System Matrix Recording and Phantom Measurements with a Single-Sided Magnetic Particle Imaging Device

Abstract

Magnetic particle imaging (MPI) is a new imaging method, which uses superparamagnetic iron oxide nanoparticles as tracer material. Due to their tube-like design, most MPI devices have limited patient access. In this paper, an improved oil-cooled singlesided MPI device is presented that has the advantage that all coils, which are generating the magnetic fields or receiving the particle signal, are coplanar and on one side of the patient only. In consequence, the object, which will be scanned, is not limited in size. In this paper, a first 1-D image recorded with the new device is presented.Index Terms-1-D imaging, field-free point (FFP), magnetic particle imaging (MPI), reconstruction, single-sided MPI device.

Single-Sided Field-Free Line Generator Magnet for Multi-Dimensional Magnetic Particle Imaging

“…The operation of the focus coils is following: the first partial FOV (pFOV) is created by the original arrangement with the selection coils (1,2), the second pFOV is shifted to the left (see Fig. 1(b)) by using the coils (3,4) as the selection coils and the coil (1) as the z-drive coil, and the third pFOV is similarly shifted to the right by using the coils (3,5) as the selection coils and the coil (2) as the z-drive coil. Adding two more coils in the top layer to surround coils (1,2) would allow the x-drive operation within each pFOV.…”

“…For the small field curvatures ∆h ≈ x 2 /(2h 0 ), where h 0 = h(x = 0). This height variations can be corrected by applying an additional bias fieldB z (t) = −B D z (t), which can be achieved by modulating the current in the coil (3) or the coils (4,5). Thus for known displacements alonĝ x we can apply Eq.…”

“…As was pointed out before, the FFL trajectory in the xz-plane is not linear therefore for the cartesian encoding scheme an independent FFL height adjustment is required. Such an adjustment can be achieved either by the z-drive coil (3) or by the same coils (4,5) with the in-phase modulation of I 2 . Figure 7 shows the simulated magnetic field contour plots in the xz-plane that represent the adjusted constant-height trajectory from left to right due to the modulation current I 3 in the coil (3).…”

“…Here we propose a novel design of Selection-Drive (SD) coils for a single-sided device that is capable of 3-D image encoding. Moreover, different from the recent field-free point (FFP) based developments [5,6,7], in our geometry we utilize a more sensitive field-free line (FFL) configuration [8,9]. The design is capable generating a sufficient magnetic field gradient and drive fields so that the FFL can travel across a volume of a small animal or penetrate deep enough into human organs such as in the vascular or lymphatic systems for sentinel lymph node biopsy [10,11].…”

Neural Network Image Reconstruction for Magnetic Particle Imaging

“…Therefore, a regularization technique is necessary to retrieve an image with high resolution. Various iterative methods have been used for successful reconstruction of a particle image. However, such iterative methods have a problem in terms of the large computational cost incurred when compared to an analytic technique.…”