Molar Quantitation of Hepatic Metabolites Zn Vivo in Proton-decoupled, Nuclear Overhauser Effect Enhanced 31P

Proton decoupling and nuclear Overhauser effect (NOE) enhancement significantly improve the signal-to-noise ratio and enhance resolution of metabolites in in vivo 31P MRS. We obtained proton-decoupled, NOE-enhanced, phospholipid-saturated 31P spectra localized to defined regions within the normal liver using three-dimensional chemical shift imaging. Proton-decoupling resulted in the resolution of two major peaks in the phosphomonoester (PME) region, three peaks in the phosphodiester (PDE) region and a diphosphodiester peak. In order to obtain molar quantitation, we measured the NOE of all hepatic phosphorus resonances, and we corrected for saturation effects by measuring hepatic metabolite TI using the variable nutation angle method with phase-cycled, B,independent rotation, adiabatic pulses. After corrections for saturation effects, NOE enhancement, B , variations and point spread effects, the following mean concentrations (mmol/l of liver) (kSD) were obtained: