A regularization-based non-uniformity correction method for mri images

A non-uniformity correction and non-uniform technology, applied in image enhancement, image data processing, instruments, etc., can solve the problems of estimating non-uniform field errors, poor universality, and difficulty in determining the frequency threshold of low-pass filtering, etc., to achieve accurate non-uniform Uniform field estimation, increasing the fitting order, and reducing the effect of boundary effects

Active Publication Date: 2016-03-30
UNIV OF SCI & TECH OF CHINA
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Problems solved by technology

[0007] Disadvantages of the algorithm: the second scan requires additional hardware equipment, which increases the scan time; and the displacement of the patient during the two scans causes image mismatch, which requires image registration, making errors in estimating the non-uniform field and causing artifacts
[0011] Disadvantages of the algorithm: there is aliasing between the non-uniform field and the low-frequency information of the image, and the frequency threshold of the low-pass filter is difficult to determine
[0015] Disadvantages of the algorithm: poor universality, only suitable for images of special parts

Method used

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  • A regularization-based non-uniformity correction method for mri images
  • A regularization-based non-uniformity correction method for mri images
  • A regularization-based non-uniformity correction method for mri images

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[0052] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0053] The present invention improves the low-pass filtering method, selects a part of the area with little difference in gray value for low-pass filtering to obtain the initial estimate of the non-uniform field, and then extrapolates through a regularized polynomial fitting method, Obtain an inhomogeneous field estimate of the full image. The specific process is as follows:

[0054] 1. Determination of the area of ​​interest

[0055] The method of directly filtering the image is likely to cause boundary effects, that is, the non-uniformity distortion in the high-contrast area, which will easily cause large errors in the subsequent interpolation, but in fact most of the data in the interpolation fitting. is redundant and unnecessary. Therefore, in the present invention, we avoid boundary effects by selecting some areas with close gray values...

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Abstract

The invention provides an MRI image inhomogeneity correction method based on regularization. A lowpass filtering method is improved, part of an area with low grey-value difference is selected and is subjected to lowpass filtering to obtain an initial estimate for a inhomogeneous field, and then extrapolation is performed through a regularized polynomial fitting method to obtain an estimate for an inhomogeneous field of a whole image. According to the method provided by the invention, an area-of-interest is determined and is subjected to filtering, so the boundary effect in the global image filtering method can be avoided, and fitting is performed through a regularization method, thus overfitting is guaranteed not to happen under the condition of improving the fitting order.

Description

technical field [0001] The invention relates to the technical field of nuclear magnetic resonance and image processing, in particular to a method for correcting non-uniformity of MRI images based on regularization. Background technique [0002] In recent ten years, MRI has been widely used in medical diagnosis due to its advantages of high resolution, no ionizing radiation damage and imaging at any angle. With the demand for higher resolution scanned images, the magnetic field strength of the scanner is getting higher and higher, and the magnetic field gradient is finer and finer. But the ensuing problem is that the interference of the non-uniform field suffered by the MRI image is becoming more and more serious. The inhomogeneous field is the deviation field caused by the inhomogeneity of the transmitted spatial magnetic field or the inhomogeneity of the receiving coil sensitivity. This deviation field is generally assumed to be a smooth, slowly changing multiplicative dev...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T5/00
Inventor 凌强李朝辉宋凯凯李峰
Owner UNIV OF SCI & TECH OF CHINA
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