Methods for nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) measurements using long-lived states

A method for nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) measurements, includes creation of enhanced polarization of nuclei of a first kind within a sample in a magnetic field at cryogenic temperatures and transfer of the polarized sample to room temperature. The enhanced polarization of nuclei of the first kind is thereby transformed into long-lived states (LLS) of nuclei of a second kind and these LLS are sustained. The LLS is at least partially converted into observable magnetization and an NMR or MRI measurement is carried out. The method allows one to extend the time needed between hyperpolarized magnetization and NMR detection.