Where and when

speaker: Wolfgang Erb  
affiliation: Department of Mathematics, Università degli Studi di Padova, Italy 
date: Friday, December 6, 2024 – 2.30 pm (Italian time)  
venue: Genoa (Italy), Polo Valletta Puggia – Università di Genova: DIBRIS-DIMA (room 711)  
link: Google Meet

Data-optimized models for reconstruction in Magnetic Particle Imaging using realistic magnetic fields

abstract: We present a data-optimized 3D model for Magnetic Particle Imaging (MPI) that is able to incorporate realistic magnetic fields for the reconstruction of the spatial distribution of para-magnetic tracers. In real MPI scanners, the generated magnetic fields have distortions that lead to deformed magnetic low-field volumes with the shapes of ellipsoids or bananas instead of ideal field-free points (FFP) or lines (FFL), respectively. Most of the common model-based reconstruction schemes in MPI use however idealized assumptions of an ideal FFP or FFL topology and, thus, generate artifacts in the reconstruction. Our approach allows to incorporate calibration measurements of the magnetic fields into the imaging model. The new data-optimized model is able to deal with distortions and can generally be applied to dynamic magnetic fields that are approximately parallel to their velocity field. We show how this 3D model can be discretized and inverted algebraically in order to recover the magnetic particle concentration. To model and describe the magnetic fields, we use decompositions of the fields in spherical harmonics. We complement the description of the new model with several simulations and experiments exploring the effects of magnetic field distortions and of model parameters on the reconstruction.