Magnetic susceptibility anisotropy: cylindrical symmetry from macroscopically ordered anisotropic molecules and accuracy of MRI measurements using few orientations.
Magnetic susceptibility anisotropy: cylindrical symmetry from macroscopically ordered anisotropic molecules and accuracy of MRI measurements using few orientations.
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DOI：
10.1016/j.neuroimage.2012.12.050
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发表时间：
2013-04-15
期刊：
影响因子：
5.7
通讯作者：
Wang, Yi
中科院分区：
文献类型：
--
作者：
Wisnieff, Cynthia;Liu, Tian;Spincemaille, Pascal;Wang, Shuai;Zhou, Dong;Wang, Yi
关键词：
白质是中枢神经系统的重要组成部分，是多发性硬化症 (MS) 等神经退行性疾病的主要关注点。最近的 MRI 研究利用磁化率张量成像探索了白质独特的各向异性磁特性。然而，这些测量在实践中受到精确重建磁化率张量所需的大量不同头部方向的抑制。添加合理的约束可以减少模型参数的数量，并有助于从少量方向调节张量重建。宏观磁化率被分解为分子磁极化率之和，表明分子排列的宏观有序性对于磁化率各向异性的存在和对称性至关重要，而柱对称性是有序分子排列的自然结果。通过其条件数分析了磁化率张量重建中的噪声传播，表明张量重建对获取的主体方向的分布和张量对称性非常敏感，并且对相对于获取的方向不有利的纤维方向上的磁化率各向异性的严重高估或低估。研究发现，仔细采集三个非共面方向并使用扩散张量成像引导的圆柱对称可以合理估计人脑某些主要白质束的磁化率各向异性。
White matter is an essential component of the central nervous system and is of major concern in neurodegenerative diseases such as multiple sclerosis (MS). Recent MRI studies have explored the unique anisotropic magnetic properties of white matter using susceptibility tensor imaging. However, these measurements are inhibited in practice by the large number of different head orientations needed to accurately reconstruct the susceptibility tensor. Adding reasonable constraints reduces the number of model parameters and can help condition the tensor reconstruction from a small number of orientations. The macroscopic magnetic susceptibility is decomposed as a sum of molecular magnetic polarizabilities, demonstrating that macroscopic order in molecular arrangement is essential to the existence of and symmetry in susceptibility anisotropy and cylindrical symmetry is a natural outcome of an ordered molecular arrangement. Noise propagation in the susceptibility tensor reconstruction is analyzed through its condition number, showing that the tensor reconstruction is highly susceptible to the distribution of acquired subject orientations and to the tensor symmetry properties, with a substantial over- or under-estimation of susceptibility anisotropy in fiber directions not favorably oriented with respect to the acquired orientations. It was found that a careful acquisition of three non-coplanar orientations and the use of cylindrical symmetry guided by diffusion tensor imaging allowed reasonable estimation of magnetic susceptibility anisotropy in certain major white matter tracts in the human brain.
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DOI：
10.1073/pnas.0910222107
发表时间：
2010-03-16
影响因子：
11.1
作者：
Lee, Jongho;Shmueli, Karin;Duyn, Jeff H.
通讯作者：
Duyn, Jeff H.
影响因子：
10.6
作者：
Kressler B;de Rochefort L;Liu T;Spincemaille P;Jiang Q;Wang Y
通讯作者：
Wang Y
影响因子：
2.3
作者：
HROUDA, F;SCHULMANN, K
通讯作者：
SCHULMANN, K
影响因子：
2.9
作者：
Bender, B.;Klose, U.
通讯作者：
Klose, U.
影响因子：
5.7
作者：
Lee, Jongho;van Gelderen, Peter;Kuo, Li-Wei;Merkle, Hellmut;Silva, Afonso C.;Duyn, Jeff H.
通讯作者：
Duyn, Jeff H.