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4647858 Methods for overcoming transient magnetic field inhomogeneity in nuclear magnetic resonance imaging
VIII
New Patents
ject to be inspected is adapted to be inserted in the cylindrical magnetic flux conductor. A cylindrical magnet apparatus comparatively light in weight which has a homogeneous magnetic field and has magnetic shielding effect and is suitable for routine applications is thus provided.
4647857 FLOW MEASUREMENT USING NUCLEAR MAGNETIC RESONANCE Michael sity
4644473 CORRECTION CIRCUIT FOR A STATIC MAGNETIC FIELD OF AN NMR APPARATUS AND NMR APPARATUS FOR UTILIZING THE SAME Fumitosh Ootawara, Toshiba
Kojima, Masahiko Hatanaka, Japan assigned to Kabushiki Kaisha
In the NMR apparatus the resonant conditions may be kept constant by adjusting the strength of the static magnetic field. The echo signal that is induced under the specific conditions is processed so as to obtain the deviation of the resonant frequency in the correction circuit. The shift of the given static magnetic field is calculated based upon the deviation of the resonant frequency. The DC energizing current for the HO power supply is varied based upon the magnetic field shift so as to maintain the NMR phenomenon at the desirable resonant conditions.
4647447 DIAGNOSTIC
MEDIA
Heinz Gries, Douw Rosenberg, Hanns-Joachim Weinmann, Berlin, Federal Republic Of Germany assigned to Schering Aktiengesellschaft A diagnostic medium contains at least one physiologically well tolerated complex salt comprising an anion of a complexing acid and one or more central ion or ions of an element with an atomic number of 21 to 29,42,44 or 57 to 83 and, optionally, one or more physiologically biocompatible cation or cations of an inorganic and/or organic base or amino acid, optionally, with additives customary in galenic formulations, dissolved or suspended in an aqueous medium.
A Taber
assigned
to Stanford
Univer-
A modified spin echo sequence is employed to identify fluid movement in a material. The volume of interest is subjected to a static field along one axis (Z) and an RF magnetic excitation pulse transverse to the static field is applied which tilts the nuclear spins in the volume. The tilted nuclear spins are then allowed to precess about the uniform static field in the presence of a gradient field whereby the nuclear spins become dephased. Thereafter, a spin echo of the static spins is created by either a 180&20 + 0 RF pulse or reversal of the gradient field. Upon refocusing of the static nuclear spins a restoration RF pulse is applied to realign the stationary nuclear spins with the static field. Nuclear spins undergoing bulk motion as in fluid flow will be refocused to a different phase than the stationary spins so that the final RF pulse will in general leave these spins with a non-zero transverse magnetic moment. This residual transverse magnetic moment is then detected to identify the fluid movement.
4647858 METHODS FOR OVERCOMING TRANSIENT MAGNETIC FIELD INHOMOGENEITY IN NUCLEAR MAGNETIC RESONANCE IMAGING Paul Bottomley Company
assigned
to General
Electric
Methods for overcoming transient magnetic field gradient inhomogeneity in a nuclear magnetic resonance imaging and/or nuclear magnetic resonance spectroscopic imaging system, wherein the inhomogeneities are induced by the pulsed magnetic field gradients utilized in the imaging process itself, provide at least one correction pulse signal during, or after, any application of the desired magnetic field to the sampleto-be-investigated in the system. At least one of the pulse signal characteristics is adjusted to oppose and substantially cancel an error-producing portion of the total magnetic field gradient in a particular direction. The magnetic field gradient correction signal(s) can be applied: during a non-
IX
New Patents
selective RF pulse; immediately subsequent to an initial gradient field application (either alone or coincident with a selective 180&20 +0 RF pulse); during acquisition of response signal data; or at any time to correct for inter-gradient cross-talk conditions.
8700922 CARDIAC AND RESPIRATORY GATED MAGNETIC RESONANCE IMAGING Douglas M BLAKELEY, Carolyn A KERSHAW, Raymond E M D GANGAROSA assigned to PICKER INTERNATIONAL INC;
8700637 MAGNETIC RESONANCE ANALYSIS OF SUBSTANCES IN SAMPLES THAT INCLUDE DISSIPATIVE MATERIAL Howard J HALPERN, Howard J HALPERN assigned to PRESIDENT AND FELLOWS OF HARVARD COLLEGE Magnetic resonance images of the distribution of a substance within a sample are obtained by splaying a pair of magnetic field generating coils (40, 42) relative to each other to generate a magnetic field gradient along an axis of the sample. In other aspects, electron spin resonance data is derived from animal tissue, or images are derived from a sample that includes dissipative material, using a radio frequency signal of sufficiently low frequency.
8700921 INTERFACE SYSTEM FOR NMR SPECTROMETER AND QUADRATURE PROBE George J MISIC, George J MISIC assigned PICKER INTERNATIONAL INC;
A magnetic resonance imaging apparatus (A) generates a uniform main magnetic field, gradient fields transversely thereacross, excites resonance in nuclei within an image region, receives radio frequency signals from the resonating nuclei, and reconstructs images representative thereof. Electrodes (30) monitor the cardiac cycle of a patient (B) being imaged and an expansible belt (32) monitors the respiratory cycle. A carrier signal from a generator (52) is modulated with the respiratory signals. The modulated carrier signals are combined (60) with the cardiac signals and converted to a light signal by a light source (62). A fiber optic cable (36) conducts the light signals to a light receiver (70). Band pass filters (72, 100) separate the received cardiac and respiratory encoded carrier signals. A zero detector (80) provides a scan initiation signal in response to a preselected portion of the cardiac cycle. The respiratory encoded carrier signal is demodulated by demodulator (102) and a comparator (116) blocks or enables the processing of image data during a selected window of the respiratory cycle. A window adjustment means (118) adjusts the respiratory window as a function of phase encoding of the resonating nuclei.
8700924 to
An interface for interfacing a transmitter (C), a receiver (F) and a common probe assembly, for example in a magnetic resonance spectrometer comprising a first RF switch (10) for selectively passing and blocking the passage of RF signals between the transmitter and a first probe port (30); a phase shift means (20) connected between the first probe port and a second probe port (34) a second RF switch (40) for selectively passing and blocking the passage of RF signals between the second probe port and the receiver; and control means (G) which operates the RF switches so that when one blocks RF signals, the other passes RF signals and vice versa.
IMPROVED MAGNETIC RESONANCE RECONSTRUCTION AND SCANNING TECHNIQUES USING KNOWN INFORMATION, CONSTRAINTS, AND SYMMETRY RELATIONS Mark E HAACKE, Mark E HAACKE assigned to PICKER INTERNATIONAL INC; A reference object (24) is disposed in an image region (20) with a subject (22) to be examined. The reference object has known parameters such as relaxation time, spin density, dimensions, and position. Magnetic resonance signals in which the spatial position of resonating nuclei is encoded in the relative phase and frequency
New Patents
ject to be inspected is adapted to be inserted in the cylindrical magnetic flux conductor. A cylindrical magnet apparatus comparatively light in weight which has a homogeneous magnetic field and has magnetic shielding effect and is suitable for routine applications is thus provided.
4647857 FLOW MEASUREMENT USING NUCLEAR MAGNETIC RESONANCE Michael sity
4644473 CORRECTION CIRCUIT FOR A STATIC MAGNETIC FIELD OF AN NMR APPARATUS AND NMR APPARATUS FOR UTILIZING THE SAME Fumitosh Ootawara, Toshiba
Kojima, Masahiko Hatanaka, Japan assigned to Kabushiki Kaisha
In the NMR apparatus the resonant conditions may be kept constant by adjusting the strength of the static magnetic field. The echo signal that is induced under the specific conditions is processed so as to obtain the deviation of the resonant frequency in the correction circuit. The shift of the given static magnetic field is calculated based upon the deviation of the resonant frequency. The DC energizing current for the HO power supply is varied based upon the magnetic field shift so as to maintain the NMR phenomenon at the desirable resonant conditions.
4647447 DIAGNOSTIC
MEDIA
Heinz Gries, Douw Rosenberg, Hanns-Joachim Weinmann, Berlin, Federal Republic Of Germany assigned to Schering Aktiengesellschaft A diagnostic medium contains at least one physiologically well tolerated complex salt comprising an anion of a complexing acid and one or more central ion or ions of an element with an atomic number of 21 to 29,42,44 or 57 to 83 and, optionally, one or more physiologically biocompatible cation or cations of an inorganic and/or organic base or amino acid, optionally, with additives customary in galenic formulations, dissolved or suspended in an aqueous medium.
A Taber
assigned
to Stanford
Univer-
A modified spin echo sequence is employed to identify fluid movement in a material. The volume of interest is subjected to a static field along one axis (Z) and an RF magnetic excitation pulse transverse to the static field is applied which tilts the nuclear spins in the volume. The tilted nuclear spins are then allowed to precess about the uniform static field in the presence of a gradient field whereby the nuclear spins become dephased. Thereafter, a spin echo of the static spins is created by either a 180&20 + 0 RF pulse or reversal of the gradient field. Upon refocusing of the static nuclear spins a restoration RF pulse is applied to realign the stationary nuclear spins with the static field. Nuclear spins undergoing bulk motion as in fluid flow will be refocused to a different phase than the stationary spins so that the final RF pulse will in general leave these spins with a non-zero transverse magnetic moment. This residual transverse magnetic moment is then detected to identify the fluid movement.
4647858 METHODS FOR OVERCOMING TRANSIENT MAGNETIC FIELD INHOMOGENEITY IN NUCLEAR MAGNETIC RESONANCE IMAGING Paul Bottomley Company
assigned
to General
Electric
Methods for overcoming transient magnetic field gradient inhomogeneity in a nuclear magnetic resonance imaging and/or nuclear magnetic resonance spectroscopic imaging system, wherein the inhomogeneities are induced by the pulsed magnetic field gradients utilized in the imaging process itself, provide at least one correction pulse signal during, or after, any application of the desired magnetic field to the sampleto-be-investigated in the system. At least one of the pulse signal characteristics is adjusted to oppose and substantially cancel an error-producing portion of the total magnetic field gradient in a particular direction. The magnetic field gradient correction signal(s) can be applied: during a non-
IX
New Patents
selective RF pulse; immediately subsequent to an initial gradient field application (either alone or coincident with a selective 180&20 +0 RF pulse); during acquisition of response signal data; or at any time to correct for inter-gradient cross-talk conditions.
8700922 CARDIAC AND RESPIRATORY GATED MAGNETIC RESONANCE IMAGING Douglas M BLAKELEY, Carolyn A KERSHAW, Raymond E M D GANGAROSA assigned to PICKER INTERNATIONAL INC;
8700637 MAGNETIC RESONANCE ANALYSIS OF SUBSTANCES IN SAMPLES THAT INCLUDE DISSIPATIVE MATERIAL Howard J HALPERN, Howard J HALPERN assigned to PRESIDENT AND FELLOWS OF HARVARD COLLEGE Magnetic resonance images of the distribution of a substance within a sample are obtained by splaying a pair of magnetic field generating coils (40, 42) relative to each other to generate a magnetic field gradient along an axis of the sample. In other aspects, electron spin resonance data is derived from animal tissue, or images are derived from a sample that includes dissipative material, using a radio frequency signal of sufficiently low frequency.
8700921 INTERFACE SYSTEM FOR NMR SPECTROMETER AND QUADRATURE PROBE George J MISIC, George J MISIC assigned PICKER INTERNATIONAL INC;
A magnetic resonance imaging apparatus (A) generates a uniform main magnetic field, gradient fields transversely thereacross, excites resonance in nuclei within an image region, receives radio frequency signals from the resonating nuclei, and reconstructs images representative thereof. Electrodes (30) monitor the cardiac cycle of a patient (B) being imaged and an expansible belt (32) monitors the respiratory cycle. A carrier signal from a generator (52) is modulated with the respiratory signals. The modulated carrier signals are combined (60) with the cardiac signals and converted to a light signal by a light source (62). A fiber optic cable (36) conducts the light signals to a light receiver (70). Band pass filters (72, 100) separate the received cardiac and respiratory encoded carrier signals. A zero detector (80) provides a scan initiation signal in response to a preselected portion of the cardiac cycle. The respiratory encoded carrier signal is demodulated by demodulator (102) and a comparator (116) blocks or enables the processing of image data during a selected window of the respiratory cycle. A window adjustment means (118) adjusts the respiratory window as a function of phase encoding of the resonating nuclei.
8700924 to
An interface for interfacing a transmitter (C), a receiver (F) and a common probe assembly, for example in a magnetic resonance spectrometer comprising a first RF switch (10) for selectively passing and blocking the passage of RF signals between the transmitter and a first probe port (30); a phase shift means (20) connected between the first probe port and a second probe port (34) a second RF switch (40) for selectively passing and blocking the passage of RF signals between the second probe port and the receiver; and control means (G) which operates the RF switches so that when one blocks RF signals, the other passes RF signals and vice versa.
IMPROVED MAGNETIC RESONANCE RECONSTRUCTION AND SCANNING TECHNIQUES USING KNOWN INFORMATION, CONSTRAINTS, AND SYMMETRY RELATIONS Mark E HAACKE, Mark E HAACKE assigned to PICKER INTERNATIONAL INC; A reference object (24) is disposed in an image region (20) with a subject (22) to be examined. The reference object has known parameters such as relaxation time, spin density, dimensions, and position. Magnetic resonance signals in which the spatial position of resonating nuclei is encoded in the relative phase and frequency