定量弛豫率和磁化率映射对微观铁分布的敏感性。
Sensitivity of quantitative relaxometry and susceptibility mapping to microscopic iron distribution.
机构信息
Department of Radiology, University of Wisconsin, Madison, Wisconsin.
Department of Medical Physics, University of Wisconsin, Madison, Wisconsin.
出版信息
Magn Reson Med. 2020 Feb;83(2):673-680. doi: 10.1002/mrm.27946. Epub 2019 Aug 18.
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 ( and ) and susceptibility.
RESULTS
Simulations demonstrate that and measurements depend on the spatial distribution of iron even for the same iron concentration and volume susceptibility. Similarly, in vitro experiments demonstrate that and 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
and 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.
目的
确定铁的微观空间分布对弛豫率和基于磁化率的铁浓度估计的影响。
方法
使用蒙特卡罗模拟和红细胞的体外实验来创建不同的铁微观分布。用完整的红细胞测量铁会产生铁的不均匀分布，而溶红细胞则用于产生铁的均匀分布。然后使用多回波自旋回波和扰相梯度回波采集来估计弛豫参数（T1 和 T2）和磁化率。
结果
模拟表明，即使对于相同的铁浓度和体积磁化率，T1 和 T2 的测量也取决于铁的空间分布。同样，体外实验表明，T1 和 T2 的测量取决于铁的微观空间分布，而定量磁化率映射（QSM）磁化率估计则反映了铁浓度，而不受空间分布的影响。
结论
用于铁定量的 T1 和 T2 取决于铁的空间分布。基于 QSM 的铁浓度估计对铁的微观空间分布不敏感，可能提供一种对铁浓度的分布无关的测量。
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