Schwarcz Attila, Bogner Peter, Meric Philippe, Correze Jean-Loup, Berente Zoltan, Pál József, Gallyas Ferenc, Doczi Tamas, Gillet Brigitte, Beloeil Jean-Claude
Department of Neurosurgery, University of Pécs, Pécs, Hungary.
Magn Reson Med. 2004 Feb;51(2):278-85. doi: 10.1002/mrm.10702.
It is generally believed that the apparent diffusion coefficient (ADC) changes measured by diffusion-weighted imaging (DWI) in brain pathologies are related to alterations in the water compartments. The aim of this study was to elucidate the role of compartmentalization in DWI via biexponential analysis of the signal decay due to diffusion. DWI experiments were performed on mouse brain over an extended range of b-values (up to 10,000 mm(-2) s) under intact, global ischemic, and cold-injury conditions. DWI was additionally applied to centrifuged human erythrocyte samples with a negligible extracellular space. Biexponential signal decay was found to occur in the cortex of the intact mouse brain. During global ischemia, in addition to a drop in the ADC in both components, a shift from the volume fraction of the rapidly diffusing component to the slowly diffusing one was observed. In cold injury, the biexponential signal decay was still present despite the electron-microscopically validated disintegration of the membranes. The biexponential function was also applicable for fitting of the data obtained on erythrocyte samples. The results suggest that compartmentalization is not an essential feature of biexponential decay in diffusion experiments.
一般认为，扩散加权成像（DWI）测量的脑病变表观扩散系数（ADC）变化与水腔室的改变有关。本研究的目的是通过对扩散引起的信号衰减进行双指数分析来阐明分区化在DWI中的作用。在完整、全脑缺血和冷损伤条件下，对小鼠脑在扩展的b值范围（高达10,000 mm(-2) s）内进行DWI实验。此外，将DWI应用于细胞外空间可忽略不计的离心人红细胞样本。发现完整小鼠脑皮质中存在双指数信号衰减。在全脑缺血期间，除了两个成分的ADC下降外，还观察到从快速扩散成分的体积分数向缓慢扩散成分的转变。在冷损伤中，尽管通过电子显微镜证实膜已解体，但双指数信号衰减仍然存在。双指数函数也适用于拟合红细胞样本获得的数据。结果表明，分区化不是扩散实验中双指数衰减的必要特征。
