Metabolite proton T2 mapping in the healthy rhesus macaque brain at 3 T

✍ Scribed by Songtao Liu; Oded Gonen; Roman Fleysher; Lazar Fleysher; James S. Babb; Brian J. Soher; Chan-Gyu Joo; Eva-Maria Ratai; R. Gilberto González

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 674 KB
• Volume: 62
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.22117

✦ Synopsis

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 × 0.6 × 0.5 cm)^3^ = 180 μL spatial resolution over a 4.2 × 3.0 × 2.0 = 25 cm^3^ (∼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. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.