title: Measuring T2 in vivo with J-difference editing: application to GABA at 3 Tesla.
abstract: OBJECTIVE
  To develop an experimental approach for determining in vivo transverse relaxation rates (T(2)) of metabolites that are detected by spectral editing without using simulations, and to demonstrate this approach to measure the T(2) of γ-aminobutyric acid (GABA).
  
  
  METHODS
  The proposed method first determines the TE-dependence of the edited signals using measurements in a pure phantom solution (10 mM γ-aminobutyric acid; GABA); the phantom T(2) is also determined. Once the editing echo time (TE)-modulation pattern is known, it can then be used to determine T(2) in vivo. The method was applied to measure GABA T(2) in the occipital lobe of five healthy adult subjects at 3T, using a J-difference editing method. Unwanted macromolecular contributions to the GABA signal were also measured.
  
  
  RESULTS
  The in vivo T(2) of edited GABA signal was 88 ± 12 ms; this preliminary result is somewhat shorter than other metabolite T(2) values in the literature at this field strength.
  
  
  CONCLUSIONS
  Spectral editing methods are now widely used to detect low concentration metabolites, such as GABA, but to date no edited acquisition methods have been proposed for the measurement of transverse relaxation times (T(2)). The method described has been successfully applied to measuring the T(2) of GABA.
authors: Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. raee2@jhu.edu
authors: Richard A E
authors: RA
authors: Edden
authors: Jarunee
authors: J
authors: Intrapiromkul
authors: He
authors: H
authors: Zhu
authors: Ying
authors: Y
authors: Cheng
authors: Peter B
authors: PB
authors: Barker
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology; D001923:Brain Chemistry; D001931:Brain Mapping / Q000379:methods; D003198:Computer Simulation; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011522:Protons; D015203:Reproducibility of Results; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D011522:Protons; D005680:gamma-Aminobutyric Acid