COMPARISON OF METHODS FOR THE DETERMINATION OF ABSOLUTE METABOLITE CONCENTRATIONS IN HUMAN MUSCLES BY P-31 MRS

In order to determine metabolite concentrations in human skeletal musc les by in vivo P-31 MRS, different quantification methods were analyze d with regard to the accuracy and reproducibility of results and the s implicity of handling. Each quantification method comprised a calibrat ion strategy and a localization technique. Extensive in vivo and in vi tro tests showed that homonuclear phantom-based calibration strategies yielded significantly more accurate (lower systematic errors) and mor e reproducible (lower statistical errors) concentration estimates than heteronuclear strategies using internal water as a concentration stan dard. Additionally, the former strategies are easier to handle than th e latter. Localization with the volume-selective sequence ISIS yielded slightly more reproducible results than localization by surface coil. We conclude that phosphorus metabolite concentrations are determined most accurately with phantom-based calibration strategies in combinati on with ISIS localization (measurement errors almost-equal-to 5-7%).