Abstract
Double resonance techniques such as INEPT (insensitive nuclei enhanced by polarization transfer) and __J__CP (J cross‐polarization) have previously been applied in vitro to enhance the SNR of low‐sensitivity nuclei and detect altered metabolism, for example, with ^13^C magnetic resonance spectroscopy (MRS), where the ^1^H‐^13^C scalar couplings are of the order of 130 Hz. The aim of the present study was to investigate the potential advantage of using __J__CP for the detection of phosphomonoesters (PME) and phosphodiesters (PDE) with ^31^P MRS in vivo. These metabolites are involved in membrane metabolism and their concentration is altered in tumors and other pathologies. __J__CP has been implemented and compared with INEPT and pulse‐and‐acquire in vivo both in unlocalized and in localized spectra in order to select the optimum method for in vivo applications for PME and PDE detection. The results suggest that __J__CP can give up to 20% more signal in the PME region and up to 70% more signal in the PDE region, with 20 to 70% lower power deposition than INEPT. Such enhancement could be used to reduce the measurement times for equivalent signal‐to‐noise ratios. The __J__CP sequence is, however, slightly more sensitive than INEPT to RF field inhomogeneities, as predicted from theory. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.