An improved method for the detection of malignancy by proton NMR spectroscopy of plasma.

The ratio of intensity (RI) of the plasma lipid methyl proton NMR resonance from two Carr-Purcell-Meiboom-Gill spectra acquired with a short (2.4 msec) and long (120 msec) pulse delay time is proposed to provide a potentially more sensitive and less variable marker of human malignancy than the linewidth parameter previously suggested (E.T. Fossel, J.M. Carr, and J. McDonagh (1986) N. Engl. J. Med. 315, 1369-1376). Linewidth and transverse (T2) relaxation data are presented which demonstrate that the observed correlation between methyl and methylene lipid linewidth and the methyl RI parameter arises from a combination of T2 differences and the relative amounts that fast- and slow-relaxing components contribute to the composite methyl resonance.