Sensitivity of quantitative relaxometry and susceptibility mapping to microscopic iron distribution
Sensitivity of quantitative relaxometry and susceptibility mapping to microscopic iron distribution
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DOI：
10.1002/mrm.27946
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发表时间：
2019-08-18
影响因子：
3.3
通讯作者：
Hernando, Diego
中科院分区：
文献类型：
--
作者：
Colgan, Timothy J.;Knobloch, Gesine;Hernando, Diego
目的确定铁的微观空间分布对弛豫法和磁化率法估计铁浓度的影响。方法采用蒙特卡罗模拟和体外实验的方法，建立不同微观分布的铁。用完整的红细胞来测量铁，会产生铁的不均匀分布，而裂解红细胞则会产生均匀的铁分布。然后使用多回波自旋回波和破坏的梯度回波采集来估计松弛参数(R2和R2*)和磁化率。结果模拟表明，即使在相同的铁浓度和体积磁化率的情况下，R2和R2*的测量结果也取决于铁的空间分布。同样，体外实验表明，R2和R2*的测量依赖于铁的微观空间分布，而定量磁化率图(QSM)磁化率估计反映了铁的浓度对空间分布不敏感。结论铁含量的R2和R2*与铁的空间分布有关。基于QSM的铁浓度估计对铁的微观空间分布不敏感，潜在地提供了铁浓度的分布独立的测量方法。
Purpose Determine the impact of the microscopic spatial distribution of iron on relaxometry and susceptibility-based estimates of iron concentration. Methods Monte Carlo simulations and in vitro experiments of erythrocytes were used to create different microscopic distributions of iron. Measuring iron with intact erythrocyte cells created a heterogeneous distribution of iron, whereas lysing erythrocytes was used to create a homogeneous distribution of iron. Multi-echo spin echo and spoiled gradient echo acquisitions were then used to estimate relaxation parameters (R2 and R2*) and susceptibility. Results Simulations demonstrate that R2 and R2* measurements depend on the spatial distribution of iron even for the same iron concentration and volume susceptibility. Similarly, in vitro experiments demonstrate that R2 and R2* measurements depend on the microscopic spatial distribution of iron whereas the quantitative susceptibility mapping (QSM) susceptibility estimates reflect iron concentration without sensitivity to spatial distribution. Conclusions R2 and R2* for iron quantification depend on the spatial distribution or iron. QSM-based estimation of iron concentration is insensitive to the microscopic spatial distribution of iron, potentially providing a distribution independent measure of iron concentration.