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5245282 Three-dimensional magnetic resonance imaging
New Patents
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5243289 MULTIPLY-TUNED PROBE FOR MAGNETIC RESONANCE IMAGING OR SPECTROSCOPY Haywood Blum, Matthew D Mitchell assigned to The Trustees of the University of Pennsylvania A multiply-tuned probe for magnetic resonance imaging or !spectroscopy in which a !driving inductor is separately coupled to two or more trap inductors. The impedance match at each frequency is adjusted independently of the impedance match at the other frequencies and independent of the tuning by using a novel coil geometry with no overcoupling. In a preferred embodiment, a triple-tuned probe has a first inductor Ll disposed in a first plane and tuned to a first resonant frequency and a second inductor L2 disposed in a second plane parallel to the first plane and tuned to a second resonant frequency. A driving and receiving primary inductor Lp is disposed in a third plane parallel to the first and second planes and placed with respect to the first and second inductors Ll and L2 such that mutual inductance between Ll and Lp in between L2 and Lp is adjustable in accordance with the positions of the inductors Ll, L2 and Lp. A sample surface inductor Ls tuned to a third resonant frequency provides the third frequency. Mutual inductance between Ll and Lp in between L2 and Lp is changed by repositioning the inductors Ll, L2 and Lp to vary the amount of overlap between the cross-sections of the primary inductor Lp and the circular coils Ll, L2 and the distances between inductors Ll and Lp and between inductors L2 and Lp. Since each inductive coupling adds another variable to the probe circuit, more and easier ways are provided for adjusting the tuning and impedance matching.
5245280 MAGNETIC RESONANCE MAGNETOMETER WITH MULTIPLEXED EXCITING WINDINGS Mar Beranger, Nelly Kernevez, Jean-Michel Leger, Frederic Stoeckel, Meylan, France assigned to Commissariat a 1’Energie Atomique A magnetometer having three trirectangular trihedron windings (20x, 2Oy, 202) which are put
into service successively by a multiplexer (50). The means frequency (Fm) of the three measurement signals is independent of the orientation of the weak magnetic field which is to be measured.
5245281 NMR IMAGING METHOD Noriaki Yamada, Susumu Kosugi,’ Toru Shimazaki, Makoto Miyazaki, Tokyo, Japan assigned to Yokogawa Medical Systems Limited An NMR imaging method for imaging with isotropic pixel resolution and a short scan time by applying a non-square scan matrix matched to the sectional shape of a subject, wherein a non-square scan matrix is set with different vertical and horizontal dimensions corresponding to the sectional form of a subject and scan data is collected under two-dimensional Fourier transformation by setting the longer sides of the matrix in the direction of projection and the shorter sides in the warp direction, while simultaneously displaying an image in a non-square image matrix wherein a length corresponds to projection width A on one side and whose length corresponds to M/N time of projection width A (where M: number of view, N: number of sample in the direction of projection, and M(N) on the other.
5245282 THREE-DIMENSIONAL MAGNETIC RESONANCE IMAGING John P Mugler, James R Brookeman assigned to University of Virginia Alumni Patents Foundation A new three-dimensional (3D) MR imaging pulse sequence can produce over 100 highresolution, high-contrast images in as little as 6 minutes of imaging time. Without additional imaging time, this same image data can be postprocessed to yield high-resolution, high-contrast images in any arbitrary orientation. Thus, this new pulse sequence technique provides detailed yet comprehensive coverage. The method of this invention relates to a preparation-acquisition recovery sequence cycle. The first step is magnetization preparation (MP) period. The MP period can emply a series of RF pulses, gradient field pulses, and/or time delays to encode the
New Patents
desired contrast properties in the form of longitudinal magnetization. A data acquisition period includes at least two repetitions of a gradient echo sequence to acquire data for a fraction of k-space. A magnetization recovery period is provided which allows Tl and T2 relaxation before the start of the next sequence cycle. The MP, data acquisition and magnetization recovery steps are repeated until a predetermined k-space volume is sampled.
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of the invention, the conventional CPMAS experiment is performed with the proton decoupling RF applying at a frequency slightly different than the proton resonance frequency in order to suppress methylene (CH2) resonances more severely than CH and CH3 resonances. In another embodiment of the invention the RF pulse sequence normally using during the crosspolarization period is replaced with a WIM RF pulse sequence which has the effect of suppressing the CH and CH3 resonances, thereby leaving the CH2 resonances.
5245283 TECHNIQUE FOR SHIFTING OUT-OF-SLICE ARTIFACTS TO THE EDGE OF THE FIELD OF VIEW Terrence J Provost, Kenneth Foster assigned to Picker International Inc A magnetic resonance imaging sequence (FIG. 2 ) is applied with a phase encode gradient (60) between an RF excitation pulse (50) and a refocusing pulse (54) such that out-of-slice artifacts are collapsed into a single line or column (64) in a resultant image display (38). A digital radio frequency transmitter (20) adds an adjustable RF phase component (70) to the excitation pulse and digital radio frequency receiver (26) adds the inverse or negative of the phase component (72) to a received magnetic resonance echo (56). The RF phase increment is adjusted such that the artifact line is displayed at the edge or other selected portion of the resultant image away from a region (74) of primary interest. An operator control (80) enables the field of view to be shifted in the phase encode direction to view different portions of the patient along the phase encode axis. As the field of view is translated, the RF phase increment is adjusted correspondingly and the reconstructed image representation is rebinned (82) such that the artifact line remains at the edge of the image display.
5245284 METHOD FOR EDITING CPMAS SOLID-STATE NMR SPECTRA Douglas Burum, Anthony J Bielecki assigned to Bruker Instruments Inc A normal CPMAS experiment is modified to provide for spectral editing. In one embodiment
5245285 PROBE FOR MAGNETIC RESONANCE INSPECTION APPARATUS Toshihiro Ishizuka, Munetaka Tsuda, Masao Yabusaki, Yasuo Wada, Takayuki Shimizu, Katsuta, Japan assigned to Hitachi Ltd A quadrature detection device for magnetic resonance imaging includes a pair of probes each having a pair of first conductors with a vertical arm and wings formed at both ends of the vertical arm and guard rings disposed inside the wings to oppose them and predetermined capacitors. In each probe, the resonance characteristics of the probe has two peaks. Symmetry of the peak existing in the resonance frequency range is effected by spacing the peak existing in a frequency range other than the resonance frequency range apart from the former. Thus, uniformity of the resulting image can be improved. The drop of the Q value of the probe is prevented by shifting the former peak to a higher frequency range than the latter peak. Also, electric symmetry of the probe is maintained.
5245287 NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY APPARATUS HAVING A RESONANT CIRCUIT FOR GENERATING GRADIENT FIELDS Stefan Nowak, Franz Schmitt, Braeuningshof/Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A nuclear magnetic resonance tomography apparatus has at least one gradient coil interconnected with a capacitor to form a resonant
XVI
5243289 MULTIPLY-TUNED PROBE FOR MAGNETIC RESONANCE IMAGING OR SPECTROSCOPY Haywood Blum, Matthew D Mitchell assigned to The Trustees of the University of Pennsylvania A multiply-tuned probe for magnetic resonance imaging or !spectroscopy in which a !driving inductor is separately coupled to two or more trap inductors. The impedance match at each frequency is adjusted independently of the impedance match at the other frequencies and independent of the tuning by using a novel coil geometry with no overcoupling. In a preferred embodiment, a triple-tuned probe has a first inductor Ll disposed in a first plane and tuned to a first resonant frequency and a second inductor L2 disposed in a second plane parallel to the first plane and tuned to a second resonant frequency. A driving and receiving primary inductor Lp is disposed in a third plane parallel to the first and second planes and placed with respect to the first and second inductors Ll and L2 such that mutual inductance between Ll and Lp in between L2 and Lp is adjustable in accordance with the positions of the inductors Ll, L2 and Lp. A sample surface inductor Ls tuned to a third resonant frequency provides the third frequency. Mutual inductance between Ll and Lp in between L2 and Lp is changed by repositioning the inductors Ll, L2 and Lp to vary the amount of overlap between the cross-sections of the primary inductor Lp and the circular coils Ll, L2 and the distances between inductors Ll and Lp and between inductors L2 and Lp. Since each inductive coupling adds another variable to the probe circuit, more and easier ways are provided for adjusting the tuning and impedance matching.
5245280 MAGNETIC RESONANCE MAGNETOMETER WITH MULTIPLEXED EXCITING WINDINGS Mar Beranger, Nelly Kernevez, Jean-Michel Leger, Frederic Stoeckel, Meylan, France assigned to Commissariat a 1’Energie Atomique A magnetometer having three trirectangular trihedron windings (20x, 2Oy, 202) which are put
into service successively by a multiplexer (50). The means frequency (Fm) of the three measurement signals is independent of the orientation of the weak magnetic field which is to be measured.
5245281 NMR IMAGING METHOD Noriaki Yamada, Susumu Kosugi,’ Toru Shimazaki, Makoto Miyazaki, Tokyo, Japan assigned to Yokogawa Medical Systems Limited An NMR imaging method for imaging with isotropic pixel resolution and a short scan time by applying a non-square scan matrix matched to the sectional shape of a subject, wherein a non-square scan matrix is set with different vertical and horizontal dimensions corresponding to the sectional form of a subject and scan data is collected under two-dimensional Fourier transformation by setting the longer sides of the matrix in the direction of projection and the shorter sides in the warp direction, while simultaneously displaying an image in a non-square image matrix wherein a length corresponds to projection width A on one side and whose length corresponds to M/N time of projection width A (where M: number of view, N: number of sample in the direction of projection, and M(N) on the other.
5245282 THREE-DIMENSIONAL MAGNETIC RESONANCE IMAGING John P Mugler, James R Brookeman assigned to University of Virginia Alumni Patents Foundation A new three-dimensional (3D) MR imaging pulse sequence can produce over 100 highresolution, high-contrast images in as little as 6 minutes of imaging time. Without additional imaging time, this same image data can be postprocessed to yield high-resolution, high-contrast images in any arbitrary orientation. Thus, this new pulse sequence technique provides detailed yet comprehensive coverage. The method of this invention relates to a preparation-acquisition recovery sequence cycle. The first step is magnetization preparation (MP) period. The MP period can emply a series of RF pulses, gradient field pulses, and/or time delays to encode the
New Patents
desired contrast properties in the form of longitudinal magnetization. A data acquisition period includes at least two repetitions of a gradient echo sequence to acquire data for a fraction of k-space. A magnetization recovery period is provided which allows Tl and T2 relaxation before the start of the next sequence cycle. The MP, data acquisition and magnetization recovery steps are repeated until a predetermined k-space volume is sampled.
XVII
of the invention, the conventional CPMAS experiment is performed with the proton decoupling RF applying at a frequency slightly different than the proton resonance frequency in order to suppress methylene (CH2) resonances more severely than CH and CH3 resonances. In another embodiment of the invention the RF pulse sequence normally using during the crosspolarization period is replaced with a WIM RF pulse sequence which has the effect of suppressing the CH and CH3 resonances, thereby leaving the CH2 resonances.
5245283 TECHNIQUE FOR SHIFTING OUT-OF-SLICE ARTIFACTS TO THE EDGE OF THE FIELD OF VIEW Terrence J Provost, Kenneth Foster assigned to Picker International Inc A magnetic resonance imaging sequence (FIG. 2 ) is applied with a phase encode gradient (60) between an RF excitation pulse (50) and a refocusing pulse (54) such that out-of-slice artifacts are collapsed into a single line or column (64) in a resultant image display (38). A digital radio frequency transmitter (20) adds an adjustable RF phase component (70) to the excitation pulse and digital radio frequency receiver (26) adds the inverse or negative of the phase component (72) to a received magnetic resonance echo (56). The RF phase increment is adjusted such that the artifact line is displayed at the edge or other selected portion of the resultant image away from a region (74) of primary interest. An operator control (80) enables the field of view to be shifted in the phase encode direction to view different portions of the patient along the phase encode axis. As the field of view is translated, the RF phase increment is adjusted correspondingly and the reconstructed image representation is rebinned (82) such that the artifact line remains at the edge of the image display.
5245284 METHOD FOR EDITING CPMAS SOLID-STATE NMR SPECTRA Douglas Burum, Anthony J Bielecki assigned to Bruker Instruments Inc A normal CPMAS experiment is modified to provide for spectral editing. In one embodiment
5245285 PROBE FOR MAGNETIC RESONANCE INSPECTION APPARATUS Toshihiro Ishizuka, Munetaka Tsuda, Masao Yabusaki, Yasuo Wada, Takayuki Shimizu, Katsuta, Japan assigned to Hitachi Ltd A quadrature detection device for magnetic resonance imaging includes a pair of probes each having a pair of first conductors with a vertical arm and wings formed at both ends of the vertical arm and guard rings disposed inside the wings to oppose them and predetermined capacitors. In each probe, the resonance characteristics of the probe has two peaks. Symmetry of the peak existing in the resonance frequency range is effected by spacing the peak existing in a frequency range other than the resonance frequency range apart from the former. Thus, uniformity of the resulting image can be improved. The drop of the Q value of the probe is prevented by shifting the former peak to a higher frequency range than the latter peak. Also, electric symmetry of the probe is maintained.
5245287 NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY APPARATUS HAVING A RESONANT CIRCUIT FOR GENERATING GRADIENT FIELDS Stefan Nowak, Franz Schmitt, Braeuningshof/Erlangen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft A nuclear magnetic resonance tomography apparatus has at least one gradient coil interconnected with a capacitor to form a resonant