Off-Resonance Effects of the Radiofrequency Pulses Used in Spectral Editing with Double-Quantum Coherence Transfer

✍ Scribed by Hao Lei; James Peeling

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 102 KB
• Volume: 144
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.2000.2053

✦ Synopsis

Spectral editing using gradient selected double-quantum (DQ) coherence transfer is often used for the selective observation of metabolites in vivo. In attempting to optimize the detection sensitivity of a conventional DQ spectral editing sequence, the effects of using radiofrequency (RF) pulses that are not at the resonance frequency of the observed peaks were investigated both theoretically and experimentally. The results show that spectral editing using pulses at the frequency of the observed resonance does not necessarily give the optimal detection sensitivity. At 7 T, the detection sensitivity of lactate observed using a DQ editing method can be increased by up to 30% by setting the RF pulses off resonance at the proper frequency. The results also suggest that slice selective RF pulses used in DQ spectral editing combined with PRESS localization may have slice profiles different from those when the same pulses are used for standard PRESS spatial localization.