Slew-rate dependence of tracer magnetization response in magnetic particle imaging.
Slew-rate dependence of tracer magnetization response in magnetic particle imaging.
复制标题
磁粒子成像中示踪剂磁化响应的转换速率依赖性。
DOI：
10.1063/1.4900605
复制
发表时间：
2014
影响因子：
3.2
通讯作者：
K. Krishnan
中科院分区：
文献类型：
--
作者：
Saqlain A. Shah;R. M. Ferguson;K. Krishnan
磁粒子成像(MPI)是一种新的生物医学成像技术，它可以产生实时、高分辨率的超顺磁性氧化铁纳米粒子示踪剂的断层图像。目前，25 khz和20 mT/μ0激励场在MPI中很常见，但在未来的设计中，出于患者安全的考虑，可能需要较低的场幅度。在这里，我们解决了有关MPI示踪剂磁化动力学的基本问题，并预测了未来采用激励场幅度(HO)和频率(ω)新组合的扫描仪的示踪剂性能。使用优化的单分散MPI示踪剂，我们研究了在15.5、26和40.2 kHz、场幅从7到52 mT/μ0的驱动场条件下，驱动场频率和幅度的几种组合对示踪剂响应的影响。对于流体和固定化纳米颗粒样品，我们确定磁性响应是由内尔反转主导的。此外，我们还观察到峰值转换速率(ωHO)决定了示踪剂的磁响应。较小的幅度提供了相应较小的视场，有时会导致较小的磁滞回线。改变驱动场条件，但保持峰值转换速率恒定，使示踪剂响应几乎相同。更高的峰值转换速率导致示踪剂响应中最大信号强度的降低和更大的矫顽力。我们的实验结果与基于Stoner-Wohlfarth模型的理论是一致的。
Magnetic Particle Imaging (MPI) is a new biomedical imaging technique that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide nanoparticle tracers. Currently, 25 kHz and 20 mT/μ0 excitation fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. Here, we address fundamental questions about MPI tracer magnetization dynamics and predict tracer performance in future scanners that employ new combinations of excitation field amplitude (Ho ) and frequency (ω). Using an optimized, monodisperse MPI tracer, we studied how several combinations of drive field frequencies and amplitudes affect the tracer's response, using Magnetic Particle Spectrometry and AC hysteresis, for drive field conditions at 15.5, 26, and 40.2 kHz, with field amplitudes ranging from 7 to 52 mT/μ0. For both fluid and immobilized nanoparticle samples, we determined that magnetic response was dominated by Néel reversal. Furthermore, we observed that the peak slew-rate (ωHo) determined the tracer magnetic response. Smaller amplitudes provided correspondingly smaller field of view, sometimes resulting in excitation of minor hysteresis loops. Changing the drive field conditions but keeping the peak slew-rate constant kept the tracer response almost the same. Higher peak slew-rates led to reduced maximum signal intensity and greater coercivity in the tracer response. Our experimental results were in reasonable agreement with Stoner-Wohlfarth model based theories.
影响因子：
3.8
作者：
Arami, Hamed;Ferguson, R. M.;Krishnan, Kannan M.
通讯作者：
Krishnan, Kannan M.
影响因子：
2.7
作者：
Ferguson RM;Minard KR;Krishnan KM
通讯作者：
Krishnan KM