Magnetic resonance imaging method

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 projection curve along the readout direction of the slice includes:

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.

15. The system of claim 14 , 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.