A simplified method to measure the diffusion tensor from seven MR images
A simplified method to measure the diffusion tensor from seven MR images
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DOI：
10.1002/mrm.1910390610
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发表时间：
1998-06-01
影响因子：
3.3
通讯作者：
Pierpaoli, C
中科院分区：
文献类型：
--
作者：
Basser, PJ;Pierpaoli, C
水的扩散张量(D)在bar下的解析表达式，以及由此导出的标量不变量的解析表达式，给出了七个扩散加权图像（dwi）的强度。这些公式简化了扩散张量成像所需的后处理步骤，包括估计每个体素（从b矩阵集合及其相应的dwi）的bar下的(D)，然后计算其特征值、特征向量和标量不变量。在一项使用具有高扩散权重（b（max）类似于900 s/mm(2)）的无伪影dwi进行的研究中，通过分析和多元线性回归计算的痕量（(D)）图以及相对和晶格各向异性指数在健康活猫脑组织中显示出极好的一致性。然而，随着扩散权重的降低，解析计算地图的质量明显下降。尽管具有7个dwi的弥散张量MRI可能对需要快速扫描和数据处理的临床应用有用，但它不能提供测量成像参数的不确定性估计，使其容易受到噪声和系统伪影的影响。因此，在放射学应用中使用该技术时应小心。
Analytical expressions of the diffusion tensor of water, (D) under bar, and of scalar invariants derived from it, are given in terms of the intensities of seven diffusion-weighted images (DWIs). These formulas simplify the post-processing steps required in diffusion tensor imaging, including estimating (D) under bar in each voxel (from the set of b-matrices and their corresponding DWIs), and then computing its eigenvalues, eigenvectors, and scalar invariants. In a study conducted using artifact-free DWIs with high diffusion weighting (b(max) similar to 900 s/mm(2)), maps of Trace((D) under bar) and the Relative and Lattice Anisotropy indices calculated analytically and by multivariate linear regression showed excellent agreement in brain parenchyma of a healthy living cat. However, the quality of the analytically computed maps degraded markedly as diffusion weighting was reduced. Although diffusion tensor MRI with seven DWIs may be useful for clinical applications where rapid scanning and data processing are required, it does not provide estimates of the uncertainty of the measured imaging parameters, rendering it susceptible to noise and systematic artifacts. Therefore, care should be taken when using this technique in radiological applications.