement MR imaging has been shown to allow assessment of myocardial viability in patients with ischemic heart disease. The current standard approach is a 3D inversion recovery sequence at 1.5 Tesla. The aims of this study were to evaluate the technique feasibility and clinical utility of MR viability imaging at 3.0 Tesla in patients with myocardial infarction and cardiomyopathy. In phantom and volunteer studies, the inversion time required to suppress the signal of interests and tissues was prolonged at 3.0 Tesla. In the clinical study, the average inversion time to suppress the signal of myocardium at 3.0 Tesla with respect to MR viability imaging at 1.5 Tesla was at 15 min after the administration of contrast agent (304.0+/-29.2 at 3.0 Tesla vs. 283.9+/-20.9 at 1.5 Tesla). The contrast between infarction and viable myocardium was equal at both field strengths (4.06+/-1.30 at 3.0 Tesla vs. 4.42+/-1.85 at 1.5 Tesla). Even at this early stage, MR viability imaging at 3.0 Tesla provides high quality images in patients with myocardial infarction. The inversion time is significantly prolonged at 3.0 Tesla. The contrast between infarction and viable myocardium at 3.0 Tesla are equal to 1.5 Tesla. Further investigation is needed for this technical improvement, for clinical evaluation, and for limitations.

  11. Report on the TESLA Engineering Study/Review

    SciTech Connect

    Cornuelle, John C.

    2002-08-30

    In March, 2001, the TESLA Collaboration published its Technical Design Report (TDR, see references and links in Appendix), the first sentence of which stated ''...TESLA (TeV-Energy Superconducting Linear Collider) (will be) a superconducting electron-positron collider of initially 500 GeV total energy, extendable to 800 GeV, and an integrated X-ray laser laboratory.'' The TDR included cost and manpower estimates for a 500 GeV e{sup +}e{sup -} collider (250 on 250 GeV) based on superconducting RF cavity technology. This was submitted as a proposal to the German government. The government asked the German Science Council to evaluate this proposal. The recommendation from this body is anticipated to be available by November 2002. The government has indicated that it will react on this recommendation by mid-2003. In June 2001, Steve Holmes, Fermilab's Associate Director for Accelerators, commissioned Helen Edwards and Peter Garbincius to organize a study of the TESLA Technical Design Report and the associated cost and manpower estimates. Since the elements and methodology used in producing the TESLA cost estimate were somewhat different from those used in preparing similar estimates for projects within the U.S., it is important to understand the similarities, differences, and equivalences between the TESLA estimate and U.S. cost estimates. In particular, the project cost estimate includes only purchased equipment, materials, and services, but not manpower from DESY or other TESLA collaborating institutions, which is listed separately. It does not include the R&D on the TESLA Test Facility (TTF) nor the costs of preparing the TDR nor the costs of performing the conceptual studies so far. The manpower for the pre-operations commissioning program (up to beam) is included in the estimate, but not the electrical power or liquid Nitrogen (for initial cooldown of the cryogenics plant). There is no inclusion of any contingency or management reserve. If the U.S. were to become

  12. Paul Drude's prediction of nonreciprocal mutual inductance for Tesla transformers.

    PubMed

    McGuyer, Bart

    2014-01-01

    Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed.

  13. Paul Drude's Prediction of Nonreciprocal Mutual Inductance for Tesla Transformers

    PubMed Central

    McGuyer, Bart

    2014-01-01

    Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed. PMID:25542040

  14. Time Synchronization in Hierarchical TESLA Wireless Sensor Networks

    SciTech Connect

    Jason L. Wright; Milos Manic

    2009-08-01

    Time synchronization and event time correlation are important in wireless sensor networks. In particular, time is used to create a sequence events or time line to answer questions of cause and effect. Time is also used as a basis for determining the freshness of received packets and the validity of cryptographic certificates. This paper presents secure method of time synchronization and event time correlation for TESLA-based hierarchical wireless sensor networks. The method demonstrates that events in a TESLA network can be accurately timestamped by adding only a few pieces of data to the existing protocol.

  15. 76 FR 60124 - Tesla Motors, Inc.; Grant of Petition for Temporary Exemption From the Electronic Stability...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... entering the fleet. IV. Notice of Receipt On August 5, 2011, we published in the Federal Register (76 FR... TRANSPORTATION National Highway Traffic Safety Administration Tesla Motors, Inc.; Grant of Petition for Temporary... Stability Control Systems. SUMMARY: This notice grants the petition of Tesla Motors, Inc. (Tesla) for...

  16. Test of the DEP hybrid photodiode in 5 Tesla Magnet

    SciTech Connect

    Green, D; Freeman, J.; Ronzhin, A.; Cushman, R.; Heering, A.

    1997-10-01

    The CMS detector is designed so that the tile/fiber hadronic calorimeter (HCAL) is immersed in a 4 Tesla magnetic field. The Hybrid Photodiode (HPD) will be used as the photodetector. Below we present the experiment data which we obtained on the HPD behavior in a magnetic field.

  17. Identifying Needed Technical Standards: The LITA TESLA Committee at Work.

    ERIC Educational Resources Information Center

    Carter, Ruth C.

    1984-01-01

    Efforts of the Technical Standards for Library Automation Committee (TESLA), a division-wide committee of the Library Information and Technology Association (LITA) of the American Library Association, are described. The current status of suggested technical standards and recommended action are detailed. Five sources are given. (Author/EJS)

  18. Tesla coil discharges guided by femtosecond laser filaments in air

    NASA Astrophysics Data System (ADS)

    Brelet, Yohann; Houard, Aurélien; Arantchouk, Leonid; Forestier, Benjamin; Liu, Yi; Prade, Bernard; Carbonnel, Jérôme; André, Yves-Bernard; Mysyrowicz, André

    2012-04-01

    A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the discharges are performed in air by femtosecond laser filaments.

  19. Functionality of veterinary identification microchips following low- (0.5 tesla) and high-field (3 tesla) magnetic resonance imaging.

    PubMed

    Piesnack, Susann; Frame, Mairi E; Oechtering, Gerhard; Ludewig, Eberhard

    2013-01-01

    The ability to read patient identification microchips relies on the use of radiofrequency pulses. Since radiofrequency pulses also form an integral part of the magnetic resonance imaging (MRI) process, the possibility of loss of microchip function during MRI scanning is of concern. Previous clinical trials have shown microchip function to be unaffected by MR imaging using a field strength of 1 Tesla and 1.5. As veterinary MRI scanners range widely in field strength, this study was devised to determine whether exposure to lower or higher field strengths than 1 Tesla would affect the function of different types of microchip. In a phantom study, a total of 300 International Standards Organisation (ISO)-approved microchips (100 each of three different types: ISO FDX-B 1.4 × 9 mm, ISO FDX-B 2.12 × 12 mm, ISO HDX 3.8 × 23 mm) were tested in a low field (0.5) and a high field scanner (3.0 Tesla). A total of 50 microchips of each type were tested in each scanner. The phantom was composed of a fluid-filled freezer pack onto which a plastic pillow and a cardboard strip with affixed microchips were positioned. Following an MRI scan protocol simulating a head study, all of the microchips were accurately readable. Neither 0.5 nor 3 Tesla imaging affected microchip function in this study.

  20. A 10 tesla table-top controlled waveform magnet.

    PubMed

    Roy Choudhury, Aditya N; Venkataraman, V

    2012-04-01

    Controlled waveform magnets (CWMs) are a class of pulsed magnets whose pulse shape with time can be programmed by the user. With a CWM, the user gains control not only over the magnitude of the field but also over its rate of change. In this work we present a table-top CWM, driven by a capacitor bank, capable of producing virtually any user-shaped magnetic field waveform up to 10 tesla. Insulated gate bipolar transistor chips have been paralleled to form the high current switch and paralleled chips of SiC Schottky diodes form the crowbar diode module. Sample controlled waveforms including flat-tops up to 10 tesla and some triangular magnetic field pulses have been successfully generated for 10-20 ms with a ripple <1%. PMID:22559572

  1. Six tesla analyzing magnet for heavy-ion beam transport

    SciTech Connect

    Smith, R.P.; Bollinger, L.; Erskine, J.; Genens, L.; Hoffman, J.

    1980-01-01

    A superconducting analyzer magnet for particle beam deflection has been designed and is being fabricated for use at the Argonne Tandem-Linac Accelerator System (ATLAS). This six tesla magnet will provide 45/sup 0/ of deflection for the heavy-ion beams from the ATLAS tandem electrostatic accelerator and together with its twin will replace the existing conventional 90/sup 0/ analyzer magnet which will become inadequate when ATLAS is completed.

  2. RHQT Nb3Al 15-Tesla magnet design study

    SciTech Connect

    Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

    2005-09-01

    Feasibility study of 15-Tesla dipole magnets wound with a new copper stabilized RHQT Nb{sub 3}Al Rutherford cable is presented. A new practical long copper stabilized RHQT Nb{sub 3}Al strand is presented, which is being developed and manufactured at the National Institute of Material Science (NIMS) in Japan. It has achieved a non-copper J{sub c} of 1000A/mm{sup 2} at 15 Tesla at 4.2K, with a copper over non-copper ratio of 1.04, and a filament size less than 50 microns. For this design study a short Rutherford cable with 28 Nb{sub 3}Al strands of 1 mm diameter will be fabricated late this year. The cosine theta magnet cross section is designed using ROXIE, and the stress and strain in the coil is estimated and studied with the characteristics of the Nb{sub 3}Al strand. The advantages and disadvantages of the Nb{sub 3}Al cable are compared with the prevailing Nb{sub 3}Sn cable from the point of view of stress-strain, J{sub c}, and possible degradation of stabilizer due to cabling. The Nb{sub 3}Al coil of the magnet, which will be made by wind and react method, has to be heat treated at 800 degree C for 10 hours. As preparation for the 15 Tesla magnet, a series of tests on strand and Rutherford cables are considered.

  3. Chemical shift imaging of atherosclerosis at 7.0 Tesla.

    PubMed

    Maynor, C H; Charles, H C; Herfkens, R J; Suddarth, S A; Johnson, G A

    1989-01-01

    Chemical shift imaging (CSI) was performed on cadaveric atherosclerotic fibrous plaques, periaortic adipose tissue, and cholesterol standards using a 7.0 Tesla horizontal bore prototype imaging spectrometer. Proton spectroscopy of intact tissue and deuterated chloroform extracted samples was done at the equivalent field strength of 7.0 Tesla on a vertical bore spectrometer, including studies of temperature dependence and T2 relaxation measurements. Spectra obtained using CSI on the imaging magnet were comparable with those from the conventional vertical spectrometer. Fibrous plaques and adipose tissue had unique spectral features, differing in the ratios of their water and various fat components. Chloroform extractions revealed a typical cholesteric ester spectrum for the fibrous plaque in contrast to the triglyceride spectrum of the adipose tissue. These two tissues also had different T2 relaxation measurements of their major fat resonances, with fibrous plaques having a short T2 compared to adipose tissue (15.9 milliseconds vs. 46.2 milliseconds). Temperature dependence studies showed that spectral signal intensity of the fat resonance of the fibrous plaque increased while linewidth decreased with increasing temperature from 24 degrees C to 37 degrees C. Atherosclerotic lesions may be studied at 7.0 Tesla, and NMR parameters defined in the present study may be used for further studies at other magnetic field strengths.

  4. Improved surface treatment of the superconducting TESLA cavities

    NASA Astrophysics Data System (ADS)

    Lilje, L.; Antoine, C.; Benvenuti, C.; Bloess, D.; Charrier, J.-P.; Chiaveri, E.; Ferreira, L.; Losito, R.; Matheisen, A.; Preis, H.; Proch, D.; Reschke, D.; Safa, H.; Schmüser, P.; Trines, D.; Visentin, B.; Wenninger, H.

    2004-01-01

    The proposed linear electron-positron collider TESLA is based on 1.3 GHz superconducting niobium cavities for particle acceleration. For a centre-of-mass energy of 500 GeV, an accelerating field of 23.4 MV/m is required which is reliably achieved with a niobium surface preparation by chemical etching. An upgrade of the collider to 800 GeV requires an improved cavity preparation technique. In this paper, results are presented on single-cell cavities which demonstrate that fields of up to 40 MV/m are accessible by electrolytic polishing of the inner surface of the cavity.

  5. Field quality measurements of a 2-Tesla transmission line magnet

    SciTech Connect

    Velev, G.V.; Foster, W.; Kashikhin, V.; Mazur, P.; Oleck, A.; Piekarz, H.; Schlabach, P.; Sylvester, C.; Wake, M.; /KEK, Tsukuba

    2005-09-01

    A prototype 2-Tesla superconducting transmission line magnet for future hadron colliders was designed, built and tested at Fermilab. The 1.5 m long, combined-function gradient-dipole magnet has a vertical pole aperture of 20 mm. To measure the magnetic field quality in such a small magnet aperture, a specialized rotating coil of 15.2 mm diameter, 0.69 m long was fabricated. Using this probe, a program of magnetic field quality measurements was successfully performed. Results of the measurements are presented and discussed.

  6. Status of the NHMFL 60 tesla quasi-continuous magnet

    SciTech Connect

    Campbell, L.J.; Boenig, H.J.; Rickel, D.G.; Schilig, J.B.; Sims, J.R.; Schneider-Muntau, H.J.

    1995-07-01

    All components of the National High Magnetic Field Laboratory`s (NHMFL) 60 T quasi-continuous magnet are now under construction, with complete delivery and installation expected in early 1996. This research magnet has a cold bore of 32 mm and will produce a constant 60 tesla for 100 ms plus a wide variety of other pulse shapes such as linear ramps, steps, crowbar decays, and longer flat-tops at lower fields. Fabrication and testing of prototype coils are described along with the layout, construction status, and protection philosophy of the 400 MW power supply. Examples of simulated pulse shapes are shown.

  7. B > 1 Tesla low mass magnetic field sweep assembly

    NASA Astrophysics Data System (ADS)

    Cadieu, F. J.; Heremans, J. J.; Griffin, J.; Caldwell, C.; von Molnar, S.

    1997-03-01

    We have designed, modeled and tested a variable magnetic field sweep unit over a wide temperature range, from cryogenic to 100 C. The unit provides a sweepable uniform magnetic field, independent of temperature, over an air gap of 2 mm and spatial extent of 4 mm x 4 mm. It consists of a small magnet yoke structure and a spur gear driven rotatable magnet to vary the gap field in a nearly sinusoidal manner as a function of the magnet rotation angle. In the present design a 20 g SmCo magnet has been used, which allows for low temperature operation to 15 K when attached to a cryogenic refrigerator cold finger. The shape of the magnetic yoke structure has been modeled and optimized using 3-D magnetic field software. The gap field uniformity can thus be modeled and tested experimentally. In a present working model (2 mm gap) the field B(θ) = 1.0 sin(θ) (Tesla) where θ is the magnet rotation angle. With 0.25 mm thick permunder pole tips the field amplitude has been increased to 1.2 Tesla over a gap of 1.5 mm.

  8. Coaxial Coupling Scheme for TESLA/ILC-type Cavities

    SciTech Connect

    J.K. Sekutowicz, P. Kneisel

    2010-05-01

    This paper reports about our efforts to develop a flangeable coaxial coupler for both HOM and fundamental coupling for 9-cell TESLA/ILC-type cavities. The cavities were designed in early 90‘s for pulsed operation with a low duty factor, less than 1 %. The proposed design of the coupler has been done in a way, that the magnetic flux B at the flange connection is minimized and only a field of <5 mT would be present at the accelerating field Eacc of ~ 36 MV/m (B =150 mT in the cavity). Even though we achieved reasonably high Q-values at low field, the cavity/coupler combination was limited in the cw mode to only ~ 7 MV/m, where a thermally initiated degradation occurred. We have improved the cooling conditions by initially drilling radial channels every 30 degrees, then every 15 degrees into the shorting plate. The modified prototype performed well up to 9 MV/m in cw mode. This paper reports about our experiences with the further modified coaxial coupler and about test results in cw and low duty cycle pulsed mode, similar to the TESLA/ILC operation conditions.

  9. Searchers for a new energy source; Tesla, Moray, and Bearden

    SciTech Connect

    Johnson, G.L. )

    1992-01-01

    Tesla, Moray, Bearden, and others have claimed the existence of another source of energy besides those presently in use. Like sun and wind, this source is available without regard to political boundaries. If true, the development of this energy source would be one of the most important events of the century. It seems that every time mankind reaches a limit of growth due to exhaustion of inexpensive energy supplies, another energy sources is discovered and developed. England had essentially depleted its resources of timber when the technology to mine and burn coal was developed, for example. After coal, technologies for oil, gas, hydro, nuclear fission, wind, photovoltaic, etc. were developed. With each new development, the world was able to support a greater population at a higher standard of living than before. Today, however, many developing countries have reached a limit in improving the quality of life, due in part to the lack of an adequate and economical energy supply. The developed nations are worried about global warming, acid rain, and nuclear waste. The recent excitement about cold fusion illustrated the keen desire for a new energy source, one operating on scientific principles that perhaps are unknown or poorly developed at the present time. a number of researchers have claimed that such a new energy sources exists. This source would be in addition to cold fusion if cold fusion is shown to be valid. Three of the most famous researchers with this belief have been Tesla, Moray, and Bearden. This article discusses each of their concepts.

  10. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field.

    PubMed

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L; Miloushev, Vesselin; Poot, Alex J; Truong, Steven; Alvarez, Julio A; Aldeborgh, Hannah N; Keshari, Kayvan R

    2016-01-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting (13)C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength. PMID:27597137

  11. Report on the TESLA engineering study/review

    SciTech Connect

    C. Boffo et al.

    2002-07-18

    A team from Argonne National Lab, Cornell, Fermilab, Jefferson Lab, and SLAC has studied the TESLA TDR and its associated cost and manpower estimates, concentrating on the five largest cost sub-systems (Main Linac Modules, Main Linac RF Systems, Civil Engineering, Machine Infrastructure, and XFEL Incremental). These elements were concerned mainly with providing energy reach. We did not study the lower cost, but still technically challenging elements providing luminosity and physics capability, namely damping rings, beam delivery system, beam injection system, positron production, polarized beams, etc. The study did not attempt to validate the TDR cost estimates, but rather its purpose was to understand the technology and status of the large cost items, and the methodology by which their estimated cost was determined. In addition, topics of project oversight were studied.

  12. Comparison of the TESLA, NLC and CLIC beam collimation performance

    SciTech Connect

    Alexandr I Drozhdin et al.

    2003-03-27

    This note describes studies performed in the framework of the Collimation Task Force organized to support the work of the International Linear Collider Technical Review Committee. The post-linac beam-collimation systems in the TESLA, JLC/NLC and CLIC linear-collider designs are compared using the same computer code under the same assumptions. Their performance is quantified in terms of beam-halo and synchrotron-radiation collimation efficiency. The performance of the current designs varies across projects, and does not always meet the original design goals. But these comparisons suggest that achieving the required performance in a future linear collider is feasible. The post-TRC plans of the Collimation Task Force are briefly outlined in closing.

  13. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field

    NASA Astrophysics Data System (ADS)

    Tee, Sui Seng; Digialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L.; Miloushev, Vesselin; Poot, Alex J.; Truong, Steven; Alvarez, Julio A.; Aldeborgh, Hannah N.; Keshari, Kayvan R.

    2016-09-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting 13C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  14. A Single Crystal Niobium RF Cavity of the TESLA Shape

    SciTech Connect

    W. Singer; X. Singer; P. Kneisel

    2007-09-01

    A fabrication method for single crystal niobium cavities of the TESLA shape was proposed on the basis of metallographic investigations and electron beam welding tests on niobium single crystals. These tests showed that a cavity can be produced without grain boundaries even in the welding area. An appropriate annealing allows the outgassing of hydrogen and stress relaxation of the material without destruction of the single crystal. A prototype single crystal single cell cavity was built. An accelerating gradient of 37.5 MV/m was reached after approximately 110 mu-m of Buffered Chanical Polishing (BCP) and in situ baking at 120°C for 6 hrs with a quality factor exceeding 2x1010 at 1.8 K. The developed fabrication method can be extended to fabrication of multi cell cavities.

  15. A Single Crystal Niobium RF Cavity of the TESLA Shape

    SciTech Connect

    Singer, W.; Singer, X.; Kneisel, P.

    2007-08-09

    A fabrication method for single crystal niobium cavities of the TESLA shape was proposed on the basis of metallographic investigations and electron beam welding tests on niobium single crystals. These tests showed that a cavity can be produced without grain boundaries even in the welding area. An appropriate annealing allows the outgassing of hydrogen and stress relaxation of the material without destruction of the single crystal. A prototype single crystal single cell cavity was build. An accelerating gradient of 37.5 MV/m was reached after approximately 110 {mu}m of Buffered Chemical Polishing (BCP) and in situ baking at 120 deg. C for 6 hrs with a quality factor exceeding 2x1010 at 1.8 K. The developed fabrication method can be extended to fabrication of multi cell cavities.

  16. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field.

    PubMed

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L; Miloushev, Vesselin; Poot, Alex J; Truong, Steven; Alvarez, Julio A; Aldeborgh, Hannah N; Keshari, Kayvan R

    2016-09-06

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting (13)C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  17. The NHMFL 60 tesla, 100 millisecond pulsed magnet

    SciTech Connect

    Boenig, H.J.; Campbell, L.J.; Rickel, D.G.; Rogers, J.D.; Schillig, J.B.; Sims, J.R.; Pernambuco-Wise, P.; Schneider-Muntau, H.J.

    1992-11-09

    Among the new facilities to be offered by the National Science Foundation through the National High Magnetic Field Laboratory (NHMFL) are pulsed fields that can only be achieved at a national user facility by virtue of their strength, duration, and volume. In particular, a 44 mm bore pulsed magnet giving a 60 tesla field for 100 ms is in the final design stage. This magnet will be powered by a 1.4 GW motor-generator at Los Alamos and is an important step toward proving design principles that will be needed for the higher field quasi-stationary pulsed magnets that this power source is capable of driving. This report will discuss specifications and parameters of this magnet.

  18. Design and prototype fabrication of a 30 tesla cryogenic magnet

    NASA Technical Reports Server (NTRS)

    Prok, G. M.; Swanson, M. C.; Brown, G. V.

    1977-01-01

    A liquid neon cooled magnet was designed to produce 30 teslas in steady operation. To ensure the correctness of the heat transfer relationships used, supercritical neon heat transfer tests were made. Other tests made before the final design included tests on the effect of the magnetic field on pump motors, tensile shear tests on the cryogenic adhesives, and simulated flow studies for the coolant. The magnet will consist of two pairs of coils, cooled by forced convection of supercritical neon. Heat from the supercritical neon will be rejected through heat exchangers which are made of roll bonded copper panels and are submerged in a pool of saturated liquid neon. A partial mock up coil was wound to identify the tooling required to wind the magnet. This was followed by winding a prototype pair of coils. The prototype winding established procedures for fabricating the final magnet and revealed slight changes needed in the final design.

  19. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field

    PubMed Central

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L.; Miloushev, Vesselin; Poot, Alex J.; Truong, Steven; Alvarez, Julio A.; Aldeborgh, Hannah N.; Keshari, Kayvan R.

    2016-01-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting 13C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength. PMID:27597137

  20. MRI at 7 Tesla and above: demonstrated and potential capabilities.

    PubMed

    Kraff, Oliver; Fischer, Anja; Nagel, Armin M; Mönninghoff, Christoph; Ladd, Mark E

    2015-01-01

    With more than 40 installed MR systems worldwide operating at 7 Tesla or higher, ultra-high-field (UHF) imaging has been established as a platform for clinically oriented research in recent years. Along with technical developments that, in part, have also been successfully transferred to lower field strengths, MR imaging and spectroscopy at UHF have demonstrated capabilities and potentials for clinical diagnostics in a variety of studies. In terms of applications, this overview article focuses on already achieved advantages for in vivo imaging, i.e., in imaging the brain and joints of the musculoskeletal system, but also considers developments in body imaging, which is particularly challenging. Furthermore, new applications for clinical diagnostics such as X-nuclei imaging and spectroscopy, which only really become feasible at ultra-high magnetic fields, will be presented.

  1. Beamstrahlung Photon Load on the TESLA Extraction Septum Blade(LCC-0104)

    SciTech Connect

    Seryi, A

    2003-10-02

    This note describes work performed in the framework of the International Linear Collider Technical Review Committee [1] to estimate the power load on the TESLA extraction septum blade due to beamstrahlung photons. It is shown, that under realistic conditions the photon load can be several orders of magnitude higher than what was estimated in the TESLA TDR [2] for the ideal Gaussian beams, potentially representing a serious limitation of the current design.

  2. Team one (GA/MCA) effort of the DOE 12 Tesla Coil Development Program. 12 Tesla ETF toroidal field coil helium bath cooled NbTi alloy concept

    SciTech Connect

    Not Available

    1980-07-01

    This report presents the conceptual design of an ETF compatible toroidal field coil, employing helium bath cooled NbTi alloy conductor. The ten TF-coil array generates a peak field of 11-1/2 tesla at 2.87 m radius, corresponding to a major axis field of 6.1 tesla. The 10 kA conductor is an uninsulated, unsoldered Rutherford cable, employing NbTiTa ally as developed in Phase I of this effort. The conductor is encased within a four element frame of stainless steel strips to provide hoop and bearing load support.

  3. Feasibility Study of a HOM IOT for TESLA

    NASA Astrophysics Data System (ADS)

    Schütt, Petra; Weiland, Thomas; Gamp, Alexander; Lu, Fuhai

    1997-05-01

    For the TESLA linear collider 1.3 GHz RF sources with 10 MW peak power and about 70% efficiency are needed. As an alternative to the development of a Multibeam-Klystron, we investigate the feasibility of an IOT (Inductive Output Tube). This is a very compact RF source: The time structure of the beam is produced by a gated emission cathode and the output cavity is directly adjacent to the anode. Unlike IOTs, conventional klystrons lose some of their design efficiency when they are operated below saturation, because only the RF component of the beam is reduced and not the DC beam current. In contrast to this the cathode current of an IOT is controlled by the drive power. In order to keep the gun voltage low, we investigate a device with a hollow beam where the output cavity is excited in a higher order mode (HOM), as was recently suggested by CPI(E.Lien, H.Bohlen, US Patent Application Serial No. 08/413,034). Computer simulations are carried out with the CAD-system MAFIA. First, an existing Klystrode TM IOT built by CPI is analysed. Simulation results will be shown and compared to experimental data. Based upon this experience, a design strategy is discussed for the HOM IOT.

  4. Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger

    2012-01-01

    Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

  5. Design and prototype fabrication of a 30 tesla cryogenic magnet

    NASA Technical Reports Server (NTRS)

    Prok, G. M.; Swanson, M. C.; Brown, G. V.

    1977-01-01

    A liquid-neon-cooled magnet has been designed to produce 30 teslas in steady operation. Its feasibility was established by a previously reported parametric study. To ensure the correctness of the heat transfer relationships used, supercritical neon heat transfer tests were made. Other tests made before the final design included tests on the effect of the magnetic field on pump motors; tensile-shear tests on the cryogenic adhesives; and simulated flow studies for the coolant. The magnet will be made of two pairs of coils, cooled by forced convection of supercritical neon. Heat from the supercritical neon will be rejected through heat exchangers which are made of roll-bonded copper panels and are submerged in a pool of saturated liquid neon. A partial mock-up coil was wound to identify the tooling required to wind the magnet. This was followed by winding a prototype pair of coils. The prototype winding established procedures for fabricating the final magnet and revealed slight changes needed in the final design.

  6. A Passively-Suspended Tesla Pump Left Ventricular Assist Device

    PubMed Central

    Izraelev, Valentin; Weiss, William J.; Fritz, Bryan; Newswanger, Raymond K.; Paterson, Eric G.; Snyder, Alan; Medvitz, Richard B.; Cysyk, Joshua; Pae, Walter E.; Hicks, Dennis; Lukic, Branka; Rosenberg, Gerson

    2009-01-01

    The design and initial test results of a new passively suspended Tesla type LAVD blood pump are described. CFD analysis was used in the design of the pump. Overall size of the prototype device is 50 mm in diameter and 75 mm in length. The pump rotor has a density lower than that of blood and when spinning inside the stator in blood it creates a buoyant centering force that suspends the rotor in the radial direction. The axial magnetic force between the rotor and stator restrain the rotor in the axial direction. The pump is capable of pumping up to 10 liters/min at a 70 mmHg head rise at 8000 RPM. The pump has demonstrated a normalized index of hemolysis level below .02 mg/dL for flows between 2 and 9.7 L/min. An inlet pressure sensor has also been incorporated into the inlet cannula wall and will be used for control purposes. One initial in vivo study showed an encouraging result. Further CFD modeling refinements are planned as well as endurance testing of the device. PMID:19770799

  7. [Examination of upper abdominal region in high spatial resolution diffusion-weighted imaging using 3-Tesla MRI].

    PubMed

    Terada, Masaki; Matsushita, Hiroki; Oosugi, Masanori; Inoue, Kazuyasu; Yaegashi, Taku; Anma, Takeshi

    2009-03-20

    The advantage of the higher signal-to-noise ratio (SNR) of 3-Tesla magnetic resonance imaging (3-Tesla) has the possibility of contributing to the improvement of high spatial resolution without causing image deterioration. In this study, we compared SNR and the apparent diffusion coefficient (ADC) value with 3-Tesla as the condition in the diffusion-weighted image (DWI) parameter of the 1.5-Tesla magnetic resonance imaging (1.5-Tesla) and we examined the high spatial resolution images in the imaging method [respiratory-triggering (RT) method and breath free (BF) method] and artifact (motion and zebra) in the upper abdominal region of DWI at 3-Tesla. We have optimized scan parameters based on phantom and in vivo study. As a result, 3-Tesla was able to obtain about 1.5 times SNR in comparison with the 1.5-Tesla, ADC value had few differences. Moreover, the RT method was effective in correcting the influence of respiratory movement in comparison with the BF method, and image improvement by the effective acquisition of SNR and reduction of the artifact were provided. Thus, DWI of upper abdominal region was a useful sequence for the high spatial resolution in 3-Tesla.

  8. Diagnostic usefulness of 3 tesla MRI of the brain for cushing disease in a child.

    PubMed

    Ono, Erina; Ozawa, Ayako; Matoba, Kaori; Motoki, Takanori; Tajima, Asako; Miyata, Ichiro; Ito, Junko; Inoshita, Naoko; Yamada, Syozo; Ida, Hiroyuki

    2011-10-01

    It is sometimes difficult to confirm the location of a microadenoma in Cushing disease. Recently, we experienced an 11-yr-old female case of Cushing disease with hyperprolactinemia. She was referred to our hospital because of decrease of height velocity with body weight gain. On admission, she had typical symptoms of Cushing syndrome. Although no pituitary microadenomas were detected on 1.5 Tesla MRI of the brain, endocrinological examinations including IPS and CS sampling were consistent with Cushing disease with hyperprolactinemia. Oral administration of methyrapone instead of neurosurgery was started after discharge, but subsequent 3 Tesla MRI of the brain clearly demonstrated a 3-mm less-enhanced lesion in the left side of the pituitary gland. Finally, transsphenoidal surgery was performed, and a 3.5-mm left-sided microadenoma was resected. Compared with 1.5 Tesla MRI, 3 Tesla MRI offers the advantage of a higher signal to noise ratio (SNR), which provides higher resolution and proper image quality. Therefore, 3 Tesla MRI is a very useful tool to localize microadenomas in Cushing disease in children as well as in adults. It will be the first choice of radiological examinations in suspected cases of Cushing disease.

  9. The pioneers of interplanetary communication: From Gauss to Tesla

    NASA Astrophysics Data System (ADS)

    Raulin-Cerceau, Florence

    2010-12-01

    The present overview covers the period from 1820 to the beginning of the 20th century. Emphasis is laid on the latter half of the 19th century because many efforts have been done at that time to elaborate schemes for contacting our neighboring planets by interplanetary telegraphy. This period knew many advances not only in planetary studies but also in the nascent field of telecommunications. Such a context led astronomers who were also interested in the problem of planetary habitability, to envisage that other planets could be contacted, especially the planet Mars. Interplanetary communication using a celestial telegraphy was planned during this period of great speculations about life on Mars. This paper focuses on four authors: the Frenchmen C. Flammarion, Ch. Cros, A. Mercier and the Serbian N. Tesla, who formulated early proposals to communicate with Mars or Venus. The first proposals (which remained only theoretical) showed that an initial reflection had started as early as the second part of the 19th century on the type of language that could be both universal and distinguishable from a natural signal. Literary history of interplanetary communication preceded by far the scientific one. Authors of the 1900s were very prolific on this topic. French fictions are mentioned in this paper as examples of such a literature. This incursion into selected texts stresses the fact that the problem of techniques and messages employed to communicate with other planets goes beyond the strict scientific framework. Finally, this paper aims to highlight the similarities as well as the differences between the different proposals and to underline what that could possibly help present SETI research to define messages supposed to be sent to other planetary systems.

  10. Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics

    NASA Astrophysics Data System (ADS)

    Veda Prakash, G.; Kumar, R.; Patel, J.; Saurabh, K.; Shyam, A.

    2013-12-01

    In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results.

  11. Liquid neon heat transfer as applied to a 30 tesla cryomagnet

    NASA Technical Reports Server (NTRS)

    Papell, S. S.; Hendricks, R. C.

    1975-01-01

    Since superconducting magnets cooled by liquid helium are limited to magnetic fields of about 18 teslas, the design of a 30 tesla cryomagnet necessitates forced convection liquid neon heat transfer in small coolant channels. As these channels are too small to handle the vapor flow if the coolant were to boil, the design philosophy calls for suppressing boiling by subjecting the fluid to high pressures. Forced convection heat transfer data are obtained by using a blowdown technique to force the fluid vertically through a resistance-heated instrumented tube. The data are obtained at inlet temperatures between 28 and 34 K and system pressures between 28 to 29 bars. Data correlation is limited to a very narrow range of test conditions, since the tests were designed to simulate the heat transfer characteristics in the coolant channels of the 30 tesla cryomagnet concerned. The results can therefore be applied directly to the design of the magnet system.-

  12. Cold- and Beam Test of the First Prototypes of the Superstructure for the TESLA Collider

    SciTech Connect

    Baboi, Nicoleta

    2003-08-08

    After three years of preparation, two superstructures, each made of two superconducting 7-cell weakly coupled subunits, have been installed in the TESLA Test Facility linac (TTF) for the cold- and beam-test. The energy stability, the HOMs damping, the frequency and the field adjustment methods were tested. The measured results confirmed expectation on the superstructure performance and proved that alternative layout for the 800 GeV upgrade of the TESLA collider, as it was proposed in TDR, is feasible. We report on the test and give here an overview of its results which are commented in more detail elsewhere in these Proceedings.

  13. Magnetic Semiconductor Quantum Wells in High Fields to 60 Tesla: Photoluminescence Linewidth Annealing at Magnetization Steps

    SciTech Connect

    Awschalom, D.D.; Crooker, S.A.; Lyo, S.K.; Rickel, D.G.; Samarth, N.

    1999-05-24

    Magnetic semiconductors offer a unique possibility for strongly tuning the intrinsic alloy disorder potential with applied magnetic field. We report the direct observation of a series of step-like reductions in the magnetic alloy disorder potential in single ZnSe/Zn(Cd,Mn)Se quantum wells between O and 60 Tesla. This disorder, measured through the linewidth of low temperature photoluminescence spectra drops abruptly at -19, 36, and 53 Tesla, in concert with observed magnetization steps. Conventional models of alloy disorder (developed for nonmagnetic semiconductors) reproduce the general shape of the data, but markedly underestimate the size of the linewidth reduction.

  14. 3.0 Tesla vs 1.5 Tesla breast magnetic resonance imaging in newly diagnosed breast cancer patients

    PubMed Central

    Butler, Reni S; Chen, Christine; Vashi, Reena; Hooley, Regina J; Philpotts, Liane E

    2013-01-01

    AIM: To compare 3.0 Tesla (T) vs 1.5T magnetic resonance (MR) imaging systems in newly diagnosed breast cancer patients. METHODS: Upon Institutional Review Board approval, a Health Insurance Portability and Accountability Act-compliant retrospective review of 147 consecutive 3.0T MR examinations and 98 consecutive 1.5T MR examinations in patients with newly diagnosed breast cancer between 7/2009 and 5/2010 was performed. Eleven patients who underwent neoadjuvant chemotherapy in the 3.0T group were excluded. Mammographically occult suspicious lesions (BIRADS Code 4 and 5) additional to the index cancer in the ipsilateral and contralateral breast were identified. Lesion characteristics and pathologic diagnoses were recorded, and results achieved with both systems compared. Statistical significance was analyzed using Fisher’s exact test. RESULTS: In the 3.0T group, 206 suspicious lesions were identified in 55% (75/136) of patients and 96% (198/206) of these lesions were biopsied. In the 1.5T group, 98 suspicious lesions were identified in 53% (52/98) of patients and 90% (88/98) of these lesions were biopsied. Biopsy results yielded additional malignancies in 24% of patients in the 3.0T group vs 14% of patients in the 1.5T group (33/136 vs 14/98, P = 0.07). Average size and histology of the additional cancers was comparable. Of patients who had a suspicious MR imaging study, additional cancers were found in 44% of patients in the 3.0T group vs 27% in the 1.5T group (33/75 vs 14/52, P = 0.06), yielding a higher positive predictive value (PPV) for biopsies performed with the 3.0T system. CONCLUSION: 3.0T MR imaging detected more additional malignancies in patients with newly diagnosed breast cancer and yielded a higher PPV for biopsies performed with the 3.0T system. PMID:24003354

  15. 76 FR 47639 - Tesla Motors, Inc.; Receipt of Petition for Temporary Exemption From the Electronic Stability...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    ... fatal single-vehicle crashes of passenger cars by 36 percent and fatal single-vehicle crashes of sport..., where installation of the power train and other final steps are taken prior to sale of the vehicle in... Roadster is a low, two-seat sport coupe. Tesla believes that, while the Roadster is capable of...

  16. Design study of 15-Tesla RHQT Nb3Al block type dipole magnet

    SciTech Connect

    Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

    2005-09-01

    The design study of the block type 15-Tesla RHQT Nb{sub 3}Al dipole magnet, and its merits over Nb{sub 3}Sn magnets are presented. The copper stabilized RHQT Nb{sub 3}Al strand is now becoming commercially available for the application to the accelerator magnets. A 1 mm diameter RHQT Nb{sub 3}Al strand with filament size about 50 {mu}, non-copper Jc about 1000 A/mm{sup 2} at 15 Tesla at 4.2K, copper ratio of 50%, can now be produced over several hundred meters. The stress and strain characteristics of the Nb{sub 3}Al strand are superior to the Nb{sub 3}Sn strand. Another advantage is that it can tolerate a longitudinal strain up to 0.55%. The RHQT Nb{sub 3}Al Rutherford cable will have less chance of contamination of the stabilizer, compared to Nb{sub 3}Sn cable. These characteristics of the RHQT Nb{sub 3}Al will be beneficial for designing and producing 15-Tesla dipole magnets. An example 15-Tesla magnet cross section, utilizing the RHQT Nb{sub 3}Sn strand is presented. A systematic investigation on RHQT Nb{sub 3}Al strands, its Rutherford cables, and building a small racetrack magnet for cable testing are proposed.

  17. 77 FR 60672 - Grant of Authority for Subzone Status; Tesla Motors, Inc., (Electric Passenger Vehicles), Palo...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ..., notice inviting public comment has been given in the Federal Register (77 FR 2269, 1-17-2012) and the... Foreign-Trade Zones Board Grant of Authority for Subzone Status; Tesla Motors, Inc., (Electric Passenger... establish a special-purpose subzone at the electric passenger vehicle manufacturing facilities of...

  18. Shot noise startup of the 6 nm SASE FEL at the TESLA test facility

    NASA Astrophysics Data System (ADS)

    Pierini, P.; Fawley, W. M.

    1996-02-01

    We present here the results of an extensive simulation activity for the TESLA SASE FEL. We have used the program GINGER to determine the FEL saturation length and the power fluctuations from shot to shot. The spectral properties of the output power and the correlation functions are investigated and compared with available theoretical models.

  19. Encouraging a "Romantic Understanding" of Science: The Effect of the Nikola Tesla Story

    ERIC Educational Resources Information Center

    Hadzigeorgiou, Yannis; Klassen, Stephen; Klassen, Cathrine Froese

    2012-01-01

    The purpose of this paper is to discuss and apply the notion of romantic understanding by outlining its features and its potential role in science education, to identify its features in the story of Nikola Tesla, and to describe an empirical study conducted to determine the effect of telling such a story to Grade 9 students. Elaborated features of…

  20. 7 tesla T2*-weighted MRI as a tool to improve detection of focal cortical dysplasia.

    PubMed

    Veersema, Tim J; van Eijsden, Pieter; Gosselaar, Peter H; Hendrikse, Jeroen; Zwanenburg, Jaco J M; Spliet, Wim G M; Aronica, Eleonora; Braun, Kees P J; Ferrier, Cyrille H

    2016-09-01

    Focal cortical dysplasia is one of the most common underlying pathologies in patients who undergo surgery for refractory epilepsy. Absence of a MRI-visible lesion necessitates additional diagnostic tests and is a predictor of poor surgical outcome. We describe a series of six patients with refractory epilepsy due to histopathologically-confirmed focal cortical dysplasia, for whom pre-surgical 7 tesla T2*-weighted MRI was acquired. In four of six patients, T2* sequences showed areas of marked superficial hypointensity, co-localizing with the epileptogenic lesion. 7 tesla T2* hypointensities overlying focal cortical dysplasia may represent leptomeningeal venous vascular abnormalities associated with the underlying dysplastic cortex. Adding T2* sequences to the MRI protocol may aid in the detection of focal cortical dysplasias.

  1. A high-field (30 Tesla) pulsed magnet instrument for single-crystal scattering studies

    NASA Astrophysics Data System (ADS)

    Islam, Zahirul; Nojiri, Hiroyuki; Narumi, Yasuo; Lang, Jonathan

    2010-03-01

    Pulsed magnets have emerged as a viable approach at synchrotron x-ray facilities for studying materials in high magnetic fields. We are developing a new high-field (30 Tesla) pulsed magnet system for single-crystal x-ray diffraction studies. It consists of a single 18mm-bore solenoid, designed and built at Tohoku University using high-tensile-strength and high conductivity CuAg wires. A dual-cryostat scheme has been developed at Advanced Photon Source in order to cool the coil using liquid nitrogen and the sample using a closed-cycle cryostat independently. Liquid nitrogen cooling allows repetition rate of a few minutes for peak fields near 30 Tesla. This scheme is unique in that it allows the applied magnetic field to be parallel to the scattering plane. Time-resolved scattering data are typically collected using a fast one-dimensional strip detector. Opportunities and challenges for experiments and instrumentation will be discussed.

  2. 7 tesla T2*-weighted MRI as a tool to improve detection of focal cortical dysplasia.

    PubMed

    Veersema, Tim J; van Eijsden, Pieter; Gosselaar, Peter H; Hendrikse, Jeroen; Zwanenburg, Jaco J M; Spliet, Wim G M; Aronica, Eleonora; Braun, Kees P J; Ferrier, Cyrille H

    2016-09-01

    Focal cortical dysplasia is one of the most common underlying pathologies in patients who undergo surgery for refractory epilepsy. Absence of a MRI-visible lesion necessitates additional diagnostic tests and is a predictor of poor surgical outcome. We describe a series of six patients with refractory epilepsy due to histopathologically-confirmed focal cortical dysplasia, for whom pre-surgical 7 tesla T2*-weighted MRI was acquired. In four of six patients, T2* sequences showed areas of marked superficial hypointensity, co-localizing with the epileptogenic lesion. 7 tesla T2* hypointensities overlying focal cortical dysplasia may represent leptomeningeal venous vascular abnormalities associated with the underlying dysplastic cortex. Adding T2* sequences to the MRI protocol may aid in the detection of focal cortical dysplasias. PMID:27435411

  3. Design study of steady-state 30-tesla liquid-neon-cooled magnet

    NASA Technical Reports Server (NTRS)

    Prok, G. M.; Brown, G. V.

    1976-01-01

    A design for a 30-tesla, liquid-neon-cooled magnet was reported which is capable of continuous operation. Cooled by nonboiling, forced-convection heat transfer to liquid neon flowing at 2.8 cu m/min in a closed, pressurized heat-transfer loop and structurally supported by a tapered structural ribbon, the tape-wound coils with a high-purity-aluminum conductor will produce over 30 teslas for 1 minute at 850 kilowatts. The magnet will have an inside diameter of 7.5 centimeters and an outside diameter of 54 centimeters. The minimum current density at design field will be 15.7 kA/sq cm.

  4. A modified post damping ring bunch compressor beamline for the TESLA linear collider

    SciTech Connect

    Philippe R.-G. Piot; Winfried Decking

    2004-03-23

    We propose a modified bunch compressor beamline, downstream of the damping ring, for the TESLA linear collider. This modified beamline uses a third harmonic radio-frequency section based on the 3.9 GHz superconducting cavity under development at Fermilab. In our design the beam deceleration is about {approx}50 MeV instead of {approx}450 MeV in the original design proposed.

  5. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    NASA Astrophysics Data System (ADS)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-01

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  6. A Tesla-type repetitive nanosecond pulse generator for solid dielectric breakdown research

    NASA Astrophysics Data System (ADS)

    Zhao, Liang; Pan, Ya Feng; Su, Jian Cang; Zhang, Xi Bo; Wang, Li Min; Fang, Jin Peng; Sun, Xu; Lui, Rui

    2013-10-01

    A Tesla-type repetitive nanosecond pulse generator including a pair of electrode and a matched absorption resistor is established for the application of solid dielectric breakdown research. As major components, a built-in Tesla transformer and a gas-gap switch are designed to boost and shape the output pulse, respectively; the electrode is to form the anticipated electric field; the resistor is parallel to the electrode to absorb the reflected energy from the test sample. The parameters of the generator are a pulse width of 10 ns, a rise and fall time of 3 ns, and a maximum amplitude of 300 kV. By modifying the primary circuit of the Tesla transformer, the generator can produce both positive and negative pulses at a repetition rate of 1-50 Hz. In addition, a real-time measurement and control system is established based on the solid dielectric breakdown requirements for this generator. With this system, experiments on test samples made of common insulation materials in pulsed power systems are conducted. The preliminary experimental results show that the constructed generator is capable to research the solid dielectric breakdown phenomenon on a nanosecond time scale.

  7. Assessment of MRI Issues at 3 Tesla for a New Metallic Tissue Marker.

    PubMed

    Cronenweth, Charlotte M; Shellock, Frank G

    2015-01-01

    Purpose. To assess the MRI issues at 3 Tesla for a metallic tissue marker used to localize removal areas of tissue abnormalities. Materials and Methods. A newly designed, metallic tissue marker (Achieve Marker, CareFusion, Vernon Hills, IL) used to mark biopsy sites, particularly in breasts, was assessed for MRI issues which included standardized tests to determine magnetic field interactions (i.e., translational attraction and torque), MRI-related heating, and artifacts at 3 Tesla. Temperature changes were determined for the marker using a gelled-saline-filled phantom. MRI was performed at a relatively high specific absorption rate (whole body averaged SAR, 2.9-W/kg). MRI artifacts were evaluated using T1-weighted, spin echo and gradient echo pulse sequences. Results. The marker displayed minimal magnetic field interactions (2-degree deflection angle and no torque). MRI-related heating was only 0.1°C above background heating (i.e., the heating without the tissue marker present). Artifacts seen as localized signal loss were relatively small in relation to the size and shape of the marker. Conclusions. Based on the findings, the new metallic tissue marker is acceptable or "MR Conditional" (using current labeling terminology) for a patient undergoing an MRI procedure at 3 Tesla or less.

  8. 7-Tesla MRI demonstrates absence of structural lesions in patients with vestibular paroxysmia.

    PubMed

    Rommer, Paulus S; Wiest, Gerald; Kronnerwetter, Claudia; Zach, Heidemarie; Loader, Benjamin; Elwischger, Kirsten; Trattnig, Siegfried

    2015-01-01

    Vestibular parxoysmia (VP) is a rare vestibular disorder. A neurovascular cross-compression (NVCC) between the vestibulochochlear nerve and an artery seems to be responsible for short attacks of vertigo in this entity. An NVCC can be seen in up to every fourth subject. The significance of these findings is not clear, as not all subjects suffer from symptoms. The aim of the present study was to assess possible structural lesions of the vestibulocochlear nerve by means of high field magnetic resonance imaging (MRI), and whether high field MRI may help to differentiate symptomatic from asymptomatic subjects. 7 Tesla MRI was performed in six patients with VP and confirmed NVCC seen on 1.5 and 3.0 MRI. No structural abnormalities were detected in any of the patients in 7 Tesla MRI. These findings imply that high field MRI does not help to differentiate between symptomatic and asymptomatic NVCC and that the symptoms of VP are not caused by structural nerve lesions. This supports the hypothesis that the nystagmus associated with VP has to be conceived pathophysiologically as an excitatory vestibular phenomenon, being not related to vestibular hypofunction. 7 Tesla MRI outperforms conventional MRI in image resolution and may be useful in vestibular disorders.

  9. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

    PubMed

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-01

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  10. Construction of TAMU3: A 14 Tesla Nb3Sn Model Dipole

    NASA Astrophysics Data System (ADS)

    Holik, Eddie; Blackburn, Raymond; Diaczenko, Nick; Elliott, Tim; Jaisle, Andrew; McInturff, Alfred; McIntyre, Peter; Sattarov, Dior

    2010-10-01

    The third phase of the Texas A&M University Accelerator Research Lab's ``Stress-Managed'' high field magnet campaign has coil modules for the assembly of TAMU3. The third phase is the high field, Bmax >= 12 -- 14 Tesla, proof of principle test of the ``Stress-Managed'' coil fabrication design philosophy. Earlier dipole phases operated in the 5 -- 8 Tesla range using NbTi and early bronze (ITER) Nb3Sn based superconductor. These third phase dipole winding modules use the tin rich multi-filament Nb3Sn/Cu composite strand with its enhanced engineering current density therefore have the possibility of producing magnetic fields > 14 Tesla, when combined with the evolution of much higher efficiency insulation. There are five modules under construction altogether, which are at various stages. The best performing pair during testing of these modules will comprise the upper and lower modules of TAMU4, a 4x2 cm aperture accelerator prototype dipole. There has also been progress in the fabrication and measurement techniques necessary to validate more accurately the ``Stress-Management'' approach.

  11. Focused tight dressing does not prevent cochlear implant magnet migration under 1.5 Tesla MRI.

    PubMed

    Cuda, D; Murri, A; Succo, G

    2013-04-01

    We report a retrospective case of inner magnet migration, which occurred after 1.5 Tesla MRI scanning in an adult recipient of a bilateral cochlear implant (CI) despite a focused head dressing. The patient, bilaterally implanted with Nucleus 5 CIs (Cochlear LTD, Sydney, Australia), underwent a 1.5 Tesla cholangio-MRI scan for biliary duct pathology. In subsequent days, a focal skin alteration appeared over the left inner coil. Plain skull radiographs showed partial magnet migration on the left side. Surgical exploration confirmed magnet twisting; the magnet was effectively repositioned. Left CI performance was restored to pre-migration level. The wound healed without complications. Thus, focused dressing does not prevent magnet migration in CI recipients undergoing 1.5 Tesla MRI. All patients should be counselled on this potential complication. A minor surgical procedure is required to reposition the magnet. Nevertheless, timely diagnosis is necessary to prevent skin breakdown and subsequent device contamination. Plain skull radiograph is very effective in identifying magnet twisting; it should be performed systematically after MRI or minimally on all suspected cases.

  12. Assessment of MRI Issues at 3 Tesla for a New Metallic Tissue Marker

    PubMed Central

    Cronenweth, Charlotte M.; Shellock, Frank G.

    2015-01-01

    Purpose. To assess the MRI issues at 3 Tesla for a metallic tissue marker used to localize removal areas of tissue abnormalities. Materials and Methods. A newly designed, metallic tissue marker (Achieve Marker, CareFusion, Vernon Hills, IL) used to mark biopsy sites, particularly in breasts, was assessed for MRI issues which included standardized tests to determine magnetic field interactions (i.e., translational attraction and torque), MRI-related heating, and artifacts at 3 Tesla. Temperature changes were determined for the marker using a gelled-saline-filled phantom. MRI was performed at a relatively high specific absorption rate (whole body averaged SAR, 2.9-W/kg). MRI artifacts were evaluated using T1-weighted, spin echo and gradient echo pulse sequences. Results. The marker displayed minimal magnetic field interactions (2-degree deflection angle and no torque). MRI-related heating was only 0.1°C above background heating (i.e., the heating without the tissue marker present). Artifacts seen as localized signal loss were relatively small in relation to the size and shape of the marker. Conclusions. Based on the findings, the new metallic tissue marker is acceptable or “MR Conditional” (using current labeling terminology) for a patient undergoing an MRI procedure at 3 Tesla or less. PMID:26266051

  13. A Tesla-type repetitive nanosecond pulse generator for solid dielectric breakdown research.

    PubMed

    Zhao, Liang; Pan, Ya Feng; Su, Jian Cang; Zhang, Xi Bo; Wang, Li Min; Fang, Jin Peng; Sun, Xu; Lui, Rui

    2013-10-01

    A Tesla-type repetitive nanosecond pulse generator including a pair of electrode and a matched absorption resistor is established for the application of solid dielectric breakdown research. As major components, a built-in Tesla transformer and a gas-gap switch are designed to boost and shape the output pulse, respectively; the electrode is to form the anticipated electric field; the resistor is parallel to the electrode to absorb the reflected energy from the test sample. The parameters of the generator are a pulse width of 10 ns, a rise and fall time of 3 ns, and a maximum amplitude of 300 kV. By modifying the primary circuit of the Tesla transformer, the generator can produce both positive and negative pulses at a repetition rate of 1-50 Hz. In addition, a real-time measurement and control system is established based on the solid dielectric breakdown requirements for this generator. With this system, experiments on test samples made of common insulation materials in pulsed power systems are conducted. The preliminary experimental results show that the constructed generator is capable to research the solid dielectric breakdown phenomenon on a nanosecond time scale.

  14. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    SciTech Connect

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-15

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  15. Incidental optochiasmatic cavernoma: Case report of an unusual finding on 3 Tesla MRI.

    PubMed

    Trentadue, Mirko; Pozzi Mucelli, Roberto; Piovan, Enrico; Pizzini, Francesca Benedetta

    2016-08-01

    Cavernoma is a vascular hamartoma, which represents 10-20% of all central nervous system vascular malformations. The majority (80%) of them are supratentorial, while involvement of the cranial nerves and the optic pathways is extremely rare. The main clinical presentation of optochiasmatic cavernomas consists of chiasmatic apoplexy, which is a neurosurgical emergency. Here, we report a case in which the finding was incidentally detected in a 49-year-old man. We describe the imaging characteristics of the lesion in such a rare location, highlighting the role of magnetic resonance imaging (MRI) (specifically 3 Tesla) in the management of asymptomatic patients.

  16. Science and Technology of the TESLA Electron-Positron Linear Collider

    NASA Astrophysics Data System (ADS)

    Wagner, Albrecht

    2002-07-01

    Recent analyses of the long term future of particles physics in Asia, Europe, and the U.S.A. have led to the consensus that the next major facility to be built to unravel the secrets of the micro-cosmos is an electron-positron linear collider in the energy range of 500 to 1000 GeV. This collider should be constructed in an as timely fashion as possible to overlap with the Large Hadron Collider, under construction at CERN. Here, the scientific potential and the technological aspects of the TESLA projects, a superconducting collider with an integrated X-ray laser laboratory, are summarised.

  17. Comparison of the TESLA, NLC and CLIC beam-collimation system performance

    SciTech Connect

    Alexandr I Drozhdin; Grahame Blair; Lewis P Keller

    2003-05-28

    This report describes studies performed in the framework of the Collimation Task Force organized to support the work of the International Linear Collider Technical Review Committee. The post-linac beam-collimation systems in the TESLA, JLC/NLC and CLIC linear-collider designs are compared using the same computer code under the same assumptions. Their performance is quantified in terms of beam-halo and synchrotron-radiation collimation efficiency. The performance of the current designs varies across projects, and does not always meet the original design goals. But these comparisons suggest that achieving the required performance in a future linear collider is feasible.

  18. 3.0 Tesla magnetic resonance imaging: A new standard in liver imaging?

    PubMed

    Girometti, Rossano

    2015-07-28

    An ever-increasing number of 3.0 Tesla (T) magnets are installed worldwide. Moving from the standard of 1.5 T to higher field strength implies a number of potential advantage and drawbacks, requiring careful optimization of imaging protocols or implementation of novel hardware components. Clinical practice and literature review suggest that state-of-the-art 3.0 T is equivalent to 1.5 T in the assessment of focal liver lesions and diffuse liver disease. Therefore, further technical improvements are needed in order to fully exploit the potential of higher field strength.

  19. Large scale Tesla coil guided discharges initiated by femtosecond laser filamentation in air

    NASA Astrophysics Data System (ADS)

    Arantchouk, L.; Point, G.; Brelet, Y.; Prade, B.; Carbonnel, J.; André, Y.-B.; Mysyrowicz, A.; Houard, A.

    2014-07-01

    The guiding of meter scale electric discharges produced in air by a Tesla coil is realized in laboratory using a focused terawatt laser pulse undergoing filamentation. The influence of the focus position, the laser arrival time, or the gap length is studied to determine the best conditions for efficient laser guiding. Discharge parameters such as delay, jitter, and resistance are characterized. An increase of the discharge length by a factor 5 has been achieved with the laser filaments, corresponding to a mean breakdown field of 2 kV/cm for a 1.8 m gap length. Consecutive guided discharges at a repetition rate of 10 Hz are also reported.

  20. Tesla: An application for real-time data analysis in High Energy Physics

    NASA Astrophysics Data System (ADS)

    Aaij, R.; Amato, S.; Anderlini, L.; Benson, S.; Cattaneo, M.; Clemencic, M.; Couturier, B.; Frank, M.; Gligorov, V. V.; Head, T.; Jones, C.; Komarov, I.; Lupton, O.; Matev, R.; Raven, G.; Sciascia, B.; Skwarnicki, T.; Spradlin, P.; Stahl, S.; Storaci, B.; Vesterinen, M.

    2016-11-01

    Upgrades to the LHCb computing infrastructure in the first long shutdown of the LHC have allowed for high quality decay information to be calculated by the software trigger making a separate offline event reconstruction unnecessary. Furthermore, the storage space of the triggered candidate is an order of magnitude smaller than the entire raw event that would otherwise need to be persisted. Tesla is an application designed to process the information calculated by the trigger, with the resulting output used to directly perform physics measurements.

  1. Cavity control system advanced modeling and simulations for TESLA linear accelerator and free electron laser

    NASA Astrophysics Data System (ADS)

    Czarski, Tomasz; Romaniuk, Ryszard S.; Pozniak, Krzysztof T.; Simrock, Stefan

    2004-07-01

    The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced. The elementary analysis of the cavity resonator on RF (radio frequency) level and low level frequency with signal and power considerations is presented. For the field vector detection the digital signal processing is proposed. The electromechanical model concerning Lorentz force detuning is applied for analyzing the basic features of the system performance. For multiple cavities driven by one klystron the field vector sum control is considered. Simulink model implementation is developed to explore the feedback and feed-forward system operation and some experimental results for signals and power considerations are presented.

  2. Liquid neon heat transfer as applied to a 30 tesla cryomagnet

    NASA Technical Reports Server (NTRS)

    Papell, S. S.; Hendricks, R. C.

    1975-01-01

    A 30-tesla magnet design is studied which calls for forced convection liquid neon heat transfer in small coolant channels. The design also requires suppressing boiling by subjecting the fluid to high pressures through use of magnet coils enclosed in a pressure vessel which is maintained at the critical pressure of liquid neon. This high pressure reduces the possibility of the system flow instabilities which may occur at low pressures. The forced convection heat transfer data presented were obtained by using a blowdown technique to force the fluid to flow vertically through a resistance heated, instrumented tube.

  3. Poly-coil design for a 60 tesla quasi-stationary magnet

    SciTech Connect

    Boenig, H.J.; Campbell, L.J.; Hodgdon, M.L.; Lopez, E.A.; Rickel, D.G.; Rogers, J.D.; Schillig, J.B.; Sims, J.R. ); Pernambuco-Wise, P.; Schneider-Muntau, H.J.; Van Bockstal, L. . National High Magnetic Field Lab.)

    1993-01-01

    Among the new facilities to be offered by the National Science Foundation through the National High Magnetic Field Laboratory (NHMFL) are pulsed fields that can only be achieved at a national user facility by virtue of their strength, duration, and volume. In particular, a 44 mm bore pulsed magnet giving a 60 tesla field for 1 00 ms is in the final design stage. This magnet will be powered by a 1.4 GW motor-generator at Los Alamos and is an important step toward proving design principles that will be needed for the higher field quasi-stationary pulsed magnets that this power source is capable of driving.

  4. Poly-coil design for a 60 tesla quasi-stationary magnet

    NASA Astrophysics Data System (ADS)

    Boenig, H. J.; Campbell, L. J.; Hodgdon, M. L.; Lopez, E. A.; Rickel, D. G.; Rogers, J. D.; Schillig, J. B.; Sims, J. R.; Pernambuco-Wise, P.; Schneider-Muntau, H. J.

    1993-02-01

    Among the new facilities to be offered by the National Science Foundation through the National High Magnetic Field Laboratory (NHMFL) are pulsed fields that can only be achieved at a national user facility by virtue of their strength, duration, and volume. In particular, a 44 mm bore pulsed magnet giving a 60 tesla field for 100 ms is in the final design stage. This magnet will be powered by a 1.4 GW motor-generator at Los Alamos and is an important step toward proving design principles that will be needed for the higher field quasi-stationary pulsed magnets that this power source is capable of driving.

  5. Poly-coil design for a 60 tesla quasi-stationary magnet

    SciTech Connect

    Boenig, H.J.; Campbell, L.J.; Hodgdon, M.L.; Lopez, E.A.; Rickel, D.G.; Rogers, J.D.; Schillig, J.B.; Sims, J.R.; Pernambuco-Wise, P.; Schneider-Muntau, H.J.; Van Bockstal, L.

    1993-02-01

    Among the new facilities to be offered by the National Science Foundation through the National High Magnetic Field Laboratory (NHMFL) are pulsed fields that can only be achieved at a national user facility by virtue of their strength, duration, and volume. In particular, a 44 mm bore pulsed magnet giving a 60 tesla field for 1 00 ms is in the final design stage. This magnet will be powered by a 1.4 GW motor-generator at Los Alamos and is an important step toward proving design principles that will be needed for the higher field quasi-stationary pulsed magnets that this power source is capable of driving.

  6. In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla.

    PubMed

    Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

    2015-03-01

    Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

  7. Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

    SciTech Connect

    Bane, K.L.F.; Adolphsen, C.; Li, Z.; Dohlus, M.; Zagorodnov, I.; Gonin, I.; Lunin, A.; Solyak, N.; Yakovlev, V.; Gjonaj, E.; Weiland, T.; /Darmstadt, Tech. Hochsch.

    2008-07-07

    In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm.

  8. In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

    NASA Astrophysics Data System (ADS)

    Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

    2015-03-01

    Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1-) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

  9. Encouraging a "Romantic Understanding" of Science: The Effect of the Nikola Tesla Story

    NASA Astrophysics Data System (ADS)

    Hadzigeorgiou, Yannis; Klassen, Stephen; Klassen, Cathrine Froese

    2012-08-01

    The purpose of this paper is to discuss and apply the notion of romantic understanding by outlining its features and its potential role in science education, to identify its features in the story of Nikola Tesla, and to describe an empirical study conducted to determine the effect of telling such a story to Grade 9 students. Elaborated features of the story are the humanization of meaning, an association with heroes and heroic qualities, the limits of reality and extremes of experience, a sense of wonder, and a contesting of conventions and conventional ideas. The study demonstrates the learning benefits of encouraging a romantic understanding through a story that is structured explicitly around the identified features, in this instance in the context of the production and transmission of alternating current electricity. Quantitative and qualitative analyses of journal entries showed that the group of students who were encouraged to understand the concept of alternating current romantically (the experimental group) became more involved with both the content and the context of the story than a comparison group of students who were taught the concept explicitly, without a context (the control group). The students in the experimental group also performed statistically better on a science-content test taken 1 week and again 8 weeks after the indicated teaching intervention. This finding, along with the content analyses of students' journals, provided evidence of romantic understanding of the science content for those students who listened to the Tesla story.

  10. Non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses: comparison at 1.5 Tesla and 3 Tesla

    PubMed Central

    Isoda, Hiroyoshi; Furuta, Akihiro; Togashi, Kaori

    2015-01-01

    Background A 3 Tesla (3 T) magnetic resonance (MR) scanner is a promising tool for upper abdominal MR angiography. However, there is no report focused on the image quality of non-contrast-enhanced MR portography and hepatic venography at 3 T. Purpose To compare and evaluate images of non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses (Time-SLIP) at 1.5 Tesla (1.5 T) and 3 T. Material and Methods Twenty-five healthy volunteers were examined using respiratory-triggered three-dimensional balanced steady-state free-precession (bSSFP) with Time-SLIP. For portography, we used one tagging pulse (selective inversion recovery) and one non-selective inversion recovery pulse; for venography, two tagging pulses were used. The relative signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantified, and the quality of visualization was evaluated. Results The CNRs of the main portal vein, right portal vein, and left portal vein at 3 T were better than at 1.5 T. The image quality scores for the portal branches of segment 4, 5, and 8 were significantly higher at 3 T than at 1.5 T. The CNR of the right hepatic vein (RHV) at 3 T was significantly lower than at 1.5 T. The image quality scores of RHV and the middle hepatic vein were higher at 1.5 T than at 3 T. For RHV visualization, the difference was statistically significant. Conclusion Non-contrast-enhanced MR portography with Time-SLIP at 3 T significantly improved visualization of the peripheral branch in healthy volunteers compared with1.5 T. Non-contrast-enhanced MR hepatic venography at 1.5 T was better than at 3 T. PMID:26019890

  11. Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

    SciTech Connect

    Pflueger, J.; Nikitina, Y.M.

    1995-12-31

    For the VUV-FEL at the TESLA Test Facility an undulator with a total length of 30 m is needed. In this study three different approaches to realize an undulator with a sinusoidal plus a superimposed quadrupolar field were studied with the 3D code MAFIA.

  12. Inter-speaker speech variability assessment using statistical deformable models from 3.0 tesla magnetic resonance images.

    PubMed

    Vasconcelos, Maria J M; Ventura, Sandra M R; Freitas, Diamantino R S; Tavares, João Manuel R S

    2012-03-01

    The morphological and dynamic characterisation of the vocal tract during speech production has been gaining greater attention due to the motivation of the latest improvements in magnetic resonance (MR) imaging; namely, with the use of higher magnetic fields, such as 3.0 Tesla. In this work, the automatic study of the vocal tract from 3.0 Tesla MR images was assessed through the application of statistical deformable models. Therefore, the primary goal focused on the analysis of the shape of the vocal tract during the articulation of European Portuguese sounds, followed by the evaluation of the results concerning the automatic segmentation, i.e. identification of the vocal tract in new MR images. In what concerns speech production, this is the first attempt to automatically characterise and reconstruct the vocal tract shape of 3.0 Tesla MR images by using deformable models; particularly, by using active and appearance shape models. The achieved results clearly evidence the adequacy and advantage of the automatic analysis of the 3.0 Tesla MR images of these deformable models in order to extract the vocal tract shape and assess the involved articulatory movements. These achievements are mostly required, for example, for a better knowledge of speech production, mainly of patients suffering from articulatory disorders, and to build enhanced speech synthesizer models.

  13. Does Magnetic Resonance Brain Scanning at 3.0 Tesla Pose a Hyperthermic Challenge to Term Neonates?

    PubMed

    Cawley, Paul; Few, Karen; Greenwood, Richard; Malcolm, Paul; Johnson, Glyn; Lally, Pete; Thayyil, Sudhin; Clarke, Paul

    2016-08-01

    Next-generation 3-Tesla magnetic resonance (MR) scanners offer improved neonatal neuroimaging, but the greater associated radiofrequency radiation may increase the risk of hyperthermia. Safety data for neonatal 3-T MR scanning are lacking. We measured rectal temperatures continuously in 25 neonates undergoing 3-T brain MR imaging and observed no significant hyperthermic threat.

  14. Design considerations and analysis of potential applications of a high power ultraviolet FEL at the TESLA test facility at DESY

    NASA Astrophysics Data System (ADS)

    Pagani, C.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    1999-02-01

    A possibility of constructing a high power ultraviolet free electron laser at the TESLA test facility at DESY is discussed. The proposed facility consists of a tunable master oscillator (P av˜10 mW, P peak˜10 kW, λ≃200-350 nm) and an FEL amplifier with a tapered undulator. The average and peak radiation power at the exit of the FEL amplifier is about 7 kW and 220 GW, respectively. Installation of such a facility can significantly extend scientific potential of the TESLA test facility. The UV free electron laser can be used to construct a polarized, monochromatic gamma-source with the ultimate yield up to 10 12 gamma-quanta per second and the maximal energy of about 100 MeV. An intensive gamma-source can also form the base for constructing the test facility for the TESLA positron generation system. Another accelerator application of the proposed facility is verification of the main technical solutions for the laser and the optical system to be used in the gamma-gamma option of the TESLA collider. A high average power UV laser is also promising for industrial applications.

  15. 76 FR 60118 - Tesla Motors, Inc. Grant of Petition for Renewal of a Temporary Exemption From the Advanced Air...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    .... (Tesla) for the renewal of a temporary exemption of its Roadster model from the advanced air bag... substantial economic hardship to a manufacturer that has tried to comply with the standard in good faith... risks presented by air bag deployment. \\3\\ See 65 FR 30680 (May 12, 2000). The issuance of the...

  16. 77 FR 2269 - Foreign-Trade Zone 18-San Jose, CA, Application for Subzone, Tesla Motors, Inc. (Electric...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 18--San Jose, CA, Application for Subzone, Tesla Motors, Inc...-Trade Zones Board (the Board) by the City of San Jose, California, grantee of FTZ 18, requesting...

  17. Human in vivo cardiac phosphorus NMR spectroscopy at 3.0 Tesla

    NASA Astrophysics Data System (ADS)

    Bruner, Angela Properzio

    One of the newest methods with great potential for use in clinical diagnosis of heart disease is human, cardiac, phosphorus NMR spectroscopy (cardiac p 31 MRS). Cardiac p31 MRS is able to provide quantitative, non-invasive, functional information about the myocardial energy metabolites such as pH, phosphocreatine (PCr), and adenosinetriphosphate (ATP). In addition to the use of cardiac p3l MRS for other types of cardiac problems, studies have shown that the ratio of PCr/ATP and pH are sensitive and specific markers of ischemia at the myocardial level. In human studies, typically performed at 1.5 Tesla, PCr/ATP has been relatively easy to measure but often requires long scan times to provide adequate signal-to-noise (SNR). In addition, pH which relies on identification of inorganic phosphate (Pi), has rarely been obtained. Significant improvement in the quality of cardiac p31 MRS was achieved through the use of the General Electric SIGNATM 3.0 Tesla whole body magnet, improved coil designs and optimized pulse sequences. Phantom and human studies performed on many types of imaging and spectroscopy sequences, identified breathhold gradient-echo imaging and oblique DRESS p31 spectroscopy as the best compromises between SNR, flexibility and quality localization. Both single-turn and quadrature 10-cm diameter, p31 radiofrequency coils, were tested with the quadrature coil providing greater SNR, but at a greater depth to avoid skeletal muscle contamination. Cardiac p31 MRS obtained in just 6 to 8 minutes, gated, showed both improved SNR and discernment of Pi allowing for pH measurement. A handgrip, in-magnet exerciser was designed, created and tested at 1.5 and 3.0 Tesla on volunteers and patients. In ischemic patients, this exercise was adequate to cause a repeated drop in PCr/ATP and pH with approximately eight minutes of isometric exercise at 30% maximum effort. As expected from literature, this exercise did not cause a drop in PCr/ATP for reference volunteers.

  18. Parameter study of the VUV-FEL at the Tesla Test Facility

    SciTech Connect

    Brefeld, W.; Faatz, B.

    1995-12-31

    In this contribution we present a detailed study of the influence of the electron beam and machine parameters on the performance of the TTF VUV FEL, which is in its design stage at DESY. The TTF FEL will be a 6 nm SASE device operating with the beam provided by the Tesla Test Facility superconducting linac, driven by an rf photcathode gun. The FEL output power and saturation length have been assessed with the use of different 2D3-D steady state simulation codes. The parameter range over which the FEL would reach saturation within the specified undulator length of 25 to 30 m have been determined and checked against semi-analytical expressions.

  19. Shot noise startup of the 6 NM SASE FEL at the Tesla Test Facility

    SciTech Connect

    Pierini, P.; Fawley, W.M.

    1995-12-31

    We present here an analysis of the shot noise startup of the 6 nm SASE FEI proposal at the TESLA Test Facility in DESY The statistical of the saturation length and output power due to the intrinsic randomness of the noise startup are investigated with the use of the 2D time dependent code GINGER, that takes into account propagation effects and models shot noise. We then provide estimates for the spectral contents and linewidth of the emitted radiation and describe its spiking characteristics. The output radiation will develop superradiant spikes seeded by the shot noise in the electron beam, which can entrance the average emitted power at the expense of some spectral broadening.

  20. Preattentive mechanisms of change detection in early auditory cortex: a 7 Tesla fMRI study.

    PubMed

    Szycik, G R; Stadler, J; Brechmann, A; Münte, T F

    2013-12-01

    The auditory system continuously monitors the environment for irregularities in an automatic, preattentive fashion. This is presumably accomplished by two mechanisms: a sensory mechanism detects a deviant sound on the basis of differential refractoriness of neural populations sensitive to the standard and deviant sounds, whereas the cognitive mechanism reveals deviance by comparing incoming auditory information with a template derived from previous input. Using fast event-related high-resolution functional magnetic resonance imaging at 7 Tesla we show that both mechanisms can be mapped to different parts of the auditory cortex both at the group level and the single-subject level. The sensory mechanism is supported by primary auditory areas in Heschl's gyrus whereas the cognitive mechanism is implemented in more anterior secondary auditory areas. Both mechanisms are equally engaged by simple sine-wave tones and speech-related phonemes indicating that streams of speech and non-speech stimuli are processed in a similar fashion. PMID:23994180

  1. Anatomy and metabolism of the normal human brain studied by magnetic resonance at 1. 5 Tesla

    SciTech Connect

    Bottomley, P.A.; Hart, H.R. Jr.; Edelstein, W.A.; Schenck, J.F.; Smith, L.S.; Leue, W.M.; Mueller, O.M.; Redington, R.W.

    1984-02-01

    Proton magnetic resonance (MR) images were obtained of the human head in magnetic fields as high as 1.5 Tesla (T) using slotted resonator high radio-frequency (RF) detection coils. The images showed no RF field penetration problems and exhibited an 11 (+/-1)-fold improvement in signal-to-noise ratio over a .12-T imaging system. The first localized phosphorus 31, carbon 13, and proton MR chemical shift spectra recorded with surface coils from the head and body in the same instrument showed relative concentrations of phosphorus metabolites, triglycerides, and, when correlated with proton images, negligible lipid (-CH/sub 2/-) signal from brain tissue on the time scale of the imaging experiment. Sugar phosphate and phosphodiester concentrations were significantly elevated in the head compared with muscle. This method should allow the combined assessment of anatomy, metabolism, and biochemistry in both the normal and diseased brain.

  2. Fabrication and characterization of a MEMS nano-Tesla ferromagnetic-piezoelectric magnetic sensor array

    NASA Astrophysics Data System (ADS)

    Qu, Peng; Gollapudi, Sreenivasulu; Bidthanapally, Rao; Srinivasan, Gopalan; Petrov, Vladimir; Qu, Hongwei

    2016-06-01

    A self-biased MEMS magnetic sensor array with ferromagnetic-piezoelectric composites has been fabricated and characterized. The array with two Quartz-Nickel-Metglas cantilevers with nano-tesla sensitivity was fabricated by MEMS processes including silicon-quartz low temperature bonding, quartz wafer thinning, and electroplating of thick nickel thin films. Under self-biasing due to magnetization grading of ferromagnetic layer, magnetoelectric coefficients of 6.6 and 5.6 V/cm Oe and resolutions of ˜0.58 and ˜0.75 nT are obtained at the mechanical resonant frequencies of 191.5 and 184.8 Hz for the two sensors in the array, respectively. Such arrays have the potential for applications in biomagnetic imaging technologies including magneto-cardiography.

  3. Magnet Design and Analysis of a 40 Tesla Long Pulse System Energized by a Battery Bank

    NASA Astrophysics Data System (ADS)

    Lv, Y. L.; Peng, T.; Wang, G. B.; Ding, T. H.; Han, X. T.; Pan, Y.; Li, L.

    2013-03-01

    A 40 tesla long pulse magnet and a battery bank as the power supply have been designed. This is now under construction at the Wuhan National High Magnetic Field Center. The 22 mm bore magnet will generate smooth pulses with duration 1 s and rise time 0.5 s. The battery bank consists of 945 12V/200 Ah lead-acid battery cells. The magnet and battery bank were optimized by codes developed in-house and by ANSYS. The coil was made from soft copper with internal reinforcement by fiber-epoxy composite; it is divided into two sections connected in series. The inner section consists of helix coils with each layer reinforced by Zylon composite. The outer section will be wound from copper sheet and externally reinforced by carbon fiber composite.

  4. Current Progress in Fabrication of a 14 Tesla Nb3Sn Dipole

    NASA Astrophysics Data System (ADS)

    Holik, Eddie, III; Benson, Christopher; Damborsky, Kyle; Diaczenko, Nick; Elliott, Tim; Garrison, Ray; Jaisle, Andrew; McInturff, Alfred; McIntyre, Peter; Sattarov, Dior

    2012-03-01

    The Accelerator Technology Laboratory at Texas A&M is fabricating a model dipole magnet, TAMU3, designed to operate at a 14 Tesla bore field. The dipole employs an advanced internal-tin Nb3Sn/Cu composite strand with enhanced current density. The coils must be processed through a heat treatment after winding, during which the Sn within the heterogeneous strands diffuse into the Cu/Nb matrix to form high-performance superconducting layers. Heat treatment of the first coil assembly revealed tin leakage from the Sn cores that was caused by omission of a pre-anneal step in the heat treatment. We are evaluating the electrical properties of the coil, the microstructure and short-sample superconducting performance of cut-off samples of current leads to determine the extent of damage to the performance of the windings. Results of those tests and plans for construction of TAMU3 will be presented.

  5. Light scattering from liquid crystal director fluctuations in steady magnetic fields up to 25 tesla

    NASA Astrophysics Data System (ADS)

    Challa, Pavan K.; Curtiss, O.; Williams, J. C.; Twieg, R.; Toth, J.; McGill, S.; Jákli, A.; Gleeson, J. T.; Sprunt, S. N.

    2012-07-01

    We report on homodyne dynamic light scattering measurements of orientational fluctuation modes in both calamitic and bent-core nematic liquid crystals, carried out in the new split-helix resistive magnet at the National High Magnetic Field Laboratory. The relaxation rate and inverse scattered intensity of director fluctuations exhibit a linear dependence on field-squared up to 25 tesla, which is consistent with strictly lowest order coupling of the tensor order parameter Q to field (QαβBαBβ) in the nematic free energy. However, we also observe evidence of field dependence of certain nematic material parameters, an effect which may be expected from the mean field scaling of these quantities with the magnitude of Q and the predicted variation of Q with field.

  6. Light scattering from liquid crystal director fluctuations in steady magnetic fields up to 25 tesla.

    PubMed

    Challa, Pavan K; Curtiss, O; Williams, J C; Twieg, R; Toth, J; McGill, S; Jákli, A; Gleeson, J T; Sprunt, S N

    2012-07-01

    We report on homodyne dynamic light scattering measurements of orientational fluctuation modes in both calamitic and bent-core nematic liquid crystals, carried out in the new split-helix resistive magnet at the National High Magnetic Field Laboratory. The relaxation rate and inverse scattered intensity of director fluctuations exhibit a linear dependence on field-squared up to 25 tesla, which is consistent with strictly lowest order coupling of the tensor order parameter Q to field (Q(αβ)B(α)B(β)) in the nematic free energy. However, we also observe evidence of field dependence of certain nematic material parameters, an effect which may be expected from the mean field scaling of these quantities with the magnitude of Q and the predicted variation of Q with field. PMID:23005438

  7. Undulator system for the VUV FEL at the TESLA test facility phase-2

    NASA Astrophysics Data System (ADS)

    Pflüger, J.; Hahn, U.; Faatz, B.; Tischer, M.

    2003-07-01

    The Phase-1 of the VUV Free Electron Laser at the TESLA Test Facility finishes in fall 2002. Phase-2, an extension of Phase-1 towards shorter wavelengths is under construction and will be ready for operation in 2003. A radiation wavelength as low as 6 nm will be obtained by raising the electron energy to 1 GeV. There will be only minor changes to the undulator system. Compared to Phase-1, six instead of three undulator segments will be installed. The integrated focusing system will be replaced by an electromagnetic doublet structure. We report about the changes of the undulator, the undulator vacuum system, the separated quadrupoles including a stretched wire alignment systems and the modifications to the beam diagnostic system consisting of pick up monitors and wire scanners.

  8. A VUV free electron laser at the TESLA test facility at DESY

    NASA Astrophysics Data System (ADS)

    Rossbach, J.; Tesla Fel Study Group

    1996-02-01

    We present the layout of a single pass free electron laser (FEL) to be driven by the TESLA Test Facility (TTF) currently under construction at DESY. The TTF is a test-bed for high-gradient, high efficiency superconducting acceleration sections for a future linear collider. Due to its unrivaled ability to sustain high beam quality during acceleration, a superconducting rf linac is considered the optimum choice to drive a FEL. We aim at a photon wavelength of λ = 6 nm utilizing the TTF after it has been extended to 1 GeV beam energy. Due to lack of mirrors and seed-lasers in this wavelength regime, a single pass FEL and self-amplified spontaneous emission (SASE) is considered. A first test is foreseen at a larger photon wavelength. The overall design as well as both electron and photon beam properties are discussed.

  9. Application of FPGA technology for control of superconducting TESLA cavities in free electron laser

    NASA Astrophysics Data System (ADS)

    Pozniak, Krzysztof T.

    2006-10-01

    Contemporary fundamental research in physics, biology, chemistry, pharmacology, material technology and other uses frequently methods basing on collision of high energy particles or penetration of matter with ultra-short electromagnetic waves. Kinetic energy of involved particles, considerably greater than GeV, is generated in accelerators of unique construction. The paper presents a digest of working principles of accelerators. There are characterized research methods which use accelerators. A method to stabilize the accelerating EM field in superconducting (SC) resonant cavity was presented. An example was given of usage of TESLA cavities in linear accelerator propelling the FLASH free electron laser (FEL) in DESY, Hamburg. Electronic and photonic control system was debated. The system bases on advanced FPGA circuits and cooperating fast DSP microprocessor chips. Examples of practical solutions were described. Test results of the debated systems in the real-time conditions were given.

  10. D-zero rototrack: first stage of D-zero 2 Tesla solenoid field mapping device

    SciTech Connect

    Yamada, R.; Korienek, J.; Krider, J.; Lindenmeyer, C.; Miksa, D.; Miksa, R.

    1997-09-01

    A simple and portable field mapping device was developed at Fermilab and successfully used to test the D0 2 Tesla solenoid at Toshiba Works in Japan. A description of the mechanical structure, electric driving and control system, and software of the field mapping device is given. Four Hall probe elements of Group3 Digital Gaussmeters are mounted on the radial extension arm of a carriage, which is mounted on a central rotating beam. The system gives two dimensional motions (axial and rotational) to the Hall probes. To make the system compact and portable, we used a laptop computer with PCMCIA cards. For the control system we used commercially available software LabVIEW and Motion Toolbox, and for the data analysis we used Microsoft Excel.

  11. Optical Signatures from Magnetic 2-D Electron Gases in High Magnetic Fields to 60 Tesla

    SciTech Connect

    Crooker, S.A.; Kikkawa, J.M.; Awschalom, D.D.; Smorchikova, I.P.; Samarth, N.

    1998-11-08

    We present experiments in the 60 Tesla Long-Pulse magnet at the Los Alamos National High Magnetic Field Lab (NHMFL) focusing on the high-field, low temperature photoluminescence (PL) from modulation-doped ZnSe/Zn(Cd,Mn)Se single quantum wells. High-speed charge-coupled array detectors and the long (2 second) duration of the magnet pulse permit continuous acquisition of optical spectra throughout a single magnet shot. High-field PL studies of the magnetic 2D electron gases at temperatures down to 350mK reveal clear intensity oscillations corresponding to integer quantum Hall filling factors, from which we determine the density of the electron gas. At very high magnetic fields, steps in the PL energy are observed which correspond to the partial unlocking of antiferromagnetically bound pairs of Mn2+ spins.

  12. Mapping quantal touch using 7 Tesla functional magnetic resonance imaging and single-unit intraneural microstimulation.

    PubMed

    Sanchez Panchuelo, Rosa Maria; Ackerley, Rochelle; Glover, Paul M; Bowtell, Richard W; Wessberg, Johan; Francis, Susan T; McGlone, Francis

    2016-05-07

    Using ultra-high field 7 Tesla (7T) functional magnetic resonance imaging (fMRI), we map the cortical and perceptual responses elicited by intraneural microstimulation (INMS) of single mechanoreceptive afferent units in the median nerve, in humans. Activations are compared to those produced by applying vibrotactile stimulation to the unit's receptive field, and unit-type perceptual reports are analyzed. We show that INMS and vibrotactile stimulation engage overlapping areas within the topographically appropriate digit representation in the primary somatosensory cortex. Additional brain regions in bilateral secondary somatosensory cortex, premotor cortex, primary motor cortex, insula and posterior parietal cortex, as well as in contralateral prefrontal cortex are also shown to be activated in response to INMS. The combination of INMS and 7T fMRI opens up an unprecedented opportunity to bridge the gap between first-order mechanoreceptive afferent input codes and their spatial, dynamic and perceptual representations in human cortex.

  13. A test of a 2 Tesla superconducting transmission line magnet system

    SciTech Connect

    Piekarz, Henryk; Carcagno, Ruben; Claypool, Brad; Foster, George W.; Hays, Steven L.; Huang, Yuenian; Kashikhin, Vladimir; Malamud, Ernest; Mazur, Peter O.; Nehring, Roger; Oleck, Andrew; Rabehl, Roger; Schlabach, Phil; Sylvester, Cosmore; Velev, Gueorgui; Volk, James; Wake, Masayoshi; /KEK, Tsukuba

    2005-09-01

    Superconducting transmission line magnet test system for an injector accelerator of a staged VLHC proton-proton colliding beam accelerator has been built and operated at Fermilab. The 1.5 m long, twin-aperture, combined function dipole magnet of 2 Tesla field is excited by a single turn 100 kA transmission line superconductor. The 100 kA dc current is generated using dc-dc switching converters powered by a bulk 240 kW supply. A pair of horizontally placed conventional leads facilitates transfer of this current to the magnet transmission line superconductor operating at liquid helium temperature. Fabrication of magnet components and magnet assembly work are described. The magnet test system and its operation are presented, and the performance is summarized.

  14. Bunch Compressor Beamlines for the Tesla and S Band Linear Colliders

    SciTech Connect

    Emma, Paul J

    2003-06-20

    A detailed design for a single stage beam bunch length compressor for both the TESLA and the S-Band Linear Collider (SBLC) is presented. Compression is achieved by introducing an energy-position correlation along the bunch with an rf section at zero-crossing phase followed by a short bending section with energy dependent path length (momentum compaction). The motivation for a wiggler design is presented and many of the critical single bunch tolerances are evaluated. A solenoid based spin rotator is included in the design and transverse emittance tuning elements, diagnostics and tuning methods are described. Bunch length limitations due to second order momentum compaction and sinusoidal rf shape are discussed with options for compensation. Finally, the disadvantages of bunch compression using a 180{sup o} arc are discussed.

  15. 7 Tesla proton magnetic resonance spectroscopic imaging in adult X-linked adrenoleukodystrophy

    PubMed Central

    Ratai, Eva; Kok, Trina; Wiggins, Christopher; Wiggins, Graham; Grant, Ellen; Gagoski, Borjan; O'Neill, Gilmore; Adalsteinsson, Elfar; Eichler, Florian

    2010-01-01

    Background Adult patients with X-linked adrenoleukodystrophy (X-ALD) remain at risk for progressive neurological deterioration. Phenotypes vary in their pathology, ranging from axonal degeneration to inflammatory demyelination. The severity of symptoms is poorly explained by conventional imaging. Objective To test the hypothesis that neurochemistry in normal appearing brain differs among adult phenotypes of X-ALD, and that neurochemical changes correlate with the severity of symptoms. Patients and Methods Using a 7 Tesla scanner we performed structural and proton MRSI in 13 adult patients with X-ALD, including 4 patients with adult cerebral ALD (ACALD), 5 with adrenomyeloneuropathy (AMN) and 4 female heterozygotes. Studies were also performed in nine healthy controls. Results Among adult X-ALD phenotypes, MI/Cr was 46% higher and Cho/Cr 21% higher in normal appearing white matter of ACALD compared to AMN (p < 0.05). Both NAA/Cr and Glu/Cr ratios were lower in AMN patients (p = 0.028 and p = 0.036, respectively) than in controls. There were no significant differences between AMN and female heterozygotes. In cortex, ACALD patients had lower values of NAA/Cr compared to female heterozygotes and controls (p = 0.022). The global MI/Cr ratio demonstrated a significant association with the EDSS (Spearman ρ = 0.66, p = 0.039). Conclusion 7 Tesla proton MRSI reveals differences in the neurochemistry of ACALD but is unable to distinguish AMN from female heterozygotes. MI/Cr correlates with the severity of the symptoms and may be a meaningful biomarker in adult X-ALD. PMID:19001168

  16. A 10 Kelvin 3 Tesla Magnet for Space Flight ADR Systems

    NASA Technical Reports Server (NTRS)

    Tuttle, Jim; Shirron, Peter; Canavan, Edgar; DiPirro, Michael; Riall, Sara; Pourrahimi, Shahin

    2003-01-01

    Many future space flight missions are expected to use adiabatic demagnetization refrigerators (ADRs) to reach detector operating temperatures well below one Kelvin. The goal is to operate each ADR with a mechanical cooler as its heat sink, thus avoiding the use of liquid cryogens. Although mechanical coolers are being developed to operate at temperatures of 6 Kelvin and below, there is a large efficiency cost associated with operating them at the bottom of their temperature range. For the multi-stage ADR system being developed at Goddard Space Flight Center, the goal is to operate with a 10 Kelvin mechanical cooler heat sink. With currently available paramagnetic materials, the highest temperature ADR stage in such a system will require a magnetic field of approximately three Tesla. Thus the goal is to develop a small, lightweight three Tesla superconducting magnet for operation at 10 Kelvin. It is important that this magnet have a low current/field ratio. Because traditional NbTi magnets do not operate safely above about six Kelvin, a magnet with a higher Tc is required. The primary focus has been on Nb3Sn magnets. Since standard Nb3Sn wire must be coated with thick insulation, wound on a magnet mandrel and then reacted, standard Nb,Sn magnets are quite heavy and require high currents Superconducting Systems developed a Nb3Sn wire which can be drawn down to small diameter, reacted, coated with thin insulation and then wound on a small diameter coil form. By using this smaller wire and operating closer to the wire s critical current, it should be possible to reduce the mass and operating current of 10 Kelvin magnets. Using this "react-then-wind" technology, Superconducting Systems has produced prototype 10 Kelvin magnets. This paper describes the development and testing of these magnets and discusses the outlook for including 10 Kelvin magnets on space-flight missions.

  17. [Functional cerebral neuro-imaging at 1.5 Tesla. The results of visual, sensorimotor and auditory stimulations].

    PubMed

    Sabbah, P; Simond, G; Lèvrier, O; Murayama, N; Habib, M; Raybaud, C; Mazoyer, B; Briant, J F; Salamon, G

    1994-12-01

    Functional activation of the cerebral cortex can be observed with a standard 1.5 Tesla MRI magnet. We used a repeated FLASH 2D one-section sequence with a long echo (TE = 60 ms) and a small passing band. Modification of regional cerebral oxygenation due to neurone activation seems to be the main source of contrast. Sensorimotor stimulation was effected by an unusual mobilization of the fingers. Visual stimulation was performed by intermittent lightings at a frequency of 8 Hz. Auditory stimulation relied on listening to speech sounds. Signal increases were localized on the cerebral cortex with precise anatomico-functional correlation. Using a clinical 1.5 Tesla magnet requires an adequate treatment of data. Thus, stimulated cerebral activity can be portrayed by MRI therapy opening a new way for anatomico-functional cerebral studies.

  18. Construction and component testing of TAMU3, a 14 Tesla stress-managed Nb3Sn model dipole

    NASA Astrophysics Data System (ADS)

    Holik, Eddie Frank, III; Benson, Chris; Blackburn, Raymond; Diaczenko, Nick; Elliott, Timothy; Jaisle, Andrew; McInturff, A.; McIntyre, P.; Sattarov, Akhdiyor

    2012-06-01

    We report the construction and testing of components of TAMU3, a 14 Tesla Nb3Sn block-coil dipole. A primary goal in developing this model dipole is to test a method of stress management in which Lorentz stress is intercepted within the coil assembly and bypassed so that it cannot accumulate to a level that would cause strain degradation in the superconducting windings. Details of the fabrication, tooling, and results of construction and magnet component testing will be presented.

  19. Modules for 6.0 Tesla, vertically separated, clustered or distributed lattices

    SciTech Connect

    Peggs, S.

    1985-10-01

    A total of four lattices have been designed for distributed and (3,3) clustered versions of the SSC, and are available in the SSC database, SSCDB. These lattices are constructed of the same four basic modules, which with only minor tuning can be re-organised to form many conceivable realistic geometries. One module is trivial, consisting of regular cells in a long main arc. The description of the other three modules is the central theme of this report. Potential improvements in both the modules and their implementation are also mentioned. The lattices, with the generic name VSDlbnn.DAT, are in MAD/standard input format in the [SSCDB.LATTICES] directory of the database. Lower case letters in the generic name represent variable characters, where {open_quotes}b{close_quotes} is either C or D, according to whether the lattice is (3,3) Clustered or Distributed, and where {open_quotes}nn{close_quotes} is 01 or 10, according to whether the collision beta is {beta}{sup *} = 1.0 or 10.0 metres, in luminosity or injection lattices. The general title {open_quotes}VS{close_quotes} stands for the Vertical Separation of the two beam lines, with a (total) separation in the main arcs of 0.70 metres, while the notation {open_quotes}Dl{close_quotes} reflects the regular cell dipoles of 6.0 Tesla ({open_quotes}D{close_quotes}), with a phase advance per cell of 60 degrees ({open_quotes}1{close_quotes}). The half cell length is 100 metres. It would be useful for lattice designers and users in the SSC design community to agree on some such lattice naming convention, even if the agreement is merely informal. Two criticisms of the above convention are first, that since the magnet selection for the SSC has fixed the dipole field to be close to 6.4 Tesla, the {open_quotes}D{close_quotes} definition of dipole strength is redundant, and second, that collision betas of less than 1.0 metre can not be handled unless three digits, {open_quotes}nnn{close_quotes}, are included.

  20. MOPA FEL Scheme as a Source of Primary Photons for Gamma-Gamma Collider at TESLA and SBLC

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    1997-05-01

    The project of a Linear Collider (TESLA and SBLC options) is developed by the international TESLA collaboration. This project includes the second interaction region for γ γ and γe collisions as an additional option. High energy gamma-quanta are produced in the process of Compton backscattering of the laser photons on the electrons of the main linear accelerator. In the present study of the Linear Collider Project it has been accepted to use Master Oscillator -- Power Amplifier (MOPA) free electron laser (FEL) scheme as a laser system. In this scheme the optical pulse from Nd glass laser (λ = 1 μm, 1 MW peak power) is amplified by FEL amplifier up to the power of about 500 GW. These parameters of the laser system allows one to obtain 70 % conversion efficiency of the electrons into high energy gamma-quanta. The driving beam for the FEL amplifier is produced by the linear rf accelerator identical to the main accelerator, but with lower accelerating gradient due to higher beam load. Such a choice fits well to both TESLA and SBLC options. It is important that the requirements to the parameters of the FEL driving electron beam are rather moderate and can be provided by injector consisting of gridded thermoionic gun and subharmonic buncher.

  1. Mapping quantal touch using 7 Tesla functional magnetic resonance imaging and single-unit intraneural microstimulation

    PubMed Central

    Sanchez Panchuelo, Rosa Maria; Ackerley, Rochelle; Glover, Paul M; Bowtell, Richard W; Wessberg, Johan

    2016-01-01

    Using ultra-high field 7 Tesla (7T) functional magnetic resonance imaging (fMRI), we map the cortical and perceptual responses elicited by intraneural microstimulation (INMS) of single mechanoreceptive afferent units in the median nerve, in humans. Activations are compared to those produced by applying vibrotactile stimulation to the unit’s receptive field, and unit-type perceptual reports are analyzed. We show that INMS and vibrotactile stimulation engage overlapping areas within the topographically appropriate digit representation in the primary somatosensory cortex. Additional brain regions in bilateral secondary somatosensory cortex, premotor cortex, primary motor cortex, insula and posterior parietal cortex, as well as in contralateral prefrontal cortex are also shown to be activated in response to INMS. The combination of INMS and 7T fMRI opens up an unprecedented opportunity to bridge the gap between first-order mechanoreceptive afferent input codes and their spatial, dynamic and perceptual representations in human cortex. DOI: http://dx.doi.org/10.7554/eLife.12812.001 PMID:27154626

  2. MEG evaluation of pico-Tesla external TMS on multiple sclerosis patients.

    PubMed

    Anninos, P; Adamopoulos, A; Kotini, A; Tsagas, N

    2016-07-01

    Magnetoencephalographic (MEG) recordings of 10 multiple sclerosis (MS) patients (2 men, 8 women, mean 41.3±9.5 years, mean disease duration 12.7±7.2 years) were obtained using a whole-head 122 - channel MEG system in a magnetically shielded room of low magnetic noise. Our experimental design was double-blind in order to look for possible effect of external pico - Tesla Transcranial Magnetic Stimulation (pT-TMS). The external pT-TMS was applied on the MS patients with proper field characteristics (magnetic field amplitude: 1-7.5pT, frequency: the alpha-rhythm of the patient 8-13Hz) which were obtained prior to the application of pT-TMS. Each MS patient had two separate recording sessions consisting of 3 runs in between where were given real or sham pT-TMS. It was then tried to predict the real and sham stimulation sessions based on the changes in the mean peak frequency difference (MPFD) observed in the brain of the patients in the 2-7Hz frequency band. After unblinding it was found a significant effect of an increase of frequencies in the range of 2-7Hz across the subjects followed by an improvement and normalization of the MEG. PMID:27456873

  3. The Safety of MR Conditional Cochlear Implant at 1.5 Tesla Magnetic Resonance Imaging System.

    PubMed

    Takahashi, Daisuke; Ogura, Akio; Hayashi, Norio; Seino, Shinya; Kawai, Ryosuke; Matsuda, Tsuyoshi; Doi, Tsukasa; Tsuchihashi, Toshio

    2016-08-01

    In magnetic resonance imaging (MRI) examination of the patients with the cochlear implant, only limited data have a mention for safety information in the instruction manual supplied by the manufacturers. Therefore, imaging operators require more detailed safety information for implant device. We conducted detailed examination about displacement force, torque, and demagnetizing of the cochlear implant magnet based on American Society for Testing and Materials (ASTM) standard using the PULSAR and CONCERTO (MED-EL) with 1.5 tesla MRI system. As a result, the displacement force and the torque of the implant magnet were less than the numerical values descried in the manual. Therefore, these have almost no effect on the body under the condition described in a manual. In addition, the demagnetizing factor of the cochlear implant magnet occurred by a change magnetic field. The demagnetization depended on the direction of a line of magnetic force of the static magnetic field and the implant magnet. In conclusion, the operator must warn the position of the patients on inducing in the magnet room. PMID:27546081

  4. Studies on a VUV free electron laser at the TESLA Test Facility at DESY

    SciTech Connect

    Rossbach, J.

    1995-12-31

    The TESLA Test Facility (TTF) currently under construction at DESY is a test-bed for acceleration sections of a high-gradient, high efficiency superconducting linear collider. Due to ist unrivaled ability to sustain high beam quality during acceleration, a superconducting rf linac is considered the optimum choice to drive a Free Electron Laser (FEL). We aim at a photon wavelength of {lambda} = 6 manometer utilizing the TTF after is has been extended to 1 GeV beam energy. Due to lack of mirrors and seed-lasers in this wavelength regime, a single pass FEL and Self-Amplified-Spontaneous-Emission (SASE) is considered. A first test is foreseen at a larger photon wavelength. The overall design as well as both electron and photon beam properties will be discussed. To reach the desired photon wavelength, the main components that have to be added to the TTF are: (a) a low emittance rf gun including space charge compensation (b) a two stage bunch compressor increasing the peak bunch current from 100 A up to 2500 A (c) four more accelerating modules to achieve 1 GeV beam energy (d) a 25 m long undulator (period length 27 mm, peak field 0.5 T) The average brillance will be larger than 1-10{sup 22}photons/s/mm{sup 2}/mrad{sup 2}/0.1%. Each 800 {mu}s long pulse will contain up to 7200 equidistant bunches. The repetition frequency of the linac is 10 Hz.

  5. A Tesla-pulse forming line-plasma opening switch pulsed power generator.

    PubMed

    Novac, B M; Kumar, R; Smith, I R

    2010-10-01

    A pulsed power generator based on a high-voltage Tesla transformer which charges a 3.85 Ω/55 ns water-filled pulse forming line to 300 kV has been developed at Loughborough University as a training tool for pulsed power students. The generator uses all forms of insulation specific to pulsed power technology, liquid (oil and water), gas (SF(6)), and magnetic insulation in vacuum, and a number of fast voltage and current sensors are implemented for diagnostic purposes. A miniature (centimeter-size) plasma opening switch has recently been coupled to the output of the pulse forming line, with the overall system comprising the first phase of a program aimed at the development of a novel repetitive, table-top generator capable of producing 15 GW pulses for high power microwave loads. Technical details of all the generator components and the main experimental results obtained during the program and demonstrations of their performance are presented in the paper, together with a description of the various diagnostic tools involved. In particular, it is shown that the miniature plasma opening switch is capable of reducing the rise time of the input current while significantly increasing the load power. Future plans are outlined in the conclusions.

  6. Feasibility of MHD submarine propulsion. Phase II, MHD propulsion: Testing in a two Tesla test facility

    SciTech Connect

    Doss, E.D.; Sikes, W.C.

    1992-09-01

    This report describes the work performed during Phase 1 and Phase 2 of the collaborative research program established between Argonne National Laboratory (ANL) and Newport News Shipbuilding and Dry Dock Company (NNS). Phase I of the program focused on the development of computer models for Magnetohydrodynamic (MHD) propulsion. Phase 2 focused on the experimental validation of the thruster performance models and the identification, through testing, of any phenomena which may impact the attractiveness of this propulsion system for shipboard applications. The report discusses in detail the work performed in Phase 2 of the program. In Phase 2, a two Tesla test facility was designed, built, and operated. The facility test loop, its components, and their design are presented. The test matrix and its rationale are discussed. Representative experimental results of the test program are presented, and are compared to computer model predictions. In general, the results of the tests and their comparison with the predictions indicate that thephenomena affecting the performance of MHD seawater thrusters are well understood and can be accurately predicted with the developed thruster computer models.

  7. MEG evaluation of pico-Tesla external TMS on multiple sclerosis patients.

    PubMed

    Anninos, P; Adamopoulos, A; Kotini, A; Tsagas, N

    2016-07-01

    Magnetoencephalographic (MEG) recordings of 10 multiple sclerosis (MS) patients (2 men, 8 women, mean 41.3±9.5 years, mean disease duration 12.7±7.2 years) were obtained using a whole-head 122 - channel MEG system in a magnetically shielded room of low magnetic noise. Our experimental design was double-blind in order to look for possible effect of external pico - Tesla Transcranial Magnetic Stimulation (pT-TMS). The external pT-TMS was applied on the MS patients with proper field characteristics (magnetic field amplitude: 1-7.5pT, frequency: the alpha-rhythm of the patient 8-13Hz) which were obtained prior to the application of pT-TMS. Each MS patient had two separate recording sessions consisting of 3 runs in between where were given real or sham pT-TMS. It was then tried to predict the real and sham stimulation sessions based on the changes in the mean peak frequency difference (MPFD) observed in the brain of the patients in the 2-7Hz frequency band. After unblinding it was found a significant effect of an increase of frequencies in the range of 2-7Hz across the subjects followed by an improvement and normalization of the MEG.

  8. Multi-contrast submillimetric 3 Tesla hippocampal subfield segmentation protocol and dataset.

    PubMed

    Kulaga-Yoskovitz, Jessie; Bernhardt, Boris C; Hong, Seok-Jun; Mansi, Tommaso; Liang, Kevin E; van der Kouwe, Andre J W; Smallwood, Jonathan; Bernasconi, Andrea; Bernasconi, Neda

    2015-01-01

    The hippocampus is composed of distinct anatomical subregions that participate in multiple cognitive processes and are differentially affected in prevalent neurological and psychiatric conditions. Advances in high-field MRI allow for the non-invasive identification of hippocampal substructure. These approaches, however, demand time-consuming manual segmentation that relies heavily on anatomical expertise. Here, we share manual labels and associated high-resolution MRI data (MNI-HISUB25; submillimetric T1- and T2-weighted images, detailed sequence information, and stereotaxic probabilistic anatomical maps) based on 25 healthy subjects. Data were acquired on a widely available 3 Tesla MRI system using a 32 phased-array head coil. The protocol divided the hippocampal formation into three subregions: subicular complex, merged Cornu Ammonis 1, 2 and 3 (CA1-3) subfields, and CA4-dentate gyrus (CA4-DG). Segmentation was guided by consistent intensity and morphology characteristics of the densely myelinated molecular layer together with few geometry-based boundaries flexible to overall mesiotemporal anatomy, and achieved excellent intra-/inter-rater reliability (Dice index ≥90/87%). The dataset can inform neuroimaging assessments of the mesiotemporal lobe and help to develop segmentation algorithms relevant for basic and clinical neurosciences. PMID:26594378

  9. Measurement and evaluation of the acoustic noise of a 3 Tesla MR scanner.

    PubMed

    Hattori, Yoko; Fukatsu, Hiroshi; Ishigaki, Takeo

    2007-01-01

    We measured the sound level and frequencies of the acoustic noise generated by a 3 Tesla (T) MR scanner, and investigated the subjective sound level for 30 healthy volunteers with either earplugs, headphones or both. The sound level of 3T was found to be higher than that of 1.5T in all sequences. The peak sound pressure level of 3T ranged from 125.7 dB for MR angiography to 130.7 dB for single shot EPI on the linear scale. The equivalent noise level was from 110.0 dB for FLAIR to 115.8 dB for T1-IR on the A-weighted scale, which exceeded 99 dB, the level regulated by the International Electrotechnical Commission (IEC). The study of the subjective sound level showed that the effect of noise reduction was not significantly different between earplugs and headphones. However, the use of both devices could reduce the subjective sound level significantly better than either one alone (P < 0.01). Thus we propose wearing both devices for ear-protection during 3T examinations.

  10. Customization of normal data base specific for 3-tesla MRI is mandatory in VSRAD analysis.

    PubMed

    Goto, Masami; Suzuki, Yuuichi; Abe, Osamu; Hayashi, Naoto; Aoki, Shigeki; Mori, Harushi; Masumoto, Tomohiko; Watanabe, Yasushi; Satake, Yoshirou; Ino, Kenji; Yano, Keiichi; Iida, Kyouhito; Mima, Kazuo; Ohtomo, Kuni

    2008-07-01

    A voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) was used for quantitative analysis of parahippocampal atropy with 1.5-tesla (T) MRI in a voxel-wise manner. The analysis of images acquired under a different imaging condition provides an error factor that has a calculated value. Clinical application of 3T-MRI is necessary for establishing a normal data base (N-DB) specific for 3T-MRI data, which permits appropriate application of VSRAD. We established an N-DB specific for 3T-MRI for use in VSRAD. The "Z-score of the parahippocampal gyrus" was 0.79 +/- 0.32, and the N-DB of each age group did not have a big deflection when we analyzed a group of physically unimpaired persons in an N-DB specific for 3T-MRI. Therefore, we were able to confirm the validity of the customized N-DB. The "Z-score of the parahippocampal gyrus" was 1.62 +/- 0.47 for the N-DB of VSRAD. The numerical value was high for the group of physically unimpaired persons.

  11. Effect of 1. 5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers

    SciTech Connect

    Hayes, D.L.; Holmes, D.R. Jr.; Gray, J.E.

    1987-10-01

    Patients with a permanent pacemaker are currently restricted from diagnostic nuclear magnetic resonance (NMR) imaging because of potential adverse effects on the pacemaker by the magnet. Previous work has shown that NMR imaging will result in asynchronous pacing of the pulse generator within a given distance of the magnet. The radiofrequency signal generated by the system may also result in rapid cardiac pacing, which may have deleterious effects. This study utilized a 1.5 tesla unit in an in vivo laboratory animal to evaluate the unit's effects on eight different pulse generators from two manufacturers. All pacemakers functioned in an asynchronous mode when placed within a certain distance of the magnet. In addition, transient reed switch inhibition was observed. Seven of the eight pulse generators paced rapidly when exposed to the radiofrequency signal and there was a dramatic decrease in arterial blood pressure. Whether effective rapid cardiac pacing would occur could not be predicted before exposure to the magnetic resonance unit. Nuclear magnetic resonance imaging with high magnetic fields in patients with a pacemaker should continue to be avoided until the mechanism of the rapid cardiac pacing can be further delineated and either predicted or prevented.

  12. An efficient tensor transpose algorithm for multicore CPU, Intel Xeon Phi, and NVidia Tesla GPU

    DOE PAGES

    Lyakh, Dmitry I.

    2015-01-05

    An efficient parallel tensor transpose algorithm is suggested for shared-memory computing units, namely, multicore CPU, Intel Xeon Phi, and NVidia GPU. The algorithm operates on dense tensors (multidimensional arrays) and is based on the optimization of cache utilization on x86 CPU and the use of shared memory on NVidia GPU. From the applied side, the ultimate goal is to minimize the overhead encountered in the transformation of tensor contractions into matrix multiplications in computer implementations of advanced methods of quantum many-body theory (e.g., in electronic structure theory and nuclear physics). A particular accent is made on higher-dimensional tensors that typicallymore » appear in the so-called multireference correlated methods of electronic structure theory. Depending on tensor dimensionality, the presented optimized algorithms can achieve an order of magnitude speedup on x86 CPUs and 2-3 times speedup on NVidia Tesla K20X GPU with respect to the na ve scattering algorithm (no memory access optimization). Furthermore, the tensor transpose routines developed in this work have been incorporated into a general-purpose tensor algebra library (TAL-SH).« less

  13. An efficient tensor transpose algorithm for multicore CPU, Intel Xeon Phi, and NVidia Tesla GPU

    SciTech Connect

    Lyakh, Dmitry I.

    2015-01-05

    An efficient parallel tensor transpose algorithm is suggested for shared-memory computing units, namely, multicore CPU, Intel Xeon Phi, and NVidia GPU. The algorithm operates on dense tensors (multidimensional arrays) and is based on the optimization of cache utilization on x86 CPU and the use of shared memory on NVidia GPU. From the applied side, the ultimate goal is to minimize the overhead encountered in the transformation of tensor contractions into matrix multiplications in computer implementations of advanced methods of quantum many-body theory (e.g., in electronic structure theory and nuclear physics). A particular accent is made on higher-dimensional tensors that typically appear in the so-called multireference correlated methods of electronic structure theory. Depending on tensor dimensionality, the presented optimized algorithms can achieve an order of magnitude speedup on x86 CPUs and 2-3 times speedup on NVidia Tesla K20X GPU with respect to the na ve scattering algorithm (no memory access optimization). Furthermore, the tensor transpose routines developed in this work have been incorporated into a general-purpose tensor algebra library (TAL-SH).

  14. Test Results for HD1, a 16 Tesla Nb3Sn Dipole Magnet

    SciTech Connect

    Lietzke, A.F.; Bartlett, S.; Bish, P.; Caspi, S.; Chiesa, L.; Dietderich, D.; Ferracin, P.; Gourlay, S.A.; Goli, M.; Hafalia, R.R.; Higley, H.; Hannaford, R.; Lau, W.; Liggens, N.; Mattafirri, S.; McInturff, A.; Nyman, M.; Sabbi, G.; Scanlan, R.; Swanson, J.

    2003-10-01

    The Superconducting Magnet Group at Lawrence Berkeley National Laboratory has been developing the technology for using brittle superconductor in high-field accelerator magnets. HD1, the latest in a series of magnets, contains two, double-layer Nb{sub 3}Sn flat racetrack coils. This single-bore dipole configuration, using the highest performance conductor available, was designed and assembled for a 16 tesla conductor/structure/pre-stress proof-of-principle. With the combination of brittle conductor and high Lorentz stress, considerable care was taken to predict the magnet's mechanical responses to pre-stress, cool-down, and excitation. Subsequent cold testing satisfied expectations: Training started at 13.6 T, 83% of 'short-sample', achieved 90% in 10 quenches, and reached its peak bore field (16 T) after 19 quenches. The average plateau, {approx}92% of 'short-sample', appeared to be limited by 'stick-slip' conductor motions, consistent with the 16.2 T conductor 'lift-off' pre-stress that was chosen for this first test. Some lessons learned and some implications for future conductor and magnet technology development are presented and discussed.

  15. Performance Analysis of Memory Transfers and GEMM Subroutines on NVIDIA Tesla GPU Cluster

    SciTech Connect

    Allada, Veerendra, Benjegerdes, Troy; Bode, Brett

    2009-08-31

    Commodity clusters augmented with application accelerators are evolving as competitive high performance computing systems. The Graphical Processing Unit (GPU) with a very high arithmetic density and performance per price ratio is a good platform for the scientific application acceleration. In addition to the interconnect bottlenecks among the cluster compute nodes, the cost of memory copies between the host and the GPU device have to be carefully amortized to improve the overall efficiency of the application. Scientific applications also rely on efficient implementation of the BAsic Linear Algebra Subroutines (BLAS), among which the General Matrix Multiply (GEMM) is considered as the workhorse subroutine. In this paper, they study the performance of the memory copies and GEMM subroutines that are critical to port the computational chemistry algorithms to the GPU clusters. To that end, a benchmark based on the NetPIPE framework is developed to evaluate the latency and bandwidth of the memory copies between the host and the GPU device. The performance of the single and double precision GEMM subroutines from the NVIDIA CUBLAS 2.0 library are studied. The results have been compared with that of the BLAS routines from the Intel Math Kernel Library (MKL) to understand the computational trade-offs. The test bed is a Intel Xeon cluster equipped with NVIDIA Tesla GPUs.

  16. Human brain diffusion tensor imaging at submillimeter isotropic resolution on a 3Tesla clinical MRI scanner.

    PubMed

    Chang, Hing-Chiu; Sundman, Mark; Petit, Laurent; Guhaniyogi, Shayan; Chu, Mei-Lan; Petty, Christopher; Song, Allen W; Chen, Nan-kuei

    2015-09-01

    The advantages of high-resolution diffusion tensor imaging (DTI) have been demonstrated in a recent post-mortem human brain study (Miller et al., NeuroImage 2011;57(1):167-181), showing that white matter fiber tracts can be much more accurately detected in data at a submillimeter isotropic resolution. To our knowledge, in vivo human brain DTI at a submillimeter isotropic resolution has not been routinely achieved yet because of the difficulty in simultaneously achieving high resolution and high signal-to-noise ratio (SNR) in DTI scans. Here we report a 3D multi-slab interleaved EPI acquisition integrated with multiplexed sensitivity encoded (MUSE) reconstruction, to achieve high-quality, high-SNR and submillimeter isotropic resolution (0.85×0.85×0.85mm(3)) in vivo human brain DTI on a 3Tesla clinical MRI scanner. In agreement with the previously reported post-mortem human brain DTI study, our in vivo data show that the structural connectivity networks of human brains can be mapped more accurately and completely with high-resolution DTI as compared with conventional DTI (e.g., 2×2×2mm(3)).

  17. Effect of Plasma Modulation on the Corona of a Tesla Coil

    NASA Astrophysics Data System (ADS)

    Clayton, Robert; Schneider, Hans; Zwicker, Andrew

    2011-10-01

    Modulating an audio signal into a Tesla coil, one can create a plasma speaker. Documented use of plasma speakers dates back to 1900 with William Duddell's singing arc. In order to understand the mechanisms present in plasma speaker, and further the research that has been done by Nicholas Braithwaite, et al. in observing audio modulation in plasma (Visualizing Gas Heating from an RF Plasma Loudspeaker; 2008); a plasma speaker was constructed with a 4 MHz plasma frequency providing ~10,000 volts in the secondary coil, which generates a 1-inch corona emitted from the electrode. The 4 MHz signal is outside of the audio range, therefore any audio signal can be modulated on top of the plasma without approaching the frequency of the plasma. A high speed video camera is used to look at plasma dynamics as a function of electrode shape and input power. Providing pure tones to modulate the speaker, the emitted corona will be analyzed at a frame rate at or above the frequency of the test signal to determine the effects of the modulation on the plasma. Audio quality will be studied with a frequency analyzer and correlated to plasma parameters.

  18. A unique 30 Tesla single-solenoid pulsed magnet instrument for x-ray studies

    NASA Astrophysics Data System (ADS)

    Islam, Zahirul; Capatina, Dana; Ruff, Jacob; Das, Ritesh; Nojiri, Hiroyuki; Narumi, Yasuo

    2011-03-01

    We present a dual-cryostat pulsed-magnet instrument at the Advanced Photon Source (APS) with unique capabilities. The dual-cryostat independently cools the solenoid (Tohoku design) using liquid nitrogen and the sample using a closed-cycle refrigerator, respectively. Liquid nitrogen (LN) cooling allows a repetition rate of seven minutes for peak fields of 30 Tesla. The system is unique in that the LN cryostat incorporates a double-funnel vacuum tube passing through the solenoid's bore preserving the entire angular range allowed by the magnet. This scheme is advantageous in that it allows the applied magnetic field to be parallel to the scattering plane complementing typical split-pair magnets with fields normal to the scattering plane. Performance of the coils along with preliminary x-ray diffraction and spectroscopic studies will be presented. Use of the APS is supported by the U. S. DOE, Office of Science, under Contract No. DE-AC02-06CH11357. The work was supported in part by ICC-IMR, Tohoku University.

  19. Practical Methods for Improving B1+ Homogeneity in 3 Tesla Breast Imaging

    PubMed Central

    Winkler, Simone A.; Rutt, Brian K.

    2016-01-01

    Purpose To improve image contrast and B1+ field homogeneity in 3 Tesla (T) breast MR. Materials and Methods Two practical B1+ shimming methods for 3T breast MR are presented; low-cost passive shimming using local pads of high dielectric permittivity (εr from 0 to 100), and two-channel radiofrequency (RF) shimming (adjusting Q-I amplitude ratios and phase differences of 0 to −4 dB and 90 to 45 degrees), as well as a combination of both methods. The technique has been studied both in simulation using a numerical body model with added mammary tissue and in vivo in six subjects. Results Large improvements are observed with both methods, leading to a decrease in left–right B1+ asymmetry ratio of 1.24 to 1.00 (simulation) and from 1.26 to 1.01 (in vivo). RF safety was not adversely affected. Conclusion Both RF shimming and dielectric shimming were shown to improve inhomogeneity in the B1+ field in 3T breast MR. PMID:24723508

  20. Dynamic Multi-Coil Shimming of the Human Brain at 7 Tesla

    PubMed Central

    Juchem, Christoph; Nixon, Terence W.; McIntyre, Scott; Boer, Vincent O.; Rothman, Douglas L.; de Graaf, Robin A.

    2011-01-01

    High quality magnetic field homogenization of the human brain (i.e. shimming) for MR imaging and spectroscopy is a demanding task. The susceptibility differences between air and tissue are a longstanding problem as they induce complex field distortions in the prefrontal cortex and the temporal lobes. To date, the theoretical gains of high field MR have only been realized partially in the human brain due to limited magnetic field homogeneity. A novel shimming technique for the human brain is presented that is based on the combination of non-orthogonal basis fields from 48 individual, circular coils. Custom-built amplifier electronics enabled the dynamic application of the multi-coil shim fields in a slice-specific fashion. Dynamic multi-coil (DMC) shimming is shown to eliminate most of the magnetic field inhomogeneity apparent in the human brain at 7 Tesla and provided improved performance compared to state-of-the-art dynamic shim updating with zero through third order spherical harmonic functions. The novel technique paves the way for high field MR applications of the human brain for which excellent magnetic field homogeneity is a prerequisite. PMID:21824794

  1. Performance of external and internal coil configurations for prostate investigations at 7 Tesla

    PubMed Central

    Metzger, Gregory J.; van de Moortele, Pierre-Francois; Akgun, Can; Snyder, Carl J.; Moeller, Steen; Strupp, John; Andersen, Peter; Shrivastava, Devashish; Vaughan, Tommy; Ugurbil, Kamil; Adriany, Gregor

    2010-01-01

    Three different coil configurations were evaluated through simulation and experimentally to determine safe operating limits and evaluate subject size dependent performance for prostate imaging at 7 Tesla. The coils included a transceiver endorectal coil (trERC), a 16 channel transceiver external surface array (trESA) and a trESA combined with a receive-only ERC (trESA+roERC). While the transmit B1 (B1+) homogeneity was far superior for the trESA, the maximum achievable B1+ is subject size dependent and limited by transmit chain losses and amplifier performance. For the trERC, limitations in transmit homogeneity greatly compromised image quality and limited coverage of the prostate. Despite these challenges, the high peak B1+ close to the trERC and subject size independent performance provides potential advantages especially for spectroscopic localization where high bandwidth RF pulses are required. On the receive side, the combined trESA+roERC provided the highest SNR and improved homogeneity over the trERC resulting in better visualization of the prostate and surrounding anatomy. In addition, the parallel imaging performance of the trESA+roERC holds strong promise for diffusion weighted imaging and dynamic contrast enhanced MRI. PMID:20740657

  2. The Safety of MR Conditional Cochlear Implant at 1.5 Tesla Magnetic Resonance Imaging System.

    PubMed

    Takahashi, Daisuke; Ogura, Akio; Hayashi, Norio; Seino, Shinya; Kawai, Ryosuke; Matsuda, Tsuyoshi; Doi, Tsukasa; Tsuchihashi, Toshio

    2016-08-01

    In magnetic resonance imaging (MRI) examination of the patients with the cochlear implant, only limited data have a mention for safety information in the instruction manual supplied by the manufacturers. Therefore, imaging operators require more detailed safety information for implant device. We conducted detailed examination about displacement force, torque, and demagnetizing of the cochlear implant magnet based on American Society for Testing and Materials (ASTM) standard using the PULSAR and CONCERTO (MED-EL) with 1.5 tesla MRI system. As a result, the displacement force and the torque of the implant magnet were less than the numerical values descried in the manual. Therefore, these have almost no effect on the body under the condition described in a manual. In addition, the demagnetizing factor of the cochlear implant magnet occurred by a change magnetic field. The demagnetization depended on the direction of a line of magnetic force of the static magnetic field and the implant magnet. In conclusion, the operator must warn the position of the patients on inducing in the magnet room.

  3. Human brain diffusion tensor imaging at submillimeter isotropic resolution on a 3 Tesla clinical MRI scanner

    PubMed Central

    Chang, Hing-Chiu; Sundman, Mark; Petit, Laurent; Guhaniyogi, Shayan; Chu, Mei-Lan; Petty, Christopher; Song, Allen W.; Chen, Nan-kuei

    2015-01-01

    The advantages of high-resolution diffusion tensor imaging (DTI) have been demonstrated in a recent post-mortem human brain study (Miller et al., NeuroImage 2011;57(1):167–181), showing that white matter fiber tracts can be much more accurately detected in data at submillimeter isotropic resolution. To our knowledge, in vivo human brain DTI at submillimeter isotropic resolution has not been routinely achieved yet because of the difficulty in simultaneously achieving high resolution and high signal-to-noise ratio (SNR) in DTI scans. Here we report a 3D multi-slab interleaved EPI acquisition integrated with multiplexed sensitivity encoded (MUSE) reconstruction, to achieve high-quality, high-SNR and submillimeter isotropic resolution (0.85 × 0.85 × 0.85 mm3) in vivo human brain DTI on a 3 Tesla clinical MRI scanner. In agreement with the previously reported post-mortem human brain DTI study, our in vivo data show that the structural connectivity networks of human brains can be mapped more accurately and completely with high-resolution DTI as compared with conventional DTI (e.g., 2 × 2 × 2 mm3). PMID:26072250

  4. Prototype of 10 Tesla Water Cooled Bitter-type Magnet System

    NASA Astrophysics Data System (ADS)

    Bates, E. M.; Birmingham, W. J.; Riverva, W. F.; Romero-Talamas, C. A.

    2015-11-01

    A 1 Tesla water cooled Bitter-type magnetic system has been designed and is under construction at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County (UMBC). It is a scaled version of a 10 T Bitter-type magnet that will be used in dusty plasma experiments where dust larger than 500 nm diameter will be strongly magnetized. We present here the design methods used for both magnets, and discuss the design parameters that drive the magnet cooling and power storage bank subsystems. The pressure vessel and plasma vacuum chamber subsystems are then built with the aforementioned subsystems as constraints. To validate our design, magnetic field and temperature measurements within the prototype magnet are compared to finite element analysis (FEA) and analytical methods used for preliminary designing. This knowledge will be used to finalize the 10 T magnet design. Once operational, the 10 T magnet will be programmable to be on for at least ten seconds to several minutes, with up to 20 plasma events planned per day.

  5. Efficient frequency doubler for the soft X-ray SASE FEL at the TESLA Test Facility

    NASA Astrophysics Data System (ADS)

    Feldhaus, J.; Körfer, M.; Möller, T.; Pflüger, J.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    2004-08-01

    This paper describes an effective frequency doubler scheme for SASE free electron lasers (FEL). It consists of an undulator tuned to the first harmonic, a dispersion section, and a tapered undulator tuned to the second harmonic. The first stage is a conventional soft X-ray SASE FEL. Its gain is controlled in such a way that the maximum energy modulation of the electron beam at the exit is about equal to the local energy spread, but still far away from saturation. When the electron bunch passes through the dispersion section this energy modulation leads to effective compression of the particles. Then the bunched electron beam enters the tapered undulator and produces strong radiation in the process of coherent deceleration. We demonstrate a frequency doubler scheme that can be integrated into the SASE FEL at the TESLA Test Facility at DESY, and will allow to reach 3 nm wavelength with GW-level of output peak power. This would extend the operating range of the FEL into the so-called water window and significantly expand the capabilities of the TTF FEL user facility.

  6. Constructing a 4-TESLA Large Thin Solenoid at the Limit of what can BE Safely Operated

    NASA Astrophysics Data System (ADS)

    Hervé, A.

    The 4-tesla, 6 m free bore CMS solenoid has been successfully tested, operated and mapped at CERN during the autumn of 2006 in a surface hall and fully recommissioned in the underground experimental area in the autumn of 2008. The conceptual design started in 1990, the R&D studies in 1993, and the construction was approved in 1997. At the time the main parameters of this project were considered beyond what was thought possible as, in particular, the total stored magnetic energy reaches 2.6 GJ for a specific magnetic energy density exceeding 11 kJ/kg of cold mass. During this period, the international design and construction team had to make several important technical choices, particularly mechanical ones, to maximize the chances of reaching the nominal induction of 4 T. These design choices are explained and critically reviewed in the light of what is presently known to determine if better solutions would be possible today for constructing a new large high-field thin solenoid for a future detector magnet.

  7. Start-to-end simulations of SASE FEL at the TESLA Test Facility, phase 1

    NASA Astrophysics Data System (ADS)

    Dohlus, M.; Flöttmann, K.; Kozlov, O. S.; Limberg, T.; Piot, Ph.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    2004-09-01

    Phase 1 of the vacuum ultra-violet free-electron laser (FEL) at the TESLA Test Facility recently concluded operation. It successfully demonstrated the saturation of a SASE FEL in the wavelength range of 80-120 nm. We present a posteriori start-to-end numerical simulations of this FEL. These simulations are based on the programs Astra and elegant for the generation and transport of the electron distribution. An independent simulation of the intricate beam dynamics in the magnetic bunch compressor is performed with the program CSRtrack. The SASE FEL process is simulated with the code FAST. From our detailed simulations and the resulting phase space distribution at the undulator entrance, we found that the FEL was driven only by a small fraction (slice) of the electron bunch. This "lasing slice" is located in the head of the bunch, and has a peak current of approximately 3 kA. A strong energy chirp (due to the space charge field after compression) within this slice had a significant influence on the FEL operation. Our study shows that the radiation pulse duration is about 40 fs (FWHM) with a corresponding peak power of 1.5 GW. The simulated FEL properties are compared with various experimental data and found to be in excellent agreement.

  8. Two-Slotted Surface Coil Array for Magnetic Resonance Imaging at 4 Tesla

    SciTech Connect

    Solis, S. E.; Hernandez, J. A.; Rodriguez, A. O.; Tomasi, D.

    2008-08-11

    Arrays of antennas have been widely accepted for magnetic resonance imaging applications due to their high signal-to-noise ratio (SNR) over large volumes of interest. A new surface coil based on the magnetron tube and called slotted surface coil, has been recently introduced by our group. This coil design experimentally demonstrated a significant improvement over the circular-shaped coil when used in the receive-only mode. The slotted coils formed a two-sheet structure with a 90 deg. separation and each coil had 6 circular slots. Numerical simulations were performed using the finite element method for this coil design to study the behaviour of the array magnetic field. Then, we developed a two-coil array for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. In vitro images showed the feasibility of this coil array for standard pulses for high field magnetic resonance imaging.

  9. Tuning magnetic disorder in diluted magnetic semiconductors using high fields to 89 Tesla

    SciTech Connect

    Crooker, Scott A; Samarth, Nitin

    2008-01-01

    We describe recent and ongoing studies at the National High Magnetic Field Laboratory at Los Alamos using the new '100 Tesla Multi-Shot Magnet', which is presently delivering fields up to {approx}89 T during its commissioning. We discuss the first experiments performed in this magnet system, wherein the linewidth of low-temperature photoluminescence spectra was used to directly reveal the degree of magnetic alloy disorder 'seen' by excitons in single Zn{sub 0.80}Cd{sub 0.22}Mn{sub 0.08}Se quantum wells. The magnetic potential landscape in II-VI diluted magnetic semiconductors (DMS) is typically smoothed when the embedded Mn{sup 2+} spins align in an applied field. However, an important (but heretofore untested) prediction of current models of compositional disorder is that magnetic alloy fluctuations in many DMS compounds should increase again in very large magnetic fields approaching 100 T. We observed precisely this increase above {approx}70 T, in agreement with a simple model of magnetic alloy disorder.

  10. Examining the McGurk illusion using high-field 7 Tesla functional MRI.

    PubMed

    Szycik, Gregor R; Stadler, Jörg; Tempelmann, Claus; Münte, Thomas F

    2012-01-01

    In natural communication speech perception is profoundly influenced by observable mouth movements. The additional visual information can greatly facilitate intelligibility but incongruent visual information may also lead to novel percepts that neither match the auditory nor the visual information as evidenced by the McGurk effect. Recent models of audiovisual (AV) speech perception accentuate the role of speech motor areas and the integrative brain sites in the vicinity of the superior temporal sulcus (STS) for speech perception. In this event-related 7 Tesla fMRI study we used three naturally spoken syllable pairs with matching AV information and one syllable pair designed to elicit the McGurk illusion. The data analysis focused on brain sites involved in processing and fusing of AV speech and engaged in the analysis of auditory and visual differences within AV presented speech. Successful fusion of AV speech is related to activity within the STS of both hemispheres. Our data supports and extends the audio-visual-motor model of speech perception by dissociating areas involved in perceptual fusion from areas more generally related to the processing of AV incongruence.

  11. An efficient tensor transpose algorithm for multicore CPU, Intel Xeon Phi, and NVidia Tesla GPU

    NASA Astrophysics Data System (ADS)

    Lyakh, Dmitry I.

    2015-04-01

    An efficient parallel tensor transpose algorithm is suggested for shared-memory computing units, namely, multicore CPU, Intel Xeon Phi, and NVidia GPU. The algorithm operates on dense tensors (multidimensional arrays) and is based on the optimization of cache utilization on x86 CPU and the use of shared memory on NVidia GPU. From the applied side, the ultimate goal is to minimize the overhead encountered in the transformation of tensor contractions into matrix multiplications in computer implementations of advanced methods of quantum many-body theory (e.g., in electronic structure theory and nuclear physics). A particular accent is made on higher-dimensional tensors that typically appear in the so-called multireference correlated methods of electronic structure theory. Depending on tensor dimensionality, the presented optimized algorithms can achieve an order of magnitude speedup on x86 CPUs and 2-3 times speedup on NVidia Tesla K20X GPU with respect to the naïve scattering algorithm (no memory access optimization). The tensor transpose routines developed in this work have been incorporated into a general-purpose tensor algebra library (TAL-SH).

  12. Partial epilepsy: A pictorial review of 3 TESLA magnetic resonance imaging features

    PubMed Central

    Abud, Lucas Giansante; Thivard, Lionel; Abud, Thiago Giansante; Nakiri, Guilherme Seizem; dos Santos, Antonio Carlos; Dormont, Didier

    2015-01-01

    Epilepsy is a disease with serious consequences for patients and society. In many cases seizures are sufficiently disabling to justify surgical evaluation. In this context, Magnetic Resonance Imaging (MRI) is one of the most valuable tools for the preoperative localization of epileptogenic foci. Because these lesions show a large variety of presentations (including subtle imaging characteristics), their analysis requires careful and systematic interpretation of MRI data. Several studies have shown that 3 Tesla (T) MRI provides a better image quality than 1.5 T MRI regarding the detection and characterization of structural lesions, indicating that high-field-strength imaging should be considered for patients with intractable epilepsy who might benefit from surgery. Likewise, advanced MRI postprocessing and quantitative analysis techniques such as thickness and volume measurements of cortical gray matter have emerged and in the near future, these techniques will routinely enable more precise evaluations of such patients. Finally, the familiarity with radiologic findings of the potential epileptogenic substrates in association with combined use of higher field strengths (3 T, 7 T, and greater) and new quantitative analytical post-processing techniques will lead to improvements regarding the clinical imaging of these patients. We present a pictorial review of the major pathologies related to partial epilepsy, highlighting the key findings of 3 T MRI. PMID:26375569

  13. High resolution T2(*)-weighted Magnetic Resonance Imaging at 3 Tesla using PROPELLER-EPI.

    PubMed

    Krämer, Martin; Reichenbach, Jürgen R

    2014-05-01

    We report the application of PROPELLER-EPI for high resolution T2(*)-weighted imaging with sub-millimeter in-plane resolution on a clinical 3 Tesla scanner. Periodically rotated blades of a long-axis PROPELLER-EPI sequence were acquired with fast gradient echo readout and acquisition matrix of 320 × 50 per blade. Images were reconstructed by using 2D-gridding, phase and geometric distortion correction and compensation of resonance frequency drifts that occurred during extended measurements. To characterize these resonance frequency offsets, short FID calibration measurements were added to the PROPELLER-EPI sequence. Functional PROPELLER-EPI was performed with volunteers using a simple block design of right handed finger tapping. Results indicate that PROPELLER-EPI can be employed for fast, high resolution T2(*)-weighted imaging provided geometric distortions and possible resonance frequency drifts are properly corrected. Even small resonance frequency drifts below 10 Hz as well as non-corrected geometric distortions degraded image quality substantially. In the initial fMRI experiment image quality and signal-to-noise ratio was sufficient for obtaining high resolution functional activation maps.

  14. A Novel X-ray Diffractometer for the Florida Split Coil 25 Tesla Magnet

    NASA Astrophysics Data System (ADS)

    Wang, Shengyu; Kovalev, Alexey; Suslov, Alexey; Siegrist, Theo

    2014-03-01

    At National High Magnetic Field Laboratory (NHMFL), we are developing a unique X-ray diffractometer for the 25 Tesla Florida Split Coil Magnet for scattering experiments under extremely high static magnetic fields. The X-ray source is a sealed tube (copper or molybdenum anode), connected to the magnet by an evacuated beam tunnel. The detectors are either an image plate or a silicon drift detector, with the data acquisition system based on LabVIEW. Our preliminary experimental results showed that the performance of the detector electronics and the X-ray generator is reliable in the fringe magnetic fields produced at the highest field of 25 T. Using this diffractometer, we will make measurements on standard samples, such as LaB6, Al2O3 and Si, to calibrate the diffraction system. Magnetic samples, such as single crystal HoMnO3 and stainless steel 301 alloys will be measured subsequently. The addition of X-ray diffraction to the unique split coil magnet will significantly expand the NHMFL experimental capabilities. Therefore, external users will be able to probe spin - lattice interactions at static magnetic fields up to 25T. This project is supported by NSF-DMR Award No.1257649. NHMFL is supported by NSF Cooperative Agreement No. DMR-1157490, the State of Florida, and the U.S. DoE.

  15. CFD Design and Analysis of a Passively Suspended Tesla Pump Left Ventricular Assist Device

    PubMed Central

    Medvitz, Richard B.; Boger, David A.; Izraelev, Valentin; Rosenberg, Gerson; Paterson, Eric G.

    2012-01-01

    This paper summarizes the use of computational fluid dynamics (CFD) to design a novelly suspended Tesla LVAD. Several design variants were analyzed to study the parameters affecting device performance. CFD was performed at pump speeds of 6500, 6750 and 7000 RPM and at flow rates varying from 3 to 7 liter-per-minute (LPM). The CFD showed that shortening the plates nearest the pump inlet reduced the separations formed beneath the upper plate leading edges and provided a more uniform flow distribution through the rotor gaps, both of which positively affected the device hydrodynamic performance. The final pump design was found to produce a head rise of 77 mmHg with a hydraulic efficiency of 16% at the design conditions of 6 LPM throughflow and a 6750 RPM rotation rate. To assess the device hemodynamics the strain rate fields were evaluated. The wall shear stresses demonstrated that the pump wall shear stresses were likely adequate to inhibit thrombus deposition. Finally, an integrated field hemolysis model was applied to the CFD results to assess the effects of design variation and operating conditions on the device hemolytic performance. PMID:21595722

  16. Comparison Between Eight- and Sixteen-Channel TEM Transceive Arrays for Body Imaging at 7 Tesla

    PubMed Central

    Snyder, CJ; DelaBarre, L; Moeller, S; Tian, J; Akgun, C; Van De Moortele, P-F; Bolan, PJ; Ugurbil, K; Vaughan, JT; Metzger, GJ

    2011-01-01

    Eight- and sixteen-channel transceive stripline/TEM body arrays were compared at 7 tesla (297 MHz) both in simulation and experimentally. Despite previous demonstrations of similar arrays for use in body applications, a quantitative comparison of the two configurations has not been undertaken to date. Results were obtained on a male pelvis for assessing transmit, SNR and parallel imaging performance and to evaluate local power deposition versus transmit B1 (B1+). All measurements and simulations were conducted after performing local B1+ phase shimming in the region of the prostate. Despite the additional challenges of decoupling immediately adjacent coils, the sixteen-channel array demonstrated improved or nearly equivalent performance to the eight-channel array based on the evaluation criteria. Experimentally, transmit performance and SNR were 22% higher for the sixteen-channel array while significantly increased reduction factors were achievable in the left-right direction for parallel imaging. Finite-difference time-domain simulations demonstrated similar results with respect to transmit and parallel imaging performance, however a higher transmit efficiency advantage of 33% was predicted. Simulations at both 3T and 7T verified the expected parallel imaging improvements with increasing field strength and showed that, for a specific B1+ shimming strategy employed, the sixteen-channel array exhibited lower local and global SAR for a given B1+. PMID:22102483

  17. Test Results of HD1b, an upgraded 16 Tesla Nb3Sn DipoleMagnet

    SciTech Connect

    Lietzke, A.F.; Bartlett, S.E.; Bish, P.; Caspi, S.; Dietderich,D.; Ferracin, P.; Gourlay, S.; Hafalia, A.R.; Hannaford, C.R.; Higley,H.; Lau, W.; Liggins, N.; Mattafirri, S.; Nyman, M.; Sabbi, G.; Scanlan,R.; Swanson, J.

    2005-04-16

    The Superconducting Magnet Group at Lawrence Berkeley National Laboratory has been developing high-field, brittle-superconductor, accelerator magnet technology, in which the conductor's support system can significantly impact conductor performance (as well as magnet training). A recent H-dipole coil test (HD1) achieved a peak bore-field of 16 Tesla, using two, flat-racetrack, double-layer Nb{sub 3}Sn coils. However, its 4.5 K training was slow, with an erratic plateau at {approx}92% of its un-degraded ''short-sample'' expectation ({approx}16.6 T). Quench-origins correlated with regions where low conductor pre-stress had been expected (3-D FEM predictions and variations in 300 K coil-size). The coils were re-assembled with minor coil-support changes and re-tested as ''HD1b'', with a 185 MPa average pre-stress (30 MPa higher than HD1, with a 15-20 MPa pole-turn margin expected at 17 T). Training started higher (15.1 T), and quickly reached a stable, negligibly higher plateau at 16 T. After a thermal cycle, training started at 15.4 T, but peaked at 15.8 T, on the third attempt, before degrading to a 15.7 T plateau. The temperature dependence of this plateau was explored in a sub-atmospheric LHe bath to 3.0 K. Magnet performance data for both thermal cycles is presented and discussed, along with issues for future high-field accelerator magnet development.

  18. Prostate cancer detection using multiparametric 3 – tesla MRI and fusion biopsy: preliminary results

    PubMed Central

    Mussi, Thais Caldara; Garcia, Rodrigo Gobbo; de Queiroz, Marcos Roberto Gomes; Lemos, Gustavo Caserta; Baroni, Ronaldo Hueb

    2016-01-01

    ABSTRACT Objective: To evaluate the diagnostic efficacy of transrectal ultrasonography (US) biopsy with imaging fusion using multiparametric (mp) magnetic resonance imaging (MRI) in patients with suspicion of prostate cancer (PCa), with an emphasis on clinically significant tumors according to histological criteria. Materials and Methods: A total of 189 consecutive US/MRI fusion biopsies were performed obtaining systematic and guided samples of suspicious areas on mpMRI using a 3 Tesla magnet without endorectal coil. Clinical significance for prostate cancer was established based on Epstein criteria. Results: In our casuistic, the average Gleason score was 7 and the average PSA was 5.0ng/mL. Of the 189 patients that received US/MRI biopsies, 110 (58.2%) were positive for PCa. Of those cases, 88 (80%) were clinically significant, accounting for 46.6% of all patients. We divided the MRI findings into 5 Likert scales of probability of having clinically significant PCa. The positivity of US/MRI biopsy for clinically significant PCa was 0%, 17.6% 23.5%, 53.4% and 84.4% for Likert scores 1, 2, 3, 4 and 5, respectively. There was a statistically significant difference in terms of biopsy results between different levels of suspicion on mpMRI and also when biopsy results were divided into groups of clinically non-significant versus clinically significant between different levels of suspicion on mpMRI (p-value <0.05 in both analyzes). Conclusion: We found that there is a significant difference in cancer detection using US/MRI fusion biopsy between low-probability and intermediate/high probability Likert scores using mpMRI. PMID:27532112

  19. High resolution MRI anatomy of the cat brain at 3 Tesla

    PubMed Central

    Gray-Edwards, Heather L.; Salibi, Nouha; Josephson, Eleanor M.; Hudson, Judith A.; Cox, Nancy R.; Randle, Ashley N.; McCurdy, Victoria J.; Bradbury, Allison M.; Wilson, Diane U.; Beyers, Ronald J.; Denney, Thomas S.; Martin, Douglas R.

    2014-01-01

    Background Feline models of neurologic diseases, such as lysosomal storage diseases, leukodystrophies, Parkinson’s disease, stroke and NeuroAIDS, accurately recreate many aspects of human disease allowing for comparative study of neuropathology and the testing of novel therapeutics. Here we describe in vivo visualization of fine structures within the feline brain that were previously only visible post mortem. New Method 3 Tesla MR images were acquired using T1-weighted (T1w) 3D magnetization-prepared rapid gradient echo (MPRAGE) sequence (0.4mm isotropic resolution) and T2-weighted (T2w) turbo spin echo (TSE) images (0.3×0.3×1 mm3 resolution). Anatomic structures were identified based on feline and canine histology. Results T2w high resolution MR images with detailed structural identification are provided in transverse, sagittal and dorsal planes. T1w MR images are provided electronically in three dimensions for unrestricted spatial evaluation. Comparison with Existing Methods Many areas of the feline brain previously unresolvable on MRI are clearly visible in three orientations, including the dentate, interpositus and fastigial cerebellar nuclei, cranial nerves, lateral geniculate nucleus, optic radiation, cochlea, caudal colliculus, temporal lobe, precuneus, spinocerebellar tract, vestibular nuclei, reticular formation, pyramids and rostral and middle cerebral arteries. Additionally, the feline brain is represented in 3 dimensions for the first time. Conclusions These data establish normal appearance of detailed anatomical structures of the feline brain, which provide reference when evaluating neurologic disease or testing efficacy of novel therapeutics in animal models. PMID:24525327

  20. A 0.5 Tesla Transverse-Field Alternating Magnetic Field Demagnetizer

    NASA Astrophysics Data System (ADS)

    Schillinger, W. E.; Morris, E. R.; Finn, D. R.; Coe, R. S.

    2015-12-01

    We have built an alternating field demagnetizer that can routinely achieve a maximum field of 0.5 Tesla. It uses an amorphous magnetic core with an air-cooled coil. We have started with a 0.5 T design, which satisfies most of our immediate needs, but we can certainly achieve higher fields. In our design, the magnetic field is transverse to the bore and uniform to 1% over a standard (25 mm) paleomagnetic sample. It is powered by a 1 kW power amplifier and is compatible with our existing sample handler for automated demagnetization and measurement (Morris et al., 2009). It's much higher peak field has enabled us to completely demagnetize many of the samples that previously we could not with commercial equipment. This capability is especially needed for high-coercivity sedimentary and igneous rocks that contain magnetic minerals that alter during thermal demagnetization. It will also enable detailed automated demagnetization of high coercivity phases in extraterrestrial samples, such as native iron, iron-alloy and sulfide minerals that are common in lunar rocks and meteorites. Furthermore, it has opened the door for us to use the rock-magnetic technique of component analysis, using coercivity distributions derived from very detailed AF demagnetization of NRM and remanence produced in the laboratory to characterize the magnetic mineralogy of sedimentary rocks. In addition to the many benefits this instrument has brought to our own research, a much broader potential impact is to replace the transverse coils in automated AF demagnetization systems, which typically are limited to peak fields around 0.1 T.

  1. Canine Body Composition Quantification using 3 Tesla Fat-Water MRI

    PubMed Central

    Gifford, Aliya; Kullberg, Joel; Berglund, Johan; Malmberg, Filip; Coate, Katie C.; Williams, Phillip E.; Cherrington, Alan D.; Avison, Malcolm J.; Welch, E. Brian

    2013-01-01

    Purpose To test the hypothesis that a whole-body fat-water MRI (FWMRI) protocol acquired at 3 Tesla combined with semi-automated image analysis techniques enables precise volume and mass quantification of adipose, lean and bone tissue depots that agree with static scale mass and scale mass changes in the context of a longitudinal study of large-breed dogs placed on an obesogenic high-fat, high-fructose diet. Materials and Methods Six healthy adult male dogs were scanned twice, at weeks 0 (baseline) and 4, of the dietary regiment. FWMRI-derived volumes of adipose tissue (total, visceral, and subcutaneous), lean tissue, and cortical bone were quantified using a semi-automated approach. Volumes were converted to masses using published tissue densities. Results FWMRI-derived total mass corresponds with scale mass with a concordance correlation coefficient of 0.931 (95% confidence interval = [0.813, 0.975]), and slope and intercept values of 1.12 and −2.23 kg respectively. Visceral, subcutaneous and total adipose tissue masses increased significantly from weeks 0 to 4, while neither cortical bone nor lean tissue masses changed significantly. This is evidenced by a mean percent change of 70.2% for visceral, 67.0% for subcutaneous, and 67.1% for total adipose tissue. Conclusion FWMRI can precisely quantify and map body composition with respect to adipose, lean and bone tissue depots. The described approach provides a valuable tool to examine the role of distinct tissue depots in an established animal model of human metabolic disease. PMID:23596090

  2. Clinical Evaluation of Stereotactic Target Localization Using 3-Tesla MRI for Radiosurgery Planning

    SciTech Connect

    MacFadden, Derek; Zhang Beibei; Brock, Kristy K.; Hodaie, Mojgan; Laperriere, Normand; Schwartz, Michael; Tsao, May; Stainsby, Jeffrey; Lockwood, Gina; Mikulis, David; Menard, Cynthia

    2010-04-15

    Purpose: Increasing the magnetic resonance imaging (MRI) field strength can improve image resolution and quality, but concerns remain regarding the influence on geometric fidelity. The objectives of the present study were to spatially investigate the effect of 3-Tesla (3T) MRI on clinical target localization for stereotactic radiosurgery. Methods and Materials: A total of 39 patients were enrolled in a research ethics board-approved prospective clinical trial. Imaging (1.5T and 3T MRI and computed tomography) was performed after stereotactic frame placement. Stereotactic target localization at 1.5T vs. 3T was retrospectively analyzed in a representative cohort of patients with tumor (n = 4) and functional (n = 5) radiosurgical targets. The spatial congruency of the tumor gross target volumes was determined by the mean discrepancy between the average gross target volume surfaces at 1.5T and 3T. Reproducibility was assessed by the displacement from an averaged surface and volume congruency. Spatial congruency and the reproducibility of functional radiosurgical targets was determined by comparing the mean and standard deviation of the isocenter coordinates. Results: Overall, the mean absolute discrepancy across all patients was 0.67 mm (95% confidence interval, 0.51-0.83), significantly <1 mm (p < .010). No differences were found in the overall interuser target volume congruence (mean, 84% for 1.5T vs. 84% for 3T, p > .4), and the gross target volume surface mean displacements were similar within and between users. The overall average isocenter coordinate discrepancy for the functional targets at 1.5T and 3T was 0.33 mm (95% confidence interval, 0.20-0.48), with no patient-specific differences between the mean values (p >.2) or standard deviations (p >.1). Conclusion: Our results have provided clinically relevant evidence supporting the spatial validity of 3T MRI for use in stereotactic radiosurgery under the imaging conditions used.

  3. Influence of 1.5-Tesla intraoperative MR imaging on surgical decision making.

    PubMed

    Hall, W A; Liu, H; Maxwell, R E; Truwit, C L

    2003-01-01

    To determine the frequency that high-field magnetic resonance (MR) imaging sequences influenced surgical decision making during intraoperative MR-guided surgery. From January 1997 to February 2001, 346 MR-guided procedures were performed using a 1.5-Tesla MR system (NT-ACS, Philips Medical Systems). This system can perform functional MR imaging (fMRI), diffusion weighted imaging (DWI), MR spectroscopy (MRS), MR angiography (MRA), and MR venography (MRV) in addition to T1-weighted, T2-weighted, and turbo FLAIR (fluid-attenuated inversion recovery) imaging. FMRI was used to determine areas of brain activation for language, motor function, and memory. DWI was utilized after tumor resection to exclude cerebral ischemia or infarction. MRS was obtained to identify areas of elevated choline that were suspected to correlate with tumor presence. MRA and MRV localized vascular structures adjacent to tumors prior to resection. The intraoperative procedures performed included 140 brain biopsies of which 82 utilized a trajectory guide and prospective stereotaxy. MRS was used in 42 biopsies (30%), of which 29 had turbo spectroscopic imaging (TSI) and 21 had single voxel spectroscopy (SVS). In all biopsy cases, diagnostic tissue was obtained. There were 103 tumor resections of which 18 (17%) had MRS. Functional MRI was used in 17 cases; 3 biopsies (2%) and 14 planned resections (14%). Speech function was localized in 3 cases, memory function in 3, and motor function in 11. In one case where the motor function of the tongue was intimately involved with a low-grade glioma, resection was not attempted. DWI was used in less than 10% of tumor resections. MRA and MRV were performed in 3 (3%) and 2 (2%) of tumor resections, respectively. The imaging capabilities (i.e., fMRI, DWI, MRA, MRV) associated with high-field intraoperative MR influenced surgical decision making primarily for tumor resections. MRS influenced target selection during brain biopsy.

  4. Bloch-Siegert B1+-Mapping for Human Cardiac 31P-MRS at 7 Tesla

    PubMed Central

    Clarke, William T.; Robson, Matthew D.; Rodgers, Christopher T.

    2016-01-01

    Purpose Phosphorus MR spectroscopy (31P-MRS) is a powerful tool for investigating tissue energetics in vivo. Cardiac 31P-MRS is typically performed using surface coils that create an inhomogeneous excitation field across the myocardium. Accurate measurements of B1+ (and hence flip angle) are necessary for quantitative analysis of 31P-MR spectra. We demonstrate a Bloch-Siegert B1+-mapping method for this purpose. Theory and Methods We compare acquisition strategies for Bloch-Siegert B1+-mapping when there are several spectral peaks. We optimize a Bloch-Siegert sensitizing (Fermi) pulse for cardiac 31P-MRS at 7 Tesla (T) and apply it in a three-dimensional (3D) chemical shift imaging sequence. We validate this in phantoms and skeletal muscle (against a dual-TR method) and present the first cardiac 31P B1+-maps at 7T. Results The Bloch-Siegert method correlates strongly (Pearson’s r = 0.90 and 0.84) and has bias <25 Hz compared with a multi-TR method in phantoms and dual-TR method in muscle. Cardiac 3D B1+-maps were measured in five normal volunteers. B1+ maps based on phosphocreatine and alpha-adenosine-triphosphate correlated strongly (r = 0.62), confirming that the method is T1 insensitive. Conclusion The 3D 31P Bloch-Siegert B1+-mapping is consistent with reference methods in phantoms and skeletal muscle. It is the first method appropriate for 31P B1+-mapping in the human heart at 7T. PMID:26509652

  5. Colonoscopy detects significantly more flat adenomas than 3-tesla magnetic resonance colonography: a pilot trial

    PubMed Central

    Hüneburg, Robert; Kukuk, Guido; Nattermann, Jacob; Endler, Christoph; Penner, Arndt-Hendrik; Wolter, Karsten; Schild, Hans; Strassburg, Christian; Sauerbruch, Tilman; Schmitz, Volker; Willinek, Winfried

    2016-01-01

    Background and study aims: Colorectal cancer (CRC) is one of the most common cancers worldwide, and several efforts have been made to reduce its occurrence or severity. Although colonoscopy is considered the gold standard in CRC prevention, it has its disadvantages: missed lesions, bleeding, and perforation. Furthermore, a high number of patients undergo this procedure even though no polyps are detected. Therefore, an initial screening examination may be warranted. Our aim was to compare the adenoma detection rate of magnetic resonance colonography (MRC) with that of optical colonoscopy. Patients and methods: A total of 25 patients with an intermediate risk for CRC (17 men, 8 women; mean age 57.6, standard deviation 11) underwent MRC with a 3.0-tesla magnet, followed by colonoscopy. The endoscopist was initially blinded to the results of MRC and unblinded immediately after examining the distal rectum. Following endoscopic excision, the size, anatomical localization, and appearance of all polyps were described according to the Paris classification. Results: A total of 93 lesions were detected during colonoscopy. These included a malignant infiltration of the transverse colon due to gastric cancer in 1 patient, 28 adenomas in 10 patients, 19 hyperplastic polyps in 9 patients, and 45 non-neoplastic lesions. In 5 patients, no lesion was detected. MRC detected significantly fewer lesions: 1 adenoma (P = 0.001) and 1 hyperplastic polyp (P = 0.004). The malignant infiltration was seen with both modalities. Of the 28 adenomas, 23 (82 %) were 5 mm or smaller; only 4 adenomas 10 mm or larger (14 %) were detected. Conclusion: MRC does not detect adenomas sufficiently independently of the location of the lesion. Even advanced lesions were missed. Therefore, colonoscopy should still be considered the current gold standard, even for diagnostic purposes. PMID:26878043

  6. Axonal diameter and density estimated with 7-Tesla hybrid diffusion imaging in transgenic Alzheimer rats

    NASA Astrophysics Data System (ADS)

    Daianu, Madelaine; Jacobs, Russell E.; Town, Terrence; Thompson, Paul M.

    2016-03-01

    Diffusion-weighted MR imaging (DWI) is a powerful tool to study brain tissue microstructure. DWI is sensitive to subtle changes in the white matter (WM), and can provide insight into abnormal brain changes in diseases such as Alzheimer's disease (AD). In this study, we used 7-Tesla hybrid diffusion imaging (HYDI) to scan 3 transgenic rats (line TgF344-AD; that model the full clinico-pathological spectrum of the human disease) ex vivo at 10, 15 and 24 months. We acquired 300 DWI volumes across 5 q-sampling shells (b=1000, 3000, 4000, 8000, 12000 s/mm2). From the top three b-value shells with highest signal-to-noise ratios, we reconstructed markers of WM disease, including indices of axon density and diameter in the corpus callosum (CC) - directly quantifying processes that occur in AD. As expected, apparent anisotropy progressively decreased with age; there were also decreases in the intra- and extra-axonal MR signal along axons. Axonal diameters were larger in segments of the CC (splenium and body, but not genu), possibly indicating neuritic dystrophy - characterized by enlarged axons and dendrites as previously observed at the ultrastructural level (see Cohen et al., J. Neurosci. 2013). This was further supported by increases in MR signals trapped in glial cells, CSF and possibly other small compartments in WM structures. Finally, tractography detected fewer fibers in the CC at 10 versus 24 months of age. These novel findings offer great potential to provide technical and scientific insight into the biology of brain disease.

  7. Ultrahigh-Field MRI in Human Ischemic Stroke – a 7 Tesla Study

    PubMed Central

    Bauer, Miriam; Stengl, Katharina L.; Mutke, Matthias A.; Tovar-Martinez, Elena; Wuerfel, Jens; Endres, Matthias; Niendorf, Thoralf; Sobesky, Jan

    2012-01-01

    Introduction Magnetic resonance imaging (MRI) using field strengths up to 3 Tesla (T) has proven to be a powerful tool for stroke diagnosis. Recently, ultrahigh-field (UHF) MRI at 7 T has shown relevant diagnostic benefits in imaging of neurological diseases, but its value for stroke imaging has not been investigated yet. We present the first evaluation of a clinically feasible stroke imaging protocol at 7 T. For comparison an established stroke imaging protocol was applied at 3 T. Methods In a prospective imaging study seven patients with subacute and chronic stroke were included. Imaging at 3 T was immediately followed by 7 T imaging. Both protocols included T1-weighted 3D Magnetization-Prepared Rapid-Acquired Gradient-Echo (3D-MPRAGE), T2-weighted 2D Fluid Attenuated Inversion Recovery (2D-FLAIR), T2-weighted 2D Fluid Attenuated Inversion Recovery (2D-T2-TSE), T2* weighted 2D Fast Low Angle Shot Gradient Echo (2D-HemoFLASH) and 3D Time-of-Flight angiography (3D-TOF). Results The diagnostic information relevant for clinical stroke imaging obtained at 3 T was equally available at 7 T. Higher spatial resolution at 7 T revealed more anatomical details precisely depicting ischemic lesions and periinfarct alterations. A clear benefit in anatomical resolution was also demonstrated for vessel imaging at 7 T. RF power deposition constraints induced scan time prolongation and reduced brain coverage for 2D-FLAIR, 2D-T2-TSE and 3D-TOF at 7 T versus 3 T. Conclusions The potential of 7 T MRI for human stroke imaging is shown. Our pilot study encourages a further evaluation of the diagnostic benefit of stroke imaging at 7 T in a larger study. PMID:22701525

  8. Single-Bunch Electron Cloud Effects in the GLC/NLC, US-Cold and TESLA Low Emittance Transport Lines

    SciTech Connect

    Bates, D.

    2005-04-12

    This paper examines the severity of the electron cloud effects in the Low Emittance Transport (LET) of linear colliders including the Bunch-Compressor System (BCS) and Beam Delivery System (BDS). We examine the electron cloud effects in the normal-conducting GLC/NLC or X-Band, and the super-conducting US-Cold and TESLA linear collider designs through the use of specially developed computer simulation codes. An estimate of the critical cloud density is given for the BDS and BCS of the X-Band collider.

  9. Cavity digital control testing system by Simulink step operation method for TESLA linear accelerator and free electron laser

    NASA Astrophysics Data System (ADS)

    Czarski, Tomasz; Romaniuk, Ryszard S.; Pozniak, Krzysztof T.; Simrock, Stefan

    2004-07-01

    The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced in this paper. The FPGA -- Field Programmable Gate Array technology has been implemented for digital controller stabilizing cavity field gradient. The cavity SIMULINK model has been applied to test the hardware controller. The step operation method has been developed for testing the FPGA device coupled to the SIMULINK model of the analog real plant. The FPGA signal processing has been verified according to the required algorithm of the reference MATLAB controller. Some experimental results have been presented for different cavity operational conditions.

  10. 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer: A National Resource for Ultrahigh Resolution Mass Analysis.

    PubMed

    Hendrickson, Christopher L; Quinn, John P; Kaiser, Nathan K; Smith, Donald F; Blakney, Greg T; Chen, Tong; Marshall, Alan G; Weisbrod, Chad R; Beu, Steven C

    2015-09-01

    We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (m/Δm(50%)) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users. PMID:26091892

  11. Magnetic torque study of Weyl semimetal compounds TaP and NbP up to 45 Tesla

    NASA Astrophysics Data System (ADS)

    Li, Gang; Asaba, Tomoya; Tinsman, Colin; Yu, Fan; Lawson, Benjamin; Chen, Yulin; Li, Lu

    Weyl semimetal is a recently proposed new state in condensed matter physics, in which the bulk bands could have three dimensional linear dispersion but the degeneracy at the cross point is lifted into a pair of Weyl points with opposite chirality. Among the predicted candidates, Tantalum monophorspide (TaP) and Niobium monophorspide (NbP) have the simplest composition and do not require extrinsic tuning. Photoemission data is accumulating and the unique Fermi-arc surface state is observed. Magnetotransport experiments has shown highly anisotropic magnetoresistance and quantum oscillations has been observed. Because both linear dispersive bands and conventional bands exist in these materials, a detailed study of the electronic strucuture of the bulk is highly desirable. We use torque magnetometry to study quantum oscillations of TaP and NbP down to 300 mK, and up to 45 Tesla, with focus on the angular dependence of oscillation frequencies. Our comparison shows clear difference in geometry of different bulk bands in these materials. Besides, a discussion will be made on high field torque data since 45 Tesla is high enough to push several of the bands into quantum limit.

  12. Automatic 3D Segmentation and Quantification of Lenticulostriate Arteries from High-Resolution 7 Tesla MRA Images.

    PubMed

    Wei Liao; Rohr, Karl; Chang-Ki Kang; Zang-Hee Cho; Worz, Stefan

    2016-01-01

    We propose a novel hybrid approach for automatic 3D segmentation and quantification of high-resolution 7 Tesla magnetic resonance angiography (MRA) images of the human cerebral vasculature. Our approach consists of two main steps. First, a 3D model-based approach is used to segment and quantify thick vessels and most parts of thin vessels. Second, remaining vessel gaps of the first step in low-contrast and noisy regions are completed using a 3D minimal path approach, which exploits directional information. We present two novel minimal path approaches. The first is an explicit approach based on energy minimization using probabilistic sampling, and the second is an implicit approach based on fast marching with anisotropic directional prior. We conducted an extensive evaluation with over 2300 3D synthetic images and 40 real 3D 7 Tesla MRA images. Quantitative and qualitative evaluation shows that our approach achieves superior results compared with a previous minimal path approach. Furthermore, our approach was successfully used in two clinical studies on stroke and vascular dementia.

  13. 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer: A National Resource for Ultrahigh Resolution Mass Analysis.

    PubMed

    Hendrickson, Christopher L; Quinn, John P; Kaiser, Nathan K; Smith, Donald F; Blakney, Greg T; Chen, Tong; Marshall, Alan G; Weisbrod, Chad R; Beu, Steven C

    2015-09-01

    We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (m/Δm(50%)) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users.

  14. Fiber-optic link for the RF phase reference distribution system for the XFEL and TESLA projects

    NASA Astrophysics Data System (ADS)

    Czuba, Krzysztof; Eints, Frank; Felber, Matthias; Simrock, Stefan

    2005-02-01

    The UV Free-Electron Laser (UVFEL) and The TeV-Energy Superconducting Linear Accelerator (TESLA) projects will require phase synchronization of 0.1 ps short term (millisecond), 1 ps short term (minutes) and 10 ps long term (days). The stringent synchronization requirement of 10fs was given for the X-Ray Free- Electron Laser (XFEL). To fufill this requirement the XFEL may use a fiber laser as reference generator. But this requirement applies for a special location only, therefore the RF phase reference distribution system developed UVFEL and TESLA will also be used in the XFEL. The RF phase reference distribution system must deliver phase stable signals to hundreds of stations over a length of 33 km. Long, optical fiber based links are planned to be an important part of the entire distribution system. This paper describes the concept of a long optical link, with a feedback system suppressing long term drifts of the RF signal phase. Stability requirements are given and most important design issues affecting system performance are discussed. Finally, an experimental setup and measurement results demonstrating system performance is shown.

  15. Automatic 3D Segmentation and Quantification of Lenticulostriate Arteries from High-Resolution 7 Tesla MRA Images.

    PubMed

    Wei Liao; Rohr, Karl; Chang-Ki Kang; Zang-Hee Cho; Worz, Stefan

    2016-01-01

    We propose a novel hybrid approach for automatic 3D segmentation and quantification of high-resolution 7 Tesla magnetic resonance angiography (MRA) images of the human cerebral vasculature. Our approach consists of two main steps. First, a 3D model-based approach is used to segment and quantify thick vessels and most parts of thin vessels. Second, remaining vessel gaps of the first step in low-contrast and noisy regions are completed using a 3D minimal path approach, which exploits directional information. We present two novel minimal path approaches. The first is an explicit approach based on energy minimization using probabilistic sampling, and the second is an implicit approach based on fast marching with anisotropic directional prior. We conducted an extensive evaluation with over 2300 3D synthetic images and 40 real 3D 7 Tesla MRA images. Quantitative and qualitative evaluation shows that our approach achieves superior results compared with a previous minimal path approach. Furthermore, our approach was successfully used in two clinical studies on stroke and vascular dementia. PMID:26571526

  16. Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers.

    PubMed

    Theysohn, Jens M; Kraff, Oliver; Eilers, Kristina; Andrade, Dorian; Gerwig, Marcus; Timmann, Dagmar; Schmitt, Franz; Ladd, Mark E; Ladd, Susanne C; Bitz, Andreas K

    2014-01-01

    Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B0 (n = 20), 7 T in & out B0 (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.

  17. Vestibular Effects of a 7 Tesla MRI Examination Compared to 1.5 T and 0 T in Healthy Volunteers

    PubMed Central

    Theysohn, Jens M.; Kraff, Oliver; Eilers, Kristina; Andrade, Dorian; Gerwig, Marcus; Timmann, Dagmar; Schmitt, Franz; Ladd, Mark E.; Ladd, Susanne C.; Bitz, Andreas K.

    2014-01-01

    Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or “postural instability” even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B0 (n = 20), 7 T in & out B0 (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or “over-compensation” of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role. PMID:24658179

  18. Support system design incorporating carbon/epoxy tension straps for a four tesla, one meter bore, MRI magnet

    SciTech Connect

    Watts, L.C.; Boulios, K.; Hartwig, K.T.

    1996-12-31

    The Texas Accelerator Center (TAC) constructed a four tesla, one meter bore, MRI magnet. Graphite/epoxy tension straps with thermal intercepts at 77 K and 20 K were used for a safe, efficient, and cost effective support system. Sixteen straps were used to support the 10,400 kg cold mass. TAC used a superferric concept to restrict the fringe field. With proper alignment the attractive forces between the magnet and iron are designed to cancel. Therefore, easy adjustment for proper positioning of the magnet, and strength to withstand the magnetic forces due to any misalignment are requirements of the support system. Since the MRI magnet was shipped by truck, the support system had to withstand dynamic loads. The design conduction heat load to the cold mass is 0.05 W. Details of the support system are presented.

  19. Recent electron-cloud simulation results for the main damping rings of the NLC and TESLA linear colliders

    SciTech Connect

    Pivi, M.; Raubenheimer, T.O.; Furman, M.A.

    2003-05-01

    In the beam pipe of the Main Damping Ring (MDR) of the Next Linear Collider (NLC), ionization of residual gases and secondary emission give rise to an electron-cloud which stabilizes to equilibrium after few bunch trains. In this paper, we present recent computer simulation results for the main features of the electron cloud at the NLC and preliminary simulation results for the TESLA main damping rings, obtained with the code POSINST that has been developed at LBNL, and lately in collaboration with SLAC, over the past 7 years. Possible remedies to mitigate the effect are also discussed. We have recently included the possibility to simulate different magnetic field configurations in our code including solenoid, quadrupole, sextupole and wiggler.

  20. Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac

    SciTech Connect

    Molloy, S.; Adolphsen, C.; Bane, K.; Frisch, J.; Li, Z.; May, J.; McCormick, D.; Smith, T.; Baboi, N.; Eddy, N.; Piccoli, L.; Rechenmacher, R.; Jones, R.; /Manchester U.

    2007-06-27

    Higher Order Modes (HOMs) excited by the passage of the beam through an accelerating cavity depend on the properties of both the cavity and the beam. It is possible, therefore, to draw conclusions on the inner geometry of the cavities based on observations of the properties of the HOM spectrum. A data acquisition system based on two 20 GS/s, 6 GHz scopes has been set up at the FLASH facility, DESY, in order to measure a significant fraction of the HOM spectrum predicted to be generated by the TESLA cavities used for the acceleration of its beam. The HOMs from a particular cavity at FLASH were measured under a range of known beam conditions. The dipole modes have been identified in the data. 3D simulations of different manufacturing errors have been made, and it has been shown that these simulations can predict the measured modes.

  1. A 4 Tesla Superconducting Magnet Developed for a 6 Circle Huber Diffractometer at the XMaS Beamline

    SciTech Connect

    Thompson, P. B. J.; Brown, S. D.; Bouchenoire, L.; Mannix, D.; Paul, D. F.; Lucas, C. A.; Kervin, J.; Cooper, M. J.; Arakawa, P.; Laughon, G.

    2007-01-19

    We report here on the development and testing of a 4 Tesla cryogen free superconducting magnet designed to fit within the Euler cradle of a 6 circle Huber diffractometer, allowing scattering in both the vertical and horizontal planes. The geometry of this magnet allows the field to be applied in three orientations. The first being along the beam direction, the second with the field transverse to the beam direction a horizontal plane and finally the field can be applied vertically with respect to the beam. The magnet has a warm bore and an open geometry of 180 deg. , allowing large access to reciprocal space. A variable temperature insert has been developed, which is capable of working down to a temperature of 1.7 K and operating over a wide range of angles whilst maintaining a temperature stability of a few mK. Initial ferromagnetic diffraction measurements have been carried out on single crystal Tb and Dy samples.

  2. MHD seawater thruster performance: A comparison of predictions with experimental results from a two Tesla test facility

    SciTech Connect

    Picologlou, B.F.; Doss, E.D.; Geyer, H.K. ); Sikes, W.C.; Ranellone, R.F. )

    1992-01-01

    A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate a design oriented MHD thruster performance computer code. The thruster performance code consists of a one-dimensional MHD hydrodynamic model coupled to a two-dimensional electrical model. The code includes major loss mechanisms affecting the performance of the thruster. Among these losses are the joule dissipation losses, frictional losses, electrical end losses, and single electrode potential losses. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rationale are discussed. Representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.

  3. A six-channel pediatric coil array for detection of children spinal pathologies by MRI at 1.5 Tesla

    NASA Astrophysics Data System (ADS)

    López Terrones, Marcos Alonso; Solís-Nájera, Sergio Enrique

    2014-11-01

    Nowadays, magnetic resonance (MR) in Mexico has become a standard technique for clinical imaging. Although most of the times the MR systems contain only coils oriented for adults. Radiologists use these coils for children studies due to the non-availability of pediatric coils. Image quality is decreased due to the low signal to noise ratio delivered to the system. The development of RF coils is always focused towards increasing SNR and optimizing the RF penetration into the sample. Moreover, spinal pathologies in children, which are an important topic in pediatric care, cover congenital and neuromuscular disorders that occur in childhood. In this work, the design of a dedicated six-channel coil for detection of spinal pathologies at 1.5 Tesla is addressed. Numerical electromagnetic simulations were performed in order to evaluate their magnetic field performance at (63.6 MHz) 1.5 Tesla. The magnetic field uniformity as well as the RF penetration depth of the coil configurations was evaluated in order to find the best/optimized coil array configuration. The coil is comprised of three rows, one with 4 coil elements and two with only one coil element. Phantom and in vivo images were acquired with the six-channel pediatric coil array. The phantom images agree with the simulated data. In vivo images acquired with the 6-channel pediatric coil array have shown very good penetration depth and homogeneity, which allow better image quality throughout the whole FOV. In addition, the parallel imaging capabilities of the array allow the acceleration of the experiments avoiding possible motion artifacts.

  4. Amide Proton Transfer Magnetic Resonance Imaging of Alzheimer's Disease at 3.0 Tesla: A Preliminary Study

    PubMed Central

    Wang, Rui; Li, Sa-Ying; Chen, Min; Zhou, Jin-Yuan; Peng, Dan-Tao; Zhang, Chen; Dai, Yong-Ming

    2015-01-01

    Background: Amide proton transfer (APT) imaging has recently emerged as an important contrast mechanism for magnetic resonance imaging (MRI) in the field of molecular and cellular imaging. The aim of this study was to evaluate the feasibility of APT imaging to detect cerebral abnormality in patients with Alzheimer's disease (AD) at 3.0 Tesla. Methods: Twenty AD patients (9 men and 11 women; age range, 67–83 years) and 20 age-matched normal controls (11 men and 9 women; age range, 63–82 years) underwent APT and traditional MRI examination on a 3.0 Tesla MRI system. The magnetic resonance ratio asymmetry (MTRasym) values at 3.5 ppm of bilateral hippocampi (Hc), temporal white matter regions, occipital white matter regions, and cerebral peduncles were measured on oblique axial APT images. MTRasym (3.5 ppm) values of the cerebral structures between AD patients and control subjects were compared with independent samples t-test. Controlling for age, partial correlation analysis was used to investigate the associations between mini-mental state examination (MMSE) and the various MRI measures among AD patients. Results: Compared with normal controls, MTRasym (3.5 ppm) values of bilateral Hc were significantly increased in AD patients (right 1.24% ± 0.21% vs. 0.83% ± 0.19%, left 1.18% ± 0.18% vs. 0.80%± 0.17%, t = 3.039, 3.328, P = 0.004, 0.002, respectively). MTRasym (3.5 ppm) values of bilateral Hc were significantly negatively correlated with MMSE (right r = −0.559, P = 0.013; left r = −0.461, P = 0.047). Conclusions: Increased MTRasym (3.5 ppm) values of bilateral Hc in AD patients and its strong correlations with MMSE suggest that APT imaging could potentially provide imaging biomarkers for the noninvasive molecular diagnosis of AD. PMID:25698192

  5. A six-channel pediatric coil array for detection of children spinal pathologies by MRI at 1.5 Tesla

    SciTech Connect

    López Terrones, Marcos Alonso; Solís-Nájera, Sergio Enrique

    2014-11-07

    Nowadays, magnetic resonance (MR) in Mexico has become a standard technique for clinical imaging. Although most of the times the MR systems contain only coils oriented for adults. Radiologists use these coils for children studies due to the non-availability of pediatric coils. Image quality is decreased due to the low signal to noise ratio delivered to the system. The development of RF coils is always focused towards increasing SNR and optimizing the RF penetration into the sample. Moreover, spinal pathologies in children, which are an important topic in pediatric care, cover congenital and neuromuscular disorders that occur in childhood. In this work, the design of a dedicated six-channel coil for detection of spinal pathologies at 1.5 Tesla is addressed. Numerical electromagnetic simulations were performed in order to evaluate their magnetic field performance at (63.6 MHz) 1.5 Tesla. The magnetic field uniformity as well as the RF penetration depth of the coil configurations was evaluated in order to find the best/optimized coil array configuration. The coil is comprised of three rows, one with 4 coil elements and two with only one coil element. Phantom and in vivo images were acquired with the six-channel pediatric coil array. The phantom images agree with the simulated data. In vivo images acquired with the 6-channel pediatric coil array have shown very good penetration depth and homogeneity, which allow better image quality throughout the whole FOV. In addition, the parallel imaging capabilities of the array allow the acceleration of the experiments avoiding possible motion artifacts.

  6. Analysis of the Tesla transformer operation at the first half-wave of the output voltage taking into account ohmic losses

    NASA Astrophysics Data System (ADS)

    Palchikov, E. I.; Ryabchun, A. M.

    2016-06-01

    The speed and efficiency of the Tesla transformer at the first half-wave of the output voltage are studied as a function of the Q factors of the circuits and their coupling factor. Calculated results and experimental data are considered. It is shown that for given Q factors, there is an optimal value of the coupling factor providing the highest efficiency, which can be calculated and for which designers should work.

  7. Combined 3 Tesla MRI Biomarkers Improve the Differentiation between Benign vs Malignant Single Ring Enhancing Brain Masses

    PubMed Central

    Salice, Simone; Esposito, Roberto; Ciavardelli, Domenico; delli Pizzi, Stefano; di Bastiano, Rossella; Tartaro, Armando

    2016-01-01

    Purpose To evaluate whether the combination of imaging biomarkers obtained by means of different 3 Tesla (3T) Magnetic Resonance Imaging (MRI) advanced techniques can improve the diagnostic accuracy in the differentiation between benign and malignant single ring-enhancing brain masses. Materials and Methods 14 patients presenting at conventional 3T MRI single brain mass with similar appearance as regard ring enhancement, presence of peri-lesional edema and absence of hemorrhage signs were included in the study. All lesions were histologically proven: 5 pyogenic abscesses, 6 glioblastomas, and 3 metastases. MRI was performed at 3 Tesla and included Diffusion Weighted Imaging (DWI), Dynamic Susceptibility Contrast -Perfusion Weighted Imaging (DSC-PWI), Magnetic Resonance Spectroscopy (MRS), and Diffusion Tensor Imaging (DTI). Imaging biomarkers derived by those advanced techniques [Cerebral Blood Flow (CBF), relative Cerebral Blood Volume (rCBV), relative Main Transit Time (rMTT), Choline (Cho), Creatine (Cr), Succinate, N-Acetyl Aspartate (NAA), Lactate (Lac), Lipids, relative Apparent Diffusion Coefficient (rADC), and Fractional Anisotropy (FA)] were detected by two experienced neuroradiologists in joint session in 4 areas: Internal Cavity (IC), Ring Enhancement (RE), Peri-Lesional edema (PL), and Contralateral Normal Appearing White Matter (CNAWM). Significant differences between benign (n = 5) and malignant (n = 9) ring enhancing lesions were tested with Mann-Withney U test. The diagnostic accuracy of MRI biomarkers taken alone and MRI biomarkers ratios were tested with Receiver Operating Characteristic (ROC) analysis with an Area Under the Curve (AUC) ≥ 0.9 indicating a very good diagnostic accuracy of the variable. Results Five MRI biomarker ratios achieved excellent accuracy: IC-rADC/PL-NAA (AUC = 1), IC-rADC/IC-FA (AUC = 0.978), RE-rCBV/RE-FA (AUC = 0.933), IC-rADC/RE-FA (AUC = 0.911), and IC-rADC/PL-FA (AUC = 0.911). Only IC-rADC achieved a very good

  8. Feasibility of Using Pseudo-Continuous Arterial Spin Labeling Perfusion in a Geriatric Population at 1.5 Tesla

    PubMed Central

    Sigurdsson, Sigurdur; Forsberg, Lars; Aspelund, Thor; van der Geest, Rob J.; van Buchem, Mark A.; Launer, Lenore J.; Gudnason, Vilmundur; van Osch, Matthias J.

    2015-01-01

    Objectives To evaluate the feasibility of using pseudo-continuous arterial spin labeling (pCASL) perfusion in a geriatric population at 1.5-Tesla. Materials and Methods In 17 participants (mean age 78.8±1.63 years) we assessed; 1) inter-session repeatability and reliability of resting state perfusion in 27 brain regions; 2) brain activation using finger-tapping as a means to evaluate the ability to detect flow differences; 3) reliability by comparing cerebral blood flow (CBF) with pCASL to CBF with phase contrast (PC-MR). Results The CBF (mean±standard deviation (SD)) for the whole brain grey matter (GM) was 40.6±8.4 and 41.4±8.7 ml/100g/min for the first and second scan respectively. The within-subject standard deviation (SDw), the repeatability index (RI) and intra-class correlation coefficient (ICC) across the 27 regions ranged from 1.1 to 7.9, 2.2 to 15.5 and 0.35 to 0.98 respectively. For whole brain GM the SDw, RI and ICC were 1.6, 3.2 and 0.96 respectively. The between-subject standard deviation (SDB) was larger than the SDw for all regions. Comparison of CBF at rest and activation on a voxel level showed significantly higher perfusion during finger tapping in the motor- and somatosensory regions. The mean CBF for whole brain GM was 40.6±8.4 ml/100g/min at rest and 42.6±8.6 ml/100g/min during activation. Finally the reliability of pCASL against the reference standard of PC-MR was high (ICC = 0.80). The mean CBF for whole brain measured with PC-MRI was 54.3±10.1 ml/100g/min and 38.3±7.8 ml/100g/min with pCASL. Conclusions The results demonstrate moderate to high levels of repeatability and reliability for most brain regions, comparable to what has been reported for younger populations. The performance of pCASL at 1.5-Tesla shows that region-specific perfusion measurements with this technique are feasible in studies of a geriatric population. PMID:26659363

  9. In vivo functional connectome of human brainstem nuclei of the ascending arousal, autonomic and motor systems by high spatial resolution 7 Tesla fMRI

    PubMed Central

    Bianciardi, Marta; Toschi, Nicola; Eichner, Cornelius; Polimeni, Jonathan R.; Setsompop, Kawin; Brown, Emery N.; Hamalainen, Matti S.; Rosen, Bruce R.; Wald, Lawrence L.

    2016-01-01

    Object To map the in vivo human functional connectivity of several brainstem nuclei with the rest of the brain by using seed-based correlation of ultra-high magnetic field functional magnetic resonance imaging (fMRI) data. Materials and Methods We used the recently developed template of 11 brainstem nuclei derived from multi-contrast structural MRI at 7 Tesla as seed regions to determine their connectivity to the rest of the brain. To achieve this, we utilized the increased contrast-to-noise ratio of 7 Tesla fMRI compared to 3 Tesla and the time efficient simultaneous multi-slice imaging to cover the brain with high spatial resolution (1.1 mm-isotropic nominal resolution) while maintaining a short repetition time (2.5 s). Results The delineated Pearson’s correlation-based functional connectivity diagrams (connectomes) of 11 brainstem nuclei of the ascending arousal, motor and autonomic systems from 12 controls are presented and discussed in the context of existing histology and animal work. Conclusion Considering that the investigated brainstem nuclei play a crucial role in several vital functions, the delineated preliminary connectomes might prove useful for future in vivo research and clinical studies of human brainstem function and pathology, including disorders of consciousness, sleep disorders, autonomic disorders, Parkinson’s disease and other motor disorders. PMID:27126248

  10. [Optimal imaging parameters and the advantage of cerebrospinal fluid flow image using time-spatial labeling inversion pulse at 3 tesla magnetic resonance imaging: comparison of image quality for 1.5 tesla magnetic resonance imaging].

    PubMed

    Ozasa, Masaya; Yahata, Seiji; Yoshida, Ayako; Takeyama, Mamoru; Eshima, Mitsuhiro; Shinohara, Maiko; Yamamoto, Takao; Abe, Kayoko

    2014-12-01

    Cerebrospinal fluid (CSF) imaging by time-spatial labeling inversion pulse (Time-SLIP) technique is labeled by CSF with a selective inversion recovery (IR) pulse as internal tracer, thus making it possible to visualize CSF dynamics non-invasively. The purpose of this study was to clarify labeled CSF signals during various black blood time to inversion (BBTI) values at 3 tesla (T) and 1.5 T magnetic resonance imaging (MRI) and to determine appropriate CSF imaging parameters at 3 T MRI in 10 healthy volunteers. To calculate optimal BBTI values, ROIs were set in untagged cerebral parenchyma and CSF on the image of the CSF flow from the aqueduct to the fourth ventricle in 1.5 T and 3 T MRI. Visual evaluation of CSF flow also was assessed with changes of matrix and echo time (TE) at 3 T MRI. The mean BBTI value at null point of untagged CSF in 3 T MRI was longer than that of 1.5 T. The MR conditions of the highest visual evaluation were FOV, 14 cm×14 cm; Matrix, 192×192; and TE, 117 ms. CSF imaging using Time-SLIP at 3 T MRI is expected visualization of CSF flow and clarification of CSF dynamics in more detail by setting the optimal conditions because 3 T MRI has the advantage of high contrast and high signal-to-noise ratio.

  11. Low-Temperature Dynamic Nuclear Polarization at 9.4 Tesla With a 30 Milliwatt Microwave Source

    PubMed Central

    Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2010-01-01

    Dynamic nuclear polarization (DNP) can provide large signal enhancements in nuclear magnetic resonance (NMR) by transfer of polarization from electron spins to nuclear spins. We discuss several aspects of DNP experiments at 9.4 Tesla (400 MHz resonant frequency for 1H, 264 GHz for electron spins in organic radicals) in the 7–80 K temperature range, using a 30 mW, frequency-tunable microwave source and a quasi-optical microwave bridge for polarization control and low-loss microwave transmission. In experiments on frozen glycerol/water doped with nitroxide radicals, DNP signal enhancements up to a factor of 80 are observed (relative to 1H NMR signals with thermal equilibrium spin polarization). The largest sensitivity enhancements are observed with a new triradical dopant, DOTOPA-TEMPO. Field modulation with a 10 G root-mean-squared amplitude during DNP increases the nuclear spin polarizations by up to 135%. Dependencies of 1H NMR signal amplitudes, nuclear spin relaxation times, and DNP build-up times on the dopant and its concentration, temperature, microwave power, and modulation frequency are reported and discussed. The benefits of low-temperature DNP can be dramatic: the 1H spin polarization is increased approximately 1000-fold at 7 K with DNP, relative to thermal polarization at 80 K. PMID:20392658

  12. Generating Long Scale-Length Plasma Jets Embedded in a Uniform, Multi-Tesla Magnetic-Field

    NASA Astrophysics Data System (ADS)

    Manuel, Mario; Kuranz, Carolyn; Rasmus, Alex; Klein, Sallee; Fein, Jeff; Belancourt, Patrick; Drake, R. P.; Pollock, Brad; Hazi, Andrew; Park, Jaebum; Williams, Jackson; Chen, Hui

    2013-10-01

    Collimated plasma jets emerge in many classes of astrophysical objects and are of great interest to explore in the laboratory. In many cases, these astrophysical jets exist within a background magnetic field where the magnetic pressure approaches the plasma pressure. Recent experiments performed at the Jupiter Laser Facility utilized a custom-designed solenoid to generate the multi-tesla fields necessary to achieve proper magnetization of the plasma. Time-gated interferometry, Schlieren imaging, and proton radiography were used to characterize jet evolution and collimation under varying degrees of magnetization. Experimental results will be presented and discussed. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840, by the National Laser User Facility Program, grant number DE-NA0000850, by the Predictive Sciences Academic Alliances Program in NNSA-ASC, grant number DEFC52-08NA28616, and by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.

  13. A high-resolution 7-Tesla fMRI dataset from complex natural stimulation with an audio movie.

    PubMed

    Hanke, Michael; Baumgartner, Florian J; Ibe, Pierre; Kaule, Falko R; Pollmann, Stefan; Speck, Oliver; Zinke, Wolf; Stadler, Jörg

    2014-01-01

    Here we present a high-resolution functional magnetic resonance (fMRI) dataset - 20 participants recorded at high field strength (7 Tesla) during prolonged stimulation with an auditory feature film ("Forrest Gump"). In addition, a comprehensive set of auxiliary data (T1w, T2w, DTI, susceptibility-weighted image, angiography) as well as measurements to assess technical and physiological noise components have been acquired. An initial analysis confirms that these data can be used to study common and idiosyncratic brain response patterns to complex auditory stimulation. Among the potential uses of this dataset are the study of auditory attention and cognition, language and music perception, and social perception. The auxiliary measurements enable a large variety of additional analysis strategies that relate functional response patterns to structural properties of the brain. Alongside the acquired data, we provide source code and detailed information on all employed procedures - from stimulus creation to data analysis. In order to facilitate replicative and derived works, only free and open-source software was utilized. PMID:25977761

  14. A high-resolution 7-Tesla fMRI dataset from complex natural stimulation with an audio movie

    PubMed Central

    Hanke, Michael; Baumgartner, Florian J.; Ibe, Pierre; Kaule, Falko R.; Pollmann, Stefan; Speck, Oliver; Zinke, Wolf; Stadler, Jörg

    2014-01-01

    Here we present a high-resolution functional magnetic resonance (fMRI) dataset – 20 participants recorded at high field strength (7 Tesla) during prolonged stimulation with an auditory feature film (“Forrest Gump”). In addition, a comprehensive set of auxiliary data (T1w, T2w, DTI, susceptibility-weighted image, angiography) as well as measurements to assess technical and physiological noise components have been acquired. An initial analysis confirms that these data can be used to study common and idiosyncratic brain response patterns to complex auditory stimulation. Among the potential uses of this dataset are the study of auditory attention and cognition, language and music perception, and social perception. The auxiliary measurements enable a large variety of additional analysis strategies that relate functional response patterns to structural properties of the brain. Alongside the acquired data, we provide source code and detailed information on all employed procedures – from stimulus creation to data analysis. In order to facilitate replicative and derived works, only free and open-source software was utilized. PMID:25977761

  15. BI-ground microstrip array coil vs. conventional microstrip array coil for mouse imaging at 7 tesla

    NASA Astrophysics Data System (ADS)

    Hernández, Ricardo; Terrones, M. A. López; Jakob, P. M.

    2012-10-01

    At high field strengths, the need for more efficient high frequency coils has grown. Since the radiation losses and the interaction between coil and sample increase proportionally to field strength, the quality factor (Q) and the sensitivity of the coil decrease as consequence of these negative effects. Since Zhang et al proposed in 2001 a new surface coil based on the microstrip transmission line for high frequency, different Tx-Rx phased arrays based on this concept have been already introduced in animal and whole body systems at high field strengths, each of them with different modifications in order to get better field homogeneity, SNR or isolation between coil elements in the array. All these arrays for animals systems have been built for rat imaging. One of these modifications is called BI-Ground Microstrip Array Coil (BIGMAC). The implementation of a smaller two-channel BIGMAC design for mouse imaging is studied and its performance compared to a two-channel conventional Microstrip array at 7 Tesla, the higher isolation by using BIGMAC elements in comparison with conventional Microstrip elements is shown in this work.

  16. Characterization of transceive surface element designs for 7 tesla magnetic resonance imaging of the prostate: radiative antenna and microstrip

    NASA Astrophysics Data System (ADS)

    Ipek, Ö.; Raaijmakers, A. J. E.; Klomp, D. W. J.; Lagendijk, J. J. W.; Luijten, P. R.; van den Berg, C. A. T.

    2012-01-01

    Ultra-high field magnetic resonance (⩾7 tesla) imaging (MRI) faces challenges with respect to efficient spin excitation and signal reception from deeply situated organs. Traditional radio frequency surface coil designs relying on near-field coupling are suboptimal at high field strengths. Better signal penetration can be obtained by designing a radiative antenna in which the energy flux is directed to the target location. In this paper, two different radiative antenna designs are investigated to be used as transceive elements, which employ different dielectric permittivities for the antenna substrate. Their transmit and receive performances in terms of B+1, local SAR (specific absorption rate) and SNR (signal-to-noise ratio) were compared using extensive electromagnetic simulations and MRI measurements with traditional surface microstrip coils. Both simulations and measurements demonstrated that the radiative element shows twofold gain in B+1 and SNR at 10 cm depth, and additionally a comparable SAR peak value. In terms of transmit performance, the radiative antenna with a dielectric permittivity of 37 showed a 24% more favorable local SAR10g avg/(B+1)2 ratio than the radiative antenna with a dielectric permittivity of 90. In receive, the radiative element with a dielectric permittivity of 90 resulted in a 20% higher SNR for shallow depths, but for larger depths this difference diminished compared to the radiative element with a dielectric permittivity of 37. Therefore, to image deep anatomical regions effectively, the radiative antenna with a dielectric permittivity of 37 is favorable.

  17. Reproducibility of Neurochemical Profile Quantification in Pregenual Cingulate, Anterior Midcingulate, and Bilateral Posterior Insular Subdivisions Measured at 3 Tesla

    PubMed Central

    de Matos, Nuno M. P.; Meier, Lukas; Wyss, Michael; Meier, Dieter; Gutzeit, Andreas; Ettlin, Dominik A.; Brügger, Mike

    2016-01-01

    The current report assessed measurement reproducibility of proton magnetic resonance spectroscopy at 3 Tesla in the left and right posterior insular, pregenual anterior cingulate, and anterior midcingulate cortices. Ten healthy male volunteers aged 21–30 years were tested at four different days, of which nine were included in the data analysis. Intra- and inter-subject variability of myo-inositol, creatine, glutamate, total-choline, total-N-acetylaspartate, and combined glutamine–glutamate were calculated considering the influence of movement parameters, age, daytime of measurements, and tissue composition. Overall mean intra-/inter-subject variability for all neurochemicals combined revealed small mean coefficients of variation across the four regions: 5.3/9.05% in anterior midcingulate, 6.6/8.84% in pregenual anterior cingulate, 7.3/10.00% in left posterior and 8.2/10.55% in right posterior insula. Head movement, tissue composition and day time revealed no significant explanatory variance contribution suggesting a negligible influence on the data. A strong correlation between Cramer–Rao Lower Bounds (a measure of fitting errors) and the mean intra-subject coefficients of variation (r = 0.799, p < 0.001) outlined the importance of low fitting errors in order to obtain robust and finally meaningful measurements. The present findings confirm proton magnetic resonance spectroscopy as a reliable tool to measure brain neurochemistry in small subregions of the human brain. PMID:27445745

  18. Reproducibility of Neurochemical Profile Quantification in Pregenual Cingulate, Anterior Midcingulate, and Bilateral Posterior Insular Subdivisions Measured at 3 Tesla.

    PubMed

    de Matos, Nuno M P; Meier, Lukas; Wyss, Michael; Meier, Dieter; Gutzeit, Andreas; Ettlin, Dominik A; Brügger, Mike

    2016-01-01

    The current report assessed measurement reproducibility of proton magnetic resonance spectroscopy at 3 Tesla in the left and right posterior insular, pregenual anterior cingulate, and anterior midcingulate cortices. Ten healthy male volunteers aged 21-30 years were tested at four different days, of which nine were included in the data analysis. Intra- and inter-subject variability of myo-inositol, creatine, glutamate, total-choline, total-N-acetylaspartate, and combined glutamine-glutamate were calculated considering the influence of movement parameters, age, daytime of measurements, and tissue composition. Overall mean intra-/inter-subject variability for all neurochemicals combined revealed small mean coefficients of variation across the four regions: 5.3/9.05% in anterior midcingulate, 6.6/8.84% in pregenual anterior cingulate, 7.3/10.00% in left posterior and 8.2/10.55% in right posterior insula. Head movement, tissue composition and day time revealed no significant explanatory variance contribution suggesting a negligible influence on the data. A strong correlation between Cramer-Rao Lower Bounds (a measure of fitting errors) and the mean intra-subject coefficients of variation (r = 0.799, p < 0.001) outlined the importance of low fitting errors in order to obtain robust and finally meaningful measurements. The present findings confirm proton magnetic resonance spectroscopy as a reliable tool to measure brain neurochemistry in small subregions of the human brain. PMID:27445745

  19. Visual language and handwriting movement: functional magnetic resonance imaging at 3 tesla during generation of ideographic characters.

    PubMed

    Matsuo, K; Kato, C; Tanaka, S; Sugio, T; Matsuzawa, M; Inui, T; Moriya, T; Glover, G H; Nakai, T

    2001-07-01

    A functional magnetic resonance imaging experiment at 3 tesla was performed to investigate the collaborative mechanism between visuospatial processing and motor execution in performing visual language generation tasks. Japanese Kanji, ideographic characters, were utilized to design tasks. The bilateral border portions between the inferior parietal lobule and the occipital lobe were involved during a Kanji puzzle task, which required subjects to combine several parts into a Kanji. The higher motor areas, such as the premotor areas and the pre-supplementary motor areas, were also activated bilaterally during the puzzle task. The parieto-occipital activation may be related to analysis of configuration or segmentation/integration of Kanji figures. Activation in the higher motor areas may be induced by cognitive components related to motor function to perform the visuospatial language task, such as intense reference for displayed characters and finding a proper character for puzzle solution. A collaborative mechanism in these areas may explain the effectiveness of tactile reading in letter recognition by patients with pure alexia or kinesthetic facilitation by Kanji users when recalling difficult Kanji.

  20. A novel computerized algorithm to detect microstructural brainstem pathology in Parkinson's disease using standard 3 Tesla MR imaging.

    PubMed

    Boelmans, Kai; Spies, Lothar; Sedlacik, Jan; Fiehler, Jens; Jahn, Holger; Gerloff, Christian; Münchau, Alexander

    2014-10-01

    Increased deposition of α-synuclein in Parkinson's disease (PD) is known to be prominent in the brainstem and discussed to be clinically relevant for motor and non-motor features. Whether structural magnetic resonance imaging is capable to detect degraded tissue microstructure caused by increased deposition of α-synuclein at this predilection site in PD remains unclear. We hypothesize that microstructural degradation in the brainstem leads to a reduced T1 contrast provoking standard tissue segmentation engines to misclassify tissue as additional grey matter in regions predominantly composed of white matter. High-resolution T1-weighted three-dimensional magnetization prepared rapid gradient echo (MPRAGE) imaging at 3 Tesla in fifty-two PD patients with mild-to-moderate disease severity and in forty age- and gender-matched healthy controls was performed. A dedicated computerized algorithm that comprises standard tissue segmentation in combination with a statistical test was set up that evaluates grey matter composition on voxel level. The algorithm detected a single significant cluster of voxels with enhanced grey matter (cluster volume is 1,368 mm(3), p < 0.05 corrected for false discovery rate) in the pontomedullary junction of the brainstem in PD patients as compared to healthy controls. Furthermore, absolute grey matter volume was significantly higher in the brainstem of the PD group compared to healthy controls. We conclude that this cluster may reflect α-synuclein induced microstructural brainstem pathology in PD.

  1. Improved fiber-optic link for the phase reference distribution system for the TESLA technology based projects

    NASA Astrophysics Data System (ADS)

    Czuba, Krzysztof; Felber, Matthias

    2005-09-01

    The UV Free-Electron Laser (UVFEL) [1], The X-Ray Free-Electron Laser (XFEL) [2] and The International Linear Accelerator (ILC) [9] projects will require phase synchronization of various RF frequency subsystems on kilometer distances with accuracy better than 1ps. To fulfill these requirements, a phase reference distribution system concept was proposed and a prototype was developed for tests in the TESLA Test Facility 2 (TTF2). An important part of the phase reference system is the fiber-optic phase stable, long distance link described in this paper. An interferometrical scheme with feedback on phase, suppressing long term phase drifts induced by temperature changes was developed and tested in laboratory and under accelerator conditions. A motorized optical delay line was used in the system to compensate for phase errors. Described are error considerations and most important project issues like the hardware development and the real time phase controller software. The presented measurement results satisfy the design requirements. Experience gained during the experiments yielded proposals for system improvements.

  2. Multi-Shell Hybrid Diffusion Imaging (HYDI) at 7 Tesla in TgF344-AD Transgenic Alzheimer Rats

    PubMed Central

    Daianu, Madelaine; Jacobs, Russell E.; Weitz, Tara M.; Town, Terrence C.; Thompson, Paul M.

    2015-01-01

    Diffusion weighted imaging (DWI) is widely used to study microstructural characteristics of the brain. Diffusion tensor imaging (DTI) and high-angular resolution imaging (HARDI) are frequently used in radiology and neuroscience research but can be limited in describing the signal behavior in composite nerve fiber structures. Here, we developed and assessed the benefit of a comprehensive diffusion encoding scheme, known as hybrid diffusion imaging (HYDI), composed of 300 DWI volumes acquired at 7-Tesla with diffusion weightings at b = 1000, 3000, 4000, 8000 and 12000 s/mm2 and applied it in transgenic Alzheimer rats (line TgF344-AD) that model the full clinico-pathological spectrum of the human disease. We studied and visualized the effects of the multiple concentric “shells” when computing three distinct anisotropy maps–fractional anisotropy (FA), generalized fractional anisotropy (GFA) and normalized quantitative anisotropy (NQA). We tested the added value of the multi-shell q-space sampling scheme, when reconstructing neural pathways using mathematical frameworks from DTI and q-ball imaging (QBI). We show a range of properties of HYDI, including lower apparent anisotropy when using high b-value shells in DTI-based reconstructions, and increases in apparent anisotropy in QBI-based reconstructions. Regardless of the reconstruction scheme, HYDI improves FA-, GFA- and NQA-aided tractography. HYDI may be valuable in human connectome projects and clinical research, as well as magnetic resonance research in experimental animals. PMID:26683657

  3. Differences in Velopharyngeal Structure during Speech among Asians Revealed by 3-Tesla Magnetic Resonance Imaging Movie Mode

    PubMed Central

    Nunthayanon, Kulthida; Honda, Ei-ichi; Shimazaki, Kazuo; Ohmori, Hiroko; Inoue-Arai, Maristela Sayuri; Kurabayashi, Tohru; Ono, Takashi

    2015-01-01

    Objective. Different bony structures can affect the function of the velopharyngeal muscles. Asian populations differ morphologically, including the morphologies of their bony structures. The purpose of this study was to compare the velopharyngeal structures during speech in two Asian populations: Japanese and Thai. Methods. Ten healthy Japanese and Thai females (five each) were evaluated with a 3-Tesla (3 T) magnetic resonance imaging (MRI) scanner while they produced vowel-consonant-vowel syllable (/asa/). A gradient-echo sequence, fast low-angle shot with segmented cine and parallel imaging technique was used to obtain sagittal images of the velopharyngeal structures. Results. MRI was carried out in real time during speech production, allowing investigations of the time-to-time changes in the velopharyngeal structures. Thai subjects had a significantly longer hard palate and produced shorter consonant than Japanese subjects. The velum of the Thai participants showed significant thickening during consonant production and their retroglossal space was significantly wider at rest, whereas the dimensional change during task performance was similar in the two populations. Conclusions. The 3 T MRI movie method can be used to investigate velopharyngeal function and diagnose velopharyngeal insufficiency. The racial differences may include differences in skeletal patterns and soft-tissue morphology that result in functional differences for the affected structures. PMID:26273584

  4. High-temperature superconductor bulk magnets that can trap magnetic fields of over 17 tesla at 29 K.

    PubMed

    Tomita, Masaru; Murakami, Masato

    2003-01-30

    Large-grain high-temperature superconductors of the form RE-Ba-Cu-O (where RE is a rare-earth element) can trap magnetic fields of several tesla at low temperatures, and so can be used for permanent magnet applications. The magnitude of the trapped field is proportional to the critical current density and the volume of the superconductor. Various potential engineering applications for such magnets have emerged, and some have already been commercialized. However, the range of applications is limited by poor mechanical stability and low thermal conductivity of the bulk superconductors; RE-Ba-Cu-O magnets have been found to fracture during high-field activation, owing to magnetic pressure. Here we present a post-fabrication treatment that improves the mechanical properties as well as thermal conductivity of a bulk Y-Ba-Cu-O magnet, thereby increasing its field-trapping capacity. First, resin impregnation and wrapping the materials in carbon fibre improves the mechanical properties. Second, a small hole drilled into the centre of the magnet allows impregnation of Bi-Pb-Sn-Cd alloy into the superconductor and inclusion of an aluminium wire support, which results in a significant enhancement of thermal stability and internal mechanical strength. As a result, 17.24 T could be trapped, without fracturing, in a bulk Y-Ba-Cu-O sample of 2.65 cm diameter at 29 K.

  5. Spectroscopic correlates of antidepressant response to sleep deprivation and light therapy: a 3.0 Tesla study of bipolar depression.

    PubMed

    Benedetti, Francesco; Calabrese, Giovanna; Bernasconi, Alessandro; Cadioli, Marcello; Colombo, Cristina; Dallaspezia, Sara; Falini, Andrea; Radaelli, Daniele; Scotti, Giuseppe; Smeraldi, Enrico

    2009-09-30

    Glutamate is the primary excitatory neurotransmitter of the human brain, and recent findings suggest a role for the glutamatergic system in the pathophysiology and treatment of mood disorders. Single proton magnetic resonance spectroscopy (1H-MRS) was used to study the relative in vivo levels of brain neural metabolites. We evaluated the effect of antidepressant treatments on the relative concentration of unresolved glutamate and glutamine (Glx) with GABA contamination (2.35 ppm peak) using single voxel 1H-MRS at 3.0 Tesla. We studied 19 inpatients (7 males, 12 females) affected by bipolar disorder type I, current depressive episode without psychotic features, before and after 1 week of treatment with repeated total sleep deprivation (TSD) combined with light therapy (LT). Chronobiological treatment caused a significant amelioration in mood levels. Changes in the brain Glx/creatine ratio followed a general trend toward decrease, with individual variability. We observed that the decrease in the Glx/creatine ratio significantly correlated with the improvement of both objective and subjective measures of depression.

  6. Multi-voxel magnetic resonance spectroscopy of cerebral metabolites in healthy dogs at 1.5 Tesla

    PubMed Central

    Choi, Sooyoung; Song, Yumi; Lee, Kija; Lee, Youngwon

    2016-01-01

    This study was conducted to measure the difference in levels of cerebral metabolites in the right and left hemispheres, gray (GM) and white matter (WM), imaging planes, and anatomical regions of healthy dogs to establish normal variations. Eight male Beagle dogs (1 to 4 years of age; mean age, 2 years) with no evidence of neurologic disease were studied. Using the multi-voxel technique on a 1.5 Tesla magnetic resonance imaging scanner, metabolite values (N-acetyl aspartate [NAA], choline [Cho], creatine [Cr]) were obtained from the frontoparietal WM, parietal GM, temporal GM, occipital GM, thalamus, cerebellum, mid-brain, and pons. There was no significant difference in levels of these metabolites between the right and left in any locations or between the GM and WM in the cerebral hemispheres. However, there were significant differences in metabolite ratios within imaging planes. The NAA/Cr was lower in the cerebellum than other regions and the thalamus had a higher Cho/Cr and lower NAA/Cho ratio than in other regions. The spectral and metabolic values will provide a useful internal reference for clinical practice and research involving multi-voxel magnetic resonance spectroscopy. Measurement of metabolite values in the transverse plane is recommended for comparing levels of regional metabolites. PMID:26645339

  7. Characterization of transceive surface element designs for 7 tesla magnetic resonance imaging of the prostate: radiative antenna and microstrip.

    PubMed

    Ipek, O; Raaijmakers, A J E; Klomp, D W J; Lagendijk, J J W; Luijten, P R; van den Berg, C A T

    2012-01-21

    Ultra-high field magnetic resonance (≥7 tesla) imaging (MRI) faces challenges with respect to efficient spin excitation and signal reception from deeply situated organs. Traditional radio frequency surface coil designs relying on near-field coupling are suboptimal at high field strengths. Better signal penetration can be obtained by designing a radiative antenna in which the energy flux is directed to the target location. In this paper, two different radiative antenna designs are investigated to be used as transceive elements, which employ different dielectric permittivities for the antenna substrate. Their transmit and receive performances in terms of B(+)(1), local SAR (specific absorption rate) and SNR (signal-to-noise ratio) were compared using extensive electromagnetic simulations and MRI measurements with traditional surface microstrip coils. Both simulations and measurements demonstrated that the radiative element shows twofold gain in B(+)(1) and SNR at 10 cm depth, and additionally a comparable SAR peak value. In terms of transmit performance, the radiative antenna with a dielectric permittivity of 37 showed a 24% more favorable local SAR(10g avg)/(B(+)(1))(2) ratio than the radiative antenna with a dielectric permittivity of 90. In receive, the radiative element with a dielectric permittivity of 90 resulted in a 20% higher SNR for shallow depths, but for larger depths this difference diminished compared to the radiative element with a dielectric permittivity of 37. Therefore, to image deep anatomical regions effectively, the radiative antenna with a dielectric permittivity of 37 is favorable. PMID:22170777

  8. The cortical organization of audio-visual sentence comprehension: an fMRI study at 4 Tesla.

    PubMed

    Capek, Cheryl M; Bavelier, Daphne; Corina, David; Newman, Aaron J; Jezzard, Peter; Neville, Helen J

    2004-07-01

    Neuroimaging studies of written and spoken sentence processing report greater left hemisphere than right hemisphere activation. However, a large majority of our experience with language is face-to-face interaction, which is much richer in information. The current study examines the neural organization of audio-visual (AV) sentence processing using functional magnetic resonance imaging (fMRI) at 4 Tesla. Participants viewed the face and upper body of a speaker via a video screen while listening to her produce, in alternating blocks, English sentences and sentences composed of pronounceable non-words. Audio-visual sentence processing was associated with activation in the left hemisphere in Broca's area, dorsolateral prefrontal cortex, the superior precentral sulcus, anterior and middle portions of the lateral sulcus, middle superior portions of the temporal sulcus, supramarginal gyrus and angular gyrus. Further, AV sentence processing elicited activation in the right anterior and middle lateral sulcus. Between-hemisphere analyses revealed a left hemisphere dominant pattern of activation. The findings support the hypothesis that the left hemisphere may be biased to process language independently of the modality through which it is perceived. These results are discussed in the context of previous neuroimaging results using American Sign Language (ASL).

  9. Geometric accuracy of 3D coordinates of the Leksell stereotactic skull frame in 1.5 Tesla- and 3.0 Tesla-magnetic resonance imaging: a comparison of three different fixation screw materials.

    PubMed

    Nakazawa, Hisato; Mori, Yoshimasa; Yamamuro, Osamu; Komori, Masataka; Shibamoto, Yuta; Uchiyama, Yukio; Tsugawa, Takahiko; Hagiwara, Masahiro

    2014-11-01

    We assessed the geometric distortion of 1.5-Tesla (T) and 3.0-T magnetic resonance (MR) images with the Leksell skull frame system using three types of cranial quick fixation screws (QFSs) of different materials-aluminum, aluminum with tungsten tip, and titanium-for skull frame fixation. Two kinds of acrylic phantoms were placed on a Leksell skull frame using the three types of screws, and were scanned with computed tomography (CT), 1.5-T MR imaging and 3.0-T MR imaging. The 3D coordinates for both strengths of MR imaging were compared with those for CT. The deviations of the measured coordinates at selected points (x = 50, 100 and 150; y = 50, 100 and 150) were indicated on different axial planes (z = 50, 75, 100, 125 and 150). The errors of coordinates with QFSs of aluminum, tungsten-tipped aluminum, and titanium were <1.0, 1.0 and 2.0 mm in the entire treatable area, respectively, with 1.5 T. In the 3.0-T field, the errors with aluminum QFSs were <1.0 mm only around the center, while the errors with tungsten-tipped aluminum and titanium were >2.0 mm in most positions. The geometric accuracy of the Leksell skull frame system with 1.5-T MR imaging was high and valid for clinical use. However, the geometric errors with 3.0-T MR imaging were larger than those of 1.5-T MR imaging and were acceptable only with aluminum QFSs, and then only around the central region.

  10. Texture-based and diffusion-weighted discrimination of parotid gland lesions on MR images at 3.0 Tesla.

    PubMed

    Fruehwald-Pallamar, Julia; Czerny, Christian; Holzer-Fruehwald, Laura; Nemec, Stefan F; Mueller-Mang, Christina; Weber, Michael; Mayerhoefer, Marius E

    2013-11-01

    The purpose of this study was to evaluate whether texture-based analysis of standard MRI sequences and diffusion-weighted imaging can help in the discrimination of parotid gland masses. The MR images of 38 patients with a biopsy- or surgery-proven parotid gland mass were retrospectively analyzed. All patients were examined on the same 3.0 Tesla MR unit, with one standard protocol. The ADC (apparent diffusion coefficient) values of the tumors were measured with three regions of interest (ROIs) covering the entire tumor. Texture-based analysis was performed with the texture analysis software MaZda (version 4.7), with ROI measurements covering the entire tumor in three slices. COC (co-occurrence matrix), RUN (run-length matrix), GRA (gradient), ARM (auto-regressive model), and WAV (wavelet transform) features were calculated for all ROIs. Three subsets of 10 texture features each were used for a linear discriminant analysis (LDA) in combination with k nearest neighbor classification (k-NN). Using histology as a standard of reference, benign tumors, including subtypes, and malignant tumors were compared with regard to ADC and texture-based values, with a one-way analysis of variance with post-hoc t-tests. Significant differences were found in the mean ADC values between Warthin tumors and pleomorphic adenomas, as well as between Warthin tumors and benign lesions. Contrast-enhanced T1-weighted images contained the most relevant textural information for the discrimination between benign and malignant parotid masses, and also for the discrimination between pleomorphic adenomas and Warthin tumors. STIR images contained the least relevant texture features, particularly for the discrimination between pleomorphic adenomas and Warthin tumors. Texture analysis proved to differentiate benign from malignant lesions, as well as pleomorphic adenomas from Warthin tumors, based on standard T(1w) sequences (without and with contrast). Of all benign parotid masses, Warthin tumors had

  11. The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study.

    PubMed

    Schallmo, Michael-Paul; Grant, Andrea N; Burton, Philip C; Olman, Cheryl A

    2016-08-01

    Although V1 responses are driven primarily by elements within a neuron's receptive field, which subtends about 1° visual angle in parafoveal regions, previous work has shown that localized fMRI responses to visual elements reflect not only local feature encoding but also long-range pattern attributes. However, separating the response to an image feature from the response to the surrounding stimulus and studying the interactions between these two responses demands both spatial precision and signal independence, which may be challenging to attain with fMRI. The present study used 7 Tesla fMRI with 1.2-mm resolution to measure the interactions between small sinusoidal grating patches (targets) at 3° eccentricity and surrounds of various sizes and orientations to test the conditions under which localized, context-dependent fMRI responses could be predicted from either psychophysical or electrophysiological data. Targets were presented at 8%, 16%, and 32% contrast while manipulating (a) spatial extent of parallel (strongly suppressive) or orthogonal (weakly suppressive) surrounds, (b) locus of attention, (c) stimulus onset asynchrony between target and surround, and (d) blocked versus event-related design. In all experiments, the V1 fMRI signal was lower when target stimuli were flanked by parallel versus orthogonal context. Attention amplified fMRI responses to all stimuli but did not show a selective effect on central target responses or a measurable effect on orientation-dependent surround suppression. Suppression of the V1 fMRI response by parallel surrounds was stronger than predicted from psychophysics but showed a better match to previous electrophysiological reports.

  12. Single session imaging of cerebellum at 7 Tesla: obtaining structure and function of multiple motor subsystems in individual subjects.

    PubMed

    Batson, Melissa A; Petridou, Natalia; Klomp, Dennis W J; Frens, Maarten A; Neggers, Sebastiaan F W

    2015-01-01

    The recent increase in the use of high field MR systems is accompanied by a demand for acquisition techniques and coil systems that can take advantage of increased power and accuracy without being susceptible to increased noise. Physical location and anatomical complexity of targeted regions must be considered when attempting to image deeper structures with small nuclei and/or complex cytoarchitechtonics (i.e. small microvasculature and deep nuclei), such as the brainstem and the cerebellum (Cb). Once these obstacles are overcome, the concomitant increase in signal strength at higher field strength should allow for faster acquisition of MR images. Here we show that it is technically feasible to quickly and accurately detect blood oxygen level dependent (BOLD) signal changes and obtain anatomical images of Cb at high spatial resolutions in individual subjects at 7 Tesla in a single one-hour session. Images were obtained using two high-density multi-element surface coils (32 channels in total) placed beneath the head at the level of Cb, two channel transmission, and three-dimensional sensitivity encoded (3D, SENSE) acquisitions to investigate sensorimotor activations in Cb. Two classic sensorimotor tasks were used to detect Cb activations. BOLD signal changes during motor activity resulted in concentrated clusters of activity within the Cb lobules associated with each task, observed consistently and independently in each subject: Oculomotor vermis (VI/VII) and CrusI/II for pro- and anti-saccades; ipsilateral hemispheres IV-VI for finger tapping; and topographical separation of eye- and hand- activations in hemispheres VI and VIIb/VIII. Though fast temporal resolution was not attempted here, these functional patches of highly specific BOLD signal changes may reflect small-scale shunting of blood in the microvasculature of Cb. The observed improvements in acquisition time and signal detection are ideal for individualized investigations such as differentiation of

  13. Single session imaging of cerebellum at 7 Tesla: obtaining structure and function of multiple motor subsystems in individual subjects.

    PubMed

    Batson, Melissa A; Petridou, Natalia; Klomp, Dennis W J; Frens, Maarten A; Neggers, Sebastiaan F W

    2015-01-01

    The recent increase in the use of high field MR systems is accompanied by a demand for acquisition techniques and coil systems that can take advantage of increased power and accuracy without being susceptible to increased noise. Physical location and anatomical complexity of targeted regions must be considered when attempting to image deeper structures with small nuclei and/or complex cytoarchitechtonics (i.e. small microvasculature and deep nuclei), such as the brainstem and the cerebellum (Cb). Once these obstacles are overcome, the concomitant increase in signal strength at higher field strength should allow for faster acquisition of MR images. Here we show that it is technically feasible to quickly and accurately detect blood oxygen level dependent (BOLD) signal changes and obtain anatomical images of Cb at high spatial resolutions in individual subjects at 7 Tesla in a single one-hour session. Images were obtained using two high-density multi-element surface coils (32 channels in total) placed beneath the head at the level of Cb, two channel transmission, and three-dimensional sensitivity encoded (3D, SENSE) acquisitions to investigate sensorimotor activations in Cb. Two classic sensorimotor tasks were used to detect Cb activations. BOLD signal changes during motor activity resulted in concentrated clusters of activity within the Cb lobules associated with each task, observed consistently and independently in each subject: Oculomotor vermis (VI/VII) and CrusI/II for pro- and anti-saccades; ipsilateral hemispheres IV-VI for finger tapping; and topographical separation of eye- and hand- activations in hemispheres VI and VIIb/VIII. Though fast temporal resolution was not attempted here, these functional patches of highly specific BOLD signal changes may reflect small-scale shunting of blood in the microvasculature of Cb. The observed improvements in acquisition time and signal detection are ideal for individualized investigations such as differentiation of

  14. Multimodal image registration of ex vivo 4 Tesla MRI with whole mount histology for prostate cancer detection

    NASA Astrophysics Data System (ADS)

    Chappelow, Jonathan; Madabhushi, Anant; Rosen, Mark; Tomaszeweski, John; Feldman, Michael

    2007-03-01

    In this paper we present novel methods for registration and subsequent evaluation of whole mount prostate histological sections to corresponding 4 Tesla ex vivo magnetic resonance imaging (MRI) slices to complement our existing computer-aided diagnosis (CAD) system for detection of prostatic adenocarcinoma from high resolution MRI. The CAD system is trained using voxels labeled as cancer on MRI by experts who visually aligned histology with MRI. To address voxel labeling errors on account of manual alignment and delineation, we have developed a registration method called combined feature ensemble mutual information (COFEMI) to automatically map spatial extent of prostate cancer from histology onto corresponding MRI for prostatectomy specimens. Our method improves over intensity-based similarity metrics (mutual information) by incorporating unique information from feature spaces that are relatively robust to intensity artifacts and which accentuate the structural details in the target and template images to be registered. Our registration algorithm accounts for linear gland deformations in the histological sections resulting from gland fixing and serial sectioning. Following automatic registration of MRI and histology, cancer extent from histological sections are mapped to the corresponding registered MRI slices. The manually delineated cancer areas on MRI obtained via manual alignment of histological sections and MRI are compared with corresponding cancer extent obtained via COFEMI by a novel registration evaluation technique based on use of non-linear dimensionality reduction (locally linear embedding (LLE)). The cancer map on MRI determined by COFEMI was found to be significantly more accurate compared to the manually determined cancer mask. The performance of COFEMI was also found to be superior compared to image intensity-based mutual information registration.

  15. The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study.

    PubMed

    Schallmo, Michael-Paul; Grant, Andrea N; Burton, Philip C; Olman, Cheryl A

    2016-08-01

    Although V1 responses are driven primarily by elements within a neuron's receptive field, which subtends about 1° visual angle in parafoveal regions, previous work has shown that localized fMRI responses to visual elements reflect not only local feature encoding but also long-range pattern attributes. However, separating the response to an image feature from the response to the surrounding stimulus and studying the interactions between these two responses demands both spatial precision and signal independence, which may be challenging to attain with fMRI. The present study used 7 Tesla fMRI with 1.2-mm resolution to measure the interactions between small sinusoidal grating patches (targets) at 3° eccentricity and surrounds of various sizes and orientations to test the conditions under which localized, context-dependent fMRI responses could be predicted from either psychophysical or electrophysiological data. Targets were presented at 8%, 16%, and 32% contrast while manipulating (a) spatial extent of parallel (strongly suppressive) or orthogonal (weakly suppressive) surrounds, (b) locus of attention, (c) stimulus onset asynchrony between target and surround, and (d) blocked versus event-related design. In all experiments, the V1 fMRI signal was lower when target stimuli were flanked by parallel versus orthogonal context. Attention amplified fMRI responses to all stimuli but did not show a selective effect on central target responses or a measurable effect on orientation-dependent surround suppression. Suppression of the V1 fMRI response by parallel surrounds was stronger than predicted from psychophysics but showed a better match to previous electrophysiological reports. PMID:27565016

  16. The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study

    PubMed Central

    Schallmo, Michael-Paul; Grant, Andrea N.; Burton, Philip C.; Olman, Cheryl A.

    2016-01-01

    Although V1 responses are driven primarily by elements within a neuron's receptive field, which subtends about 1° visual angle in parafoveal regions, previous work has shown that localized fMRI responses to visual elements reflect not only local feature encoding but also long-range pattern attributes. However, separating the response to an image feature from the response to the surrounding stimulus and studying the interactions between these two responses demands both spatial precision and signal independence, which may be challenging to attain with fMRI. The present study used 7 Tesla fMRI with 1.2-mm resolution to measure the interactions between small sinusoidal grating patches (targets) at 3° eccentricity and surrounds of various sizes and orientations to test the conditions under which localized, context-dependent fMRI responses could be predicted from either psychophysical or electrophysiological data. Targets were presented at 8%, 16%, and 32% contrast while manipulating (a) spatial extent of parallel (strongly suppressive) or orthogonal (weakly suppressive) surrounds, (b) locus of attention, (c) stimulus onset asynchrony between target and surround, and (d) blocked versus event-related design. In all experiments, the V1 fMRI signal was lower when target stimuli were flanked by parallel versus orthogonal context. Attention amplified fMRI responses to all stimuli but did not show a selective effect on central target responses or a measurable effect on orientation-dependent surround suppression. Suppression of the V1 fMRI response by parallel surrounds was stronger than predicted from psychophysics but showed a better match to previous electrophysiological reports. PMID:27565016

  17. High resolution (3 Tesla) MRI-guided conformal brachytherapy for cervical cancer: consequences of different high-risk CTV sizes

    PubMed Central

    Anderson, James W.; Xia, Junyi; Flynn, Ryan T.; Modrick, Joseph M.; Bhatia, Sudershan K.; Jacobson, Geraldine M.

    2013-01-01

    Purpose To evaluate conventional brachytherapy (BT) plans using dose-volume parameters and high resolution (3 Tesla) MRI datasets, and to quantify dosimetric benefits and limitations when MRI-guided, conformal BT (MRIG-CBT) plans are generated. Material and methods Fifty-five clinical high-dose-rate BT plans from 14 cervical cancer patients were retrospectively studied. All conventional plans were created using MRI with titanium tandem-and-ovoid applicator (T&O) for delivery. For each conventional plan, a MRIG-CBT plan was retrospectively generated using hybrid inverse optimization. Three categories of high risk (HR)-CTV were considered based on volume: non-bulky (< 20 cc), low-bulky (> 20 cc and < 40 cc) and bulky (≥ 40 cc). Dose-volume metrics of D90 of HR-CTV and D2cc and D0.1cc of rectum, bladder, and sigmoid colon were analyzed. Results Tumor coverage (HR-CTV D90) of the conventional plans was considerably affected by the HR-CTV size. Sixteen percent of the plans covered HR-CTV D90 with the prescription dose within 5%. At least one OAR had D2cc values over the GEC-ESTRO recommended limits in 52.7% of the conventional plans. MRIG-CBT plans showed improved target coverage for HR-CTV D90 of 98 and 97% of the prescribed dose for non-bulky and low-bulky tumors, respectively. No MRIG-CBT plans surpassed the D2cc limits of any OAR. Only small improvements (D90 of 80%) were found for large targets (> 40 cc) when using T&O applicator approach. Conclusions MRIG-CBT plans displayed considerable improvement for tumor coverage and OAR sparing over conventional treatment. When the HR-CTV volume exceeded 40 cc, its improvements were diminished when using a conventional intracavitary applicator. PMID:23878555

  18. Endometrium evaluation with high-field (3-Tesla) magnetic resonance imaging in patients submitted to uterine leiomyoma embolization

    PubMed Central

    Jacobs, Monica Amadio Piazza; Nasser, Felipe; Zlotnik, Eduardo; Messina, Marcos de Lorenzo; Baroni, Ronaldo Hueb

    2013-01-01

    ABSTRACT Objective: To evaluate the endometrial alterations related to embolization of uterine arteries for the treatment of symptomatic uterine leiomyomatosis (pelvic pain and/or uterine bleeding) by means of high-field (3-Tesla) magnetic resonance. Methods: This is a longitudinal and prospective study that included 94 patients with a clinical and imaging diagnosis of symptomatic uterine leiomyomatosis, all of them treated by embolization of the uterine arteries. The patients were submitted to evaluations by high-field magnetic resonance of the pelvis before and 6 months after the procedure. Specific evaluations were made of the endometrium on the T2-weighted sequences, and on the T1-weighted sequences before and after the intravenous dynamic infusion of the paramagnetic contrast. In face of these measures, statistical analyses were performed using Student's t test for comparison of the results obtained before and after the procedure. Results: An average increase of 20.9% was noted in the endometrial signal on T2-weighted images obtained after the uterine artery embolization procedure when compared to the pre-procedure evaluation (p=0.0004). In the images obtained with the intravenous infusion of paramagnetic contrast, an average increase of 18.7% was noted in the post-embolization intensity of the endometrial signal, compared to the pre-embolization measure (p<0.035). Conclusion: After embolization of the uterine arteries, there was a significant increase of the endometrial signal on the T2-weighted images and on the post-contrast images, inferring possible edema and increased endometrial flow. Future studies are needed to assess the clinical impact of these findings. PMID:23579745

  19. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    PubMed Central

    Winter, Lukas; Dieringer, Matthias A.; Els, Antje; Oezerdem, Celal; Rieger, Jan; Kuehne, Andre; Cassara, Antonino M.; Pfeiffer, Harald; Wetterling, Friedrich; Niendorf, Thoralf

    2016-01-01

    Introduction The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation. Methods Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated. Results Our simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit. Conclusion Pursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants. PMID:27598923

  20. Improved Cerebral Time-of-Flight Magnetic Resonance Angiography at 7 Tesla – Feasibility Study and Preliminary Results Using Optimized Venous Saturation Pulses

    PubMed Central

    Wrede, Karsten H.; Johst, Sören; Dammann, Philipp; Özkan, Neriman; Mönninghoff, Christoph; Kraemer, Markus; Maderwald, Stefan; Ladd, Mark E.; Sure, Ulrich; Umutlu, Lale; Schlamann, Marc

    2014-01-01

    Purpose Conventional saturation pulses cannot be used for 7 Tesla ultra-high-resolution time-of-flight magnetic resonance angiography (TOF MRA) due to specific absorption rate (SAR) limitations. We overcome these limitations by utilizing low flip angle, variable rate selective excitation (VERSE) algorithm saturation pulses. Material and Methods Twenty-five neurosurgical patients (male n = 8, female n = 17; average age 49.64 years; range 26–70 years) with different intracranial vascular pathologies were enrolled in this trial. All patients were examined with a 7 Tesla (Magnetom 7 T, Siemens) whole body scanner system utilizing a dedicated 32-channel head coil. For venous saturation pulses a 35° flip angle was applied. Two neuroradiologists evaluated the delineation of arterial vessels in the Circle of Willis, delineation of vascular pathologies, presence of artifacts, vessel-tissue contrast and overall image quality of TOF MRA scans in consensus on a five-point scale. Normalized signal intensities in the confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter were measured and vessel-tissue contrasts were calculated. Results Ratings for the majority of patients ranged between good and excellent for most of the evaluated features. Venous saturation was sufficient for all cases with minor artifacts in arteriovenous malformations and arteriovenous fistulas. Quantitative signal intensity measurements showed high vessel-tissue contrast for confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter. Conclusion The use of novel low flip angle VERSE algorithm pulses for saturation of venous vessels can overcome SAR limitations in 7 Tesla ultra-high-resolution TOF MRA. Our protocol is suitable for clinical application with excellent image quality for delineation of various intracranial vascular pathologies. PMID:25232868

  1. Nonenhanced peripheral MR-angiography (MRA) at 3 Tesla: evaluation of quiescent-interval single-shot MRA in patients undergoing digital subtraction angiography.

    PubMed

    Wagner, Moritz; Knobloch, Gesine; Gielen, Martin; Lauff, Marie-Teres; Romano, Valentina; Hamm, Bernd; Kröncke, Thomas

    2015-04-01

    Quiescent-interval single-shot MRA (QISS-MRA) is a promising nonenhanced imaging technique for assessment of peripheral arterial disease (PAD). Previous studies at 3 Tesla included only very limited numbers of patients for correlation of QISS-MRA with digital subtraction angiography (DSA) as standard of reference (SOR). The aim of this prospective institutional review board-approved study was to compare QISS-MRA at 3 Tesla with DSA in a larger patient group. Our study included 32 consecutive patients who underwent QISS-MRA, contrast-enhanced MRA (CE-MRA), and DSA. Two readers independently performed a per-segment evaluation of QISS-MRA and CE-MRA for image quality and identification of non-significant stenosis (<50%) versus significant stenosis (50-100%). The final dataset included 1,027 vessel segments. Reader 1 and 2 rated image quality as diagnostic in 96.8 and 98.0% of the vessel segments on QISS-MRA and in 99.3 and 98.4% of the vessel segments on CE-MRA, respectively. DSA was available for 922 segments and detected significant stenosis in 133 segments (14.4%). Consensus reading yielded the following diagnostic parameters for QISS-MRA versus CE-MRA: sensitivity: 83.5% (111/133) versus 82.7% (110/133), p = 0.80; specificity: 93.9% (741/789) versus 95.7% (755/789), p = 0.25; and diagnostic accuracy: 92.4% (852/922) versus 93.8% (865/922), p = 0.35. In conclusion, using DSA as SOR, QISS-MRA and CE-MRA at 3 Tesla showed similar diagnostic accuracy in the assessment of PAD. A limitation of QISS-MRA was the lower rate of assessable vessel segments compared to CE-MRA.

  2. In vivo High Angular Resolution Diffusion-Weighted Imaging of Mouse Brain at 16.4 Tesla

    PubMed Central

    Alomair, Othman I.; Brereton, Ian M.; Smith, Maree T.; Galloway, Graham J.; Kurniawan, Nyoman D.

    2015-01-01

    Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM

  3. In vivo high angular resolution diffusion-weighted imaging of mouse brain at 16.4 Tesla.

    PubMed

    Alomair, Othman I; Brereton, Ian M; Smith, Maree T; Galloway, Graham J; Kurniawan, Nyoman D

    2015-01-01

    Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM

  4. A Two-dimensional Sixteen Channel Transmit/Receive Coil Array for Cardiac MRI at 7.0 Tesla: Design, Evaluation and Application

    PubMed Central

    Thalhammer, Christof; Renz, Wolfgang; Winter, Lukas; Hezel, Fabian; Rieger, Jan; Pfeiffer, Harald; Graessl, Andreas; Seifert, Frank; Hoffmann, Werner; von Knobelsdorff-Brenkenhoff, Florian; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Kellman, Peter; Niendorf, Thoralf

    2012-01-01

    Purpose To design, evaluate and apply a two-dimensional 16 channel transmit/receive coil array tailored for cardiac MRI at 7.0 Tesla. Material and Methods The cardiac coil array consists of 2 sections each using 8 elements arranged in a 2 × 4 array. RF safety was validated by SAR simulations. Cardiac imaging was performed using 2D CINE FLASH imaging, T2* mapping and fat-water separation imaging. The characteristics of the coil array were analyzed including parallel imaging performance, left ventricular chamber quantification and overall image quality. Results RF characteristics were found to be appropriate for all subjects included in the study. The SAR values derived from the simulations fall well in the limits of legal guidelines. The baseline SNR advantage at 7.0 T was put to use to acquire 2D CINE images of the heart with a very high spatial resolution of (1 × 1 × 4) mm3. The proposed coil array supports 1D acceleration factors of up to R=4 without impairing image quality significantly. Conclusions The 16 channel TX/RX coil has the capability to acquire high contrast and high spatial resolution images of the heart at 7.0 Tesla. PMID:22706727

  5. Measurement of the weighted peak level for occupational exposure to gradient magnetic fields for 1.5 and 3 Tesla MRI body scanners.

    PubMed

    Bonutti, F; Tecchio, M; Maieron, M; Trevisan, D; Negro, C; Calligaris, F

    2016-03-01

    The purpose of this work is to give a contribution to the construction of a comprehensive knowledge of the exposure levels to gradient magnetic fields (GMF) in terms of the weighed peak (WP), especially for 3 Tesla scanners for which there are still few works available in the literature. A new generation probe for the measurement of electromagnetic fields in the range of 1 Hz-400 kHz was used to assess the occupational exposure levels to the GMF for 1.5 and 3.0 Tesla MRI body scanners, using the method of the WP according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) approach. The probe was placed at a height of 1.1 m, close to the MRI scanners, where operators could stay during some medical procedures with particular issues. The measurements were performed for a set of typical acquisition sequences for body (liver) and head exams. The measured values of WP were in compliance with ICNIRP 2010 reference levels for occupational exposures.

  6. Free-electron laser at the TESLA Test Facility at DESY: toward a tunable short-pulsed soft x-ray source

    NASA Astrophysics Data System (ADS)

    Gerth, Christopher

    2001-12-01

    A high peak current, low emittance, short pulse electron beam can produce intense, laser-like radiation in a single pass through a long periodic magnetic structure. The construction of such free-electron lasers (FELs) based on self-amplified spontaneous emission (SASE) has become feasible by recent advances in accelerator technologies. Since SASE FELs do not require any optical components they are promising sources for the generation of intense, sub- picosecond laser pulses which are continuously tunable over a wide wavelength range in the vacuum ultraviolet (VUV) and X-ray region. In the first phase of the VUV-FEL (phase I) at the TESLA Test Facility at DESY, SASE was achieved for the first time in the VUV at wavelengths between 80 and 180 nm. The concept of the VUV FEL at DESY and first experimental results are presented. The second phase of the TESLA Test Facility (phase II), which includes an increase of the electron beam energy to 1 GeV, aims at the construction of a SASE FEL operating in the soft X-ray region. An overview of the current status and the activities toward a soft X-ray FEL user facility is given.

  7. Lighten Up: Tesla.

    ERIC Educational Resources Information Center

    Wiebe, Ann

    1994-01-01

    Presents a lesson plan detailing an interdisciplinary mathematics/science activity in which students take a home survey of light bulbs and then design an energy-saving lighting system for a home. Contains reproducible student worksheets. (MKR)

  8. Evaluation of Artifacts and Distortions of Titanium Applicators on 3.0-Tesla MRI: Feasibility of Titanium Applicators in MRI-Guided Brachytherapy for Gynecological Cancer

    SciTech Connect

    Kim, Yusung; Muruganandham, Manickam; Modrick, Joseph M.; Bayouth, John E.

    2011-07-01

    Purpose: The aim of this study was to characterize the levels of artifacts and distortions of titanium applicators on 3.0-Tesla magnetic resonance imaging (MRI). Methods and Materials: Fletcher-Suit-Delclos-style tandem and ovoids (T and O) and tandem and ring applicator (T and R) were examined. The quality assurance (QA) phantoms for each applicator were designed and filled with copper sulphate solution (1.5 g/l). The artifacts were quantified with the registration of corresponding computed tomography (CT) images. A favorable MR sequence was searched in terms of artifacts. Using the sequence, the artifacts were determined. The geometric distortions induced by the applicators were quantified through each registration of CT and MRI without applicators. The artifacts of T and O were also evaluated on in vivo MRI datasets of 5 patients. Results: T1-weighted MRI with 1-mm slice thickness was found as a favorable MR sequence. Applying the sequence, the artifacts at the tandem tip of T and O and T and R were determined as 1.5 {+-} 0.5 mm in a superior direction in phantom studies. In the ovoids of T and O, we found artifacts less than 1.5 {+-} 0.5 mm. The artifacts of a T and O tandem in vivo were found as less than 2.6 {+-} 1.3 mm on T1-weighted MRI, whereas less than 6.9 {+-} 3.4 mm on T2-weighted MRI. No more than 1.2 {+-} 0.6 mm (3.0 {+-} 1.5 mm) of distortions, due to a titanium applicator, were measured on T1-weighted MRI (T2-). Conclusion: In 3.0-Tesla MRI, we found the artifact widths at the tip of tandem were less than 1.5 {+-} 0.5 mm for both T and O and T and R when using T1-weighted MRI in phantom studies. However, exclusive 3.0-Tesla MRI-guided brachytherapy planning with a titanium applicator should be cautiously implemented.

  9. Direct measurement of kilo-tesla level magnetic field generated with laser-driven capacitor-coil target by proton deflectometry

    NASA Astrophysics Data System (ADS)

    Law, K. F. F.; Bailly-Grandvaux, M.; Morace, A.; Sakata, S.; Matsuo, K.; Kojima, S.; Lee, S.; Vaisseau, X.; Arikawa, Y.; Yogo, A.; Kondo, K.; Zhang, Z.; Bellei, C.; Santos, J. J.; Fujioka, S.; Azechi, H.

    2016-02-01

    A kilo-tesla level, quasi-static magnetic field (B-field), which is generated with an intense laser-driven capacitor-coil target, was measured by proton deflectometry with a proper plasma shielding. Proton deflectometry is a direct and reliable method to diagnose strong, mm3-scale laser-produced B-field; however, this was not successful in the previous experiment. A target-normal-sheath-accelerated proton beam is deflected by Lorentz force in the laser-produced magnetic field with the resulting deflection pattern recorded on a radiochromic film stack. A 610 ± 30 T of B-field amplitude was inferred by comparing the experimental proton pattern with Monte-Carlo calculations. The amplitude and temporal evolutions of the laser-generated B-field were also measured by a differential magnetic probe, independently confirming the proton deflectometry measurement results.

  10. Cold RF test and associated mechanical features correlation of a TESLA-style 9-cell superconducting niobium cavity built in China

    SciTech Connect

    Dai, Jing; Quan, Sheng-Wen; Zhang, Bao-Cheng; Lin, Lin; Hao, Jian-Kui; Zhu, Feng; Xu, Wen-Can; He, Fei-Si; Jin, Song; Wang, Fang; Liu, Ke-Xin; Geng, R L; Zhao, Kui

    2012-02-01

    The RF performance of a 1.3 GHz 9-cell superconducting niobium cavity was evaluated at cryogenic temperatures following surface processing by using the standard ILC-style recipe. The cavity is a TESLA-style 9-cell superconducting niobium cavity, with complete end group components including a higher order mode coupler, built in China for practical applications. An accelerating gradient of 28.6 MV/m was achieved at an unloaded quality factor of 4 x 10{sup 9}. The morphological property of mechanical features on the RF surface of this cavity was characterized through optical inspection. Correlation between the observed mechanical features and the RF performance of the cavity is attempted.

  11. Design parameters for a 7.2 tesla bending magnet for a 1.5 GeV compact light source

    SciTech Connect

    Green, M.A.; Madura, D.

    1995-06-01

    This report describes the design for a 7.2 tesla superconducting dipole magnet for a compact synchrotron light source. The proposed magnet is a Vobly type modified picture frame dipole that has the flux returned through unsaturated iron. In this magnet, The iron in the pole pieces is highly saturated, Separately powered coils around the pole pieces are used to direct the flux lines until the flux can be returned through the unsaturated iron. The proposed dipole will develop a uniform field over a region that is 80 mm high by 130 mm wide over a range of central induction from 0.4 T to almost 8 T. Each dipole for the compact light source will have a magnetic length of about 0.38 meters.

  12. Design parameters for a 7.2 tesla bending magnet for a 1.5 GeV compact light source

    SciTech Connect

    Green, M.A.; Madura, D.

    1996-07-01

    This report describes the design for a 7.2 tesla superconducting dipole magnet for a compact synchrotron light source. The proposed magnet is a Vobly type modified picture frame dipole that has the flux returned through unsaturated iron. In this magnet, the iron in the pole pieces is highly saturated. Separately powered coils around the pole pieces are used to direct the flux lines until the flux can be returned through the unsaturated iron. The proposed dipole will develop a uniform field over a region that is 80 mm high by 130 mm wide over a range of central induction from 0.4 T to almost 8 T. Each dipole for the compact light source will have a magnetic length of about 0.38 meters.

  13. Modular version of SIMCON, FPGA based, DSP integrated, LLRF control system for TESLA FEL part I: SIMCON 3.0 motherboard

    NASA Astrophysics Data System (ADS)

    Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Kierzkowski, Krzysztof

    2006-03-01

    The paper includes a description of predicted functionalities to be implemented in a universal motherboard (MB) for the next generation of LLRF control system for TESLA. The motherboard bases on a number of quasi-autonomous embedded executive modules. The modules are implemented in a few FPGA chips featured by the MB. The paper presents a practical design of the MB. The initial (basic) solution of the MB has the Cyclone as the chip where the board management is embedded. The board features communication modules - VME and micro, single chip PC with Ethernet. The board provides power supply for the FPGA chips. The board has fast internal communication between particular modules. The described Motherboard serves for experiments with the SIMCON 3.0 system.

  14. A functional magnetic resonance imaging study of listening comprehension of languages in human at 3 tesla-comprehension level and activation of the language areas.

    PubMed

    Nakai, T; Matsuo, K; Kato, C; Matsuzawa, M; Okada, T; Glover, G H; Moriya, T; Inui, T

    1999-03-19

    Passive listening comprehension of native and non-native language was investigated using high resolution functional magnetic resonance imaging (fMRI) at a static magnetic field strength of 3 tesla. Wernicke's area was activated by comprehensive and non-comprehensive languages indicating that this area is associated with common phonological processing of language. The task with comprehensive but non-native language activated Broca's area and angular gyrus most frequently. The activations in these areas may be related to demand in semantic and syntactic processing in listening comprehension. Supplementary motor area and pre-motor area were activated by comprehensive languages but not by non-comprehensive language. These motor controlling areas may be involved in semantic processing. Listening to comprehensive but non-native language seems to demand more networked co-processing.

  15. Gray Matter-Specific Changes in Brain Bioenergetics after Acute Sleep Deprivation: A 31P Magnetic Resonance Spectroscopy Study at 4 Tesla

    PubMed Central

    Plante, David T.; Trksak, George H.; Jensen, J. Eric; Penetar, David M.; Ravichandran, Caitlin; Riedner, Brady A.; Tartarini, Wendy L.; Dorsey, Cynthia M.; Renshaw, Perry F.; Lukas, Scott E.; Harper, David G.

    2014-01-01

    Study Objectives: A principal function of sleep may be restoration of brain energy metabolism caused by the energetic demands of wakefulness. Because energetic demands in the brain are greater in gray than white matter, this study used linear mixed-effects models to examine tissue-type specific changes in high-energy phosphates derived using 31P magnetic resonance spectroscopy (MRS) after sleep deprivation and recovery sleep. Design: Experimental laboratory study. Setting: Outpatient neuroimaging center at a private psychiatric hospital. Participants: A total of 32 MRS scans performed in eight healthy individuals (mean age 35 y; range 23-51 y). Interventions: Phosphocreatine (PCr) and β-nucleoside triphosphate (NTP) were measured using 31P MRS three dimensional-chemical shift imaging at high field (4 Tesla) after a baseline night of sleep, acute sleep deprivation, and 2 nights of recovery sleep. Novel linear mixed-effects models were constructed using spectral and tissue segmentation data to examine changes in bioenergetics in gray and white matter. Measurements and Results: PCr increased in gray matter after 2 nights of recovery sleep relative to sleep deprivation with no significant changes in white matter. Exploratory analyses also demonstrated that increases in PCr were associated with increases in electroencephalographic slow wave activity during recovery sleep. No significant changes in β-NTP were observed. Conclusions: These results demonstrate that sleep deprivation and subsequent recovery-induced changes in high-energy phosphates primarily occur in gray matter, and increases in phosphocreatine after recovery sleep may be related to sleep homeostasis. Citation: Plante DT, Trksak GH, Jensen JE, Penetar DM, Ravichandran C, Riedner BA, Tartarini WL, Dorsey CM, Renshaw PF, Lukas SE, Harper DG. Gray matter-specific changes in brain bioenergetics after acute sleep deprivation: a 31P magnetic resonance spectroscopy study at 4 Tesla. SLEEP 2014

  16. Neurobehavioral effects among subjects exposed to high static and gradient magnetic fields from a 1.5 Tesla magnetic resonance imaging system--a case-crossover pilot study.

    PubMed

    de Vocht, Frank; van-Wendel-de-Joode, Berna; Engels, Hans; Kromhout, Hans

    2003-10-01

    The interactive use of magnetic resonance imaging (MRI) techniques is increasing in operating theaters. A study was performed on 17 male company volunteers to assess the neurobehavioral effects of exposure to magnetic fields from a 1.5 Tesla MRI system. The subjects' neurobehavioral performances on a neurobehavioral test battery were compared in four 1-hr sessions with and without exposure to magnetic fields, and with and without additional movements. Adverse effects were found for hand coordination (-4%, P < 0.05; Pursuit Aiming II) and near visual contrast sensitivity (-16% and -15%, P < 0.10; Vistech 6000). The results from the remaining tests were inconclusive due to a strong learning effect. No additional effect from gradient fields was detected. The results indicate that working near a 1.5 Tesla MRI system may lead to neurobehavioral effects. Further research is recommended, especially in members of operating teams using interactive MRI systems.

  17. Energetic and Cell Membrane Metabolic Products in Patients with Primary Insomnia: A 31-Phosphorus Magnetic Resonance Spectroscopy Study at 4 Tesla

    PubMed Central

    Harper, David G.; Plante, David T.; Jensen, J. Eric; Ravichandran, Caitlin; Buxton, Orfeu M.; Benson, Kathleen L.; O'Connor, Shawn P.; Renshaw, Perry F.; Winkelman, John W.

    2013-01-01

    Study Objectives: Primary insomnia (PI) is a sleep disorder characterized by difficulty with sleep initiation, maintenance, and/or the experience of nonrestorative sleep combined with a subsequent impairment of daytime functioning. The hyperarousal hypothesis has emerged as the leading candidate to explain insomnia symptoms in the absence of specific mental, physical, or substance-related causes. We hypothesized that the cellular energetic metabolites, including beta nucleoside triphosphate, which in magnetic resonance spectroscopy approximates adenosine triphosphate (ATP), and phosphocreatine (PCr), would show changes in PI reflecting increased energy demand. Design and Setting: Matched-groups, cross-sectional study performed at two university-based hospitals. Patients: Sixteen medication-free individuals (eight males, eight females; mean ± standard deviation (SD) age = 37.2 ± 8.4 y) with PI and 16 good sleepers (nine males, seven females; mean ± SD age = 37.6 ± 4.7 y). Measurements: Diagnosis was established for all individuals by unstructured clinical interview, Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID), sleep diary, and actigraphy. Polysomnography was collected in individuals with PI. Phosphorous magnetic resonance spectroscopy (31P MRS) data were collected on all individuals at 4 Tesla. We assessed cell membrane (anabolic precursors and catabolic metabolites) and bioenergetic (ATP, phosphocreatine) metabolites in gray matter and white matter to determine their relationship to the presence and severity of PI. Results: Individuals with PI showed lower phosphocreatine in gray matter and an unexpected decrease of phosphocholine, a precursor of the cell membrane compound phosphatidylcholine, in white matter. In addition, there was a trend toward a negative association between polysomnographically determined wake after sleep onset and gray matter beta-nucleoside triphosphate and white matter

  18. Is 3-Tesla Gd-EOB-DTPA-Enhanced MRI with Diffusion-Weighted Imaging Superior to 64-Slice Contrast-Enhanced CT for the Diagnosis of Hepatocellular Carcinoma?

    PubMed Central

    Maiwald, Bettina; Lobsien, Donald; Kahn, Thomas; Stumpp, Patrick

    2014-01-01

    Objectives To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting. Methods 3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm2. The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique. Results MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10−3 mm2/s (range from 0.07±0.1 to 3.0±0.1×10−3 mm2/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques. Conclusions Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so

  19. Signal-to-noise ratio and spectral linewidth improvements between 1.5 and 7 Tesla in proton echo-planar spectroscopic imaging.

    PubMed

    Otazo, Ricardo; Mueller, Bryon; Ugurbil, Kamil; Wald, Lawrence; Posse, Stefan

    2006-12-01

    This study characterizes gains in sensitivity and spectral resolution of proton echo-planar spectroscopic imaging (PEPSI) with increasing magnetic field strength (B(0)). Signal-to-noise ratio (SNR) per unit volume and unit time, and intrinsic linewidth (LW) of N-acetyl-aspartate (NAA), creatine (Cr), and choline (Cho) were measured with PEPSI at 1.5, 3, 4, and 7 Tesla on scanners that shared a similar software and hardware platform, using circularly polarized (CP) and eight-channel phased-array (PA) head coils. Data were corrected for relaxation effects and processed with a time-domain matched filter (MF) adapted to each B(0). The SNR and LW measured with PEPSI were very similar to those measured with conventional point-resolved spectroscopy (PRESS) SI. Measurements with the CP coil demonstrated a nearly linear SNR gain with respect to B(0) in central brain regions. For the PA coil, the SNR-B(0) relationship was less than linear, but there was a substantial SNR increase in comparison to the CP coil. The LW in units of ppm decreased with B(0), resulting in improved spectral resolution. These studies using PEPSI demonstrated linear gains in SNR with respect to B(0), consistent with theoretical expectations, and a decrease in ppm LW with increasing B(0).

  20. Topography of Cortical Microbleeds in Alzheimer's Disease with and without Cerebral Amyloid Angiopathy: A Post-Mortem 7.0-Tesla MRI Study.

    PubMed

    De Reuck, J; Auger, F; Durieux, N; Deramecourt, V; Cordonnier, C; Pasquier, F; Maurage, C A; Leys, D; Bordet, R

    2015-11-01

    Cortical microbleeds (CMBs) detected on T2*-weighted gradient-echo (GRE) magnetic resonance imaging (MRI) are considered as a possible hallmark of cerebral amyloid angiopathy (CAA). The present post-mortem 7.0-tesla MRI study investigates whether topographic differences exist in Alzheimer's brains without (AD) and with CAA (AD-CAA). The distribution of CMBs in thirty-two post-mortem brains, consisting of 12 AD, 8 AD-CAA and 12 controls, was mutually compared on T2*-GRE MRI of six coronal sections of a cerebral hemisphere. The mean numbers of CMBs were determined in twenty-two different gyri. As a whole there was a trend of more CMBs on GRE MRI in the prefrontal section of the AD, the AD-CAA as well as of the control brains. Compared to controls AD brains had significantly more CMBs in the superior frontal, the inferior temporal, the rectus and the cinguli gyrus, and in the insular cortex. In AD-CAA brains CMBs were increased in all gyri with exception of the medial parietal gyrus and the hippocampus. AD-CAA brains showed a highly significant increase of CMBs in the inferior parietal gyrus (p value: 0.001) and a significant increase in the precuneus and the cuneus (p value: 0.01) compared to the AD brains. The differences in topographic distribution of CMBs between AD and AD-CAA brains should be further investigated on MRI in clinically suspected patients.

  1. Is the Susceptibility Vessel Sign on 3-Tesla Magnetic Resonance T2*-Weighted Imaging a Useful Tool to Predict Recanalization in Intravenous Tissue Plasminogen Activator?

    PubMed

    Yamamoto, N; Satomi, J; Harada, M; Izumi, Y; Nagahiro, S; Kaji, R

    2016-09-01

    The aim of this study was to investigate the independent factors associated with the absence of recanalization approximately 24 h after intravenous administration of tissue-type plasminogen activator (IV TPA). The previous studies have been conducted using 1.5-Tesla (T) magnetic resonance imaging (MRI). We studied whether the characteristics of 3-T MRI findings were useful to predict outcome and recanalization after IV tPA. Patients with internal carotid artery (ICA) or middle cerebral artery (MCA) (horizontal portion, M1; Sylvian portion, M2) occlusion and treated by IV tPA were enrolled. We studied whether the presence of susceptibility vessel sign (SVS) at M1 and low clot burden score on T2*-weighted imaging (T2*-CBS) on 3-T MRI were associated with the absence of recanalization. A total of 49 patients were enrolled (27 men; mean age, 73.9 years). MR angiography obtained approximately 24 h after IV tPA revealed recanalization in 21 (42.9 %) patients. Independent factors associated with the absence of recanalization included ICA or proximal M1 occlusion (odds ratio, 69.6; 95 % confidence interval, 5.05-958.8, p = 0.002). In this study, an independent factor associated with the absence of recanalization may be proximal occlusion of the cerebral arteries rather than SVS in the MCA or low T2*-CBS on 3-T MRI.

  2. 7-Tesla Susceptibility-Weighted Imaging to Assess the Effects of Radiotherapy on Normal-Appearing Brain in Patients With Glioma

    SciTech Connect

    Lupo, Janine M.; Chuang, Cynthia F.; Chang, Susan M.; Barani, Igor J.; Jimenez, Bert; Hess, Christopher P.; Nelson, Sarah J.

    2012-03-01

    Purpose: To evaluate the intermediate- and long-term imaging manifestations of radiotherapy on normal-appearing brain tissue in patients with treated gliomas using 7T susceptibility-weighted imaging (SWI). Methods and Materials: SWI was performed on 25 patients with stable gliomas on a 7 Tesla magnet. Microbleeds were identified as discrete foci of susceptibility that did not correspond to vessels. The number of microbleeds was counted within and outside of the T2-hyperintense lesion. For 3 patients, radiation dosimetry maps were reconstructed and fused with the 7T SWI data. Results: Multiple foci of susceptibility consistent with microhemorrhages were observed in patients 2 years after chemoradiation. These lesions were not present in patients who were not irradiated. The prevalence of microhemorrhages increased with the time since completion of radiotherapy, and these lesions often extended outside the boundaries of the initial high-dose volume and into the contralateral hemisphere. Conclusions: High-field SWI has potential for visualizing the appearance of microbleeds associated with long-term effects of radiotherapy on brain tissue. The ability to visualize these lesions in normal-appearing brain tissue may be important in further understanding the utility of this treatment in patients with longer survival.

  3. FPGA technology application in a fast measurement and control system for the TESLA superconducting cavity of a FLASH free electron laser

    NASA Astrophysics Data System (ADS)

    Pozniak, Krzysztof T.

    2007-08-01

    Contemporary basic research in physics, biology, chemistry, pharmacology, material technology and other branches uses methods based on sample penetration (and the effect measurement) with pulsed ultra-short EM waves of very high beam intensity. This paper is an overview of a free electron laser (FEL) used in such methods. A method for the stabilization of the EM field in a superconducting 'TESLA' cavity accelerator for electrons is presented. This requires precise measurements of the field. The SC accelerator is a basic part of the FEL. The given example concerns the FLASH machine in DESY. The presented, high power EM field stabilization system is based on FPGA circuits with embedded fast hardware multiplication blocks. Examples of a few families of such new generation practically designed and constructed system realizations are given. The system is referred to as the SIMCON (from the microwave superconducting cavity SIMulator and CONtroller). SIMCONs consist of either single-module, multi-module configurable or multichannel distributed units. The SIMCON system stabilizes the EM field by a very fast feedback loop with an adaptation process, supplemented with a feed-forward. The following are presented: a parametric hardware description (firmware) in the form of behavioural VHDL algorithms; implementation results in VirtexIIPro circuits; examples of measurements of high power EM field stability performed under the nominal conditions of accelerator work.

  4. Assessment of safety and interference issues of radio frequency identification devices in 0.3 Tesla magnetic resonance imaging and computed tomography.

    PubMed

    Periyasamy, M; Dhanasekaran, R

    2014-01-01

    The objective of this study was to evaluate two issues regarding magnetic resonance imaging (MRI) including device functionality and image artifacts for the presence of radio frequency identification devices (RFID) in association with 0.3 Tesla at 12.7 MHz MRI and computed tomography (CT) scanning. Fifteen samples of RFID tags with two different sizes (wristband and ID card types) were tested. The tags were exposed to several MR-imaging conditions during MRI examination and X-rays of CT scan. Throughout the test, the tags were oriented in three different directions (axial, coronal, and sagittal) relative to MRI system in order to cover all possible situations with respect to the patient undergoing MRI and CT scanning, wearing a RFID tag on wrist. We observed that the tags did not sustain physical damage with their functionality remaining unaffected even after MRI and CT scanning, and there was no alternation in previously stored data as well. In addition, no evidence of either signal loss or artifact was seen in the acquired MR and CT images. Therefore, we can conclude that the use of this passive RFID tag is safe for a patient undergoing MRI at 0.3 T/12.7 MHz and CT Scanning.

  5. Aging and magnetism: Presenting a possible new holistic paradigm for ameliorating the aging process and the effects thereof, through externally applied physiologic PicoTesla magnetic fields.

    PubMed

    Jacobson, Jerry; Sherlag, Benjamin

    2015-09-01

    A new holistic paradigm is proposed for slowing our genomic-based biological clocks (e.g. regulation of telomere length), and decreasing heat energy exigencies for maintenance of physiologic homeostasis. Aging is considered the result of a progressive slow burn in small volumes of tissues with increase in the quantum entropic states; producing desiccation, microscopic scarring, and disruption of cooperative coherent states. Based upon piezoelectricity, i.e. photon-phonon transductions, physiologic PicoTesla range magnetic fields may decrease the production of excessive heat energy through target specific, bio molecular resonant interactions, renormalization of intrinsic electromagnetic tissue profiles, and autonomic modulation. Prospectively, we hypothesize that deleterious effects of physical trauma, immunogenic microbiological agents, stress, and anxiety may be ameliorated. A particle-wave equation is cited to ascertain magnetic field parameters for application to the whole organism thereby achieving desired homeostasis; secondary to restoration of structure and function on quantum levels. We hypothesize that it is at the atomic level that physical events shape the flow of signals and the transmission of energy in bio molecular systems. References are made to experimental data indicating the aspecific efficacy of non-ionizing physiologic magnetic field profiles for treatment of various pathologic states. PMID:26092501

  6. Aging and magnetism: Presenting a possible new holistic paradigm for ameliorating the aging process and the effects thereof, through externally applied physiologic PicoTesla magnetic fields.

    PubMed

    Jacobson, Jerry; Sherlag, Benjamin

    2015-09-01

    A new holistic paradigm is proposed for slowing our genomic-based biological clocks (e.g. regulation of telomere length), and decreasing heat energy exigencies for maintenance of physiologic homeostasis. Aging is considered the result of a progressive slow burn in small volumes of tissues with increase in the quantum entropic states; producing desiccation, microscopic scarring, and disruption of cooperative coherent states. Based upon piezoelectricity, i.e. photon-phonon transductions, physiologic PicoTesla range magnetic fields may decrease the production of excessive heat energy through target specific, bio molecular resonant interactions, renormalization of intrinsic electromagnetic tissue profiles, and autonomic modulation. Prospectively, we hypothesize that deleterious effects of physical trauma, immunogenic microbiological agents, stress, and anxiety may be ameliorated. A particle-wave equation is cited to ascertain magnetic field parameters for application to the whole organism thereby achieving desired homeostasis; secondary to restoration of structure and function on quantum levels. We hypothesize that it is at the atomic level that physical events shape the flow of signals and the transmission of energy in bio molecular systems. References are made to experimental data indicating the aspecific efficacy of non-ionizing physiologic magnetic field profiles for treatment of various pathologic states.

  7. Simulation of Time-Dependent Energy Modulation by Wake Fields and its Impact on Gain in the VUV free Electron Laser of the TESLA Test Facility

    NASA Astrophysics Data System (ADS)

    Reiche, S.; Schlarb, H.

    2000-05-01

    For shorter bunches and narrower undulator gaps the interaction between the electrons in the bunch and the wake fields becomes so large that the FEL amplification is affected. For a typical vacuum chamber of an X-ray or VUV Free Electron Laser three major sources of wake fields exist: a resistance of the beam pipe, a change in the geometric aperture and the surface roughness of the beam pipe. The generated wake fields, which move along with the electrons, change the electron energy and momentum, depending on the electron longitudinal and transverse position. In particular, the accumulated energy modulation shifts the electrons away from the resonance condition. Based on an analytic model the energy loss by the wake fields has been incorporated into the time-dependent FEL simulation code GENESIS 1.3. For the parameters of the TESLA Test Facility the influence of the bunch length, beam pipe diameter and surface roughness has been studied. The results are presented in this paper.

  8. Preliminary evidence for white matter metabolite differences in marijuana dependent young men using 2D J-resolved magnetic resonance spectroscopic imaging at 4 Tesla

    PubMed Central

    Silveri, Marisa M.; Jensen, J. Eric; Rosso, Isabelle M.; Sneider, Jennifer T.; Yurgelun-Todd, Deborah A.

    2010-01-01

    Chronic marijuana (MRJ) use is associated with altered cognition and mood state, altered brain metabolites, functional and structural brain changes. The objective of this study was to apply proton magnetic resonance spectroscopic imaging (MRSI) to compare proton metabolite levels in 15 young men with MRJ-dependence and 11 healthy non-using (NU) young men. Spectra were acquired at 4.0 Tesla using 2D J-resolved MRSI to resolve coupled resonances in J-space and to quantify the entire J-coupled spectral surface of metabolites from voxels containing basal ganglia and thalamus, temporal and parietal lobe, and occipital white and gray matter. This method permitted investigation of high-quality spectra for regression analyses to examine metabolites relative to tissue type. Distribution of myo-inositol (mI)/creatine (Cr) was altered in the MRJ group whereas the NU group exhibited higher mI/Cr in WM than GM, this pattern was not observed in MRJ subjects. Significant relationships observed between global mI/Cr and distribution in WM, and self-reported impulsivity and mood symptoms were also unique between MRJ and NU groups. These preliminary findings suggest that mI, and distribution of this glial metabolite in WM, is altered by MRJ use and is associated with behavioral and affective features reported by young MRJ-dependent men. PMID:21334181

  9. Signal-to-noise ratio and spectral linewidth improvements between 1.5 and 7 Tesla in proton echo-planar spectroscopic imaging.

    PubMed

    Otazo, Ricardo; Mueller, Bryon; Ugurbil, Kamil; Wald, Lawrence; Posse, Stefan

    2006-12-01

    This study characterizes gains in sensitivity and spectral resolution of proton echo-planar spectroscopic imaging (PEPSI) with increasing magnetic field strength (B(0)). Signal-to-noise ratio (SNR) per unit volume and unit time, and intrinsic linewidth (LW) of N-acetyl-aspartate (NAA), creatine (Cr), and choline (Cho) were measured with PEPSI at 1.5, 3, 4, and 7 Tesla on scanners that shared a similar software and hardware platform, using circularly polarized (CP) and eight-channel phased-array (PA) head coils. Data were corrected for relaxation effects and processed with a time-domain matched filter (MF) adapted to each B(0). The SNR and LW measured with PEPSI were very similar to those measured with conventional point-resolved spectroscopy (PRESS) SI. Measurements with the CP coil demonstrated a nearly linear SNR gain with respect to B(0) in central brain regions. For the PA coil, the SNR-B(0) relationship was less than linear, but there was a substantial SNR increase in comparison to the CP coil. The LW in units of ppm decreased with B(0), resulting in improved spectral resolution. These studies using PEPSI demonstrated linear gains in SNR with respect to B(0), consistent with theoretical expectations, and a decrease in ppm LW with increasing B(0). PMID:17094090

  10. Assessment of Age-Related Morphometric Changes of Subcortical Structures in Healthy People Using Ultra-High Field 7 Tesla Magnetic Resonance Imaging

    PubMed Central

    Wang, Xue-Yuan; Zhao, Lei; Yu, Tao; Qiao, Liang; Ni, Duan-Yu; Zhang, Guo-Jun; Li, Yong-Jie

    2016-01-01

    Objective: To assess the age-related morphometric changes of subcortical structures in healthy people. Materials and Methods: Ultra-high field 7 tesla magnetic resonance (MR) imaging in humans was used to visualize the subcortical structures of healthy young, middle-aged and elderly participants. Using the magnetization-prepared two rapid acquisition gradient echo (MP2RAGE) sequence, we assessed the visibility of the margins of the thalamus and white matter in the thalamus, as well as the anterior commissure (AC) and posterior commissure (PC) length, the maximal height of the thalamus, the half width of the third ventricle and the distance between the AC and the center of the mammillothalamic tract (MTT) at the level of the AC-PC plane. All quantitative data were statistically evaluated. Results: The AC-PC length did not differ significantly among the three groups. The maximal height of the thalamus decreased with age (rs(53) = −0.719, p < 0.001). The half width of the third ventricle (rs(53) = 0.705, p < 0.001) and the distance between the AC and the center of the MTT (rs(53) = 0.485, p < 0.001) increased with age. The distance between the AC and the center of the MTT of the young and the elderly participants differed significantly (p = 0.007). Conclusion: The AC-PC length is not a good candidate for proportional correction during atlas-to-patient registration. The maximal height of the thalamus and the half width of the third ventricle correlated strongly with age, and the MTT position in relation to the AC shifted posteriorly as age increased. These age-related morphometric changes of subcortical structures should be considered in targeting for functional neurosurgery. PMID:27725800

  11. An ecophysiological study of plants growing on the fly ash deposits from the "Nikola Tesla-A" thermal power station in Serbia.

    PubMed

    Pavlović, Pavle; Mitrović, Miroslava; Djurdjević, Lola

    2004-05-01

    This ecophysiological research on the ash deposits from the "Nikola Tesla-A" thermal power station in Serbia covered 10 plant species (Tamarix gallica, Populus alba, Spiraea van-hauttei, Ambrosia artemisifolia, Amorpha fruticosa, Eupatorium cannabinum, Crepis setosa, Epilobium collinum, Verbascum phlomoides, and Cirsium arvense). This paper presents the results of a water regime analysis, photosynthetic efficiency and trace elements (B, Cu, Mn, Zn, Pb, and Cd) content in vegetative plant parts. Water regime parameters indicate an overall stability in plant-water relations. During the period of summer drought, photosynthetic efficiency (Fv/Fm) was low, ranging from 0.429 to 0.620 for all the species that were analyzed. An analysis of the tissue trace elements content showed a lower trace metal concentration in the plants than in the ash, indicating that heavy metals undergo major concentration during the combustion process and some are not readily taken up by plants. The Zn and Pb concentrations in all of the examined species were normal whereas Cu and Mn concentrations were in the deficiency range. Boron concentrations in plant tissues were high, with some species even showing levels of more than 100 microg/g (Populus sp., Ambrosia sp., Amorpha sp., and Cirsium sp.). The presence of Cd was not detected. In general, it can be concluded from the results of this research that biological recultivation should take into account the existing ecological, vegetation, and floristic potential of an immediate environment that is abundant in life forms and ecological types of plant species that can overgrow the ash deposit relatively quickly. Selected species should be adapted to toxic B concentrations with moderate demands in terms of mineral elements (Cu and Mn). PMID:15503386

  12. An ecophysiological study of plants growing on the fly ash deposits from the "Nikola Tesla-A" thermal power station in Serbia.

    PubMed

    Pavlović, Pavle; Mitrović, Miroslava; Djurdjević, Lola

    2004-05-01

    This ecophysiological research on the ash deposits from the "Nikola Tesla-A" thermal power station in Serbia covered 10 plant species (Tamarix gallica, Populus alba, Spiraea van-hauttei, Ambrosia artemisifolia, Amorpha fruticosa, Eupatorium cannabinum, Crepis setosa, Epilobium collinum, Verbascum phlomoides, and Cirsium arvense). This paper presents the results of a water regime analysis, photosynthetic efficiency and trace elements (B, Cu, Mn, Zn, Pb, and Cd) content in vegetative plant parts. Water regime parameters indicate an overall stability in plant-water relations. During the period of summer drought, photosynthetic efficiency (Fv/Fm) was low, ranging from 0.429 to 0.620 for all the species that were analyzed. An analysis of the tissue trace elements content showed a lower trace metal concentration in the plants than in the ash, indicating that heavy metals undergo major concentration during the combustion process and some are not readily taken up by plants. The Zn and Pb concentrations in all of the examined species were normal whereas Cu and Mn concentrations were in the deficiency range. Boron concentrations in plant tissues were high, with some species even showing levels of more than 100 microg/g (Populus sp., Ambrosia sp., Amorpha sp., and Cirsium sp.). The presence of Cd was not detected. In general, it can be concluded from the results of this research that biological recultivation should take into account the existing ecological, vegetation, and floristic potential of an immediate environment that is abundant in life forms and ecological types of plant species that can overgrow the ash deposit relatively quickly. Selected species should be adapted to toxic B concentrations with moderate demands in terms of mineral elements (Cu and Mn).

  13. High resolution spectroscopy and chemical shift imaging of hyperpolarized 129Xe dissolved in the human brain in vivo at 1.5 tesla

    PubMed Central

    Rao, Madhwesha; Stewart, Neil J.; Norquay, Graham; Griffiths, Paul D.

    2016-01-01

    Purpose Upon inhalation, xenon diffuses into the bloodstream and is transported to the brain, where it dissolves in various compartments of the brain. Although up to five chemically distinct peaks have been previously observed in 129Xe rat head spectra, to date only three peaks have been reported in the human head. This study demonstrates high resolution spectroscopy and chemical shift imaging (CSI) of 129Xe dissolved in the human head at 1.5 Tesla. Methods A 129Xe radiofrequency coil was built in‐house and 129Xe gas was polarized using spin‐exchange optical pumping. Following the inhalation of 129Xe gas, NMR spectroscopy was performed with spectral resolution of 0.033 ppm. Two‐dimensional CSI in all three anatomical planes was performed with spectral resolution of 2.1 ppm and voxel size 20 mm × 20 mm. Results Spectra of hyperpolarized 129Xe dissolved in the human head showed five distinct peaks at 188 ppm, 192 ppm, 196 ppm, 200 ppm, and 217 ppm. Assignment of these peaks was consistent with earlier studies. Conclusion High resolution spectroscopy and CSI of hyperpolarized 129Xe dissolved in the human head has been demonstrated. For the first time, five distinct NMR peaks have been observed in 129Xe spectra from the human head in vivo. Magn Reson Med 75:2227–2234, 2016. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:27080441

  14. Preoperative 3-Tesla Multiparametric Endorectal Magnetic Resonance Imaging Findings and the Odds of Upgrading and Upstaging at Radical Prostatectomy in Men With Clinically Localized Prostate Cancer

    SciTech Connect

    Hegde, John V.; Chen, Ming-Hui; Mulkern, Robert V.; Fennessy, Fiona M.; D'Amico, Anthony V.; Tempany, Clare M.C.

    2013-02-01

    Purpose: To investigate whether 3-T esla (3T) multiparametric endorectal MRI (erMRI) can add information to established predictors regarding occult extraprostatic or high-grade prostate cancer (PC) in men with clinically localized PC. Methods and Materials: At a single academic medical center, this retrospective study's cohort included 118 men with clinically localized PC who underwent 3T multiparametric erMRI followed by radical prostatectomy, from 2008 to 2011. Multivariable logistic regression analyses in all men and in 100 with favorable-risk PC addressed whether erMRI evidence of T3 disease was associated with prostatectomy T3 or Gleason score (GS) 8-10 (in patients with biopsy GS {<=}7) PC, adjusting for age, prostate-specific antigen level, clinical T category, biopsy GS, and percent positive biopsies. Results: The accuracy of erMRI prediction of extracapsular extension and seminal vesicle invasion was 75% and 95%, respectively. For all men, erMRI evidence of a T3 lesion versus T2 was associated with an increased odds of having pT3 disease (adjusted odds ratio [AOR] 4.81, 95% confidence interval [CI] 1.36-16.98, P=.015) and pGS 8-10 (AOR 5.56, 95% CI 1.10-28.18, P=.038). In the favorable-risk population, these results were AOR 4.14 (95% CI 1.03-16.56), P=.045 and AOR 7.71 (95% CI 1.36-43.62), P=.021, respectively. Conclusions: Three-Tesla multiparametric erMRI in men with favorable-risk PC provides information beyond that contained in known preoperative predictors about the presence of occult extraprostatic and/or high-grade PC. If validated in additional studies, this information can be used to counsel men planning to undergo radical prostatectomy or radiation therapy about the possible need for adjuvant radiation therapy or the utility of adding hormone therapy, respectively.

  15. Suppression of skeletal muscle signal using a crusher coil: A human cardiac 31p‐MR spectroscopy study at 7 tesla

    PubMed Central

    Clarke, William T.; Neubauer, Stefan; Robson, Matthew D.; Rodgers, Christopher T.

    2015-01-01

    Purpose The translation of sophisticated phosphorus MR spectroscopy (31P‐MRS) protocols to 7 Tesla (T) is particularly challenged by the issue of radiofrequency (RF) heating. Legal limits on RF heating make it hard to reliably suppress signals from skeletal muscle that can contaminate human cardiac 31P spectra at 7T. We introduce the first surface‐spoiling crusher coil for human cardiac 31P‐MRS at 7T. Methods A planar crusher coil design was optimized with simulations and its performance was validated in phantoms. Crusher gradient pulses (100 μs) were then applied during human cardiac 31P‐MRS at 7T. Results In a phantom, residual signals were 50 ± 10% with BISTRO (B1‐insensitive train to obliterate signal), and 34 ± 8% with the crusher coil. In vivo, residual signals in skeletal muscle were 49 ± 4% using BISTRO, and 24 ± 5% using the crusher coil. Meanwhile, in the interventricular septum, spectral quality and metabolite quantification did not differ significantly between BISTRO (phosphocreatine/adenosine triphosphate [PCr/ATP] = 2.1 ± 0.4) and the crusher coil (PCr/ATP = 1.8 ± 0.4). However, the specific absorption rate (SAR) decreased from 96 ± 1% of the limit (BISTRO) to 16 ± 1% (crusher coil). Conclusion A crusher coil is an SAR‐efficient alternative for selectively suppressing skeletal muscle during cardiac 31P‐MRS at 7T. A crusher coil allows the use of sequence modules that would have been SAR‐prohibitive, without compromising skeletal muscle suppression. Magn Reson Med 75:962–972, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. PMID:25924813

  16. Development of Brain Structural Connectivity between Ages 12 and 30: A 4-Tesla Diffusion Imaging Study in 439 Adolescents and Adults

    PubMed Central

    Dennis, Emily L.; Jahanshad, Neda; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Hickie, Ian B.; Toga, Arthur W.; Wright, Margaret J.; Thompson, Paul M.

    2013-01-01

    Understanding how the brain matures in healthy individuals is critical for evaluating deviations from normal development in psychiatric and neurodevelopmental disorders. The brain’s anatomical networks are profoundly re-modeled between childhood and adulthood, and diffusion tractography offers unprecedented power to reconstruct these networks and neural pathways in vivo. Here we tracked changes in structural connectivity and network efficiency in 439 right-handed individuals aged 12 to 30 (211 female/126 male adults, mean age=23.6, SD=2.19; 31 female/24 male 12 year olds, mean age=12.3, SD=0.18; and 25 female/22 male 16 year olds, mean age=16.2, SD=0.37). All participants were scanned with high angular resolution diffusion imaging (HARDI) at 4 Tesla. After we performed whole brain tractography, 70 cortical gyral-based regions of interest were extracted from each participant’s co-registered anatomical scans. The degree of fiber connections between all pairs of cortical regions, or nodes, were found to create symmetric fiber density matrices, reflecting the structural brain network. From those 70×70 matrices we computed graph theory metrics characterizing structural connectivity. Several key global and nodal metrics changed across development, showing increased network integration, with some connections pruned and others strengthened. The increases and decreases in fiber density, however, were not distributed proportionally across the brain. The frontal cortex had a disproportionate number of decreases in fiber density while the temporal cortex had a disproportionate number of increases in fiber density. This large-scale analysis of the developing structural connectome offers a foundation to develop statistical criteria for aberrant brain connectivity as the human brain matures. PMID:22982357

  17. Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5–7 Tesla MRI scanners is associated with reporting of transient symptoms

    PubMed Central

    Schaap, Kristel; Christopher-de Vries, Yvette; Mason, Catherine K; de Vocht, Frank; Portengen, Lützen; Kromhout, Hans

    2014-01-01

    Objectives Limited data is available about incidence of acute transient symptoms associated with occupational exposure to static magnetic stray fields from MRI scanners. We aimed to assess the incidence of these symptoms among healthcare and research staff working with MRI scanners, and their association with static magnetic field exposure. Methods We performed an observational study among 361 employees of 14 clinical and research MRI facilities in The Netherlands. Each participant completed a diary during one or more work shifts inside and/or outside the MRI facility, reporting work activities and symptoms (from a list of potentially MRI-related symptoms, complemented with unrelated symptoms) experienced during a working day. We analysed 633 diaries. Exposure categories were defined by strength and type of MRI scanner, using non-MRI shifts as the reference category for statistical analysis. Non-MRI shifts originated from MRI staff who also participated on MRI days, as well as CT radiographers who never worked with MRI. Results Varying per exposure category, symptoms were reported during 16–39% of the MRI work shifts. We observed a positive association between scanner strength and reported symptoms among healthcare and research staff working with closed-bore MRI scanners of 1.5 Tesla (T) and higher (1.5 T OR=1.88; 3.0 T OR=2.14; 7.0 T OR=4.17). This finding was mainly driven by reporting of vertigo and metallic taste. Conclusions The results suggest an exposure-response association between exposure to strong static magnetic fields (and associated motion-induced time-varying magnetic fields) and reporting of transient symptoms on the same day of exposure. Trial registration number 11-032/C PMID:24714654

  18. Comparison of Gross Body Fat-Water Magnetic Resonance Imaging at 3 Tesla to Dual Energy X-Ray Absorptiometry in Obese Women

    PubMed Central

    Silver, HJ; Niswender, KD; Kullberg, J; Berglund, J; Johansson, L; Bruvold, M; Avison, MJ; Welch, EB.

    2012-01-01

    Improved understanding of how depot-specific adipose tissue mass predisposes to obesity-related comorbidities could yield new insights into the pathogenesis and treatment of obesity as well as metabolic benefits of weight loss. We hypothesized that three-dimensional contiguous “fat-water” MR imaging (FWMRI) covering the majority of a whole-body field of view (FOV) acquired at 3 Tesla (3T) and coupled with automated segmentation and quantification of amount, type and distribution of adipose and lean soft tissue would show great promise in body composition methodology. Precision of adipose and lean soft tissue measurements in body and trunk regions were assessed for 3T FWMRI and compared to DEXA. Anthropometric, FWMRI and DEXA measurements were obtained in twelve women with BMI 30–39.9 kg/m2. Test-retest results found coefficients of variation for FWMRI that were all under 3%: gross body adipose tissue (GBAT) 0.80%, total trunk adipose tissue (TTAT) 2.08%, visceral adipose tissue (VAT) 2.62%, subcutaneous adipose tissue (SAT) 2.11%, gross body lean soft tissue (GBLST) 0.60%, and total trunk lean soft tissue (TTLST) 2.43%. Concordance correlation coefficients between FWMRI and DEXA were 0.978, 0.802, 0.629, and 0.400 for GBAT, TTAT, GBLST and TTLST, respectively. While Bland Altman plots demonstrated agreement between FWMRI and DEXA for GBAT and TTAT, a negative bias existed for GBLST and TTLST measurements. Differences may be explained by the FWMRI FOV length and potential for DEXA to overestimate lean soft tissue. While more development is necessary, the described 3T FWMRI method combined with fully-automated segmentation is fast (<30 minutes total scan and post-processing time), noninvasive, repeatable and cost effective. PMID:23712980

  19. Evaluation of the partial flip angle spin echo method to improve non-uniformity in T1-weighted imaging with the 3-tesla MRI

    NASA Astrophysics Data System (ADS)

    Watanabe, Youhei; Tsuzaka, Masatoshi; Ishibashi, Kazuto; Sakurai, Yasuo

    2008-03-01

    The higher signal-to-noise ratio (SNR) of 3-Tesla magnetic resonance imaging (3T MRI) contributes to an improvement in the spatial and temporal resolution. However, T1-weighted images of the brain obtained by the spin-echo (SE) method using 3T MRI are unsuitable for clinical use because of the inhomogeneity of the radio frequency (RF) field B1 non-uniformity. And it is clear by SE method. In addition, the prolongation of the longitudinal relaxation time (T1) of most tissues leads to a decrease in the T1 contrast. Therefore, many hospitals that utilize 3TMRI use the GRE method instead of the SE method in order to obtain an adequate T1 contrast, as can be obtained using FLASH (fast low angle shot), and high uniformity of images. Further, many studies have been performed to improve the non uniformity using techniques such as spatial presaturation. However, when filters are used, the high intensity of the influence in susceptible regions, signal deficits, and original contrast are lost, and a distortion can be clearly observed when the GRE method is used. Therefore, we obtained the T1-weighted images by using the partial flip angle SE method instead of the GRE method or SE method. We attempted to improve the image non-uniformity by using the partial flip angle SE method. Using this method, we could improve the image uniformity and also realize an adequate T1 contrast. As a result, the uniformity was found to improve by 6% and it became 82.6% at 110°. These results indicate that the use of the partial flip angle SE method is effective for obtaining adequate uniformity in the T1-weighted images of the brain.

  20. Whole-body diffusion-weighted magnetic resonance imaging at 3 Tesla for early assessment of treatment response in non-Hodgkin lymphoma: a pilot study

    PubMed Central

    De Paepe, Katja; Bevernage, Charlotte; De Keyzer, Frederik; Wolter, Pascal; Gheysens, Olivier; Janssens, Ann; Oyen, Raymond; Verhoef, Gregor

    2013-01-01

    Abstract Objective: To evaluate 3 Tesla (T) whole-body diffusion-weighted magnetic resonance imaging (WB DWI) for early treatment assessment in aggressive non-Hodgkin lymphoma (NHL). Methods: Fourteen patients with NHL treated with standard chemotherapy underwent 3-T WB DWI before and 2 and 4 weeks during treatment, using b-values of 0–1000 s/mm2 from which the apparent diffusion coefficient (ADC) was calculated. Patient follow-up (average 20.3 months, range 15–23 months) was the reference standard. Volume and ADC changes between baseline and 2 weeks (Vratio2w, ADCratio2w) and 4 weeks (Vratio4w, ADCratio4w) of responding and non-responding lesions (lymph node and organ lesions) were compared using Mann–Whitney U tests. The per patient values of VratioN and ADCratioN to predict progression-free survival were determined with a log-rank test. Results: Eight patients showed complete remission and 6 showed tumour progression. The ADCratio2w and ADCratio4w differed significantly in lesions showing tumour progression versus complete remission (ADCratio2w = 4 ± 21% versus 119 ± 68%; ADCratio4w = 18 ± 61% versus 155 ± 78%; both P < 0.0001); the Vratio2w and Vratio4w did not (P > 0.05). Per body region, the ADCratio2w showed a negative predictive value of 100% and positive predictive value of 86%. Per patient, the ADCratio2w and ADCratio4w correlated significantly with progression-free survival (P < 0.05). Conclusion: 3-T WB DWI with ADC quantification may enable early treatment assessment of aggressive NHL. PMID:23466737

  1. Development of Cerebral Microbleeds in the APP23-Transgenic Mouse Model of Cerebral Amyloid Angiopathy—A 9.4 Tesla MRI Study

    PubMed Central

    Reuter, Björn; Venus, Alexander; Heiler, Patrick; Schad, Lothar; Ebert, Anne; Hennerici, Michael G.; Grudzenski, Saskia; Fatar, Marc

    2016-01-01

    Background: Cerebral amyloid angiopathy (CAA) is characterized by extracellular deposition of amyloid β (Aβ) around cerebral arteries and capillaries and leads to an increased risk for vascular dementia, spontaneous lobar hemorrhage, convexal subarachnoid hemorrhage, and transient focal neurological episodes, which might be an indicator of imminent spontaneous intracerebral hemorrhage. In CAA cerebral microbleeds (cMBs) with a cortical/juxtacortical distribution are frequently observed in standard magnetic resonance imaging (MRI). In vivo MRI of transgenic mouse models of CAA may serve as a useful tool to investigate translational aspects of the disease. Materials and Methods: APP23-transgenic mice demonstrate cerebrovascular Aβ deposition with subsequent neuropathological changes characteristic for CAA. We performed a 9.4 Tesla high field MRI study using T2, T2* and time of flight-magnetic resonance angiograpy (TOF-MRA) sequences in APP23-transgenic mice and wildtype (wt) littermates at the age of 8, 12, 16, 20 and 24 months, respectively. Numbers, size, and location of cMBs are reported. Results: T2* imaging demonstrated cMBs (diameter 50–300 μm) located in the neocortex and, to a lesser degree, in the thalamus. cMBs were detected at the earliest at 16 months of age. Numbers increased exponentially with age, with 2.5 ± 2 (median ± interquartilrange) at 16 months, 15 ± 6 at 20 months, and 31.5 ± 17 at 24 months of age, respectively. Conclusion: We report the temporal and spatial development of cMBs in the aging APP23-transgenic mouse model which develops characteristic pathological patterns known from human CAA. We expect this mouse model to serve as a useful tool to non-invasively monitor mid- and longterm translational aspects of CAA and to investigate experimental therapeutic strategies in longitudinal studies. PMID:27458375

  2. A Wire Position Monitor System for the 1.3 FHZ Tesla-Style Cryomodule at the Fermilab New-Muon-Lab Accelerator

    SciTech Connect

    Eddy, N.; Fellenz, B.; Prieto, P.; Semenov, A.; Voy, D.C.; Wendt, M.; /Fermilab

    2011-08-17

    The first cryomodule for the beam test facility at the Fermilab New-Muon-Lab building is currently under RF commissioning. Among other diagnostics systems, the transverse position of the helium gas return pipe with the connected 1.3 GHz SRF accelerating cavities is measured along the {approx}15 m long module using a stretched-wire position monitoring system. An overview of the wire position monitor system technology is given, along with preliminary results taken at the initial module cooldown, and during further testing. As the measurement system offers a high resolution, we also discuss options for use as a vibration detector. An electron beam test facility, based on superconducting RF (SRF) TESLA-style cryomodules is currently under construction at the Fermilab New-Muon-Lab (NML) building. The first, so-called type III+, cryomodule (CM-1), equipped with eight 1.3 GHz nine-cell accelerating cavities was recently cooled down to 2 K, and is currently under RF conditioning. The transverse alignment of the cavity string within the cryomodule is crucial for minimizing transverse kick and beam break-up effects, generated by the high-order dipole modes of misaligned accelerating structures. An optimum alignment can only be guaranteed during the assembly of the cavity string, i.e. at room temperatures. The final position of the cavities after cooldown is uncontrollable, and therefore unknown. A wire position monitoring system (WPM) can help to understand the transverse motion of the cavities during cooldown, their final location and the long term position stability after cryo-temperatures are settled, as well as the position reproducibility for several cold-warm cycles. It also may serve as vibration sensor, as the wire acts as a high-Q resonant detector for mechanical vibrations in the low-audio frequency range. The WPM system consists out of a stretched-wire position detection system, provided with help of INFN-Milano and DESY Hamburg, and RF generation and read

  3. A study-specific fMRI normalization approach that operates directly on high resolution functional EPI data at 7 Tesla.

    PubMed

    Grabner, Günther; Poser, Benedikt A; Fujimoto, Kyoko; Polimeni, Jonathan R; Wald, Lawrence L; Trattnig, Siegfried; Toni, Ivan; Barth, Markus

    2014-10-15

    Due to the availability of ultra-high field scanners and novel imaging methods, high resolution, whole brain functional MR imaging (fMRI) has become increasingly feasible. However, it is common to use extensive spatial smoothing to account for inter-subject anatomical variation when pooling over subjects. This reduces the spatial details of group level functional activation considerably, even when the original data was acquired with high resolution. In our study we used an accelerated 3D EPI sequence at 7 Tesla to acquire whole brain fMRI data with an isotropic spatial resolution of 1.1mm which shows clear gray/white matter contrast due to the stronger T1 weighting of 3D EPI. To benefit from the high spatial resolution on the group level, we develop a study specific, high resolution anatomical template which is facilitated by the good anatomical contrast that is present in the average functional EPI images. Different template generations with increasing accuracy were created by using a hierarchical linear and stepwise non-linear registration approach. As the template is based on the functional data themselves no additional co-registration step with the usual T1-weighted anatomical data is necessary which eliminates a potential source of misalignment. To test the improvement of functional localization and spatial details we performed a group level analysis of a finger tapping experiment in eight subjects. The most accurate template shows better spatial localization--such as a separation of somatosensory and motor areas and of single digit activation--compared to the simple linear registration. The number of activated voxels is increased by a factor of 1.2, 2.5, and 3.1 for somatosensory, supplementary motor area, and dentate nucleus, respectively, for the functional contrast between left versus right hand. Similarly, the number of activated voxels is increased 1.4- and 2.4-fold for right little versus right index finger and left little versus left index finger

  4. [Reduction of vascular artifact on T1-weighted images of the brain by using three-dimensional double IR fast spoiled gradient echo recalled acquisition in the steady state (FSPGR) at 3.0 Tesla].

    PubMed

    Fujiwara, Yasuhiro; Matsuda, Tsuyoshi; Ishimori, Yoshiyuki; Yamaguchi, Isao; Hayashi, Hiroyuki; Ookoshi, Yusuke; Ootani, Yuriko; Miyati, Tosiaki; Kimura, Hirohiko

    2007-11-20

    The purpose of this study was to decrease vascular artifacts caused by the in-flow effect in three-dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady state (3D IR FSPGR) at 3.0 Tesla. We developed 3D double IR FSPGR and investigated the signal characteristics of the new sequence. The 3D double IR FSPGR sequence uses two inversion pulses, the first for obtaining tissue contrast and the second for nulling vascular signal, which is applied at the time of the first IR period at the neck region. We have optimized scan parameters based on both phantom and in-vivo study. As a result, optimized parameters (1st TI=700 ms, 2nd TI=400 ms) successfully have produced much less vessel signal at reduction than conventional 3D IR FSPGR over a wide imaging range, while preserving the signal-to-noise ratio (SNR) and gray/white matter contrast. Moreover, the decreased artifact was also confirmed by visual inspection of the images obtained in vivo using those parameters. Thus, 3D double IR FSPGR was a useful sequence for the acquisition of T1-weighted images at 3.0 Tesla.

  5. Resection and Resolution of Bone Marrow Lesions Associated with an Improvement of Pain after Total Knee Replacement: A Novel Case Study Using a 3-Tesla Metal Artefact Reduction MRI Sequence.

    PubMed

    Kurien, Thomas; Kerslake, Robert; Haywood, Brett; Pearson, Richard G; Scammell, Brigitte E

    2016-01-01

    We present our case report using a novel metal artefact reduction magnetic resonance imaging (MRI) sequence to observe resolution of subchondral bone marrow lesions (BMLs), which are strongly associated with pain, in a patient after total knee replacement surgery. Large BMLs were seen preoperatively on the 3-Tesla MRI scans in a patient with severe end stage OA awaiting total knee replacement surgery. Twelve months after surgery, using a novel metal artefact reduction MRI sequence, we were able to visualize the bone-prosthesis interface and found complete resection and resolution of these BMLs. This is the first reported study in the UK to use this metal artefact reduction MRI sequence at 3-Tesla showing that resection and resolution of BMLs in this patient were associated with an improvement of pain and function after total knee replacement surgery. In this case it was associated with a clinically significant improvement of pain and function after surgery. Failure to eradicate these lesions may be a cause of persistent postoperative pain that is seen in up to 20% of patients following TKR surgery.

  6. Resection and Resolution of Bone Marrow Lesions Associated with an Improvement of Pain after Total Knee Replacement: A Novel Case Study Using a 3-Tesla Metal Artefact Reduction MRI Sequence

    PubMed Central

    Haywood, Brett; Pearson, Richard G.; Scammell, Brigitte E.

    2016-01-01

    We present our case report using a novel metal artefact reduction magnetic resonance imaging (MRI) sequence to observe resolution of subchondral bone marrow lesions (BMLs), which are strongly associated with pain, in a patient after total knee replacement surgery. Large BMLs were seen preoperatively on the 3-Tesla MRI scans in a patient with severe end stage OA awaiting total knee replacement surgery. Twelve months after surgery, using a novel metal artefact reduction MRI sequence, we were able to visualize the bone-prosthesis interface and found complete resection and resolution of these BMLs. This is the first reported study in the UK to use this metal artefact reduction MRI sequence at 3-Tesla showing that resection and resolution of BMLs in this patient were associated with an improvement of pain and function after total knee replacement surgery. In this case it was associated with a clinically significant improvement of pain and function after surgery. Failure to eradicate these lesions may be a cause of persistent postoperative pain that is seen in up to 20% of patients following TKR surgery.

  7. Resection and Resolution of Bone Marrow Lesions Associated with an Improvement of Pain after Total Knee Replacement: A Novel Case Study Using a 3-Tesla Metal Artefact Reduction MRI Sequence

    PubMed Central

    Haywood, Brett; Pearson, Richard G.; Scammell, Brigitte E.

    2016-01-01

    We present our case report using a novel metal artefact reduction magnetic resonance imaging (MRI) sequence to observe resolution of subchondral bone marrow lesions (BMLs), which are strongly associated with pain, in a patient after total knee replacement surgery. Large BMLs were seen preoperatively on the 3-Tesla MRI scans in a patient with severe end stage OA awaiting total knee replacement surgery. Twelve months after surgery, using a novel metal artefact reduction MRI sequence, we were able to visualize the bone-prosthesis interface and found complete resection and resolution of these BMLs. This is the first reported study in the UK to use this metal artefact reduction MRI sequence at 3-Tesla showing that resection and resolution of BMLs in this patient were associated with an improvement of pain and function after total knee replacement surgery. In this case it was associated with a clinically significant improvement of pain and function after surgery. Failure to eradicate these lesions may be a cause of persistent postoperative pain that is seen in up to 20% of patients following TKR surgery. PMID:27648327

  8. Resection and Resolution of Bone Marrow Lesions Associated with an Improvement of Pain after Total Knee Replacement: A Novel Case Study Using a 3-Tesla Metal Artefact Reduction MRI Sequence.

    PubMed

    Kurien, Thomas; Kerslake, Robert; Haywood, Brett; Pearson, Richard G; Scammell, Brigitte E

    2016-01-01

    We present our case report using a novel metal artefact reduction magnetic resonance imaging (MRI) sequence to observe resolution of subchondral bone marrow lesions (BMLs), which are strongly associated with pain, in a patient after total knee replacement surgery. Large BMLs were seen preoperatively on the 3-Tesla MRI scans in a patient with severe end stage OA awaiting total knee replacement surgery. Twelve months after surgery, using a novel metal artefact reduction MRI sequence, we were able to visualize the bone-prosthesis interface and found complete resection and resolution of these BMLs. This is the first reported study in the UK to use this metal artefact reduction MRI sequence at 3-Tesla showing that resection and resolution of BMLs in this patient were associated with an improvement of pain and function after total knee replacement surgery. In this case it was associated with a clinically significant improvement of pain and function after surgery. Failure to eradicate these lesions may be a cause of persistent postoperative pain that is seen in up to 20% of patients following TKR surgery. PMID:27648327

  9. Molecular imaging of angiogenesis in nascent Vx-2 rabbit tumors using a novel alpha(nu)beta3-targeted nanoparticle and 1.5 tesla magnetic resonance imaging.

    PubMed

    Winter, Patrick M; Caruthers, Shelton D; Kassner, Andrea; Harris, Thomas D; Chinen, Lori K; Allen, John S; Lacy, Elizabeth K; Zhang, Huiying; Robertson, J David; Wickline, Samuel A; Lanza, Gregory M

    2003-09-15

    leaky tumor neovasculature but did not appreciably migrate into the interstitium, leading to a 56% increase in MR signal at 2 h. Pretargeting of the alpha(nu)beta(3)-integrin with nonparamagnetic nanoparticles competitively blocked the specific binding of alpha(nu)beta(3)-targeted paramagnetic nanoparticles, decreasing the MR signal enhancement (50%) to a level attributable to local extravasation. The MR signal of adjacent hindlimb muscle or contralateral control tissues was unchanged by either the alpha(nu)beta(3)-targeted or control paramagnetic agents. Immunohistochemistry of alpha(nu)beta(3)-integrin corroborated the extent and asymmetric distribution of neovascularity observed by MRI. These studies demonstrate the potential of this targeted molecular imaging agent to detect and characterize (both biochemically and morphologically) early angiogenesis induced by minute solid tumors with a clinical 1.5 Tesla MRI scanner, facilitating the localization of nascent cancers or metastases, as well as providing tools to phenotypically categorize and segment patient populations for therapy and to longitudinally follow the effectiveness of antitumor treatment regimens.

  10. The Role of 3 Tesla Diffusion-Weighted Imaging in the Differential Diagnosis of Benign versus Malignant Cervical Lymph Nodes in Patients with Head and Neck Squamous Cell Carcinoma

    PubMed Central

    Pranno, Nicola; Sartori, Alessandro; Gigli, Silvia; Lo Mele, Luigi; Marsella, Luigi Tonino

    2014-01-01

    Objective. The aim of this study was to validate the role of diffusion-weighted imaging (DWI) at 3 Tesla in the differential diagnosis between benign and malignant laterocervical lymph nodes in patients with head and neck squamous cell carcinoma (HNSCC). Materials and Methods. Before undergoing surgery, 80 patients, with biopsy proven HNSCC, underwent a magnetic resonance exam. Sensitivity (Se) and specificity (Spe) of conventional criteria and DWI in detecting laterocervical lymph node metastases were calculated. Histological results from neck dissection were used as standard of reference. Results. In the 239 histologically proven metastatic lymphadenopathies, the mean apparent diffusion coefficient (ADC) value was 0.903 × 10−3 mm2/sec. In the 412 pathologically confirmed benign lymph nodes, an average ADC value of 1.650 × 10−3 mm2/sec was found. For differentiating between benign versus metastatic lymph nodes, DWI showed Se of 97% and Spe of 93%, whereas morphological criteria displayed Se of 61% and Spe of 98%. DWI showed an area under the ROC curve (AUC) of 0.964, while morphological criteria displayed an AUC of 0.715. Conclusions. In a DWI negative neck for malignant lymph nodes, the planned dissection could be converted to a wait-and-scan policy, whereas DWI positive neck would support the decision to perform a neck dissection. PMID:25003115

  11. Minimally Invasive Magnetic Resonance Imaging-Guided Free-Hand Aspiration of Symptomatic Nerve Route Compressing Lumbosacral Cysts Using a 1.0-Tesla Open Magnetic Resonance Imaging System

    SciTech Connect

    Bucourt, Maximilian de Streitparth, Florian Collettini, Federico; Guettler, Felix; Rathke, Hendrik; Lorenz, Britta; Rump, Jens; Hamm, Bernd; Teichgraeber, U. K.

    2012-02-15

    Purpose: To evaluate the feasibility of minimally invasive magnetic resonance imaging (MRI)-guided free-hand aspiration of symptomatic nerve route compressing lumbosacral cysts in a 1.0-Tesla (T) open MRI system using a tailored interactive sequence. Materials and Methods: Eleven patients with MRI-evident symptomatic cysts in the lumbosacral region and possible nerve route compressing character were referred to a 1.0-T open MRI system. For MRI interventional cyst aspiration, an interactive sequence was used, allowing for near real-time position validation of the needle in any desired three-dimensional plane. Results: Seven of 11 cysts in the lumbosacral region were successfully aspirated (average 10.1 mm [SD {+-} 1.9]). After successful cyst aspiration, each patient reported speedy relief of initial symptoms. Average cyst size was 9.6 mm ({+-}2.6 mm). Four cysts (8.8 {+-} 3.8 mm) could not be aspirated. Conclusion: Open MRI systems with tailored interactive sequences have great potential for cyst aspiration in the lumbosacral region. The authors perceive major advantages of the MR-guided cyst aspiration in its minimally invasive character compared to direct and open surgical options along with consecutive less trauma, less stress, and also less side-effects for the patient.

  12. Tumor Volume Changes on 1.5 Tesla Endorectal MRI During Neoadjuvant Androgen Suppression Therapy for Higher-Risk Prostate Cancer and Recurrence in Men Treated Using Radiation Therapy Results of the Phase II CALGB 9682 Study

    SciTech Connect

    D'Amico, Anthony V. Halabi, Susan; Tempany, Clare; Titelbaum, David; Philips, George K.; Loffredo, Marian; McMahon, Elizabeth; Sanford, Ben; Vogelzang, Nicholas J.; Small, Eric J.

    2008-05-01

    Purpose: We prospectively determined whether the change in tumor volume (TV) during 2 months of neoadjuvant androgen suppression therapy (nAST) measured using conventional 1.5 Tesla endorectal magnetic resonance imaging (eMRI) was associated with the risk of recurrence after radiation (RT) and 6 months of AST. Patients and Methods: Between 1997 and 2001, 180 men with clinical stage T1c-T3cN0M0 adenocarcinoma of the prostate were registered. Fifteen were found to be ineligible and the institutional MR radiologist could not assess the TV in 32, leaving 133 for analysis. Multivariable Cox regression analysis was used to assess whether a significant association existed between eMRI-defined TV progression during nAST and time to recurrence adjusting for prostate-specific antigen (PSA) level, Gleason score (8 to 10 or 7 vs. 6 or less) and stage (T3 vs. T1-2). Results: After a median follow up of 6.7 years and adjusting for known prognostic factors, there was a significant increase in the risk of PSA failure (HR, 2.3 [95% CI, 1.1-4.5; p = 0.025) in men with eMRI-defined TV progression during nAST. Specifically, adjusted estimates of PSA failure were significantly higher (p = 0.032) in men with, compared with men without, eMRI-defined TV progression reaching 38% vs. 19%, respectively, by 5 years. Conclusion: Eradicating intraprostatic hormone refractory prostate cancer (HRPC) by maximizing local control and randomized trials assessing whether survival is improved when agents active against HRPC are combined with maximal local therapy are needed in men who progress based on eMRI during nAST.

  13. Non-contrast-enhanced hepatic MR arteriography with balanced steady-state free-precession and time spatial labeling inversion pulse: optimization of the inversion time at 3 Tesla

    PubMed Central

    Kawahara, Seiya; Ohno, Tsuyoshi; Furuta, Akihiro; Togashi, Kaori

    2015-01-01

    Background A 3 Tesla (3 T) magnetic resonance (MR) scanner is a promising tool for upper abdominal angiography. However, no report has focused on the contrast behavior of non-contrast-enhanced hepatic MR arteriography at 3 T. Purpose To establish the optimal inversion time (TI) for favorable selective visualization of the hepatic arteries on non-contrast-enhanced MR arteriography with time spatial labeling inversion pulse (Time-SLIP) at 3 T. Material and Methods Twenty-five healthy volunteers were examined using respiratory-triggered three-dimensional balanced steady-state free-precession combined with Time-SLIP. According to the difference in the TI, five image groups (A, B, C, D, and E, from 1200 to 2000 ms, increasing at 200-ms intervals) were performed and compared to detect the optimal TI for hepatic artery visualization. The relative Cv-l (vessel-to-liver contrast) was quantified. For qualitative evaluation, the vessel visualization quality and order of the depicted hepatic artery branches were evaluated. Results In group C (TI of 1600 ms), the Cv-l showed the highest probably due to a favorable balance between the hepatic vessel signal and signal recovery of the surrounding tissue. Regarding qualitative assessment, in group C, the mean image quality score of all hepatic arteries and mean maximal visible order of the hepatic artery branches were the highest. However, there was no significant difference between these results. Conclusion Non-contrast-enhanced hepatic MR arteriography with Time-SLIP at 3 T enabled the selective visualization of hepatic arteries at a TI of 1600 ms with an optimal balance between Cv-l and peripheral hepatic artery visualization. PMID:26668756

  14. Biomechanical factors and physical examination findings in osteoarthritis of the knee: associations with tissue abnormalities assessed by conventional radiography and high-resolution 3.0 Tesla magnetic resonance imaging

    PubMed Central

    2012-01-01

    Introduction We aimed to explore the associations between knee osteoarthritis (OA)-related tissue abnormalities assessed by conventional radiography (CR) and by high-resolution 3.0 Tesla magnetic resonance imaging (MRI), as well as biomechanical factors and findings from physical examination in patients with knee OA. Methods This was an explorative cross-sectional study of 105 patients with knee OA. Index knees were imaged using CR and MRI. Multiple features from CR and MRI (cartilage, osteophytes, bone marrow lesions, effusion and synovitis) were related to biomechanical factors (quadriceps and hamstrings muscle strength, proprioceptive accuracy and varus-valgus laxity) and physical examination findings (bony tenderness, crepitus, bony enlargement and palpable warmth), using multivariable regression analyses. Results Quadriceps weakness was associated with cartilage integrity, effusion, synovitis (all detected by MRI) and CR-detected joint space narrowing. Knee joint laxity was associated with MRI-detected cartilage integrity, CR-detected joint space narrowing and osteophyte formation. Multiple tissue abnormalities including cartilage integrity, osteophytes and effusion, but only those detected by MRI, were found to be associated with physical examination findings such as crepitus. Conclusion We observed clinically relevant findings, including a significant association between quadriceps weakness and both effusion and synovitis, detected by MRI. Inflammation was detected in over one-third of the participants, emphasizing the inflammatory component of OA and a possible important role for anti-inflammatory therapies in knee OA. In general, OA-related tissue abnormalities of the knee, even those detected by MRI, were found to be discordant with biomechanical and physical examination features. PMID:23039323

  15. Quantitative comparison of functional contrast from BOLD-weighted spin-echo and gradient-echo echoplanar imaging at 1.5 Tesla and H2 15O PET in the whole brain.

    PubMed

    Lowe, M J; Lurito, J T; Mathews, V P; Phillips, M D; Hutchins, G D

    2000-09-01

    Spin-echo and gradient-echo echoplanar functional magnetic resonance imaging (fMRI) studies at 1.5 Tesla (T) were used to obtain blood oxygenation level-dependent (BOLD) contrast images of the whole brain in seven strongly right-handed women during execution of a complex motor task. Five subjects underwent subsequent H215O positron emission tomography (PET) studies while performing the same task. Group-averaged results for changes in the MRI relaxation rates R2* and R2 at 1.5T in response to neuronal activation in nine cortical, subcortical, and cerebellar motor regions are reported. Results for each method are grouped according to tissue type-cerebral cortex (precentral gyrus and supplementary motor area), subcortical regions (thalamus and putamen), and cerebellar cortex (superior lobule). The observed changes in R2* from activation-induced oxygenation changes were more variable across brain regions with different tissue characteristics than observed changes in R2. The ratio of deltaR2* to deltaR2 was 3.3 +/- 0.9 for cerebral cortex and 2.0 +/- 0.6 for subcortical tissue. deltaR2*, deltaR2, and relative blood flow changes were deltaR2* = -0.201 +/- 0.040 (s-1), deltaR2 = -0.064 +/- 0.011 s(-1), and deltaf/f = 16.7 +/- 0.8% in the cerebral cortex; deltaR2* = -0.100 +/- 0.026 s(-1), deltaR2 = -0.049 +/- 0.009 s(-1), and deltaf/f = 9.4 +/- 0.7% in the subcortical regions; and deltaR2* = -0.215 +/- 0.093 s(-1), deltaR2 = -0.069 +/- 0.012 s(-1), and deltaf/f = 16.2 +/- 1.2% in the cerebellar cortex.

  16. Racial differences in biochemical knee cartilage composition between African-American and Caucasian-American women with 3Tesla MR-based T2 relaxation time measurements – Data from the Osteoarthritis Initiative

    PubMed Central

    YU, A.; Heilmeier, U.; Kretzschmar, M.; Joseph, G.B.; Liu, F.; Liebl, H.; McCulloch, C.E.; Nevitt, M.C.; Lane, Nancy E.; Link, T.M.

    2015-01-01

    Objective To determine whether knee cartilage composition differs between African-American and Caucasian-American women at risk for Osteoarthritis using in-vivo 3 Tesla MRI T2 relaxation time measurements. Methods Right knee MRI studies of 200 subjects (100 African-American women, and 100 closely matched Caucasian-American women) were selected from the Osteoarthritis Initiative. Knee cartilage was segmented in the patellar (PAT), medial and lateral femoral (MF/LF), and medial and lateral tibial compartments (MT/LT)). Mean T2 relaxation time values per compartment and per whole joint cartilage were generated and analyzed spatially via laminar and grey-level co-occurrence matrix texture methods. Presence and severity of cartilage lesions per compartment were graded using a modified WORMS grading. Statistical analysis employed paired t- and McNemar testing. Results While African-American women and Caucasian-Americans had similar WORMS cartilage lesion scores (p=0.970), African-Americans showed significantly lower mean T2 values (~1ms difference; ~0.5SD) than Caucasian-Americans in the whole knee cartilage (p<0.001), and in the subcompartments (LF: p=0.001, MF: p<0.001, LT: p=0.019, MT: p=0.001) and particularly in the superficial cartilage layer (whole cartilage: p<0.001, LF: p<0.001, MF: p<0.001, LT: p=0.003, MT: p<0.001). T2 texture parameters were also significantly lower in the whole joint cartilage of African-Americans than in Caucasian-Americans (variance: p=0.001; contrast: p=0.018). In analyses limited to matched pairs with no cartilage lesions in a given compartment, T2 values remained significantly lower in African-Americans. Conclusion Using T2 relaxation time as a biomarker for the cartilage collagen network, our findings suggest racial differences in the biochemical knee cartilage composition between African-American and Caucasian-American women. PMID:25937026

  17. The Interventional Loopless Antenna at 7 Tesla

    PubMed Central

    Ertürk, Mehmet Arcan; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.

    2012-01-01

    The loopless antenna MRI detector is comprised of a tuned coaxial cable with an extended central conductor that can be fabricated at sub-millimeter diameters for inteventional use in guidewires, catheters or needles. Prior work up to 4.7T suggests a near-quadratic gain in signal-to-noise ratio (SNR) with field strength, and safe operation at 3T. Here for the first time, the SNR performance and RF safety of the loopless antenna is investigated both theoretically, using the electro-magnetic method-of-moments, and experimentally in a standard 7T human scanner. The results are compared with equivalent 3T devices. An absolute SNR gain of 5.7±1.5-fold was realized at 7T vs. 3T: more than 20-fold higher than at 1.5T. The effective field-of-view (FOV) area also increased approximately 10-fold compared to 3T. Testing in a saline gel phantom suggested safe operation is possible with maximum local 1-g average specific absorption rates of <12W/kg and temperature increases of <1.9°C, normalized to a 4W/kg RF field exposure at 7T. The antenna did not affect the power applied to the scanner's transmit coil. The SNR gain enabled MRI microscopy at 40-50μm resolution in diseased human arterial specimens, offering the potential of high-resolution large-FOV or endoscopic MRI for targeted intervention in focal disease. PMID:22161992

  18. Hydroforming of Tesla Cavities at Desy

    SciTech Connect

    W. Singer; H. Kaiser; X. Singer; I. Gonin; I. Zhelezov; T. Khabibullin; P. Kneisel; K. Saito

    2000-07-01

    Since several years the development of seamless niobium cavity fabrication by hydro forming is being pursued at DESY. This technique offers the possibility of lower cost of fabrication and perhaps better rf performance of the cavities because of the elimination of electron-beam welds, which in the standard fabrication technique have sometimes lead to inferior cavity performance due to defects. Several single cell 1300 MHz cavities have been formed from high purity seamless niobium tubes, which are under computer control expanded with internal pressure while simultaneously being swaged axially. The seamless tubes have been made by either back extrusion and flow forming or by spinning or deep drawing. Standard surface treatment techniques such as high temperature post purification, buffered chemical polishing (BCP), electropolishing (EP) and high pressure ultra pure water rinsing (HPR) have been applied to these cavities. The cavities exhibited high Q - values of 2 x 10{sup 10} at 2K and residual resistances as low as 3 n{Omega} after the removal of a surface layer of app. 100 {micro}m by BCP. Surprisingly, even at high gradients up to the maximum measured values of E{sub acc} {approx} 33 MV/m the Q-value did not decrease in the absence of field emission as often observed. After electropolishing of additional 100 {micro}m one of the cavities reached an accelerating gradient of E{sub acc} {ge} 42 MV/m.

  19. 3-Tesla MRI Response to TACE in HCC (Liver Cancer)

    ClinicalTrials.gov

    2016-08-22

    Adult Primary Hepatocellular Carcinoma; Advanced Adult Primary Liver Cancer; Localized Resectable Adult Primary Liver Cancer; Localized Unresectable Adult Primary Liver Cancer; Stage A Adult Primary Liver Cancer (BCLC); Stage B Adult Primary Liver Cancer (BCLC)

  20. Functional magnetic resonance imaging at 0.2 Tesla.

    PubMed

    Stroman, P W; Malisza, K L; Onu, M

    2003-10-01

    Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.2 T, using proton-density weighted (TE = 24 ms) spin-echo imaging, in order to eliminate any contribution from the blood oxygenation-level dependent (BOLD) effect. The purpose of the study was to verify the existence of a proton-density change contribution to spin-echo functional magnetic resonance imaging (fMRI) data. Results demonstrated signal intensity changes in motor and sensory areas of the brain during performance of a motor task and cold sensory stimulation of the hand, with signal changes ranging from 1.7 to 2.3%. These values are consistent with 1.9% signal changes observed previously under similar conditions at 3 T. These findings confirm the proton-density change contribution to spin-echo fMRI data and support the theory of signal enhancement by extravascular water protons (SEEP) as a non-BOLD fMRI contrast mechanism. This study also demonstrates that fMRI based on the SEEP contrast mechanism can be carried out at low fields where the BOLD effect is expected to be negligible.

  1. From Tesla to Tetris: Mental Rotation, Vocation, and Gifted Education

    ERIC Educational Resources Information Center

    von Károlyi, Catya

    2013-01-01

    Mental rotation ability is important for success in a number of academic and career fields, especially the science, technology, engineering, and mathematics (STEM) domains. Individual differences in intelligence, spatial ability, strategy selection biases, and gender are all associated with proficiency in mental rotation. Interventions and…

  2. Single Voxel Proton Spectroscopy for Neurofeedback at 7 Tesla.

    PubMed

    Koush, Yury; Elliott, Mark A; Mathiak, Klaus

    2011-09-01

    Echo-planar imaging (EPI) in fMRI is regularly used to reveal BOLD activation in presubscribed regions of interest (ROI). The response is mediated by relative changes in T2* which appear as changes in the image pixel intensities. We have proposed an application of functional single-voxel proton spectroscopy (fSVPS) for real-time studies at ultra-high MR field which can be comparable to the EPI BOLD fMRI technique. A spin-echo SVPS protocol without water suppression was acquired with 310 repetitions on a 7T Siemens MR scanner (TE/TR = 20/1000 ms, flip angle α = 90°, voxel size 10 × 10 × 10 mm(3)). Transmitter reference voltage was optimized for the voxel location. Spectral processing of the water signal free induction decay (FID) using log-linear regression was used to estimate the T2* change between rest and activation of a functional task. The FID spectrum was filtered with a Gaussian window around the water peak, and log-linear regression was optimized for the particular ROI by adoption of the linearization length. The spectroscopic voxel was positioned on an ROI defined from a real-time fMRI EPI BOLD localizer. Additional online signal processing algorithms performed signal drift removal (exponential moving average), despiking and low-pass filtering (modified Kalman filter) and, finally, the dynamic feedback signal normalization. Two functional tasks were used to estimate the sensitivity of the SVPS method compared to BOLD signal changes, namely the primary motor cortex (PMC, left hand finger tapping) and visual cortex (VC, blinking checkerboard). Four healthy volunteers performed these tasks and an additional session using real-time signal feedback modulating their activation level of the PMC. Results show that single voxel spectroscopy is able to provide a good and reliable estimation of the BOLD signal changes. Small data size and FID signal processing instead of processing entire brain volumes as well as more information revealed from the acquired total water spectrum, i.e., direct estimation of the T2* values and B0 changes, make SVPS proton spectroscopy suitable and advantageous for real-time neurofeedback studies. Particular challenges of ultra-high field spectroscopy due to the non-linearity in the spectral information, e.g., poor main magnetic field homogeneity and the absence of motion correction for the SVPS sequence may lead to the special artifacts in the control signal which still need to be addressed. The contrast to noise ratio (CNR), experimental statistic (t-values) and percent signal change were used as quality parameters to estimate the method performance. The potential and challenges of the spectroscopic approach for fMRI studies needs to be further investigated.

  3. Beyond 100 Tesla: Scientific experiments using single-turn coils

    NASA Astrophysics Data System (ADS)

    Portugall, Oliver; Solane, Pierre Yves; Plochocka, Paulina; Maude, Duncan K.; Nicholas, Robin J.

    2013-01-01

    Current opportunities and recent examples for research in magnetic fields well above 100 T using single-turn coils are discussed. After a general introduction into basic principles and technical constraints associated with the generation of Megagauss fields we discuss data obtained at the LNCMI Toulouse, where such fields are routinely used for scientific applications.

  4. 7 Tesla MRI demonstrates vascular pathology in Balo's concentric sclerosis.

    PubMed

    Berghoff, M; Schlamann, M U; Maderwald, S; Grams, A E; Kaps, M; Ladd, M E; Gizewski, E R

    2013-01-01

    Baló's concentric sclerosis (BCS) is an inflammatory demyelinating disease related to multiple sclerosis; its underlying pathology remains unclear. At 7 T MRI in a 19-year-old female BCS patient, microhaemorrhages and ectatic veins were found in T2 hyperintense regions, features which have not been previously reported in conjunction with BCS, and these findings may support the view that vascular pathology plays a role in BCS. MRS data suggest that neuron loss and lipid turnover still took place months after a remission. Plasma exchange was effective in treating a relapse with severe motor deficits, and the off-label use of natalizumab was successful in maintaining remission in this patient.

  5. 6. 4 Tesla dipole magnet for the SSC

    SciTech Connect

    Taylor, C.E.; Caspi, S.; Gilbert, W.; Meuser, R.; Mirk, K.; Peters, C.; Scanlan, R.; Dahl, P.; Cottingham, J.; Hassenzahl, W.

    1985-05-01

    A design is presented for a dipole magnet suitable for the proposed SSC facility. Test results are given for model magnets of this design 1 m long and 4.5 m long. Flattened wedge-shaped cables (''keystoned'') are used in a graded, two-layer ''cos theta'' configuration with three wedges to provide sufficient field uniformity and mechanical rigidity. Stainless steel collars 15 mm wide, fastened with rectangular keys, provide structural support, and there is a ''cold'' iron flux return. The outer-layer cable has 30 strands of 0.0255 in. dia NbTi multifilamentary wire with Cu/S.C. = 1.8, and the inner has 23 strands of .0318 in. dia wire with Cu/S.C. = 1.3. Performance data is given including training behavior, winding stresses, collar deformation, and field uniformity.

  6. High Spatial Resolution Cardiovascular Magnetic Resonance at 7.0 Tesla in Patients with Hypertrophic Cardiomyopathy – First Experiences: Lesson Learned from 7.0 Tesla

    PubMed Central

    Prothmann, Marcel; von Knobelsdorff-Brenkenhoff, Florian; Töpper, Agnieszka; Dieringer, Matthias A.; Shahid, Etham; Graessl, Andreas; Rieger, Jan; Lysiak, Darius; Thalhammer, C.; Huelnhagen, Till; Kellman, Peter; Niendorf, Thoralf; Schulz-Menger, Jeanette

    2016-01-01

    Background Cardiovascular Magnetic Resonance (CMR) provides valuable information in patients with hypertrophic cardiomyopathy (HCM) based on myocardial tissue differentiation and the detection of small morphological details. CMR at 7.0T improves spatial resolution versus today’s clinical protocols. This capability is as yet untapped in HCM patients. We aimed to examine the feasibility of CMR at 7.0T in HCM patients and to demonstrate its capability for the visualization of subtle morphological details. Methods We screened 131 patients with HCM. 13 patients (9 males, 56 ±31 years) and 13 healthy age- and gender-matched subjects (9 males, 55 ±31years) underwent CMR at 7.0T and 3.0T (Siemens, Erlangen, Germany). For the assessment of cardiac function and morphology, 2D CINE imaging was performed (voxel size at 7.0T: (1.4x1.4x2.5) mm3 and (1.4x1.4x4.0) mm3; at 3.0T: (1.8x1.8x6.0) mm3). Late gadolinium enhancement (LGE) was performed at 3.0T for detection of fibrosis. Results All scans were successful and evaluable. At 3.0T, quantification of the left ventricle (LV) showed similar results in short axis view vs. the biplane approach (LVEDV, LVESV, LVMASS, LVEF) (p = 0.286; p = 0.534; p = 0.155; p = 0.131). The LV-parameters obtained at 7.0T where in accordance with the 3.0T data (pLVEDV = 0.110; pLVESV = 0.091; pLVMASS = 0.131; pLVEF = 0.182). LGE was detectable in 12/13 (92%) of the HCM patients. High spatial resolution CINE imaging at 7.0T revealed hyperintense regions, identifying myocardial crypts in 7/13 (54%) of the HCM patients. All crypts were located in the LGE-positive regions. The crypts were not detectable at 3.0T using a clinical protocol. Conclusions CMR at 7.0T is feasible in patients with HCM. High spatial resolution gradient echo 2D CINE imaging at 7.0T allowed the detection of subtle morphological details in regions of extended hypertrophy and LGE. PMID:26863618

  7. Composite RF pulses for B1+-insensitive volume excitation at 7 Tesla

    PubMed Central

    Moore, Jay; Jankiewicz, Marcin; Zeng, Huairen; Anderson, Adam W.; Gore, John C.

    2010-01-01

    A new class of composite RF pulses that perform well in the presence of specific ranges of B0 and B1+ inhomogeneities has been designed for volume (non-selective) excitation in MRI. The pulses consist of numerous (~ 100) short (~ 10µs) block-shaped sub-pulses each with different phases and amplitudes derived from numerical optimization. Optimized pulses are designed to be effective over a specific range of frequency offsets and transmit field variations and are thus implementable regardless of field strength, transmit coil configuration, or the subject-specific spatial distribution of the static and RF fields. In the context of 7T human brain imaging, both simulations and phantom experiments indicate that optimized pulses result in similar on-resonance flip-angle uniformity as BIR-4 pulses but with the advantages of superior off-resonance stability and significantly reduced average power. The pulse design techniques presented here are thus well-suited for practical application in ultra-high field human MRI. PMID:20451430

  8. High-Resolution MR Imaging of the Human Brainstem In vivo at 7 Tesla

    PubMed Central

    Deistung, Andreas; Schäfer, Andreas; Schweser, Ferdinand; Biedermann, Uta; Güllmar, Daniel; Trampel, Robert; Turner, Robert; Reichenbach, Jürgen R.

    2013-01-01

    The human brainstem, which comprises a multitude of axonal nerve fibers and nuclei, plays an important functional role in the human brain. Depicting its anatomy non-invasively with high spatial resolution may thus in turn help to better relate normal and pathological anatomical variations to medical conditions as well as neurological and peripheral functions. We explored the potential of high-resolution magnetic resonance imaging (MRI) at 7 T for depicting the intricate anatomy of the human brainstem in vivo by acquiring and generating images with multiple contrasts: T2-weighted images, quantitative maps of longitudinal relaxation rate (R1 maps) and effective transverse relaxation rate (R2* maps), magnetic susceptibility maps, and direction-encoded track-density images. Images and quantitative maps were compared with histological stains and anatomical atlases to identify nerve nuclei and nerve fibers. Among the investigated contrasts, susceptibility maps displayed the largest number of brainstem structures. Contrary to R1 maps and T2-weighted images, which showed rather homogeneous contrast, R2* maps, magnetic susceptibility maps, and track-density images clearly displayed a multitude of smaller and larger fiber bundles. Several brainstem nuclei were identifiable in sections covering the pons and medulla oblongata, including the spinal trigeminal nucleus and the reticulotegmental nucleus on magnetic susceptibility maps as well as the inferior olive on R1, R2*, and susceptibility maps. The substantia nigra and red nuclei were visible in all contrasts. In conclusion, high-resolution, multi-contrast MR imaging at 7 T is a versatile tool to non-invasively assess the individual anatomy and tissue composition of the human brainstem. PMID:24194710

  9. Conceptual design of a 2 tesla superconducting solenoid for the Fermilab D{O} detector upgrade

    SciTech Connect

    Brzezniak, J.; Fast, R.W.; Krempetz, K.

    1994-05-01

    This paper presents a conceptual design of a superconducting solenoid to be part of a proposed upgrade for the D0 detector. This detector was completed in 1992, and has been taking data since then. The Fermilab Tevatron had scheduled a series of luminosity enhancements prior to the startup of this detector. In response to this accelerator upgrade, efforts have been underway to design upgrades for D0 to take advantage of the new luminosity, and improvements in detector technology. This magnet is conceived as part of the new central tracking system for D0, providing a radiation-hard high-precision magnetic tracking system with excellent electron identification.

  10. Multi-cavity complex controller with vector simulator for TESLA technology linear accelerator

    NASA Astrophysics Data System (ADS)

    Czarski, Tomasz; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Szewinski, Jaroslaw

    2008-01-01

    A digital control, as the main part of the Low Level RF system, for superconducting cavities of a linear accelerator is presented. The FPGA based controller, supported by MATLAB system, was developed to investigate a novel firmware implementation. The complex control algorithm based on the non-linear system identification is the proposal verified by the preliminary experimental results. The general idea is implemented as the Multi-Cavity Complex Controller (MCC) and is still under development. The FPGA based controller executes procedure according to the prearranged control tables: Feed-Forward, Set-Point and Corrector unit, to fulfill the required cavity performance: driving in the resonance during filling and field stabilization for the flattop range. Adaptive control algorithm is applied for the feed-forward and feedback modes. The vector Simulator table has been introduced for an efficient verification of the FPGA controller structure. Experimental results of the internal simulation, are presented for a cavity representative condition.

  11. An additive manufacturing acrylic for use in the 32 Tesla all superconducting magnet

    NASA Astrophysics Data System (ADS)

    Johnson, Zachary

    The National High Magnetic Field Laboratory is building a world record all superconducting magnet known as the "32T". It requires many thousands of parts, but in particular one kind is unusually expensive to manufacture, called "heater lead covers". These parts are traditionally made out of a glass filled epoxy known as G-10, and conventionally machined. The machining is the expensive portion, as there are many tight tolerance details. The proposal in this paper is to change the material and manufacturing method to additive manufacturing with the material called "RGD 430". The cost per part with traditional machining is approximately 1,500 each. The cost per part with additive manufacturing of RGD 430 is approximately 32.5 each. There will be at least 14 of this style of part on the completed 32T project. Thus the total cost for the project will be reduced from 21,000 to 455, a 98% cost savings. The additive manufacturing also allows the machine designers to expand the dimensions of the part to any shape possible. Through testing of the material it was found to follow the common polymer characteristics. Its linear elastic modulus at cryogenic temperatures approached 10 GPa. The yield strength was always over 100 MPa, when not damaged. The fracture mechanism was repeatable, and brittle in cryogenic environments. The geometric tolerancing of the additive manufacturing process are, as expected extremely precise. The final tolerances for dimensions in the profile of the printer are more precise than +/- 0.10mm. The final tolerances for dimensions in the thickness of the printer are more precise than +/-0.25mm. Before utilizing the material, there should be a few additional tests run on it to ensure it will work in-situ. Those tests are outside the scope of this thesis.

  12. Retrieval, Monitoring, and Control Processes: A 7 Tesla fMRI Approach to Memory Accuracy

    PubMed Central

    Risius, Uda-Mareke; Staniloiu, Angelica; Piefke, Martina; Maderwald, Stefan; Schulte, Frank P.; Brand, Matthias; Markowitsch, Hans J.

    2012-01-01

    Memory research has been guided by two powerful metaphors: the storehouse (computer) and the correspondence metaphor. The latter emphasizes the dependability of retrieved mnemonic information and draws upon ideas about the state dependency and reconstructive character of episodic memory. We used a new movie to unveil the neural correlates connected with retrieval, monitoring, and control processes, and memory accuracy (MAC), according to the paradigm of Koriat and Goldsmith (1996a,b). During functional magnetic resonance imaging, subjects performed a memory task which required (after an initial learning phase) rating true and false statements [retrieval phase (RP)], making confidence judgments in the respective statement [monitoring phase (MP)], and deciding for either venturing (volunteering) the respective answer or withholding the response [control phase (CP)]. Imaging data pointed to common and unique neural correlates. Activations in brain regions related to RP and MAC were observed in the precuneus, middle temporal gyrus, and left hippocampus. MP was associated with activation in the left anterior and posterior cingulate cortex along with bilateral medial temporal regions. If an answer was volunteered (as opposed to being withheld) during the CP, temporal, and frontal as well as middle and posterior cingulate areas and the precuneus revealed activations. Increased bilateral hippocampal activity was found during withholding compared to volunteering answers. The left caudate activation detected during withholding compared to venturing an answer supports the involvement of the left caudate in inhibiting unwanted responses. Contrary to expectations, we did not evidence prefrontal activations during withholding (as opposed to volunteering) answers. This may reflect our design specifications, but alternative interpretations are put forth. PMID:23580061

  13. Gain length dependence on phase shake in the VUV-FEL at the TESLA Test Facility

    SciTech Connect

    Pflueger, J.; Pierini, P.

    1995-12-31

    The TTF VUV FEL, which is in its design stage at DESY, consists of a 30 m long SASE FEL which will radiate around 6 nm, driven by a superconducting linac with final energy of 1 GeV. One of the important issues in its design is the undulator performance, which is studied in this paper. The present setup, including FODO lattice, is discussed in this paper. Results of simulations, including the realistic wiggler field errors and beam stearing, are presented. Dependence of the performance, in particular the gain and saturation length as well as the saturation peak power, on the wiggler field errors is discussed.

  14. Automated tuning of an eight-channel cardiac transceive array at 7 tesla using piezoelectric actuators

    PubMed Central

    Keith, Graeme A; Rodgers, Christopher T; Hess, Aaron T; Snyder, Carl J; Vaughan, J Thomas; Robson, Matthew D

    2015-01-01

    Purpose Ultra-high field (UHF) MR scanning in the body requires novel coil designs due to B1 field inhomogeneities. In the transverse electromagnetic field (TEM) design, maximum B1 transmit power can only be achieved if each individual transmit element is tuned and matched for different coil loads, which requires a considerable amount of valuable scanner time. Methods An integrated system for autotuning a multichannel parallel transmit (pTx) cardiac TEM array was devised, using piezoelectric actuators, power monitoring equipment and control software. The reproducibility and performance of the system were tested and the power responses of the coil elements were profiled. An automated optimization method was devised and evaluated. Results The time required to tune an eight-element pTx cardiac RF array was reduced from a mean of 30 min to less than 10 min with the use of this system. Conclusion Piezoelectric actuators are an attractive means of tuning RF coil arrays to yield more efficient B1 transmission into the subject. An automated mechanism for tuning these elements provides a practical solution for cardiac imaging at UHF, bringing this technology closer to clinical use. Magn Reson Med 73:2390–2397, 2015. © 2014 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. PMID:24986525

  15. High resolution neurography of the brachial plexus by 3 Tesla magnetic resonance imaging.

    PubMed

    Cejas, C; Rollán, C; Michelin, G; Nogués, M

    2016-01-01

    The study of the structures that make up the brachial plexus has benefited particularly from the high resolution images provided by 3T magnetic resonance scanners. The brachial plexus can have mononeuropathies or polyneuropathies. The mononeuropathies include traumatic injuries and trapping, such as occurs in thoracic outlet syndrome due to cervical ribs, prominent transverse apophyses, or tumors. The polyneuropathies include inflammatory processes, in particular chronic inflammatory demyelinating polyneuropathy, Parsonage-Turner syndrome, granulomatous diseases, and radiation neuropathy. Vascular processes affecting the brachial plexus include diabetic polyneuropathy and the vasculitides. This article reviews the anatomy of the brachial plexus and describes the technique for magnetic resonance neurography and the most common pathologic conditions that can affect the brachial plexus. PMID:26860655

  16. In vivo localized 1H NMR spectroscopy at 11.7 Tesla

    NASA Astrophysics Data System (ADS)

    Crozier, Stuart; Field, James; Brereton, Ian M.; Moxon, Leith N.; Shannon, Gerald F.; Doddrell, David M.

    The SPACE volume-selection technique has been used to acquire high-resolution 1H spectra from the brain of neonate mice at 11.7 T (500 MHz). Spectra were acquired from voxels smaller than 20 μl. The spectra display elevated intensities of resonances arising from taurine and reduced intensities of those arising from N-acetylaspartate, when compared to those of mature animals, correlating well with in vitro studies. An integrated probe design consisting of separate transmission and reception RF coils and linear gradient coils is described. Comments are made concerning the advantages and disadvantages of performing gradient-encoded localized spectroscopy at this field strength.

  17. Opportunities and Challenges of 7 Tesla Magnetic Resonance Imaging: A Review.

    PubMed

    Karamat, Muhammad Irfan; Darvish-Molla, Sahar; Santos-Diaz, Alejandro

    2016-01-01

    The desire to achieve clinical ultra-high magnetic resonance imaging (MRI) systems stems from the fact that higher field strength leads to higher signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and spatial resolution. During last few years 7T MRI systems have become a quasi standard for ultra-high field MRI (UhFMRI) systems. This review presents a detailed account of opportunities and challenges associated with a clinical 7T MRI system for cranial and extracranial imaging. As with all of the previous transitions to higher field strengths, the switch from high to UhFMRI is not easy. The engineering and scientific community have to overcome challenges like magnetic field inhomogeneity, patient safety and comfort issues, and cost and related problems in order to achieve a clinically viable UhFMRI system. In addition, a large number of clinical studies are still required to show the improvements in quality of diagnostics that would come with 7T MRI, in order to bring such a research tool to the clinic. PMID:27652452

  18. Multiparametric 3-Tesla Endorectal MR Imaging after External Beam Radiation Therapy of Prostate Cancer

    PubMed Central

    Westphalen, Antonio C.; Reed, Galen D.; Vinh, Phillip P.; Sotto, Christopher; Vigneron, Daniel B.; Kurhanewicz, John

    2012-01-01

    Purpose To determine the best combination of magnetic resonance (MR) imaging parameters for the detection of locally recurrent prostate cancer after external beam radiation therapy. Materials and Methods Our IRB approved this study with a waiver of informed consent. Twenty-six patients with suspected recurrence due to biochemical failure were part of this research. The MR protocol included T2-weighted, MR spectroscopic, and diffusion-weighted MR imaging. Transrectal ultrasound-guided biopsy was the standard of reference. We used logistic regression to model the probability of a positive outcome and generalized estimating equations to account for clustering. The diagnostic performance of imaging was described using receiver operating characteristic (ROC) curves. Results The area under the ROC curve of MR spectroscopic imaging (MRSI) was 83.0% (95% CI = 75.5 to 89.1). The combination of all MR techniques did not significantly improve the performance of imaging beyond the accuracy of MRSI alone, but a trend towards improved discrimination was noted (86.9%; 95% CI = 77.6 to 93.4; P = 0.09). Conclusion In conclusion, incorporation of MRSI to T2-weighted and/or diffusion-weighted MR imaging significantly improves the assessment of patients with suspected recurrence after radiotherapy and a combined approach with all three modalities may have the best diagnostic performance. PMID:22535708

  19. Novel finding of optic nerve central T2 hypointensity utilizing 3 Tesla MR imaging.

    PubMed

    Riascos, Roy; Heymann, John C; Hakimelahi, Reza; Hasan, Khader; Sargsyan, Ashot; Barr, Yael R; Tom, James; Alperin, Noam; Kramer, Larry A

    2015-04-01

    We sought to report a central T2 hypointensity within the optic nerve on 3 T MRI studies obtained as part of the NASA Flight Medicine Visual Impairment Intracranial Pressure Protocol that had not been described previously. Twenty-one astronauts, who had undergone MRI of both orbits with direct coronal T2 sequences between 2010 and 2012, were retrospectively included. Two of the astronauts did not have previous exposure to microgravity at the time of their scans. A central T2 hypointensity was observed in 100% of both right and left eyes. It was completely visualized throughout the nerve course in 15 right eyes (71.4%) and in 19 left eyes (90.5%).We describe a new finding seen in all study participants: a central T2 hypointensity in the epicenter of the optic nerve. We speculate that this T2 hypointensity may represent flow voids caused by the central retinal vessels.

  20. High resolution neurography of the brachial plexus by 3 Tesla magnetic resonance imaging.

    PubMed

    Cejas, C; Rollán, C; Michelin, G; Nogués, M

    2016-01-01

    The study of the structures that make up the brachial plexus has benefited particularly from the high resolution images provided by 3T magnetic resonance scanners. The brachial plexus can have mononeuropathies or polyneuropathies. The mononeuropathies include traumatic injuries and trapping, such as occurs in thoracic outlet syndrome due to cervical ribs, prominent transverse apophyses, or tumors. The polyneuropathies include inflammatory processes, in particular chronic inflammatory demyelinating polyneuropathy, Parsonage-Turner syndrome, granulomatous diseases, and radiation neuropathy. Vascular processes affecting the brachial plexus include diabetic polyneuropathy and the vasculitides. This article reviews the anatomy of the brachial plexus and describes the technique for magnetic resonance neurography and the most common pathologic conditions that can affect the brachial plexus.

  1. Tracking Iron in Multiple Sclerosis: A Combined Imaging and Histopathological Study at 7 Tesla

    ERIC Educational Resources Information Center

    Bagnato, Francesca; Hametner, Simon; Yao, Bing; van Gelderen, Peter; Merkle, Hellmut; Cantor, Fredric K.; Lassmann, Hans; Duyn, Jeff H.

    2011-01-01

    Previous authors have shown that the transverse relaxivity R[subscript 2][superscript *] and frequency shifts that characterize gradient echo signal decay in magnetic resonance imaging are closely associated with the distribution of iron and myelin in the brain's white matter. In multiple sclerosis, iron accumulation in brain tissue may reflect a…

  2. 77 FR 22383 - Petition for Exemption From the Federal Motor Vehicle Motor Theft Prevention Standard; TESLA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-13

    ... Mercedes-Benz E-Class to its Model S vehicle line. Specifically, the agency's data show that theft rates for the BMW 5 series are 0.9044, 0.6550 and 0.4098 and for the Mercedes- Benz E-Class, 0.5898, 0.6286... that the average theft rate for the BMW 5 series is 0.6564 and 0.7075 for the Mercedes-Benz...

  3. Simulation Study on Active Noise Control for a 4 Tesla MRI Scanner

    PubMed Central

    Li, Mingfeng; Lim, Teik C.; Lee, Jing-Huei

    2008-01-01

    The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for MRI acoustic noise reduction. A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study. By comparing three different control systems, namely the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20 dB reduction at the principal frequency component. We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction. PMID:18060719

  4. In Situ Active Control of Noise in a 4-Tesla MRI Scanner

    PubMed Central

    Li, Mingfeng; Rudd, Brent; Lim, Teik C.; Lee, Jing-Huei

    2011-01-01

    Purpose To evaluate the effectiveness of the proposed active noise control (ANC) system for the reduction of the acoustic noise emission generated by a 4 T MRI scanner during operation and to assess the feasibility of developing an ANC device that can be deployed in situ. Materials and Methods Three typical scanning sequences, namely EPI (echo planar imaging), GEMS (gradient echo multi-slice) and MDEFT (Modified Driven Equilibrium Fourier Transform), were used for evaluating the performance of the ANC system, which was composed of a magnetic compatible headset and a multiple reference feedforward filtered-x least mean square controller. Results The greatest reduction, about 55 dB, was achieved at the harmonic at a frequency of 1.3 kHz in the GEMS case. Approximately 21 dB and 30 dBA overall reduction was achieved for GEMS noise across the entire audible frequency range. For the MDEFT sequence, the control system achieved 14 dB and 14 dBA overall reduction in the audible frequency range, while 13 dB and 14 dBA reduction was obtained for the EPI case. Conclusion The result is highly encouraging because it shows great potential for treating MRI noise with an ANC application during real time scanning. PMID:21751284

  5. Detailing Radio Frequency Heating Induced by Coronary Stents: A 7.0 Tesla Magnetic Resonance Study

    PubMed Central

    Santoro, Davide; Winter, Lukas; Müller, Alexander; Vogt, Julia; Renz, Wolfgang; Özerdem, Celal; Grässl, Andreas; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2012-01-01

    The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR) holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF) power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF) simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR) limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study. PMID:23185498

  6. Commissioning report of the MuCool 5 Tesla solenoid coupled with helium refrigerator

    SciTech Connect

    Geynisman, Michael; /Fermilab

    2010-05-01

    MuCool 5T solenoid was successfully cooled down and operated coupled with MTA 'Brown' refrigerator. The system performed as designed with substantial performance margin. All process alarms and interlocks, as well as ODH and fire alarms, were active and performed as designed. The cooldown of the refrigerator started from warm conditions and took 44 hours to accumulate liquid helium level and solenoid temperature below 5K. Average liquid nitrogen consumption for the refrigerator precool and solenoid shield was measured as 20 gal/hr (including boil-off). Helium losses were small (below 30 scfh). The system was stable and with sufficient margin of performance and ran stably without wet expansion engine. Quench response demonstrated proper operation of the relieving devices and pointed to necessity of improving tightness of the relieving manifolds. Boil-off test demonstrated average heat load of 3 Watts for the unpowered solenoid. The solenoid can stay up to 48 hours cold and minimally filled if the nitrogen shield is maintained. A list of improvements includes commencing into operations the second helium compressor and completion of improvements and tune-ups for system efficiency.

  7. Test of a 1.8 Tesla, 400 Hz Dipole for a Muon Synchrotron

    SciTech Connect

    Summers, D.J.; Cremaldi, L.M.; Hart, T.L.; Perera, L.P.; Reep, M.; Witte, H.; Hansen, S.; Lopes, M.L.; Reidy Jr., J.; /Oxford High School

    2012-05-01

    A 1.8 T dipole magnet using thin grain oriented silicon steel laminations has been constructed as a prototype for a muon synchrotron ramping at 400 Hz. Following the practice in large 3 phase transformers and our own Opera-2d simulations, joints are mitred to take advantage of the magnetic properties of the steel which are much better in the direction in which the steel was rolled. Measurements with a Hysteresigraph 5500 and Epstein frame show a high magnetic permeability which minimizes stored energy in the yoke allowing the magnet to ramp quickly with modest voltage. Coercivity is low which minimizes hysteresis losses. A power supply with a fast Insulated Gate Bipolar Transistor (IGBT) switch and a capacitor was constructed. Coils are wound with 12 gauge copper wire. Thin wire and laminations minimize eddy current losses. The magnetic field was measured with a peak sensing Hall probe.

  8. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zhu, Yue; Chen, Chia-Hsiu; Wilson, Zechariah; Savukov, Igor; Hilty, Christian

    2016-09-01

    Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7 mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from 1H and 19F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

  9. Composite RF pulses for B1+-insensitive volume excitation at 7 Tesla

    NASA Astrophysics Data System (ADS)

    Moore, Jay; Jankiewicz, Marcin; Zeng, Huairen; Anderson, Adam W.; Gore, John C.

    2010-07-01

    A new class of composite RF pulses that perform well in the presence of specific ranges of B0 and B1+ inhomogeneities has been designed for volume (non-selective) excitation in MRI. The pulses consist of numerous (˜100) short (˜10 μs) block-shaped sub-pulses each with different phases and amplitudes derived from numerical optimization. Optimized pulses are designed to be effective over a specific range of frequency offsets and transmit field variations and are thus implementable regardless of field strength, transmit coil configuration, or the subject-specific spatial distribution of the static and RF fields. In the context of 7 T human brain imaging, both simulations and phantom experiments indicate that optimized pulses result in similar on-resonance flip-angle uniformity as BIR-4 pulses but with the advantages of superior off-resonance stability and significantly reduced average power. The pulse design techniques presented here are thus well-suited for practical application in ultra-high field human MRI.

  10. 33.8 Tesla with a YBa2Cu3O7-x Superconducting Test Coil

    NASA Astrophysics Data System (ADS)

    Markiewicz, W. D.; Weijers, H. W.; Noyes, P. D.; Trociewitz, U. P.; Pickard, K. W.; Sheppard, W. R.; Jaroszynski, J. J.; Xu, A.; Larbalestier, D. C.; Hazelton, D. W.

    2010-04-01

    A small coil was made and tested for the purpose of magnet technology development for YBa2Cu3O7-x (YBCO) high field coils. The coil has a winding inner diameter of 24 mm, outer diameter of 36 mm, and length of 46 mm in a pancake wound construction of 5 double pancakes. The YBCO conductor is SuperPower SCS4050 with 2×20 μm of copper stabilizer. The coil was tested in the high field user facility of the NHMFL in a 31 T background field magnet. At this background field, the coil was operated to a current of 325 A and produced a field increment of 2.8 T for a record total field of 33.8 T. The average current density in the windings at full current was very high at 446 A/mm2. The test was complicated by the accumulation of trapped helium gas about the coil due to the diamagnetic effect of helium at high field. Even though the coil operated at elevated temperature during the high field test, the coil performance was limited by mechanical degradation and not a critical current limit.

  11. Sultan: an 8 Tesla, 1 meter bore test facility for the outer solenoid

    SciTech Connect

    Pasotti, G.; Ricci, M.V.; Sacchetti, N.; Spadoni, M.

    1981-09-01

    In the framework of the international collaboration among SIN-Villigen (CH), ECN-Patten (NL) and CNEN-Frascati (I) aiming at the realization of the SULTAN (SUpraLeitender TestANlage) test facility the CNEN contribution is concerned with the realization of the outer part of the solenoid, i.e., the section which will provide the 6T field in the useful region, the remaining 2T being supplied by the coaxial ECN insert. A description of the 6T superconducting solenoid is presented. The main features are: (1) pancake structure wound by a Nb-Ti multifilamentary hollow cable; and (2) cooling by forced flow of slightly subcooled liquid helium. Details of the design, winding technique and structure, the hydraulic circuitry as well as the status report of the construction are discussed. 10 refs.

  12. Orientational control of block copolymer microdomains by sub-tesla magnetic fields

    NASA Astrophysics Data System (ADS)

    Gopinadhan, Manesh; Choo, Youngwoo; Feng, Xunda; Kawabata, Kohsuke; di, Xiaojun; Osuji, Chinedum

    Magnetic fields offer a versatile approach to controlling the orientation of block copolymer (BCP) microdomains during self-assembly. To date however, such control has required the imposition of large magnetic fields (>3T), necessitating the use of complex magnet systems - either superconducting or very large conventional resistive magnets. Here we demonstrate the ability to direct BCP self-assembly using considerably smaller fields (<1T) which are accessible using simple rare-earth permanent magnets. The low field alignment is enabled by the presence of small quantities of mesogenic species that are blended into, and co-assemble with the liquid crystalline (LC) mesophase of the side-chain LC BCP under study. In situ SAXS experiments reveal a pronounced dependence of the critical alignment field strength on the stoichiometry of the blend, and the ability to generate aligned microdomains with orientational distribution coefficients exceeding 0.95 at sub-1 T fields for appropriate stoichiometries. The alignment response overall can be rationalized in terms of increased mobility and grain size due to the presence of the mesogenic additive. We use a permanent magnet to fabricate films with aligned nanopores, and the utility of this approach to generate complex BCP microdomain patterns in thin films by local field screening are highlighted. NSF DMR-1410568 and DMR-0847534.

  13. Impact of Gd3+ doping and glassing solvent deuteration on 13C DNP at 5 Tesla

    NASA Astrophysics Data System (ADS)

    Kiswandhi, Andhika; Lama, Bimala; Niedbalski, Peter; Goderya, Mudrekh; Long, Joanna; Lumata, Lloyd

    Dynamic nuclear polarization (DNP) is a technique which can be used to amplify signals in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) by several thousand-fold. The most commonly available DNP system typically operates at the W-band field or 3.35 T, at which it has been shown that 13C NMR signal can be enhanced by deuteration and Gd3+ doping. In this work, we have investigated the applicability of these procedures at 5 T. Our results indicate that the deuteration of the glassing matrix still yields an enhancement of 13C DNP when 4-oxo-TEMPO free radical is used. The effect is attributed to the lower heat load of the deuterons compared to protons. An addition of a trace amount of Gd3+ gives a modest enhancement of the signal when trityl OX063 is used, albeit with a less pronounced relative enhancement compared to the results obtained at 3.35 T. The results suggest that the enhancement obtained via Gd3+ doping may become saturated at higher field. These results will be discussed using a thermodynamic model of DNP. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  14. Novel finding of optic nerve central T2 hypointensity utilizing 3 Tesla MR imaging.

    PubMed

    Riascos, Roy; Heymann, John C; Hakimelahi, Reza; Hasan, Khader; Sargsyan, Ashot; Barr, Yael R; Tom, James; Alperin, Noam; Kramer, Larry A

    2015-04-01

    We sought to report a central T2 hypointensity within the optic nerve on 3 T MRI studies obtained as part of the NASA Flight Medicine Visual Impairment Intracranial Pressure Protocol that had not been described previously. Twenty-one astronauts, who had undergone MRI of both orbits with direct coronal T2 sequences between 2010 and 2012, were retrospectively included. Two of the astronauts did not have previous exposure to microgravity at the time of their scans. A central T2 hypointensity was observed in 100% of both right and left eyes. It was completely visualized throughout the nerve course in 15 right eyes (71.4%) and in 19 left eyes (90.5%).We describe a new finding seen in all study participants: a central T2 hypointensity in the epicenter of the optic nerve. We speculate that this T2 hypointensity may represent flow voids caused by the central retinal vessels. PMID:25923682

  15. Transmit and receive transmission line arrays for 7 Tesla parallel imaging.

    PubMed

    Adriany, Gregor; Van de Moortele, Pierre-Francois; Wiesinger, Florian; Moeller, Steen; Strupp, John P; Andersen, Peter; Snyder, Carl; Zhang, Xiaoliang; Chen, Wei; Pruessmann, Klaas P; Boesiger, Peter; Vaughan, Tommy; Uğurbil, Kāmil

    2005-02-01

    Transceive array coils, capable of RF transmission and independent signal reception, were developed for parallel, 1H imaging applications in the human head at 7 T (300 MHz). The coils combine the advantages of high-frequency properties of transmission lines with classic MR coil design. Because of the short wavelength at the 1H frequency at 300 MHz, these coils were straightforward to build and decouple. The sensitivity profiles of individual coils were highly asymmetric, as expected at this high frequency; however, the summed images from all coils were relatively uniform over the whole brain. Data were obtained with four- and eight-channel transceive arrays built using a loop configuration and compared to arrays built from straight stripline transmission lines. With both the four- and the eight-channel arrays, parallel imaging with sensitivity encoding with high reduction numbers was feasible at 7 T in the human head. A one-dimensional reduction factor of 4 was robustly achieved with an average g value of 1.25 with the eight-channel transmit/receive coils.

  16. Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

    NASA Astrophysics Data System (ADS)

    Boubela, Roland N.; Kalcher, Klaudius; Nasel, Christian; Moser, Ewald

    2014-02-01

    Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to "true" neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TR< 0.5s) scanning may help to identify and eliminate physiologic components, increasing tSNR and functional contrast. In addition, biological variability can be studied and task performance better correlated to other measures. This should increase specificity and reliability in fMRI studies. Furthermore, physiological signal changes during scanning may then be recognized as a source of information rather than a nuisance. As we are currently still undersampling the complexity of the brain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.). From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

  17. Observation of longitudinal phase space fragmentation at the TESLA test facility free-electron laser

    NASA Astrophysics Data System (ADS)

    Hüning, M.; Piot, Ph.; Schlarb, H.

    2001-12-01

    It has been reproducibly observed that the energy distribution of the beam, when fully longitudinally compressed for SASE operation, breaks up into several peaks. In this paper a description of the experimental setup, beam operating conditions, and observations is presented to enable further theoretical studies of this effect.

  18. Design and Performance of the Tesla Test Facility (TTF) Collimation System

    NASA Astrophysics Data System (ADS)

    Schlarb, H.

    2003-12-01

    To perform a-proof-of principle experiment of a SASE based Free Electron Laser a permanent magnet undulator has been installed in the TTF linac phase 1. The magnets used (NdFeB) are known to be sensitive to radiation damages if exposed to high energy electrons. Already beam losses in the order of 10-6 of the nominal TTF beam current (64μA) are critical for the undulator and could have cause an irreversible damage of its magnets after a few months of operation. The protection of the undulator against radiation has been attacked twofold: first, a two stage spoiler-absorber collimation system has been installed and second, a beam loss detection system of high sensitivity has been added to the machine protection system. The performance and the operational experience of the active and the passive protection system are discussed.

  19. Multi circular-cavity surface coil for magnetic resonance imaging of monkey's brain at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Osorio, A. I.; Solis-Najera, S. E.; Vázquez, F.; Wang, R. L.; Tomasi, D.; Rodriguez, A. O.

    2014-11-01

    Animal models in medical research has been used to study humans diseases for several decades. The use of different imaging techniques together with different animal models offers a great advantage due to the possibility to study some human pathologies without the necessity of chirurgical intervention. The employ of magnetic resonance imaging for the acquisition of anatomical and functional images is an excellent tool because its noninvasive nature. Dedicated coils to perform magnetic resonance imaging experiments are obligatory due to the improvement on the signal-to-noise ratio and reduced specific absorption ratio. A specifically designed surface coil for magnetic resonance imaging of monkey's brain is proposed based on the multi circular-slot coil. Numerical simulations of the magnetic and electric fields were also performed using the Finite Integration Method to solve Maxwell's equations for this particular coil design and, to study the behavior of various vector magnetic field configurations and specific absorption ratio. Monkey's brain images were then acquired with a research-dedicated magnetic resonance imaging system at 4T, to evaluate the anatomical images with conventional imaging sequences. This coil showed good quality images of a monkey's brain and full compatibility with standard pulse sequences implemented in research-dedicated imager.

  20. Reactivation and operation of the large six-tesla CFFF superconducting magnet

    SciTech Connect

    Hill, D.; Libera, J.; Petrick, M.

    1992-07-01

    The second MHD superconducting magnet system constructed at the Argonne National Laboratory, originally intended for use in the coal-fired plasma MHD power generation program, has been in storage at Argonne since its assembly and short-term testing a decade ago. At that time it was energized for only a few days and then decommissioned. The magnet, a 6-T dipole having an effective length of 300 cm and a tapered warm bore of 80 to 100 cm, has recently been reactivated and put into service for sea water MHD propulsion research. This report describes the technical aspects of the reactivation process, as well as the operational characterization of the reconstituted system.

  1. Reactivation and operation of the large six-tesla CFFF superconducting magnet

    SciTech Connect

    Hill, D.; Libera, J.; Petrick, M.

    1992-01-01

    The second MHD superconducting magnet system constructed at the Argonne National Laboratory, originally intended for use in the coal-fired plasma MHD power generation program, has been in storage at Argonne since its assembly and short-term testing a decade ago. At that time it was energized for only a few days and then decommissioned. The magnet, a 6-T dipole having an effective length of 300 cm and a tapered warm bore of 80 to 100 cm, has recently been reactivated and put into service for sea water MHD propulsion research. This report describes the technical aspects of the reactivation process, as well as the operational characterization of the reconstituted system.

  2. Neuroanatomical correlates of apathy in ALS using 4 Tesla diffusion tensor MRI.

    PubMed

    Woolley, Susan C; Zhang, Yu; Schuff, Norbert; Weiner, Michael W; Katz, Jonathan S

    2011-01-01

    Our objective was to determine whether apathy in amyotrophic lateral sclerosis (ALS) relates to structural changes associated with the degenerative process or disease related factors such as illness duration, physical disability, or hypoxia. Using diffusion tensor imaging (DTI) with fractional anisotropy (FA), we conducted a voxel-based analysis of whole-brain changes to investigate decline in white matter integrity as it correlates with apathy in ALS. Twenty-four patients enrolled in the study were compared with 24 age- and gender-matched controls. The relationship between FA and apathy scores was tested using a general linear model accounting for age, gender and functional disability in 16 ALS patients. Results showed that, using a spatially unbiased voxel-wise approach and the statistical map-driven region of interest (ROI), a significant negative correlation existed between FA and apathy change scores in the right anterior cingulum region, whereas ALS disease severity was significantly correlated with FA alterations in bilateral motor areas. Apathy was not correlated with clinical depression, disease duration or respiratory dysfunction. In conclusion, our findings point towards a biological basis for apathy in the anterior cingulum, consistent with research on apathy in other neurological populations.

  3. Brain iron deposition in essential tremor: a quantitative 3-Tesla magnetic resonance imaging study.

    PubMed

    Novellino, Fabiana; Cherubini, Andrea; Chiriaco, Carmelina; Morelli, Maurizio; Salsone, Maria; Arabia, Gennarina; Quattrone, Aldo

    2013-02-01

    Studies have demonstrated brain iron deposition in neurodegenerative disease and in normal aging. Data on this topic are lacking in essential tremor (ET). The aim of our study was to investigate brain iron content in patients with ET, using quantitative magnetic resonance imaging (MRI) T2*-relaxometry. We enrolled 24 patients with ET and 25 age-matched healthy controls. Subjects were examined using a 3T MRI scanner. The protocol included conventional MRI sequences and quantitative T2*-relaxometry. Whole-brain voxel-based analyses showed significant differences in T2* values in bilateral globus pallidus, substantia nigra, and in right dentate nucleus (P < .001 uncorrected). In the bilateral pallidum, differences survived family-wise-error (FWE) correction for multiple comparisons (P < .05). The present study provides the first evidence of increased brain iron accumulation in ET patients. Our results are suggestive of a possible involvement of motor systems outside of the cerebellum/cerebellar pathway and, more specifically, of the globus pallidus.

  4. Reproducibility of resting state spinal cord networks in healthy volunteers at 7 Tesla.

    PubMed

    Barry, Robert L; Rogers, Baxter P; Conrad, Benjamin N; Smith, Seth A; Gore, John C

    2016-06-01

    We recently reported our findings of resting state functional connectivity in the human spinal cord: in a cohort of healthy volunteers we observed robust functional connectivity between left and right ventral (motor) horns and between left and right dorsal (sensory) horns (Barry et al., 2014). Building upon these results, we now quantify the within-subject reproducibility of bilateral motor and sensory networks (intraclass correlation coefficient=0.54-0.56) and explore the impact of including frequencies up to 0.13Hz. Our results suggest that frequencies above 0.08Hz may enhance the detectability of these resting state networks, which would be beneficial for practical studies of spinal cord functional connectivity.

  5. Effect of slice orientation on reproducibility of fMRI motor activation at 3 Tesla.

    PubMed

    Gustard, S; Fadili, J; Williams, E J; Hall, L D; Carpenter, T A; Brett, M; Bullmore, E T

    2001-12-01

    The effect of slice orientation on reproducibility and sensitivity of 3T fMRI activation using a motor task has been investigated in six normal volunteers. Four slice orientations were used; axial, oblique axial, coronal and sagittal. We applied analysis of variance (ANOVA) to suprathreshold voxel statistics to quantify variability in activation between orientations and between subjects. We also assessed signal detection accuracy in voxels across the whole brain by using a finite mixture model to fit receiver operating characteristic (ROC) curves to the data. Preliminary findings suggest that suprathreshold cluster characteristics demonstrate high motor reproducibility across subjects and orientations, although a significant difference between slice orientations in number of activated voxels was demonstrated in left motor cortex but not cerebellum. Subtle inter-orientation differences are highlighted in the ROC analyses, which are not obvious by ANOVA; the oblique axial slice orientation offers the highest signal detection accuracy, whereas coronal slices give the lowest.

  6. Implementation of Vascular-space-occupancy (VASO) MRI at 7 Tesla

    PubMed Central

    Hua, Jun; Jones, Craig K.; Qin, Qin; van Zijl, Peter C. M.

    2012-01-01

    VASO-MRI exploits the difference between blood and tissue T1 to null blood signal and measure cerebral blood volume (CBV) changes using the residual tissue signal. VASO imaging is more difficult at higher field because of sensitivity loss due to the convergence of tissue and blood T1 values and increased contamination from BOLD effects. In addition, compared to 3T, 7T MRI suffers from increased geometrical distortions, e.g. when using echo-planar-imaging (EPI), and from increased power deposition, the latter especially problematic for the spin-echo-train sequences commonly used for VASO-MRI. Third, non-steady-state blood spin effects become substantial at 7T when only a head coil is available for radiofrequency transmit. In this study, the magnetization-transfer-enhanced-VASO (MT-VASO) approach was applied to maximize tissue-blood signal difference, which boosted SNR by 149 ± 13% (n=7) compared to VASO. Second, a 3D fast gradient-echo sequence with low flip-angle (7°) and short echo-time (1.8ms) was employed to minimize the BOLD effect and to reduce image distortion and power deposition. Finally, a magnetization-reset technique was combined with a motion-sensitized-driven-equilibrium (MSDE) approach to suppress three types of non-steady-state spins. Our initial fMRI results in normal human brains at 7T with this optimized VASO sequence showed better SNR than at 3T. PMID:22585570

  7. Phase modulated magnetoelectric delta-E effect sensor for sub-nano tesla magnetic fields

    NASA Astrophysics Data System (ADS)

    Zabel, S.; Kirchhof, C.; Yarar, E.; Meyners, D.; Quandt, E.; Faupel, F.

    2015-10-01

    We present a resonant micromechanical magnetic field sensor, which utilizes the magnetically induced change in elastic modulus, i.e., the delta-E effect. The sensor is based on magnetoelectric thin film composites, resulting in high sensitivity at room temperature and at low frequencies. The cantilever is electrically excited and read out by a 2 μm AlN piezoelectric layer. Depending on its magnetization, the 2 μm thin film of amorphous (Fe90Co10)78Si12B10 changes its elasticity, which results in a shift of the cantilever's resonance frequency. The sensor is operated in the first or second transversal bending mode at 7.6 kHz or 47.4 kHz. With a limit of detection of 140 pTHz-0.5 at 20 Hz under a magnetic bias field and 1 nTHz-0.5 without external bias field, this sensor exceeds all comparable designs by one order of magnitude.

  8. Opportunities and Challenges of 7 Tesla Magnetic Resonance Imaging: A Review.

    PubMed

    Karamat, Muhammad Irfan; Darvish-Molla, Sahar; Santos-Diaz, Alejandro

    2016-01-01

    The desire to achieve clinical ultra-high magnetic resonance imaging (MRI) systems stems from the fact that higher field strength leads to higher signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and spatial resolution. During last few years 7T MRI systems have become a quasi standard for ultra-high field MRI (UhFMRI) systems. This review presents a detailed account of opportunities and challenges associated with a clinical 7T MRI system for cranial and extracranial imaging. As with all of the previous transitions to higher field strengths, the switch from high to UhFMRI is not easy. The engineering and scientific community have to overcome challenges like magnetic field inhomogeneity, patient safety and comfort issues, and cost and related problems in order to achieve a clinically viable UhFMRI system. In addition, a large number of clinical studies are still required to show the improvements in quality of diagnostics that would come with 7T MRI, in order to bring such a research tool to the clinic.

  9. Pediatric cardiovascular interventional devices: effect on CMR images at 1.5 and 3 Tesla

    PubMed Central

    2013-01-01

    Background To predict the type and extent of CMR artifacts caused by commonly used pediatric trans-catheter devices at 1.5 T and 3 T as an aid to clinical planning and patient screening. Methods Eleven commonly used interventional, catheter-based devices including stents, septal occluders, vascular plugs and embolization coils made from either stainless steel or nitinol were evaluated ex-vivo at both 1.5T and 3T. Pulse sequences and protocols commonly used for cardiovascular magnetic resonance (CMR) were evaluated, including 3D high-resolution MR angiography (MRA), time-resolved MRA, 2D balanced-SSFP cine and 2D phase-contrast gradient echo imaging (GRE). We defined the signal void amplification factor (F) as the ratio of signal void dimension to true device dimension. F1 and F2 were measured in the long axis and short axes respectively of the device. We defined F3 as the maximum extent of the off-resonance dark band artifact on SSFP measured in the B0direction. The effects of field strength, sequence type, orientation, flip angle and phase encode direction were tested. Clinical CMR images in 3 patients with various indwelling devices were reviewed for correlation with the in-vitro findings. Results F1 and F2 were higher (p<0.05) at 3T than at 1.5T for all sequences except 3D-MRA. Stainless steel devices produced greater off-resonance artifact on SSFP compared to nitinol devices (p<0.05). Artifacts were most severe with the stainless steel Flipper detachable embolization coil (Cook Medical, Bloomington, IN), with F1 and F2 10 times greater than with stainless steel stents. The orientation of stents changed the size of off-resonance artifacts by up to two fold. Sequence type did influence the size of signal void or off-resonance artifact (p<0.05). Varying the flip angle and phase encode direction did not affect image artifact. Conclusion Stainless steel embolization coils render large zones of anatomy uninterpretable, consistent with predictions based on ex-vivo testing. Most other commonly used devices produce only mild artifact ex-vivo and are compatible with diagnostic quality in-vivo studies. Knowledge of ex-vivo device behavior can help predict the technical success or failure of CMR scans and may preempt the performance of costly, futile studies. PMID:23782716

  10. An unshielded radio-frequency atomic magnetometer with sub-femtoTesla sensitivity

    SciTech Connect

    Keder, David A.; Prescott, David W.; Conovaloff, Adam W.; Sauer, Karen L.

    2014-12-15

    We demonstrate a radio-frequency potassium-vapor magnetometer operating with sensitivities of 0.3 fT/√(Hz) at 0.5 MHz and 0.9 fT/√(Hz) at 1.31 MHz in the absence of radio-frequency and mu-metal or magnetic shielding. The use of spatially separated magnetometers, two voxels within the same cell, permits for the subtraction of common mode noise and the retention of a gradient signal, as from a local source. At 0.5 MHz the common mode noise was white and measured to be 3.4 fT/√(Hz); upon subtraction the noise returned to the values observed when the magnetometer was shielded. At 1.31 MHz, the common mode noise was from a nearby radio station and was reduced by a factor of 33 upon subtraction, limited only by the radio signal picked up by receiver electronics. Potential applications include in-the-field low-field magnetic resonance, such as the use of nuclear quadrupole resonance for the detection of explosives.

  11. Magnetic field measurements of a clinical MR imager at 1.5 tesla

    NASA Astrophysics Data System (ADS)

    Muhech, A.; Tellez, I.; Esteva, M.; Marrufo, O.; Jimenez, L.; Vazquez, F.; Taboada, J.; Rodriguez, A. O.

    2012-10-01

    In the clinical environment is mandatory to run periodically measurements of uniformity of the magnetic field produced by the magnet to assure good image quality. The phase difference method was used to measure the magnetic field uniformity of the 1.5 T scanner of the Instituto Nacional de Neurologia y Neurocirugia MVS. The uniformity field values showed that the imager performance is reasonably good for clinical imaging. Some concern was raised since results may not be good enough for magnetic resonance spectroscopy runs.

  12. MRI from 400 gauss to 1.5 tesla and beyond

    NASA Astrophysics Data System (ADS)

    Edelstein, William

    2006-03-01

    Magnetic Resonance Imaging (MRI) is arguably the most novel and important medical imaging modality since the advent of the X-ray. MRI grew out of the long development of atomic spectroscopy, atomic and molecular beam resonance and, finally, nuclear magnetic resonance (NMR) in condensed matter. The operation and economics of MRI systems depend on the performance of magnets, pulsed magnetic field gradient windings and rf (radiofrequency) coils. Physics and physicists have made critical contributions to these technologies. Superconducting magnets have come to be the magnet of choice. Magnetic gradient windings present theoretical electromagnetic and practical challenges. The need for rf antennas that resonate at high frequencies while surrounding sizable spatial regions inspired large coils producing uniform rf magnetic fields while minimizing electric field interactions with the imaging subject. This development enabled MRI at high magnetic fields. Additionally it is possible to use arrays of small rf coils to obtain MRI images with the high signal-to-noise ratio of a small surface coil and the field of view of a large coil. We recently investigated the intense acoustic noise (110 dB or more) produced in MRI scanners. Surprisingly, eddy currents induced in the magnet cryostat inner bore make a major contribution to this noise. Calculations indicate that a thin layer of Cu on the outside of the gradient assembly could substantially decrease eddy currents and help reduce noise. GE R&D work was focused on the science underlying MRI, MRI technology and the MRI product. Corporate management sometimes discourages technical publication related to evolving products because it might help rivals. Our practice of extensive publication and participation in open scientific exchange---after filing appropriate patent applications---served as quality control for company science and technology. GE conference presentations and journal publications helped establish technical leadership and determine which ideas were most important. GE scientists built reputations leading to leadership prominent within the MRI technical community. Openness underpinned a highly effective development process that enabled GE to pull ahead of competitors.

  13. Design charts for Tesla-transformer-type relativistic electron beam generators

    NASA Astrophysics Data System (ADS)

    Matsuzawa, Hidenori; Suganomata, Shinji

    1982-05-01

    The obtainable high voltage is more sensitive to the tuning between the primary and the secondary circuit than to the coupling between them. This is confirmed both numerically and experimentally. Fundamental designing charts and a simple diode chamber are presented.

  14. RF Control System for the SC cavity of the Tesla Test Facility Injector

    NASA Astrophysics Data System (ADS)

    Mosnier, A.; Chel, S.; Phung Ngoc, B.; Tessier, J. M.

    1997-05-01

    The superconducting cavity of the TTF injector, which operates in pulsed mode, must accelerate the non relativistic electron beam to an energy of 10 to 15 MeV. Lorentz forces and microphonics detunings are the major sources of cavity field fluctuation. In order to achieve amplitude and phase stabilities much smaller than 10-3 and 1 degree, an analog feedback system, mainly based on a self excited loop and I/Q modulators, has been developed. After a description of the RF control module, various measurements without and with beam are reported and compared with numerical simulations.

  15. Magnetic resonance imaging of rodent spinal cord with an improved performance coil at 7 Tesla

    NASA Astrophysics Data System (ADS)

    Solis-Najera, S. E.; Rodriguez, A. O.

    2014-11-01

    Magnetic Resonance Imaging of animal models provide reliable means to study human diseases. The image acquisition particularly determined by the radio frequency coil to detect the signal emanated from a particular region of interest. A scaled-down version of the slotted surface coil was built based on the previous results of a magnetron-type surface coil for human applications. Our coil prototype had a 2 cm total diameter and six circular slots and was developed for murine spinal cord at 7 T. Electromagnetic simulations of the slotted and circular coils were also performed to compute the spatially dependent magnetic and electric fields using a simulated saline-solution sphere. The quality factor of both coils was experimentally measured giving a lower noise figure and a higher quality factor for the slotted coil outperforming the circular coil. Images of the spinal cord of a rat were acquired using standard pulse sequences. The slotted surface coil can be a good tool for spinal cord rat imaging using conventional pulse sequences at 7 T.

  16. Physiological effects of cigarette smoking in the limbic system revealed by 3 tesla magnetic resonance spectroscopy.

    PubMed

    Mennecke, Angelika; Gossler, Andrea; Hammen, Thilo; Dörfler, Arnd; Stadlbauer, Andreas; Rösch, Julie; Kornhuber, Johannes; Bleich, Stefan; Dölken, Marc; Thürauf, Norbert

    2014-10-01

    Several studies and recent models of effects of nicotine, the main addictive and psychoactive component in tobacco, point to action of the drug on the limbic system during maintenance of addiction, either direct or indirect via projections from the ventral tegmental area. The objective of this study was to demonstrate physiological effects of cigarette smoking on the hippocampus and the grey matter of the dorsal anterior cingulate cortex in the human brain with regard to addiction and withdrawal. This aim was achieved by group comparisons of results of magnetic resonance spectroscopy between non-smokers, smokers and smokers during withdrawal. 12 smokers and 12 non-smokers were measured with single voxel proton magnetic resonance spectroscopy for total N-acetyl aspartate, glutamate and glutamine, choline-containing compounds, myo-inositol and total creatine in the right and the left hippocampus and in the right and the left dorsal anterior cingulate cortex. Smokers were examined twice, first during regular cigarette smoking and second on the third day of nicotine withdrawal. The ratios to total creatine were used for better reliability. In our study, Glx/tCr was significantly increased and tCho/tCr was significantly decreased in the left cingulate cortex in smokers compared to non-smokers (p = 0.01, both). Six out of seven smokers showed normalization of the Glx/tCr in the left cingulate cortex during withdrawal. Although these results are preliminary due to the small sample size, our results confirm the assumption that cigarette smoking interferes directly or indirectly with the glutamate circuit in the dorsal anterior cingulate cortex.

  17. An unshielded radio-frequency atomic magnetometer with sub-femtoTesla sensitivity

    NASA Astrophysics Data System (ADS)

    Keder, David A.; Prescott, David W.; Conovaloff, Adam W.; Sauer, Karen L.

    2014-12-01

    We demonstrate a radio-frequency potassium-vapor magnetometer operating with sensitivities of 0.3 fT/ √{ Hz } at 0.5 MHz and 0.9 fT/ √{ Hz } at 1.31 MHz in the absence of radio-frequency and mu-metal or magnetic shielding. The use of spatially separated magnetometers, two voxels within the same cell, permits for the subtraction of common mode noise and the retention of a gradient signal, as from a local source. At 0.5 MHz the common mode noise was white and measured to be 3.4 fT/ √{ Hz } ; upon subtraction the noise returned to the values observed when the magnetometer was shielded. At 1.31 MHz, the common mode noise was from a nearby radio station and was reduced by a factor of 33 upon subtraction, limited only by the radio signal picked up by receiver electronics. Potential applications include in-the-field low-field magnetic resonance, such as the use of nuclear quadrupole resonance for the detection of explosives.

  18. Stroking or Buzzing? A Comparison of Somatosensory Touch Stimuli Using 7 Tesla fMRI.

    PubMed

    van der Zwaag, Wietske; Gruetter, Rolf; Martuzzi, Roberto

    2015-01-01

    Studying body representations in the brain helps us to understand how we humans relate to our own bodies. The in vivo mapping of the somatosensory cortex, where these representations are found, is greatly facilitated by the high spatial resolution and high sensitivity to brain activation available at ultra-high field. In this study, the use of different stimulus types for somatotopic mapping of the digits at ultra-high field, specifically manual stroking and mechanical stimulation, was compared in terms of sensitivity and specificity of the brain responses. Larger positive responses in digit regions of interest were found for manual stroking than for mechanical stimulation, both in terms of average and maximum t-value and in terms of number of voxels with significant responses to the tactile stimulation. Responses to manual stroking were higher throughout the entire post-central sulcus, but the difference was especially large on its posterior wall, i.e. in Brodmann area 2. During mechanical stimulation, cross-digit responses were more negative than during manual stroking, possibly caused by a faster habituation to the stimulus. These differences indicate that manual stroking is a highly suitable stimulus for fast somatotopic mapping procedures, especially if Brodmann area 2 is of interest.

  19. 27 CFR 200.55 - Content.

    Code of Federal Regulations, 2011 CFR

    1999-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 1999-04-01 1999-04-01 false Content. 200.55 Section 200.55 ALCOHOL, TOBACCO AND OTHER EXCISE TAXES-Continued RULES OF PRACTICE IN PERMIT PROCEEDINGS Hearing Procedure Citations § 200.55 Content. (a) Citation for the suspension, revocation or annulment...

  20. Design and evaluation of a hybrid radiofrequency applicator for magnetic resonance imaging and RF induced hyperthermia: electromagnetic field simulations up to 14.0 Tesla and proof-of-concept at 7.0 Tesla.

    PubMed

    Winter, Lukas; Özerdem, Celal; Hoffmann, Werner; Santoro, Davide; Müller, Alexander; Waiczies, Helmar; Seemann, Reiner; Graessl, Andreas; Wust, Peter; Niendorf, Thoralf

    2013-01-01

    This work demonstrates the feasibility of a hybrid radiofrequency (RF) applicator that supports magnetic resonance (MR) imaging and MR controlled targeted RF heating at ultrahigh magnetic fields (B0≥7.0T). For this purpose a virtual and an experimental configuration of an 8-channel transmit/receive (TX/RX) hybrid RF applicator was designed. For TX/RX bow tie antenna electric dipoles were employed. Electromagnetic field simulations (EMF) were performed to study RF heating versus RF wavelength (frequency range: 64 MHz (1.5T) to 600 MHz (14.0T)). The experimental version of the applicator was implemented at B0 = 7.0T. The applicators feasibility for targeted RF heating was evaluated in EMF simulations and in phantom studies. Temperature co-simulations were conducted in phantoms and in a human voxel model. Our results demonstrate that higher frequencies afford a reduction in the size of specific absorption rate (SAR) hotspots. At 7T (298 MHz) the hybrid applicator yielded a 50% iso-contour SAR (iso-SAR-50%) hotspot with a diameter of 43 mm. At 600 MHz an iso-SAR-50% hotspot of 26 mm in diameter was observed. RF power deposition per RF input power was found to increase with B0 which makes targeted RF heating more efficient at higher frequencies. The applicator was capable of generating deep-seated temperature hotspots in phantoms. The feasibility of 2D steering of a SAR/temperature hotspot to a target location was demonstrated by the induction of a focal temperature increase (ΔT = 8.1 K) in an off-center region of the phantom. Temperature simulations in the human brain performed at 298 MHz showed a maximum temperature increase to 48.6C for a deep-seated hotspot in the brain with a size of (19×23×32)mm(3) iso-temperature-90%. The hybrid applicator provided imaging capabilities that facilitate high spatial resolution brain MRI. To conclude, this study outlines the technical underpinnings and demonstrates the basic feasibility of an 8-channel hybrid TX/RX applicator that supports MR imaging, MR thermometry and targeted RF heating in one device.

  1. A Motion and Flow Insensitive Adiabatic T2-Preparation Module for Cardiac MR Imaging at 3 Tesla

    PubMed Central

    Jenista, Elizabeth R.; Rehwald, Wolfgang G.; Chen, Enn-Ling; Kim, Han W.; Klem, Igor; Parker, Michele A.; Kim, Raymond J.

    2014-01-01

    A versatile method for generating T2-weighting is a T2-preparation (T2-prep) module, which has been used successfully for cardiac imaging at 1.5T. Although it has been applied at 3T, higher fields (B0 ≥ 3T) can degrade B0 and B1 homogeneity and result in non-uniform magnetization preparation. For cardiac imaging, blood flow and cardiac motion may further impair magnetization preparation. In this study, a novel T2-prep module containing multiple adiabatic B1-insensitive refocusing (BIREF-1) pulses is introduced and compared with three previously described modules (a: composite MLEV4, b: modified BIR-4 (mBIR-4), and c: Silver-Hoult–pair). In the static phantom, the proposed module provided similar or better B0 and B1 insensitivity than the other modules. In human subjects (n=21), quantitative measurement of image signal coefficient of variation (CV), reflecting overall image inhomogeneity, was lower for the proposed module (0.10) than for MLEV4 (0.15, p<0.0001), mBIR-4 (0.27, p<0.0001), and Silver-Hoult–pair (0.14, p=0.001) modules. Similarly, qualitative analysis revealed that the proposed module had the best image quality scores and ranking (both, p<0.0001). In conclusion, we present a new T2-preparation module, which is shown to be robust for cardiac imaging at 3T in comparison with existing methods. PMID:23213005

  2. 76 FR 33402 - Tesla Motors, Inc.; Receipt of Petition for Renewal of Temporary Exemption from the Advanced Air...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... crashes. \\2\\ See 65 FR 30680 (May 12, 2000). The issuance of the advanced air bag requirements was a... developing advanced air bag systems. \\3\\ See, e.g., grant of petition to Panoz, 72 FR 28759 (May 22, 2007), or grant of petition to Koenigsegg, 72 FR 17608 (April 9, 2007). Notwithstanding those...

  3. In vivo measurement of local aortic pulse-wave velocity in mice with MR microscopy at 17.6 Tesla.

    PubMed

    Herold, Volker; Parczyk, Marco; Mörchel, Philipp; Ziener, Christian H; Klug, Gert; Bauer, Wolfgang R; Rommel, Eberhard; Jakob, Peter M

    2009-06-01

    Transgenic mouse models of human diseases have gained increasing importance in the pathophysiology of cardiovascular diseases (CVD). As an indirect measure of vascular stiffness, aortic pulse-wave velocity (PWV) is an important predictor of cardiovascular risk. This study presents an MRI approach that uses a flow area method to estimate local aortic pulse-wave velocity at different sites in the murine aorta. By simultaneously measuring the cross-sectional area and the through-plane velocity with a phase-contrast CINE method, it was possible to measure average values for the PWV in the ascending and descending aorta within the range of 2.4-4.3 m/s for C57BL/6J mice (ages 2 and 8 months) and apoE-knockout mice (age 8 months). Statistically significant differences of the mean values of the PWV of both groups could be determined. By repeating CINE measurements with a time delay of 1 ms between two subsequent data sets, an effective temporal resolution of 1000 frames/s (fps) could be achieved.

  4. Age-related changes in anterior cingulate cortex glutamate in schizophrenia: A (1)H MRS Study at 7 Tesla.

    PubMed

    Brandt, Allison S; Unschuld, Paul G; Pradhan, Subechhya; Lim, Issel Anne L; Churchill, Gregory; Harris, Ashley D; Hua, Jun; Barker, Peter B; Ross, Christopher A; van Zijl, Peter C M; Edden, Richard A E; Margolis, Russell L

    2016-04-01

    The extent of age-related changes in glutamate and other neurometabolites in the anterior cingulate cortex (ACC) in individuals with schizophrenia remain unclear. Magnetic resonance spectroscopy (MRS) at 7 T, which yields precise measurements of various metabolites and can distinguish glutamate from glutamine, was used to determine levels of ACC glutamate and other metabolites in 24 individuals with schizophrenia and 24 matched controls. Multiple regression analysis revealed that ACC glutamate decreased with age in patients but not controls. No changes were detected in levels of glutamine, N-acetylaspartate, N-acetylaspartylglutamic acid, myo-inositol, GABA, glutathione, total creatine, and total choline. These results suggest that age may be an important modifier of ACC glutamate in schizophrenia. PMID:26925800

  5. Proton echo-planar spectroscopic imaging of J-coupled resonances in human brain at 3 and 4 Tesla.

    PubMed

    Posse, Stefan; Otazo, Ricardo; Caprihan, Arvind; Bustillo, Juan; Chen, Hongji; Henry, Pierre-Gilles; Marjanska, Malgorzata; Gasparovic, Charles; Zuo, Chun; Magnotta, Vincent; Mueller, Bryon; Mullins, Paul; Renshaw, Perry; Ugurbil, Kamil; Lim, Kelvin O; Alger, Jeffry R

    2007-08-01

    In this multicenter study, 2D spatial mapping of J-coupled resonances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-suppressed (WS) data were acquired in 8.5 min with 1-cm(3) spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral fitting in reference to a non-WS (NWS) scan was performed with LCModel using correction for relaxation attenuation and partial-volume effects. The concentrations of total choline (tCho), creatine + phosphocreatine (Cr+PCr), glutamate (Glu), glutamate + glutamine (Glu+Gln), myo-inositol (Ins), NAA, NAA+NAAG, and two macromolecular resonances at 0.9 and 2.0 ppm were mapped with mean Cramer-Rao lower bounds (CRLBs) between 6% and 18% and approximately 150-cm(3) sensitive volumes. Aspartate, GABA, glutamine (Gln), glutathione (GSH), phosphoethanolamine (PE), and macromolecules (MMs) at 1.2 ppm were also mapped, although with larger mean CRLBs between 30% and 44%. The CRLBs at 4T were 19% lower on average as compared to 3T, consistent with a higher signal-to-noise ratio (SNR) and increased spectral resolution. Metabolite concentrations were in the ranges reported in previous studies. Glu concentration was significantly higher in gray matter (GM) compared to white matter (WM), as anticipated. The short acquisition time makes this methodology suitable for clinical studies.

  6. Quantitative assessment of trabecular bone micro-architecture of the wrist via 7 Tesla MRI: preliminary results

    PubMed Central

    Wang, Ligong; Liang, Guoyuan; Babb, James S.; Wiggins, Graham C.; Saha, Punam K.; Regatte, Ravinder R.

    2013-01-01

    Object The goal of this study was to determine the feasibility of performing quantitative 7T magnetic resonance imaging (MRI) assessment of trabecular bone micro-architecture of the wrist, a common fracture site. Materials and methods The wrists of 4 healthy subjects (1 woman, 3 men, 28±8.9 years) were scanned on a 7T whole body MR scanner using a 3D fast low-angle shot (FLASH) sequence (TR/TE = 20/4.5ms, 0.169 × 0.169 × 0.5mm). Trabecular bone was segmented and divided into 4 or 8 angular subregions. Total bone volume (TBV), bone volume fraction (BVF), surface-curve ratio (SC), and erosion index (EI) were computed. Subjects were scanned twice to assess measurement reproducibility. Results Group mean subregional values for TBV, BVF, SC, and EI (8 subregion analysis) were as follows: 8489 ± 3686, 0.27 ± 0.045, 9.61 ± 6.52; and 1.43 ± 1.25. Within each individual, there was subregional variation in TBV, SC, and EI (>5%), but not BVF (<5%). Intersubject variation (≥12%) existed for all parameters. Within-subject coefficients of variation were ≤10%. Conclusion This is the first study to perform quantitative 7T MRI assessment of trabecular bone micro-architecture of the wrist. This method could be utilized to study perturbations in bone structure in subjects with osteoporosis or other bone disorders. PMID:21544680

  7. 1.5 Tesla MRI-Conditional 12-lead ECG for MR Imaging and Intra-MR Intervention

    PubMed Central

    Tse, Zion Tsz Ho; Dumoulin, Charles L.; Clifford, Gari D.; Schweitzer, Jeff; Qin, Lei; Oster, Julien; Jerosch-Herold, Michael; Kwong, Raymond Y.; Michaud, Gregory; Stevenson, William G.; Schmidt, Ehud J.

    2013-01-01

    Propose High-fidelity 12-lead Electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MR imaging. Issues in obtaining non-corrupted ECGs inside MRI include a superimposed Magneto-Hydro-Dynamic (MHD) voltage, gradient-switching induced-voltages, and radiofrequency (RF) heating. These problems increase with magnetic field. We intended to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system. Methods The system was constructed, including transmission-lines to reduce radio-frequency induction, and switching-circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove MHD. The system was tested on ten (one exercising) volunteers and four arrhythmia patients. Results Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). MHD removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true ST segment. In premature-ventricular-contraction (PVC) patients, clean ECGs separated PVC and sinus-rhythm beats. Measured heating was <1.5 C0. The system reliably acquired multiphase (SSFP) wall-motion-cine and phase-contrast-cine scans, including in subjects where 4-lead gating failed. The system required a minimum TR of 4ms to allow robust ECG processing. Conclusion High-fidelity intra-MRI 12-lead ECG is possible. PMID:23580148

  8. Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

    2011-02-01

    Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS.

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

    PubMed

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

    2015-01-01

    Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS heating effects holds considerable promise. PMID:26237218

  10. Human aortic endothelial cell labeling with positive contrast gadolinium oxide nanoparticles for cellular magnetic resonance imaging at 7 Tesla.

    PubMed

    Loai, Yasir; Sakib, Nurus; Janik, Rafal; Foltz, Warren D; Cheng, Hai-Ling Margaret

    2012-04-01

    Positive T₁ contrast using gadolinium (Gd) contrast agents can potentially improve detection of labeled cells on magnetic resonance imaging (MRI). Recently, gadolinium oxide (Gd₂O₃) nanoparticles have shown promise as a sensitive T₁ agent for cell labeling at clinical field strengths compared to conventional Gd chelates. The objective of this study was to investigate Gado CELLTrack, a commercially available Gd₂O₃ nanoparticle, for cell labeling and MRI at 7 T. Relaxivity measurements yielded r1  =  4.7 s⁻¹ mM⁻¹ and r₂/r₁  =  6.2. Human aortic endothelial cells were labeled with Gd₂O₃ at various concentrations and underwent MRI from 1 to 7 days postlabeling. The magnetic resonance relaxation times T₁ and T₂ of labeled cell pellets were measured. Cellular contrast agent uptake was quantified by inductively coupled plasma-atomic emission spectroscopy, which showed very high uptake compared to conventional Gd compounds. MRI demonstrated significant positive T₁ contrast and stable labeling on cells. Enhancement was optimal at low Gd concentrations, attained in the 0.02 to 0.1 mM incubation concentration range (corresponding cell uptake was 7.26 to 34.1 pg Gd/cell). Cell viability and proliferation were unaffected at the concentrations tested and up to at least 3 days postlabeling. Gd₂O₃ is a promising sensitive and stable positive contrast agent for cellular MRI at 7 T.

  11. MR imaging and cervical fixation devices: evaluation of ferromagnetism, heating, and artifacts at 1.5 Tesla.

    PubMed

    Shellock, F G

    1996-01-01

    The purpose of this study was to assess ferromagnetism, heating, and artifacts for cervical fixation devices exposed to a 1.5 T MR system. Cervical fixation devices (three halos, one tong and two halo vests) were evaluated for compatibility with MR procedures. Ferromagnetism was determined using a previously described technique. Heating was evaluated by measuring temperatures at various positions on the cervical fixation devices while applied to a volunteer subject before and during the use of various pulse sequences, including an magnetization transfer contrast (MTC) sequence. Artifacts associated with routine clinical MR imaging of the cervical spine were qualitatively evaluated with the cervical fixation devices applied to a volunteer subject. None of the devices displayed attraction to the magnetic field. The temperature changes were +/-1.5 degrees C in each instance. The MTC pulse sequence produced a sensation of "heating" the skull pins that may have been caused by vibration of the cervical fixation device. The MR images of the cervical spine were obtained without apparent artifacts using each routine, clinical pulse sequence. The lack of ferromagnetism, negligible heating, and capability of obtaining diagnostically acceptable studies of the cervical spine indicate that MR imaging performed at 1.5 T or less may be conducted safely in patients with each of the cervical fixation devices tested using conventional pulse sequences. PMID:9071001

  12. Effective arrangement of separated transmit-only/receive-only RF coil for improvement of B1 homogeneity at 7 Tesla

    NASA Astrophysics Data System (ADS)

    Im, Geun Ho; Seo, Jeong-Hoon; Kim, Kyoung-Nam; Heo, Phil; Chung, Julius Juhyun; Jang, Moon-Sun; Lee, Jung Hee; Kim, Jae-Hun; Kim, Sun I.

    2014-09-01

    This article presents an effective arrangement with shifted transmit (Tx)-only and receive (Rx)-only (TORO) radiofrequency (RF) coils in a single-channel surface coil for improving the magnetic flux ( B 1) homogeneity in an ultra-high field (UHF) magnetic resonance imaging (MRI) scanner. The proposed new methodology for the coil arrangement using the shifted TORO RF coils was demonstrated for coils with 50-mm, 100-mm, and 150-mm-square surfaces and the results were compared to those for general Tx/Rx surface coils with the same dimensions. The computational analysis indicated that a homogeneous B1 field was achieved when the Rx-only coil was shifted in the two-dimensional xy-plane away from the Tx-only coils. Because the proposed coil configuration provides a unique opportunity for increasing the B 1 homogeneity, this feature is likely to increase the feasibility via new coil arrangements of UHF surface design and fabrication.

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

    PubMed Central

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

    2015-01-01

    Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS heating effects holds considerable promise. PMID:26237218

  14. Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

    PubMed Central

    Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

    2013-01-01

    Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

  15. Qualitative Evaluation of a High-Resolution 3D Multi-Sequence Intracranial Vessel Wall Protocol at 3 Tesla MRI

    PubMed Central

    Yang, Wenjie; van der Kolk, Anja G.; Abrigo, Jill; Lee, Ka Lok; Chu, Winnie Chiu Wing; Zwanenburg, Jaco J. M.; Siero, Jeroen C. W.; Wong, Ka Sing; Hendrikse, Jeroen; Chen, Fiona Xiang Yan

    2016-01-01

    Background and Purpose Intracranial vessel wall imaging using MRI has great potential as a clinical method for assessing intracranial atherosclerosis. The purpose of the current study was to compare three 3T MRI vessel wall sequences with different contrast weightings (T1w, PD, T2w) and dedicated sagittal orientation perpendicular to the middle cerebral artery, to the reconstructed sagittal image from a transverse 3D T1w volumetric isotropically reconstructed turbo spin-echo acquisition (VIRTA), and provide a clinical recommendation. Materials and Methods The above-mentioned sequences were acquired in 10 consecutive Chinese ischemic stroke or TIA patients (age: 68 years, sex: 4 females) with angiographic-confirmed MCA stenosis at 3T. Institutional review board approval was obtained. Two raters qualitatively scored all images on overall image quality, presence of artifacts, and visibility of plaques. Data were compared using Repeated measures ANOVA and Sidak’s adjusted post hoc tests. Results All sequences except the T2w sequence were able to depict the walls of the large vessels of the Circle of Willis (p<0.05). T1w sagittal oblique VIRTA showed significantly more artifacts (p<0.01). Peripherally located plaques were sometimes missed on the sagittal sequences, but could be appreciated on the transverse T1w VIRTA. Conclusion With the 3T multi-sequence vessel wall protocol we were able to assess the intracranial plaque with two different image contrast weightings. The sequence of preference to include in a clinical protocol would be the transverse 3D T1w VIRTA based on absence of artifacts, larger coverage including the whole Circle of Willis, and excellent lesion depiction. PMID:27532106

  16. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla

    NASA Astrophysics Data System (ADS)

    Stier, Andreas V.; McCreary, Kathleen M.; Jonker, Berend T.; Kono, Junichiro; Crooker, Scott A.

    2016-02-01

    In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately -230 μeV T-1 (g-factor ~=-4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radii of ~1.53 and ~1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). These results highlight the utility of high magnetic fields for understanding new two-dimensional materials.

  17. 0.2-Tesla magnetic resonance imaging of internal lesions of the knee joint: a prospective arthroscopically controlled clinical study.

    PubMed

    Riel, K A; Reinisch, M; Kersting-Sommerhoff, B; Hof, N; Merl, T

    1999-01-01

    The results of magnetic resonance imaging (MRI) were compared with those of arthroscopy in a prospective series of 244 patients. A dedicated system for MRI of limbs and peripheral joints--the 0.2-T Artoscan (Esaote, Italy)--was used for imaging knee joint lesions. T1-weighted spin-echo sagittal images, T2-weighted gradient-echo coronal images, and axial views for lesions of the femoropatellar joint were acquired. Paraxial sagittal and oblique coronal views were obtained for imaging of the cruciate ligaments. This protocol allowed excellent visualization of the cruciate ligaments and medial and lateral meniscus in almost all patients. Compared with arthroscopy performed within 48 h after imaging, the sensitivity, specificity, and accuracy were respectively 93%, 97%, and 95% for tears of the medial meniscus; 82%, 96%, and 93% for tears of the lateral meniscus; 100%, 100%, and 100% for tears of the posterior cruciate ligament; 98%, 98%, and 97% for tears of the anterior cruciate ligament; and 72%, 100%, and 92% for full-thickness articular cartilage lesions. The examination can be performed within 30-45 min at lower cost than diagnostic arthroscopy. MRI with a 0.2-T magnet is a safe and valuable adjunct to the clinical examination of the knee and an aid to efficient preoperative planning.

  18. Fast glomerular quantification of whole ex vivo mouse kidneys using Magnetic Resonance Imaging at 9.4 Tesla.

    PubMed

    Chacon-Caldera, Jorge; Geraci, Stefania; Krämer, Philipp; Cullen-McEwen, Luise; Bertram, John F; Gretz, Norbert; Schad, Lothar R

    2016-03-01

    A method to measure total glomerular number (Nglom) in whole mouse kidneys using MRI is presented. The method relies on efficient acquisition times. A 9.4 T preclinical MRI system with a surface cryogenic coil and a 3D gradient echo sequence were used to image nine whole ex vivo BALB/c mouse kidneys labelled with cationized-ferritin (CF). A novel method to segment the glomeruli was developed. The quantification of glomeruli was achieved by identifying and fitting the probability distribution of glomeruli thus reducing variations due to noise. For validation, Nglom of the same kidneys were also obtained using the gold standard: design-based stereology. Excellent agreement was found between the MRI and stereological measurements of Nglom, with values differing by less than 4%: (mean ± SD) MRI = 15 606±1 178; stereology = 16 273±1 523. Using a robust segmentation method and a reliable quantification method, it was possible to acquire Nglom with a scanning time of 33minutes and 20seconds. This was more than 8 times faster than previously presented MRI-based methods. Thus, an efficient approach to measure Nglom ex vivo in health and disease is provided. PMID:26777317

  19. Improved Ion Optics for Introduction of Ions into a 9.4 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Chen, Yu; Leach, Franklin E.; Kaiser, Nathan K.; Dang, Xibei; Ibrahim, Yehia M.; Norheim, Randolph V.; Anderson, Gordon A.; Smith, Richard D.; Marshall, Alan G.

    2014-01-01

    Enhancements to the ion source and transfer optics of our 9.4 T FT-ICR mass spectrometer have resulted in improved ion transmission efficiency for more sensitive mass measurement of complex mixtures at the MS and MS/MS levels. The tube lens/skimmer has been replaced by a dual ion funnel and the following octopole by a quadrupole for reduced ion cloud radial expansion before transmission into a mass-selective quadrupole. The number of ions that reach the ICR cell is increased by an order of magnitude for the funnel/quadrupole relative to the tube lens/skimmer/octopole. PMID:25601704

  20. Whole-Body Magnetic Resonance Angiography at 3 Tesla Using a Hybrid Protocol in Patients with Peripheral Arterial Disease

    SciTech Connect

    Nielsen, Yousef W.; Eiberg, Jonas P.; Logager, Vibeke B.; Schroeder, Torben V.; Just, Sven; Thomsen, Henrik S.

    2009-09-15

    The purpose of this study was to determine the diagnostic performance of 3T whole-body magnetic resonance angiography (WB-MRA) using a hybrid protocol in comparison with a standard protocol in patients with peripheral arterial disease (PAD). In 26 consecutive patients with PAD two different protocols were used for WB-MRA: a standard sequential protocol (n = 13) and a hybrid protocol (n = 13). WB-MRA was performed using a gradient echo sequence, body coil for signal reception, and gadoterate meglumine as contrast agent (0.3 mmol/kg body weight). Two blinded observers evaluated all WB-MRA examinations with regard to presence of stenoses, as well as diagnostic quality and degree of venous contamination in each of the four stations used in WB-MRA. Digital subtraction angiography served as the method of reference. Sensitivity for detecting significant arterial disease (luminal narrowing {>=} 50%) using standard-protocol WB-MRA for the two observers was 0.63 (95%CI: 0.51-0.73) and 0.66 (0.58-0.78). Specificities were 0.94 (0.91-0.97) and 0.96 (0.92-0.98), respectively. In the hybrid protocol WB-MRA sensitivities were 0.75 (0.64-0.84) and 0.70 (0.58-0.8), respectively. Specificities were 0.93 (0.88-0.96) and 0.95 (0.91-0.97). Interobserver agreement was good using both the standard and the hybrid protocol, with {kappa} = 0.62 (0.44-0.67) and {kappa} = 0.70 (0.59-0.79), respectively. WB-MRA quality scores were significantly higher in the lower leg using the hybrid protocol compared to standard protocol (p = 0.003 and p = 0.03, observers 1 and 2). Distal venous contamination scores were significantly lower with the hybrid protocol (p = 0.02 and p = 0.01, observers 1 and 2). In conclusion, hybrid-protocol WB-MRA shows a better diagnostic performance than standard protocol WB-MRA at 3 T in patients with PAD.

  1. High field (9.4 Tesla) magnetic resonance imaging of cortical grey matter lesions in multiple sclerosis.

    PubMed

    Schmierer, Klaus; Parkes, Harold G; So, Po-Wah; An, Shu F; Brandner, Sebastian; Ordidge, Roger J; Yousry, Tarek A; Miller, David H

    2010-03-01

    Multiple sclerosis is an inflammatory, degenerative disease of the central nervous system. The most obvious pathological change in multiple sclerosis is multifocal demyelination of the white matter, but grey matter demyelination may be of equal or even greater importance for its clinical manifestations. In order to assess the pathogenetic role of lesions in the grey and white matter, and to explore the association between demyelinated and non-lesional brain tissue, tools are needed to depict each of these tissue components accurately in vivo. Due to its sensitivity in detecting white matter lesions, T(2)-weighted magnetic resonance imaging at 1.5 T is important in the diagnosis of multiple sclerosis. However, magnetic resonance imaging at 1.5 T largely fails to detect grey matter lesions. In this study, we used T(2)-weighted magnetic resonance imaging at 9.4 T to detect grey matter lesions in fixed post-mortem multiple sclerosis motor cortex. Furthermore, we produced T(1), T(2) and magnetization transfer ratio maps, and correlated these indices with quantitative histology [neuronal density, intensity of immunostaining for myelin basic protein (reflecting myelin content) and phosphorylated neurofilament (reflecting axonal area)] using t-tests and multivariate regression. In 21 tissue samples, 28 cortical grey matter lesions were visible on both T(2)-weighted magnetic resonance imaging and sections immunostained for myelin basic protein, 15/28 being mixed white and grey matter and 11/28 subpial cortical grey matter lesions; 2/28 cortical grey matter lesions involved all layers of the cortex. Compared with non-lesional cortex, cortical grey matter lesions showed reduction of neuronal density (98/mm(2), SD = 34/mm(2;) versus 129/mm(2), SD = 44; P < 0.01), phosphorylated neurofilament (1/transmittance = 1.16; SD = 0.09 versus 1.24; SD = 0.1; P < 0.01) and magnetization transfer ratio (31.1 pu; SD = 11.9 versus 37.5 pu; SD = 8.7; P = 0.01), and an increase of T(2) (25.9; SD = 5 versus 22.6 ms; SD = 4.7; P < 0.01). Associations were detected between phosphorylated neurofilament and myelin basic protein (r = 0.58, P < 0.01), myelin basic protein and T(2) (r = -0.59, P < 0.01), and neuronal density and T(1) (r = -0.57, P < 0.01). All indices correlated with duration of tissue fixation, however, including the latter in the analysis did not fundamentally affect the associations described. Our data show that T(2)-weighted magnetic resonance imaging at 9.4 T enables detection of cortical grey matter lesion in post-mortem multiple sclerosis brain. The quantitative associations suggest that in cortical grey matter T(1) may be a predictor of neuronal density, and T(2) of myelin content (and-secondarily-axons). Successful translation of these results into in vivo studies using high field magnetic resonance imaging (e.g. 3 T and 7 T) will improve the assessment of cortical pathology and thereby have an impact on the diagnosis and natural history studies of patients with multiple sclerosis, as well as clinical trial designs for putative treatments to prevent cortical demyelination and neuronal loss.

  2. A high resolution 7-Tesla resting-state fMRI test-retest dataset with cognitive and physiological measures.

    PubMed

    Gorgolewski, Krzysztof J; Mendes, Natacha; Wilfling, Domenica; Wladimirow, Elisabeth; Gauthier, Claudine J; Bonnen, Tyler; Ruby, Florence J M; Trampel, Robert; Bazin, Pierre-Louis; Cozatl, Roberto; Smallwood, Jonathan; Margulies, Daniel S

    2015-01-01

    Here we present a test-retest dataset of functional magnetic resonance imaging (fMRI) data acquired at rest. 22 participants were scanned during two sessions spaced one week apart. Each session includes two 1.5 mm isotropic whole-brain scans and one 0.75 mm isotropic scan of the prefrontal cortex, giving a total of six time-points. Additionally, the dataset includes measures of mood, sustained attention, blood pressure, respiration, pulse, and the content of self-generated thoughts (mind wandering). This data enables the investigation of sources of both intra- and inter-session variability not only limited to physiological changes, but also including alterations in cognitive and affective states, at high spatial resolution. The dataset is accompanied by a detailed experimental protocol and source code of all stimuli used.

  3. Contributors to contrast between glioma and brain tissue in chemical exchange saturation transfer sensitive imaging at 3 Tesla.

    PubMed

    Scheidegger, Rachel; Wong, Eric T; Alsop, David C

    2014-10-01

    Off-resonance saturation transfer images have shown intriguing differences in intensity in glioma compared to normal brain tissues. Interpretation of these differences is complicated, however, by the presence of multiple sources of exchanging magnetization including amide, amine, and hydroxyl protons, asymmetric magnetization transfer contrast (MTC) from macromolecules, and various protons with resonances in the aliphatic spectral region. We report a study targeted at separating these components and identifying their relative contributions to contrast in glioma. Off-resonance z-spectra at several saturation powers and durations were obtained from 6 healthy controls and 8 patients with high grade glioma. Results indicate that broad macromolecular MTC in normal brain tissue is responsible for the majority of contrast with glioma. Amide exchange could be detected with lower saturation power than has previously been reported in glioma, but it was a weak signal source with no detectable contrast from normal brain tissue. At higher saturation powers, amine proton exchange was a major contributor to the observed signal but showed no significant difference from normal brain. Robust acquisition strategies that effectively isolate the contributions of broad macromolecular MTC asymmetry from amine exchange were demonstrated that may provide improved contrast between glioma and normal tissue. PMID:24857712

  4. Metastability exchange optical pumping of 3He gas up to hundreds of millibars at 4.7 Tesla

    NASA Astrophysics Data System (ADS)

    Nikiel-Osuchowska, Anna; Collier, Guilhem; Głowacz, Bartosz; Pałasz, Tadeusz; Olejniczak, Zbigniew; Wȩglarz, Władysław P.; Tastevin, Geneviève; Nacher, Pierre-Jean; Dohnalik, Tomasz

    2013-09-01

    Metastability exchange optical pumping (MEOP) is experimentally investigated in 3He at 4.7 T, at room temperature and for gas pressures ranging from 1 to 267 mbar. The 23S-23P transition at 1083 nm is used for optical pumping and for detection of the laser-induced orientation of 3He atoms in the rf discharge plasma. The collisional broadening rate is measured (12.0 ± 0.4 MHz mbar-1 FHWM) and taken into account for accurate absorption-based measurements of both nuclear polarization in the ground state and atom number density in the metastable 23S state. The results lay the ground for a comprehensive assessment of the efficiency of MEOP, by comparison with achievements at lower field (1 mT-2 T) over an extended range of operating conditions. Stronger hyperfine decoupling in the optically pumped 23S state is observed to systematically lead to slower build-up of 3He orientation in the ground state, as expected. The nuclear polarizations obtained at 4.7 T still decrease at high pressure but in a less dramatic way than observed at 2 T in the same sealed glass cells. To date, thanks to the linear increase in gas density, they correspond to the highest nuclear magnetizations achieved by MEOP in pure 3He gas. The improved efficiency puts less demanding requirements for compression stages in polarized gas production systems and makes high-field MEOP particularly attractive for magnetic resonance imaging of the lungs, for instance.

  5. Magnetostriction and magnetic texture to 100.75 Tesla in frustrated SrCu2(BO3)2

    PubMed Central

    Jaime, Marcelo; Daou, Ramzy; Crooker, Scott A.; Weickert, Franziska; Uchida, Atsuko; Feiguin, Adrian E.; Batista, Cristian D.; Dabkowska, Hanna A.; Gaulin, Bruce D.

    2012-01-01

    Strong geometrical frustration in magnets leads to exotic states such as spin liquids, spin supersolids, and complex magnetic textures. SrCu2(BO3)2, a spin-1/2 Heisenberg antiferromagnet in the archetypical Shastry–Sutherland lattice, exhibits a rich spectrum of magnetization plateaus and stripe-like magnetic textures in applied fields. The structure of these plateaus is still highly controversial due to the intrinsic complexity associated with frustration and competing length scales. We discover magnetic textures in SrCu2(BO3)2 via magnetostriction and magnetocaloric measurements in fields up to 100.75 T. In addition to observing low-field fine structure with unprecedented resolution, the data also reveal lattice responses at 73.6 T and at 82 T that we attribute, using a controlled density matrix renormalization group approach, to a unanticipated 2/5 plateau and to the long-predicted 1/2 plateau.

  6. A high resolution 7-Tesla resting-state fMRI test-retest dataset with cognitive and physiological measures

    PubMed Central

    Gorgolewski, Krzysztof J; Mendes, Natacha; Wilfling, Domenica; Wladimirow, Elisabeth; Gauthier, Claudine J; Bonnen, Tyler; Ruby, Florence J.M; Trampel, Robert; Bazin, Pierre-Louis; Cozatl, Roberto; Smallwood, Jonathan; Margulies, Daniel S

    2015-01-01

    Here we present a test-retest dataset of functional magnetic resonance imaging (fMRI) data acquired at rest. 22 participants were scanned during two sessions spaced one week apart. Each session includes two 1.5 mm isotropic whole-brain scans and one 0.75 mm isotropic scan of the prefrontal cortex, giving a total of six time-points. Additionally, the dataset includes measures of mood, sustained attention, blood pressure, respiration, pulse, and the content of self-generated thoughts (mind wandering). This data enables the investigation of sources of both intra- and inter-session variability not only limited to physiological changes, but also including alterations in cognitive and affective states, at high spatial resolution. The dataset is accompanied by a detailed experimental protocol and source code of all stimuli used. PMID:25977805

  7. Parceling of mesial frontal motor areas during ideation and movement using functional magnetic resonance imaging at 1.5 tesla.

    PubMed

    Tyszka, J M; Grafton, S T; Chew, W; Woods, R P; Colletti, P M

    1994-06-01

    Finger movement-related responses were identified in three discrete sites of mesial frontal cortex in 7 normal subjects using high resolution functional magnetic resonance imaging. During imagination of the same movements there was a differential response with rostral areas more active than caudal areas. Humans have multiple motor areas in mesial frontal cortex that subserve different functions in motor planning and execution.

  8. Anatomical and functional brain imaging using high-resolution echo-planar spectroscopic imaging at 1.5 Tesla.

    PubMed

    Du, Weiliang; Karczmar, Gregory S; Uftring, Stephen J; Du, Yiping P

    2005-06-01

    High-resolution echo-planar spectroscopic imaging (EPSI) of water resonance (i.e. without water suppression) is proposed for anatomic and functional imaging of the human brain at 1.5 T. Water spectra with a resolution of 2.6 Hz and a bandwidth of 333 Hz were obtained in small voxels (1.7 x 1.7 x 3 mm3) across a single slice. Although water spectra appeared Lorentzian in most of the voxels in the brain, non-Lorentzian broadening of the water resonance was observed in voxels containing blood vessels. In functional experiments with a motor task, robust activation in motor cortices was observed in high-resolution T2* maps generated from the EPSI data. Shift of the water resonance frequency occurred during neuronal activation in motor cortices. The activation areas appeared to be more localized after excluding the voxels in which the lineshape of the water resonance had elevated T2* and became more non-Lorentzian during the motor task. These preliminary results suggest that high-resolution EPSI is a promising tool to study susceptibility-related effects, such as BOLD contrast, for improved anatomical and functional imaging of the brain.

  9. Somatotopic organization of the medial wall of the cerebral hemispheres: a 3 Tesla fMRI study.

    PubMed

    Mayer, A R; Zimbelman, J L; Watanabe, Y; Rao, S M

    2001-12-01

    Somatotopic organization of the human medial wall of the cerebral hemispheres was studied using functional MRI conducted at high field strength (3 T) with fine spatial resolution ( approximately 2 mm). Healthy subjects performed paced, repetitive movements of the fingers and toes. Within the supplementary motor area (SMA), two regions were identified: finger movements activated a region rostral and superior to that for toe movements. Two activation foci were also identified in the cingulate motor area: toe movements activated a region rostral and ventral to that activated by finger movements. All foci were located between the anterior and posterior commissures. Our results confirm previous human and non-human primate studies regarding the rostral-caudal organization of the SMA and CMA. The dorsal-ventral organization of the CMA, however, appears to be divergent from results derived from cortical stimulation studies conducted in non-human primates.

  10. Iron accumulation in deep cortical layers accounts for MRI signal abnormalities in ALS: correlating 7 tesla MRI and pathology.

    PubMed

    Kwan, Justin Y; Jeong, Suh Young; Van Gelderen, Peter; Deng, Han-Xiang; Quezado, Martha M; Danielian, Laura E; Butman, John A; Chen, Lingye; Bayat, Elham; Russell, James; Siddique, Teepu; Duyn, Jeff H; Rouault, Tracey A; Floeter, Mary Kay

    2012-01-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by cortical and spinal motor neuron dysfunction. Routine magnetic resonance imaging (MRI) studies have previously shown hypointense signal in the motor cortex on T(2)-weighted images in some ALS patients, however, the cause of this finding is unknown. To investigate the utility of this MR signal change as a marker of cortical motor neuron degeneration, signal abnormalities on 3T and 7T MR images of the brain were compared, and pathology was obtained in two ALS patients to determine the origin of the motor cortex hypointensity. Nineteen patients with clinically probable or definite ALS by El Escorial criteria and 19 healthy controls underwent 3T MRI. A 7T MRI scan was carried out on five ALS patients who had motor cortex hypointensity on the 3T FLAIR sequence and on three healthy controls. Postmortem 7T MRI of the brain was performed in one ALS patient and histological studies of the brains and spinal cords were obtained post-mortem in two patients. The motor cortex hypointensity on 3T FLAIR images was present in greater frequency in ALS patients. Increased hypointensity correlated with greater severity of upper motor neuron impairment. Analysis of 7T T(2)(*)-weighted gradient echo imaging localized the signal alteration to the deeper layers of the motor cortex in both ALS patients. Pathological studies showed increased iron accumulation in microglial cells in areas corresponding to the location of the signal changes on the 3T and 7T MRI of the motor cortex. These findings indicate that the motor cortex hypointensity on 3T MRI FLAIR images in ALS is due to increased iron accumulation by microglia.

  11. Reproducibility of tract-specific magnetization transfer and diffusion tensor imaging in the cervical spinal cord at 3 tesla.

    PubMed

    Smith, Seth A; Jones, Craig K; Gifford, Aliya; Belegu, Visar; Chodkowski, BettyAnn; Farrell, Jonathan A D; Landman, Bennett A; Reich, Daniel S; Calabresi, Peter A; McDonald, John W; van Zijl, Peter C M

    2010-02-01

    Damage to specific white matter tracts within the spinal cord can often result in the particular neurological syndromes that characterize myelopathies such as traumatic spinal cord injury. Noninvasive visualization of these tracts with imaging techniques that are sensitive to microstructural integrity is an important clinical goal. Diffusion tensor imaging (DTI)- and magnetization transfer (MT)-derived quantities have shown promise in assessing tissue health in the central nervous system. In this paper, we demonstrate that DTI of the cervical spinal cord can reliably discriminate sensory (dorsal) and motor (lateral) columns. From data derived from nine healthy volunteers, two raters quantified column-specific parallel (lambda(||)) and perpendicular (lambda(perpendicular)) diffusivity, fractional anisotropy (FA), mean diffusivity (MD), and MT-weighted signal intensity relative to cerebrospinal fluid (MTCSF) over two time-points separated by more than 1 week. Cross-sectional means and standard deviations of these measures in the lateral and dorsal columns were as follows: lambda(||): 2.13 +/- 0.14 and 2.14 +/- 0.11 microm(2)/ms; lambda(perpendicular): 0.67 +/- 0.16 and 0.61 +/- 0.09 microm(2)/ms; MD: 1.15 +/- 0.15 and 1.12 +/- 0.08 microm(2)/ms; FA: 0.68 +/- 0.06 and 0.68 +/- 0.05; MTCSF: 0.52 +/- 0.05 and 0.50 +/- 0.05. We examined the variability and interrater and test-retest reliability for each metric. These column-specific MR measurements are expected to enhance understanding of the intimate structure-function relationship in the cervical spinal cord and may be useful for the assessment of disease progression.

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

    PubMed

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

    2015-01-01

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

  13. Proton echo-planar spectroscopic imaging of J-coupled resonances in human brain at 3 and 4 Tesla.

    PubMed

    Posse, Stefan; Otazo, Ricardo; Caprihan, Arvind; Bustillo, Juan; Chen, Hongji; Henry, Pierre-Gilles; Marjanska, Malgorzata; Gasparovic, Charles; Zuo, Chun; Magnotta, Vincent; Mueller, Bryon; Mullins, Paul; Renshaw, Perry; Ugurbil, Kamil; Lim, Kelvin O; Alger, Jeffry R

    2007-08-01

    In this multicenter study, 2D spatial mapping of J-coupled resonances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-suppressed (WS) data were acquired in 8.5 min with 1-cm(3) spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral fitting in reference to a non-WS (NWS) scan was performed with LCModel using correction for relaxation attenuation and partial-volume effects. The concentrations of total choline (tCho), creatine + phosphocreatine (Cr+PCr), glutamate (Glu), glutamate + glutamine (Glu+Gln), myo-inositol (Ins), NAA, NAA+NAAG, and two macromolecular resonances at 0.9 and 2.0 ppm were mapped with mean Cramer-Rao lower bounds (CRLBs) between 6% and 18% and approximately 150-cm(3) sensitive volumes. Aspartate, GABA, glutamine (Gln), glutathione (GSH), phosphoethanolamine (PE), and macromolecules (MMs) at 1.2 ppm were also mapped, although with larger mean CRLBs between 30% and 44%. The CRLBs at 4T were 19% lower on average as compared to 3T, consistent with a higher signal-to-noise ratio (SNR) and increased spectral resolution. Metabolite concentrations were in the ranges reported in previous studies. Glu concentration was significantly higher in gray matter (GM) compared to white matter (WM), as anticipated. The short acquisition time makes this methodology suitable for clinical studies. PMID:17610279

  14. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla

    DOE PAGES

    Stier, Andreas V.; McCreary, Kathleen M.; Jonker, Berend T.; Kono, Junichiro; Crooker, Scott A.

    2016-02-09

    In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately –230 μeV T–1 (g-factor ≃–4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radiimore » of ~1.53 and ~1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). Lastly, these results highlight the utility of high magnetic fields for understanding new two-dimensional materials.« less

  15. The Role of Apparent Diffusion Coefficient Quantification in Differentiating Benign and Malignant Renal Masses by 3 Tesla Magnetic Resonance Imaging

    PubMed Central

    Göya, Cemil; Hamidi, Cihad; Bozkurt, Yaşar; Yavuz, Alpaslan; Kuday, Suzan; Gümüş, Hatice; Türkçü, Gül; Hattapoğlu, Salih; Bilici, Aslan

    2015-01-01

    Background: Diffusion-weighted magnetic resonance imaging (DWI) is a widely-accepted diagnostic modality whose efficacy has been investigated by numerous past studies in the differentiation of malignant lesions from benign entities. Aims: The aim of this study was to evaluate the efficiency of diffusion-weighted magnetic resonance imaging in the characterization of renal lesions. Study Design: Diagnostic accuracy study. Methods: A total of 137 patients with renal lesions were included in this study. The median apparent diffusion coefficient (ADC) values as well as the b 800 and b 1600 signal intensities of normal kidneys, solid components of mixed renal masses, and total cystic lesions were evaluated. Results: There were significant differences between the ADC values of lesions and normal renal parenchyma, and between the ADC values of benign and malignant renal lesions on DWIs at b values of 800 and 1600 s/mm2 (p<0.001 and p<0.001, respectively). There were significant differences between the ADC values of Bosniak Category 1 and 2 cysts and the ADC values of Bosniak Category 1 and 3 cysts on DWIs at b values of 800 s/mm2 (p<0.001) and 1600 s/mm2 (p<0.001). A cutoff value of 1.902 × 10−3 mm2/s for the ADC with a b value of 800 s/mm2 provided 88% sensitivity and 96% specificity for differentiation between benign and malignant renal lesions. A cutoff value of 1.623 × 10−3 mm2/s for the ADC with a b value of 1600 s/mm2 provided 79% sensitivity and 96% specificity (p<0.001) for the differentiation between benign and malignant renal lesions. Conclusion: Accurate assessment of renal masses is important for determining the necessity for surgical intervention. DWI provides additional value by differentiating benign from malignant renal tumors and can be added to routine kidney MRI protocols. PMID:26185715

  16. Cognitive effects of head-movements in stray fields generated by a 7 Tesla whole-body MRI magnet.

    PubMed

    de Vocht, F; Stevens, T; Glover, P; Sunderland, A; Gowland, P; Kromhout, H

    2007-05-01

    The study investigates the impact of exposure to the stray magnetic field of a whole-body 7 T MRI scanner on neurobehavioral performance and cognition. Twenty seven volunteers completed four sessions, which exposed them to approximately 1600 mT (twice), 800 mT and negligible static field exposure. The order of exposure was assigned at random and was masked by placing volunteers in a tent to hide their position relative to the magnet bore. Volunteers completed a test battery assessing auditory working memory, eye-hand co-ordination, and visual perception. During three sessions the volunteers were instructed to complete a series of standardized head movements to generate additional time-varying fields ( approximately 300 and approximately 150 mT.s(-1) r.m.s.). In one session, volunteers were instructed to keep their heads as stable as possible. Performance on a visual tracking task was negatively influenced (P<.01) by 1.3% per 100 mT exposure. Furthermore, there was a trend for performance on two cognitive-motor tests to be decreased (P<.10). No effects were observed on working memory. Taken together with results of earlier studies, these results suggest that there are effects on visual perception and hand-eye co-ordination, but these are weak and variable between studies. The magnitude of these effects may depend on the magnitude of time-varying fields and not so much on the static field. While this study did not include exposure above 1.6 T, it suggests that use of strong magnetic fields is not a significant confounder in fMRI studies of cognitive function. Future work should further assess whether ultra-high field may impair performance of employees working in the vicinity of these magnets.

  17. A 2 Tesla Full Scale High Performance Periodic Permanent Magnet Model for Attractive (228 KN) and repulsive Maglev

    NASA Technical Reports Server (NTRS)

    Stekly, Z. J. J.; Gardner, C.; Domigan, P.; Baker, J.; Hass, M.; McDonald, C.; Wu, C.; Farrell, R. A.

    1996-01-01

    Two 214.5 cm. long high performance periodic (26 cm period) permanent magnet half-assemblies were designed and constructed for use as a wiggler using Nd-B-Fe and vanadium permendur as hard and soft magnetic materials by Field Effects, a division of Intermagnetics General Corporation. Placing these assemblies in a supporting structure with a 2.1 cm pole to pole separation resulted in a periodic field with a maximum value of 2.04 T. This is believed to be the highest field ever achieved by this type of device. The attractive force between the two 602 kg magnet assemblies is 228 kN, providing enough force for suspension of a 45,500 kg vehicle. If used in an attractive maglev system with an appropriate flat iron rail, one assembly will generate the same force with a gap of 1.05 cm leading to a lift to weight ratio of 38.6, not including the vehicle attachment structure. This permanent magnet compares well with superconducting systems which have lift to weight ratios in the range of 5 to 10. This paper describes the magnet assemblies and their measured magnetic performance. The measured magnetic field and resulting attractive magnetic force have a negative spring characteristic. Appropriate control coils are necessary to provide stable operation. The estimated performance of the assemblies in a stable repulsive mode, with eddy currents in a conducting guideway, is also discussed.

  18. Magneto-oscillations in BEDT-TTF salts in Pulsed Magnetic Fields of up to 55 Tesla

    NASA Astrophysics Data System (ADS)

    Singleton, John

    1997-03-01

    Charge-transfer salts based on the molecule BEDT-TTF are excellent systems for high-magnetic-field studies of novel fermiological and many-body effects (G. Boebinger, Physics Today, June 1996, p36). The salts have quasi-two-dimensional Fermi surfaces, and exhibit a wide variety of low temperature groundstates; high quality crystals are available, so that phenomena such as cyclotron resonance and the de Haas-van Alphen effect may be readily observed (J. Singleton et al., Surface Science 361), 894 (1996). This presentation will report magnetisation measurements of the salts carried out in pulsed magnetic fields of up to 55 T and at temperatures down to 350 mK. These experiments reveal very strong quantum oscillations consisting of two components, de Haas-van Alphen oscillations and so-called ``eddy current resonances'', caused by the very deep minima in the resistivity which accompany the quantum Hall effect (N. Harrison et al., Phys. Rev. Lett. 77), 1576 (1996). The magnetisation studies are discussed in the context of numerical models of the magnetisation and magnetoresistance of BEDT-TTF salts (N. Harrison et al., Phys. Rev. B 54), 9977 (1996). It is found that the quantum Hall effect should indeed be present at high magnetic fields in such materials, in spite of the coexistence of quasi-one and quasi-two-dimensional Fermi surface components. Recent attempts to observe quantum Hall plateaux in magnetotransport experiments by the author and coworkers will be reviewed and evidence for the field-induced localisation of one-dimensional electrons in BEDT-TTF salts will be discussed.

  19. [Imaging anatomy of the cranial nerves using 3.0 Tesla MRI: a practical review for clinicians].

    PubMed

    Chávez-Barba, Oscar; Martínez-Martínez, Lidieth; Cazares-Arellano, José Luis; Martínez-López, Manuel; Roldan-Valadez, Ernesto

    2011-01-01

    Magnetic resonance (MR) imaging is the method of choice to evaluate the cranial nerves (CN). These nerves constitute a group of structures that have acquired during their phylogenetic development a high degree of specialization. There are 12 pairs of CN to which we use their specific name or number. The olfactory (I) and optic (II) pairs are not real nerves but tracts from the encephalon. The spinal nerve (XI) derives from superior cervical segment of the spine. The other 9 pairs of CN are related with the brain stem. Although the skull base foramina can be seen on computed tomography, the nerves themselves can only be visualized in detail on MR. That means, in order to see the different segments of nerves I to XII, the right sequences must be used. It is important to provide detailed clinical information to the radiologist so that a tailored MR study can be performed. In this review, the basic imaging anatomy of the 12 CN is discussed and illustrated briefly with an emphasis on more advanced extra-axial anatomy, illustrated with high-resolution MR images. Clinicians looking for complete anatomic descriptions and/or MR illustrations are advised to consult specialized textbooks considering it is not possible to describe all of the anatomy in one article. This manuscript is intended to be a practical review for clinicians.

  20. Investigation of the Saturation Pulse Artifact in Non-Enhanced MR Angiography of the Lower Extremity Arteries at 7 Tesla

    PubMed Central

    Johst, Sören; Maderwald, Stefan; Fischer, Anja; Quick, Harald H.; Ladd, Mark E.; Orzada, Stephan

    2015-01-01

    When performing non-enhanced time-of-flight MR angiography of the lower extremity arteries at 7 T with cardiac triggering, the acquisition time is a crucial consideration. Therefore, in previous studies, saturation RF pulses were applied only every second TR. In the axial source images a slight artifact with an appearance similar to aliasing could be observed. The purpose of this study was to investigate the origin of this artifact. The reason for the artifact is supposed to be related to the two effective TRs during acquisition caused by the sparsely applied saturation RF pulse. Several sequence variants were simulated and implemented within the sequence source code to examine this hypothesis. An adaptation of the excitation flip angles for each TR as well as a correction factor for the k-space data was calculated. Additionally, a different ordering of the k-space data during acquisition was implemented as well as the combination of the latter with the k-space correction factor. The observations from the simulations were verified using both a static and a flow phantom and, finally, in a healthy volunteer using the same measurement setup as in previous volunteer and patient studies. Of all implemented techniques, only the reordering of the k-space was capable of suppressing the artifact almost completely at the cost of creating a ringing artifact. The phantom measurements showed the same results as the simulations and could thus confirm the hypothesis regarding the origin of the artifact. This was additionally verified in the healthy volunteer. The origin of the artifact could be confirmed to be the periodic signal variation caused by two effective TRs during acquisition. PMID:25785837

  1. Quantitative assessment of cerebral hemodynamic parameters by QUASAR arterial spin labeling in Alzheimer's disease and cognitively normal Elderly adults at 3-tesla.

    PubMed

    Mak, Henry K F; Chan, Queenie; Zhang, Zhipeng; Petersen, Esben T; Qiu, Deqiang; Zhang, Linda; Yau, Kelvin K W; Chu, Leung-Wing; Golay, Xavier

    2012-01-01

    QUASAR arterial spin labeling (ASL) was used to investigate the role of vascular impairment in Alzheimer's disease (AD). We hypothesized that the hemodynamic parameters monitoring cerebrovascular integrity, i.e., cerebral blood flow (CBF), arterial blood volume (aBV), and arterial transit time (aTT), would be affected. 13 AD patients and 15 healthy control (HC) subjects underwent 3T MRI scanning. Two separate blood flow acquisitions were obtained with 1 slice overlap for whole brain coverage. CBF, aBV, and aTT maps were calculated using in-house software. Preprocessing and statistical analyses were performed on SPM5. Region-of-interest (ROI) studies of ten selected cerebral regions were also conducted. There were significant differences in mini mental status exam (MMSE) (AD: 16.3 ± 4.55, HC: 28.5 ± 2.00) and Alzheimer's disease assessment scale-cognitive subscale (ADAS-cog) scores (AD: 25.25 ± 9.64, HC: 5.51 ± 2.62) between the 2 groups (p < 0.001) but none in age (p = 0.068). CBF decreased significantly (p < 0.01) in AD compared to controls in the right middle cingulate, left cuneus, left inferior and middle frontal, right superior frontal, left inferior parietal, and right supramarginal gyri. ROI studies confirmed significant hemodynamic impairments in AD compared to HC (p < 0.05): CBF in middle and posterior cingulate, aBV in left superior temporal, right inferior parietal, and posterior cingulate, and aTT in left inferior frontal and middle cingulate gyri. CBF correlated positively while aTT correlated negatively to MMSE, and vice versa for ADAS-cog. Using QUASAR ASL, we found patterns of regional hemodynamic impairment typical of moderate AD, suggesting underlying vascular abnormality. As potential biomarkers, these hemodynamic parameters could differentiate patients from volunteers, and possibly indicate the conversion from healthy aging to mild cognitive impairment to AD.

  2. Regional in vivo transit time measurements of aortic pulse wave velocity in mice with high-field CMR at 17.6 Tesla

    PubMed Central

    2010-01-01

    Background Transgenic mouse models are increasingly used to study the pathophysiology of human cardiovascular diseases. The aortic pulse wave velocity (PWV) is an indirect measure for vascular stiffness and a marker for cardiovascular risk. Results This study presents a cardiovascular magnetic resonance (CMR) transit time (TT) method that allows the determination of the PWV in the descending murine aorta by analyzing blood flow waveforms. Systolic flow pulses were recorded with a temporal resolution of 1 ms applying phase velocity encoding. In a first step, the CMR method was validated by pressure waveform measurements on a pulsatile elastic vessel phantom. In a second step, the CMR method was applied to measure PWVs in a group of five eight-month-old apolipoprotein E deficient (ApoE(-/-)) mice and an age matched group of four C57Bl/6J mice. The ApoE(-/-) group had a higher mean PWV (PWV = 3.0 ± 0.6 m/s) than the C57Bl/6J group (PWV = 2.4 ± 0.4 m/s). The difference was statistically significant (p = 0.014). Conclusions The findings of this study demonstrate that high field CMR is applicable to non-invasively determine and distinguish PWVs in the arterial system of healthy and diseased groups of mice. PMID:21134260

  3. Pulsed-coil magnet systems for applying 10-30 Tesla Fields to cm-scale targets on Sandia's Z facility

    DOE PAGES

    Rovang, Dean C.; Lamppa, Derek C.; Cuneo, Michael Edward; Owen, Albert; Mckenney, John; Johnson, Drew; Radovich, Shawn; Kaye, Ronald J.; McBride, Ryan D; Alexander, C. Scott; et al

    2014-12-04

    We have successfully integrated the capability to apply uniform, high magnetic fields (10–30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1–3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2–7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnosticmore » lines of sight to the target. We then describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.« less

  4. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla

    PubMed Central

    Stier, Andreas V.; McCreary, Kathleen M.; Jonker, Berend T.; Kono, Junichiro; Crooker, Scott A.

    2016-01-01

    In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately −230 μeV T−1 (g-factor ≃−4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radii of ∼1.53 and ∼1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). These results highlight the utility of high magnetic fields for understanding new two-dimensional materials. PMID:26856412

  5. Integrating structural and functional imaging for computer assisted detection of prostate cancer on multi-protocol in vivo 3 Tesla MRI

    NASA Astrophysics Data System (ADS)

    Viswanath, Satish; Bloch, B. Nicolas; Rosen, Mark; Chappelow, Jonathan; Toth, Robert; Rofsky, Neil; Lenkinski, Robert; Genega, Elizabeth; Kalyanpur, Arjun; Madabhushi, Anant

    2009-02-01

    Screening and detection of prostate cancer (CaP) currently lacks an image-based protocol which is reflected in the high false negative rates currently associated with blinded sextant biopsies. Multi-protocol magnetic resonance imaging (MRI) offers high resolution functional and structural data about internal body structures (such as the prostate). In this paper we present a novel comprehensive computer-aided scheme for CaP detection from high resolution in vivo multi-protocol MRI by integrating functional and structural information obtained via dynamic-contrast enhanced (DCE) and T2-weighted (T2-w) MRI, respectively. Our scheme is fully-automated and comprises (a) prostate segmentation, (b) multimodal image registration, and (c) data representation and multi-classifier modules for information fusion. Following prostate boundary segmentation via an improved active shape model, the DCE/T2-w protocols and the T2-w/ex vivo histological prostatectomy specimens are brought into alignment via a deformable, multi-attribute registration scheme. T2-w/histology alignment allows for the mapping of true CaP extent onto the in vivo MRI, which is used for training and evaluation of a multi-protocol MRI CaP classifier. The meta-classifier used is a random forest constructed by bagging multiple decision tree classifiers, each trained individually on T2-w structural, textural and DCE functional attributes. 3-fold classifier cross validation was performed using a set of 18 images derived from 6 patient datasets on a per-pixel basis. Our results show that the results of CaP detection obtained from integration of T2-w structural textural data and DCE functional data (area under the ROC curve of 0.815) significantly outperforms detection based on either of the individual modalities (0.704 (T2-w) and 0.682 (DCE)). It was also found that a meta-classifier trained directly on integrated T2-w and DCE data (data-level integration) significantly outperformed a decision-level meta-classifier, constructed by combining the classifier outputs from the individual T2-w and DCE channels.

  6. Reproducibility of Kidney Perfusion Measurements With Arterial Spin Labeling at 1.5 Tesla MRI Combined With Semiautomatic Segmentation for Differential Cortical and Medullary Assessment

    PubMed Central

    Hammon, Matthias; Janka, Rolf; Siegl, Christian; Seuss, Hannes; Grosso, Roberto; Martirosian, Petros; Schmieder, Roland E.; Uder, Michael; Kistner, Iris

    2016-01-01

    Abstract Magnetic resonance imaging with arterial spin labeling (ASL) is a noninvasive approach to measure organ perfusion. The purpose of this study was to evaluate the reproducibility of ASL kidney perfusion measurements with semiautomatic segmentation, which allows separate quantification of cortical and medullary perfusion. The right kidneys of 14 healthy volunteers were examined 6 times on 2 occasions (3 times at each occasion). There was a 10-minute pause between each examination and a 14-day interval between the 2 occasions. Cortical, medullary, and whole kidney parenchymal perfusion was determined with customized semiautomatic segmentation software. Coefficient of variances (CVs) and intraclass correlations (ICCs) were calculated. Mean whole, cortical, and medullary kidney perfusion was 307.26 ± 25.65, 337.10 ± 34.83, and 279.61 ± 26.73 mL/min/100 g, respectively. On session 1, mean perfusion for the whole kidney, cortex, and medulla was 307.08 ± 26.91, 336.79 ± 36.54, and 279.60 ± 27.81 mL/min/100 g, respectively, and on session 2, 307.45 ± 24.65, 337.41 ± 33.48, and 279.61 ± 25.94 mL/min/100 g, respectively (P > 0.05; R2 = 0.60/0.59/0.54). For whole, cortical, and medullary kidney perfusion, the total ICC/CV were 0.97/3.43 ± 0.86%, 0.97/4.19 ± 1.33%, and 0.96/4.12 ± 1.36%, respectively. Measurements did not differ significantly and showed a very good correlation (P > 0.05; R2 = 0.75/0.76/0.65). ASL kidney measurements combined with operator-independent semiautomatic segmentation revealed high correlation and low variance of cortical, medullary, and whole kidney perfusion. PMID:26986143

  7. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla.

    PubMed

    Stier, Andreas V; McCreary, Kathleen M; Jonker, Berend T; Kono, Junichiro; Crooker, Scott A

    2016-01-01

    In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately -230 μeV T(-1) (g-factor ≃-4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radii of ∼1.53 and ∼1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). These results highlight the utility of high magnetic fields for understanding new two-dimensional materials. PMID:26856412

  8. Bias in Estimation of Hippocampal Atrophy using Deformation-Based Morphometry Arises from Asymmetric Global Normalization: An Illustration in ADNI 3 Tesla MRI Data

    PubMed Central

    Yushkevich, Paul A.; Avants, Brian B.; Das, Sandhitsu R.; Pluta, John; Altinay, Murat; Craige, Caryne

    2009-01-01

    Measurement of brain change due to neurodegenerative disease and treatment is one of the fundamental tasks of neuroimaging. Deformation-based morphometry (DBM) has been long recognized as an effective and sensitive tool for estimating the change in the volume of brain regions over time. This paper demonstrates that a straightforward application of DBM to estimate the change in the volume of the hippocampus can result in substantial bias, i.e., an overestimation of the rate of change in hippocampal volume. In ADNI data, this bias is manifested as a non-zero intercept of the regression line fitted to the 6 and 12 month rates of hippocampal atrophy. The bias is further confirmed by applying DBM to repeat scans of subjects acquired on the same day. This bias appears to be the result of asymmetry in the interpolation of baseline and followup images during longitudinal image registration. Correcting this asymmetry leads to bias-free atrophy estimation. PMID:20005963

  9. Integrated RF probe for in vivo multinuclear spectroscopy and functional imaging of rat brain using an 11.7 Tesla 89 mm bore vertical microimager.

    PubMed

    Li, S; Shen, J

    2005-07-01

    To acquire high quality in vivo NMR data from rat brain using a vertical 89-mm bore magnet, specially designed NMR probes with integrated RF coils and animal handling capability are required. An RF probe design that is also capable of rat head fixation, body support and suitable for physiology monitoring and maintenance was constructed for an 89 mm bore, 11.7 T, vertical microimager which is equipped with a 57-mm i.d. gradient insert. Design concept and practical aspects of probe construction are described in detail. The device allows accurate and highly reproducible positioning of rat head inside the magnet while providing excellent RF performance. Typical results from fMRI, localized in vivo proton and multinuclear spectroscopy using this probe system are presented. PMID:16007474

  10. In vivo magnetic resonance imaging at 11.7 Tesla visualized the effects of neonatal transection of infraorbital nerve upon primary and secondary trigeminal pathways in rats.

    PubMed

    Ooi, Yasuhiro; Inui-Yamamoto, Chizuko; Suzuki, Takashi; Nakadate, Hiromichi; Nagase, Yoshitaka; Seiyama, Akitoshi; Yoshioka, Yoshichika; Seki, Junji

    2014-09-01

    Using 11.7T ultra high-field T2-weighted MRI, the present study aimed to investigate pathological changes of primary and secondary trigeminal pathways following neonatal transection of infraorbital nerve in rats. The trigeminal pathways consist of spinal trigeminal tract, trigeminal sensory nuclear complex, medial lemniscus, ventromedial portion of external medullary lamina and ventral posterior nucleus of thalamus. By selecting optimum parameters of MRI such as repetition time, echo time, and slice orientation, this study visualized the trigeminal pathways in rats without any contrast agents. Pathological changes due to the nerve transection were found at 8 weeks of age as a marked reduction of the areas of the trigeminal pathways connecting from the injured nerve. In addition, T2-weighted MR images of the trigeminal nerve trunk and the spinal trigeminal tract suggest a communication of CSF through the trigeminal nerve between the inside and outside of the brain stem. These results support the utility of ultra high-field MRI system for noninvasive assessment of effects of trigeminal nerve injury upon the trigeminal pathways.

  11. Matching field effects at tesla-level magnetic fields in critical current density in high-Tc superconductors containing self-assembled columnar defects

    SciTech Connect

    Sinclair, J.; Zuev, Yuri L; Cantoni, Claudia; Wee, Sung Hun; Varanasi, C. V.; Thompson, James R; Christen, David K

    2012-01-01

    We have investigated the superconductive transport properties of YBa2Cu3O7 films containing self-assembled columnar arrays of second phase SrZrO3 or BaSnO3 precipitates. A matching condition between columnar pinning sites (aligned at or near the c axis) and external magnetic flux, tilted with respect to them, is identified in the critical current JC.H/ data. The results for the material containing SrZrO3-based pins are analyzed within a simple intuitive model. At matching, the critical current is enhanced above the model prediction. In complementary contact-free investigations of BaSnO3-doped material, matching effects are observed over a wide range of temperatures in the field dependence of JC.H/. The deduced matching fields agree reasonably well with the densities of columnar pins directly observed by scanning electron microscopy.

  12. 3-Dimensional Magnetic Resonance Spectroscopic Imaging at 3 Tesla for Early Response Assessment of Glioblastoma Patients During External Beam Radiation Therapy

    SciTech Connect

    Muruganandham, Manickam; Clerkin, Patrick P.; Smith, Brian J.; Anderson, Carryn M.; Morris, Ann; Capizzano, Aristides A.; Magnotta, Vincent; McGuire, Sarah M.; Smith, Mark C.; Bayouth, John E.; Buatti, John M.

    2014-09-01

    Purpose: To evaluate the utility of 3-dimensional magnetic resonance (3D-MR) proton spectroscopic imaging for treatment planning and its implications for early response assessment in glioblastoma multiforme. Methods and Materials: Eighteen patients with newly diagnosed, histologically confirmed glioblastoma had 3D-MR proton spectroscopic imaging (MRSI) along with T2 and T1 gadolinium-enhanced MR images at simulation and at boost treatment planning after 17 to 20 fractions of radiation therapy. All patients received standard radiation therapy (RT) with concurrent temozolomide followed by adjuvant temozolomide. Imaging for response assessment consisted of MR scans every 2 months. Progression-free survival was defined by the criteria of MacDonald et al. MRSI images obtained at initial simulation were analyzed for choline/N-acetylaspartate ratios (Cho/NAA) on a voxel-by-voxel basis with abnormal activity defined as Cho/NAA ≥2. These images were compared on anatomically matched MRSI data collected after 3 weeks of RT. Changes in Cho/NAA between pretherapy and third-week RT scans were tested using Wilcoxon matched-pairs signed rank tests and correlated with progression-free survival, radiation dose and location of recurrence using Cox proportional hazards regression. Results: After a median follow-up time of 8.6 months, 50% of patients had experienced progression based on imaging. Patients with a decreased or stable mean or median Cho/NAA values had less risk of progression (P<.01). Patients with an increase in mean or median Cho/NAA values at the third-week RT scan had a significantly greater chance of early progression (P<.01). An increased Cho/NAA at the third-week MRSI scan carried a hazard ratio of 2.72 (95% confidence interval, 1.10-6.71; P=.03). Most patients received the prescription dose of RT to the Cho/NAA ≥2 volume, where recurrence most often occurred. Conclusion: Change in mean and median Cho/NAA detected at 3 weeks was a significant predictor of early progression. The potential impact for risk-adaptive therapy based on early spectroscopic findings is suggested.

  13. Pulsed-coil magnet systems for applying 10-30 Tesla Fields to cm-scale targets on Sandia's Z facility

    SciTech Connect

    Rovang, Dean C.; Lamppa, Derek C.; Cuneo, Michael Edward; Owen, Albert; Mckenney, John; Johnson, Drew; Radovich, Shawn; Kaye, Ronald J.; McBride, Ryan D; Alexander, C. Scott; Awe, Thomas James; Slutz, Stephen A.; Sefkow, Adam B; Haill, Thomas A.; Jones, Peter Andrew; Argo, Jeffrey W; Dalton, Devon; Robertson, Grafton Kincannon; Waisman, Eduardo Mario; Sinars, Daniel Brian; Meissner, Joel; Milhous, Mark; Nguyen, Doan; Mielke, Chuck

    2014-12-04

    We have successfully integrated the capability to apply uniform, high magnetic fields (10–30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1–3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2–7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We then describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

  14. In vivo magnetic resonance imaging at 11.7 Tesla visualized the effects of neonatal transection of infraorbital nerve upon primary and secondary trigeminal pathways in rats.

    PubMed

    Ooi, Yasuhiro; Inui-Yamamoto, Chizuko; Suzuki, Takashi; Nakadate, Hiromichi; Nagase, Yoshitaka; Seiyama, Akitoshi; Yoshioka, Yoshichika; Seki, Junji

    2014-09-01

    Using 11.7T ultra high-field T2-weighted MRI, the present study aimed to investigate pathological changes of primary and secondary trigeminal pathways following neonatal transection of infraorbital nerve in rats. The trigeminal pathways consist of spinal trigeminal tract, trigeminal sensory nuclear complex, medial lemniscus, ventromedial portion of external medullary lamina and ventral posterior nucleus of thalamus. By selecting optimum parameters of MRI such as repetition time, echo time, and slice orientation, this study visualized the trigeminal pathways in rats without any contrast agents. Pathological changes due to the nerve transection were found at 8 weeks of age as a marked reduction of the areas of the trigeminal pathways connecting from the injured nerve. In addition, T2-weighted MR images of the trigeminal nerve trunk and the spinal trigeminal tract suggest a communication of CSF through the trigeminal nerve between the inside and outside of the brain stem. These results support the utility of ultra high-field MRI system for noninvasive assessment of effects of trigeminal nerve injury upon the trigeminal pathways. PMID:25038563

  15. Development of a nano-tesla magnetic field shielded chamber and highly precise AC-susceptibility measurement coil at μK temperatures

    NASA Astrophysics Data System (ADS)

    Kumar, Anil; Prakash, Om; Ramakrishanan, S.

    2014-04-01

    A special sample measurement chamber has been developed to perform experiments at ultralow temperatures and ultralow magnetic field. A high permeability material known as cryoperm 10 and Pb is used to shield the measurement space consisting of the signal detecting set-up and the sample. The detecting setup consists of a very sensitive susceptibility coil wound on OFHC Cu bobbin.

  16. Sodium-23 MRI of whole spine at 3 Tesla using a 5-channel receive-only phased-array and a whole-body transmit resonator.

    PubMed

    Malzacher, Matthias; Kalayciyan, Raffi; Konstandin, Simon; Haneder, Stefan; Schad, Lothar R

    2016-03-01

    Sodium magnetic resonance imaging ((23)Na MRI) is a unique and non-invasive imaging technique which provides important information on cellular level about the tissue of the human body. Several applications for (23)Na MRI were investigated with regard to the examination of the tissue viability and functionality for example in the brain, the heart or the breast. The (23)Na MRI technique can also be integrated as a potential monitoring instrument after radiotherapy or chemotherapy. The main contribution in this work was the adaptation of (23)Na MRI for spine imaging, which can provide essential information on the integrity of the intervertebral disks with respect to the early detection of disk degeneration. In this work, a transmit-only receive-only dual resonator system was designed and developed to cover the whole human spine using (23)Na MRI and increase the receive sensitivity. The resonator system consisted of an already presented (23)Na whole-body resonator and a newly developed 5-channel receive-only phased-array. The resonator system was first validated using bench top and phantom measurements. A threefold SNR improvement at the depth of the spine (∼7cm) over the whole-body resonator was achieved using the spine array. (23)Na MR measurements of the human spine using the transmit-only receive-only resonator system were performed on a healthy volunteer within an acquisition time of 10minutes. A density adapted 3D radial sequence was chosen with 6mm isotropic resolution, 49ms repetition time and a short echo time of 540μs. Furthermore, it was possible to quantify the tissue sodium concentration in the intervertebral discs in the lumbar region (120ms repetition time) using this setup. PMID:25891846

  17. A 5.9 tesla conduction-cooled coil composed of a stack of four single pancakes wound with YBCO wide tapes

    NASA Astrophysics Data System (ADS)

    Iwai, Sadanori; Miyazaki, Hiroshi; Tosaka, Taizo; Tasaki, Kenji; Urata, Masami; Ioka, Shigeru; Ishii, Yusuke

    2013-11-01

    We have been developing a conduction-cooled coil wound with YBCO-coated conductors for HTS applications. Previously, we have fabricated a coil composed of a stack of 12 single pancakes wound with 4 mm-wide YBCO tapes. This coil had a central magnetic field as high as 5.1 T at 10 K under conduction-cooled conditions. In the present study, we fabricated and tested a coil composed of a stack of four single pancakes wound with 12 mm-wide YBCO tapes. The total size of the coil and the Jc value of the tapes were almost the same as those of the former coil. At 77 K, the voltage-current characteristics showed a high n-value of 24, confirming that the coil had no degradation. Furthermore, in a conduction-cooled configuration at 20 K to 60 K, the coil showed a high n-value of over 20. At 20 K, the central magnetic field reached 5.9 T at 903 A, which is 1.3-times higher than that of the former coil.

  18. 3.0 Tesla MRI in the early evaluation of inferior alveolar nerve neurological complications after mandibular third molar extraction: a prospective study

    PubMed Central

    Pranno, N; Barchetti, F; Sorrentino, V; Lo Mele, L

    2014-01-01

    Objectives: To evaluate the use of 3.0 T MRI in the prognosis of inferior alveolar nerve (IAN) sensory disorders after mandibular third molar extraction, in the early post-operative period. Methods: 343 IANs were examined before and 3 days after surgery. Two radiologists evaluated the course of the nerve and the relative signal intensity (RSI). Cohen's kappa coefficient (κ) and intraclass correlation coefficient (ICC) were used to evaluate the interobserver (k = 0.891) and intra-observer variability (ICC = 0.927; 0.914, respectively). The IANs were divided into four groups on the basis of neurosensory disorders recovery time. ANOVA was used to evaluate the differences among the RSIs of the four groups, and multiple comparisons were performed with Tukey's range test. Results: No differences in the course of IANs were found before and after surgery. In 280 IANs, no iatrogenic paraesthesia was found (Group A). 63 IANs showed a neurosensory impairment. 38 IANs showed recovery of post-operative paraesthesia at 3-month follow-up (Group B). 16 IANs showed a full recovery of iatrogenic paraesthesia at 6-month follow-up (Group C). Seven IANs displayed a full recovery at 12-month follow-up and two IANs showed persistence of neurosensory disorders at 18-month follow-up (Group D). The one-way ANOVA results indicated statistically significant difference among all groups (p < 0.05), except between Groups C and D (p = 0.504). Conclusions: The early evaluation of RSI values represents a valid tool to determine the prognosis of IAN sensory disorders after mandibular third molar extraction. PMID:24947977

  19. Dynamic Contrast-Enhanced MRI Parameters as Biomarkers in Assessing Head and Neck Lesions After Chemoradiotherapy Using a Wide-Bore 3 Tesla Scanner.

    PubMed

    Lerant, Gergely; Sarkozy, Peter; Takacsi-Nagy, Zoltan; Polony, Gabor; Tamas, Laszlo; Toth, Erika; Boer, Andras; Javor, Laszlo; Godeny, Maria

    2015-09-01

    Pilot studies have shown promising results in characterizing head and neck tumors (HNT) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), differentiating between malignant and benign lesions and evaluating changes in response to chemoradiotherapy (CRT). Our aim was to find DCE-MRI parameters, biomarkers in evaluating the post-CRT status. Two hundred and five patients with head and neck lesions were examined with DCE-MRI sequences. The time intensity curves (TIC) were extracted and processed to acquire time-to-peak (TTP), relative maximum enhancement (RME), relative wash-out (RWO), and two new parameters attack and decay. These parameters were analyzed using univariate tests in SPSS (Statistical Package for the Social Sciences, version 17, SPSS Inc. Chicago, USA) to identify parameters that could be used to infer tumor malignancy and post-CRT changes. Multiple parameters of curve characteristics were significantly different between malignant tumors after CRT (MACRT) and changes caused by CRT. The best-performing biomarkers were the attack and the decay. We also found multiple significant (p < 0.05) parameters for both the benign and malignant status as well as pre- and post-CRT status. Our large cohort of data supports the increasing role of DCE-MRI in HNT differentiation, particularly for the assessment of post-CRT status along with accurate morphological imaging. PMID:25920367

  20. Reproducibility and absolute quantification of muscle glycogen in patients with glycogen storage disease by 13C NMR spectroscopy at 7 Tesla.

    PubMed

    Heinicke, Katja; Dimitrov, Ivan E; Romain, Nadine; Cheshkov, Sergey; Ren, Jimin; Malloy, Craig R; Haller, Ronald G

    2014-01-01

    Carbon-13 magnetic resonance spectroscopy (13C MRS) offers a noninvasive method to assess glycogen levels in skeletal muscle and to identify excess glycogen accumulation in patients with glycogen storage disease (GSD). Despite the clinical potential of the method, it is currently not widely used for diagnosis or for follow-up of treatment. While it is possible to perform acceptable 13C MRS at lower fields, the low natural abundance of 13C and the inherently low signal-to-noise ratio of 13C MRS makes it desirable to utilize the advantage of increased signal strength offered by ultra-high fields for more accurate measurements. Concomitant with this advantage, however, ultra-high fields present unique technical challenges that need to be addressed when studying glycogen. In particular, the question of measurement reproducibility needs to be answered so as to give investigators insight into meaningful inter-subject glycogen differences. We measured muscle glycogen levels in vivo in the calf muscle in three patients with McArdle disease (MD), one patient with phosphofructokinase deficiency (PFKD) and four healthy controls by performing 13C MRS at 7T. Absolute quantification of the MRS signal was achieved by using a reference phantom with known concentration of metabolites. Muscle glycogen concentration was increased in GSD patients (31.5±2.9 g/kg w. w.) compared with controls (12.4±2.2 g/kg w. w.). In three GSD patients glycogen was also determined biochemically in muscle homogenates from needle biopsies and showed a similar 2.5-fold increase in muscle glycogen concentration in GSD patients compared with controls. Repeated inter-subject glycogen measurements yield a coefficient of variability of 5.18%, while repeated phantom measurements yield a lower 3.2% system variability. We conclude that noninvasive ultra-high field 13C MRS provides a valuable, highly reproducible tool for quantitative assessment of glycogen levels in health and disease.

  1. A flow-through probe for in Vivo31P NMR spectroscopy of unanesthetized aquatic vertebrates at 9.4 tesla

    NASA Astrophysics Data System (ADS)

    van den Thillart, Guido; Körner, Frans; van Waarde, Aren; Erkelens, Cees; Lugtenburg, Johan

    A flow cell which fits in a modified bioprobe of a Bruker MSL-400 NMR spectrometer and allows the monitoring of the energy metabolism of an enclosed aquatic vertebrate at a selected temperature, water composition, and oxygen level ranging from 0 to 100% air saturation is described. The animal is pressed against the observation window and immobilized by an inflatable plastic bag. No anesthetics are used during the actual experiment. The signal of the tissue of interest is picked up with a surface coil, which is double-tuned to the phosphorus (162 MHz) and proton (400 MHz) frequencies. The flow cell can be moved vertically to the desired position. The usefulness of the fish probe is demonstrated by spectra of excellent resolution and signal-to-noise, obtained from the myotomal muscles of carp, goldfish, rainbow trout, and tilapia, by high phosphocreatine/ inorganic phosphate ratios, indicating a situation of low stress, and by stability of all NMR-observed parameters over periods of at least one working day (8 h).

  2. Multi-channel metabolic imaging, with SENSE reconstruction, of hyperpolarized [1- 13C] pyruvate in a live rat at 3.0 tesla on a clinical MR scanner

    NASA Astrophysics Data System (ADS)

    Tropp, James; Lupo, Janine M.; Chen, Albert; Calderon, Paul; McCune, Don; Grafendorfer, Thomas; Ozturk-Isik, Esin; Larson, Peder E. Z.; Hu, Simon; Yen, Yi-Fen; Robb, Fraser; Bok, Robert; Schulte, Rolf; Xu, Duan; Hurd, Ralph; Vigneron, Daniel; Nelson, Sarah

    2011-01-01

    We report metabolic images of 13C, following injection of a bolus of hyperpolarized [1-13C] pyruvate in a live rat. The data were acquired on a clinical scanner, using custom coils for volume transmission and array reception. Proton blocking of all carbon resonators enabled proton anatomic imaging with the system body coil, to allow for registration of anatomic and metabolic images, for which good correlation was achieved, with some anatomic features (kidney and heart) clearly visible in a carbon image, without reference to the corresponding proton image. Parallel imaging with sensitivity encoding was used to increase the spatial resolution in the SI direction of the rat. The signal to noise ratio in was in some instances unexpectedly high in the parallel images; variability of the polarization among different trials, plus partial volume effects, are noted as a possible cause of this.

  3. Functional MR imaging of visual and motor cortex stimulation at high temporal resolution using a FLASH technique on a standard 1.5 Tesla scanner.

    PubMed

    Wiener, E; Schad, L R; Baudendistel, K T; Essig, M; Müller, E; Lorenz, W J

    1996-01-01

    Functional magnetic resonance imaging (fMRI) was performed on a conventional 1.5 T scanner by means of a modified FLASH-technique at temporal resolutions of 80 and 320 ms. The method's stability was assessed by phantom measurements and by investigation of three volunteers resulting in a low amplitude (3%) periodic (4 s) signal modulation for the in vivo measurements, which was not observable in the phantom experiments. fMRI activation studies of motor and visual cortices of four adjacent slices were carried out on 12 healthy right-handed volunteers. Stimulation was performed by a triggered single white light flash or single finger-to-thumb opposition movement, respectively. Event-related response of visual and motor activation was traced over 10.24 s with a temporal resolution of 320 ms for the four slice measurements. Brain activation maps were calculated by correlation of measured signal time course with a time-shifted boxcar function. Activation was quantified by calculation of percentual signal change in relation to the baseline. Observed signal magnitudes were about 5-7% in visual and about 8-12% in primary motor cortex. While photic response was delayed by about 2 s, motor stimulation showed an instantaneous increase of the MR signal. MR signal responses for both stimuli had decayed completely after about 5 s. Our results show that event-related fMRI enables mapping of brain function at sufficient spatial resolution with a temporal resolution of up to 80 ms on a conventional scanner.

  4. Localization of the cortical motor area by functional magnetic resonance imaging with gradient echo and echo-planar methods, using clinical 1.5 Tesla MR imaging systems.

    PubMed

    Nakayama, K

    1997-06-01

    Functional magnetic resonance imaging (MRI) with gradient echo and echo-planar sequences was applied to healthy volunteers and neurological patients to evaluate the feasibility of detecting and localizing the motor cortex. Time course of the change in signal intensity by an alternate repetition of motor task (squeezing hand) and rest periods was also examined. The motor cortex was localized as the area of signal increase in 88.9% of 45 healthy volunteers by gradient echo method, which mainly reflected the cortical vein, and 83.3% of 30 healthy volunteers by echo-planar method, which mainly reflected the cerebral gyrus. Among 21 volunteers who participated in the both studies, success rate in the localization for the motor cortex was 90.5% (21 volunteers) by gradient echo method and 81% (17 volunteers) by echo-planar method. It was also shown from the time course of the change in signal intensity that signal increase in the most significantly activated area generally corresponded with the periods of the motor task, and the latency between the onset of signal increase and the onset of motor task was usually about 4 seconds. In four of 6 patients with brain tumor, the motor cortex was localized, although activated areas were displaced or distorted. The results indicate that fMRI, either with gradient echo or echo-planar sequence, is a useful method for localizing the primary motor area activated during the motor task and clinically available for noninvasive evaluation of the anatomical relation between brain tumors and the motor area before surgical therapy.

  5. Sodium-23 MRI of whole spine at 3 Tesla using a 5-channel receive-only phased-array and a whole-body transmit resonator.

    PubMed

    Malzacher, Matthias; Kalayciyan, Raffi; Konstandin, Simon; Haneder, Stefan; Schad, Lothar R

    2016-03-01

    Sodium magnetic resonance imaging ((23)Na MRI) is a unique and non-invasive imaging technique which provides important information on cellular level about the tissue of the human body. Several applications for (23)Na MRI were investigated with regard to the examination of the tissue viability and functionality for example in the brain, the heart or the breast. The (23)Na MRI technique can also be integrated as a potential monitoring instrument after radiotherapy or chemotherapy. The main contribution in this work was the adaptation of (23)Na MRI for spine imaging, which can provide essential information on the integrity of the intervertebral disks with respect to the early detection of disk degeneration. In this work, a transmit-only receive-only dual resonator system was designed and developed to cover the whole human spine using (23)Na MRI and increase the receive sensitivity. The resonator system consisted of an already presented (23)Na whole-body resonator and a newly developed 5-channel receive-only phased-array. The resonator system was first validated using bench top and phantom measurements. A threefold SNR improvement at the depth of the spine (∼7cm) over the whole-body resonator was achieved using the spine array. (23)Na MR measurements of the human spine using the transmit-only receive-only resonator system were performed on a healthy volunteer within an acquisition time of 10minutes. A density adapted 3D radial sequence was chosen with 6mm isotropic resolution, 49ms repetition time and a short echo time of 540μs. Furthermore, it was possible to quantify the tissue sodium concentration in the intervertebral discs in the lumbar region (120ms repetition time) using this setup.

  6. Dapsone improves functional deficit and diminishes brain damage evaluated by 3-Tesla magnetic resonance image after transient cerebral ischemia and reperfusion in rats.

    PubMed

    Diaz-Ruiz, Araceli; Roldan-Valadez, Ernesto; Ortiz-Plata, Alma; Mondragón-Lozano, Rodrigo; Heras-Romero, Yessica; Mendez-Armenta, Marisela; Osorio-Rico, Laura; Nava-Ruiz, Concepción; Ríos, Camilo

    2016-09-01

    Stroke is a frequent cause of death and the first of disability in the world population. We have shown that dapsone acts as an antioxidant, antiinflammatory and antiapoptotic agent after brain Ischemia reperfusion (I/R) in rats; however, its therapeutic efficacy, measured by imaging has not been characterized. In this context, the aim of this study was to evaluate the neuroprotective effect of dapsone by magnetic resonance imaging (MRI) and to correlate imaging markers with motor function and oxidative stress after transient cerebral ischemia and reperfusion (I/R). We used male rats throughout the experiment. Functional deficit after I/R was assessed by using Longa scale. The area of brain tissue damage was measured by histology. The nuclear factor erythroid 2-related factor 2 (Nrf-2) and the amount of reactive oxygen species (ROS) were measured as biomarkers of oxidative stress. Finally, difussion tensor MRI was employed to measure the fractional anisotropy (FA), as a MRI marker of the pathophysiologic brain status. Results showed a better functional recovery and less damaged tissue in animals treated with dapsone vs control group. The values of FA were higher in animals receiving treatment, indicating a better preservation of brain structure. At early stages of the damage, dapsone was able to reduce both oxidative markers (Nrf-2 and ROS). Our findings provide new evidence for the efficacy of dapsone when administered during the acute phase after I/R and that quantitative sequences of MRI are useful for characterizing its potential therapeutic benefits after stroke.

  7. Development and Evaluation of an Algorithm for the Computer-Assisted Segmentation of the Human Hypothalamus on 7-Tesla Magnetic Resonance Images

    PubMed Central

    Schmidt, Laura; Anwander, Alfred; Strauß, Maria; Trampel, Robert; Bazin, Pierre-Louis; Möller, Harald E.; Hegerl, Ulrich; Turner, Robert; Geyer, Stefan

    2013-01-01

    Post mortem studies have shown volume changes of the hypothalamus in psychiatric patients. With 7T magnetic resonance imaging this effect can now be investigated in vivo in detail. To benefit from the sub-millimeter resolution requires an improved segmentation procedure. The traditional anatomical landmarks of the hypothalamus were refined using 7T T1-weighted magnetic resonance images. A detailed segmentation algorithm (unilateral hypothalamus) was developed for colour-coded, histogram-matched images, and evaluated in a sample of 10 subjects. Test-retest and inter-rater reliabilities were estimated in terms of intraclass-correlation coefficients (ICC) and Dice's coefficient (DC). The computer-assisted segmentation algorithm ensured test-retest reliabilities of ICC≥.97 (DC≥96.8) and inter-rater reliabilities of ICC≥.94 (DC = 95.2). There were no significant volume differences between the segmentation runs, raters, and hemispheres. The estimated volumes of the hypothalamus lie within the range of previous histological and neuroimaging results. We present a computer-assisted algorithm for the manual segmentation of the human hypothalamus using T1-weighted 7T magnetic resonance imaging. Providing very high test-retest and inter-rater reliabilities, it outperforms former procedures established at 1.5T and 3T magnetic resonance images and thus can serve as a gold standard for future automated procedures. PMID:23935821

  8. Relaxation time measurements of bone marrow protons in the calcaneus using a compact MRI system at 0.2 Tesla field strength.

    PubMed

    Tomiha, Sadanori; Iita, Nachiko; Okada, Fumi; Handa, Shinya; Kose, Katsumi

    2008-08-01

    Relaxation times (T(1) and T(2)) of the bone marrow protons and trabecular bone volume fraction (TBVF) in the calcaneus were measured for 100 female volunteers using a compact MRI system at 0.2 T field strength. The speed of sound (SOS) through the calcaneus was measured also for the same subjects using a quantitative ultrasound system. Both relaxation times were found to have positive correlations with age (R = 0.40; P < 0.0001 and R = 0.31; P < 0.002, respectively) and negative correlations with SOS (R = -0.38; P < 0.0001 and R = -0.38; P < 0.0001, respectively). Although TBVF had a fairly high positive correlation with the SOS (R = 0.67), neither T(1) nor T(2) were correlated with TBVF (R = -0.062 and -0.024, respectively). These results suggest that the age dependence of both T(1) and T(2) is caused by the microdynamic properties of the lipid molecules in bone marrow observed using acoustic or elastic modalities. PMID:18666107

  9. Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla.

    PubMed

    Stier, Andreas V; McCreary, Kathleen M; Jonker, Berend T; Kono, Junichiro; Crooker, Scott A

    2016-02-09

    In bulk and quantum-confined semiconductors, magneto-optical studies have historically played an essential role in determining the fundamental parameters of excitons (size, binding energy, spin, dimensionality and so on). Here we report low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T. Both the A and B excitons exhibit similar Zeeman splittings of approximately -230 μeV T(-1) (g-factor ≃-4), thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides. Crucially, these large fields also allow observation of the small quadratic diamagnetic shifts of both A and B excitons in monolayer WS2, from which radii of ∼1.53 and ∼1.16 nm are calculated. Further, when analysed within a model of non-local dielectric screening, these diamagnetic shifts also constrain estimates of the A and B exciton binding energies (410 and 470 meV, respectively, using a reduced A exciton mass of 0.16 times the free electron mass). These results highlight the utility of high magnetic fields for understanding new two-dimensional materials.

  10. Optimized [1-13C]glucose infusion protocol for 13C magnetic resonance spectroscopy at 3 Tesla of human brain glucose metabolism under euglycemic and hypoglycemic conditions

    PubMed Central

    van de Ven, Kim C.C.; van der Graaf, Marinette; Tack, Cees J.J.; Klomp, Dennis W.J.; Heerschap, Arend; de Galan, Bastiaan E.

    2009-01-01

    The effect of insulin-induced hypoglycemia on cerebral glucose metabolism is largely unknown. 13C MRS is a unique tool to study cerebral glucose metabolism, but the concurrent requirement for [1-13C]glucose administration limits its use under hypoglycemic conditions. To facilitate 13C MRS data analysis we designed separate [1-13C]glucose infusion protocols for hyperinsulinemic euglycemic and hypoglycemic clamps in such a way that plasma isotopic enrichment of glucose was stable and comparable under both glycemic conditions. 13C MR spectra were acquired with optimized 13C MRS measurement techniques to obtain high quality 13C MR spectra with these protocols. PMID:19913052

  11. Overdrainage of cerebrospinal fluid caused by detachment of the pressure control cam in a programmable valve after 3-tesla magnetic resonance imaging.

    PubMed

    Watanabe, Atsushi; Seguchi, Tatsuya; Hongo, Kazuhiro

    2010-02-01

    The authors report a rare case of overdrainage of the CSF caused by the malfunction of a Codman-Hakim programmable valve (CHPV) following a 3-T MR imaging procedure. Nine years ago this 72-year-old woman underwent ventriculoperitoneal shunt placement with a CHPV system for hydrocephalus due to subarachnoid hemorrhage. The postoperative course was uneventful and the system functioned well. A radiograph obtained immediately after 3-T MR imaging revealed that the pressure control cam in the valve system was detached from the base plate. Intracranial hypotension syndrome occurred several hours after the MR imaging study, and a CT scan revealed a decrease in ventricle size. A revision of the system promptly resolved the symptoms, and a postoperative CT scan revealed that the ventricle size was restored to normal. Examination of the extracted valve showed a Y-shaped crack in the plastic housing as well as detachment of the white marker and cam from the base plate. A reduction in the power of the flat spring to press the valve ball led to CSF overdrainage because of a loss of support by the cam. Because the patient had incurred no head injury during the day and radiographic studies of the system 5 years previously had shown detachment of the white marker, damage to the system might have been caused by a past impact. These facts may indicate that the antimagnetic performance of the system could have decreased due to a previous impact and that the strong magnetic force in a 3-T MR imaging environment might have caused detachment of the cam. PMID:19408984

  12. Is the Volume of the Caudate Nuclei Associated With Area of Secondary Hyperalgesia? – Protocol for a 3-Tesla MRI Study of Healthy Volunteers

    PubMed Central

    Asghar, Mohammad Sohail; Wetterslev, Jørn; Pipper, Christian Bressen; Johan Mårtensson, Johan; Becerra, Lino; Christensen, Anders; Nybing, Janus Damm; Havsteen, Inger; Boesen, Mikael; Dahl, Jørgen Berg

    2016-01-01

    Background Experience and development of pain may be influenced by a number of physiological, psychological, and psychosocial factors. In a previous study we found differences in neuronal activation to noxious stimulation, and microstructural neuroanatomical differences, when comparing healthy volunteers with differences in size of the area of secondary hyperalgesia following a standardized burn injury. Objective We aim to investigate the degree of association between the volume of pain-relevant structures in the brain and the size of the area of secondary hyperalgesia following brief thermal sensitization. Methods The study consists of one experimental day, in which whole-brain magnetic resonance imaging (MRI) scans will be conducted including T1-weighed three-dimensional anatomy scan, diffusion tensor imaging, and resting state functional MRI. Before the experimental day, all included participants will undergo experimental pain testing in a parallel study (Clinicaltrials.gov Identifier: NCT02527395). Results from this experimental pain testing, as well as the size of the area of secondary hyperalgesia from the included participants, will be extracted from this parallel study. Results The association between the volume of pain-relevant structures in the brain and the area of secondary hyperalgesia will be investigated by linear regression of the estimated best linear unbiased predictors on the individual volumes of the pain relevant brain structures. Conclusions We plan to investigate the association between experimental pain testing parameters and the volume, connectivity, and resting state activity of pain-relevant structures in the brain. These results may improve our knowledge of the mechanisms responsible for the development of acute and chronic pain. ClinicalTrial Danish Research Ethics Committee (identifier: H-15010473). Danish Data Protection Agency (identifier: RH-2015-149). Clinicaltrials.gov NCT02567318; http://clinicaltrials.gov/ct2/show/NCT02567318 (Archived by WebCite at http://www.webcitation.org/6i4OtP0Oi) PMID:27317630

  13. Highly adaptive RF excitation scheme based on conformal resonant CRLH metamaterial ring antennas for 7-Tesla traveling-wave magnetic resonance imaging.

    PubMed

    Erni, Daniel; Liebig, Thorsten; Rennings, Andreas; Koster, Norbert H L; Fröhlich, Jürg

    2011-01-01

    We propose an adaptive RF antenna system for the excitation (and manipulation) of the fundamental circular waveguide mode (TE(11)) in the context of high-field (7T) traveling-wave magnetic resonance imaging (MRI). The system consists of composite right-/left-handed (CRLH) meta-material ring antennas that fully conforms to the inner surface of the MRI bore. The specific use of CRLH metamaterials is motivated by its inherent dispersion engineering capabilities, which is needed when designing resonant ring structures for virtually any predefined diameter operating at the given Larmor frequency (i.e. 298 MHz). Each functional group of the RF antenna system consists of a pair of subsequently spaced and correspondingly fed CRLH ring antennas, allowing for the unidirectional excitation of propagating, circularly polarized B(1) mode fields. The same functional group is also capable to simultaneously mold an incoming, counter-propagating mode. Given these functionalities we are proposing now a compound scheme (i.e. periodically arranged multiple antenna pairs)--termed as "MetaBore"--that is apt to provide a tailored RF power distribution as well as full wave reflection compensation virtually at any desired location along the bore.

  14. Quantitative comparison of cortical surface reconstructions from MP2RAGE and Multi-Echo MPRAGE data at 3 and 7 Tesla

    PubMed Central

    Fujimoto, Kyoko; Polimeni, Jonathan R.; van der Kouwe, Andre J. W.; Reuter, Martin; Kober, Tobias; Benner, Thomas; Fischl, Bruce; Wald, Lawrence L.

    2014-01-01

    The Magnetization-Prepared 2 Rapid Acquisition Gradient Echo (MP2RAGE) method achieves spatially uniform contrast across the entire brain between gray matter and surrounding white matter tissue and cerebrospinal fluid by rapidly acquiring data at two points during an inversion recovery, and then combining the two volumes so as to cancel out sources of intensity and contrast bias, making it useful for neuroimaging studies at ultrahigh field strengths (≥ 7 T). To quantify the effectiveness of the MP2RAGE method for quantitative morphometric neuroimaging, we performed tissue segmentation and cerebral cortical surface reconstruction of the MP2RAGE data and compared the results with those generated from conventional Multi-Echo MPRAGE (MEMPRAGE) data across a group of healthy subjects. To do so, we developed a preprocessing scheme for the MP2RAGE image data to allow for automatic cortical segmentation and surface reconstruction using FreeSurfer and analysis methods to compare positioning of the surface meshes. Using image volumes with 1 mm isotropic voxels we found a scan-rescan reproducibility of cortical thickness estimates to be 0.15 mm (or 6%) for the MEMPRAGE data and a slightly lower reproducibility of 0.19 mm (or 8%) for the MP2RAGE data. We also found that the thickness estimates were systematically smaller in the MP2RAGE data, and that both the interior and exterior cortical boundaries estimated from the MP2RAGE data were consistently positioned within the corresponding boundaries estimated from the MEMPRAGE data. Therefore several measureable differences exist in the appearance of cortical gray matter and its effect on automatic segmentation methods that must be considered when choosing an acquisition or segmentation method for studies requiring cortical surface reconstructions. We propose potential extensions to the MP2RAGE method that may help to reduce or eliminate these discrepancies. PMID:24345388

  15. A Nondestructive Method to Distinguish the Internal Constituent Architecture of the Intervertebral Discs Using 9.4 Tesla Magnetic Resonance Imaging

    PubMed Central

    Wijayathunga, Vithanage N.; Ridgway, John P.; Ingham, Eileen; Treanor, Darren; Carey, Duane; Bulpitt, Andy; Magee, Derek; Damion, Robin; Wilcox, Ruth K.

    2015-01-01

    Study Design. An in vitro study of the intervertebral disc (IVD) structure using 9.4T magnetic resonance imaging (MRI). Objective. Investigate the potential of ultrahigh-field strength MRI for higher quality 3-dimensional (3D) volumetric MRI datasets of the IVD to better distinguish structural details. Summary of Background Data. MRI has the advantages of being nondestructive and 3D in comparison to most techniques used to obtain the structural details of biological tissues, however, its poor image quality at higher resolution is a limiting factor. Ultrahigh-field MRI could improve the imaging of biological tissues but the current understanding of its application for spinal tissue is limited. Methods. 2 ovine spinal segments (C7–T1, T2–T3) containing the IVD were separately imaged using 2 sequences; 3D spin echo (multislice-multiecho) pulse sequence for the C7–T1 sample and 3D gradient echo (fast-low-angle-shot) pulse sequence for the T2–T3 sample. The C7–T1 sample was subsequently decalcified and imaged again using the same scanning parameters. Histological sections obtained from the decalcified sample were stained followed by digital scanning. Observations from corresponding MRI slices and histological sections were compared as a method of confirmation of morphology captured under MRI. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and relative-contrast values were calculated for quantitative evaluation of image quality. Results. Measurements from histology sections and corresponding MRI slices matched well. Both sequences revealed finer details of the IVD structure. Under the spin echo sequence, the annulus lamellae architecture was distinguishable and the SNR and CNR values were higher. The relative contrast was considerably higher between high (nucleus) and low (bone) signal constituents, but between the nucleus and the annulus the relative contrast was low. Under the gradient echo sequence, although the relative contrasts between constituents were poor, the fiber orientation was clearly manifested. Conclusion. The obtained positive results demonstrate the potential of ultrahigh-field strength MRI to nondestructively capture the IVD structure. Level of Evidence: N/A PMID:26244404

  16. 1H NMR spectroscopy of rat brain in vivo at 14.1 Tesla: Improvements in quantification of the neurochemical profile

    NASA Astrophysics Data System (ADS)

    Mlynárik, Vladimír; Cudalbu, Cristina; Xin, Lijing; Gruetter, Rolf

    2008-10-01

    Ultra-short echo-time proton single voxel spectra of rat brain were obtained on a 14.1 T 26 cm horizontal bore system. At this field, the fitted linewidth in the brain tissue of adult rats was about 11 Hz. New, separated resonances ascribed to phosphocholine, glycerophosphocholine and N-acetylaspartate were detected for the first time in vivo in the spectral range of 4.2-4.4 ppm. Moreover, improved separation of the resonances of lactate, alanine, γ-aminobutyrate, glutamate and glutathione was observed. Metabolite concentrations were estimated by fitting in vivo spectra to a linear combination of simulated spectra of individual metabolites and a measured spectrum of macromolecules (LCModel). The calculated concentrations of metabolites were generally in excellent agreement with those obtained at 9.4 T. These initial results further indicated that increasing magnetic field strength to 14.1 T enhanced spectral resolution in 1H NMR spectroscopy. This implies that the quantification of the neurochemical profile in rodent brain can be achieved with improved accuracy and precision.

  17. Using Nikola Tesla's Story and His Experiments as Presented in the Film "The Prestige" to Promote Scientific Inquiry: A Report of an Action Research Project

    ERIC Educational Resources Information Center

    Hadzigeorgiou, Yannis; Garganourakis, Vassilios

    2010-01-01

    This paper reports on an action research project undertaken with the primary aim of investigating the extent to which situations that evoke a sense of wonder can promote scientific inquiry. Given the intense interest, curiosity, and wonder that some students had begun to develop after seeing the film "The Prestige", a science teacher used this…

  18. Non-Invasive Evaluation of the GABAergic/Glutamatergic System in Autistic Patients Observed by MEGA-Editing Proton MR Spectroscopy Using a Clinical 3 Tesla Instrument

    ERIC Educational Resources Information Center

    Harada, Masafumi; Taki, Masako M.; Nose, Ayumi; Kubo, Hitoshi; Mori, Kenji; Nishitani, Hiromu; Matsuda, Tsuyoshi

    2011-01-01

    Amino acids related to neurotransmitters and the GABAergic/glutamatergic system were measured using a 3 T-MRI instrument in 12 patients with autism and 10 normal controls. All measurements were performed in the frontal lobe (FL) and lenticular nuclei (LN) using a conventional sequence for n-acetyl aspartate (NAA) and glutamate (Glu), and the…

  19. The Travelling-Wave Primate System: A New Solution for Magnetic Resonance Imaging of Macaque Monkeys at 7 Tesla Ultra-High Field

    PubMed Central

    Herrmann, Tim; Mallow, Johannes; Plaumann, Markus; Luchtmann, Michael; Stadler, Jörg; Mylius, Judith; Brosch, Michael; Bernarding, Johannes

    2015-01-01

    Introduction Neuroimaging of macaques at ultra-high field (UHF) is usually conducted by combining a volume coil for transmit (Tx) and a phased array coil for receive (Rx) tightly enclosing the monkey’s head. Good results have been achieved using vertical or horizontal magnets with implanted or near-surface coils. An alternative and less costly approach, the travelling-wave (TW) excitation concept, may offer more flexible experimental setups on human whole-body UHF magnetic resonance imaging (MRI) systems, which are now more widely available. Goal of the study was developing and validating the TW concept for in vivo primate MRI. Methods The TW Primate System (TWPS) uses the radio frequency shield of the gradient system of a human whole-body 7 T MRI system as a waveguide to propagate a circularly polarized B1 field represented by the TE11 mode. This mode is excited by a specifically designed 2-port patch antenna. For receive, a customized neuroimaging monkey head receive-only coil was designed. Field simulation was used for development and evaluation. Signal-to-noise ratio (SNR) was compared with data acquired with a conventional monkey volume head coil consisting of a homogeneous transmit coil and a 12-element receive coil. Results The TWPS offered good image homogeneity in the volume-of-interest Turbo spin echo images exhibited a high contrast, allowing a clear depiction of the cerebral anatomy. As a prerequisite for functional MRI, whole brain ultrafast echo planar images were successfully acquired. Conclusion The TWPS presents a promising new approach to fMRI of macaques for research groups with access to a horizontal UHF MRI system. PMID:26066653

  20. Biological responses of human solid tumor cells to X-ray irradiation within a 1.5-Tesla magnetic field generated by a magnetic resonance imaging-linear accelerator.

    PubMed

    Wang, Li; Hoogcarspel, Stan Jelle; Wen, Zhifei; van Vulpen, Marco; Molkentine, David P; Kok, Jan; Lin, Steven H; Broekhuizen, Roel; Ang, Kie-Kian; Bovenschen, Niels; Raaymakers, Bas W; Frank, Steven J

    2016-10-01

    Devices that combine magnetic resonance imaging with linear accelerators (MRL) represent a novel tool for MR-guided radiotherapy. However, whether magnetic fields (MFs) generated by these devices affect the radiosensitivity of tumors is unknown. We investigated the influence of a 1.5-T MF on cell viability and radioresponse of human solid tumors. Human head/neck cancer and lung cancer cells were exposed to single or fractionated 6-MV X-ray radiation; effects of the MF on cell viability were determined by cell plating efficiency and on radioresponsiveness by clonogenic cell survival. Doses needed to reduce the fraction of surviving cells to 37% of the initial value (D0s) were calculated for multiple exposures to MF and radiation. Results were analyzed using Student's t-tests. Cell viability was no different after single or multiple exposures to MRL than after exposure to a conventional linear accelerator (Linac, without MR-generated MF) in 12 of 15 experiments (all P > 0.05). Single or multiple exposures to MF had no influence on cell radioresponse (all P > 0.05). Cells treated up to four times with an MRL or a Linac further showed no changes in D0s with MF versus without MF (all P > 0.05). In conclusion, MF within the MRL does not seem to affect in vitro tumor radioresponsiveness as compared with a conventional Linac. Bioelectromagnetics. 37:471-480, 2016. © 2016 Wiley Periodicals, Inc. PMID:27434783

  1. Design considerations of a power supply system for fast cycling superconducting accelerator magnets of 2 Tesla b-field generated by a conductor of 100 kA current

    SciTech Connect

    Hays, Steve; Piekarz, Henryk; Pfeffer, Howie; Claypool, Brad; /Fermilab

    2007-06-01

    Recently proposed fast cycling accelerators for proton drivers (SF-SPS, CERN and SF-MR, SF-BOOSTER, FNAL) neutrino sources require development of new magnet technology. In support of this magnet development a power supply system will need to be developed that can support the high current and high rate of power swing required by the fast cycling (1 sec rise and fall in the SF-MR, 5Hz in Booster). This paper will outline a design concept for a +/- 2000 V and 100,000 A fast ramping power supply system. This power supply design is in support of a 6.44 km magnet system at 0.020 H and 330 m 5 Hz, 0.00534 H superconducting loads. The design description will include the layout and plan for extending the present FNAL Main Injector style ramping power supply to the higher currents needed for this operation. This will also include the design for a harmonic filter and power factor corrector that will be needed to control the large power swings caused by the fast cycle time. A conceptual design for the current regulation system and control will also be outlined. The power circuit design will include the bridge, filter and transformer plan based on existing designs.

  2. Potential heating caused by intraparenchymal intracranial pressure transducers in a 3-tesla magnetic resonance imaging system using a body radiofrequency resonator: assessment of the Codman MicroSensor Transducer.

    PubMed

    Newcombe, Virginia F J; Hawkes, Robert C; Harding, Sally G; Willcox, Roslyn; Brock, Sarah; Hutchinson, Peter J; Menon, David K; Carpenter, T Adrian; Coles, Jonathan P

    2008-07-01

    Magnetic resonance imaging and spectroscopy may provide important clinical information in the acute stages of brain injury. For this to occur it must be ensured that intracranial pressure (ICP) monitoring devices are safe to bring into the MR imaging suite. The authors tested a Codman MicroSensor ICP Transducer (Codman & Shurtleff, Inc.) within a 3-T MR imaging system using the transmit body coil and receive-only coils and the transmit-and-receive head coil. Extreme and rapid heating of 64 degrees C was noted with the transducer wire in certain positions when using the transmit body coil and receive-only head coil. This is consistent with the phenomenon of resonance, and the probe was shown to have a distinct resonant response when coupled to HP 4195A Network Analyzer (Hewlett Packard). Coiling some of the transducer wire outside of the receive-only head coil reduced the generated current and so stopped the thermogenesis. This may be due to the introduction of a radiofrequency choke. The ICP transducer performed within clinically acceptable limits in both the static magnetic field and during imaging with high radiofrequency power when the excess wire was in this configuration. No heating was observed when a transmit-and-receive head coil was used. This study has shown when using a high-field magnet, the Codman ICP probe is MR conditional. That is, in the authors' system, it can be safely used with the transmit-and-receive head coil, but when using the transmit body coil the transducer wire must be coiled into concentric loops outside of the receive-only head coil.

  3. Superconductivity in Strong Magnetic Field (Greater Than Upper Critical Field)

    SciTech Connect

    Tessema, G.X.; Gamble, B.K.; Skove, M.J.; Lacerda, A.H.; Mielke, C.H.

    1998-08-22

    The National High Magnetic Field Laboratory, funded by the National Science Foundation and other US federal Agencies, has in recent years built a wide range of magnetic fields, DC 25 to 35 Tesla, short pulse 50 - 60 Tesla, and quasi-continuous 60 Tesla. Future plans are to push the frontiers to 45 Tesla DC and 70 to 100 Tesla pulse. This user facility, is open for national and international users, and creates an excellent tool for materials research (metals, semiconductors, superconductors, biological systems ..., etc). Here we present results of a systematic study of the upper critical field of a novel superconducting material which is considered a promising candidate for the search for superconductivity beyond H{sub c2} as proposed by several new theories. These theories predict that superconductors with low carrier density can reenter the superconducting phase beyond the conventional upper critical field H{sub c2}. This negates the conventional thinking that superconductivity and magnetic fields are antagonistic.

  4. Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER) supplement. Magnet system special investigations

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The results of magnet system special investigations listed below are summarized: 4 Tesla Magnet Alternate Design Study; 6 Tesla Magnet Manufacturability Study. The conceptual design for a 4 Tesla superconducting magnet system for use with an alternate (supersonic) ETF power train is described, and estimated schedule and cost are identified. The magnet design is scaled from the ETF 6 T Tesla design. Results of a manufacturability study and a revised schedule and cost estimate for the ETF 6 T magnet are reported. Both investigations are extensions of the conceptual design of a 6 T magnet system performed earlier as a part of the overall MED-ETF conceptual design described in Conceptual Design Engineering Report (CDER) Vol. V, System Design Description (SDD) 503 dated September, 1981, DOE/NASA/0224-1; NASA CR-165/52.

  5. Performance predictions for a room temperature, Ericsson cycle, magnetic heat pump

    NASA Astrophysics Data System (ADS)

    Purnell, J. G.

    1982-05-01

    The performance potential of a room temperature magnetic heat pump utilizing Gadolinium and operating on an Ericsson Cycle was investigated at magnetic flux densities of 2 and 7-Tesla which represent the upper limits of conventional and superconducting electromagnetics, respectively. At a coefficient of performance of 5, a 7-Tesla system would provide a cooling capacity of at best 1200 BTU per hour per pound of Gadolinium while a 2-Tesla system would operate at approximately 130 BTU per hour per pound of Gadolinium. Magnetic circuit efficiency was not determined but must be high (95-percent or better) in order for the magnetic heat pump performance to compete with conventional cooling systems. It is unlikely the magnetic heat pump investigated could approach the performance and compactness of the conventional cooling systems unless field strengths much greater than 7-Tesla are possible.

  6. Three Inexpensive Static-Electricity Demonstrations.

    ERIC Educational Resources Information Center

    Gore, Gordon R.; Gregg, William R.

    1992-01-01

    Describes demonstrations to (1) construct an inexpensive static electricity detector; (2) obtain an abundant supply of either negative or positive charge using household items; and (3) create static electricity using a Tesla coil or Van de Graaff generator. (MDH)

  7. Fabrication and applications of electrets

    NASA Technical Reports Server (NTRS)

    Pillai, P. K. C.; Shriver, E. L.

    1977-01-01

    Permanently charged dielectrics can be made less expensively, faster, and more effectively using improved techniques and materials. Methods include charge injection, Tesla-coil charging, and molten spray. Possible uses include pollution control, low-power sensors, and illumination control.

  8. Superconducting Nb3Ge for high-field magnets

    NASA Technical Reports Server (NTRS)

    Braginski, A. I.; Daniel, M. R.; Roland, C. W.; Woollam, J. A.

    1978-01-01

    Superconducting Nb3Ge tape conductors 5 to 10 m long were fabricated by chemical vapor deposition. Such tapes could be used in high-field magnet applications. Average tape properties set the upper performance limit of a magnet at 17 teslas (4.2 K). Highest critical-current densities obtained in thin and layered films set the upper performance limit at 20 teslas (4.2 K).

  9. Scaling Rules for Pre-Injector Design

    SciTech Connect

    Tom Schwarz; Dan Amidei

    2003-07-13

    Proposed designs of the prebunching system of the NLC and TESLA are based on the assumption that scaling the SLC design to NLC/TESLA requirements should provide the desired performance. A simple equation is developed to suggest a scaling rule in terms of bunch charge and duration. Detailed simulations of prebunching systems scaled from a single design have been run to investigate these issues.

  10. Chondrule magnetic properties

    NASA Technical Reports Server (NTRS)

    Wasilewski, P. J.; Obryan, M. V.

    1994-01-01

    The topics discussed include the following: chondrule magnetic properties; chondrules from the same meteorite; and REM values (the ratio for remanence initially measured to saturation remanence in 1 Tesla field). The preliminary field estimates for chondrules magnetizing environments range from minimal to a least several mT. These estimates are based on REM values and the characteristics of the remanence initially measured (natural remanence) thermal demagnetization compared to the saturation remanence in 1 Tesla field demagnetization.

  11. [In Process Citation].

    PubMed

    Južnič, Stanislav

    2015-01-01

    Tesla's academic genealogy is provided and focused on chemical sciences. His teachers of chemical and related fields from all schools he attended in Rakovac, Graz, and Prague were taken into consideration. The research provides the hints into the development of Tesla's idea of chemical nature of matter related to his academic predecessors Bošković, Boerhaave, Stahl, Volta, and several researchers connected with Slovenian lands. PMID:26085434

  12. Alterations in the rat electrocardiogram induced by stationary magnetic fields

    SciTech Connect

    Gaffey, C.T.; Tenforde, T.S.

    1981-01-01

    A field strength dependent increase in the amplitude of the T-wave signal in the rat electrocardiogram (ECG) was observed during exposure to homogeneous, stationary magnetic fields. For 24 adult Sprague-Dswley and Buffalo rats of both sexes, the T-wave amplitude was found to increase by an average of 408% in a 2.0 Tesla (1 Tesla = 10/sup 4/ Gauss) field. No significant magnetically induced changes were observed in other components of the ECG record, including the P wave and the QRS complex. The minimum field level at which augmentation of the T wave could be detected was 0.3 Tesla. The magnetically induced increase in T-wave amplitude occurred instantaneously, and was immediately reversible after exposure to fields as high as 2.0 Tesla. No abnormalities in any component of the ECG record, including the T wave, were noted during a period of 3 weeks following cessation of a continuous 5-h exposure of rats to a 1.5-Tesla field. The heart rate and breathing rate of adult rats were not altered during, or subsequent to, application of fields up to 2.0 Tesla. The effect of animal orientation within the field was tested using juvenile rats 3-14 days old. The maximum increase in T-wave amplitude was observed when subjects were placed with the long axis of the body perpendicular to the lines of magnetic induction. (JMT)

  13. The Road to FUNCTIONAL IMAGING and ULTRAHIGH FIELDS

    PubMed Central

    Uğurbil, Kâmil

    2012-01-01

    The Center for Magnetic Resonance (CMRR) at the University of Minnesota was one of laboratories where the work that simultaneously and independently introduced functional magnetic resonance imaging (fMRI) of human brain activity was carried out. However, unlike other laboratories pursuing fMRI at the time, our work was performed at 4 Tesla magnetic field and coincided with the effort to push human magnetic resonance imaging to field strength significantly beyond 1.5 Tesla which was the high-end standard of the time. The human fMRI experiments performed in CMRR were planned between two colleagues who had known each other and had worked together previously in Bell Laboratories, namely Seiji Ogawa and myself, immediately after the Blood Oxygenation Level Dependent (BOLD) contrast was developed by Seiji. We were waiting for our first human system, a 4 Tesla system, to arrive in order to attempt at imaging brain activity in the human brain and these were the first experiments we performed on the 4 Tesla instrument in CMRR when it became marginally operational. This was a prelude to a subsequent systematic push we initiated for exploiting higher magnetic fields to improve the accuracy and sensitivity of fMRI maps, first going to 9.4 Tesla for animal model studies and subsequently developing a 7 Tesla human system for the first time. Steady improvements in high field instrumentation and ever expanding armamentarium of image acquisition and engineering solutions to challenges posed by ultrahigh fields has brought fMRI to submillimeter resolution in the whole brain at 7 Tesla, the scale necessary to reach cortical columns and laminar differentiation in the whole brain. The solutions that emerged in response to technological challenges posed by 7 Tesla also propagated and continues to propagate to lower field clinical systems, a major advantage of the ultrahigh fields effort that is underappreciated. Further improvements at 7T are inevitable. Further translation of these

  14. Genotoxic Effects of Superconducting Static Magnetic Fields (SMFs) on Wheat (Triticum aestivum) Pollen Mother Cells (PMCs)

    NASA Astrophysics Data System (ADS)

    Zhang, Pingping; Yin, Ruochun; Chen, Zhiyou; Wu, Lifang; Yu, Zengliang

    2007-04-01

    The effects of superconducting static magnetic fields (SMFs) on the pollen mother cells (PMCs) of wheat were investigated in order to evaluate the possible genotoxic effect of such non-ionizing radiation. The seeds of wheat were exposed to static magnetic fields with either different magnetic flux densities (0, 1, 3, 5 and 7 Tesla) for 5 h or different durations (1, 3 and 5 h) at a magnetic flux density of 7 Tesla. The seeds were germinated at 23oC after exposure and the seedlings were transplanted into the field. The PMCs from young wheat ears were taken and slides were made following the conventional method. The genotoxic effect was evaluated in terms of micronucleus (MN), chromosomal bridge, lagging chromosome and fragments in PMCs. Although the exposed groups of a low field intensity (below 5 Tesla) showed no statistically significant difference in the aberration frequency compared with the unexposed control groups and sham exposed groups, a significant increase in the chromosomal bridge, lagging chromosome, triple-polar segregation or micronucleus was observed at a field strength of 5 Tesla or 7 Tesla, respectively. The analysis of dose-effect relationships indicated that the increased frequency of meiotic abnormal cells correlated with the flux density of the magnetic field and duration, but no linear relationship was observed. Such statistically significant differences indicated a potential genotoxic effect of high static magnetic fields above 5 T.

  15. Cognitive, cardiac, and physiological safety studies in ultra high field magnetic resonance imaging.

    PubMed

    Kangarlu, A; Burgess, R E; Zhu, H; Nakayama, T; Hamlin, R L; Abduljalil, A M; Robitaille, P M

    1999-12-01

    A systematic analysis of the effect of an 8.0 tesla static magnetic field on physiological and/or cognitive function is presented in the normal volunteer and in the swine. A study of ten human subjects revealed no evidence of detectable changes in body temperature, heart rate, respiratory rate, systolic pressure, and diastolic blood pressure after 1 hour of exposure. In addition, no cognitive changes were detected. Important ECG changes were noted which were related both to the position of the subject in the magnet and to the absolute strength of the magnetic field. As such, the ECG tracing at 8 tesla was not diagnostically useful. Nonetheless, all subjects exhibited normal ECG readings both before and following exposure to the 8 tesla field. Cardiac function was also examined in detail in the swine. No significant changes in body temperature, heart rate, left ventricular pressure, left ventricular end diastollic pressure, time rate of change of left ventricular pressure, myocardial stiffness index, cardiac output, systolic volume, troponin, and potassium levels could be detected following 3 h of exposure to a field strength of 8.0 tesla. It is concluded that no short term cardiac or cognitive effects are observed following significant exposure to a magnetic field of up to 8.0 tesla.

  16. Superposed epoch analysis and storm statistics from 25 years of the global geomagnetic disturbance index, USGS-Dst

    USGS Publications Warehouse

    Gannon, J.L.

    2012-01-01

    Statistics on geomagnetic storms with minima below -50 nanoTesla are compiled using a 25-year span of the 1-minute resolution disturbance index, U.S. Geological Survey Dst. A sudden commencement, main phase minimum, and time between the two has a magnitude of 35 nanoTesla, -100 nanoTesla, and 12 hours, respectively, at the 50th percentile level. The cumulative distribution functions for each of these features are presented. Correlation between sudden commencement magnitude and main phase magnitude is shown to be low. Small, medium, and large storm templates at the 33rd, 50th, and 90th percentile are presented and compared to real examples. In addition, the relative occurrence of rates of change in Dst are presented.

  17. Investigation of Mechanical Activation on Li-N-H Systems Using 6Li Magic Angle Spinning Nuclear Magnetic Resonance at Ultra-High Field

    SciTech Connect

    Hu, Jian Zhi; Kwak, Ja Hun; Yang, Zhenguo; Osborn, William; Markmaitree, Tippawan; Shaw, Leonard D.

    2008-07-15

    Abstract The significantly enhanced spectral resolution in the 6Li MAS NMR spectra of Li-N-H systems at ultra-high field of 21.1 tesla is exploited, for the first time, to study the detailed electronic and chemical environmental changes associated with mechanical activation of Li-N-H system using high energy balling milling. Complementary to ultra-high field studies, the hydrogen discharge dynamics are investigated using variable temperature in situ 1H MAS NMR at 7.05 tesla field. The significantly enhanced spectral resolution using ultra-high filed of 21.1 tesla was demonstrated along with several major findings related to mechanical activation, including the upfield shift of the resonances in 6Li MAS spectra induced by ball milling, more efficient mechanical activation with ball milling at liquid nitrogen temperature than with ball milling at room temperature, and greatly enhanced hydrogen discharge exhibited by the liquid nitrogen ball milled samples.

  18. Test of Two NB Superstructure Prototypes

    SciTech Connect

    Sekutowicz, J.

    2004-04-16

    An alternative layout of the TESLA linear collider [1], based on weakly coupled multi-cell superconducting structures (superstructures), significantly reduces investment cost due to a simplification in the RF system of the main accelerator. In January 1999, preparation of the beam test of the superstructure began in order to prove the feasibility of this layout. Progress in the preparation was reported frequently in Proceedings of TESLA Collaboration Meetings. Last year, two superstructures were installed in the TESLA Test Facility (TTF) linac at DESY to experimentally verify: methods to balance the accelerating gradient in a weakly coupled system, the stability of the energy gain for the entire train of bunches in macro-pulses and the damping of Higher Order Modes (HOMs). We present results of the first cold and beam test of these two Nb prototypes.

  19. Organic Superconductors

    SciTech Connect

    Charles Mielke

    2009-02-27

    Intense magnetic fields are an essential tool for understanding layered superconductors. Fundamental electronic properties of organic superconductors are revealed in intense (60 tesla) magnetic fields. Properties such as the topology of the Fermi surface and the nature of the superconducting order parameter are revealed. With modest maximum critical temperatures~13K the charge transfer salt organic superconductors prove to be incredibly valuable materials as their electronically clean nature and layered (highly anisotropic) structures yield insights to the high temperature superconductors. Observation of de Haas-van Alphen and Shubnikov-de Haas quantum oscillatory phenomena, magnetic field induced superconductivity and re-entrant superconductivity are some of the physical phenomena observed in the charge transfer organic superconductors. In this talk, I will discuss the nature of organic superconductors and give an overview of the generation of intense magnetic fields; from the 60 tesla millisecond duration to the extreme 1000 tesla microsecond pulsed magnetic fields.

  20. Planar Undulator Considerations(LCC-0085)

    SciTech Connect

    Sheppard, J

    2003-10-07

    This note consists of informal working notes that document an effort to understand the TESLA baseline, unpolarized, undulator based positron source. This is the first step in the design process of an undulator based positron system for the NLC. The expressions and methodologies developed herein are used in subsequent memos that reference this note. In regards to the TESLA design, it is found that a 135 m long (versus 100 m length) undulator is consistent with the performance descriptions in the TDR text. And while operation of the TESLA system with a 250 GeV drive beam energy provides a safety margin of a factor of {approx}2 in e{sup +} yield, operation of the same system at 160 GeV results in a yield of about 0.6.

  1. Cardiovascular alterations in Macaca monkeys exposed to stationary magnetic fields: experimental observations and theoretical analysis

    SciTech Connect

    Tenforde, T.S.; Gaffey, C.T.; Moyer, B.R.; Budinger, T.F.

    1983-01-01

    Simultaneous measurements were made of the electrocardiogram (ECG) and the intraarterial blood pressure of adult male Macaca monkeys during acute exposure to homogeneous stationary magnetic fields ranging in strength up to 1.5 tesla. An instantaneous, field strength-dependent increase in the ECG signal amplitude at the locus of the T wave was observed in fields greater than 0.1 tesla. The temporal sequence of this signal in the ECG record and its reversibility following termination of the magnetic field exposure are consistent with an earlier suggestion that it arises from a magnetically induced aortic blood flow potential superimposed on the native T-wave signal. No measurable alterations in blood pressure resulted from exposure to fields up to 1.5 tesla. This experimental finding is in agreement with theoretical calculations of the magnetohydrodynamic effect on blood flow in the major arteries of the cardiovascular system. 27 references, 1 figure, 1 table.

  2. Analysis of coupled electromagnetic-thermal effects in superconducting accelerator magnets

    NASA Astrophysics Data System (ADS)

    Fischer, E.; Kurnyshov, R.; Shcherbakov, P.

    2008-02-01

    FAIR will built 5 magnet rings including two superconducting synchotrons. The SIS100 is the core component of the facility and will be equipped with 2 Tesla dipole magnets pulsed with 4 Tesla/s. The cable of the magnet coils is made of a hollow NbTi composite cable of about 7 mm outer diameter, cooled with two phase helium flow at 4.5 K. We calculate the heat load, the eddy and the hysteresis losses, investigate the impact of the ramping on the magnetic field, on the safety margin of the conductor and the required cooling for all different elements of the magnet including: the coil, the yoke, the bus bars and the beam pipe. This analysis is based on properties measured at cryogenic temperatures and fine detailed FEM models.

  3. Alterations in the rat electrocardiogram induced by stationary magnetic fields

    SciTech Connect

    Gaffey, C.T.; Tenforde, T.S.

    1981-01-01

    A field strength dependent increase in the amplitude of the T-wave signal in the rat electrocardiogram (ECG) was observed during exposure to homogeneous, stationary magnetic fields. For 24 adult Sprague-Dawley and Buffalo rats of both sexes, the T-wave amplitude was found to increase by an average of 408% in a 2.0 Tesla (1 Tesla - 10(4) Gauss) field. No significant magnetically induced changes were observed in other components of the ECG record, including the P wave and the QRS complex. The minimum field level at which augmentation of the T wave could be detected was 0.3 Tesla. The magnetically induced increase in T-wave amplitude occurred instantaneously, and was immediately reversible after exposure to fields as high as 2.0 Tesla. No abnormalities in any component of the ECG record, including the T wave, were noted during a period of 3 weeks following cessation of a continuous 5-h exposure of rats to a 1.5-Tesla field. The heart rate and breathing rate of adult rats were not altered during, or subsequent to, application of fields up to 2.0 Tesla. The effect of animal orientation within the field was tested using juvenile rats 3-14 days old. The maximum increase in T-wave amplitude was observed when subjects were placed with the long axis of the body perpendicular to the lines of magnetic induction. These experimental observations, as well as theoretical considerations, suggest that augmentation of the signal amplitude in the T-wave segment of the ECG may result from a superimposed electrical potential generated by aortic blood flow in the presence of a stationary magnetic field.

  4. Fabrication and Test Results of a Nb3Sn Superconducting Racetrack Dipole Magnet

    SciTech Connect

    Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A. F.; McInturff, A.D.; Millos, G.A.; Morrison, L.; Morrison, M.; Scanlan, R.M.

    2000-02-06

    A 'proof-of-principle' Nb{sub 3}Sn superconducting dual-bore dipole magnet was built from racetrack coils, as a first step in a program to develop an economical, 15 Tesla, accelerator-quality magnet. The mechanical design and magnet fabrication procedures are discussed. No training was required to achieve temperature-dependent plateau currents, despite several thermal cycles that involved partial magnet disassembly and substantial pre-load variations. Subsequent magnets are expected to approach 15 Tesla with substantially improved conductor.

  5. 18T resistive magnet development. Conceptual design second annual report

    SciTech Connect

    Agarwal, K.L.; Burgeson, J.E.; Gurol, H.; Mancuso, A.; Michels, P.H.

    1985-10-01

    This report documents the work performed on a normal conducting magnet during fiscal year 1985. Emphasis, during the study, was on refinement of the structural design and optimization of the coil current density distribution for either maximum field generation or minimum power consumption. The results have shown that one can generate a 4.4 tesla field using 6.14 megawatts or 3.1 tesla at 1.43 megawatts. The structural design has been modified to stiffen the outer turn of the conductor. The modification was confirmed to be structurally adequate by both analysis and test. 37 figs., 21 tabs.

  6. Structure of products of the condensation of. cap alpha. ,. beta. -unsaturated aldehydes with dimedone

    SciTech Connect

    Yurchenko, O.I.; Pushkareva, K.S.; Zheldubovskaya, G.A.; Komarov, N.V. Berkova, G.A.

    1987-10-10

    ..cap alpha..,..beta..-Acetylenic aldehydes and cinnamaldehyde in reaction with dimedone give the corresponding unsaturated bis(dimedonyl)methanes. In the case of acrolein and crotonaldehyde intramolecular cyclization occurs with the participation of hydroxyl of the dimedone fragment and the double bond with the formation of pyran systems. The PMR spectra were determined on Tesla BS-487C (80 MHz) and Tesla BS-467C (60 MHz) spectrometers in chloroform-d, pyridine-d/sub 5/, and trifluoroacetic acid solutions. Internal standards HMDS and methylene chloride.

  7. The preliminary study of the quench protection of an MgB2

    NASA Astrophysics Data System (ADS)

    Juster, F. P.; Berriaud, C.; Bonelli, A.; Pasquet, R.; Przybilski, H.; Schild, T.; Scola, L.

    2014-01-01

    In the framework of general studies currently carried out at CEA/Saclay in collaboration with Sigmaphi Company on dry MgB2 magnet operating at 10 K and medium range field, 1 T up to 4 T., we plan to build a prototype-coil with a commercial MgB2 wire. This coil, the nominal axial magnetic field of which is 1 tesla, will be placed in a 3 teslas background field generated by a classical NbTi coil. This paper deals with the preliminary quench protection studies including stability and quench propagation modeling.

  8. Apparatus and method for magnetically processing a specimen

    SciTech Connect

    Ludtka, Gerard M; Ludtka, Gail M; Wilgen, John B; Kisner, Roger A; Jaramillo, Roger A

    2013-09-03

    An apparatus for magnetically processing a specimen that couples high field strength magnetic fields with the magnetocaloric effect includes a high field strength magnet capable of generating a magnetic field of at least 1 Tesla and a magnetocaloric insert disposed within a bore of the high field strength magnet. A method for magnetically processing a specimen includes positioning a specimen adjacent to a magnetocaloric insert within a bore of a magnet and applying a high field strength magnetic field of at least 1 Tesla to the specimen and to the magnetocaloric insert. The temperature of the specimen changes during the application of the high field strength magnetic field due to the magnetocaloric effect.

  9. The partial Siberian snake experiment at the Brookhaven AGS

    SciTech Connect

    Huang, H.; Caussyn, D.D.; Ellison, T.; Jones, B.; Lee, S.Y.; Schwandt, P.; Ahren, L.; Alessi, J.; Bleser, E.J.; Bunce, G.; Cameron, P.; Courant, E.D.; Foelsche, H.W.; Gardner, C.J.; Geller, J.; Lee, Y.Y.; Makdisi, Y.I.; Mane, S.R.; Ratner, L.; Reece, K.; Roser, T.; Skelly, J.F.; Soukas, A.; Tepikian, S.; Thern, R.E.; van Asselt, W.; Spinka, H.; Teng, L.; Underwood, D.G.; Yokosawa, A.; Wienands, U.; Bharadwaj, V.; Hsueh, S.; Hiramatsu, S.; Mori, Y.; Sato, H.; Yokoya, K.

    1992-12-31

    We are building a 4.7 Tesla-meter room temperature solenoid to be installed in a 10-foot long AGS straight section. This experiment will test the idea of using a partial snake to correct all depolarizing imperfection resonances and also test the feasibility of betatron tune jump in correction intrinsic resonances in the presence of a partial snake.

  10. Fabrication and test results of a high field, Nb3Sn superconducting racetrack dipole magnet

    SciTech Connect

    Benjegerdes, R.; Bish, P.; Byford, D.; Caspi, S.; Dietderich, D.R.; Gourlay, S.A.; Hafalia, R.; Hannaford, R.; Higley, H.; Jackson, A.; Lietzke, A.; Liggins, N.; McInturff, A.D.; O'Neill, J.; Palmerston, E.; Sabbi, G.; Scanlan, R.M.; Swanson, J.

    2001-06-15

    The LBNL Superconducting Magnet Program is extending accelerator magnet technology to the highest possible fields. A 1 meter long, racetrack dipole magnet, utilizing state-of-the-art Nb{sub 3}Sn superconductor, has been built and tested. A record dipole filed of 14.7 Tesla has been achieved. Relevant features of the final assembly and tested results are discussed.

  11. Energy politics

    NASA Astrophysics Data System (ADS)

    McEvoy, Augustin

    2012-07-01

    In his review of Tyler Hamilton's book Mad Like Tesla (May pp44-45), Roger Bridgman writes that "in energy supply, obviously, companies cannot simply junk huge infrastructure investments in favour of something new, however good it might be". But that is exactly what Angela Merkel's administration has done in Germany with its anti-nuclear policy.

  12. Wide-range nuclear magnetic resonance detector

    NASA Technical Reports Server (NTRS)

    Sturman, J. C.; Jirberg, R. J.

    1972-01-01

    Compact and easy to use solid state nuclear magnetic resonance detector is designed for measuring field strength to 20 teslas in cryogenically cooled magnets. Extremely low noise and high sensitivity make detector applicable to nearly all types of analytical nuclear magnetic resonance measurements and can be used in high temperature and radiation environments.

  13. Radio spectrum measurements of artificial ball lightning and testing the hypothesis on its plasmochemical nature

    NASA Astrophysics Data System (ADS)

    Kopeikin, V. V.

    2014-01-01

    Spectral measurements of radiowaves emitted by artificial ball lightning are presented. The measurements were carried out using two different facilities: a pulsed power generator (PPG) and a three-contour Tesla transformer. The results of these measurements confirm the hypothesis that ball lightning is a self-oscillator of high-voltage pulses in the radio range.

  14. The calibration of photographic and spectroscopic films: 1: A microscopic analysis of IIaO films. 2: The effects of agitation and soaking on IIaO films. 3: The effects of electric field on IIaO films. 4: The effects of X-ray radiation on IIaO films

    NASA Technical Reports Server (NTRS)

    Hammond, E. C., Jr.; Peters, K.; Boone, K.

    1978-01-01

    The grain structure of the emulsion using both reflected and transmission light was examined along with the effects of soaking. The effect of a static charge by a Tesla-coil, and the effects of airport equipment, and dental X-rays on the film were also analyzed.

  15. First Signal on the Cryogenic Fourier-Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Lin, Cheng; Mathur, Raman; Aizikov, Kostantin; O'Connor, Peter B.

    2009-01-01

    The construction and achievement of the first signal on a cryogenic Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) are reported here, demonstrating proof-of-concept of this new instrument design. Building the FTICR cell into the cold bore of a superconducting magnet provided advantages over conventional warm bore design. At 4.2 K, the vacuum system cryopumps itself, thus removing the requirement for a large bore to achieve the desired pumping speed for maintaining base pressure. Furthermore, because the bore diameter has been reduced, the amount of magnet wire needed to achieve high field and homogeneity was also reduced, greatly decreasing the cost/Tesla of the magnet. The current instrument implements an actively shielded 14-Tesla magnet of vertical design with an external matrix assisted laser desorption/ionization (MALDI) source. The first signal was obtained by detecting the laser desorbed/ionized (LDI) C60+• ions, with the magnet at 7 Tesla, unshimmed, and the preamplifier mounted outside of the vacuum chamber at room temperature. A subsequent experiment done with the magnet at 14 Tesla and properly shimmed produced a C60 spectrum showing ∼350,000 resolving power at m/z ∼720. Increased magnetic field strength improves many FTMS performance parameters simultaneously, particularly mass resolving power and accuracy. PMID:17931882

  16. A 12 coil superconducting bumpy torus magnet facility for plasma research

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

    1972-01-01

    A summary is presented of the performance of the two-coil superconducting pilot rig which preceded the NASA Lewis bumpy torus. This pilot rig was operated for 550 experimental runs over a period of 7 years. The NASA Lewis bumpy torus facility consists of 12 superconducting coils, each with a 19 cm in diameter and capable of producing magnetic field strengths of 3.0 teslas on their axes. The magnets are equally spaced around a major circumference 1.52 m in diameter, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.59 m in diameter. The design value of maximum magnetic field on the magnetic axis (3.0 teslas) was reached and exceeded. A maximum magnetic field of 3.23 teslas was held for a period of 60 minutes, and the coils did not go to normal. When the coils were charged to a maximum magnetic field of 3.35 teslas, the coil system was driven normal without damage to the facility.

  17. Performance of a 12-coil superconducting bumpy torus magnet facility

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

    1972-01-01

    The bumpy torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 teslas on their axes. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Final shakedown tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The facility is now ready for use as a plasma physics research facility. A maximum magnetic field on the magnetic axis of 3.23 teslas was held for a period of more than sixty minutes without a coil normalcy. The design field was 3.00 teslas. The steady-state liquid helium boil-off rate was 87 liters per hour of liquid helium without the coils charged. The coil array was stable when subjected to an impulsive loading, even with the magnets fully charged. When the coils were charged to a maximum magnetic field of 3.35 teslas, the system was driven normal without damage.

  18. Hydroglyphics: Demonstration of Selective Wetting on Hydrophilic and Hydrophobic Surfaces

    ERIC Educational Resources Information Center

    Kim, Philseok; Alvarenga, Jack; Aizenberg, Joanna; Sleeper, Raymond S.

    2013-01-01

    A visual demonstration of the difference between hydrophilic and hydrophobic surfaces has been developed. It involves placing a shadow mask on an optically clear hydrophobic plastic dish, corona treating the surface with a modified Tesla coil, removing the shadow mask, and visualizing the otherwise invisible message or pattern by applying water,…

  19. Efficacy in Microbial Sterilization of Pulsed Magnetic Field Treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sterilization effects of the pulsed magnetic field with a maximum intensity of 11.37 Tesla were investigated on Escherichia coli AS 1.129, Staphylococcus aureus AS 1.89, Saccharomyces cerevisiae ATTC 7552 and Bacillus subtilis AS 1.921. The well-regulated fluctuations of sterilization effects with m...

  20. Energy Loss and Energy Spread Growth in a Planar Undulator(LCC-0086)

    SciTech Connect

    Sheppard, J

    2003-10-07

    The change in beam energy spread due to transmission through a long, planar undulator is calculated. This change is shown to be gaussian as expected from the central limit theorem and large number of photons emitted per electron. These results are compared with Saldin et al. [2] expressions. Numerical results for the case of the TESLA beam and for an NLC beam are given.

  1. Science at 100 T

    SciTech Connect

    Harrison, Neil

    2012-06-01

    100 tesla fields are essential for answering many key questions in condensed matter: (1) Collapse of magnetic length crucial tool for understanding high Tc superconductors; (2) Field can also behave as 'negative pressure' in condensed matter; and (3) Field-tuned emergent phenomena involving commensurability effects.

  2. Neural Correlates of Metonymy Resolution

    ERIC Educational Resources Information Center

    Rapp, Alexander M.; Erb, Michael; Grodd, Wolfgang; Bartels, Mathias; Markert, Katja

    2011-01-01

    Metonymies are exemplary models for complex semantic association processes at the sentence level. We investigated processing of metonymies using event-related functional magnetic resonance imaging (fMRI). During an 1.5 Tesla fMRI scan, 14 healthy subjects (12 female) read 124 short German sentences with either literal (like "Africa is arid"),…

  3. Tuned cavity magnetometer sensitivity.

    SciTech Connect

    Okandan, Murat; Schwindt, Peter

    2009-09-01

    We have developed a high sensitivity (Tesla/{radical}Hz), non-cryogenic magnetometer that utilizes a novel optical (interferometric) detection technique. Further miniaturization and low-power operation are key advantages of this magnetometer, when compared to systems using SQUIDs which require liquid Helium temperatures and associated overhead to achieve similar sensitivity levels.

  4. Sec. Chu Announces the First Auto Loans for Advanced Technologies

    SciTech Connect

    Secretary Chu

    2009-07-16

    Energy Secretary Steven Chu announced $8 billion in conditional loan commitments for the development of innovative, advanced vehicle technologies that will create thousands of green jobs while helping reduce the nation’s dangerous dependence on foreign oil. The first three auto loans for advanced technologies were awarded to Ford Motor Company, Nissan Motors and Tesla Motors.

  5. Design and performance of a 30 KV electron gun with ten independent cathodes & a magnetic lens.

    SciTech Connect

    Rudys, Joseph Matthew; Reed, Kim Warren

    2006-08-01

    Measurements on a 30 kV electron gun with ten independent cathodes, operating in a 6.5 Tesla (T) magnetic field are presented. An earlier paper covered the design of this electron gun [1]. Experimental results are compared to model predictions. Beam current is compared to theoretical space charge limited flow.

  6. Accurate cortical tissue classification on MRI by modeling cortical folding patterns.

    PubMed

    Kim, Hosung; Caldairou, Benoit; Hwang, Ji-Wook; Mansi, Tommaso; Hong, Seok-Jun; Bernasconi, Neda; Bernasconi, Andrea

    2015-09-01

    Accurate tissue classification is a crucial prerequisite to MRI morphometry. Automated methods based on intensity histograms constructed from the entire volume are challenged by regional intensity variations due to local radiofrequency artifacts as well as disparities in tissue composition, laminar architecture and folding patterns. Current work proposes a novel anatomy-driven method in which parcels conforming cortical folding were regionally extracted from the brain. Each parcel is subsequently classified using nonparametric mean shift clustering. Evaluation was carried out on manually labeled images from two datasets acquired at 3.0 Tesla (n = 15) and 1.5 Tesla (n = 20). In both datasets, we observed high tissue classification accuracy of the proposed method (Dice index >97.6% at 3.0 Tesla, and >89.2% at 1.5 Tesla). Moreover, our method consistently outperformed state-of-the-art classification routines available in SPM8 and FSL-FAST, as well as a recently proposed local classifier that partitions the brain into cubes. Contour-based analyses localized more accurate white matter-gray matter (GM) interface classification of the proposed framework compared to the other algorithms, particularly in central and occipital cortices that generally display bright GM due to their highly degree of myelination. Excellent accuracy was maintained, even in the absence of correction for intensity inhomogeneity. The presented anatomy-driven local classification algorithm may significantly improve cortical boundary definition, with possible benefits for morphometric inference and biomarker discovery.

  7. Sec. Chu Announces the First Auto Loans for Advanced Technologies

    ScienceCinema

    Secretary Chu

    2016-07-12

    Energy Secretary Steven Chu announced $8 billion in conditional loan commitments for the development of innovative, advanced vehicle technologies that will create thousands of green jobs while helping reduce the nation’s dangerous dependence on foreign oil. The first three auto loans for advanced technologies were awarded to Ford Motor Company, Nissan Motors and Tesla Motors.

  8. Bridgman Growth of Germanium

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Volz, M. P.; Cobb, S. D.; Motakef, S.

    1997-01-01

    The high-magnetic-field crystal growth facility at the Marshall Space Flight Center will be briefly described. This facility has been used to grow bulk germanium by the Bridgman technique in magnetic fields up to 5 Tesla. The results of investigations of ampoule material on the interface shape and thermal field applied to the melt on stability against convection will be discussed.

  9. Using a Feature Film to Promote Scientific Enquiry

    ERIC Educational Resources Information Center

    Hadzigeorgiou, Yannis; Kodakos, Tassos; Garganourakis, Vassilios

    2010-01-01

    This article reports on an action research project undertaken with the primary aim of investigating the extent to which a feature film, whose plot included Tesla's demonstrations on the wireless transmission of electrical energy, can promote scientific enquiry. The class that participated in this project was an 11th grade class in a rural area of…

  10. Interaction Region Issues at the NLC

    SciTech Connect

    Markiewicz, Thomas W.; Maruyama, T.; /SLAC

    2007-09-26

    Two detector concepts are being investigated for the Next Linear Collider. This paper discusses the current design of the interaction region for one of them, based on a 6 Tesla solenoid and silicon based tracking. Topics include masking layout, backgrounds and the suppression of final quadrupole jitter. All calculations are based on the 1 TeV design parameters.

  11. Prediction of processing tomato peeling outcomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peeling outcomes of processing tomatoes were predicted using multivariate analysis of Magnetic Resonance (MR) images. Tomatoes were obtained from a whole-peel production line. Each fruit was imaged using a 7 Tesla MR system, and a multivariate data set was created from 28 different images. After ...

  12. First signal on the cryogenic Fourier-transform ion cyclotron resonance mass spectrometer.

    PubMed

    Lin, Cheng; Mathur, Raman; Aizikov, Kostantin; O'Connor, Peter B

    2007-12-01

    The construction and achievement of the first signal on a cryogenic Fourier-transform ion cyclotron resonance mass spectrometer (FTICR-MS) are reported here, demonstrating proof-of-concept of this new instrument design. Building the FTICR cell into the cold bore of a superconducting magnet provided advantages over conventional warm bore design. At 4.2 K, the vacuum system cryopumps itself, thus removing the requirement for a large bore to achieve the desired pumping speed for maintaining base pressure. Furthermore, because the bore diameter has been reduced, the amount of magnet wire needed to achieve high field and homogeneity was also reduced, greatly decreasing the cost/Tesla of the magnet. The current instrument implements an actively shielded 14-Tesla magnet of vertical design with an external matrix-assisted laser desorption/ionization (MALDI) source. The first signal was obtained by detecting the laser desorbed/ionized (LDI) C(60)(+*) ions, with the magnet at 7 Tesla, unshimmed, and the preamplifier mounted outside of the vacuum chamber at room temperature. A subsequent experiment done with the magnet at 14 Tesla and properly shimmed produced a C(60) spectrum showing approximately 350,000 resolving power at m/z approximately 720. Increased magnetic field strength improves many FTMS performance parameters simultaneously, particularly mass resolving power and accuracy.

  13. Magnetic field dependent photoluminescence studies of InGaAs/GaAs strained-single-quantum wells

    SciTech Connect

    Jones, E.D.; Dawson, L.R.; Klem, J.F.; Lyo, S.K.; Heiman, D.; Liu, X.C.

    1994-08-01

    Magnetoluminescence determined conduction-band and valence-band dispersion curves are presented for n-type InGaAs/GaAs stained-single-quantum well structures. The magnetic field range was 0 to 30 tesla, and the temperature varied between 4.2 and 77.4 K.

  14. J/Ψ production in two-photon collisions at next-to-leading order

    NASA Astrophysics Data System (ADS)

    Mihaila, L.

    2004-10-01

    In this paper, we report on the calculation of the cross section of J/Ψ plus jet inclusive production in direct γγ collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD). Theoretical predictions for the future e+e- linear collider TESLA are also presented.

  15. Tolerances of TTF-2 First Bunch Compressor

    SciTech Connect

    Emma, Paul J

    2003-08-08

    In bunch compressors for SASE-FEL facilities, the projected transverse emittance can be diluted by magnetic multipole component errors in dipoles and dipole misalignments as well as by coherent synchrotron radiation (CSR). In this paper, we describe the multipole field tolerances and the misalignment tolerances of the first bunch compressor (BC2) for the TESLA Test Facility Phase-2 (TTF-2).

  16. Accurate cortical tissue classification on MRI by modeling cortical folding patterns.

    PubMed

    Kim, Hosung; Caldairou, Benoit; Hwang, Ji-Wook; Mansi, Tommaso; Hong, Seok-Jun; Bernasconi, Neda; Bernasconi, Andrea

    2015-09-01

    Accurate tissue classification is a crucial prerequisite to MRI morphometry. Automated methods based on intensity histograms constructed from the entire volume are challenged by regional intensity variations due to local radiofrequency artifacts as well as disparities in tissue composition, laminar architecture and folding patterns. Current work proposes a novel anatomy-driven method in which parcels conforming cortical folding were regionally extracted from the brain. Each parcel is subsequently classified using nonparametric mean shift clustering. Evaluation was carried out on manually labeled images from two datasets acquired at 3.0 Tesla (n = 15) and 1.5 Tesla (n = 20). In both datasets, we observed high tissue classification accuracy of the proposed method (Dice index >97.6% at 3.0 Tesla, and >89.2% at 1.5 Tesla). Moreover, our method consistently outperformed state-of-the-art classification routines available in SPM8 and FSL-FAST, as well as a recently proposed local classifier that partitions the brain into cubes. Contour-based analyses localized more accurate white matter-gray matter (GM) interface classification of the proposed framework compared to the other algorithms, particularly in central and occipital cortices that generally display bright GM due to their highly degree of myelination. Excellent accuracy was maintained, even in the absence of correction for intensity inhomogeneity. The presented anatomy-driven local classification algorithm may significantly improve cortical boundary definition, with possible benefits for morphometric inference and biomarker discovery. PMID:26037453

  17. A comparison of FreeSurfer-generated data with and without manual intervention

    PubMed Central

    McCarthy, Christopher S.; Ramprashad, Avinash; Thompson, Carlie; Botti, Jo-Anna; Coman, Ioana L.; Kates, Wendy R.

    2015-01-01

    This paper examined whether FreeSurfer—generated data differed between a fully—automated, unedited pipeline and an edited pipeline that included the application of control points to correct errors in white matter segmentation. In a sample of 30 individuals, we compared the summary statistics of surface area, white matter volumes, and cortical thickness derived from edited and unedited datasets for the 34 regions of interest (ROIs) that FreeSurfer (FS) generates. To determine whether applying control points would alter the detection of significant differences between patient and typical groups, effect sizes between edited and unedited conditions in individuals with the genetic disorder, 22q11.2 deletion syndrome (22q11DS) were compared to neurotypical controls. Analyses were conducted with data that were generated from both a 1.5 tesla and a 3 tesla scanner. For 1.5 tesla data, mean area, volume, and thickness measures did not differ significantly between edited and unedited regions, with the exception of rostral anterior cingulate thickness, lateral orbitofrontal white matter, superior parietal white matter, and precentral gyral thickness. Results were similar for surface area and white matter volumes generated from the 3 tesla scanner. For cortical thickness measures however, seven edited ROI measures, primarily in frontal and temporal regions, differed significantly from their unedited counterparts, and three additional ROI measures approached significance. Mean effect sizes for edited ROIs did not differ from most unedited ROIs for either 1.5 or 3 tesla data. Taken together, these results suggest that although the application of control points may increase the validity of intensity normalization and, ultimately, segmentation, it may not affect the final, extracted metrics that FS generates. Potential exceptions to and limitations of these conclusions are discussed. PMID:26539075

  18. Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider

    SciTech Connect

    James T Volk et al.

    2001-09-24

    The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0-20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype.

  19. Magnetic resonance imaging without field cycling at less than earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

    2015-03-01

    A strong pre-polarization field, usually tenths of a milli-tesla in magnitude, is used to increase the signal-to-noise ratio in ordinary superconducting quantum interference device-based nuclear magnetic resonance/magnetic resonance imaging experiments. Here, we introduce an experimental approach using two techniques to remove the need for the pre-polarization field. A dynamic nuclear polarization (DNP) technique enables us to measure an enhanced resonance signal. In combination with a π / 2 pulse to avoid the Bloch-Siegert effect in a micro-tesla field, we obtained an enhanced magnetic resonance image by using DNP technique with a 34.5 μT static external magnetic field without field cycling. In this approach, the problems of eddy current and flux trapping in the superconducting pickup coil, both due to the strong pre-polarization field, become negligible.

  20. Performance of An Adjustable Strength Permanent Magnet Quadrupole

    SciTech Connect

    Gottschalk, S.C.; DeHart, T.E.; Kangas, K.W.; Spencer, C.M.; Volk, J.T.; /Fermilab

    2006-03-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic CL and field quality made using an air bearing rotating coil system. The magnetic CL stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic CL. Calibration procedures as well as CL measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.