Diffusion MR of hyperpolarized 13C molecules in solution†
We combined the high MR signal enhancement achieved using dissolution dynamic nuclear polarization (DNP) with a pulsed gradient double spin echo diffusion MR sequence to rapidly and accurately measure the diffusion coefficients of various hyperpolarized 13C molecules in solution. Furthermore, with a diffusion-weighted imaging sequence we generate diffusion coefficient maps of multiple hyperpolarized metabolites simultaneously. While hyperpolarized experiments can measure rapid, non-equilibrium processes by avoiding signal averaging, continuous signal loss due to longitudinal relaxation (T1) complicates quantitation. By correcting for this signal loss, we demonstrate the feasibility of using hyperpolarized 13C diffusion-weighted MR to accurately measure real-time (seconds) molecular transport phenomena. Potential applications include rapidly measuring molecular binding, cellular membrane transport, in vivo metabolite distribution and establishing a magnetic field independent hyperpolarized parameter.