A better image

Magnetic Particle Imaging (MPI) is potentially a useful complementary technology to magnetic resonance imaging (MRI), but has been held back by the inferior quality of scans produced.

But now, a team at Philips Research said a successful test scan of a small object has suggested these problems can now be overcome. MPI could also have further applications in areas such as materials analysis and crack detection, Philips believes.

To test their idea, the team scanned a 9.4mm x 9.4mm plastic container filled with a contrast agent, demonstrating that a higher-resolution image can be produced by scanning the magnetic particles than is possible using an MRI scan.

For several decades scientists have been able to scan patients by injecting them with magnetic particles. But the technology has so far failed to take off because it provides an uneven image of the subject being scanned.

In the new Philips system, the magnetic particles are first subjected to a time-varying sinusoidal magnetic field. Due to this fact, they emit high-frequency harmonic signals that can be easily extracted by filtering. If the magnetic particles are simultaneously exposed to a time-constant magnetic field of sufficiently large magnitude, the particles become completely magnetized, or saturated, and the generation of harmonics is suppressed.