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Magnetic resonance imager

A technology of a transmitting device and a signal receiving device, which is applied in the directions of magnetic resonance measurement, measurement using nuclear magnetic resonance imaging system, measurement device, etc. distribution, etc.

Inactive Publication Date: 2003-09-03
GE MEDICAL SYST GLOBAL TECH CO LLC
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Problems solved by technology

[0014] As mentioned above, there is a problem with the conventional static magnetic field inhomogeneity distribution measurement sequence SQJ that it cannot accurately measure the static magnetic field inhomogeneity distribution because the magnetization varies due to gradient pulses
[0015] Therefore, correct image correction cannot be performed, and the image quality will be significantly reduced, especially when an imaging method that utilizes the resonance frequency difference between water and fat is used in an MRI device with a medium-low intensity magnetic field (0.3-0.5T), such as CHESS (Chemical Substitution Selective Imaging) method, especially
[0016] In order to solve this problem, the inventors of the present invention studied the effect of using the device disclosed in Japanese Patent Application No. 2001-54510, but the distribution of the static magnetic field inhomogeneity cannot be measured very accurately only by using this device

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  • Magnetic resonance imager
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Embodiment approach

[0085] Figure 5 is a pulse sequence diagram of the static magnetic field inhomogeneity distribution measurement sequence SQ2 in the second embodiment.

[0086] This static magnetic field inhomogeneity distribution measurement sequence SQ2 applies a radio frequency pulse P1 and a slice-selective gradient pulse Ss1; followed by a slice-rephasing gradient pulse Sr1 whose intensity is equal to half the intensity of the slice-selective gradient pulse Ss1 or Approximately half; apply a slice encoding gradient pulse Se1; apply a slice encoding gradient pulse Se1; apply a phase encoding gradient pulse Pe1; apply a frequency dephasing gradient pulse Fd1 whose intensity is equal to twice the intensity of the readout gradient pulse Ro1 or Roughly two times; subsequently acquire the first MR data while applying the readout gradient pulse Ro1; then apply a slice inversion gradient pulse Sr1 whose intensity is equal to or approximately half that of the slice encoding gradient pulse Se1; ap...

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Abstract

For the purpose of thoroughly reducing the effect of residual magnetization caused by gradient pulses, the strength of a phase rewinding gradient is made half or about half of that of a phase encoding gradient; the strength of a slice rewinding gradient is made half or about half of that of a slice encoding gradient; a killer gradient having an intensity equal to that of the slice selective gradient is applied to the slice axis; and a killer gradient having an intensity equal to that of a readout gradient is applied to the frequency axis subsequent to the readout gradient.

Description

technical field [0001] The present invention relates to a static magnetic field inhomogeneity distribution measurement method, a static magnetic field homogenization method, an MR (magnetic resonance) data acquisition method and an MRI (magnetic resonance imaging) device, in particular to a static magnetic field inhomogeneity measurement method , a static magnetic field homogenization method, an MR data acquisition method, and an MRI device, which can completely reduce the residual magnetization effect generated by gradient pulses. technical background [0002] exist Figure 7 A known measurement sequence SQJ of static magnetic field inhomogeneity distribution is described in . [0003] This static magnetic field inhomogeneity distribution measurement sequence SQJ applies a radio frequency pulse P1 and a slice selective gradient pulse Ss1; then applies a slice rephasing gradient pulse Sr1', whose intensity (amplitude) is equal to the slice selective gradient pulse Ss1 inten...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R33/48A61B5/055G01R33/387G01R33/565
CPCG01R33/56518G01R33/387G01R33/56563
Inventor 浅野健二小杉进
Owner GE MEDICAL SYST GLOBAL TECH CO LLC