Concentrations of human cardiac phosphorus metabolites determined by SLOOPP-31 NMR spectroscopy

Human cardiac P-31 nuclear magnetic resonance (NMR) spectra are usually qua ntified in relative terms, i.e., the ratio of metabolite signals is calcula ted. If P-31 NMR spectroscopy of the heart is to emerge as a clinically rel evant diagnostic modality, reliable quantification of absolute concentratio ns of P-31 metabolites is required. We applied spectral localization with o ptimal point spread function (SLOOP) P-31 NMR spectroscopy to measure absol ute concentrations of phosphocreatine (PCr) and adenosine triphosphate (ATP ) in human myocardium. The accuracy of the quantification was first validat ed in a phantom study. Seven healthy volunteers (aged 19-29 years) were the n examined at 1.5 T using a nominal spatial resolution of 25 mL. SLOOP allo wed us to obtain localized spectra from compartments anatomically matched t o the left ventricular wall. The a priori knowledge of the anatomical struc ture was obtained from H-1 images. The spatially varying effects of saturat ion, off-resonance, and sensitivity were considered during the reconstructi on process. Metabolites were quantified with reference to an external P-31 standard. Concentrations of 9.0 +/- 1.2 and 5.3 +/- 1.2 mmol/kg wet wt (mea n +/- SD, n = 9) were determined for PCr and ATP in normal heart, respectiv ely. The influence of nuclear Overhauser enhancement on metabolite quantifi cation is discussed. (C) 1999 Wiley-Liss, Inc.