Single-Sided Magnetic Particle Imaging Device With Offset Field Based Spatial Encoding

IEEE Transactions on Medical Imaging, vol. 44, pp. 1878–1889

Abstract

Single-sided Magnetic Particle Imaging (MPI) devices enable easy imaging of areas outside the MPI device, allowing objects of any size to be imaged and improving clinical applicability. However, current single-sided MPI devices face challenges in generating high-gradient selection fields and experience a decrease in gradient strength with increasing detection depth, which limits the detection depth and resolution. We introduce a novel spatial encoding method. This method combines high-frequency alternating excitation fields with variable offset fields, leveraging the inherent characteristic of single-sided MPI devices where the magnetic field strength attenuates with distance. Consequently, the harmonic signals of particle responses at different spatial positions vary. By manipulating multiple offset fields, we correlate the nonlinear harmonic responses of magnetic particles with spatial position data. In this work, we employed an image reconstruction using a system matrix approach, which takes into account the spatial distribution of the magnetic field during the movement of the device within the field of view. Our proposed encoding approach eliminates the need for the classical selection field and directly links the spatial resolution to the strength and spatial distribution of the magnetic field, thus reducing the dependency of resolution on selection field gradients strength. We have demonstrated the feasibility of the proposed method through simulations and phantom measurements.

Authors 9

1. Qibin Wang

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China

2. Zhonghao Zhang

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China

3. Lei Li

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China

4. Franziska Schrank Aachen Department of Physics of Molecular Imaging Systems Medical Faculty Institute for Experimental Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   Department of Physics of Molecular Imaging Systems, Medical Faculty, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany

   Department of Physics of Molecular Imaging Systems, Medical Faculty, Institute for Experimental Molecular Imaging, RWTH Aachen University, Germany

5. Yu Zeng

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China

6. Pengyue Guo

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China

7. Harald Radermacher Aachen Department of Physics of Molecular Imaging Systems Medical Faculty Institute for Experimental Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   Department of Physics of Molecular Imaging Systems, Medical Faculty, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany

   Department of Physics of Molecular Imaging Systems, Medical Faculty, Institute for Experimental Molecular Imaging, RWTH Aachen University, Germany

8. Volkmar Schulz Aachen Department of Physics of Molecular Imaging Systems Medical Faculty Institute for Experimental Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   Department of Physics of Molecular Imaging Systems, Medical Faculty, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany

9. Shouping Zhu

   Xidian University

   Affiliation as printed

   School of Life Science and Technology, Xidian University, Xi’an, China