Systems and methods for magnetic resonance imaging

• US 20070249929A1
• Filed: 04/02/2007
• Published: 10/25/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah (State of Utah)
• Inventors: Parker, Dennis, Kholmovski, Evgueni, Choi, Kim, Jeong, Eun-Kee
• Granted Patent: US 8,406,849 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/4806 Functional imaging of brain activation
• 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]
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/56341 Diffusion imaging
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• CPC Class Codes: G01R 33/56536 due to magnetic susceptibility variations
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

Methods and apparatus for operating an MRI system is provided. The disclosure provides a diffusion-prepared driven-equilibrium preparation for an imaging volume and acquiring 3-dimensional k-space data from said prepared volume by a plurality of echoplanar readouts of stimulated echoes. An excitation radio-frequency signal and first and second inversion RF signals are provided to define a field-of-view (FOV).

Claims

1. A method for operating an MRI system, comprising:

providing a diffusion-prepared driven-equilibrium preparation for an imaging volume; and

acquiring 3-dimensional k-space data from said imaging volume by a plurality of echoplanar readouts of stimulated echoes.

2. The method of claim 1, wherein said diffusion-prepared driven-equilibrium preparation comprises a single diffusion-prepared driven-equilibrium preparation.

3. The method of claim 1, wherein said 3-dimensional k-space data comprises a raw data that has not been transformed.

4. The method of claim 1, wherein said MRI system is operated for diffusion-weighted MR imaging (DWI).

5. The method of claim 1, wherein said MRI system is operated for diffusion tensor MR imaging (DTI).

6. The method of claim 1, wherein said acquiring of 3-dimensional k-space data comprises acquiring substantially entire 3-dimensional k-space data.

7. A method for interleaved MR imaging, comprising:

providing an excitation radio-frequency (RF) signal;

providing first and second inversion RF signals to define a field-of-view (FOV).

8. The method of claim 7, wherein said first and second inversion RF signals comprise first and second inversion RF pulses.

9. The method of claim 8, wherein said first inversion RF pulse is applied substantially immediately after said excitation RF signal.

10. The method of claim 8, wherein said first and second inversion RF pulses are separated by a time approximately 5 ms or larger.

11. The method of claim 8, wherein said first and second inversion RF pulses are separated by a time less than about 5 ms.

12. The method of claim 8, wherein said first and second inversion RF pulses are separated by a time more than about 5 ms.

13. The method of claim 8, further comprising providing slice-selective gradients that are selected such that magnetization within said FOV is substantially preserved while magnetization external to said FOV is substantially suppressed, thereby allowing magnetization in each of a plurality of slices to be substantially maintained in its equilibrium state while exciting and imaging one or more others of said plurality of slices.

15. The system of claim 12, wherein said diffusion-prepared driven-equilibrium preparation comprises a single diffusion-prepared driven-equilibrium preparation.

16. The system of claim 12, wherein said 3-dimensional k-space data comprises a raw data that has not been transformed.

17. The system of claim 12, wherein said MRI apparatus is for diffusion-weighted MR imaging (DWI).

18. The system of claim 12, wherein said MRI apparatus is configured for diffusion tensor MR imaging (DTI).

19. The system of claim 12, wherein said acquiring of 3-dimensional k-space data comprises acquiring substantially entire 3-dimensional k-space data.

21. The system of claim 18, wherein said first and second inversion RF signals comprise first and second inversion RF pulses.

22. The system of claim 19, wherein said first inversion RF pulse is applied substantially immediately after said excitation RF signal.

23. The system of claim 19, wherein said first and second inversion RF pulses are separated by a time approximately 5 ms or larger.

24. The system of claim 19, wherein said first and second inversion RF pulses are separated by a time less than about 5 ms.

25. The system of claim 19, wherein said first and second inversion RF pulses are separated by a time more than about 5 ms.

26. The system of claim 19, wherein said one or more instructions further includes an instruction for providing slice-selective gradients that are selected such that magnetization within said FOV is substantially preserved while magnetization external to said FOV is substantially suppressed, thereby allowing magnetization in each of a plurality of slices to be substantially maintained in its equilibrium state while exciting and imaging one or more others of said plurality of slices.

14. A control system for an MRI apparatus, comprising:

a control component configured to generate one or more instructions for;

providing a diffusion-prepared driven-equilibrium preparation for an imaging volume; and

acquiring 3-dimensional k-space data from said prepared volume by a plurality of echoplanar readouts of stimulated echoes.

20. A control system for an MRI apparatus, comprising:

a control component configured to generate one or more instructions for;

providing an excitation radio-frequency (RF) signal;

providing first and second inversion RF signals to define a field-of-view (FOV).

27. A method for correcting a motion artifact during MR imaging, comprising:

acquiring navigation data substantially together with imaging data;

determining whether to re-acquire said imaging data based on said navigation data; and

re-acquiring said imaging data based on said determination.

28. The method of claim 27, wherein said motion artifact is due to intra-shot motion.

29. The method of claim 27, wherein said motion artifact is due to inter-shot motion.

30. The method of claim 27, wherein said determining and re-acquiring are performed substantially real-time.

31. The method of claim 27, wherein said navigation data comprises 2D k-space navigation echoes, and wherein said determining comprises identifying value and position of the largest signal in said 2D k-space to see if either of said value or position is outside of a corresponding selected range.

32. The method of claim 27, wherein said MR imaging comprises a multi-average singleshot EPI operated as at least one of DWI, DTI, and fMRI.

33. The method of claim 27, wherein said MR imaging comprises at least one of spin-echo, multiple spin-echo, gradient-echo, and segmented gradient-echo.

34. A system for correcting a motion artifact during MR imaging, comprising:

a control component configured to generate one or more instructions for;

acquiring navigation data substantially together with imaging data;

determining whether to re-acquire said imaging data based on said navigation data; and

re-acquiring said imaging data based on said determination.

35. The system of claim 34, wherein said motion artifact is due to intra-shot motion.

36. The system of claim 34, wherein said motion artifact is due to inter-shot motion.

37. The system of claim 34, wherein said determining and re-acquiring are performed substantially real-time.

38. The system of claim 34, wherein said navigation data comprises 2D k-space navigation echoes, and wherein said determining comprises identifying value and position of the largest signal in said 2D k-space to see if either of said value or position is outside of a corresponding selected range.

39. The system of claim 34, wherein said MR imaging comprises a multi-average singleshot EPI operated as at least one of DWI, DTI, and fMRI.

40. The system of claim 34, wherein said MR imaging comprises at least one of spin-echo, multiple spin-echo, gradient-echo, and segmented gradient-echo.