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Absolute quantitation of brain metabolites with respect to heterogeneous tissue compositions in H-1-MR spectroscopic volumes

Absolute quantitation of brain metabolites with respect to heterogeneous tissue compositions in H-1-MR spectroscopic volumes

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Authors

  • Alexander Gussew
  • Marko Erdtel
  • Patrick Hiepe
  • Reinhard Rzanny
  • Jurgen R. Reichenbach

Research units

Info

Original languageEnglish
Pages321-333
Number of pages13
JournalMagnetic Resonance Materials in Physics Biology and Medicine
Journal publication dateOct 2012
Volume25
Issue5
DOIs
StatePublished

Abstract

Referencing metabolite intensities to the tissue water intensity is commonly applied to determine metabolite concentrations from in vivo H-1-MRS brain data. However, since the water concentration and relaxation properties differ between grey matter, white matter and cerebrospinal fluid (CSF), the volume fractions of these compartments have to be considered in MRS voxels.

The impact of partial volume correction was validated by phantom measurements in voxels containing mixtures of solutions with different NAA and water concentrations as well as by analyzing in vivo H-1-MRS brain data acquired with various voxel compositions.

Phantom measurements indicated substantial underestimation of NAA concentrations when assuming homogeneously composed voxels, especially for voxels containing solution, which simulated CSF (error: a parts per thousand currency sign92%). This bias was substantially reduced by taking into account voxel composition (error: a parts per thousand currency sign10%). In the in vivo study, tissue correction reduced the overall variation of quantified metabolites by up to 35% and revealed the expected metabolic differences between various brain tissues.

Tissue composition affects extraction of metabolite concentrations and may cause misinterpretations when comparing measurements performed with different voxel sizes. This variation can be reduced by considering the different tissue types by means of combined analysis of spectroscopic and imaging data.

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