The singlet-contrast MRI experiments shown in Fig. demonstrate that despite the low concentration of the metabolites present (approximately 10 3 times lower than the concentration of H2O molecules), this technique can be used to suppress the water background signal and image metabolic flux. A FLASH sequence with centric reordering was used here as a convenient way to utilize the hyperpolarized magnetization generated by the OPE sequences, as only a small fraction of magnetization is used for the acquisition of each line in k-space. However, other imaging techniques such as rapid imaging with refocused echoes (RARE) or echo planar imaging (EPI) could be utilized for this experiment. In the current work, no slice selection was applied. This can be readily achieved in the case of OPE-45 where slice selection can be done in a standard way in the imaging part of the sequence, but is more complex for the case of OPE-s90 which uses frequency-selective excitation pulses, as the slice-selection gradient necessarily produces a large frequency distribution, making frequency selection challenging. It would however be possible to use a slice selective 180 refocusing pulse in the OPE sequence.