Measurement of the acute metabolic response to hypoxia in rat tumours in vivo using magnetic resonance spectroscopy and hyperpolarised pyruvate.

Purpose: To estimate the rate constant for pyruvate to lactate conversion in tumours in response to a hypoxic challenge, using hyperpolarised (13)C1-pyruvate and magnetic resonance spectroscopy.

Methods And Materials: Hypoxic inspired gas was used to manipulate rat P22 fibrosarcoma oxygen tension (pO2), confirmed by luminescence decay of oxygen-sensitive probes. Hyperpolarised (13)C1-pyruvate was injected into the femoral vein of anaesthetised rats and slice-localised (13)C magnetic resonance (MR) spectra acquired.

Kinetic modeling of hyperpolarized (13)C pyruvate metabolism in tumors using a measured arterial input function.

Mathematical models are required to estimate kinetic parameters of [1-(13)C] pyruvate-lactate interconversion from magnetic resonance spectroscopy data. One- or two-way exchange models utilizing a hypothetical approximation to the true arterial input function (AIF), (e.g.