Development of a Rabbit-Scale Amplitude-Modulated Single-Sided MPI With Flattened FFL Trajectory-Based Reconstruction

Abstract

Magnetic particle imaging (MPI) is progressing toward clinical applications. These applications demand a large, unobstructed field of view (FOV) and high temporal resolution, making single-sided MPI a promising solution. In this configuration, all hardware components are placed on one side, allowing for a large imaging volume for interventional procedures and accommodating patients or devices of various sizes and shapes. However, conventional field-free line (FFL) single-sided MPI poses challenges in flattening the FFL trajectory, limiting FOV size, and reducing temporal resolution for 3-D image reconstruction in nonuniform magnetic fields. In this article, an amplitude modulation (AM) reconstruction method was applied with separate drive and excitation coils to effectively flatten the FFL trajectory in the horizontal plane for a single-sided MPI configuration. The system was optimized to achieve a larger FOV depth, reduced power consumption, and minimized nonuniform magnetic field along the FFL. As a result, we developed an AM single-sided MPI system with a threefold increase in FOV (40 × 40 × 30 mm3) with significantly enhanced temporal resolution of 2 s per average projection compared to existing conventional single-sided MPI. Moreover, 3-D image reconstruction using an electrically controlled flattened FFL at variable heights up to 30 mm achieved higher temporal resolution (225 s per 3-D image), reduced artifacts, and improved spatial resolution. The system demonstrated a 1-D sensitivity of 60 μgFe and phantom separation capability of 2 mm. We successfully designed, developed, and validated a rabbit-scale AM single-sided MPI with a flattened FFL trajectory, addressing the challenges in the existing conventional FFL-based single-sided MPI toward biological applications. These advancements establish the AM single-sided MPI as a promising solution for imaging near-surface structures in rabbit-scale applications, such as sentinel lymph node biopsy for breast cancer, and lay the groundwork for future human-scale single-sided MPI systems design. © 1963-2012 IEEE.