Magnetic resonance imaging method

Patent metadata

Field	Value
Publication number	US-11099252-B2
Application number	US-201515541167-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Nov 12, 2014
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

The method for magnetic resonance imaging described in the present disclosure may include generating an inversion recovery image by scanning an object using an inversion recovery sequence. The method may also include generating a real part image corresponding to the inversion recovery image by processing the inversion recovery image. The method may also include obtaining a signal line of a reference image without inversion recovery, the reference image corresponding to the real part image. The method may also include determining a phase-corrected signal line of the reference image by performing a phase correction on the signal line of the reference image. The method may also include determining a polarity of the real part image based on the phase-corrected signal line of the reference image.

First claim

We claim:

1. A method for magnetic resonance imaging, the method comprising:
generating an inversion recovery image by scanning an object using an inversion recovery sequence;
generating a real part image corresponding to the inversion recovery image by processing the inversion recovery image;
obtaining, without inversion recovery, a signal line of a reference image, the reference image corresponding to the real part image;
determining a phase-corrected signal line of the reference image by performing a phase correction on the signal line of the reference image; and
determining a polarity of the real part image based on the phase-corrected signal line of the reference image, wherein
the signal line of the reference image corresponds to an inversion recovery image line,
the phase-corrected signal line of the reference image corresponds to a phased-corrected inversion recovery image line,
a corrected phase of the phase correction is determined by:
φ( x,y 0 )=phase( Ŝ ( x,y 0 )*conj( S ( x,y 0 ))), wherein

Ŝ(x, y 0 ) representing a phase-corrected inversion recovery image line,
S(x, y 0 ) representing an inversion recovery image line,
φ(x,y 0 ) representing the corrected phase,
conj representing an operation of determining a conjugate value, and
phase representing an operation of determining a phase, and
the phase-corrected signal line of the reference image is determined by {circumflex over (L)}(x,y 0 )=L(x,y 0 )*exp(1i*φ(x,y 0 )), {circumflex over (L)}(x,y 0 ) representing the phase-corrected signal line of the reference image, and L(x,y 0 ) representing the signal line of the reference image.

2. The method of claim 1 , wherein the signal line of the reference image is obtained before or after the real part image is generated.

3. The method of claim 1 , wherein the polarity of the real part image is determined by determining whether a sum of real parts of the phase-corrected signal line of the reference image is positive or negative.

4. The method of claim 3 , further comprising:
in response to a determination that the sum of the real parts of the phase-corrected signal line of the reference image is positive, determining that the polarity of the real part image is correct; and
in response to a determination that the sum of the real parts of the phase-corrected signal line of the reference image is negative, determining that the polarity of the real part image is incorrect and inversing the polarity of the real part image.

5. The method of claim 1 , wherein the step of generating the real part image corresponding to the inversion recovery image comprises:
generating a phase-corrected inversion recovery image by performing a phase correction on the inversion recovery image; and
generating the real part image corresponding to the inversion recovery image by determining real parts of the phase-corrected inversion recovery image.

6. The method of claim 1 , wherein the step of obtaining the signal line of the reference image comprises:
determining a projection curve along a readout direction of a slice;
determining a y 0 th line in a phase encoding direction of the real part image based on the projection curve, wherein a peak of the projection curve corresponds to the y 0 th line in the phase encoding direction of the real part image; and
determining the signal line of the reference image corresponding to the y 0 th line in the phase encoding direction of the real part image.

7. The method of claim 6 , wherein the step of determining the projection curve along the readout direction of the slice comprises:
acquiring a zero phase encoding line by designating the phase encoding direction of the real part image as a readout direction of the signal line of the reference image; and
performing a one-dimensional Fourier transform on the zero phase encoding line to determine the projection curve along the readout direction of the slice.

8. The method of claim 7 , wherein the projection curve along the readout direction of the slice is a projection curve along a readout direction of a middle slice of the object.

9. A system for magnetic resonance imaging, the system comprising:
a storage device storing instructions, and
at least one processor, when executing the instructions, the at least one processor configured to cause the system to perform operations including:
generating an inversion recovery image by scanning an object using an inversion recovery sequence;
generating a real part image corresponding to the inversion recovery image by processing the inversion recovery image;
obtaining, without inversion recovery, a signal line of a reference image, the reference image corresponding to the real part image;
determining a phase-corrected signal line of the reference image by performing a phase correction on the signal line of the reference image; and
determining a polarity of the real part image based on the phase-corrected signal line of the reference image, wherein
the signal line of the reference image corresponds to an inversion recovery image line,
the phase-corrected signal line of the reference image corresponds to a phased-corrected inversion recovery image line,
a corrected phase of the phase correction is determined by:
φ( x,y 0 )=phase( Ŝ ( x,y 0 )*conj( S ( x,y 0 ))), wherein

Ŝ(x, y 0 ) representing a phase-corrected inversion recovery image line,
S(x, y 0 ) representing an inversion recovery image line,
φ(x,y 0 ) representing the corrected phase,
conj representing an operation of determining a conjugate value, and
phase representing an operation of determining a phase, and
the phase-corrected signal line of the reference image is determined by {circumflex over (L)}(x,y 0 )=L(x,y 0 )*exp(1i*φ(x,y 0 ), {circumflex over (L)}(x,y 0 ) representing the phase-corrected signal line of the reference image, and L(x,y 0 ) representing the signal line of the reference image.

10. The system of claim 9 , wherein the signal line of the reference image is obtained before or after the real part image is generated.

11. The system of claim 9 , wherein the operation of determining the polarity of the real part image based on the phase-corrected signal line of the reference image includes:
determining whether a sum of real parts of the phase-corrected signal line of the reference image is positive or negative.

12. The system of claim 11 , wherein the operation of determining the polarity of the real part image based on the phase-corrected signal line of the reference image further includes:
in response to determining that the sum of the real parts of the phase-corrected signal line of the reference image is positive, determining that the polarity of the real part image is correct; and
in response to determining that the sum of the real parts of the phase-corrected signal line of the reference image is negative, determining that the polarity of the real part image is incorrect and reversing the polarity of the real part image.

13. The system of claim 9 , wherein the operation of obtaining the signal line of the reference image comprises:
determining a projection curve along a readout direction of a slice;
determining a y 0 th line in a phase encoding direction of the real part image based on the projection curve, wherein a peak of the projection curve corresponds to the y 0 th line in the phase encoding direction of the real part image; and
determining the signal line of the reference image corresponding to the y 0 th line in the phase encoding direction of the real part image.

14. The system of claim 13 , wherein the operation of determining the pro

Assignees

• Shanghai United Imaging Healthcare Co Ltd

Inventors

• Shen Baozhong
• Zhang Weiguo

Classifications

• G01R33/565

  Correction of image distortions, e.g. due to magnetic field inhomogeneities · CPC title

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• G01R33/5602 Primary

  by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse · CPC title

• A61B2576/023

  for the heart · CPC title

• A61B5/7257

  using Fourier transforms · CPC title