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Quadrupolar-coupling-specific binomial pulse sequences for in vivo 23Na NMR and MRI
Christoffer Laustsen1, Steffen Ringgaard, Michael Pedersen
1MR Research Center, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|August 3, 2010
Summary
New pulse sequences enable selective detection of sodium-23 (23Na) in NMR and MRI. These sequences offer high specificity for quadrupolar couplings, improving tissue analysis by separating intra- and extracellular sodium.
Area of Science:
- Magnetic Resonance Imaging
- Nuclear Magnetic Resonance Spectroscopy
- Biophysics
Background:
- Sodium-23 (23Na) detection is crucial for in vitro NMR and MRI applications.
- Specific quadrupolar couplings of 23Na present challenges for selective detection.
- Distinguishing intra- and extracellular 23Na in tissues is vital for biological studies.
Purpose of the Study:
- To develop novel quadrupolar binomial pulse sequences for selective 23Na detection.
- To enhance specificity towards quadrupolar couplings of excited species.
- To improve the separation of intra- and extracellular 23Na in biological tissues.
Main Methods:
- Design and implementation of a series of quadrupolar binomial pulse sequences (e.g., 11, 121, 1331, 14641, 15101051).
- Utilizing flip angles smaller than 90 degrees and varied phase combinations for flexibility.
- Numerical simulations and experimental validation using NMR and MRI on a 7 T animal magnet system.
Main Results:
- Demonstrated high specificity for quadrupolar couplings, enabling selective 23Na excitation/suppression.
- Showcased robustness towards radiofrequency (rf) inhomogeneity.
- Successfully facilitated separation of intra- and extracellular 23Na in experimental models.
Conclusions:
- The presented quadrupolar binomial pulse sequences offer a flexible and specific approach for 23Na detection in NMR and MRI.
- These sequences allow for efficient control of central and satellite transitions, aiding in tissue analysis.
- The findings pave the way for advanced in vitro studies utilizing 23Na MRI and NMR.
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