Quantitation of localized P-31 magnetic resonance spectra based on the reciprocity principle

There is a need for absolute quantitation methods in P-31 magnetic resonanc e spectroscopy, because none of the phosphorous-containing metabolites is n ecessarily constant in pathology. Here, a method for absolute quantitation of in vivo P-31 MR spectra that provides reproducible metabolite contents i n institutional or standard units is described. It relies on the reciprocit y principle, i.e., the proportionality between the B-1 field map and the ma p of reception strength for a coil with identical relative current distribu tions in receive and transmit mode. Cerebral tissue contents of P-31 metabo lites were determined in a predominantly white matter-containing location i n healthy subjects. The results are in good agreement with the literature a nd the interexamination coefficient of variance is better than that in most previous studies. A gender difference found for some of the 31P metabolite s may be explained by different voxel composition. (C) 2001 Academic Press.