Characterizing Healthy and Diseased White Matter Using Quantitative Magnetization Transfer and Multicomponent T2 Relaxometry: A Unified View via a Four-Pool Model
Characterizing Healthy and Diseased White Matter Using Quantitative Magnetization Transfer and Multicomponent T2 Relaxometry: A Unified View via a Four-Pool Model
复制标题
DOI：
10.1002/mrm.22131
复制
发表时间：
2009-12-01
影响因子：
3.3
通讯作者：
Pike, G. Bruce
中科院分区：
文献类型：
--
作者：
Levesque, Ives R.;Pike, G. Bruce
脑白质的核磁共振弛豫和磁化转移可以用一个四池模型来描述：两个是水质子(在单独的髓鞘和细胞内外隔室中)，两个是与生物膜的脂类和蛋白质相关的质子(髓鞘和非髓鞘半固体)。这个模型被用来深入了解多组分定量T-2弛豫测量和定量磁化转移成像的观察结果，这两个模型都基于简化的白质模型，并且在体内实验上是可行的。使用描述四池白质模型中磁化行为的一组耦合Bloch方程，对定量T-2弛豫测量和定量磁化转移成像技术进行了模拟。对四池模型进行了受病理学启发的修改，以评估它们对定量T-2弛豫测量和定量磁化转移成像观察的影响。我们的结果表明，水在显微解剖隔间的移动速率的变化可能会影响其他稳定的T-2弛豫定量观测；尽管存在两个不同的半固态成分，但基于磁化转移成像的半固态池数量的测量是稳健的；以及定量磁化转移成像隔室大小的估计不受细胞内/外水池的T-2变化的影响。四池模型虽然不适用于活体表征，但对于解释基于白质简化模型的定量MRI方法观察到的变化具有重要的洞察力。《医学评论》62：1487-1496,2009。(C)2009年Wiley-Liss，Inc.
Nuclear magnetic resonance relaxation and magnetization transfer in cerebral white matter can be described using a four-pool model: two for water protons (in separate myelin and intra/extracellular compartments) and two for protons associated with the lipids and proteins of biologic membranes (of myelin and nonmyelin semisolids). This model was used to gain insight into the observations from multicomponent quantitative T-2 relaxometry and quantitative magnetization transfer imaging, both based on simplified white matter models and experimentally feasible in vivo. Using a set of coupled Bloch equations describing the behavior of the magnetization in a four-pool model of white matter, simulations of the quantitative T-2 relaxometry and quantitative magnetization transfer imaging techniques were performed. pathology-inspired modifications were made to the four-pool model to gauge their impact on quantitative T-2 relaxometry and quantitative magnetization transfer imaging observations. Our results show that changes in the rate of water movement between microanatomic compartments may impact otherwise stable quantitative T-2 relaxometry observations; that the measure of the quantitative magnetization transfer imaging-based semisolid pool population is robust, despite the presence of two distinct semisolid components; and that quantitative magnetization transfer imaging compartment size estimates are not influenced by changes in the T-2 of the intra/extracellular water pool. The four-pool model, while impractical for in vivo characterization, yields important insight into the interpretation of changes observed with these quantitative MRI methods based on simplified models of white matter. Magn Reson Med 62:1487-1496, 2009. (C) 2009 Wiley-Liss, Inc.