Purpose: The creatine kinase rate of metabolic adenosine triphosphate (ATP) synthesis is an important metabolic parameter but is challenging to measure in vivo due to limited signal-to-noise ratio and long measurement time. Theory and Methods: This study reports the implementation of an accelerated 31P Four Angle Saturation Transfer (FAST) method to measure the forward creatine kinase (CK) rate of ATP synthesis. Along with a high-field scanner (11.7 Tesla) and a small sensitive surface coil, the forward CK rate in the rat brain was measured in ∼5 min. Results: Under 1.2% isoflurane, the forward CK rate constant and metabolic flux were, respectively, kf,CK = 0.26 ± 0.02 s-1 and Ff,CK = 70.8 ± 4.6 μmol/g/min. As a demonstration of utility and sensitivity, measurements were made under graded isoflurane. Under 2.0% isoflurane, kf,CK = 0.16 ± 0.02 s-1 and Ff,CK = 41.0 ± 4.2 μmol/g/min, corresponding to a 38% and 42% reduction, respectively, relative to 1.2% isoflurane. By contrast, the ATP and phosphocreatine concentrations were unaltered. Conclusion: This study demonstrated the 31P FAST measurement of creatine kinase rate of ATP synthesis in rat brain with reasonable temporal resolution. Different isoflurane levels commonly used in animal models significantly alter the CK reaction rate but not ATP and phosphocreatine concentrations.
- High fields
- Metabolic flux
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging