Water diffusion heterogeneity index in the human brain is insensitive to the orientation of applied magnetic field gradients
Water diffusion heterogeneity index in the human brain is insensitive to the orientation of applied magnetic field gradients
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DOI：
10.1002/mrm.20960
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发表时间：
2006-08-01
影响因子：
3.3
通讯作者：
Schmainda, Kathleen M.
中科院分区：
文献类型：
--
作者：
Bennett, Kevin M.;Hyde, James S.;Schmainda, Kathleen M.
利用磁共振成像（MRI），建立了弥散加权成像（DWI）方法，用于研究人脑中的非均匀水扩散。该模型的优点在于，它不需要关于表观扩散速率的体素内分布的形状的假设，并且它与该分布具有可计算的关系。α-DWI技术可用于检测与脑肿瘤侵袭相关的微结构组织变化，并可用于指导对侵袭肿瘤细胞的治疗。在先前的工作中，为了避免人为地将不均匀性源引入衰减，在沿沿着单个方向施加磁场梯度的情况下进行a-DWI。然而，已知受限扩散在大脑中是各向异性的，并且a-DWI方法必须考虑到这一点才是完整的。在这项工作中，在人脑中研究了所施加的磁场梯度和拟合的拉伸指数模型参数之间的关系。结果表明，扩散系数随梯度方向的变化而变化，而非均匀性指数a对梯度方向相对不敏感。建议在临床使用中，可以使用在单个方向上应用的反映组织异质性的扩散加权梯度来创建a的标测图。
The a diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The alpha-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, a-DWI was performed with magnetic field gradients applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the a-DWI method must take this into account to be complete. In this work the relationship between the applied magnetic field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of applied gradients, while the heterogeneity index a is relatively direction-insensitive. It is proposed that in clinical use, maps of a can be created using diffusion-weighting gradients applied in a single direction that reflect the tissue heterogeneity.