Pulse gap cycling for improved swift

• US 8,933,698 B2
• Filed: 08/07/2013
• Issued: 01/13/2015
• Est. Priority Date: 04/01/2010
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Corum, Curtis A., Idiyatullin, Djaudat S., Moeller, Steen, Garwood, Michael G.
• Primary Examiner(s): Vargas, Dixomara
• Application Number:
  US13/961,042
• Publication Number:
  US 20130320980A1
• Time in Patent Office: 524 Days
• Field of Search: 324300-322
• US Class Current: 324/307
• CPC Class Codes: G01R 33/4641 Sequences for NMR spectroscopy of samples with ultrashort relaxation times such as solid samples
• CPC Class Codes: G01R 33/4816 NMR imaging of samples with ultrashort relaxation times such as solid samples, e.g. MRI using ultrashort TE [UTE], single point imaging, constant time imaging
• CPC Class Codes: G01R 33/4824 using a non-Cartesian trajectory
• CPC Class Codes: G01R 33/54 Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
• CPC Class Codes: G01R 33/565 Correction of image distortions, e.g. due to magnetic field inhomogeneities
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence

Abstract

A magnetic resonance image is produced by shifting a gap during acquisition of spin data for a specimen. The spin data is generated by a gapped excitation sequence.

Claims

1. A method comprising:

generating magnetic resonance (MR) data for a sample, the data corresponding to a plurality of interleaved spirals and based on a sequence including an excitation signal having a series of excitation gaps and a series of corresponding received spin system signal gaps, the excitation gaps or the received spin system signal gaps having a position that is cycled among a plurality of positions throughout a duration in at least one of the excitation signal or the received spin system signal; and

generating, using a processor, an image using the MR data.

2. The method of claim 1 wherein generating MR data includes using a SWIFT MR sequence.

3. The method of claim 1 wherein generating MR data includes using a fast 3D radial MR sequence.

4. The method of claim 1 wherein the sequence is configured to generate nearly simultaneous excitation and acquisition of spins within a gapped RF pulse.

5. The method of claim 1 wherein the gap is cycled within a predetermined period of time among discrete positions numbering at least one of 2, 3, 4, 5, 6, 8, 12, 16, and 24.

6. The method of claim 1 wherein the received spin system signal is oversampled.

7. The method of claim 1 wherein generating the image includes estimating overlap of a sideband relative to a baseband in the excitation signal.

8. The method of claim 1 wherein generating the image includes postprocessing using gridding with an oversampled Kaiser-Bessel kernel.

9. The method of claim 1 wherein generating the image includes post-processing using an average smoothness constraint.

10. The method of claim 1 wherein generating the image includes reversing a gradient.

11. The method of claim 1 wherein generating the image includes summing a plurality of data sets.

12. The method of claim 1 wherein a first spiral of the plurality of interleaved spirals has a first gap position and a second spiral of the plurality of interleaved spirals has a second gap position, and wherein the first gap position differs from the second gap position.

13. The method of claim 1 wherein the gap positions are cycled throughout the sequence.

14. The method of claim 1 wherein the gap positions are determined by a duty cycle.

15. The method of claim 14 wherein the gap positions are arranged in a subset of spirals selected from the plurality of interleaved spirals and further wherein the selected spirals are determined by the duty cycle.

16. The method of claim 14 further including receiving a user input and wherein the duty cycle is determined by the input.

17. The method of claim 1 wherein generating the MR data includes repeating a series of excitation gaps and the series of corresponding received spin system signal gaps.

18. The method of claim 1 wherein generating the MR data includes using a first order of gap positions and using a second order of gap positions, wherein the first order differs from the second order.

19. A non-transitory computer-readable medium having computer-executable instructions stored thereon for performing a method comprising:

generating magnetic resonance (MR) data for a sample, the data corresponding to a plurality of interleaved spirals and generated using an excitation sequence configured to image spins having a fast transverse relaxation rate and an acquisition sequence having a gap having a gap position that is time-cycled among a plurality of positions throughout a duration of the acquisition sequence; and

generating an image using the MR data.

20. The non-transitory computer-readable medium of claim 19 wherein the method includes summing at least four data sets.

21. The non-transitory computer-readable medium of claim 19 wherein the acquisition sequence is oversampled.

22. The non-transitory computer-readable medium of claim 19 wherein the gap positions are determined by a duty cycle.

23. The non-transitory computer-readable medium of claim 22 wherein the gap positions are arranged in a subset of spirals selected from the plurality of interleaved spirals and wherein the selected spirals are determined by the duty cycle.

24. The non-transitory computer-readable medium of claim 22 further including receiving a user input and wherein the duty cycle is determined by the input.

25. The non-transitory computer-readable medium of claim 19 wherein generating the MR data includes repeating the excitation sequence and repeating the acquisition sequence.

26. The non-transitory computer-readable medium of claim 19 wherein generating the MR data includes using a first order of gap positions and using a second order of gap positions, wherein the first order differs from the second order.

27. A system comprising:

a magnetic resonance scanner; and

a processor coupled to the scanner and configured to generate magnetic resonance (MR) data for a sample, the data corresponding to a plurality of interleaved spirals and based on a sequence including an excitation signal having a series of excitation gaps and a series of corresponding received spin system signal gaps, the excitation gaps or the received spin system signal gaps having a position that is cycled among a plurality of positions throughout a duration in at least one of the excitation signal or the received spin system signal;

an output device configured to at least one of generate an image based on the MR data or store the MR data.

28. The system of claim 27 wherein the processor is configured to implement a user-selected duty cycle, the duty cycle corresponding to the gap.

29. The system of claim 28 wherein the processor is configured to arrange the gap positions in a subset of spirals selected from the plurality of interleaved spirals and wherein the selected spirals are determined by the duty cycle.

30. The system of claim 28 further including an input device coupled to the processor, the input device configured to receive the user-selected duty cycle.

31. The system of claim 27 wherein a first spiral of the plurality of interleaved spirals has a first gap position and a second spiral of the plurality of interleaved spirals has a second gap position, and wherein the first gap position differs from the second gap position.

32. The system of claim 27 wherein the processor is configured to repeat a series of excitation gaps and the series of corresponding received spin system signal gaps.