Chemical Exchange Saturation Transfer Effects from Creatine Kinase Reaction Metabolites

Mohammad Haris¹, Anup Singh¹, Kejia Cai¹, Ravi Prakash Reddy Nanga¹, Catherine Debrosse¹, Hari Hariharan¹, Ravinder Reddy¹

Exchange rate (kex) and logarithmic dissociation constant (pKa) of amine protons of creatine (Cr), phosphocreatine (PCr) and adenosine-triphosphate (ATP) were calculated with an objective to explore the chemical-exchange-saturation-transfer-effects (CEST) of these metabolites. The kex of amine protons in Cr was found to be 7-8 times higher than PCr and ATP. Higher kex in Cr is associated with the low pKa value suggesting the faster dissociation of its amine protons compared to PCr and ATP. CEST imaging of these metabolites showed predominant CEST contrast from Cr. These results provide a new method to perform high resolution proton imaging of Cr without any contamination from PCr.