Thermal annihilation of photo-induced radicals following dynamic nuclear polarization to produce transportable frozen hyperpolarized (13)C-substrates

Hyperpolarization via dynamic nuclear polarization (DNP) is pivotal for boosting magnetic resonance imaging (MRI) sensitivity and dissolution DNP can be used to perform in vivo real-time (13)C MRI. The type of applications is however limited by the relatively fast decay time of the hyperpolarized spin state together with the constraint of having to polarize the (13)C spins in a dedicated apparatus nearby but separated from the MRI magnet. We herein demonstrate that by polarizing (13)C with photo-induced radicals, which can be subsequently annihilated using a thermalization process that maintains the sample temperature below its melting point, hyperpolarized (13)C-substrates can be extracted from the DNP apparatus in the solid form, while maintaining the enhanced (13)C polarization. The melting procedure necessary to transform the frozen solid into an injectable solution containing the hyperpolarized (13)C-substrates can therefore be performed ex situ, up to several hours after extraction and storage of the polarized solid.