Quantitative spectroscopic imaging with in situ measurements of tissue water T 1 , T 2 , and density

The use of tissue water as a concentration standard in proton magnetic resonance spectroscopy (1H-MRS) of the brain requires that the water proton signal be adjusted for relaxation and partial volume effects. While single voxel 1H-MRS studies have often included measurements of water proton T1, T2, and density based on additional 1H-MRS acquisitions (e.g., at multiple echo or repetition times), this approach is not practical for 1H-MRS imaging (1H-MRSI). In this report we demonstrate a method for using in situ measurements of water T1, T2, and density to calculate metabolite concentrations from 1H-MRSI data. The relaxation and density data are coregistered with the 1H-MRSI data and provide detailed information on the water signal appropriate to the individual subject and tissue region. We present data from both healthy subjects and a subject with brain lesions, underscoring the importance of water parameter measurements on a subject-by-subject and voxel-by-voxel basis. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.