1Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, United States
Creatine, a key component of muscle energy metabolism, exhibits a chemical exchange saturation transfer effect (CrCEST) between its amine group and bulk water. We characterized CrCEST for the spatial mapping of free creatine in imaging muscle energy metabolism. In healthy human subjects, following mild plantar flexion exercise, increases in CrCEST were observed in the posterior compartment of the leg which recovered exponentially back to baseline. This technique exhibited good spatial resolution and was able to differentiate differences in muscle utilization among subjects. CrCEST results were compared with 31P MRS results showing good agreement in the recovery kinetics of CrCEST and PCr signal following exercise.