NMR in Biomedicine

Cover image for NMR in Biomedicine

Special Issue: Radiofrequency Coils

November 2009

Volume 22, Issue 9

Pages 907–1001

Issue edited by: T. Vaughan

  1. Editorials

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Editorial (page 907)

      J. Thomas Vaughan Jr.

      Article first published online: 23 OCT 2009 | DOI: 10.1002/nbm.1459

  2. Review Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
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      The development of the birdcage resonator: a historical perspective (pages 908–918)

      Cecil E. Hayes

      Article first published online: 23 OCT 2009 | DOI: 10.1002/nbm.1431

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      A personal account of the development of the birdcage resonator covers the historic context of early MRI development, the critical role of RF coil technology in high field imaging, the need for an RF shield, the importance of distributed capacitance, the scientific controversies over magnetic field strength for imaging, a comparison of the birdcage design to an earlier Technicare phased coil, the distribution of electric fields in birdcage resonators, and the limitations of birdcages at very high fields.

  3. Research Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Numerical field calculations considering the human subject for engineering and safety assurance in MRI (pages 919–926)

      Christopher M. Collins

      Article first published online: 3 APR 2008 | DOI: 10.1002/nbm.1251

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      Numerical calculations of static, switched, and radiofrequency (RF) electromagnetic (EM) fields considering the geometry and EM properties of the human body are used increasingly in MRI for a variety of purposes. Here some fundamental principles are reviewed and current approaches and applications are catalogued to aid the reader in finding resources valuable in beginning field calculations for their own applications in MRI.

    2. Understanding and manipulating the RF fields at high field MRI (pages 927–936)

      Tamer S. Ibrahim, Yik-Kiong Hue and Lin Tang

      Article first published online: 17 JUL 2009 | DOI: 10.1002/nbm.1406

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      The paper presents an overview of ‘What happens, in terms of electromagnetics, when operating at different static MRI field strengths?’ Using experimental studies and numerical simulations, this paper examines how electromagnetic quantities can be manipulated in order to advance MRI at high field strengths. Pertinent to this subject, this paper also presents the first experimental phantom work for B1 shimming without B1 measurements.

  4. Review Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Hybrid numerical techniques for the modelling of radiofrequency coils in MRI (pages 937–951)

      Bing Keong Li, Feng Liu, Ewald Weber and Stuart Crozier

      Article first published online: 16 DEC 2008 | DOI: 10.1002/nbm.1344

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      Numerical modelling is the preferred method for MRI RF coil design. This review article looks specifically at hybridisation of FDTD, FEM and MoM methods and how they are integrated to form versatile modelling techniques. Using several test cases to compare the numerical results obtained from these hybrid methods with experimental results, a high level of accuracy can be observed. Hybrid numerical methods can therefore provide a useful aid for the design and optimisation of MRI RF coils.

  5. Research Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Improving SNR of RF coils using composite coil elements (pages 952–959)

      Zhiyue J. Wang

      Article first published online: 6 JUL 2009 | DOI: 10.1002/nbm.1410

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      Computer simulations compared the SNR of a single-loop coil with that of a composite coil element where up to two additional orthogonal loops were included. The SNR of coil arrays employing single or composite elements was also evaluated. Results: the composite coil element has a substantially better SNR than that of a single-loop element covering the same surface area. The SNR of a composite element is insensitive to the surface orientation relative to B0.

    2. High-field head radiofrequency volume coils using transverse electromagnetic (TEM) and phased array technologies (pages 960–974)

      Nikolai I. Avdievich and Hoby P. Hetherington

      Article first published online: 23 JUN 2008 | DOI: 10.1002/nbm.1262

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      This article describes advances in high-field head RF volume coils using TEM and phased array technologies. It includes a new method to optimize the RF field distribution from multi-element coils using real time measurements of the RF current in the coil elements. The work also describes different techniques for simultaneous use of transmit TEM volume coils in combination with various phased arrays for SNR and homogeneity improvement.

  6. Review Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Radiofrequency coils for magnetic resonance microscopy (pages 975–981)

      Thomas Neuberger and Andrew Webb

      Article first published online: 26 FEB 2008 | DOI: 10.1002/nbm.1246

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      MR microscopy requires specialized RF coils to obtaining high spatial resolution within reasonable data acquisition times. For samples much less than 1 mm in size, wire solenoids or microfabricated planar coils have been developed. For samples with diameters of several millimeters, miniature birdcage or millipede coils become the preferred geometry. Multiple-coil probes, phased arrays and superconducting coils have all been constructed to reduce data acquisition time and/or increase sample throughput.

  7. Research Articles

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness
    1. Single echo acquisition MRI using RF encoding (pages 982–993)

      Steven M. Wright and Mary Preston McDougall

      Article first published online: 13 MAY 2009 | DOI: 10.1002/nbm.1399

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      Single echo acquisition (SEA) imaging performs spatial encoding using a one-dimensional array of RF coils, eliminating phase encoding and enabling MR movies at ultra-fast frame rates. Phase encoding is replaced with a single “phase compensation” pulse to counteract the phase cancellation in individual voxels caused by the receive coil sensitivity pattern. As RF encoding is not a time-integral effect, SEA imaging provides an extremely fast “shutter speed” which may have application in imaging of turbulent flow or other non-periodic behavior.

  8. Current Awareness

    1. Top of page
    2. Editorials
    3. Review Articles
    4. Research Articles
    5. Review Articles
    6. Research Articles
    7. Review Articles
    8. Research Articles
    9. Current Awareness

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