High resolution localized two-dimensional MR spectroscopy in mouse brain in vivo.

Localized two-dimensional MR spectroscopy (2D MRS) is impacting the in vivo studies of brain metabolites due to improved spectral resolution and unambiguous assignment opportunities. Despite the large number of transgenic mouse models available for neurological disorders, localized 2D MRS has not yet been implemented in the mouse brain due to size constraints. In this study we optimized a localized 2D proton chemical shift correlated spectroscopic sequence at field strength of 9.4T to obtain highly resolved 2D spectra from localized regions in mouse brains in vivo. The combination of the optimized 2D sequence, high field strength, strong gradient system, efficient water suppression, and the use of a short echo time allowed clear detection of cross-peaks of up to 16 brain metabolites, allowing their direct chemical shift assignments in vivo. To our knowledge this is the first in vivo 2D MRS study of the mouse brain, demonstrating its feasibility to resolve and simultaneously assign several metabolite resonances in the mouse brain in vivo. Implementation of 2D MRS will be invaluable in the identification of new biomarkers during disease progression and treatment using the various available mouse models.