Philips demonstrates feasibility of a new imaging technique based on magnetic particles

June 30, 2005

Scientists at Philips Research have been active in developing a completely new imaging technique called Magnetic Particle Imaging (MPI) and have demonstrated the feasibility of the technique. Although still in the early research stages, the new technique offers potential as a valuable addition to the current armory of imaging techniques for medical imaging and materials analysis. Results of the work have been published in the June 30 edition of Nature.

The idea behind MPI is to produce spatial images by measuring the magnetic fields generated by magnetic particles in a tracer. While previous approaches to realize this resulted in relatively poor spatial resolution or low sensitivity, the method invented by Philips generates high-resolution images at low dosages. This is achieved by combining the nonlinear magnetization curve of the small magnetic particles with an inhomogeneous magnetic field.

The particles are subjected to a time-varying sinusoidal magnetic field with sufficiently high amplitude to drive their magnetization into the non-linear region. This induces high-frequency harmonics in the resulting time-varying magnetization that can be easily extracted from the fundamental or drive frequency by filtering. If the magnetic particles are simultaneously exposed to a time-constant magnetic field of sufficiently large magnitude, the particle magnetization becomes saturated and the generation of harmonics is suppressed. This opens the possibility of producing an imaging device in which the time-constant field is constructed such that the magnitude of the field drops to zero at a single point in the field known as the 'field-free point' and increases in magnitude towards the edges. A signal containing harmonics will then be detected only from magnetic particles located in the vicinity of the field-free point; at all other points the magnetic particles are fully saturated by the time-constant field and produce no signal. So by scanning the field-free point through the volume of interest, it is possible to develop a 3D image of the magnetic-particle distribution. Movement of the field-free point can be achieved either mechanically or by field-induced movement. Both techniques have been investigated by the Philips researchers.

The researchers have evaluated the new MPI technique using commercially-available magnetic tracers. Conducted on 'phantom' objects, these investigations have demonstrated the feasibility of MPI and show that it has potential to be developed into an imaging method characterized by both high spatial resolution and high sensitivity. The expected high sensitivity leads to the presumption that the technique could become a valuable addition to other medical imaging modalities.

Besides its potential in medical imaging, MPI also shows promise as an imaging technique for materials research - specifically in the investigation of cracks and cavities in insulating materials like polymers or ceramics.

Source: Philips

Explore further: NIST PET phantoms bring new accuracy to medical scans

Related Stories

NIST PET phantoms bring new accuracy to medical scans

July 29, 2015

Teaming with a medical equipment company, researchers at the National Institute of Standards and Technology (NIST) have demonstrated the first calibration system for positron emission tomography (PET) scanners directly tied ...

Imaging glucose uptake activity inside single cells

July 17, 2015

Researchers at Columbia University have reported a new approach to visualize glucose uptake activity in single living cells by light microscopy with minimum disturbance. In a recent study published in Angewandte Chemie International ...

New technique enables magnetic patterns to be mapped in 3-D

July 7, 2015

An international collaboration has succeeded in using synchrotron light to detect and record the complex 3-D magnetization in wound magnetic layers. This technique could be important in the development of devices that are ...

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

Image: Hubble sees a dying star's final moments

July 31, 2015

A dying star's final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star's demise is still quite ...

Binary star system precisely timed with pulsar's gamma-rays

July 31, 2015

Pulsars are rapidly rotating compact remnants born in the explosions of massive stars. They can be observed through their lighthouse-like beams of radio waves and gamma-rays. Scientists at the Max Planck Institute for Gravitational ...

Exoplanets 20/20: Looking back to the future

July 31, 2015

Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.

Earth flyby of 'space peanut' captured in new video

July 31, 2015

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.