KINETICS OF THE INVIVO P-31-H-1 NUCLEAR OVERHAUSER EFFECT OF THE HUMAN-CALF-MUSCLE PHOSPHOCREATINE RESONANCE

In 31P1H double-resonance experiments in a 1.5 T whole-body MR system, we observed in vivo the truncated driven, transient, and steady-state 31P-1H nuclear Overhauser effect of the phosphocreatine resonance in 31P MR spectra of human gastrocnemius muscle. Maximum signal enhancements of 0.52 ± 0.01, 0.20 ± 0.01, and 0.79 ± 0.02 were measured, respectively. Fitting the data with theoretical functions which solve the multispin Solomon equations for N protons (S spins) dipolar coupled to a 31P nucleus (I spin) yields cross-relaxation times 2 [Σi=1-N ] in the order of 20 s. In vivo experiments are feasible for studying relaxation mechanisms in coupled 31P1H spin systems in intact tissue. © 1992.