MPI imaging technology aims at human application

EINDHOVEN, The Netherlands—Stating that the development andcommercialization of preclinical MPI scanners are important steps towardsestablishing the technology for humans, Philips and Bruker BioSpin have signeda memorandum of understanding for the development of Magnetic Particle Imaging(MPI) scanners for the preclinical market.

The partnership will unite Philips' strength in medicalimaging and Bruker BioSpin's leadership in analytical magnetic resonanceinstruments and preclinical Magnetic Resonance Imaging (MRI). Under the termsof the agreement, Bruker BioSpin will develop and manufacture the preclinicalMPI scanner at its facilities in Ettlingen, Germany. Both parties intend toco-market the resulting solution. The two companies believe that the additionof MPI as a complementary preclinical imaging technique has great potential tohelp researchers gain new insights into disease processes at the organ,cellular and molecular level.

The availability of MPI scanners for preclinical researchstudies is a prerequisite for establishing the value of this promising newtechnology for patient care, states Philips' director of communications SteveKlink.

"For the development and commercialization of preclinicalMPI scanners, we intend to team up with Bruker BioSpin, a company with a set ofcompetencies that is complementary to ours," Klink says. "The highly sensitivevisualization of functional characteristics in vivo at high temporal resolution of MPI bears greatpotential for small animal imaging, especially when combined with high spatialresolution morphological MRI where Bruker BioSpin is recognized as a leader."

To develop a new scanner technology for use on humans is notonly a technical problem, but also requires intensive studies for possibleapplications of such technology and development of new contrast agents, whichcan only be done with a preclinical system, adds Bruker BioSpin'scommunications director Dr. Thorsten Thiel.

Klink explains how MPI works: The iron-oxide nanoparticlesare responsive to external magnetic fields. As a result, even a weakoscillating magnetic field generated by the MPI scanner will cause them tomagnetize. While doing so, they emit a small but detectable electromagneticsignal that can be picked up by a receiving antenna. It is this signal that ismeasured by the scanner. On its own, however, this signal would only detect thepresence of magnetic nanoparticles in the imaging area, not their exactlocation within that area.

To do this, the imaging area is saturated with a strongstatic magnetic field that forces the nanoparticles to magnetize in a fixeddirection, thus rendering these particles silent to MPI. Then a single pointwithin the imaging area is created where the static magnetic field strengthfalls to zero (a so-called "Field Free Point"). At this point, thenanoparticles remain free to oscillate in response to the applied oscillatingmagnetic field. The amplitude of the signal picked up by the receiving antennais then a measure of the nanoparticle concentration only at the Field FreePoint and nowhere else. To create the entire image, all that needs to be doneis to move the Field Free Point until every point in the imaging area has beenscanned.

The technology has been used in a preclinical study togenerate real-time images of arterial blood flow and volumetric heart motion.In this study, the first in vivo, 3Dreal-time MPI scans were presented revealing details of a beating mouse heartusing a clinically approved concentration of a commercially available MRIcontrast agent, achieving a spatial resolution sufficient to resolve all theheart chambers. The planned preclinical product will be specified toaccommodate larger animals.

"We are convinced that MPI is an exciting technology thatwill allow scientists to explore an extensive range of new imaging capabilitiesand applications in preclinical research," Klink says. "Depending on the exactcontrast agents that will be used, theoretically, both molecular and anatomicalinformation can be obtained with an MPI/MRI scanner."

"We are very pleased about this collaboration with Philipson this exciting technology. Magnetic particle imaging is expected to allowscientists to explore an extensive range of new imaging capabilities andapplications in preclinical research," adds Wulf-Ingo Jung, managing directorof Bruker BioSpin MRI GmbH.