MAGNETIC RESONANCE RELAXATION ALONG A FICTITIOUS FIELD

• US 20120286780A1
• Filed: 04/09/2012
• Published: 11/15/2012
• Est. Priority Date: 04/08/2011
• 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: Michaeli, Shalom, Sorce, Dennis J., Garwood, Michael G., Liimatainen, Timo, Mangia, Silvia
• Granted Patent: US 9,222,999 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: G01R 33/446 Multifrequency selective RF pulses, e.g. multinuclear acquisition mode spatially selective RF pulses G01R33/4833
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences

Abstract

A system includes a driving module, a processor, and a readout module. The driving module is configured to apply a perturbation to a sample. The processor is configured to define a plurality of different rotating frames relative to the perturbation, wherein each frame has a corresponding fictitious field. The readout module is coupled to the processor and is configured to generate an output based on relaxation of the sample as a function of the perturbation.

Claims

1. A system comprising:

a driving module configured to apply a perturbation to a sample;

a processor configured to define a plurality of different rotating frames of reference relative to the perturbation, wherein each frame has a corresponding fictitious field, the fictitious field produced by interaction of the plurality of different rotating frames of reference; and

a readout module coupled to the processor and configured to generate an output based on relaxation of spins of the sample as a function of the perturbation.

2. The system of claim 1 wherein the processor is configured to generate a frequency swept pulse.

3. The system of claim 1 wherein the driving module is configured to deliver a frequency swept pulse.

4. The system of claim 1 wherein the driving module is configured to apply a pulse train.

5. The system of claim 1 wherein the processor is configured to instantaneously flip the fictitious field.

6. The system of claim 1 further including at least one of a display or printer coupled to the readout module.

7. A method comprising:

applying a perturbation to a system;

defining a plurality of different rotating frames relative to the perturbation, wherein each frame has a corresponding fictitious field and wherein the plurality includes at least three; and

applying a readout module to the system after applying the perturbation.

8. The method of claim 7 wherein applying the perturbation to the system includes applying magnetic perturbation to a spin system.

9. The method of claim 7 wherein at least one fictitious field remains constant in at least one rotating frame.

10. The method of claim 7 wherein at least one fictitious field is time dependent.

11. The method of claim 7 further including decreasing relaxation of the spin system in a selected rotating frame of the plurality of different rotating frames.

12. The method of claim 7 further including generating a rotating frame rotary echo in the spin system.

13. The method of claim 7 further including locking magnetization of the system to a fictitious field of a selected rotating frame.

14. The method of claim 7 further wherein the fictitious field is non-stationary.

15. The method of claim 7 wherein applying the perturbation includes applying a frequency swept pulse.

16. The method of claim 7 wherein at least one fictitious field remains constant in amplitude.

17. The method of claim 7 wherein at least one fictitious field is time dependent.

18. The method of claim 7 wherein at least one fictitious field remains constant in direction.

19. A processor-implemented method for generating a magnetic resonance image, the method comprising:

selecting a rank for a fictitious frame of reference for imaging a region of interest;

generating a pulse sequence having a sweeping frequency and modulated amplitude and phase in which the effective field remains time invariant in the fictitious frame;

acquiring magnetic resonance data corresponding to relaxation of spins in the region of interest based on excitation from the pulse sequence; and

generating an image based on the acquired data.

20. The method of claim 19 wherein the pulse sequence is sub-adiabatic.

21. The method of claim 19 wherein the rank is greater than 2.