Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32608, United States of America.
Phys Med Biol. 2018 Sep 6;63(17):175016. doi: 10.1088/1361-6560/aad97d.
This paper presents the design, construction, and testing of a magnetic particle relaxometer (MPR) to assess magnetic nanoparticle response to dynamic magnetic fields while subjected to a bias field. The designed MPR can characterize magnetic particles for use as tracers in magnetic particle imaging (MPI), with the variation of an applied bias field emulating the scan of the MPI field free point. The system applies a high-frequency time-varying excitation field (up to 45 mT at 30 kHz), while slowly ramping a bias field (±100 mT in 1 s). The time-resolved response of the sample is measured using an inductive sensing coil system, made of a pick-up coil and a rotating and translating balancing coil to finely cancel the induction feed-through from the excitation field. A post-processing algorithm is presented to extract the tracer response related to the point spread function for MPI applications, and the performance of the MPR is demonstrated using superparamagnetic iron oxide particles (ferucarbotran).
本文介绍了一种磁粒子弛豫计（MPR）的设计、构建和测试，用于评估磁性纳米粒子在施加偏置场时对动态磁场的响应。设计的 MPR 可用于表征作为磁性粒子成像（MPI）示踪剂的磁性粒子，施加偏置场的变化模拟 MPI 无场点的扫描。该系统施加高频时变激励场（在 30 kHz 时高达 45 mT），同时缓慢斜坡偏置场（在 1 s 内±100 mT）。使用感应传感线圈系统测量样品的时间分辨响应，该系统由一个拾波线圈和一个旋转和平移的平衡线圈组成，以精细地抵消激励场的感应馈通。本文提出了一种后处理算法，用于提取与 MPI 应用相关的点扩散函数的示踪剂响应，并用超顺磁性氧化铁颗粒（ferucarbotran）演示了 MPR 的性能。
