Dynamic Inverse Problems in Magnetic Particle Imaging (D-MPI)

磁粒子成像中的动态反问题 (D-MPI)

• 批准号: 426078691
• 负责人: Professorin Dr. Bernadette Hahn-Rigaud
• 金额: --
• 依托单位: Zentrum für Technomathematik (ZeTeM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/426078691?language=en
• 关键词: Dynamic; Inverse; Problems; Magnetic; Particle

Magnetic particle imaging (MPI) is an imaging modality with promising medical applications that relies on the behavior of superparamagnetic iron oxide nanoparticles. The particles' nonlinear response to a highly dynamic applied magnetic field induces a voltage measured in multiple receive coils from which an image showing the spatially dependent concentration of the nanoparticles can be reconstructed. A high temporal and a potentially high spatial resolution make MPI suitable for several in vivo applications without any associated harmful radiation.MPI is currently in the preclinical phase. However, several crucial dynamic aspects have been left out of consideration so far to simplify modeling, data acquisition and reconstruction. In this collaborative project, we address three dynamic aspects of MPI resulting in a variety of dynamic inverse problems: (i) concentration dynamics, (ii) magnetic field dynamics, and (iii) particle magnetization dynamics.Experimental results indicate that temporal changes of the concentration (i) are highly relevant during the reconstruction due to an interplay of environmental dynamic processes (like the heart beat) and the necessary repetition of sequential measurements to obtain sufficient signal quality. Thus, we aim for developing reconstruction methods which take the dynamic behavior of the concentration explicitly into account in order to significantly improve the reconstruction results in applications like, for example, flow estimation or instrument tracking.Safety regulations limit the amplitudes of the dynamic part of the applied magnetic field which results in a limited field-of-view (FOV) during one measurement cycle.Increasing the FOV and developing dynamic measurement strategies encoded in the applied magnetic field (ii) is of major interest for current animal-size and particularly for future human-size applications. In this project, we intend to develop a strategy to reduce the calibration costs, adaptive sampling schemes to capture the desired features efficiently and respective dynamic reconstruction algorithms.We further address the still unsolved problem of modeling the system function in MPI properly. It is related to the particles' magnetization behavior (iii) in the rapidly changing applied magnetic field. The behavior is mainly determined by Néel rotation mechanisms of large ensembles of nanoparticles. We propose to solve dynamic parameter identification problems in extended models for large ensembles of particles to enable model-based reconstruction in MPI.The solution of the different but interrelated dynamic problems addressed in this project are highly relevant for further developments of the MPI methodology enabling an entry into the clinical phase.

磁性粒子成像（MPI）是一种具有很好医学应用前景的成像方式，其依赖于超顺磁性氧化铁纳米颗粒的行为。颗粒对高度动态的施加磁场的非线性响应感应出在多个接收线圈中测量的电压，从该电压可以重建示出纳米颗粒的空间依赖性浓度的图像。高时间分辨率和潜在的高空间分辨率使MPI适合于多种体内应用，而没有任何相关的有害辐射。然而，到目前为止，为了简化建模、数据采集和重建，已经忽略了几个关键的动态方面。在这个合作项目中，我们解决了MPI的三个动态方面，从而产生了各种动态逆问题：（i）浓度动力学，（ii）磁场动力学，和（iii）粒子磁化动力学。实验结果表明，由于环境动态过程的相互作用，浓度（i）的时间变化在重建过程中具有高度相关性（如心跳）和必要的重复顺序测量以获得足够的信号质量。因此，我们的目标是开发明确考虑浓度的动态行为的重建方法，以显着改善应用中的重建结果，例如，安全法规限制了所施加磁场的动态部分的幅度，这导致有限的视场（FOV）增加FOV和开发在所施加的磁场中编码的动态测量策略（ii）对于当前的动物大小并且特别是对于未来的人类大小的应用是主要感兴趣的。在这个项目中，我们打算开发一种策略，以减少校准成本，自适应采样方案，以有效地捕捉所需的功能和相应的动态重建算法。我们进一步解决仍然没有解决的问题，在MPI中正确的建模系统功能。它与粒子在快速变化的外加磁场中的磁化行为有关。该行为主要由纳米粒子大集合的Néel旋转机制决定。我们建议解决动态参数识别问题，在扩展模型的大合奏的颗粒，使基于模型的重建在MPI。解决不同的，但相互关联的动态问题，在这个项目中解决的MPI方法的进一步发展，使进入临床阶段是高度相关的。