title: Magnetic resonance imaging-based compartmentation and its application to measuring metabolite concentrations in the frontal lobe.
abstract: Partial volume mixing of water compartments within a spectroscopy voxel (e.g. cerebrospinal fluid within a "brain" voxel) may, if not corrected for, lead to underestimation of brain metabolite concentrations. To correct for this source of bias, a new imaging-based method of compartmentation analysis is presented. Brain water, cerebrospinal fluid and solid matter content were obtained from proton density- and T2-weighted images of the brain and an 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 (betaMR) 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 betaMR determined by imaging, the T2-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-based compartmentation is a rapid and straightforward technique, and can be performed on standard MR systems.
authors.affiliation: Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, United Kingdom.
authors.forename: J C
authors.initials: JC
authors.lastname: Brooks
authors.forename: N
authors.initials: N
authors.lastname: Roberts
authors.forename: G J
authors.initials: GJ
authors.lastname: Kemp
authors.forename: P A
authors.initials: PA
authors.lastname: Martin
authors.forename: G H
authors.initials: GH
authors.lastname: Whitehouse
mesh_terms: D000328:Adult; D000465:Algorithms; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001834:Body Water / Q000737:chemistry; D002555:Cerebrospinal Fluid / Q000737:chemistry; D002794:Choline / Q000032:analysis; D003401:Creatine / Q000032:analysis; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007294:Inositol / Q000032:analysis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D012815:Signal Processing, Computer-Assisted
chemical_list: D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline