University of Bremen - Inverse problems and magnetic particle imaginghttps://www.uni-bremen.de/en/techmath/research/inverse-problems-and-magnetic-particle-imagingDescription of the Inverse Problems and MPI TeamUniversity of BremenTue, 18 Jan 2022 23:51:06 +0100Tue, 18 Jan 2022 23:51:06 +0100University of BremenModellinghttps://www.uni-bremen.de/en/techmath/research/inverse-problems-and-magnetic-particle-imaging#c328009Finding a sufficiently accurate model to reflect the behavior of large numbers of particles for MPI remains an open problem. As such, reconstruction is still computed using a measured forward operator obtained in a time-consuming calibration process. The model commonly used to illustrate the imaging methodology and obtain first model-based reconstructions relies on substantial model simplifications. One needs to take into account the magnetization dynamics of the nanoparticles' magnetic moment (red) such as Brownian (left) and Neel rotation (right) into the direction of the applied field (green). By neglecting particle-particle interactions, the forward operator can be expressed by a Fredholm integral operator of the first kind which yields the the inverse problem for image reconstruction.
Contentcontent-328009Wed, 17 Feb 21 07:29:00 +0100https://www.uni-bremen.de/en/techmath/research/inverse-problems-and-magnetic-particle-imaging#c328012Since the discovery of X-ray tomography in the 1970s, imaging techniques have continuously revolutionized medical diagnostics. Nowadays, there are various tomographic procedures in the clinical environment, which are applied differently due to their specific advantages and disadvantages. The most important procedures are computed tomography (CT), magnetic resonance imaging (MRI), and various functional technologies such as PET (positron emission tomography) and SPECT (single-photon emission computed tomography).
Since the early 2000s, Magnetic Particle Imaging (MPI) has made its way into research-based medicine. The basic idea is to inject patients with magnetic nanoparticles, iron oxide particles called tracers, and locate their concentration in the body with externally applied magnetic fields. The technique is radiation-free and has a very high temporal resolution. Currently, this technology has significant challenges that are being investigated in our team. These include detailed mathematical modeling of the measurement process. In addition, due to the current lack of data, many of the most common data-driven methods are not directly applicable.Contentcontent-328012Wed, 17 Feb 21 08:07:25 +010060