3D Creatine Kinase Imaging (CKI) for In Vivo Whole-Brain Mapping of Creatine Kinase Reaction Rates with P-Magnetization Transfer MR Fingerprinting.

The creatine kinase (CK) is a key enzyme involved in brain bioenergetics, playing a key role in brain function and the pathogenesis of neurological and psychiatric diseases, but imaging its activity noninvasively in the human brain in vivo remains a significant challenge. This study aims to advance the magnetization transfer (MT)- P magnetic resonance fingerprinting (MRF) for 3D Creatine Kinase Imaging (CKI). The method was implemented and validated on a clinical 7 Tesla MRI scanner. It enables whole-brain mapping of CK reaction rates for the first time, showing robust reproducibility for 25-minute scan sessions. CKI acquisition also provided simultaneous mapping of adenosine triphosphate and phosphocreatine concentration ratios, phosphocreatine longitudinal relaxation time, and maps. Furthermore, a functional CKI (fCKI) study demonstrated the first CK activation map in response to visual stimulation, revealing a mean 15% increase in CK rates in the visual cortex. The novel imaging modalities, CKI and fCKI, have the potential to offer new insights into brain bioenergetics both at rest and during activity.