The hardware, tracer, and signal processing methods of magnetic particle imaging: A review

Magnetic Particle Imaging (MPI) has advanced rapidly from its first conceptualization, showing promise as a viable clinical imaging modality. Despite its promise, several aspects of MPI, such as hardware design, tracer design, and image reconstruction method, still require further technical development to overcome their current limitations. This review provides the basic concept for MPI, introduces the limitations of upscaling MPI, and discusses several aspects of MPI development. Among them are the advantages and disadvantages of using different field-free regions (FFR), bore configurations, elaborating on the challenges in upscaling, describing the optimal characteristics of MPI tracers, discussing tracer synthesis methods and biocompatible coatings, tracer toxicity reports, and finally a basic explanation regarding the various image reconstruction methods. Additionally, this review provides several examples of state-of-the-art MPI devices and prototypes with varying bore designs, FFR designs, magnetic field sources, and intended use cases to demonstrate both the wide range of applications and the progress of recent research in MPI. With all this information compiled, this review serves to shed insight for researchers in the field of MPI or those intending to enter the world of MPI. It is hoped that this review will encourage the future development of MPI, accelerating its viability for clinical implementation.