Even the most advanced imaging systems, computed tomography and magnetic resonance imaging, have been in use for several decades now. But a new modality that images magnetic particles in the bloodstream and which could help make heart studies more efficient is on the horizon.

Royal Philips Electronics, which invented the technology, said this week it helped launch a German consortium whose goal is to have a whole-body magnetic particle imaging device available for proof-of-concept demonstrations by 2013.

"It's a totally new imaging technology," Steve Klink, a spokesman for Philips, told DOTmed News. "The only thing in common [with MRI] is there are magnets."

The German government has pledged about 10.6 million euros ($13.9 million), about half of the consortium's goal of 20.3 million euros ($26.6 million), which will be paid by the other partners, to develop the demonstration device.

In essence, with magnetic particle imaging, or MPI, the imaging unit detects the magnetic properties of iron oxide nanoparticles - essentially, the same stuff as rust - injected in the body.

It works like this. The nanoparticles are injected into the patient as a bolus, explains Klink, which means the particles don't distribute evenly, but rather travel through the cardiovascular system together as a cloud, perfusing the heart muscle, entering the heart chambers and going through the lungs.

The MPI scanner then detects the magnetic particles, which it quantitatively measures. It can also render a 3-D image, Klink said.




Medically, the company is looking to use it either for stress tests or to guide cardiovascular interventions. One of the main possible benefits of the modality is it's sort of an all-in-one system, the company said, doing multiple tests that would normally have to be spread out among different technologies. "With one single measurement, you get information about what's called the ejection fraction, the wall motion, blood flow, speed and also the perfusion of the heart muscles," Klink said.

Decade-old concept

The concept of the technology is almost a decade old, and was dreamt up by MRI researchers Bernhard Gleich and Juergen Weizenecker at Philips' laboratory in Hamburg, Germany. The researchers reasoned that iron-oxide nanoparticles, already used as contrast agents to enhance contrast on MRI images, could be detected outright by a different type of magnetic scanner, possibly boosting the signal-to-noise ratio of the images.

Progress on the technology has been chugging along since then. In 2005, Nature published the first 2-D images captured with the device. Then in 2008, Philips created a small scanner with a 3-centimeter bore, allowing it to get the first 3-D images of the cardiovascular activity of a live mouse. This meant scanning a mouse's tiny, 6-millimeter heart, fluttering at 240 beats a second. "With MPI, we can accurately image that activity," Klink said.

For the mouse study, the researchers used Resovist, a contrast agent already in human use in Europe for liver imaging, but one of the goals of the consortium is to develop an agent "optimized" for MPI. On that, consortium partners Bayer Schering Pharma AG, Miltenyi Biotec, Charité-Universitätsmedizin Berlin and the Physikalisch-Technische Bundesanstalt are all at work, Philips said.

The Dutch electronics giant is also working with its consortium partner University of Lübeck to scale up the technology. But the company says they have to advance step-by-step. "Going from a 3-centimeter to a whole-body system is too big a leap to do at once," Klink said. That's why only a few months ago, Philips designed a larger scanner with a 12-centimeter opening, likely for tests with imaging phantoms.

One hope is the technology will allow doctors to be able to toggle the optimization between sensitivity, speed and resolution, with doctors choosing to maximize two modes at the expense of the third, based on what sort of information they're looking for, Klink said.

According to Philips, current resolution is about 1.5 millimeters along one axis, and 3 millimeters along the others, but theoretically, the maximum resolution is below 1 millimeter. The fastest acquisition time is 0.02 seconds. By comparison, MRI acquisition is between 1 and 100 seconds, and PET is 800 seconds, Klink said.

For the preclinical model, the German business Bruker Biospin is working on building a system that combines MPI and MRI, either fully integrated in one hybrid unit or spaced apart as in Philips' recently developed PET-MRI unit.

But for humans, don't expect getting a stress test on one of these any time soon. Realistically, it's still five to 10 years away, even as a research tool in the clinic, Klink said.

"This is really a long-term research project," Klink said. "But our hope is, three years from now, we'll have proven MPI for whole body measurement."