SPIN-ECHO METHODS FOR THE DETERMINATION OF P-31 TRANSVERSE RELAXATION-TIMES OF THE ATP NMR SIGNALS IN-VIVO

P-31 magnetic resonance spectroscopy (MRS) examinations of the calf mu scles of healthy volunteers were performed to determine T-2 of the cou pled ATP signals by use of the Hahn spin-echo and the frequency-select ive spin-echo method. Additional measurements with the J-coupling refo cused double echo are presented. The most reliable determination of T- 2 relaxation times is possible with the frequency-selective spin echo. The other methods yield substantially wrong results. Theoretical expl anations are given how J-coupling and pulse-angle deviations affect th e signals and therefore the T-2 determinations. The calculations for a weakly coupled homonuclear AX spin system are shown because they demo nstrate most of the relevant facts. In addition, some important result s for a homonuclear AMX spin system, which the ATP is considered to be , are given.