ESTIMATION OF METABOLITE CONCENTRATIONS FROM LOCALIZED IN-VIVO PROTONNMR-SPECTRA

The LCModel method analyzes an in vivo spectrum as a Linear Combinatio n of Model spectra of metabolite solutions in vitro. By using complete model spectra, rather than just individual resonances, maximum inform ation and uniqueness are incorporated into the analysis. A constrained regularization method accounts for differences in phase, baseline, an d lineshapes between the in vitro and in vivo spectra, and estimates t he metabolite concentrations and their uncertainties. LCModel is fully automatic in that the only input is the time-domain in vivo data. The lack of subjective interaction should help the exchange and compariso n of results. More than 3000 human brain STEAM spectra from patients a nd healthy volunteers have been analyzed with LCModel. N-acetylasparta te, cholines, creatines, myo-inositol, and glutamate can be reliably d etermined, and abnormal levels of these or elevated levels of lactate, alanine, sryllo-inositol, glutamine, or glucose clearly indicate nume rous pathologies. A computer program will be available.