Improving Quantification of Hyperpolarized 13C-Pyruvate Metabolism Using Pyruvate Metabolite Specific bSSFP and Variable Flip Angles

A pyruvate-specific bSSFP protocol was defined, based on prior work, demonstrating increased signal efficiency over GRE sequences. Monte Carlo simulations evaluated signal efficiency and kinetic performance of potential flip angle schemes. A sigmoid-based flip scheme, varying from 5 to 80 degrees, showed greatest performance of kPL estimation compared to simulated GRE and constant flip angle bSSFP. Small animal studies validated the expected signal increase and kPL estimation, with resulting kinetic parameter maps showing consistency among methods and qualitative noise reduction.