Abstract: The invention provides a method of proton-electron double-resonance magnetic resonance imaging in which a sample containing paramagnetic material is subjected to a polarizing magnetic field during a polarization period, a subsequent evolution period and thereafter a detection period, and the sample is subjected during the evolution period to radio-frequency radiation, at a frequency appropriate to the polarizing magnetic field then appertaining, so as to excite EPR resonance in the paramagnetic material, wherein during the detection period the sample is subjected to a series of NMR interrogating signals to derive therefrom a corresponding series of NMR image signals for combination in a complete NMR image.