Method for two-dimensional correlation magnetic resonance spectroscopy

1. A method for directing a magnetic resonance imaging (MRI) system to sample k-space to acquire multi-dimensional spectral data, the steps of the method comprising:

directing the MRI system to perform a pulse sequence that causes the MRI system to:

apply an excitatory radio frequency (RF) pulse;

apply a series of gradient-modulated low-power adiabatic RF pulses during which scalar coupling occurs;

apply before the series of gradient-modulated low-power adiabatic RF pulses and after the excitatory RF pulse, a first RF pulse;

apply after the series of gradient-modulated low-power adiabatic RF pulses, a second RF pulse;

apply before the first RF pulse and after the excitatory RF pulse, a first coherence transfer pathway (“CTP”) gradient;

apply after the second RF pulse, a second CTP gradient;

acquire multi-dimensional spectral data by sampling k-space following the second CTP gradient; and

wherein the first and second RF pulses are employed to produce longitudinal mixing during the scalar coupling, and the first and second CTP gradients are employed to select a coherence transfer pathway.

2. The method as recited in claim 1 in which the polarity of the second CTP gradient is alternated such that an echo-antiecho acquisition is performed.

3. The method as recited in claim 2 in which the polarity of the first RF pulse is alternated relative to the polarity of the second CTP gradient to facilitate the echo-antiecho acquisition.

4. The method as recited in claim 1 in which the series of gradient-modulated low-power adiabatic pulses include GOIA-W(16,4) gradient-modulated RF pulses.

5. The method as recited in claim 1 in which the first RF pulse is a first adiabatic RF pulse and the second RF pulse is a second adiabatic RF pulse.

6. The method as recited in claim 5 in which the first and second adiabatic RF pulses include BIR-4 pulses.

7. The method as recited in claim 1 in which the excitatory RF pulse is a BIR-4 pulse.

8. The method as recited in claim 1 in which the pulse sequence further causes the MRI system to perform at least one of a LASER localization, a PRESS localization, and a STEAM localization technique.

9. The method as recited in claim 1 in which a volume-of-interest from which the multi-spectral data is acquired is spatially localized in three-dimensions by the series of gradient-modulated low-power adiabatic RF pulses, and in which the series of gradient-modulated low-power adiabatic RF pulses include a first set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along an x-gradient axis, a second set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along a y-gradient axis, and a third set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along a z-gradient axis.

10. The method as recited in claim 9 in which the series of gradient-modulated low-power adiabatic RF pulses includes an MLEV-16 composite pulse.

11. The method as recited in claim 10 in which the first set of gradient-modulated low-power adiabatic RF pulses includes four gradient-modulated low-power adiabatic RF pulses, the second set of gradient-modulated low-power adiabatic RF pulses includes four gradient-modulated low-power adiabatic RF pulses, and the third set of gradient-modulated low-power adiabatic RF pulses includes eight gradient-modulated low-power adiabatic RF pulses.

12. The method as recited in claim 1 in which the multi-dimensional spectral data is acquired using a constant-density spiral acquisition scheme.

13. The method as recited in claim 1 in which the pulse sequence further causes the MRI system to apply a first set of spoiler gradients after the first RF pulse and before the series of gradient-modulated low-power adiabatic RF pulses and to apply a second set of spoiler gradients after the series of gradient-modulated low-power adiabatic RF pulses and before the second RF pulse.

14. The method as recited in claim 1 in which the series of gradient-modulated low-power adiabatic RF pulses includes an MLEV-16 composite pulse.

15. A method for producing a two-dimensional spectrum with a magnetic resonance spectroscopy (MRS) system, the steps of the method comprising:

a) applying a radio frequency (RF) pulse with the MRS system;

b) applying a composite pulse sequence for mixing, the composite pulse sequence including a series of gradient-modulated low-power adiabatic RF pulses;

c) applying RF pulses before and after the composite pulse sequence to induce longitudinal magnetization transfer;

d) acquiring two-dimensional spectral data following the composite pulse sequence; and

e) reconstructing from the two-dimensional spectral data, a two-dimensional spectrum.

16. The method as recited in claim 15 in which the MRS system includes a magnetic resonance imaging (MRI) system.

17. The method as recited in claim 15 in which the composite pulse sequence is an MLEV-16 pulse sequence.

18. The method as recited in claim 15 further comprising applying a localization pulse sequence before acquiring the two-dimensional spectral data, the localization pulse sequence including at least one of a LASER pulse sequence, a PRESS pulse sequence, and a STEAM pulse sequence.

19. The method as recited in claim 15 in which the composite pulse sequence is configured to localize a volume-of-interest by including a first set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along an x-gradient axis, a second set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along a y-gradient axis, and a third set of gradient-modulated low-power adiabatic RF pulses applied concurrently with gradients along a z-gradient axis.

20. The method as recited in claim 15 further comprising applying a coherence transfer pathway gradient before and after the composite pulse sequence to select a coherence transfer pathway.