Method for correcting gray distortion of nuclear magnetic resonance image

A technology of nuclear magnetic resonance image and gray scale distortion, applied in the direction of measuring magnetic variables, measuring devices, instruments, etc., can solve the problems of impossible real-time image reconstruction, etc., and achieve the effect of improving reliability and imaging quality

Active Publication Date: 2014-03-12
JIANGSU MAGSPIN INSTR
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Problems solved by technology

However, the calculation time of reconstruction will increase by N/log2N times...

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  • Method for correcting gray distortion of nuclear magnetic resonance image
  • Method for correcting gray distortion of nuclear magnetic resonance image
  • Method for correcting gray distortion of nuclear magnetic resonance image

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Embodiment Construction

[0015] In order to make the purpose, technical solution and advantages of the present invention clearer, the method for correcting the gray scale distortion of the nuclear magnetic resonance image of the present invention will be described in detail below.

[0016] In MRI theory, the image space ( ) and k-space ( ) are related by Fourier transform. After the scanning object is excited by the rf pulse, the three-dimensional gradient space encoding is added to generate an oscillating signal. The three-dimensional Fourier transform can be written as:

[0017]

[0018]

[0019] in, is the signal in k-space, is the scan object spin density in image space, is the image grayscale in the final image space. The three time function components of k can be obtained by integrating their respective gradient components:

[0020]

[0021] in, is a constant, is the gradient component.

[0022] In standard MRI procedures, time-domain signals are acquired at a uniform v...

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Abstract

The invention discloses a method for correcting gray distortion of a nuclear magnetic resonance image. The method comprises the following steps that: spherical-harmonic expansion is performed on a nonlinear gradient field so as to obtain a linear term and a higher-order nonlinear term; the heterogeneity of the gradient field can be obtained through conventional fast Fourier transform (FFT); a heterogeneous mapping relationship between the geometric position and brightness of the image is obtained; a weighted coefficient between the nonlinearity of the gradient field and the gray distortion of the image; and therefore, the correction of the gray distortion of the image can be accomplished. Compared with the prior art, the method for correcting the gray distortion of the nuclear magnetic resonance image of the invention can quickly realize the correction of the gray distortion of the nuclear magnetic resonance image, and therefore, imaging quality and the reliability of clinical diagnosis can be improved, and the method has important significance in the nuclear magnetic resonance imaging field.

Description

technical field [0001] The invention relates to nuclear magnetic resonance imaging, in particular to a method for correcting the gray scale distortion of the nuclear magnetic resonance image. Background technique [0002] In MRI systems, image quality depends on the accuracy of the spatial encoding of the imaged object. Stereotaxic brain surgery, brain atrophy and longitudinal measurement of functional brain imaging, among others, use image deformation and correspondingly magnetic field homogeneity as decisive factors. The magnetic field non-uniformity that can cause image gray level non-uniformity includes electromagnetic eddy current, gradient non-uniformity, and B0 and B1 non-uniformity. [0003] The development trend of gradients in recent years is characterized by short-cavity designs and high-speed flipping, but these designs encounter the problem of thermal stimulation of nerve endings caused by large flipping currents. Especially in some applications such as EPI (e...

Claims

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Application Information

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IPC IPC(8): G01R33/565
Inventor 赵华炜
Owner JIANGSU MAGSPIN INSTR
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