First Low Field Magnetic Particle Imaging System for Neurological Applications in Humans

磁粒子成像(MPI)是一种成像技术，它可以确定磁性纳米颗粒的局部分布。经过快速的技术发展，该方法目前正在进行临床前试验，在各种医学应用中已经显示出很高的潜力。特别是，MPI已经在颅脑创伤和中风等神经学问题以及脑动脉瘤成像方面取得了开创性的成果。然而，到目前为止，结果只能在小动物模型中显示，因为到目前为止开发的MPI扫描仪太小，无法在大型动物或人体上进行测量。该项目的目标是开发一种适用于人类检查的神经问题MPI扫描仪。在已经证明了可行性的原型的基础上，我们将设计一个最适合神经重症监护病房的监测任务的系统。由于其体积小和优化的线圈，它不需要专门的冷却，因此可以直接安装在患者的床上。该系统还可以在屏蔽室外运行，这要归功于有效的fi信号路由和对房间内干扰的检测。这使得能够在中风治疗后的几个小时内对患者进行永久监测，而不需要暴露在X射线下。到目前为止，这些患者的CT图像只在急性恶化和昂贵的情况下拍摄。现有的原型是作为Low-field MPI系统实现的，其水平方向的空间分辨率高达6 mm，垂直方向的空间分辨率高达28 mm，选择的field的梯度强度约为。0.2T/m。在本项目中，将设计一个二维激励单元和一个三维接收单元，满足三个基本要求。它们的fi效率很高，不需要主动冷却，它们在电气上是安全的，也可以毫不犹豫地用于人体实验，而且它们经过噪声优化，可以进一步提高现有原型的灵敏度。由于二维激发和三维接收，头部扫描仪将达到大约各向同性的分辨率。5毫米。通过优化测量顺序，扫描仪将达到约10%的高时间分辨率。对于边缘长度为100 mm的三维测量体积，为250 ms。对于数据重建，提出了考虑磁fi场缺陷的算法。所开发的多平面成像扫描仪和重建算法在模拟人头血管系统的真实flow模型上进行了测试。

Magnetic Particle Imaging (MPI) is an imaging technique that allows the local distribution of magnetic nanoparticles to be determined. After rapid technological development, the method is currently undergoing preclinical trials, in which it has already shown a high potential in various medical applications. In particular, MPI has already achievedpioneering results in neurological questions such as craniocerebral trauma and stroke, as well as in the imaging of brain aneurysms. So far, however, the results could only be shown in small animal models because the MPI scanners developed so far are too small for measurements on large animals or humans.The goal of this project is the development of an MPI scanner for neurological questions, which is also suitable for human examination. Based on a prototype with which the feasibility has already been demonstrated, we will design a system that is optimally suited for monitoring tasks in the neurological intensive care unit. Due to its small sizeand optimized coils, it does not require a dedicated cooling and can therefore be mounted directly on the patient’s bed. The system can also be operated outside shielded rooms thanks to efficient signal routing and the detection of disturbances in the room. This enables permanent monitoring of the patient in the hours following stroke treatmentwithout exposure to X-rays. Up to now, CT images of these patients are only taken in cases of acute deterioration and at great expense.The existing prototype is implemented as a low-field MPI system and achieves a spatial resolution of up to 6mm in the horizontal direction and 28 mm in the vertical direction with a gradient strength of the selection field of approx. 0.2 T/m. Within the project, a two-dimensional excitation unit and a three-dimensional receiver unit will be designed which meets three essential requirements. They are highly efficient and do not require active cooling, they are electrically safe and can also be used in human experiments without hesitation and they are noise optimized so that the sensitivity of the existing prototype can be further increased. Due to the two-dimensional excitation and three-dimensional reception, the head scanner will achieve an isotropic resolution of approx. 5 mm. By optimizing the measurement sequence, the scanner will achieve a high temporal resolution of approx. 250 ms for a three-dimensional measurement volume with an edge length of 100 mm. For data reconstruction algorithms are developed, which consider imperfections of the magnetic fields. The developed MPI scanner and the reconstruction algorithms are tested on realistic flow phantoms, which simulate the vascular system of a human head.