Quantitative imaging of magnetic nanoparticles by magnetorelaxometry with multiple excitation coils
Quantitative imaging of magnetic nanoparticles by magnetorelaxometry with multiple excitation coils
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DOI：
10.1088/0031-9155/59/21/6607
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发表时间：
2014-11-07
影响因子：
3.5
通讯作者：
Trahms, L.
中科院分区：
文献类型：
--
作者：
Liebl, M.;Steinhoff, U.;Trahms, L.
基于磁性纳米粒子（MNP）的癌症新疗法需要对体内的MNP进行定量空间分辨成像。在磁弛豫法（MRX）中，纳米颗粒的分布可以通过在去除外部磁化场之后测量其弛豫来非侵入性地量化。通常，在MRX中，样品暴露于均匀磁化场，导致具有相当差的空间分辨率的定量重建。理论工作表明，空间分辨率的提高可以通过连续应用非均匀场磁化样品的一部分来实现。在这里，我们通过重建由54个石膏立方体（1 cm（3）cube（-1））制成的紧凑三维体积体模内的纳米颗粒分布，实验证明了这种方法的可行性，其中12个石膏立方体填充有MNP。使用围绕体模的48个小激励线圈，获得MRX信号序列，其中仅单个线圈附近的那些MNP有贡献。通过这48个MRX测量的组合评估，12个MNP填充的立方体的位置和含量可以被准确地确定，偏差小于4%，而通过常规均匀MRX，只有MNP含量是可重建的，偏差约为9%。结果表明，通过使用多个磁化场的顺序激活，定量MRX成像的改善。
New therapies against cancer based on magnetic nanoparticles (MNPs) require a quantitative spatially resolved imaging of MNPs inside a body. In magnetorelaxometry (MRX), a distribution of nanoparticles can be quantified non-invasively by measuring its relaxation after removal of an external magnetizing field. Conventionally, in MRX the sample is exposed to a homogeneous magnetizing field resulting in a quantitative reconstruction with rather poor spatial resolution. Theoretical work suggests an improvement of spatial resolution may be achieved by a sequential application of inhomogeneous fields magnetizing only parts of a sample. Here, we experimentally demonstrate the feasibility of this approach by reconstructing a nanoparticle distribution inside a compact three-dimensional volume phantom made of 54 gypsum cubes (1 cm(3) cube(-1)), of which 12 gypsum cubes were filled with MNPs. Using 48 small excitation coils surrounding the phantom, a sequence of MRX signals was obtained where only those MNPs near an individual coil contribute. By combined evaluation of these 48 MRX measurements, the positions and content of the 12 MNP-filled cubes could be determined accurately with a deviation below 4%, while by conventional homogeneous MRX only the MNP content was reconstructable with a deviation of about 9%. The results demonstrate the improvement of quantitative MRX imaging by using sequential activation of multiple magnetizing fields.