NL192222C - Werkwijze en inrichting voor nucleaire magnetische resonantie. - Google Patents

Werkwijze en inrichting voor nucleaire magnetische resonantie. Download PDF

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Publication number
NL192222C
NL192222C NL7713926A NL7713926A NL192222C NL 192222 C NL192222 C NL 192222C NL 7713926 A NL7713926 A NL 7713926A NL 7713926 A NL7713926 A NL 7713926A NL 192222 C NL192222 C NL 192222C
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NL
Netherlands
Prior art keywords
gradient
axis
superimposed
magnetic field
field
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Application number
NL7713926A
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English (en)
Dutch (nl)
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NL7713926A (nl
NL192222B (nl
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British Tech Group
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Publication of NL7713926A publication Critical patent/NL7713926A/xx
Publication of NL192222B publication Critical patent/NL192222B/xx
Application granted granted Critical
Publication of NL192222C publication Critical patent/NL192222C/nl

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48NMR imaging systems
    • G01R33/54Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48NMR imaging systems
    • G01R33/54Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5615Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00Arrangements or instruments for measuring magnetic variables
    • G01R33/20Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48NMR imaging systems
    • G01R33/54Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5615Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
    • G01R33/5616Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE] using gradient refocusing, e.g. EPI

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
NL7713926A 1976-12-15 1977-12-15 Werkwijze en inrichting voor nucleaire magnetische resonantie. NL192222C (nl)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB52322/76A GB1596160A (en) 1976-12-15 1976-12-15 Nuclear magnetic resonance apparatus and methods
GB5232276 1976-12-15

Publications (3)

Publication Number Publication Date
NL7713926A NL7713926A (nl) 1978-06-19
NL192222B NL192222B (nl) 1996-11-01
NL192222C true NL192222C (nl) 1997-03-04

Family

ID=10463495

Family Applications (1)

Application Number Title Priority Date Filing Date
NL7713926A NL192222C (nl) 1976-12-15 1977-12-15 Werkwijze en inrichting voor nucleaire magnetische resonantie.

Country Status (5)

Country Link
US (1) US4165479A (ja)
JP (1) JPS6042906B2 (ja)
DE (1) DE2755956C2 (ja)
GB (1) GB1596160A (ja)
NL (1) NL192222C (ja)

Families Citing this family (100)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1584949A (en) * 1978-05-25 1981-02-18 Emi Ltd Imaging systems
USRE33259E (en) * 1978-07-20 1990-07-10 The Regents Of The University Of California Method and apparatus for rapid NMR imaging of nuclear parameters with an object
US4471305A (en) * 1978-07-20 1984-09-11 The Regents Of The University Of Calif. Method and apparatus for rapid NMR imaging of nuclear parameters with an object
US4354499A (en) * 1978-11-20 1982-10-19 Damadian Raymond V Apparatus and method for nuclear magnetic resonance scanning and mapping
DE2854774A1 (de) * 1978-12-19 1980-07-10 Battelle Institut E V Vorrichtung zur noninvasiven, lokalen in-vivo-untersuchung von koerpergewebe, organen, knochen, nerven oder von stroemendem blut auf der basis der spin-echo-technik
US4318044A (en) * 1979-03-07 1982-03-02 National Research Development Corporation Methods of indicating nuclear spin density distribution
NL7904986A (nl) * 1979-06-27 1980-12-30 Philips Nv Werkwijze en inrichting voor het bepalen van een kernspindichtheidsverdeling in een deel van een lichaam.
JPS5922825Y2 (ja) * 1979-07-03 1984-07-07 伝 斎藤 上下筋兼用スペ−サ
USRE32712E (en) * 1979-08-20 1988-07-12 General Electric Company Moving gradient zeugmatography
US4307343A (en) * 1979-08-20 1981-12-22 General Electric Company Moving gradient zeugmatography
FR2475282B1 (fr) 1980-02-05 1985-10-04 Radiologie Cie Gle Systeme de bobines electromagnetiques pour l'examen de corps volumineux par resonance magnetique nucleaire, et appareil d'imagerie du corps humain utilisant un tel systeme
WO1981002789A1 (en) * 1980-03-14 1981-10-01 Nat Res Dev Methods of producing image information from objects
JPS6051056B2 (ja) * 1980-06-13 1985-11-12 株式会社東芝 核磁気共鳴装置
CA1184602A (en) * 1981-01-26 1985-03-26 National Research Development Corporation Investigation of samples by n.m.r. techniques
US4408161A (en) * 1981-04-15 1983-10-04 Chevron Research Company Computer-controlled, portable spin echo NMR instrument and method of use
US4412179A (en) * 1981-04-15 1983-10-25 Chevron Research Company Computer-controlled, portable pulsed NMR instrument and method of use wherein the times of RF interrogation are distributed over at least a cycle at the nuclear magnetization precessional frequency
DE3123493A1 (de) * 1981-06-13 1982-12-30 Bruker Analytische Meßtechnik GmbH, 7512 Rheinstetten Elektromagnet fuer die nmr-tomographie
DE3131946A1 (de) * 1981-08-12 1983-03-17 Siemens AG, 1000 Berlin und 8000 München "hochfrequenz-magnetsystem in einer einrichtung der kernspinresonanz-technik"
DE3133933A1 (de) * 1981-08-27 1983-03-17 Siemens AG, 1000 Berlin und 8000 München "gradientenspulen-system einer einrichtung der kernspinresonanz-technik"
EP0076054B1 (en) * 1981-09-21 1986-06-04 Peter Mansfield Nuclear magnetic resonance methods
US4446429A (en) * 1981-10-09 1984-05-01 Medical College Of Wisconsin Microwave resonator
US4599565A (en) * 1981-12-15 1986-07-08 The Regents Of The University Of Calif. Method and apparatus for rapid NMR imaging using multi-dimensional reconstruction techniques
US4456881A (en) * 1982-01-18 1984-06-26 Technicare Corporation Gradient-coil apparatus for a magnetic resonance system
US4471306A (en) * 1982-02-03 1984-09-11 General Electric Company Method of NMR imaging which overcomes T2 * effects in an inhomogeneous static magnetic field
DE3219832A1 (de) * 1982-05-26 1983-12-01 Bruker Medizintechnik Gmbh, 7512 Rheinstetten Verfahren zur nicht-invasiven ermittlung von messwerten innerhalb eines lebenden koerpers
NL8203519A (nl) * 1982-09-10 1984-04-02 Philips Nv Werkwijze en inrichting voor het bepalen van een kernmagnetisatieverdeling in een deel van een lichaam.
DE3378848D1 (en) * 1982-10-06 1989-02-09 Peter Mansfield Nuclear magnetic resonance methods
JPS59105548A (ja) * 1982-12-09 1984-06-18 Yokogawa Hokushin Electric Corp 核磁気共鳴による検査方法及び検査装置
DE3245945A1 (de) * 1982-12-11 1984-06-14 Bruker Analytische Meßtechnik GmbH, 7512 Rheinstetten Elektromagnet fuer die nmr-tomographie
DE3245944A1 (de) * 1982-12-11 1984-06-14 Bruker Analytische Meßtechnik GmbH, 7512 Rheinstetten Elektromagnet fuer die nmr-tomographie
US4558278A (en) * 1982-12-17 1985-12-10 Picker International, Limited Nuclear magnetic resonance methods and apparatus
DE3301630A1 (de) * 1983-01-19 1984-07-19 Siemens AG, 1000 Berlin und 8000 München Geraet zur erzeugung von bildern eines untersuchungsobjektes
IL68344A (en) * 1983-04-10 1988-10-31 Yeda Res & Dev Method to eliminate the effects of magnetic field inhomogeneities in nmr imaging
JPS59200947A (ja) * 1983-04-30 1984-11-14 Toshiba Corp Mri装置における静磁場強度調整方法
US4639671A (en) * 1983-05-31 1987-01-27 General Electric Company Simultaneous NMR imaging system
GB8320653D0 (en) * 1983-08-01 1983-09-01 Eastwood L M Producing images by nmr techniques
GB8321295D0 (en) * 1983-08-08 1983-09-07 Redpath T W T Magnetic coils
GB8321308D0 (en) * 1983-08-08 1983-09-07 M & D Technology Ltd Radio frequency coil
US4617516A (en) * 1983-09-06 1986-10-14 General Electric Company Axial magnetic field gradient coil suitable for use with NMR apparatus
US4840700A (en) * 1983-11-02 1989-06-20 General Electric Company Current streamline method for coil construction
US4646024A (en) * 1983-11-02 1987-02-24 General Electric Company Transverse gradient field coils for nuclear magnetic resonance imaging
US4692705A (en) * 1983-12-23 1987-09-08 General Electric Company Radio frequency field coil for NMR
US4628264A (en) * 1984-03-14 1986-12-09 Advanced Nmr Systems, Inc. NMR gradient field modulation
FI73321C (fi) * 1984-06-07 1987-09-10 Instrumentarium Oy Foerfarande foer kartlaeggning av de kaernmagnetiska egenskaperna hos ett undersoekningsobjekt.
JPS61745A (ja) * 1984-06-13 1986-01-06 Toshiba Corp 核磁気共鳴装置
EP0165610B2 (en) * 1984-06-20 1992-11-11 Hitachi, Ltd. High speed imaging method with three-dimensional nmr
NL8402959A (nl) * 1984-09-28 1986-04-16 Philips Nv Snelle werkwijze en inrichting voor het bepalen van een kernmagnetisatieverdeling in een deel van een lichaam.
IL74942A (en) * 1984-10-22 1988-11-30 Univ Leland Stanford Junior Flow measurement using nuclear magnetic resonance
FI75428C (fi) * 1984-11-21 1988-06-09 Instrumentarium Oy Foerfarande foer kartlaeggning av de kaernmagnetiska egenskaperna hos ett objekt, som skall undersoekas.
DE3504734C2 (de) * 1985-02-12 1998-12-10 Max Planck Gesellschaft Verfahren und Vorrichtung zur Aufnahme von Spinresonanzdaten
US4651096A (en) * 1985-02-19 1987-03-17 Resonex Imaging method for nuclear magnetic resonance utilizing balanced gradient fields
US4668915A (en) * 1985-03-15 1987-05-26 Honda Giken Kogyo Kabushiki Kaisha Non-uniform field magnetic resonance dual patient imaging system
GB8508154D0 (en) * 1985-03-28 1985-05-01 Turner R Reconstruction of nuclear magnetic resonance images
US4678996A (en) * 1985-05-07 1987-07-07 Picker International, Inc. Magnetic resonance imaging method
US4788500A (en) * 1985-08-14 1988-11-29 Brigham & Women's Hospital Measurement of capillary flow using nuclear magnetic resonance
IL79691A0 (en) * 1985-08-14 1986-11-30 Brigham & Womens Hospital Measurement of capillary flow using nuclear magnetic resonance
US4689560A (en) * 1985-08-16 1987-08-25 Picker International, Inc. Low R.F. dosage magnetic resonance imaging of high velocity flows
US4769603A (en) * 1985-08-19 1988-09-06 Siemens Aktiengesellschaft Method for the operation of a nuclear magnetic resonance apparatus
GB8530930D0 (en) * 1985-12-16 1986-01-29 Mansfield P Inductive circuit arrangements
DE3604280A1 (de) * 1986-02-12 1987-08-13 Philips Patentverwaltung Verfahren zur bestimmung der raeumlichen und der spektralen verteilung der kernmagnetisierung in einem untersuchungsbereich und anordnung zur durchfuehrung des verfahrens
JPH0763455B2 (ja) * 1986-03-31 1995-07-12 株式会社東芝 磁気共鳴映像装置
US4740748A (en) * 1986-12-03 1988-04-26 Advanced Nmr Systems, Inc. Method of high-speed magnetic resonance imaging
US4862086A (en) * 1987-04-28 1989-08-29 Kabushiki Kaisha Toshiba System for generating magnetic fields utilized for magnetic resonance imaging apparatus
JP2558727B2 (ja) * 1987-08-25 1996-11-27 株式会社東芝 磁気共鳴診断装置
JP2642362B2 (ja) * 1987-09-30 1997-08-20 株式会社東芝 磁気共鳴映像装置
EP0325461A3 (en) * 1988-01-22 1990-08-16 Kabushiki Kaisha Toshiba Magnetic resonance imaging system
JP2646627B2 (ja) * 1988-03-08 1997-08-27 株式会社日立製作所 核磁気共鳴を用いた検査装置
GB2221995B (en) * 1988-08-19 1992-12-09 Picker Int Ltd Magnetic resonance methods and apparatus
US4947121A (en) * 1988-08-19 1990-08-07 General Electric Company Apparatus and method for enhanced multiple coil nuclear magnetic resonance (NMR) imaging
US4926125A (en) * 1988-08-22 1990-05-15 General Electric Company Surface gradient assembly for high speed nuclear magnetic resonance imaging
JP2777155B2 (ja) * 1988-11-30 1998-07-16 株式会社東芝 磁気共鳴映像装置
GB8909270D0 (en) * 1989-04-24 1989-06-07 Hafslund Nycomed Innovation Method
DE4014220A1 (de) * 1989-05-16 1990-11-22 Siemens Ag Entfaltung der uebertragungsfunktion bei der bilderzeugung mittels kernmagnetischer resonanz
GB8915090D0 (en) * 1989-06-30 1989-08-23 Cottrell Stephen P Nuclear magnetic resonance imaging methods
DE4005675C2 (de) * 1990-02-22 1995-06-29 Siemens Ag Verfahren zur Unterdrückung von Artefakten bei der Bilderzeugung mittels kernmagnetischer Resonanz
JPH03268742A (ja) * 1990-03-19 1991-11-29 Hitachi Ltd イメージング装置
JPH04136713U (ja) * 1991-06-10 1992-12-18 多摩川精機株式会社 操作レバー装置
US5568051A (en) * 1992-05-12 1996-10-22 Kabushiki Kaisha Toshiba Magnetic resonance imaging apparatus having superimposed gradient coil
US5323113A (en) * 1993-03-12 1994-06-21 Bruker Instruments, Inc. NMR probe which includes B1, gradient coils
US5554929A (en) * 1993-03-12 1996-09-10 Doty Scientific, Inc. Crescent gradient coils
US5530355A (en) * 1993-05-13 1996-06-25 Doty Scientific, Inc. Solenoidal, octopolar, transverse gradient coils
DE4432575C2 (de) * 1993-09-14 2003-04-10 Toshiba Kawasaki Kk Verfahren zur Bildgebung der Gehirnfunktion mittels einer Kernspinresonanz-Vorrichtung und hieran angepasste Kernspinresonanz-Vorrichtung
GB2295020B (en) * 1994-11-03 1999-05-19 Elscint Ltd Modular whole - body gradient coil
DE4445782C1 (de) * 1994-12-21 1996-07-25 Siemens Ag Verfahren zur Phasenkorrektur von Kernresonanzsignalen
JP2760330B2 (ja) * 1995-11-29 1998-05-28 株式会社日立製作所 核磁気共鳴を用いた検査装置
DE19606090C2 (de) * 1996-02-19 1998-01-22 Siemens Ag Verfahren zur funktionellen Bildgebung mittels magnetischer Resonanz
DE19715113C2 (de) * 1997-04-11 1999-01-28 Siemens Ag Verfahren zur Phasenkorrektur von Kernresonanzsignalen
US6043652A (en) * 1997-04-17 2000-03-28 Picker International, Inc. Alternative reconstruction method for non-equidistant k-space data
JP2908380B2 (ja) * 1997-05-14 1999-06-21 株式会社日立製作所 核磁気共鳴を用いた検査装置
US6219571B1 (en) * 1998-04-06 2001-04-17 Board Of Trustees Of The Leland Stanford Junior University Magnetic resonance imaging using driven equilibrium fourier transform
DE19937065C1 (de) 1999-08-05 2001-03-08 Siemens Ag Vorrichtung und Verfahren zur Stimulationsunterdrückung bei Magnetresonanztomographiegeräten
US20040075434A1 (en) * 2002-10-16 2004-04-22 Vavrek Robert Michael Gradient coil apparatus for magnetic resonance imaging
DE10325562B4 (de) * 2003-06-05 2009-10-01 Siemens Ag Steady-State-Pulssequenz mit verbesserter Unterdrückung von Inflow-effekten sowie Magnetresonanzgerät zur Durchführung dieses Verfahrens
US7641052B2 (en) * 2004-11-01 2010-01-05 Mattel, Inc. Display packaging for an animated toy
US8093896B2 (en) * 2006-09-21 2012-01-10 Massachusetts Institute Of Technology Uniform magnetic field spherical coil for MRI
EP2247253A4 (en) 2008-02-22 2015-08-05 Univ Loma Linda Med SYSTEMS AND METHODS FOR CHARACTERIZING SPATIAL DISTORTION OF 3D IMAGING SYSTEMS
JP4966994B2 (ja) * 2009-04-14 2012-07-04 国土交通省四国地方整備局長 基礎杭及び杭基礎の構造
US8669533B2 (en) 2009-10-01 2014-03-11 Vladimir Bashkirov Ion induced impact ionization detector and uses thereof
KR101050372B1 (ko) 2009-12-08 2011-07-21 한국표준과학연구원 외부자기 교란을 최소화한 △e 측정장치
US10064589B2 (en) 2014-06-27 2018-09-04 General Electric Company Method, apparatus, and article for pet attenuation correction utilizing MRI

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49103693A (ja) * 1973-02-02 1974-10-01
GB1508438A (en) * 1974-04-05 1978-04-26 Nat Res Dev Analysis of materials
US4021726A (en) * 1974-09-11 1977-05-03 National Research Development Corporation Image formation using nuclear magnetic resonance
CA1052861A (en) * 1975-03-18 1979-04-17 Varian Associates Gyromagnetic resonance fourier transform zeugmatography

Also Published As

Publication number Publication date
US4165479A (en) 1979-08-21
DE2755956C2 (de) 1987-04-16
NL7713926A (nl) 1978-06-19
DE2755956A1 (de) 1978-06-22
GB1596160A (en) 1981-08-19
JPS5381288A (en) 1978-07-18
NL192222B (nl) 1996-11-01
JPS6042906B2 (ja) 1985-09-25

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