Development of an Open-Sided Magnetic Particle Imaging System With Amplitude Modulation-Based Reconstruction

Magnetic particle imaging (MPI) is a rapid and sensitive imaging technique that can be used to measure the spatial distribution of superparamagnetic iron oxide (SPIO) nanoparticles, which can be applied to vascular and perfusion imaging, cancer imaging, hyperthermia, drug treatments, and intraoperative navigation. Although closed-bore conventional MPI scanners offer the advantage of high coil efficiency, they significantly increase the risk of claustrophobia and panic attacks, may not accommodate all body shapes and sizes, are challenging to integrate with other medical modalities, and face several limitations when scaled for human use. Open-sided MPI with amplitude modulated (AM) has the potential to overcome these above issues due to the accessibility of imaging objects from sides without coil size constraints and using a low-amplitude high-frequency excitation field combined with a low-frequency high-amplitude drive field. In this article, we develop a compact open-sided MPI system utilizing a mechanically rotated 3-D field-free line (FFL) with permanent magnets for energy efficiency. The AM MPI method along with open gradiometer coils with a packaged configuration enhances uniform sensitivity. The developed system can achieve a field of view (FOV) of $40\times 40\times 40$ mm3. To obtain guidance on working parameters for the AM method and compare the performance of parameters with the X-space method, theory was developed, and results were simulated and experimentally verified by a developed scanner using AM for high resolution and sensitivity, avoiding heating issues.