Chemical shift sodium imaging in a mouse model of thromboembolic stroke at 9.4 T.

Purpose: To estimate changes in the ²³Na density and in the ²³Na relaxation time T₂* in the anatomically small murine brain after stroke. Materials and Methods: Three-dimensional acquisition weighted chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm³ was used for sodium imaging and relaxation parameter mapping. In vivo measurements of the mouse brain ( n = 4) were performed 24 hours after stroke, induced by microinjection of purified murine thrombin into the right middle cerebral artery. The measurement time was 14 minutes in one mouse and 65 minutes in the other three. An exponential fit estimation of the free induction decay was calculated for each voxel enabling the reconstruction of locally resolved relaxation parameter maps. Results: The infarcted areas showed an increase in sodium density between 160% and 250%, while the T₂* relaxation time increased by 5%-72% compared to unaffected contralateral brain tissue. Conclusion: ²³Na chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm³ enabled sodium imaging of the anatomical small mouse brain and the acquired data allowed calculating relaxation parameter maps and hence a more exact evaluation of sodium signal changes after stroke. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]