Susceptibility Artifact Removal Method Based on Gradient Compensation for Adaptive Varying Slice Selection Direction

A technology for compensating gradients and magnetic sensitivity, which is applied in magnetic resonance measurement, magnetic variable measurement, and nuclear magnetic resonance imaging system for measurement, etc. It can solve problems such as signal attenuation, magnetic field inhomogeneity, and influence on quantitative measurement, so as to improve efficiency, Remove the effect of handling convenience

Inactive Publication Date: 2019-05-17
PEKING UNIV
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Problems solved by technology

However, in addition to deoxyhemoglobin, there are other reasons for signal attenuation in human tissue, such as the vicinity of the interface between air tissues, or the uneven distribution of the main magnetic field itself, forming susceptibility artifacts, resulting in uneven magnetic fields, which will cause Affects the quantitative measurement of oxygen metabolism indicators such as oxygen uptake fraction OEF

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  • Susceptibility Artifact Removal Method Based on Gradient Compensation for Adaptive Varying Slice Selection Direction
  • Susceptibility Artifact Removal Method Based on Gradient Compensation for Adaptive Varying Slice Selection Direction
  • Susceptibility Artifact Removal Method Based on Gradient Compensation for Adaptive Varying Slice Selection Direction

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[0021] The present invention will be described in further detail below in conjunction with accompanying drawing, the present invention comprises three main modules altogether, as figure 1 As shown, the details are as follows:

[0022] 1. Data acquisition module: During the actual scanning process, at the moment of the maximum ΔTE of the MASE sequence, adaptively obtain the Z-Shimming gradient G zmax , while keeping ΔTE constant, by distributing the maximum Z-Shimming gradient moment equally in the positive and negative directions, according to [0, -1 / 4, -2 / 4, -3 / 4, -4 / 4, 1 / 4, 2 / 4, 3 / 4]×G zmax The rule is applied, and then the compensation gradient after the average distribution is applied, so as to obtain a plurality of magnetic resonance signals compensated by the Z-Shimming gradient.

[0023] 2. ΔB signal attenuation model processing module: the MR signal attenuation caused by the joint action of any compensation gradient in the layer selection direction and the original ...

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Abstract

The invention discloses a new magnetic susceptibility artifact removing method for exerting self-adaptive change shimming gradient (Z-shimming Gradient) in a selection layer direction on the basis of a multi-echo asymmetrical spin-echo fast imaging technology (MASE). The method involves a data collecting module, a delta B signal attenuation model processing module and a magnetic susceptibility artifact removing module. An optimized Z-Shimming gradient method and a sinc model of MR signal attenuation caused by magnetic susceptibility artifacts are well combined through a system, the Z-Shimming gradient is exerted in a self-adaptive mode according to different delta TE times, finally efficiency is improved through a model fitting method, and data for establishing delta B are obtained within 24 seconds; data of delta B and data for estimating oxygen metabolism indexes such as oxygen extraction fraction (OEF) can be obtained through once scanning according to a Z-MASE sequence in the new method, no geometric distribution difference exists between the two types of data, and the magnetic susceptibility artifact removing treatment is more convenient, accurate and robust.

Description

technical field [0001] The invention belongs to the technical field of magnetic resonance medical imaging, in particular to a magnetic sensitivity artifact removal method based on self-adaptive change layer selection direction compensation gradient (Z-shimming Gradient). Background technique [0002] The difference in magnetic susceptibility of biological tissue is closely related to its own function, physiological or pathological state, and this mechanism forms useful contrast information in MRI images. From the BOLD contrast mechanism, it can be known that deoxyhemoglobin, as an endogenous contrast agent, causes signal attenuation on T2*-weighted images (Ogawa et al, Biophysical Journal 1993; Thulborne al, Biochim Biophys Acta 1982). However, in addition to deoxyhemoglobin, there are other reasons for signal attenuation in human tissue, such as the vicinity of the interface between air tissues, or the uneven distribution of the main magnetic field itself, forming susceptib...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R33/56
Inventor 张晓东张珏王霄英安红宇方竞
Owner PEKING UNIV
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