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 ( 1 H‐MRS) of the brain requires that the water proton signal be adjusted for relaxation and partial volume effects. While single voxel 1 H‐MRS studies have often included measurements of water proton T 1 , T 2 , and density based on additional 1 H‐MRS acquisitions (e.g., at multiple echo or repetition times), this approach is not practical for 1 H‐MRS imaging ( 1 H‐MRSI). In this report we demonstrate a method for using in situ measurements of water T 1 , T 2 , and density to calculate metabolite concentrations from 1 H‐MRSI data. The relaxation and density data are coregistered with the 1 H‐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.