Methods of magnetic resonance imaging (MRI) using contract agent solutions formed from the dissolution of hyperpolarised materials

The present invention provides a method of magnetic resonance investigation of a sample, preferably of a human or non-human animal body, said method comprising: (i) nuclear spin polarising a solid MR imaging agent (i.e. a material containing in its molecular structure a non-zero nuclear spin nucleus) by (a) spin refrigeration, or by, (b) irradiating with circularly polarised light; (ii) administering the nuclear spin polarised MR imaging agent to said sample, preferably after dissolution in a physiologically tolerable solvent and also preferably after separation form some or all of the paramagnetic species or chromophores; (iii) exposing said sample to a radiation at a frequency selected to excite nuclear spin transitions in selected nuclei therein, e.g. the spin polarised nuclei of the MR imaging agent; (iv) detecting magnetic resonance signals form said sample; and (v) optionally generating an image, dynamic flow data, diffusion data, perfusion data, physiological data (e.g. pH, pO2, pCO2, temperature or ionic concentrations) or metabolic data from said detected signals.