Method for reducing artifacts in magnetic resonance imaging

1. A method for reducing the appearance of an artifact in a magnetic resonance image of an object comprising:

applying an excitation radiofrequency (RF) pulse simultaneously with a gradient (G yt ) along a non-slice-selection axis and a slice selection gradient (G z ), and

subsequently applying a slice-selective refocusing radiofrequency (RF) pulse;

wherein G yt tilts the image slice selected by the excitation RF pulse by an angle Θ y relative to the image slice selected by the refocusing RF pulse.

2. A method for reducing the appearance of an artifact in a magnetic resonance image of an object comprising:

(a) applying to the object an excitation radiofrequency (RF) pulse simultaneously with a first gradient (G yt ) and a second gradient (G z ); and

(b) subsequently applying to the object a third gradient (G ytr ) and a fourth gradient (G zr ) and then applying a slice-selective refocusing RF pulse;

(c) acquiring magnetic resonance data from the object;

wherein G yt comprises a gradient applied along a non-slice-selection axis and G z comprises a slice selection gradient applied along the z-axis such that the image slice selected by the excitation RF pulse is tilted by an angle Θ y relative to the image slice selected by the refocusing RF pulse; and

wherein G ytr comprises a third gradient along the non-slice-selection axis and G zr comprises a slice refocusing gradient or a combination of a slice refocusing gradient and a slice selection crusher gradient.

3. The method of claim 2 further comprising: generating and displaying an image based on the acquired magnetic resonance data.

4. The method of claim 3 , further comprising, after generating the image based on the acquired magnetic resonance data and prior to displaying the image:

(a) identifying a residual artifact in the image;

(b) fitting the artifact in the shape of a line;

(c) executing an operation that zeroes out signal intensities within the line of (b) in the phase-encoding direction of the image; and

(d) executing an operation that interpolates the zeroed signal intensities from data represented as pixels immediately adjacent to the line of (b).

5. The method of claim 2 wherein the G yt and G z are selected such that angle Θ y is from about 1° to about 3°.

6. The method of claim 2 wherein the appearance of the artifact is reduced by more than 50%.

7. The method of claim 6 wherein the appearance of the artifact is reduced by more than 75%.

8. The method of claim 2 wherein the slice selected by the refocusing RF pulse comprises a thickness of about 2 mm to 7 mm.

9. The method of claim 8 , wherein the slice selected by the refocusing RF pulse comprises a thickness of about 3 mm to 6 mm.

10. The method of claim 2 wherein the non-slice-selection axis is a phase-encoding axis.

11. The method of claim 2 wherein the non-slice-selection axis is a readout axis.

12. An article of manufacture including a non-transitory computer readable medium having instructions stored thereon that, in response to execution by a computing device, cause the computing device to control a magnetic resonance imaging (MRI) apparatus to perform operations comprising:

(a) applying an excitation radiofrequency (RF) pulse simultaneously with a first gradient (G yt ) and a second gradient (G z ) to an object in the MRI apparatus;

(b) applying to the object a third gradient (G ytr ) and a fourth gradient (G zr ) and then applying a slice-selective refocusing RF pulse; and

(c) acquiring magnetic resonance data from the object;

wherein G yt comprises a gradient applied along a non-slice-selection axis and G z comprises a slice selection gradient applied along the z-axis such that the slice selected by the excitation RF pulse is tilted by an angle Θ y relative to the slice selected by the refocusing RF pulse; and

wherein G ytr comprises a third gradient along the said non-slice-selection axis and G zr comprises a slice refocusing gradient or a combination of a slice refocusing gradient and a slice-selection crusher gradient.

13. The article of manufacture of claim 12 , wherein the instructions further causes the computing device to generate and display an image based on data acquired.

14. The article of manufacture of claim 13 , wherein the instructions further causes the computing device, after generating the image based on the acquired magnetic resonance data and prior to displaying the image, to:

(a) identify a residual artifact in the image;

(b) fit the artifact in the shape of a line;

(c) execute an operation that zeroes out signal intensities within the line of (b) in the phase-encoding direction of the image; and

(d) execute an operation that interpolates the zeroed signal intensities from data represented as pixels immediately adjacent to the line of (b).

15. A magnetic resonance imaging (MRI) apparatus comprising:

(a) an MRI system having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an radio frequency (RF) transceiver system and an RF switch controlled by a pulse generation module to transmit RF signals to an RF coil assembly to acquire MR images; and

(b) a computing device configured to:

(i) apply an excitation radiofrequency (RF) pulse simultaneously with a first gradient (G yt ) and a second gradient (G z ) to an object in the MRI apparatus;

(ii) apply to the object a third gradient (G ytr ) and a fourth gradient (G zr ) and then applying a slice-selective refocusing RF pulse; and

(iii) acquire magnetic resonance data from the object;

wherein G yt comprises a gradient applied along a non-slice-selection axis and G z comprises a slice selection gradient applied along the z-axis such that the slice selected by the excitation RF pulse is tilted by an angle Θ y relative to the slice selected by the refocusing RF pulse; and

wherein G ytr comprises a gradient along the said non-slice-selection axis and G zr comprises a slice refocusing gradient or a combination of a slice refocusing gradient and a slice-selection crusher gradient.