UC Berkeley

Magnetic particle imaging (MPI) is a new and rapidly developing imaging modality. Here we explore new ways to use MPI for molecular imaging and theranostic applications. A major focus is exploring methods to leverage the magnetic relaxation dynamics associated with the tracers used in MPI. In the context of canonical MPI implementations, these dynamics can reduce resolution and signal; however, they are also a source of molecular imaging contrast. In the first part of this thesis, we experimentally characterize relaxation in the canonical sinusoidal MPI implementation and explore novel ways to exploit this relaxation for colorized imaging and theranostic applications. In the second part, we describe a new approach to signal encoding in MPI that we call pulsed MPI (pMPI). We show that pMPI can allow one to fully prevent relaxation-induced resolution loss and can even provide ways to improve resolution over traditional continuous wave encoding techniques. Furthermore, pMPI can be leveraged to directly quantify magnetic relaxation that does occur and report this information in an imaging format as relaxation images (in contrast to the standard tracer mass/concentration images). Such approaches may pave the way for greatly improved color MPI and related molecular imaging methods. We believe a major takeaway from this work is that there remains significant untapped potential in MPI by way of unexploited physics. We believe development of these possibilities will be an exciting part of our field's future.