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1. 发明专利

JP4247511B2 Gradient magnetic field measurement method and apparatus, as well as magnetic resonance imaging apparatus 有权
公开(公告)号：JP4247511B2
公开(公告)日：2009-04-02
申请号：JP2000114619
申请日：2000-04-17
申请人：ジーイー横河メディカルシステム株式会社
发明人：隆男後藤
IPC分类号： A61B5/055 , G01R33/48
摘要： PROBLEM TO BE SOLVED: To provide a method and a device for precisely measuring a gradient magnetic field and a magnetic resonance photographing apparatus with the gradient magnetic field measuring device. SOLUTION: A phantom 400 set in the gradient magnetic field photographs a phantom projection by saturating a spin at a specified position on the gradient axis to detect the position where a signal is lowered, and the difference between the specified position d1 and the detected position d2 is found.

2. 发明专利

JP3384944B2 Mri equipment 失效
公开(公告)号：JP3384944B2
公开(公告)日：2003-03-10
申请号：JP6152897
申请日：1997-03-14
申请人：ジーイー横河メディカルシステム株式会社
发明人：隆男後藤
IPC分类号： G01R33/32 , A61B5/055 , G01R33/565
CPC分类号： G01R33/56518 , G01R33/56563
摘要： For the accurate measurement of the phase shift of echos caused by the inference of the eddy current and residual magnetization attributable to the encode gradient and the like, the measuring process includes the steps of emitting an excitation pulse R, emitting an inversion pulse Pl, applying an encode gradient gyn to the phase axis, applying a read gradient gxr, which is the former half of the usual read gradient, to the read axis, applying a rewind gradient gyrn in which a compensation pulse gypn is put to the phase axis, emitting an inversion pulse P2, applying a dephaser gradient gywdn to the phase axis, sampling data from the echo2 while applying a readout gradient gywn to the phase axis, evaluating the phase shift value of the echo2 caused by the influence of the encode gradient gyn and rewind gradient gyrn based on phase data resulting from the first-order Fourier transform for the sampled data, determining the correction value from the resulting phase shift value, revising the compensation pulse gypn with the correction value, and repeatting these operations an intended number of times while altering the encode gradient gyn.

3. 发明专利

JP3647444B2 Mri equipment 有权
公开(公告)号：JP3647444B2
公开(公告)日：2005-05-11
申请号：JP2003400637
申请日：2003-10-27
申请人：ジーイー横河メディカルシステム株式会社
发明人：隆男後藤
IPC分类号： G01R33/387 , A61B5/055
摘要： PROBLEM TO BE SOLVED: To prevent the degradation of image quality due to eddy currents and residual magnetization caused by a phase encode gradient. SOLUTION: In an MRI system, an excitation RF (radio frequency) pulse is transmitted, then a reversal RF pulse is transmitted, a phase encode gradient is then applied on a warp axis, and finally an NMR signal is received while applying a read gradient on a read axis. After the processes from transmitting the reverse RF pulse to receiving an NMR signal are repeated M times, a killer gradient is applied. The processes from transmitting the excitation RF pulse to applying the killer gradient are repeated N times. Then NMR signals processed by different phase encodes of (M×N) times are collected. The polarity of the killer gradient is switched so as to be identical with the polarity of the sum of phase encode gradients of M times to be applied when processes from transmitting the reverse RF pulse to receiving the NMR signal are repeated M times. COPYRIGHT: (C)2004,JPO

4. 发明专利

JP3505294B2 Mri equipment 失效
公开(公告)号：JP3505294B2
公开(公告)日：2004-03-08
申请号：JP24285795
申请日：1995-09-21
申请人：ジーイー横河メディカルシステム株式会社
发明人：隆男後藤
IPC分类号： G01R33/48 , A61B5/055 , G01R33/565
CPC分类号： G01R33/56527 , G01R33/56518 , G01R33/56563
摘要： The present invention relates to an MRI apparatus capable of preventing the quality of an image from being degraded under the influence of eddy currents and residual magnetization caused by a phase encode gradient. While an RF pulse P1 is sent, a phase encode gradient gy(i) is applied to a warp axis and a read gradient rr is applied to a read axis, an NMR signal is received, followed by application of a rewind gradient gyr(i)' to the warp axis. The rewind gradient gyr(i)' is defined as "(a basic component of opposite polarity equal in time integral value to the phase encode gradient gy(i)) + (a warp-axis correction component for correcting the influence of eddy currents or residual magnetization caused by the phase encode gradient gy(i))".

5. 发明专利

JP3382868B2 Phase shift measuring method and mr imaging equipment 有权
公开(公告)号：JP3382868B2
公开(公告)日：2003-03-04
申请号：JP36398898
申请日：1998-12-22
申请人：ジーイー横河メディカルシステム株式会社
发明人：隆男後藤
IPC分类号： A61B5/055 , G01R33/48
摘要： PROBLEM TO BE SOLVED: To prevent the influence of fluctuation of residual magnetization resulting from changes in gradient magnetic field pulses. SOLUTION: In an FSE sequence, reset pulses gyslj and gysrj which have amplitude equal to maximum amplitude used on a phase axis are inserted on the phase axis in front of and behind an inverted pulse Pj. Therefore, residual magnetization prior to application of phase encoding pulses is always constant irrespective of the history of application of other gradient magnetic field pulses. Thus, the influence of fluctuation of residual magnetization resulting from changes in gradient magnetic field pulses can be prevented.

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