METHODS AND SYSTEMS FOR SAMPLING K-SPACE DATA IN MAGNETIC RESONANCE IMAGING

• US 20200132793A1
• Filed: 10/24/2018
• Published: 04/30/2020
• Est. Priority Date: 10/24/2018
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Nie, Lisha, Lai, Yongchuan, Liu, Xuan
• Granted Patent: US 10,768,252 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 33/482 using a Cartesian trajectory
• CPC Class Codes: G01R 33/4824 using a non-Cartesian trajectory
• CPC Class Codes: G01R 33/543 Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription G01R33/546 takes precedence
• CPC Class Codes: G01R 33/561 by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
• CPC Class Codes: G01R 33/5611 Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE structural details of arrays of sub-coils G01R33/3415
• CPC Class Codes: G01R 33/5615 Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]

Abstract

Various methods and systems are provided for acquiring k-space data for magnetic resonance imaging. In one example, after applying a phase encoding gradient, the k-space data of a phase angle is acquired while applying a frequency encoding gradient. An amplitude of the phase encoding gradient and a duration of the phase encoding gradient determined based on each and every of a phase angle of the phase encoding line and a duration of the frequency encoding gradient.

Claims

1. A method for magnetic resonance imaging (MRI), comprising:

applying a phase encoding gradient corresponding to a phase encoding line in a circular Cartesian k-space, wherein an amplitude and a duration of the phase encoding gradient vary with a position of the phase encoding line in the circular Cartesian k-space; and

acquiring k-space data along the phase encoding line in the circular Cartesian k-space by applying a frequency encoding gradient, wherein a duration of the acquiring k-space data varies with the position of the phase encoding line in the k-space.

2. The method of claim 1, wherein the closer the phase encoding line is to the center of the k-space, the longer the duration of the acquiring k-space data, and the further the phase encoding line is from the center of the k-space, the shorter the duration of the acquiring k-space data.

3. The method of claim 1, wherein the closer the phase encoding line is to the center of the k-space, the shorter the duration of the phase encoding gradient, and the further the phase encoding line is from the center of the k-space, the longer the duration of the phase encoding gradient.

4. The method of claim 1, wherein the phase encoding line with the maximum amplitude of the phase encoding gradient is between the phase encoding line the closest to the center of the k-space and the phase encoding line the furthest from the center of the k-space.

5. The method of claim 1, wherein the duration of the frequency encoding gradient does not change with the phase encoding line, and the duration of acquiring the k-space data is a portion of the duration of the frequency encoding gradient.

6. The method of claim 5, wherein the duration of the frequency encoding gradient overlaps with the duration of the phase encoding gradient.

7. The method of claim 1, wherein the duration of the frequency encoding gradient varies with the position of the phase encoding line in the k-space.

14. The MRI apparatus of claim 1, wherein the duration of the frequency encoding gradient varies with the position of the phase encoding line in the k-space.

8. A magnetic resonance imaging (MRI) apparatus, comprising:

a frequency gradient coil;

a phase gradient coil;

a controller unit coupled to the frequency gradient coil and the phase gradient coil; and

a memory storing executable instructions that, when executed, cause the controller unit to;

apply a phase encoding gradient corresponding to a phase encoding line in a circular Cartesian k-space via the phase gradient coil, wherein an amplitude and a duration of the phase encoding gradient vary with a position of the phase encoding line in the circular Cartesian k-space; and

acquire k-space data along the phase encoding line in the circular Cartesian k-space by applying a frequency encoding gradient via the frequency gradient coil, wherein a duration of the acquiring k-space data varies with the position of the phase encoding line in the k-space.

9. The MRI apparatus of claim 8, wherein the closer the phase encoding line is to the center of the k-space, the longer the duration of the acquiring k-space data, and the further the phase encoding line is from the center of the k-space, the shorter the duration of the acquiring k-space data.

10. The MRI apparatus of claim 8, wherein closer the phase encoding line is to the center of the k-space, the shorter the duration of the phase encoding gradient, and the further the phase encoding line is from the center of the k-space, the longer the duration of the phase encoding gradient.

11. The MRI apparatus of claim 8, wherein the phase encoding line with the maximum amplitude of the phase encoding gradient is between the phase encoding line the closest to the center of the k-space and the phase encoding line the furthest to the center of the k-space.

12. The MRI apparatus of claim 8, wherein the duration of the frequency encoding gradient does not change with the phase encoding line, and the duration of acquiring the k-space data is a portion of the duration of the frequency encoding gradient.

13. The MRI apparatus of claim 12, wherein the duration of the frequency encoding gradient overlaps with the duration of the phase encoding gradient.

15. A non-transitory computer-readable medium comprising instructions that, when executed, cause a processor to:

apply a phase encoding gradient corresponding to a phase encoding line in a circular Cartesian k-space, wherein an amplitude and a duration of the phase encoding gradient vary with a position of the phase encoding line in the circular Cartesian k-space; and

acquire k-space data along the phase encoding line in the circular Cartesian k-space by applying a frequency encoding gradient, wherein a duration of the acquiring k-space data varies with the position of the phase encoding line in the k-space.

16. The computer-readable medium of claim 15, wherein the closer the phase encoding line is to the center of the k-space, the longer the duration of the acquiring k-space data, and the further the phase encoding line is from the center of the k-space, the shorter the duration of the acquiring k-space data.

17. The computer-readable medium of claim 15, wherein closer the phase encoding line is to the center of the k-space, the shorter the duration of the phase encoding gradient, and the further the phase encoding line is from the center of the k-space, the longer the duration of the phase encoding gradient.

18. The computer-readable medium of claim 15, wherein the phase encoding line with the maximum amplitude of the phase encoding gradient is between the phase encoding line the closest to the center of the k-space and the phase encoding line the furthest to the center of the k-space.

19. The computer-readable medium of claim 15, wherein the duration of the frequency encoding gradient does not change with the phase encoding line, and the duration of acquiring the k-space data is a portion of the duration of the frequency encoding gradient.

20. The computer-readable medium of claim 15, wherein the duration of the frequency encoding gradient overlaps with the duration of the phase encoding gradient.