Comparison of methods for in vivo sodium imaging at 9.4 Tesla

Sodium imaging has the potential to become a powerful diagnostic technique in MRI. However the low tissue concentrations and the fast, biexponential signal decay of this nucleus make in vivo imaging very challenging. New sequences with ultra-short echo times, such as Twisted Projection Imaging (TPI), have to be used to enhance the low NMR sensitivity.

The primary goal of this project is to develop, implement, and compare fast imaging sequences for sodium. As the majority of these sequences do not acquire k-space on a Cartesian grid, their reconstruction is more complicated as compared to the standard Cartesian sequences. Furthermore non-Cartesian sequences are prone to introduce additional artefacts and hence deteriorate image quality. In summary, the optimal sequence should have a high NMR sensitivity, be robust against field inhomogeneities and should not lead to artefacts due to non-Cartesian sampling.

The image above shows the trajectories of some non-Cartesian 2D and 3D sequences used for sodium imaging.