Plane-wise sensitivity based inhomogeneous excitation fields for magnetorelaxometry imaging of magnetic nanoparticles
Plane-wise sensitivity based inhomogeneous excitation fields for magnetorelaxometry imaging of magnetic nanoparticles
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DOI：
10.1016/j.jmmm.2014.09.007
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发表时间：
2015-04-15
影响因子：
2.7
通讯作者：
Haueisen, Jens
中科院分区：
文献类型：
--
作者：
Baumgarten, Daniel;Braune, Friedemann;Haueisen, Jens
有前途的生物医学应用的磁性纳米粒子共享需要一个定量的知识，其在体内的分布。从多通道磁弛豫测量与顺序激活的非均匀激发场，分布可以定量确定。在第一项研究中，连续激活单激励线圈。我们的目标是通过涉及多个激励线圈的合适的激活模式来进一步推进这种成像技术。在这项工作中，我们提出了这些模式的空间灵敏度的基础上，以减少所需的测量的数量的估计。携带磁性纳米颗粒的体素的灵敏度由其相对于传感器的位置和保持的激励来确定。尽管位置在给定设置内是固定的，但激励由线圈中的电流控制。通过求解逆问题来估计所定义的目标灵敏度所需的电流。在我们的工作中，提出了两种目标灵敏度范例：（a）平面式激活，其中仅寻找具有高灵敏度的一个平面并将其移动通过源空间;以及（6）平面式非激活，其中除了一个平面之外的所有体素都应该接收高灵敏度。我们的方法进行了研究，在模拟研究中使用的设置与立方体感兴趣的区域和平面传感器阵列。评价两种激活范例的成像质量。我们的研究结果表明，这种基于空间灵敏度的方法定义非均匀激活模式的主要适用性。所获得的图案允许使用与常规单线圈激活相比更少数量的激活序列来实现类似的成像质量。(C)2014爱思唯尔有限公司版权所有。
Promising biomedical applications of magnetic nanoparticles share the need for a quantitative knowledge of their in vivo distribution. From multichannel magnetorelaxometry measurements with sequential activation of inhomogeneous excitation fields, the distribution can be quantitatively determined. In first studies, single excitation coils were consecutively activated. We aim at further advancing this imaging technology by suitable activation patterns involving multiple excitation coils. In this work, we propose the estimation of these patterns based on the spatial sensitivity in order to reduce the number of required measurements. The sensitivity of a voxel carrying magnetic nanoparticles is determined by its position relative to the sensors and the excitation held. Whereas the position is fixed within a given setup, the excitation is controlled by the currents in the coils. The currents required for a defined target sensitivity are estimated by solving an inverse problem. In our work, two target sensitivity paradigms are presented: (a) plane-wise activation, where only one plane with high sensitivities is sought and moved through the source space and (6) plane-wise non-activation, where all voxels except for one plane should receive high sensitivity. Our approach is investigated in simulation studies using a setup with a cubic region of interest and a planar sensor array. The imaging quality of both activation paradigms is evaluated. Our results demonstrate the principal applicability of this spatial sensitivity based approach for defining inhomogeneous activation patterns. The obtained patterns allow for a similar imaging quality using a lower number of activation sequences compared to the conventional single coil activation. (C) 2014 Elsevier B.V. All rights reserved.