Generalized Lorentzian Tensor Approach (GLTA) as a biophysical background for quantitative susceptibility mapping.
Generalized Lorentzian Tensor Approach (GLTA) as a biophysical background for quantitative susceptibility mapping.
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DOI：
10.1002/mrm.25538
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发表时间：
2015-02
影响因子：
3.3
通讯作者：
Sukstanskii, Alexander L.
中科院分区：
文献类型：
--
作者：
Yablonskiy, Dmitriy A.;Sukstanskii, Alexander L.
关键词：
定量磁化率成像（QSM）是一种潜在的强大的梯度回忆回波（GRE） MRI组织磁化率成像技术。本文的目的是在细胞水平上推导出GRE信号相位与潜在组织微观结构和磁化率之间的关系。我们利用麦克斯韦方程组和统计方法推导了分布在细胞内外空间的细胞成分（蛋白质、脂质、铁等）诱导的不均匀磁场在单室和多室系统中磁化率诱导的MR信号频移的表达式。我们介绍了广义洛伦兹张量方法（GLTA），它可以解释两种类型的各向异性：磁化率的各向异性和结构组织的各向异性。在GLTA中，由于局部环境引起的频移由洛伦兹张量L³表征，其结构与磁化率张量χ³有很大不同。χ n的分量只是相对体积对区室敏感性的加权，而L n的分量是由特定的数值因子加权的，这取决于组织的微对称性和与MR脉冲序列相关的参数。我们还提供了连接现象学和微观考虑的方程。GLTA为破译相位数据提供了一致的背景。
Quantitative susceptibility mapping (QSM) is a potentially powerful technique for mapping tissue magnetic susceptibility from gradient recalled echo (GRE) MRI. Herein we aim to derive the relationships between GRE signal phase and the underlying tissue microstructure and magnetic susceptibility at the cellular level. We use Maxwell’s equations and a statistical approach to derive the expression for the magnetic-susceptibility-induced MR signal frequency shift of the GRE signal in single- and multi-compartment systems, in which inhomogeneous magnetic field is induced by the cellular constituents (proteins, lipids, iron, etc.) distributed in intra- and extra-cellular spaces. We introduce the Generalized Lorentzian Tensor Approach (GLTA) that accounts for both types of anisotropy: the anisotropy of magnetic susceptibility and the structural tissue anisotropy. In the GLTA the frequency shift due to the local environment is characterized by the Lorentzian tensor L̂ which has a substantially different structure than the susceptibility tensor χ̂. While components of χ̂ are simply compartmental susceptibilities “weighted” by their relative volumes, the components of L̂ are weighted by specific numerical factors depending on tissue micro-symmetry and parameters related to the MR pulse sequence. We also provide equations bridging phenomenological and microscopic considerations. The GLTA provides a consistent background for deciphering phase data.
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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