Tutorial T-2: Magnetic Particle Imaging: Principles, Systems and Applications

Wednesday, March 30, 08:30 - 12:15

Presented by

Thorsten M. Buzug and Tobias Knopp (Institute of Medical Engineering, University of Lübeck)

Description

In this tutorial, a review on recent results of a novel imaging modality based on magnetic nanoparticles is given. This imaging concept, called magnetic particle imaging (MPI), falls into the category of functional imaging and, hence, the magnetic nanoparticles may serve as tracers of metabolic processes. Since the particles of choice consist of superparamagnetic iron oxide (SPIO) cores coated with biopolymers, imaging of the metabolism may be possible without any radioactive agents. These particles are subjected to an oscillating magnetic field, a so-called drive field, and, subsequently, react with a nonlinear re-magnetization. This behavior is in accordance with Langevin’s theory of paramagnetism and can be detected with appropriate receive coils. Due to the nonlinearity, the induced signal in the receive coils contains harmonics of the fundamental frequency of the drive field. These harmonics can be used to determine the nanoparticle concentration. For spatial encoding an additional magnetic gradient field, a so-called selection field, is superimposed onto the drive field such that a field-free point is established within the volume of interest. Only particles located at the field-free point contribute to the desired signal in the receive coils. Particles outside are saturated and do not further show any re-magnetization dynamics upon the excitation by the drive field. It has been shown by simulation and imaging that MPI is able to provide sub-millimeter resolution and, by simulation, a high sensitivity. Thereby, real-time applications are feasible, which has been demonstrated recently with a tracer applied in clinically accepted concentration. However, today, there are quite interesting challenges within the practical set-up of a scanning device and also in the design of new MPI nanoparticles.

About the Speakers

Thorsten M. Buzug received his Diplom-Physiker degree in 1989 and his Ph.D. in 1993 in Applied Physics both from the Christian-Albrechts-University of Kiel, Germany, where he worked in the field of signal processing applied to chaotic systems. From 1993 to 1994 he had a postdoctoral position at the German Federal Armed Forces Underwater Acoustics and Marine Geophysics Research Institute, where he worked on image acquisition and processing techniques for SONAR applications. In the end of 1994 he joined the Philips Research Laboratories Hamburg, Germany. He was the leader of the Philips Research Cluster Medical Image Processing and responsible for several projects in that field. In October 1998 he has been appointed as professor of Physics and Medical Engineering at the RheinAhrCampus Remagen. 2000-2004 he was head of the Academic Development Committee of the RheinAhrCampus Remagen. In December 2006 he became Director of the Institute of Medical Engeneering at the University of Lübeck.

Tobias Knopp was born in Lübeck, germany in 1982. He received his Dipl. Inf. in computer science in 2007 from the University of Lübeck, germany. In 2005 he wrote his student research thesis in the field of iterative reconstruction in magnetic resonance imaging (MRI). During an internship in 2005 at the Philips research laboratories, Hamburg he worked on direct k-space reconstruction for non-cartesian MRI. In 2006/2007, he wrote his diploma thesis at the Philips research laboratories, Hamburg about simultaneous estimation and correction of relaxation times in MRI. He is a research assistant at the Institute of Medical Engineering since 05/2007 and works in the field of magnetic particle imaging.

Note:Dr. Tobias Knopp will be leading the tutorial as Dr. Thorsten M. Buzug is unable to attend the conference.