Selective detection of ordered sodium signals via the central transition

Given the correlation between the concentrations of ordered 23Na and the onset of tissue disorders, the ability to select the signal from ordered 23Na over that of free 23Na is of particular importance and can greatly enhance the potential of 23Na-MRI as a diagnostic tool. Here, we describe a simple method that selectively detects the central transition of ordered sodium while minimizing the signal from free sodium. Our method relies upon the influence of the quadrupolar interaction on nutation frequencies and may also benefit solid-state imaging experiments. Both a liquid crystalline environment and a cartilage sample are used to demonstrate a clean separation between anisotropic and isotropic regions in the experiments.