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3D-DESS sequence optimization method, 3D-DESS optimization sequence and magnetic resonance imaging shimming method

A magnetic resonance imaging and optimization method technology, applied in the direction of measuring magnetic variables, measuring devices, instruments, etc., can solve the problems of poor shimming effect, readout gradient eddy current cannot be eliminated, etc., to reduce influence, reduce phase shift, Eliminates the effect of gradient field phase shift

Active Publication Date: 2021-07-09
MARVEL STONE HEALTHCARE CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a 3D-DESS sequence optimization method, a 3D-DESS optimization sequence and a shimming method for reducing the influence of eddy currents in a magnetic resonance imaging system, which are used to solve the problem of reading 3D-DESS sequences in the prior art. The eddy current in the gradient cannot be eliminated, so the technical problem of poor shimming effect

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  • 3D-DESS sequence optimization method, 3D-DESS optimization sequence and magnetic resonance imaging shimming method
  • 3D-DESS sequence optimization method, 3D-DESS optimization sequence and magnetic resonance imaging shimming method
  • 3D-DESS sequence optimization method, 3D-DESS optimization sequence and magnetic resonance imaging shimming method

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Embodiment 1

[0049] Such as Figure 1-2 As shown, the eddy current in the readout gradient direction of the shimming sequence of the 3D-DESS (three-dimensional double-echo steady state sequence) in the prior art decreases with time during signal acquisition, and the eddy current of the readout gradient during two signal acquisitions The eddy current is different, and there is no simple linear relationship, so it cannot be eliminated, resulting in poor shimming effect and affecting the imaging quality of magnetic resonance images. For this reason, this embodiment proposes a 3D-DESS sequence optimization method to optimize the existing 3D-DESS sequence to eliminate the influence of eddy currents on shimming.

[0050] Such as image 3 As shown, this embodiment provides a method for optimizing a 3D-DESS sequence, the 3D-DESS sequence includes two echo signal acquisitions, and the method includes:

[0051] Step a: Divide the readout gradient GR of the two echo signal acquisitions, and establi...

Embodiment 2

[0062] See Figure 4-5 On the basis of the first embodiment, this embodiment also provides a 3D-DESS optimized sequence, the preferred 3D-DESS sequence is obtained by the method for optimizing the 3D-DESS sequence as described in the first embodiment.

[0063] Among them, it should be noted that, in Figure 4 Among them, RF represents the time axis of radio frequency pulse, GS represents the time axis of layer selection gradient, GP represents the time axis of phase encoding gradient, ED represents the time axis of eddy current, GR represents the time axis of readout gradient, and RX represents the time axis of collecting and receiving signals.

[0064] Specifically, with Figure 1-2 compared to, Figure 4-5 On the readout gradient GR axis, the readout gradient of the two signal acquisitions is divided, and a reverse compensation gradient with an intensity h is established between the two sampling intervals, by adjusting the intensity h of the reverse compensation gradient ...

Embodiment 3

[0067] Please refer to Figure 5-8 On the basis of Embodiment 2, this embodiment also provides a shimming method for reducing the influence of eddy currents in a magnetic resonance imaging system. The 3D-DESS optimization sequence described in Embodiment 2 is applied in this embodiment, so The shimming methods described include:

[0068] Step 1: Using the 3D-DESS optimization sequence to scan and collect image data of the imaging region;

[0069] Step 2: performing signal separation on the two collected echo signals, and respectively obtaining the corresponding first phase data and second phase data in the readout gradient GR;

[0070] Wherein, it should be noted that the two echo signals include the FID echo signal excited by the first RF pulse and the echo signal refocused by the second RF pulse; in addition, in order to ensure that the second RF pulse The converged echo signal is a spin echo signal, more preferably, the echo time TE of the FID echo signal 1 and the echo ...

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Abstract

The invention relates to the technical field of magnetic resonance imaging, and discloses a 3D-DESS sequence optimization method, a 3D-DESS optimization sequence and a shimming method for reducing eddy current influence in a magnetic resonance imaging system, and the optimization method comprises the steps: carrying out the segmentation of a readout gradient GR collected by two times of echo signals, and building a reverse compensation gradient with the intensity of h between the two times of sampling intervals; adjusting the intensity h of the reverse compensation gradient to obtain an optimal intensity value so as to obtain an optimal eddy intensity value corresponding to the eddy intensity eh generated by the reverse compensation gradient, wherein the eddy current of the second echo signal acquisition readout gradient GR corresponding to the optimal eddy current intensity value is the same as the eddy current of the first echo signal acquisition readout gradient GR in size. The 3D-DESS optimized sequence obtained through the optimization method of the 3D-DESS sequence can eliminate eddy current generated in the readout gradient of the sequence in a subsequent magnetic resonance imaging shimming method, so that gradient field phase deviation caused by the eddy current is reduced, and the imaging quality of an image is improved.

Description

technical field [0001] The invention belongs to the technical field of nuclear magnetic resonance imaging, and in particular relates to a 3D-DESS sequence optimization method, a 3D-DESS optimization sequence and a magnetic resonance imaging shimming method. Background technique [0002] Magnetic Resonance Imaging (MRI) is one of the most advanced tools in modern medical imaging diagnosis. The realization of MRI is the result of the joint action of the main magnetic field, gradient field and radio frequency. The gradient magnetic field can realize the spatial positioning of the magnetic resonance signal in the main magnetic field, making magnetic resonance imaging possible. The gradient magnetic field is generated by applying current to the gradient coil. When the rapidly switched current passes through the gradient coil, it will cause an eddy current (Eddy Current) effect on the surrounding metal parts, which will shift the phase of the gradient field and cause magnetic reso...

Claims

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Application Information

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IPC IPC(8): G01R33/561G01R33/565
CPCG01R33/561G01R33/56518
Inventor 赵越罗海王伟谦解运浩胡剑雄吴子岳
Owner MARVEL STONE HEALTHCARE CO LTD
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