Sensitive-volume localization for in vivo NMR using heteronuclear spin-echo pulse sequences.
Heteronuclear spin-echo techniques, which require the application of an inversion pulse on the second heteronucleus, may be applied with inhomogeneous rf coils such as surface coils. There are important applications in vivo including the detection of 13C-labeled and 15N-labeled metabolites in the 1H NMR spectrum. Using a depth pulse scheme for the 1H spin-echo sequence, and particular single or composite 13C pulses, two sensitive volumes are generated by the 1H and the 13C rf coils and signal is only obtained from the region of overlap between the two sensitive volumes. This method of signal localization for in vivo applications can be extended to 1H homonuclear editing and selective polarization-transfer techniques. The off-resonance characteristics of several different composite pulses are explored.
D000818:Animals; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D051381:Rats