Sequential Scan-Based High-Resolution 3-D Open-Sided Magnetic Particle Imaging System

Magnetic particle imaging (MPI) is an emerging molecular imaging technique that relies on the nonlinear magnetization response of superparamagnetic iron oxide nanoparticles. Open-sided MPI (OS-MPI) has attracted considerable interest for its potential to enhance interventional procedures. However, improving the spatial resolution of OS-MPI poses a significant challenge, mainly due to the inefficiencies of selection coils in generating, rotating, and shifting a high-gradient field-free line (FFL). To address this issue, we propose a novel approach called the permanent magnet-based sequential scan to develop a high-resolution 3-D OS-MPI system with ultralow power consumption. By utilizing permanent magnets, we can create high-gradient selection fields without any power consumption. The sequential scan technique involves rotating the FFL angle by angle and shifting the FFL layer by layer. To maintain thermal stability during sequential scans, we used drive coils wound with hollow copper wires and implemented forced oil cooling. Additionally, measures such as copper shielding, feed-through compensation, and filtering were employed to minimize interference from the permanent magnets, drive coils, and motor drivers. Experimental results demonstrated that the developed system successfully achieved a spatial resolution of 1 mm while operating with an overall low power consumption of 282.16 W.