Towards human-scale magnetic particle imaging: development of the first system with superconductor-based selection coils.

Magnetic Particle Imaging (MPI) is an emerging tomographic modality that allows for precise three-dimensional (3D) mapping of magnetic nanoparticles (MNPs) concentration and distribution. Although significant progress has been made towards improving MPI since its introduction, scaling it up for human applications has proven challenging. High-quality images have been obtained in animal-scale MPI scanners with gradients up to 7 T/m/µ0, however, for MPI systems with bore diameters around 200 mm the gradients generated by electromagnets drop significantly to below 0.5 T/m/µ0. Given the current technological limitations in image reconstruction and the properties of available MNPs, these low gradients inherently impose limitations on improving MPI resolution for higher precision medical imaging. Utilizing superconductors stands out as a promising approach for developing a human-scale MPI system. In this study, we introduce, for the first time, a human-scale amplitude-modulated (AM) MPI system with superconductor-based selection coils. The system achieves an unprecedented magnetic field gradient of up to 2.5 T/m/µ0 within a 200 mm bore diameter, enabling large fields of view of 100 × 130 × 98 mm3 at 2.5 T/m/µ0 for 3D imaging. While obtained spatial resolution is in the order of previous animal-scale AM MPIs, incorporating superconductors for achieving such high gradients in a 200 mm bore diameter marks a major step toward clinical MPI.

Design, construction, and operation of a 2 T 240 mm conduction-cooled defect-irrelevant winding (RE) Ba2Cu3O7-x magnet.

In order to explore the applicability of superconducting magnets in a magnetic field range of 3 T or less, where superconducting magnets have not been much used so far, a prototype magnet development project has been launched in collaboration with Hanmi Techwin Corporation and Seoul National University. As a result of the project, here we report the design, construction, and operation results of a 2 T 240 mm defect-irrelevant winding (DIW) (RE) Ba2Cu3O7-x (REBCO) magnet. First, design goals were set considering its potential usage in industrial fields, and a 2 T 240 mm-bore multi-width no-insulation high-temperature superconductor magnet was designed accordingly. Based on the design, a total of 15 double pancake (DP) coils were wound, regardless of defects in REBCO tapes, and assembled together. After being installed in a conduction cooling system, the magnet was tested at a temperature of <20 K, and a magnetic field of 2 T at the magnet center was successfully generated with a total of four DP coils containing multiple defects. Based on the experimental results, the additional considerations required for the DIW approach at the magnet level are discussed.