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    • 4. 发明授权
    • Apparatus and method for stabilizing the background magnetic field
during MRI
    • MRI检测背景磁场的装置及方法
    • US5245286A
    • 1993-09-14
    • US702428
    • 1991-05-20
    • Joseph W. CarlsonDavid M. Goldhaber
    • Joseph W. CarlsonDavid M. Goldhaber
    • A61B5/055G01R33/387G01R33/3875G01R33/389G01R33/56G01R33/565
    • G01R33/389G01R33/56563
    • A pair of serially-connected coils detect noise variations in an MRI background magnetic field. Although the coils are closely coupled to the primary background magnetic field generator of the MRI system, they are disposed so as to be substantially de-coupled from rapidly changing MRI gradient magnetic fields. The noise detecting loops drive a negative feedback loop including a low pass filter, amplifier and controlled current source driving a large correcting loop. The device attenuates background magnetic field noise during MRI data acquisition over a frequency band extending from a few millihertz to more than 100 Hz. It is preferably used with existing field stabilization software that otherwise compensates for fluctuations in an overlapping frequency band which starts at d.c. Thus, when used together, background magnetic field noise may be attenuated (or compensated for in subsequent MRI data processing) over a frequency band that extends from d.c. to more than 100 Hz.
    • 一对串联线圈检测MRI背景磁场中的噪声变化。 虽然线圈紧密耦合到MRI系统的主要背景磁场发生器,但是它们被布置成与快速变化的MRI梯度磁场基本上脱耦合。 噪声检测环路驱动负反馈回路,包括低通滤波器,放大器和驱动大校正环路的受控电流源。 该装置在从几毫赫到多于100赫兹的频带上的MRI数据采集期间衰减背景磁场噪声。 它优选与现有的场稳定软件一起使用,否则补偿以直流开始的重叠频带中的波动。 因此,当一起使用时,背景磁场噪声可以在从直流延伸的频带上衰减(或在随后的MRI数据处理中补偿)。 超过100 Hz。