Tao Xu1, Dirk Mayer2, Meng Gu1, Yi-Fen Yen3, Edvin Johansson4, Jim Tropp5, Ralph Hurd3, Daniel Spielman2
1Department of Electrical Engineering, Stanford University, Stanford, CA, USA; 2Department of Radiology, Stanford University, Stanford, CA, USA; 3Global Applied Sciences Laboratory, GE Healthcare, Menlo Park, CA, USA; 4Medical Diagnostics R&D, GE Healthcare, Oslo, Norway; 5Global Applied Sciences Laboratory, GE Healthcare, Fremont, CA, USA
Hyperpolarized MRS of metabolically active substrates allows the study of both the injected substrate and downstream metabolic products in vivo. Nowadays, most dynamic studies have employed slice-select excitation pulses with small flip angles to measure the metabolic time curves following bolus injection of the hyperpolarized substrate. Constant metabolic exchange rates are typically assumed throughout the observation window. We developed a new technique for measuring Michaelis-Menten kinetics of hyperpolarized 13C1-pyruvate metabolism in a single bolus injection. The results clearly demonstrate the nonlinear relationship between metabolic exchange rates and pyruvate concentration.
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