Quantitative t1ρ NMR spectroscopy of rat cerebral metabolites in vivo: Effects of global ischemia

✍ Scribed by Mikko I. Kettunen; Olli H.J. Gröhn; Risto A. Kauppinen

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 111 KB
• Volume: 51
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.20099

✦ Synopsis

Abstract

The NMR relaxation times (T~1ρ~, T~2~, and T~1~) of water, N‐acetylaspartate (NAA), creatine (Cr), choline‐containing compounds (Cho), and lactate (Lac) were quantified in rat brain at 4.7 T. In control animals, the cerebral T~1ρ~ figures, as determined with a spin‐lock field of 1.0 G, were 575 ± 30 ms, 380 ± 19 ms, 705 ± 53 ms, and 90 ± 1 ms for NAA, Cr, Cho, and water, respectively. The T~1ρ~ figures were 62–103% longer than their respective T~2~ values determined by a multiecho method. In global (ischemic) ischemia, T~1ρ~ of NAA declined by 34%, that of Cr and Cho did not change, and that of water increased by 10%. The T~1ρ~ of lactate in ischemic brain was 367 ± 44 ms. Similar patterns of changes were observed in the multiecho T~2~ of these cerebral metabolites. The T~1~ of water and NAA changed in a fashion similar to that of T~1ρ~ and T~2~. These results show differential responses in metabolite and water T~1ρ~ relaxation times following ischemia, and indicate that metabolite T~1ρ~ and T~2~ relaxation times behave similarly in the ischemic brain. The contributions of dipolar and nondipolar effects on T~1ρ~ relaxation in vivo are discussed in this work. Magn Reson Med 51:875–880, 2004. © 2004 Wiley‐Liss, Inc.