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5578921 Magnetic resonance imaging using three-dimensional spectral-spatial excitation
xx
Patents ALERT
disposedin the first plane, adjacentto the first portion of the first loop and a secondportion substantially disposed in a third planeessentiallyparallel to and spacedfrom the secondplane. A method of using such RF coils is also disclosed.
5577504 MAGNETIC
RESONANCE
APPARATUS
Salloway Anthony J; Gilderdale David J Northamptonshire, UNITED KINGDOM assigned to GEC-Marconi Limited
5576622 SHIELDED NMR RADIO FREQUENCY COIL AND METHOD OF PERFORMING AN NMR EXPERIMENT Morrone Terry; Votruba Jan Greenlawn, NY, UNITED STATES assignedto Fonar Corporation An RF coil for NMR experiments having a conductive path for flowing a field-cancelling current to isolate magneticallythe RF coil from its environment.NMR data, particularly MRI data from a human subject, is collected with the receiver coil magnetically shieldedto avoid loss of the received signal energy to the environment.
5576623 GRADIENT
SYSTEM FOR AN NMR TOMOGRAPH
Muller Wolfgang Karlsruhe, GERMANY assignedto Bruker Analytische MesstechnikGmbH A gradient system for a nuclear spin resonance(NMR) tomograph with a main magnet system producing a homogeneousmagneticfield directedalonga z-axis inside a measuring volume, wherein the main magnet system provides accessto the measuringvolume along the z-axis and transversely to the z-axis, and wherein the gradient systemcomprisestwo first partial gradient systemswhich are located at opposite sides of a central plane perpendicularto the z-axis, acrossthe measuringvolume. At leastone of the two partial gradientsystemsis movable betweenat leasttwo positionsalong the z-axis. In this way, with a small constructional size and with a simple manufacturing procedure, a gradient system is obtained with high performancecapability with respectto generated gradientstrength for given ampereturns, high linearity of the generatedgradient fields, minimum inductance and minimum electrical resistanceof the conductor segments.
In a magnetic resonanceapparatus including an active noise reduction arrangement for use by a patient undergoing examination in the apparatusthe transducers of the arrangement are non-magnetic, e.g. are of the electret, piezoelectricor condensertype, and have no parts of ferromagnetic material.
5578920 COMPENSATION OF INTERFERING FIELDS IN NMR MEASUREMENTS IN THE EARTH’S MAGNETIC FIELD Kuster Anton; Laukien Dirk D Greifensee, SWITZERLAND assignedto SpectrospinAG In an apparatushaving at least one detection coil for the detection of nuclear magnetic resonance(NMR) from a sensitivity region of the detection coil in the ground, whereby nuclear spins within the sensitivity region are excited by repeatedcoherent excitation, in each case,to precessin the earth’s field and produce a small NMR induction voltage in the detectioncoil which is introduced to a first amplifier, the detection coil consistsof at least two oppositelywound partial coils having parallelcoil axes which are connectedelectrically in seriesand at leastone compensationcoil is provided for additionalcompensation of spatially inhomogeneous interfering fields whose induction signal is introducedto a secondamplifier having adjustableamplification. In this fashion, in addition to the homogeneousportion, an inhomogeneousportion due to distantdisturbancescan be eliminated from the measured signal.
5578921 MAGNETIC RESONANCE IMAGING USING THREE-DIMENSIONAL SPECTRAL-SPATIAL EXCITATION
Patents ALERT
Morrell Glen R Stanford, CA, UNITED STATES assignedto Board of Trustees of the Leland Stanford Junior University Using3-D spectral-spatialexcitation, the center frequency of the spectralpassbandcan be varied asa function of two spatial coordinates, Such variation could be tailored to field map data to compensatefor BO shifts. The 3-D excitation has3-D spiral trajectories in k-space.
5578922 METHOD OF CONTAINING IMAGES REPRESENTING THE DISTRIBUTION OF PARAMAGNETIC MATERIAL IN SOLUTION Lurie David J; Mallard John R; Nicholson la Cults, UNITED KINGDOM assignedto British Technology Group Limited PCT No. PCT/GB93/01652 Sec. 371 Date Feb. 3, 1995 Sec. 102(e) Date Feb. 3, i995 PCT Filed Aug. 5, 1993 PCT Pub.No. WO94/03824 PCT Pub. Date Feb. 17,1994. The invention provides a method of proton-electron double-resonance magneticresonanceimaging in which a samplecontainingparamagneticmaterial is subjectedto a polarizing magnetic field during a polarization period, a subsequentevolution period and thereafter a detection period, and the sampleis subjectedduring the evolution period to radio-frequency radiation, at a frequency appropriate to the polarizing magnetic field then appertaining, so as to excite EPR resonance in the paramagneticmaterial,whereinduring the detectionperiod the sampleis subjectedto a seriesof NMR interrogating signalsto derive therefrom a correspondingseriesof NMR imagesignalsfor combination in a completeNMR image. Preferably, the method according to the invention incorporates the technique of field cycling and the polarizing magnetic field is reduced from a first steady value during the polarization period to have a second, lower, value during the evolution period, being thereafter increasedto have a value greater than the secondvalue (and preferably equalto or lessthan the first value) during the detection period.
5578923
XXI
T2 RESTORATION AND NOISE SUPPRESSION OF HYBRID MR IMAGES USING WIENER AND LINEAR PREDICTION TECHNIQUES Chen Haiguan San Francisco, CA, UNITED STATES assignedto The Regentsof the University of California Hybrid imaging (HI) sequences used for magnetic resonance(MR) imaging and inherently degradedby T2 effects and additive measurementnoise are enhanced. Wiener filter and linear prediction (LP) technique is used to processHI MR signalsin the spatialfrequency domain (K-space) and the hybrid domain respectively. Basedon the averageamplitudesymmetry constraintof the spinecho signal, the amplitude frequency responsefunction of the T2 distortion is estimatedand usedin the Weiner filter for a global T2 amplituderestoration.Then a linear prediction technique is utilized to obtain local signal amplitude and phaseestimatesaround discontinuities of the frequency responsefunction of the equivalent T2 distortion filter. These estimatesare used to make local amplitude and phase corrections. The effectiveness of this combined technique in correction T2 distortion and reducing the measurementnoise is analyzed and demonstratedusing experimentson both phantomsand humans.
5578924 METHODS FOR THE SIMULTANEOUS DETECTION OF MULTIPLE MAGNETIC RESONANCE IMAGES Dumoulin CharlesL; Hardy ChristopherJ Ballston Lake, NY, UNITED STATES assignedto General Electric Company A multi-planar imaging method employs magnetic resonanceto detect imagedata from multiple planeswithin a subject.Data from eachplaneare detectedin responseto the samereadoutgradientand are simultaneouslydetected. The imageplanescan be arbitrarily oriented with respect to each other and with respect to the readout and phase-encodingimageformation magnetic field gradient pulsesif desired.Overlap of imagedata from each of the excited imageplanesin the acquiredimageis preventedby employing a thick refocusing slab oriented orthogonal to the readoutandphase-encoding directions, or by choosing planeswhich intersectoutsidethe subject’sanatomy.
Patents ALERT
disposedin the first plane, adjacentto the first portion of the first loop and a secondportion substantially disposed in a third planeessentiallyparallel to and spacedfrom the secondplane. A method of using such RF coils is also disclosed.
5577504 MAGNETIC
RESONANCE
APPARATUS
Salloway Anthony J; Gilderdale David J Northamptonshire, UNITED KINGDOM assigned to GEC-Marconi Limited
5576622 SHIELDED NMR RADIO FREQUENCY COIL AND METHOD OF PERFORMING AN NMR EXPERIMENT Morrone Terry; Votruba Jan Greenlawn, NY, UNITED STATES assignedto Fonar Corporation An RF coil for NMR experiments having a conductive path for flowing a field-cancelling current to isolate magneticallythe RF coil from its environment.NMR data, particularly MRI data from a human subject, is collected with the receiver coil magnetically shieldedto avoid loss of the received signal energy to the environment.
5576623 GRADIENT
SYSTEM FOR AN NMR TOMOGRAPH
Muller Wolfgang Karlsruhe, GERMANY assignedto Bruker Analytische MesstechnikGmbH A gradient system for a nuclear spin resonance(NMR) tomograph with a main magnet system producing a homogeneousmagneticfield directedalonga z-axis inside a measuring volume, wherein the main magnet system provides accessto the measuringvolume along the z-axis and transversely to the z-axis, and wherein the gradient systemcomprisestwo first partial gradient systemswhich are located at opposite sides of a central plane perpendicularto the z-axis, acrossthe measuringvolume. At leastone of the two partial gradientsystemsis movable betweenat leasttwo positionsalong the z-axis. In this way, with a small constructional size and with a simple manufacturing procedure, a gradient system is obtained with high performancecapability with respectto generated gradientstrength for given ampereturns, high linearity of the generatedgradient fields, minimum inductance and minimum electrical resistanceof the conductor segments.
In a magnetic resonanceapparatus including an active noise reduction arrangement for use by a patient undergoing examination in the apparatusthe transducers of the arrangement are non-magnetic, e.g. are of the electret, piezoelectricor condensertype, and have no parts of ferromagnetic material.
5578920 COMPENSATION OF INTERFERING FIELDS IN NMR MEASUREMENTS IN THE EARTH’S MAGNETIC FIELD Kuster Anton; Laukien Dirk D Greifensee, SWITZERLAND assignedto SpectrospinAG In an apparatushaving at least one detection coil for the detection of nuclear magnetic resonance(NMR) from a sensitivity region of the detection coil in the ground, whereby nuclear spins within the sensitivity region are excited by repeatedcoherent excitation, in each case,to precessin the earth’s field and produce a small NMR induction voltage in the detectioncoil which is introduced to a first amplifier, the detection coil consistsof at least two oppositelywound partial coils having parallelcoil axes which are connectedelectrically in seriesand at leastone compensationcoil is provided for additionalcompensation of spatially inhomogeneous interfering fields whose induction signal is introducedto a secondamplifier having adjustableamplification. In this fashion, in addition to the homogeneousportion, an inhomogeneousportion due to distantdisturbancescan be eliminated from the measured signal.
5578921 MAGNETIC RESONANCE IMAGING USING THREE-DIMENSIONAL SPECTRAL-SPATIAL EXCITATION
Patents ALERT
Morrell Glen R Stanford, CA, UNITED STATES assignedto Board of Trustees of the Leland Stanford Junior University Using3-D spectral-spatialexcitation, the center frequency of the spectralpassbandcan be varied asa function of two spatial coordinates, Such variation could be tailored to field map data to compensatefor BO shifts. The 3-D excitation has3-D spiral trajectories in k-space.
5578922 METHOD OF CONTAINING IMAGES REPRESENTING THE DISTRIBUTION OF PARAMAGNETIC MATERIAL IN SOLUTION Lurie David J; Mallard John R; Nicholson la Cults, UNITED KINGDOM assignedto British Technology Group Limited PCT No. PCT/GB93/01652 Sec. 371 Date Feb. 3, 1995 Sec. 102(e) Date Feb. 3, i995 PCT Filed Aug. 5, 1993 PCT Pub.No. WO94/03824 PCT Pub. Date Feb. 17,1994. The invention provides a method of proton-electron double-resonance magneticresonanceimaging in which a samplecontainingparamagneticmaterial is subjectedto a polarizing magnetic field during a polarization period, a subsequentevolution period and thereafter a detection period, and the sampleis subjectedduring the evolution period to radio-frequency radiation, at a frequency appropriate to the polarizing magnetic field then appertaining, so as to excite EPR resonance in the paramagneticmaterial,whereinduring the detectionperiod the sampleis subjectedto a seriesof NMR interrogating signalsto derive therefrom a correspondingseriesof NMR imagesignalsfor combination in a completeNMR image. Preferably, the method according to the invention incorporates the technique of field cycling and the polarizing magnetic field is reduced from a first steady value during the polarization period to have a second, lower, value during the evolution period, being thereafter increasedto have a value greater than the secondvalue (and preferably equalto or lessthan the first value) during the detection period.
5578923
XXI
T2 RESTORATION AND NOISE SUPPRESSION OF HYBRID MR IMAGES USING WIENER AND LINEAR PREDICTION TECHNIQUES Chen Haiguan San Francisco, CA, UNITED STATES assignedto The Regentsof the University of California Hybrid imaging (HI) sequences used for magnetic resonance(MR) imaging and inherently degradedby T2 effects and additive measurementnoise are enhanced. Wiener filter and linear prediction (LP) technique is used to processHI MR signalsin the spatialfrequency domain (K-space) and the hybrid domain respectively. Basedon the averageamplitudesymmetry constraintof the spinecho signal, the amplitude frequency responsefunction of the T2 distortion is estimatedand usedin the Weiner filter for a global T2 amplituderestoration.Then a linear prediction technique is utilized to obtain local signal amplitude and phaseestimatesaround discontinuities of the frequency responsefunction of the equivalent T2 distortion filter. These estimatesare used to make local amplitude and phase corrections. The effectiveness of this combined technique in correction T2 distortion and reducing the measurementnoise is analyzed and demonstratedusing experimentson both phantomsand humans.
5578924 METHODS FOR THE SIMULTANEOUS DETECTION OF MULTIPLE MAGNETIC RESONANCE IMAGES Dumoulin CharlesL; Hardy ChristopherJ Ballston Lake, NY, UNITED STATES assignedto General Electric Company A multi-planar imaging method employs magnetic resonanceto detect imagedata from multiple planeswithin a subject.Data from eachplaneare detectedin responseto the samereadoutgradientand are simultaneouslydetected. The imageplanescan be arbitrarily oriented with respect to each other and with respect to the readout and phase-encodingimageformation magnetic field gradient pulsesif desired.Overlap of imagedata from each of the excited imageplanesin the acquiredimageis preventedby employing a thick refocusing slab oriented orthogonal to the readoutandphase-encoding directions, or by choosing planeswhich intersectoutsidethe subject’sanatomy.