Abstract
Magnetic Particle Imaging (MPI) is a novel imaging technique that visualizes the spatial distribution of magnetic
nanoparticles by detecting their nonlinear magnetization responses under an oscillating magnetic field. Since its principle was first proposed by Gleich and Weizenecker in 2005, MPI has attracted increasing attention, particularly for biomedical applications such as vascular imaging and brain perfusion monitoring. This article provides an overview of MPI principles, system configurations, and recent technological developments. I introduce the generation and detection of MPI signals based on field-free regions (FFP/FFL), describe representative instrument designs ranging from small preclinical setups to emerging human-scale systems, and highlight the role of superparamagnetic iron oxide nanoparticles (SPIONs) as biocompatible tracers. Advances in nanoparticle surface engineering and signal processing methods have improved spatial resolution, multi-tracer imaging, and functional applications such as temperature mapping. Compared to existing modalities, MPI offers radiation-free, high-sensitivity imaging similar to PET, with potential for complementary clinical use in environments lacking nuclear medicine facilities. Nevertheless, significant challenges remain, including device scalability, power requirements for human-scale systems, and integration with anatomical imaging techniques such as CT or MRI. Continued research on instrumentation, tracer development, and hybrid imaging approaches will be essential to realize the clinical potential of MPI.
