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    • 7. 发明授权
    • Nuclear magnetic resonance imaging apparatus
    • 核磁共振成像装置
    • US4889127A
    • 1989-12-26
    • US37855
    • 1987-04-13
    • Ryuzaburo TakedaHideaki KoizumiYoshiyuki Miyamoto
    • Ryuzaburo TakedaHideaki KoizumiYoshiyuki Miyamoto
    • A61B10/00A61B5/055G01R33/48G01R33/563
    • G01R33/563
    • A nuclear magnetic resonance imaging apparatus for deriving a signal from a moving part of an object to be imaged, includes a gradient magnetic field generator for applying a gradient magnetic field to the object; and a radio frequency magnetic field generator for applying a radio frequency magnetic field to the object to present a nuclear magnetic resonance phenomenon. Pulses of a 180 degree pulse method are generated to remove an adverse effect of ununiformity of a static magnetic field; two gradient magnetic fields having the same amplitude and grading oppositely to each other are applied at a certain time interval therebetween to the moving part of the object in the direction of motion of the moving object; a radio frequency magnetic field is generated by applying a pulse in the pulses of the 180 degree pulse method succeeding a 180 degree pulse at the time corresponding to the center of an echo signal generated by the 180 degree pulse, the radio frequency magnetic field making a nuclear spin vector at the stationary part of the object in parallel to the static magnetic field; a resonance signal is detected which is produced from the object upon application of the radio frequency magnetic field; the above process is performed to further obtain another resonance signal, reversing the polarities of the gradient magnetic fields; and a difference between the two resonance signals is derived as a signal from the moving part of the object.
    • 用于从待成像对象的移动部分导出信号的核磁共振成像装置包括用于向对象施加梯度磁场的梯度磁场发生器; 以及用于对物体施加射频磁场以呈现核磁共振现象的射频磁场发生器。 产生180度脉冲方式的脉冲以消除静磁场不均匀性的不利影响; 以相对于彼此相反的幅度和等级的两个梯度磁场在其间的特定时间间隔被施加到物体的运动部分在运动物体的运动方向上; 通过在对应于由180度脉冲产生的回波信号的中心的时间的180度脉冲之后的180度脉冲方式的脉冲中施加脉冲,产生射频磁场来产生射频磁场, 核自旋矢量在物体的静止部分平行于静磁场; 检测在应用射频磁场时从物体产生的共振信号; 执行上述处理以进一步获得另一谐振信号,反转梯度磁场的极性; 并且导出两个谐振信号之间的差异作为来自物体的运动部分的信号。
    • 10. 发明授权
    • Magnetic resonance imaging method
    • 磁共振成像方法
    • US4724388A
    • 1988-02-09
    • US869976
    • 1986-06-02
    • Koichi SanoTetsuo YokoyamaHideaki Koizumi
    • Koichi SanoTetsuo YokoyamaHideaki Koizumi
    • G01R33/565G01R33/20
    • G01R33/56518G01R33/56563
    • In order to measure a static field distribution with one scanning operation and to make image distortion corrections with the static field distribution and a gradient field distribution simultaneously considered, an image is reconstructed using a spin echo signal produced under the condition that a time interval between a 90.degree. pulse and a 180.degree. pulse differs from an interval between the 180.degree. pulse and the time origin of the spin echo signal, the static field distribution is evaluated from the relation of distortions to phase errors free from a phase distortion attributed to the characteristic of a detecting part and a phase distortion attributed to the dynamic characteristic of the gradient field, a relations existing between the spatial distortion and phase distortion of the reconstructed image and a magnetic field distribution including the gradient field is obtained, and the distortion magnitude of the reconstructed image is evaluated from the measured magnetic field distribution.
    • 为了通过一次扫描操作测量静态场分布,并且同时考虑静态场分布和梯度场分布进行图像失真校正,使用自旋回波信号来重构图像,该自旋回波信号是在 90°脉冲和180°脉冲与180°脉冲与自旋回波信号的时间原点之间的间隔不同,静态场分布从失真和相位误差的关系来评估,该相位误差不包括归因于特性的相位失真 得到归因于梯度场的动态特性的检测部分和相位失真,获得重建图像的空间失真和相位失真之间存在的关系以及包括梯度场的磁场分布,并且, 从测量的磁场分布评估重建图像 。