Dr.-Ing. Matthias Gräser

Universitätsklinikum Hamburg-Eppendorf (UKE)
Sektion für Biomedizinische Bildgebung
Lottestraße 55
2ter Stock, Raum 212
22529 Hamburg

Technische Universität Hamburg (TUHH)
Institut für Biomedizinische Bildgebung
Gebäude E, Raum 4.044
Am Schwarzenberg-Campus 3
21073 Hamburg

Tel.: 040 / 7410 25812
E-Mail: matthias.graeser(at)tuhh.de
E-Mail: ma.graeser(at)uke.de

Research Interests

  • Magnetic Particle Imaging
  • Low Noise Electronics
  • Inductive Sensors
  • Passive Electrical Devices

Curriculum Vitae

Matthias Gräser submitted his Dr.-Ing. thesis in january 2016 at the institute of medical engineering (IMT) at the university of Lübeck and is now working as a Research Scientist at the institute for biomedical imaging (IBI) at the technical university in Hamburg, Germany.  Here he develops concepts for Magnetic-Particle-Imaging (MPI) devices. His main aim is to improve the sensitivity of the imageing devices and improve resolution and application possibilities of MPI technology.

In 2011 Matthias Gräser started to work at the IMT as a Research Associate in the Magnetic Particle Imaging Technology (MAPIT) project. In this project he devolped the analog signal chains for a rabbit sized field free line imager. Additionally he developed a two-dimensional Magnetic-Particle-Spectrometer. This device can apply various field sequences and measure the particle response with a very high signal-to-noise ratio (SNR).

The dynamic behaviour of magnetic nanoparticles is still not fully understood. Matthias Gräser investigated the particle behaviour by modeling the particle behaviour with stochastic differential equations. With this model it is possible to simulate the impact of several particle parameters and field sequences on the particle response .

In 2010 Matthias Gräser finished his diploma at the Karlsruhe Institue of Technology (KIT). His diploma thesis investigated the nerve stimulation of magnetic fields in the range from 4 kHz to 25 kHz.

Journal Publications

[76889]
Title: Two dimensional magnetic particle spectrometry.
Written by: M. Graeser, A. von Gladiss , M. Weber, and T. M. Buzug
in: <em>Physics in Medicine and Biology</em>. (2017).
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DOI: 10.1088/1361-6560/aa5bcd
URL: http://iopscience.iop.org/10.1088/1361-6560/aa5bcd
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[www] [BibTex]

Note: article

Abstract: Abstract Magnetic particle spectrometry (MPS) is an excellent and straightforward method to determine the response of magnetic nanoparticles to an oscillatingmagnetic field. Such fields are applied in magnetic particle imaging (MPI). However,state of the art MPS devices lack the ability to excite particles in multidimensional fieldsequences that are present in MPI devices. Especially the particle behavior caused byLissajous sequences cannot be measured with only one excitation direction. This workpresents a new kind of MPS which features two excitation directions to overcome thislimitation. Both field coils can drive AC as well as DC currents and are thereby ableto emulate the field sequences for arbitrary spatial positions inside an MPI device.Since the DC currents can be switched very fast, the device can be used as systemcalibration unit and acquire system matrices in very short time. These are crucialfor MPI image reconstruction. As the signal-to-noise-ratio provided by the MPS isapproximately 1000 times higher than that of actual imaging devices, the time spaceanalysis of particle signals is more precise and easier done. Four system matrices arepresented in this paper which have been measured with the realized multidimensionalMPS. Additionally, a time space comparison of the particle signal for Lissajous, radialand spiral trajectories is given.

Conference Proceedings

[76889]
Title: Two dimensional magnetic particle spectrometry.
Written by: M. Graeser, A. von Gladiss , M. Weber, and T. M. Buzug
in: <em>Physics in Medicine and Biology</em>. (2017).
Volume: Number:
on pages:
Chapter:
Editor:
Publisher:
Series:
Address:
Edition:
ISBN:
how published:
Organization:
School:
Institution:
Type:
DOI: 10.1088/1361-6560/aa5bcd
URL: http://iopscience.iop.org/10.1088/1361-6560/aa5bcd
ARXIVID:
PMID:

[www] [BibTex]

Note: article

Abstract: Abstract Magnetic particle spectrometry (MPS) is an excellent and straightforward method to determine the response of magnetic nanoparticles to an oscillatingmagnetic field. Such fields are applied in magnetic particle imaging (MPI). However,state of the art MPS devices lack the ability to excite particles in multidimensional fieldsequences that are present in MPI devices. Especially the particle behavior caused byLissajous sequences cannot be measured with only one excitation direction. This workpresents a new kind of MPS which features two excitation directions to overcome thislimitation. Both field coils can drive AC as well as DC currents and are thereby ableto emulate the field sequences for arbitrary spatial positions inside an MPI device.Since the DC currents can be switched very fast, the device can be used as systemcalibration unit and acquire system matrices in very short time. These are crucialfor MPI image reconstruction. As the signal-to-noise-ratio provided by the MPS isapproximately 1000 times higher than that of actual imaging devices, the time spaceanalysis of particle signals is more precise and easier done. Four system matrices arepresented in this paper which have been measured with the realized multidimensionalMPS. Additionally, a time space comparison of the particle signal for Lissajous, radialand spiral trajectories is given.