Magnetic Particle Imaging (MPI) is an emerging molecular imaging technique that directly detects superparamagnetic nanoparticle tracers. First introduced in 2005 by Gleich and Weizenecker, MPI sensitively detects nanoparticle tracers using their magnetic nonlinearity with magnetic gradient fields. The images produced are specific to the tracer, without any confounding signal from tissue. The resulting images resemble those taken with nuclear medicine and are often paired with an anatomic modality such as CT or MRI. Similar to MRI, MPI does not use ionizing radiation and the signal does not change with tissue depth.
Magnetic Particle Imaging (MPI) is an emerging molecular imaging technique that directly detects superparamagnetic nanoparticle tracers. First introduced in 2005 by Gleich and Weizenecker1, MPI sensitively detects nanoparticle tracers using their magnetic non-linearity with magnetic gradient fields.2,3 The images produced are specific to the tracer, linearly quantifiable, without any confounding signal from tissue. The resulting images resemble those taken with nuclear medicine and are often paired with an anatomic modality such as CT or MRI. Similar to MRI, MPI does not use ionizing radiation and the signal does not change with tissue depth. Stable tracers enable longitudinal imaging over days to weeks.
The most common tracers for MPI are superparamagnetic iron oxide nanoparticles (SPIONs). These SPIONs have had a long history of use as an MRI contrast agent, where they produce hypointense signals in T2-weighted images. This provides the advantage an inherently multimodality tracer for imaging with both MRI and MPI. To date, most MPI work has been performed with ferucarbotran, a clinically approved tracer. However, recent advances in particles designed specifically for MPI have shown promise for significant advances to the field of MPI.
To date MPI has been utilized in a variety of applications, including: vascular imaging4, cell tracking5,6, inflammation detection5,7, neurological conditions7, and theranostic hyperthermia5.
This educational session will highlight:
1. Introduction to MPI and Molecular Imaging
2. Theory of MPI – from the perspective of an MRI researcher
3. Current Pre-clinical Applications
4. Future clinical perspectives
1. Gleich, Bernhard, and Jürgen Weizenecker. "Tomographic imaging using the nonlinear response of magnetic particles." Nature 435.7046 (2005): 1214.
2. Saritas, Emine U., et al. "Magnetic particle imaging (MPI) for NMR and MRI researchers." Journal of Magnetic Resonance229 (2013): 116-126.
3. Knopp, T., N. Gdaniec, and M. Möddel. "Magnetic particle imaging: from proof of principle to preclinical applications." Physics in Medicine & Biology 62.14 (2017): R124.
4. Weizenecker, J., et al. "Three-dimensional real-time in vivo magnetic particle imaging." Physics in Medicine & Biology54.5 (2009): L1.
5. Chandrasekharan, Prashant, et al. "A perspective on a rapid and radiation-free tracer imaging modality, magnetic particle imaging, with promise for clinical translation." The British journal of radiology 91.1091 (2018): 20180326.
6. Bulte, J. W. M. "Superparamagnetic iron oxides as MPI tracers: A primer and review of early applications." Advanced drug delivery reviews (2018).
7. Wu, L. C., et al. "A Review of Magnetic Particle Imaging and Perspectives on Neuroimaging." American Journal of Neuroradiology 40.2 (2019): 206-212.