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

在最近的一次呼吁中，DFG资助了磁颗粒成像（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，例如在血管系统或肿瘤中，因此在特定的医学应用中会出现进一步的特殊问题。该项目旨在建立一个计量基础设施，以实现可控和验证的实验条件，这将为定量MPI奠定坚实的基础。为此，应开发并提供专用的模型，通过该模型可以计量地监测MPI扫描仪的单个成像特性。特别是在现实的医疗环境中，将解决示踪剂的数量和分布的分辨率和定量。此外，在MRT-MPI共配准解剖结构和示踪剂分布的一致性应进行调查。除MRT外，我们将采用磁松弛法作为独立的空间分辨参考技术来评估MPI结果。为了对MPI扫描仪性能进行真实的检查，这些幻象必须以受控的方式反映预期医用MPI应用程序的基本特性。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测量的有效性将得到提高，临床前研究的设计将建立在可靠、健全的基础上，增加了这些项目成功的前景。因此，动物试验的数量可以减少。由此产生的长期稳定的幻影将提供给与dfg资助的两个MPI扫描仪站点合作的医生和物理学家，以探索这种有前途的技术的潜力。

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.