A brief examination of the human body reveals a sophisticated and well-organized biological system. Physicists have developed a novel imaging technology suitable for human usage. This does not necessitate the use of radioactive markers or radiation.
Computed tomography, magnetic resonance imaging, positron emission tomography, and ultrasound are all imaging modalities that have become crucial in the medical field. Each method not only provides physicians with unique insights into people’s insides, but also allows them to form judgments regarding abnormalities or functional processes in the human body.
A team of physicists and medical specialists from Julius-Maximilians-Universität Würzburg (JMU) has now succeeded in developing another – and radiation-free – imaging system for human use. Magnetic Particle Imaging (MPI) is the term for it. It is possible to visualize dynamic processes in the human body, such as blood flow, using the portable scanner they developed.
This research was led by Professor Volker Behr and Dr. Patrick Vogel of the University’s Institute of Physics, and the findings have been published in the journal Nature Scientific Reports.
As with positron emission tomography, which relies on the administration of radioactive substances as markers, this method has the great advantage of being sensitive and fast without’seeing’ interfering background signals from tissue or bone.
Volker Behr
A sensitive and fast alternative
Magnetic particle imaging, as the name implies, is a technique for directly visualizing magnetic nanoparticles. Because nanoparticles of this type do not form naturally in the human body, they must be supplied as markers. “As with positron emission tomography, which relies on the administration of radioactive substances as markers, this method has the great advantage of being sensitive and fast without’seeing’ interfering background signals from tissue or bone,” Volker Behr adds.
MPI is not based on the detection of gamma rays from a radioactive tracer, as positron emission tomography is, but on the response signal of magnetic nanoparticles to changing magnetic fields.
“In this process, the magnetisation of nanoparticles is specifically manipulated with the help of external magnetic fields, whereby not only their presence but also their spatial position in the human body can be detected,” says physicist Patrick Vogel, first author of the publication.
A small scanner for big insights
The MPI concept is not novel. The Philips business was able to exhibit the first photos of this unique technology in a small demonstrator as early as 2005, although it could only capture samples a few centimetres in size. And the development of instruments appropriate for human examination proved more challenging than anticipated, resulting in enormous, heavy, and expensive structures.
In 2018, Professor Volker Behr and Patrick Vogel led a team that discovered a novel approach to achieve the complicated magnetic fields required for imaging in a significantly smaller design. The scientists were successful in applying the unique concept in an MPI scanner (interventional Magnetic Particle Imaging — iMPI) specifically constructed for intervention in a multi-year research project financed by the German Research Foundation (DFG).
“Our iMPI scanner is so small and light that you can take it almost anywhere,” Vogel adds. The authors illustrate the scanner’s mobility in a simultaneous real-time measurement in comparison with a specific X-ray instrument, which is the standard device in angiography in university hospitals. The researchers, coordinated by Professor Thorsten Bley and Dr. Stefan Herz of the Würzburg University Hospital’s Interventional Radiology Department, carried out the measurements on a realistic vascular phantom and analyzed the initial photographs.
“This is a significant first step toward radiation-free intervention. MPI has the potential to change this field for the better,” said Dr Stefan Herz, senior author of the publication.
Next steps in research
In addition to further exciting measurements with the iMPI device, the two physicists are now working on further developing their scanner. The main goal is to further improve the image quality.
