Development of Magnetic Particle Imaging for Quantitative Immune Cell Tracking
Abstract
The Foster lab has been developing cellular MRI tools for well over a decade using superparamagnetic iron oxide (SPIO)-based contrast agents for numerous applications cell tracking applications. SPIO are used to label cells which are indirectly detected as regions of signal loss. The main challenge with this technique is quantification of cell number, which is important for applications such as dendritic cell (DC)-based immunotherapies where cell number is used as a predictor of immunotherapeutic response.
Magnetic particle imaging (MPI) is a novel pre-clinical modality that shows promise for cell tracking. MPI directly detects the nonlinear magnetization response of superparamagnetic iron oxide nanoparticles (SPIO), without background signal or attenuation from tissues. This allows for high cellular sensitivity, specificity, and quantification of iron. With these advantages, MPI overcomes the challenges of cellular magnetic resonance imaging (MRI).
This thesis describes our three goals for implementing MPI as a sensitive and quantitative technique for cell tracking: (i) test commercially available SPIO for MPI, (ii) quantify DC migration in vivo and (iii) test and validate novel image parameters. We contributed to the advancement of this technology by detecting as few as 1000 DC (4.4 ng) in vivo. With clinical MPI systems currently being developed, this work contributed significantly towards the development, validation, and implementation of MPI as an advanced therapeutic cell tracking modality.