Abstract: To achieve a good balance among the magnetic field intensity, region of homogeneous magnetic field intensity and cost, a magnetic field generating apparatus for generating a magnetic field in a vertical direction comprises: a pair of magnets having respective magnetic poles with mutually opposite polarities disposed to face each other in a vertical direction, for generating a static magnetic field having different dimensions of its region of homogeneous magnetic field intensity in two mutually orthogonal directions in a horizontal plane; a pair of planar magnetic elements, each element supporting respective one of the pair of the magnets; and a vertical columnar magnetic element lying in a direction different from the two directions, each end of which is joined to respective one of the pair of the planar magnetic elements.

Abstract: To achieve a good balance among the magnetic field intensity, region of homogeneous magnetic field intensity and cost, a magnetic field generating apparatus for generating a magnetic field in a vertical direction comprises: a pair of magnets having respective magnetic poles with mutually opposite polarities disposed to face each other in a vertical direction, for generating a static magnetic field having different dimensions of its region of homogeneous magnetic field intensity in two mutually orthogonal directions in a horizontal plane; a pair of planar magnetic elements, each element supporting respective one of the pair of the magnets; and a vertical columnar magnetic element lying in a direction different from the two directions, each end of which is joined to respective one of the pair of the planar magnetic elements.

Abstract: The present invention is intended to provide a magnet apparatus obviating the necessity of shield coils designed to suppress eddy currents. The magnet apparatus has gradient coils disposed in a bore of a cylindrical superconducting magnet, and includes a cylindrical structure that is realized with a combination of tiles made of a high-permeability material and that is interposed between the internal surface of the superconducting magnet and the external surface of the gradient coils. The tiles made of a high-permeability material are laminates made of a high-permeability material. The high-permeability material is a silicon steel plate or an amorphous magnetic material.

Abstract: The present invention is intended to provide a magnet apparatus obviating the necessity of shield coils designed to suppress eddy currents. The magnet apparatus has gradient coils disposed in a bore of a cylindrical superconducting magnet, and includes a cylindrical structure that is realized with a combination of tiles made of a high-permeability material and that is interposed between the internal surface of the superconducting magnet and the external surface of the gradient coils. The tiles made of a high-permeability material are laminates made of a high-permeability material. The high-permeability material is a silicon steel plate or an amorphous magnetic material.

Abstract: To correct static magnetic field intensity and homogeneity of an MRI system, B0 correction coil driving power sources respectively supply correction electric currents to B0 correction coils added to a pair of pillar yokes at the position where an imaging region is interposed therebetween, and the pair of B0 correction coils produce correction magnetic fields in which at least one of the direction and intensity is different, which are then applied to static magnetic fields produced by permanent magnets.

Abstract: In order to reduce residual magnetization caused by gradient pulses, for a gradient pulse having either a positive or negative polarity, a residual magnetization reducing pulse is applied after applying the gradient pulse, or for two or more successively applied gradient pulses having different polarities, the amplitude of the gradient pulse(s) is adjusted to reduce residual magnetization thereafter.

Abstract: The present invention aims to reduce degradation in image quality due to residual magnetization. In a pulse sequence of a high-speed spin echo process, a pre-pulse is applied before an excitation pulse, and a correction pulse for correcting a phase error caused by the pre-pulse is applied before an initial inversion pulse.

Abstract: To correct static magnetic field intensity and homogeneity of an MRI system, B0 correction coil driving power sources respectively supply correction electric currents to B0 correction coils added to a pair of pillar yokes at the position where an imaging region is interposed therebetween, and the pair of B0 correction coils produce correction magnetic fields in which at least one of the direction and intensity is different, which are then applied to static magnetic fields produced by permanent magnets.

Abstract: In order to accurately measure a gradient magnetic field, a pre-encoding pulse Pk is applied, data S(k, 1)-S(k, T) are collected from an FID signal while applying an encoding pulse Ge having a gradient waveform to be measured, and the above steps are repeated K times with the magnitude of the pre-encoding pulse Pk varied; data D(1,1)-D(1, T−1), D(2, 1)-D(2, T−1), . . . , D(K, 1)-D(K, T−1) having a phase difference &Dgr;&phgr; as an angle are obtained from the collected data S(1,1)-S(1, T), S(2, 1)-S(2, T), . . . , S(K, 1)-S(K, T); data having corresponding magnitudes of the encoding pulse Ge are added to obtain added data d(1)-d(T−1); gradient magnetic field differences &Dgr;G(1)-&Dgr;G(T−1) are obtained from the added data d(1)-d(T−1); and the gradient magnetic field differences &Dgr;G(1)-&Dgr;G(T−1) are integrated to obtain a gradient magnetic field G(1)-G(T−1).

Abstract: In order to provide a selective excitation method and apparatus that is not affected by the non-linearity of a gradient magnetic field, and a magnetic resonance imaging method and apparatus employing such a selective excitation apparatus, a frequency f is employed as an RF excitation frequency, corresponding to a slice position Zc redefined differently from a specified slice position Za according to a non-linearity error in a gradient magnetic field Gz. Alternatively, the gradient is adjusted so that the frequency of spins at a specified slice position Za equals to a frequency f of the RF excitation signal.

Abstract: The present invention aims to reduce degradation in image quality due to residual magnetization. In a pulse sequence of a high-speed spin echo process, a pre-pulse is applied before an excitation pulse, and a correction pulse for correcting a phase error caused by the pre-pulse is applied before an initial inversion pulse.

Abstract: In order to reduce ghosts due to increasing echo intensity fall-off in the course of an echo train in MR imaging employing the FSE method, the present method assigns individual echoes in the echo train to respective segments to acquire data F(S1-S3), then assigns individual echoes arranged in the reverse order to the respective segments so that the order of signal intensity magnitude in the data F is inverted, to acquire data R(S4-S5), adds the data F and R for each view, and produces an image from the sum data. The number of echoes in the echo train is preferably selected to be an even number.

Abstract: In order to enable the application of a forcible recovery pulse to the multi-slice technique, when selective inversion pulses satisfy the CPMG condition or the CP condition and ETL (Echo Train Length) is even, a dummy selective inversion pulse is applied at the end of each pulse sequence of the fast spin echo technique for each slice, then a dummy read axis gradient is applied without acquiring MR data, then a refocusing pulse selective of only the current slice is applied, and subsequently a forcible recovery pulse sequence FR selective of only the current slice is applied.