School of Physics, Trinity College Dublin, University of Dublin, Ireland.
Magn Reson Med. 2012 Mar;67(3):740-9. doi: 10.1002/mrm.23031. Epub 2011 Jun 15.
A technique for noninvasively quantifying the concentration of sodium ((23) Na) ions was applied to the study of ischemic stroke. (23) Na-magnetic resonance imaging techniques have shown considerable potential for measuring subtle changes in ischemic tissue, although studies to date have suffered primarily from poor signal/noise ratio. In this study, accurate quantification of tissue sodium concentration (TSC) was achieved in (23) Na images with voxel sizes of 1.2 μL acquired in 10 min. The evolution of TSC was investigated from 0.5 to 8 h in focal cortical and subcortical ischemic tissue following permanent middle cerebral artery occlusion in the rat (n = 5). Infarct volumes determined from TSC measurements correlated significantly with histology (P = 0.0006). A delayed linear model was fitted to the TSC time course data in each voxel, which revealed that the TSC increase was more immediate (0.2 ± 0.1 h delay time) in subcortical ischemic tissue, whereas it was delayed by 1.6 ± 0.5 h in ischemic cortex (P = 0.0002). No significant differences (P = 0.5) were measured between TSC slope rates in cortical (10.2 ± 1.1 mM/h) and subcortical (9.7 ± 1.1 mM/h) ischemic tissue. The data suggest that any TSC increase measured in ischemic tissue indicates infarction (core) and regions exhibiting a delay to TSC increase indicate potentially salvageable tissue (penumbra).
一种无创定量钠离子 ((23) Na) 浓度的技术被应用于缺血性中风的研究。(23) Na 磁共振成像技术在测量缺血组织的细微变化方面显示出了很大的潜力，尽管迄今为止的研究主要受到信噪比差的限制。在这项研究中，通过采集 10 分钟内的 1.2 μL 体素大小的 (23) Na 图像，实现了组织钠浓度 (TSC) 的精确定量。在大鼠永久性大脑中动脉闭塞后，研究了 0.5 至 8 小时内皮质和皮质下缺血组织的 TSC 演变（n = 5）。从 TSC 测量确定的梗塞体积与组织学显著相关（P = 0.0006）。对每个体素的 TSC 时间过程数据拟合了延迟线性模型，该模型揭示了 TSC 的增加在皮质下缺血组织中更为直接（0.2 ± 0.1 h 延迟时间），而在缺血皮质中则延迟了 1.6 ± 0.5 h（P = 0.0002）。在皮质（10.2 ± 1.1 mM/h）和皮质下（9.7 ± 1.1 mM/h）缺血组织中，TSC 斜率率之间没有测量到显著差异（P = 0.5）。数据表明，在缺血组织中测量到的任何 TSC 增加都表明梗塞（核心），而表现出 TSC 增加延迟的区域则表明可能有挽救的组织（半影）。
