Sensitive-volume localization for in vivo NMR using heteronuclear spin-echo pulse sequences.

Area of Science:

• Magnetic Resonance Imaging
• Biophysical Chemistry
• Medical Physics

Background:

• Heteronuclear spin-echo techniques are crucial for detecting metabolites in vivo.
• Inhomogeneous radiofrequency (RF) coils, like surface coils, can be utilized with these techniques.
• Applications include detecting 13C-labeled and 15N-labeled metabolites within the 1H NMR spectrum.

Purpose of the Study:

• To explore the application of heteronuclear spin-echo techniques with inhomogeneous RF coils.
• To demonstrate a method for signal localization in vivo using 1H and 13C RF coils.
• To investigate the extension of this localization method to other NMR techniques.

Main Methods:

• Utilized heteronuclear spin-echo sequences with an inversion pulse on the second heteronucleus.
• Employed a depth pulse scheme for the 1H spin-echo sequence.
• Used specific single or composite 13C pulses to generate two sensitive volumes.

Main Results:

• Demonstrated signal acquisition only from the overlapping region of 1H and 13C sensitive volumes.
• Showcased the successful application of the technique with inhomogeneous surface coils.
• Explored the off-resonance characteristics of various composite pulses.

Conclusions:

• Heteronuclear spin-echo techniques are viable with inhomogeneous RF coils for in vivo metabolite detection.
• The described signal localization method enhances specificity for in vivo NMR studies.
• The technique's adaptability extends to 1H homonuclear editing and selective polarization-transfer.