# US 10,768,252 B2 · Methods and systems for sampling k-space data in magnetic resonance imaging

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- Number: US 10,768,252 B2
- Document ID: US10768252B2
- Status: Granted
- Kind: B2
- Application number: 16/169,533
- Filed: 2018-10-24
- Published: 2020-04-30
- Granted: 2020-09-08
- Earliest claimed: 2018-10-24
- Assignees: General Electric Company
- Applicants: General Electric Company
- Inventors: Lisha Nie; Yongchuan Lai; Xuan Liu
- Web page: https://patentgrep.com/patent/US10768252B2

## CPC

- G01R 33/482: {using a Cartesian trajectory}
- G01R 33/4824: {using a non-Cartesian trajectory}
- 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)}
- G01R 33/561: by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
- 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)}
- 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]}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## 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

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 1)

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.

### Claim 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.

### Claim 9 (depends on 8)

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.

### Claim 10 (depends on 8)

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.

### Claim 11 (depends on 8)

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.

### Claim 12 (depends on 8)

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.

### Claim 13 (depends on 12)

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

### Claim 14 (depends on 1)

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.

### Claim 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.

### Claim 16 (depends on 15)

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.

### Claim 17 (depends on 15)

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.

### Claim 18 (depends on 15)

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.

### Claim 19 (depends on 15)

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.

### Claim 20 (depends on 15)

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