Figure 2.

³¹P-MRS spectra of a model solution containing expected physiological concentrations of ATP, P_i, PCr, and PArg. The model solution consisted of 30 mM PCr, 10 mM Pi, 30 mM PArg, and 8 mM ATP in 0.4 ml of distilled water. In solution, PArg was well resolved from PCr and γATP with a chemical shift of 0.47 ppm relative to PCr. The model solution was used to determine the appropriate spectral analysis package for the analysis of both phantom and mouse skeletal muscle data with the minimal amount of user bias. The solid line is the best fit to the free induction decay using a Hankel single value decomposition algorithm (18), which avoided peak selection and the use of previous knowledge.