Magnetic resonance imaging-based compartmentation and its application to measuring metabolite concentrations in the frontal lobe

Partial volume mixing of water compartments within a spectroscopy voxel (e. g. cerebrospinal fluid within a "brain" voxel) may, if not corrected for, l ead to underestimation of brain metabolite concentrations, To correct for t his source of bias, a new imaging-based method of compartmentation analysis is presented. Brain water, cerebrospinal fluid and solid matter content we re obtained from proton density- and T-2-weighted images of the brain and a n external standard in 10 healthy young males (21 to 30 years), and results compared with a previously-described technique based on spectroscopy. Mean (SD) fractional water content (beta(MR)) Of the 2 x 2 x 2 cm3 voxel in the frontal lobes was 0.79 (0.03) by imaging, slightly but significantly (p = 0.03) smaller than the value of 0.83 (0.03) obtained by spectroscopy. From water-suppressed spectra recorded at five echo times, using beta(MR) determ ined by imaging, the T-2-corrected concentrations of compounds containing N -acetylaspartate, creatine, choline and myo-inositol were 10.6 (1.0), 8.0 ( 0.9), 1.6 (0.3) and 3.7 (0.7) mmol.l(-1) of brain, respectively. Imaging-ba sed compartmentation is a rapid and straightforward technique, and can be p erformed on standard MR systems. Magn Reson Med 41:883-888, 1999. (C) 1999 Wiley-Liss, Inc.