Metabolite proton T(2) mapping in the healthy rhesus macaque brain at 3 T

Magn Reson Med. 2009 Nov;62(5):1292-9. doi: 10.1002/mrm.22117.

Abstract

The structure and metabolism of the rhesus macaque brain, an advanced model for neurologic diseases and their treatment response, is often studied noninvasively with MRI and (1)H-MR spectroscopy. Due to the shorter transverse relaxation time (T(2)) at the higher magnetic fields these studies favor, the echo times used in (1)H-MR spectroscopy subject the metabolites to unknown T(2) weighting, decreasing the accuracy of quantification which is key for inter- and intra-animal comparisons. To establish the "baseline" (healthy animal) T(2) values, we mapped them for the three main metabolites' T(2)s at 3 T in four healthy rhesus macaques and tested the hypotheses that their mean values are similar (i) among animals; and (ii) to analogs regions in the human brain. This was done with three-dimensional multivoxel (1)H-MR spectroscopy at (0.6 x 0.6 x 0.5 cm)(3) = 180 microL spatial resolution over a 4.2 x 3.0 x 2.0 = 25 cm(3) ( approximately 30%) of the macaque brain in a two-point protocol that optimizes T(2) precision per unit time. The estimated T(2)s in several gray and white matter regions are all within 10% of those reported in the human brain (mean +/- standard error of the mean): N-acetylaspartate = 316 +/- 7, creatine = 177 +/- 3, and choline = 264 +/- 9 ms, with no statistically significant gray versus white matter differences.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aspartic Acid / analogs & derivatives*
  • Aspartic Acid / metabolism
  • Brain / metabolism*
  • Choline / metabolism*
  • Female
  • Macaca mulatta
  • Magnetic Resonance Imaging / methods*
  • Magnetic Resonance Spectroscopy / methods*
  • Protons
  • Tissue Distribution

Substances

  • Protons
  • Aspartic Acid
  • N-acetylaspartate
  • Choline