Triphase MagRing-MPI: Topology Evolution and Vector Space Control for Electronic FFL Scanning

To develop and validate a Triphase MagRing magnetic particle imaging (MPI) framework for electronically rotatable and steerable field-free-line (FFL) control based on topology evolution and vector-space control in a large-bore prototype.

A Triphase MagRing-MPI architecture was formulated using the Clarke-Park transform. Three wiring topologies were compared in controllability, spectral behavior, and engineering complexity. A 200-mm-bore air-core prototype was evaluated by magnetic-field mapping, current-spectrum analysis, thermal monitoring, robustness simulation with measured disturbance injection, and head-phantom imaging.

The prototype achieved controllable FFL generation, rotation, and steering with a measured gradient of 0.071 T/m. Y-3 showed the cleanest current spectra and the simplest implementation. The prototype remained thermally stable during 35 min of operation under the tested duty cycle. Head-phantom imaging successfully localized tracer targets within a 120 × 120mm$^{2}$ field of view. Preliminary simulations with soft magnetic cores indicated that the central gradient could be increased to 2.15 T/m, suggesting further room for optimization.

The proposed framework enabled stable electronically rotatable and steerable FFL operation in the present prototype and identified Y-3 as the preferred wiring topology.

This work provides an engineering validation of MagRing-MPI in a triphase, three-pole-pair configuration, supports future extension to systems with more pole pairs and more phases, and provides an engineering basis for future large-bore MPI system development.