High-Resolution Magnetic Particle Imaging via Rotational Excitation at Low-Gradient Fields

Abstract

Magnetic particle imaging (MPI) is an emerging biomedical imaging modality distinguished by high-sensitivity, real-time capability, and freedom from ionizing radiation. However, the practical application of MPI has been hindered by the need for high-gradient fields to achieve fine spatial resolution, which substantially increases system complexity, power consumption, and cost. To overcome this limitation, this article presents a high-resolution MPI (HR-MPI) method. HR-MPI employs a fusion reconstruction scheme tailored for rotating data sequences. It compensates for multidirectional signal and gradient losses, enabling high-resolution imaging in low-gradient fields. A field-free line (FFL)-based 2-D MPI scanner with a rotating excitation is developed to excite superparamagnetic iron oxide nanoparticles (SPIONs) from multiple directions, enhancing imaging adaptability. The scanner employs a narrowband and low-gradient field configuration to achieve high resolution while mitigating the traditional resolution-feasibility tradeoff in MPI. Experimental results demonstrate a 1-mm spatial resolution achieved with only 0.9 T/m. This approach offers a promising pathway toward practical MPI applications.