Inner vision in cardiology and beyond: A step on the road to portable scanning

It’s hard to imagine how medicine was practised without ultrasound, magnetic resonance imaging, and positron emission tomography. But once they were developed, it’s natural to assume these technologies would continually evolve, and researchers at the Julius-Maximilians-Universität Würzburg (JMU) in Germany say they have developed a device that can provide scans that are radiation-free with a portable device and what’s more, it’s ready for use on humans.

Magnetic particle imaging (MPI) uses a portable scanner which, rather than relying on ionising radiation or nephrotoxic contrast media, utilises magnetic fields to detect the spatial distribution of tracer agents composed of magnetic nanoparticles. However, these do not occur naturally in the human body, but rather must be administered as markers. First author Dr Patrick Vogel from JMU’s Institute of Physics explained: “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.”

The system could have some serious applications, not least in the area of cardiovascular disease. In conditions such as such as stroke, ischemic heart disease, and peripheral artery disease, minimally-invasive image-guided interventions now play a major role in finding out more about these diseases in individuals. These innovations have been driven by the development of specific instrumentation technology and increasingly sophisticated imaging technology.

X-ray fluoroscopy and digital subtraction angiography are regarded as the standard imaging modalities for these procedures; however, x-rays do involve radiation exposure not only for patients, but those administering them, and of course iodine-containing contrast media can potentially cause acute kidney damage.

“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,” explained Dr Vogel.

And when it comes to this system, size matters. It’s not a new concept. Back in 2005, Philips developed a small demonstrator model, but could only image samples a few centimetres in size. This led to attempts to upscale, which resulted in large, clunky, and awkward machines that were impractical.

Fast-forward to 2018 and the same authors of this study, which was published recently in Nature Scientific Reports, found a way to integrate the same effects into a far smaller design in the form of an MPI scanner specifically designed for intervention. The authors explain that the new interventional magnetic particle imaging (iMPI) is so portable that it can be taken almost anywhere. It has already been tested on a realistic vascular ‘vessel phantom’ and the authors say it has the potential to permanently change the field.