Toward absolute quantification of iron oxide nanoparticles as well as cell internalized fraction using multiparametric MRI.
Toward absolute quantification of iron oxide nanoparticles as well as cell internalized fraction using multiparametric MRI.
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DOI：
10.1002/cmmi.1467
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发表时间：
2012-07
影响因子：
--
通讯作者：
Mattrey, R. F.
中科院分区：
文献类型：
--
作者：
Girard, O. M.;Ramirez, R.;McCarty, S.;Mattrey, R. F.
关键词：
氧化铁纳米粒子（IONP）由于其强磁性和广泛的应用而被广泛用作MR造影剂。由IONP引起的对比度通常取决于浓度、水可及性、颗粒大小和IONP在微环境内分布的异质性。虽然后者可能是在分子水平上评估局部生理效应的工具，但它使来自弛豫测量的IONP定量具有挑战性。本研究旨在使用敏感性测量来量化IONP浓度。此外，松弛数据的进一步分析，提出了提取定量信息的IONP的空间分布。用IONP标记间充质干细胞，并通过质谱法测量IONP浓度。MR弛豫参数（T1，T2，T2*），以及磁化率的圆柱形样品含有系列稀释液的混合物的自由和细胞内化的IONP进行了测量，并与IONP浓度。与弛豫数据不同，磁化率与IONP是否游离或内化无关，使其成为IONP定量的绝佳候选者。使用来自质谱的IONP浓度和测量的弛豫时间，准确计算游离和内化的IONP分数。在这项初步研究中，磁化率被证明是一种可靠的测量IONP浓度的技术。新型成像为基础的磁化率映射技术可以证明是有价值的工具，定量IONP浓度直接通过MRI，为任意形状的样品。结合弛豫时间映射技术，特别是T2和T2*，这可能是一种有效的方式来测量IONP浓度和内化的IONP分数在体内使用MRI，以获得洞察组织功能和分子成像范例。
Iron oxide nanoparticles (IONPs) are widely used as MR contrast agents because of their strong magnetic properties and broad range of applications. The contrast induced by IONPs typically depends on concentration, water accessibility, particle size, and heterogeneity of IONP distribution within the microenvironment. Although the latter could be a tool to assess local physiological effects at the molecular level, it renders IONP quantification from relaxation measurements challenging. This study aims to quantify IONP concentration using susceptibility measurements. In addition, further analysis of relaxation data is proposed to extract quantitative information about the IONP spatial distribution. Mesenchymal stem cells were labeled with IONPs and the IONP concentration measured by mass spectroscopy. MR relaxation parameters (T1, T2, T2*) as well as magnetic susceptibility of cylindrical samples containing serial dilutions of mixtures of free and cell-internalized IONPs were measured and correlated with IONP concentration. Unlike relaxation data, magnetic susceptibility was independent of whether IONPs were free or internalized, making it an excellent candidate for IONP quantification. Using IONP concentration derived from mass spectroscopy and measured relaxation times, free and internalized IONP fractions were accurately calculated. Magnetic susceptibility was shown to be a robust technique to measure IONP concentration in this preliminary study. Novel imaging based susceptibility mapping techniques could prove to be valuable tools to quantify IONP concentration directly by MRI, for samples of arbitrarily shape. Combined with relaxation time mapping techniques, especially T2 and T2*, this could be an efficient way to measure both IONP concentration and the internalized IONP fraction in vivo using MRI, to gain insight into tissue function and molecular imaging paradigms.
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