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WO2003062847A1 - Optimisation de l'homogeneite d'un champ magnetique passif a l'aide de cales passives - Google Patents

Optimisation de l'homogeneite d'un champ magnetique passif a l'aide de cales passives Download PDF

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Publication number
WO2003062847A1
WO2003062847A1 PCT/GB2003/000313 GB0300313W WO03062847A1 WO 2003062847 A1 WO2003062847 A1 WO 2003062847A1 GB 0300313 W GB0300313 W GB 0300313W WO 03062847 A1 WO03062847 A1 WO 03062847A1
Authority
WO
WIPO (PCT)
Prior art keywords
shim
subject
mouth
brain
passive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2003/000313
Other languages
English (en)
Inventor
James Wilson
Peter Jezzard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Medical Research Council
Original Assignee
Medical Research Council
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0201700A external-priority patent/GB0201700D0/en
Priority claimed from GB0224706A external-priority patent/GB0224706D0/en
Application filed by Medical Research Council filed Critical Medical Research Council
Publication of WO2003062847A1 publication Critical patent/WO2003062847A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/387—Compensation of inhomogeneities
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/4806—Functional imaging of brain activation

Definitions

  • the invention relates to a method of imaging samples, especially a human or animal body, and to apparatus for use in the method.
  • a magnetic field may be considered as substantially homogeneous, for the purposes of the present specification, if the flux density of the field over the region of the sample from which data is being acquired varies by less than 0.5ppm, preferably by less than 0.2ppm and most preferably by less than O.lppm.
  • the inventors have also found that insertion of a highly diamagnetic passive shim into the ear canal can reduce the magnetic field inhomogeneities which affect imaging of the inferior temporal lobe, which are believed to be caused, at least in part, by the mastoid air cells (predominantly) and (to a lesser extent) the external auditory canal.
  • the invention provides a passive shim positioning device, the positioning device comprising a passive shim of highly diamagnetic material, and means for positioning (and preferably retaining) the passive shim in a particular location relative to the subject.
  • the passive shim positioning device takes the form of one or more of the following: a gum shield, a bite bar, a headphone, an ear plug or ear plugs, or a frame for engagement with or attachment to a subject's head.
  • Figures 1-7 illustrate various numbers of image sections.
  • Figures 1 and 3 comprise images of 25 sections of the B0 map of a human brain in the axial plane with ( Figure 3) or without ( Figure 1) a passive shim of highly diamagnetic material.
  • Figures 2 and 4-7 show MRI sections of the human brain in the axial plane with (Figs. 4 and 7) or without (Figs. 2, 5 and 6) a highly diamagnetic passive shim;
  • the simulated B 0 distribution arising from the mouth shim alone is shown in Figure 17.
  • the large B 0 lobe superior to the shim overlaps with the IFC B 0 inhomogeneity while the smaller lateral B 0 lobe impinges negligibly on the inferior portions of the brain.
  • Residual large-scale B 0 variations present in the brain are removed through subsequent active shimming using first and second order room temperature shim coils.
  • Figure 22 shows the simulation results when considering fluctuations in the spatial derivative of the magnetic field in the slice direction (G z ).
  • the range is -0.4ppm/cm to 0.4ppm/cm.

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

Cette invention concerne un procédé permettant d'obtenir des données de résonance magnétique pour un échantillon. Ce procédé consiste à: (a) placer l'échantillon dans un champ magnétique approprié à flux de forte intensité, lequel champ est sensiblement homogène avant l'introduction de l'échantillon, échantillon dont la présence provoque elle-même des pertes d'homogénéité locales dans le champ magnétique; et b) placer contre l'échantillon une cale passive renfermant une quantité suffisante d'une substance fortement diamagnétique pour atténuer la perte d'homogénéité causée par l'échantillon dans le champ magnétique.
PCT/GB2003/000313 2002-01-25 2003-01-27 Optimisation de l'homogeneite d'un champ magnetique passif a l'aide de cales passives Ceased WO2003062847A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB0201700A GB0201700D0 (en) 2002-01-25 2002-01-25 Improvements in or relating to imaging
GB0201700.2 2002-01-25
GB0224706A GB0224706D0 (en) 2002-10-24 2002-10-24 Improvements in or relating to imaging
GB0224706.2 2002-10-24

Publications (1)

Publication Number Publication Date
WO2003062847A1 true WO2003062847A1 (fr) 2003-07-31

Family

ID=27614801

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/000313 Ceased WO2003062847A1 (fr) 2002-01-25 2003-01-27 Optimisation de l'homogeneite d'un champ magnetique passif a l'aide de cales passives

Country Status (1)

Country Link
WO (1) WO2003062847A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007084399A3 (fr) * 2006-01-13 2007-11-29 Univ Yale Procédés et appareil de compensation d'homogénéités de champ dans des études sur la résonance magnétique
WO2008114195A3 (fr) * 2007-03-20 2008-11-20 Koninkl Philips Electronics Nv Récepteur radio pour système d'imagerie par résonance magnétique

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1444781A (fr) * 1964-05-07 1966-07-08 Scott Paper Co Nouvelles structures polymérisées, constituées au moins en partie par un matériau polyoléfinique
US5111146A (en) * 1989-05-31 1992-05-05 U.S. Philips Corporation Coil system for volume-selective magnetic resonance spectroscopy
US5173661A (en) * 1989-11-08 1992-12-22 Bruker Analytische Mebtechnik Gmbh Nuclear magnetic resonance spectrometer
US5339033A (en) * 1992-08-11 1994-08-16 Alliance Pharmaceutical Corp. Method of improving fat saturation during MRI
US6294972B1 (en) * 2000-08-03 2001-09-25 The Mcw Research Foundation, Inc. Method for shimming a static magnetic field in a local MRI coil

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1444781A (fr) * 1964-05-07 1966-07-08 Scott Paper Co Nouvelles structures polymérisées, constituées au moins en partie par un matériau polyoléfinique
US5111146A (en) * 1989-05-31 1992-05-05 U.S. Philips Corporation Coil system for volume-selective magnetic resonance spectroscopy
US5173661A (en) * 1989-11-08 1992-12-22 Bruker Analytische Mebtechnik Gmbh Nuclear magnetic resonance spectrometer
US5339033A (en) * 1992-08-11 1994-08-16 Alliance Pharmaceutical Corp. Method of improving fat saturation during MRI
US6294972B1 (en) * 2000-08-03 2001-09-25 The Mcw Research Foundation, Inc. Method for shimming a static magnetic field in a local MRI coil

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JESMANOWICZ A. ET AL: "Local Ferroshims Using Office Copier Toner", PROCEEDINGS OF THE INTERNATIONAL SOCIETY FOR MAGNETIC RESONANCE IN MEDICINE, 9TH SCIENTIFIC MEETING AND EXHIBITION, vol. 1, 21 April 2001 (2001-04-21), Glasgow, Scotland, pages 617, XP002237881 *
WILSON J L ET AL: "OPTIMIZATION OF STATIC FIELD HOMOGENEITY IN HUMAN BRAIN USING DIAMAGNETIC PASSIVE SHIMS", MAGNETIC RESONANCE IN MEDICINE, ACADEMIC PRESS, DULUTH, MN, US, vol. 48, no. 5, November 2002 (2002-11-01), pages 906 - 914, XP001130533, ISSN: 0740-3194 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007084399A3 (fr) * 2006-01-13 2007-11-29 Univ Yale Procédés et appareil de compensation d'homogénéités de champ dans des études sur la résonance magnétique
US8035387B2 (en) 2006-01-13 2011-10-11 Yale University Methods and apparatus for compensating field inhomogeneities in magnetic resonance studies
WO2008114195A3 (fr) * 2007-03-20 2008-11-20 Koninkl Philips Electronics Nv Récepteur radio pour système d'imagerie par résonance magnétique

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