Magnetic Particle Imaging in Vascular Imaging, Immunotherapy, Cell Tracking, and Noninvasive Diagnosis

Figure 5

X-space MPI with a field-free line scanner. We illustrate the functioning of x-space MPI using a custom-built, vertical-bore 6.3 T/m field-free line (FFL) scanner. The FFL is created by a specialized iron return core electromagnet that serves as a slow-shift magnet as well. 2D-projection images are acquired by shifting the FFL in the x-y plane while translating the sample in the z-direction. In MPI, a time-varying field is applied, and only the particles at the FFL flip in response. The flip generates a signal in a receiver coil due to Faraday’s law of induction and rastering the FFL allows the signal to be spatially localized. The MPI scanner allows for 2D projection and 3D tomographic imaging of the spatial distribution of superparamagnetic iron oxide nanoparticle tracers (SPIOs). Classical projection reconstruction algorithms can be implemented to reconstruct 3D MPI images from 2D projections [6, 11, 88]. Image reproduced under the Creative Common license CC-BY-4 from Chandrasekharan et al., Nanotheranostics, 2021 [23].