Correlation of Exercise Induced Changes in Cr CEST and 31P MRS in Human Calf Muscles

Feliks Kogan¹, Mohammad Haris¹, Anup Singh¹, Kejia Cai¹, Catherine DeBrosse¹, Ravi Prakash Reddy Nanga¹, Hari Hariharan¹, Ravinder Reddy¹

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.