Ozarslan Evren, Basser Peter J, Shepherd Timothy M, Thelwall Peter E, Vemuri Baba C, Blackband Stephen J
STBB/LIMB/NICHD, National Institutes of Health, Bethesda, MD 20892, USA.
J Magn Reson. 2006 Dec;183(2):315-23. doi: 10.1016/j.jmr.2006.08.009. Epub 2006 Sep 8.
This report introduces a novel method to characterize the diffusion-time dependence of the diffusion-weighted magnetic resonance (MR) signal in biological tissues. The approach utilizes the theory of diffusion in disordered media where two parameters, the random walk dimension and the spectral dimension, describe the evolution of the average propagators obtained from q-space MR experiments. These parameters were estimated, using several schemes, on diffusion MR spectroscopy data obtained from human red blood cell ghosts and nervous tissue autopsy samples. The experiments demonstrated that water diffusion in human tissue is anomalous, where the mean-square displacements vary slower than linearly with diffusion time. These observations are consistent with a fractal microstructure for human tissues. Differences observed between healthy human nervous tissue and glioblastoma samples suggest that the proposed methodology may provide a novel, clinically useful form of diffusion MR contrast.
本报告介绍了一种表征生物组织中扩散加权磁共振（MR）信号的扩散时间依赖性的新方法。该方法利用无序介质中的扩散理论，其中两个参数，即随机游走维度和谱维度，描述了从q空间MR实验获得的平均传播子的演化。使用几种方案对从人类红细胞幽灵和神经组织尸检样本获得的扩散MR光谱数据估计了这些参数。实验表明，人体组织中的水扩散是异常的，其中均方位移随扩散时间的变化比线性变化慢。这些观察结果与人体组织的分形微观结构一致。在健康人类神经组织和胶质母细胞瘤样本之间观察到的差异表明，所提出的方法可能提供一种新的、临床上有用的扩散MR对比形式。
