Establishment of quantitative Magnetic Particle Imaging (MPI) application oriented phantoms for preclinical investigations

在最近的一次呼吁中，DFG资助了磁粒子成像(MPI)扫描仪，以便为研究人员提供探索这种成像方法潜力的机会。这需要澄清新型成像方式的基本原理，例如MPI扫描仪的检测极限和图像分辨率。由于MPI示踪剂的特定局部配置，例如在血管系统或在肿瘤中，在特定的医疗应用中会出现进一步的特殊问题。该项目旨在建立计量基础设施以实现受控和验证的实验条件，这将作为定量MPI的良好基础。为此，应开发和提供专用模体，通过该模体可以对MPI扫描仪的个体成像特性进行计量监测。特别是，将解决现实医疗环境中示踪剂数量和分布的分辨率以及量化问题。此外，应调查MRT-MPI联合配准时解剖学和示踪剂分布的一致性。除了MRT，我们还将使用磁弛豫法作为独立的空间分辨率参考技术来评估MPI结果。为了真实地检查MPI扫描仪的性能，模体必须以受控的方式反映预期的医用MPI应用的基本属性。这包括MPI示踪剂的浓度变化、流动性和粘度，以及生理介质(血液)的速度、温度、粘度和直径。通过这种方法，体内MPI测量的有效性将增加，临床前研究的设计将建立在可靠、合理的基础上，增加这些项目的成功前景。因此，动物试验的次数可以减少。由此产生的长期稳定的模体将提供给与DFG资助的两个MPI扫描仪站点合作的医生和物理学家，以探索这项前景光明的技术的潜力。

In a recent call DFG has funded Magnetic Particle Imaging (MPI) scanners in order to provide researchers the opportunity to explore the potential of this imaging method. This requires clarifying the fundamentals of the novel imaging modality, such as, e.g., detection limits and image resolution of the MPI-scanners. Further peculiar questions will emerge from particular medical applications resulting from the specific local configuration of the MPI-tracer, e.g., in a vascular system or in a tumor.This project aims to establish a metrological infrastructure to accomplish controlled and validated experimental conditions, which will serve as a sound basis for a quantitative MPI.To this end, dedicated phantoms shall be developed and provided, by which individual imaging properties of an MPI scanner can be metrologically monitored. In particular the resolution as well as quantification of tracer amount and distribution in realistic medical environments will be addressed. Further, the congruence of anatomy and tracer distribution at a MRT-MPI coregistration shall be investigated. In addition to MRT we will employ magnetorelaxometry as an independent, spatially resolving reference technique to assess MPI results.For realistic examination of the MPI scanner performance the phantoms have to reflect the essential properties of the intended medical MPI application in a controlled manner. This comprises concentration variations, mobility and viscosity of the MPI tracer, as well as velocity, temperature, viscosity, and diameter of the physiological medium (blood).By this approach the validity of the MPI measurements in an in-vivo setting will be increased and the design of preclinical studies will be put on a reliable, sound basis increasing the prospects of success of these projects. As a consequence the number of animal testing can be reduced. The resulting long-term stable phantoms will be made available to physicians and physicists who work with the two DFG-funded MPI scanner sites for exploring the potential of this promising technique.