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4706030 Waveform generator for nuclear magnetic resonance apparatus
New Patents
predetermined relationship between the object motion and the adjustable parameter of the magnetic field gradient. The relationship is chosen to minimize artifacts in the reconstructed to various image. The method is applicable NMR imaging techniques, including Fourier Transform and multiple angle projection reconstruction.
VII
of a sample disposed in a magnetostatic field. Then, phase disorder in a direction of a first field gradient due to the first step is compensated for and at least one 180 degrees RF pulse is applied. Next, the nuclear spin is again excited in the slice plane, after which at least first, second and third magnetic field gradients are applied to derive an output signal.
4706027
4706030
METHOD FOR CORRECTING PHASE ERRORS IN MAGNETIC RESONANCE IMAGING DATA
WAVEFORM GENERATOR FOR NUCLEAR MAGNETIC RESONANCE APPARATUS
Simon H Hughes Toshiba
assigned
to Kabushiki
Kaisha
A two dimensional Fourier transform magnetic resonance imaging method produces a series of scan lines in Fourier space using quadrature demodulation of a series of radio frequency echo signals from an object being observed with a reference signal. Fourier transforming the scan line data provides visual image data through a section of the object. Limitations in the hardware performance introduces unknown, time varying, phase errors into the scan line data, proportional to the phase difference between the reference signal and the echo signals as each is demodulated. Improved visual imaging results from the introduction of an additional sensitive line scan through Y = 0 in Fourier space, having a calculable phase error which is used to correct the unknown phase errors in the remaining scan lines. The phase term of the sensitive line data is corrected for the phase error which is known at Y =O. Magnetic resonance imaging scan line data are next generated for a slice through the object. Because the phase of the sum of the data for each scan line must be the same as that of the sensitive line data for corresponding values of Y, the scan line phase error may be calculated and removed from the phase of each scan line.
4706028 NMR IMAGING METHOD Kiyoshi Yoda, Hidenob Itagaki, Satosh Fujimura, Hyogo, Japan assigned to Mitsubishi Denki Kabushiki Kaisha A method of imaging flowing fluids, such as human blood, using nuclear magnetic resonance whereby an image of high resolution is obtained. First, nuclear spin is excited in a given slice plane
Reginald A Willard, William S Percival, Middlesex, United Kingdom assigned to National Research Development Corporation Nuclear magnetic resonance is excited in surrounding fluids by pulsing a first winding which with a capacitor forms a resonant circuit. In order to observe signals induced by NMR in the first winding between pulses, the pulses are given an envelope which rises linearly to a peak and then immediately decays linearly to zero. A waveform generator generates bursts of constant amplitude oscillations having a 180 degrees phase change at the centre of each burst. When such bursts are applied to the resonant circuit by way of a drive amplifier and a second winding wound over the first winding, the required envelope is generated in the first winding.
4706057 MAGNET OF A NUCLEAR SPIN TOMOGRAPH August Schwab, Berlin, Federal Germany assigned to Siemens lschaft
Republic Of Aktiengesel-
A magnet of permanent magnet material for use in a nuclear spin tomograph has a longitudinally extending cavity for receiving a patent, the cavity and the outer contour of the magnet being substantially rectangular. The magnet comprises simple prismatic parts which are assembled unmagnetized. Upon assembly, the magnet is magnetized so that an approximately homogeneous magnetic field prevails in the cavity and the space outside the magnet is approximately free of fields. Magnetically soft plates are disposed on the inside surfaces of two horizontal legs of the magnet.
predetermined relationship between the object motion and the adjustable parameter of the magnetic field gradient. The relationship is chosen to minimize artifacts in the reconstructed to various image. The method is applicable NMR imaging techniques, including Fourier Transform and multiple angle projection reconstruction.
VII
of a sample disposed in a magnetostatic field. Then, phase disorder in a direction of a first field gradient due to the first step is compensated for and at least one 180 degrees RF pulse is applied. Next, the nuclear spin is again excited in the slice plane, after which at least first, second and third magnetic field gradients are applied to derive an output signal.
4706027
4706030
METHOD FOR CORRECTING PHASE ERRORS IN MAGNETIC RESONANCE IMAGING DATA
WAVEFORM GENERATOR FOR NUCLEAR MAGNETIC RESONANCE APPARATUS
Simon H Hughes Toshiba
assigned
to Kabushiki
Kaisha
A two dimensional Fourier transform magnetic resonance imaging method produces a series of scan lines in Fourier space using quadrature demodulation of a series of radio frequency echo signals from an object being observed with a reference signal. Fourier transforming the scan line data provides visual image data through a section of the object. Limitations in the hardware performance introduces unknown, time varying, phase errors into the scan line data, proportional to the phase difference between the reference signal and the echo signals as each is demodulated. Improved visual imaging results from the introduction of an additional sensitive line scan through Y = 0 in Fourier space, having a calculable phase error which is used to correct the unknown phase errors in the remaining scan lines. The phase term of the sensitive line data is corrected for the phase error which is known at Y =O. Magnetic resonance imaging scan line data are next generated for a slice through the object. Because the phase of the sum of the data for each scan line must be the same as that of the sensitive line data for corresponding values of Y, the scan line phase error may be calculated and removed from the phase of each scan line.
4706028 NMR IMAGING METHOD Kiyoshi Yoda, Hidenob Itagaki, Satosh Fujimura, Hyogo, Japan assigned to Mitsubishi Denki Kabushiki Kaisha A method of imaging flowing fluids, such as human blood, using nuclear magnetic resonance whereby an image of high resolution is obtained. First, nuclear spin is excited in a given slice plane
Reginald A Willard, William S Percival, Middlesex, United Kingdom assigned to National Research Development Corporation Nuclear magnetic resonance is excited in surrounding fluids by pulsing a first winding which with a capacitor forms a resonant circuit. In order to observe signals induced by NMR in the first winding between pulses, the pulses are given an envelope which rises linearly to a peak and then immediately decays linearly to zero. A waveform generator generates bursts of constant amplitude oscillations having a 180 degrees phase change at the centre of each burst. When such bursts are applied to the resonant circuit by way of a drive amplifier and a second winding wound over the first winding, the required envelope is generated in the first winding.
4706057 MAGNET OF A NUCLEAR SPIN TOMOGRAPH August Schwab, Berlin, Federal Germany assigned to Siemens lschaft
Republic Of Aktiengesel-
A magnet of permanent magnet material for use in a nuclear spin tomograph has a longitudinally extending cavity for receiving a patent, the cavity and the outer contour of the magnet being substantially rectangular. The magnet comprises simple prismatic parts which are assembled unmagnetized. Upon assembly, the magnet is magnetized so that an approximately homogeneous magnetic field prevails in the cavity and the space outside the magnet is approximately free of fields. Magnetically soft plates are disposed on the inside surfaces of two horizontal legs of the magnet.