High Resolution Sodium Imaging of Human Brain at 7T

The feasibility of high resolution sodium MRI on human brain at 7T was demonstrated in this study. A three-dimensional anisotropic resolution data acquisition was used to address the challenge of low SNR associated with high resolution. Ultrashort echo time sequence was employed for the anisotropic data acquisition. Phantoms and healthy human brains were studied on a whole-body 7T MRI scanner. Sodium images were obtained at two high nominal in-plane resolutions (1.72 and 0.86 mm) at slice thickness 4 mm. SNR in the brain image (cerebrospinal fluid) was measured as 14.4 and 6.8 at the two high resolutions, respectively. The actual in-plane resolution was measured as 2.9 and 1.6 mm, 69–86% larger than their nominal values. The quantification of sodium concentration on the phantom and brain images enabled better accuracy at the high nominal resolutions than at the low nominal resolution 3.44 mm (measured resolution 5.5 mm) due to the improvement of in-plane resolution.