Magnetic particle imaging: introduction to imaging and hardware realization

Z Med Phys. 2012 Dec;22(4):323-34. doi: 10.1016/j.zemedi.2012.07.004. Epub 2012 Aug 19.


Magnetic Particle Imaging (MPI) is a recently invented tomographic imaging method that quantitatively measures the spatial distribution of a tracer based on magnetic nanoparticles. The new modality promises a high sensitivity and high spatial as well as temporal resolution. There is a high potential of MPI to improve interventional and image-guided surgical procedures because, today, established medical imaging modalities typically excel in only one or two of these important imaging properties. MPI makes use of the non-linear magnetization characteristics of the magnetic nanoparticles. For this purpose, two magnetic fields are created and superimposed, a static selection field and an oscillatory drive field. If superparamagnetic iron-oxide nanoparticles (SPIOs) are subjected to the oscillatory magnetic field, the particles will react with a non-linear magnetization response, which can be measured with an appropriate pick-up coil arrangement. Due to the non-linearity of the particle magnetization, the received signal consists of the fundamental excitation frequency as well as of harmonics. After separation of the fundamental signal, the nanoparticle concentration can be reconstructed quantitatively based on the harmonics. The spatial coding is realized with the static selection field that produces a field-free point, which is moved through the field of view by the drive fields. This article focuses on the frequency-based image reconstruction approach and the corresponding imaging devices while alternative concepts like x-space MPI and field-free line imaging are described as well. The status quo in hardware realization is summarized in an overview of MPI scanners.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Algorithms
  • Computers
  • Contrast Media*
  • Electromagnetic Fields
  • Equipment Design
  • Humans
  • Image Interpretation, Computer-Assisted / instrumentation*
  • Image Interpretation, Computer-Assisted / methods*
  • Image Processing, Computer-Assisted / instrumentation*
  • Image Processing, Computer-Assisted / methods*
  • Magnetic Resonance Imaging / instrumentation*
  • Magnetic Resonance Imaging / methods*
  • Magnetite Nanoparticles*
  • Molecular Imaging / instrumentation
  • Molecular Imaging / methods
  • Sensitivity and Specificity
  • Surgery, Computer-Assisted / instrumentation*
  • Surgery, Computer-Assisted / methods*


  • Contrast Media
  • Magnetite Nanoparticles