LOCALIZED SPECTROSCOPY FROM ANATOMICALLY MATCHED COMPARTMENTS - IMPROVED SENSITIVITY AND LOCALIZATION FOR CARDIAC P-31 MRS IN HUMANS

Several pioneering studies have demonstrated that localized P-31 NMR s pectroscopy of the human heart might become an important diagnostic to ol in cardiology. The main limitation is due to the low sensitivity of these experiments, allowing only crude spatial resolution. We have im plemented a three-dimensional version of SLOOP (''spectral localizatio n with optimal pointspread function'') on a clinical instrument, SLOOP takes advantage of all available a priori information to match the si ze and the shape of the sensitive volumes to the anatomical structures in the examined subject. Thus, SLOOP reduces the contamination from a djacent organs and improves the sensitivity compared to conventional t echniques such as ISIS or chemical shift imaging (CSI). Initial studie s were performed on six healthy volunteers at 1.5 T. The good localiza tion properties are demonstrated by the absence of resonances from blo od in the heart spectra, and by PCr-free spectra from the liver. Compa red to conventional CSI, the signal-to-noise ratio of the SLOOP heart spectra was improved by approximately 30%. Taking into account the var ying excitation angle in the inhomogeneous B-1 field of the surface co il, the SLOOP model computes the local spin saturation at every point in space. Therefore, no global saturation correction is required in th e quantitative evaluation of local spectra. In this study, we found a PCr/gamma-ATP ratio in the left ventricular wall of 1.90 +/- 0.33 (mea n +/- standard deviation), (C) 1998 Academic Press.