RARE imaging of PCr in human forearm muscles.

Rapid acquisition with relaxation enhancement (RARE) sequences have been used to map the 31P phosphocreatine (PCr) signal in human forearms at 4.7 T. Signal-to-noise levels of approximately 10 were achieved from the major muscle groups in 5.5-minute scan times with a spatial resolution of 4 x 2 x 2 cm3. Exercise caused demonstrable reductions in PCr signal from activated muscles, which correlated with affected muscle groups in T2-weighted proton images. RARE imaging of the PCr signal at 4.7 T is feasible and, with technically achievable improvements in signal-to-noise ratio, should prove useful in studying energy metabolism in muscle and other organs.