Prof. Dr.-Ing. Tobias Knopp

Universitätsklinikum Hamburg-Eppendorf (UKE)
Sektion für Biomedizinische Bildgebung
Lottestraße 55
2ter Stock, Raum 209
22529 Hamburg
- Postanschrift -

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

Tel.: 040 / 7410 56794
Fax: 040 / 7410 45811
E-Mail: t.knopp(at)
E-Mail: tobias.knopp(at)



  • Head of the Institute for Biomedical Imaging
  • Editor-in-chief of the International Journal on Magnetic Particle Imaging (IJMPI)

Consulting Hours

  • On appointment

Research Interests

  • Tomographic Imaging
  • Image Reconstruction
  • Signal- and Image Processing
  • Magnetic Particle Imaging

Curriculum Vitae

Tobias Knopp received his Diplom degree in computer science in 2007 and his PhD in 2010, both from the University of Lübeck with highest distinction. For his PHD on the tomographic imaging method Magnetic Particle Imaging (MPI) he was awarded with the Klee award from the DGBMT (VDE) in 2011. From 2010 until 2011 he led the MAPIT project at the University of Lübeck and published the first scientific book on MPI. In 2011 he joined Bruker Biospin to work on the first commercially available MPI system. From 2012 until 2014 he worked at Thorlabs in the field of Optical Coherence Tomography (OCT) as a software developer. In 2014 he has been appointed as Professor for experimental Biomedical Imaging at the University Medical Center Hamburg-Eppendorf and the Hamburg University of Technology.


Title: Dynamic Multi-Colored Magnetic Particle Imaging of a Healthy Mouse using multiple Tracers. <em>World Molecular Imaging Congress (WMIC) 2018</em>
Written by: P. Szwargulski, P. Ludewig, M. Graeser, M. Möddel, N. Gdaniec, K.M. Krishnan, H. Ittrich, G. Adam, T. Magnus, T. Knopp
in: <em>World Molecular Imaging Congress (WMIC)</em>. Sep (2018).
Volume: Number:
on pages:
how published:

Note: inproceedings

Abstract: Purpose: Magnetic Particle Imaging is a tracer based imaging modality that is highly sensitive, quantitative, and allows for 3D imaging in real-time [1]. Several iron-oxid based tracer materials with different coatings are available, which – depending on their coating – distribute differently in the body after intravenous injection. Rahmer et al. [2] introduced a multi-spectral reconstruction approach making it possible to distinguish different tracers and colorize them differently in an image. Recently the first multi-colored in-vivo MPI images have been presented [3] using a field-free point scanner, where the lungs and the liver were measured simultaneously with two different tracers. In this work dynamic colored MPI in-vivo images are presented. We will show that the vascular system can be visualized with a blood-pool tracer while a second tracer allows imaging the accumulation in the liver, the kidney, and the spleen. Material and Methods: For the experiment a preclinical field-free point MPI scanner (Bruker, Ettlingen) was used. A 3D Lissajous-type imaging sequence with 12 mT drive-field strength and 2 T/m selection-field gradient was applied. A custom receive chain with a gradiometric receive coil with 72 mm bore size was used [4]. The experiments were carried out using a heathy mouse model. A tube was prepared with one bolus of 15 ?L Perimag (5.6 mg/ml) followed by a second bolus of 15 ?L LS-008 (5.14 mg/ml). The boli were applied within a single intravascular injection. The imaging area was focused on the heart and the liver to visualize the distinction of the tracers. Since the blood half-live of Perimag and LS-008 are strongly different, it is expected that Perimag will accumulate after few minutes in the liver while LS-008 will stay in the blood pool. The entire measurement consisted of 100000 frames with a repetition time of 21.54 ms. The bolus injection started after 2000 frames. For improved signal-to-noise ratio, 200-fold block-averaging was applied leading to an effective repetition time of 4.3 s. Results: The results show at the beginning the injection of both tracers individually. After mixing of both tracers in the heart the density of Perimag in the circulating blood is degraded since it is accumulated in the liver and further organs. Already after 7.5 min an essential part of the tracer was observed in the liver and the spleen. An accumulation in the kidney could be observed after 10.0 min. The long circulating tracer LS-008 stays in the bloodstream and in turn allows imaging the vascular tree and blood perfusion during the Perimag accumulation. Conclusion and Outlook: Multi-colored MPI enables the simultaneous visualization of different tracer in-vivo with high spectral resolution. In the presented work the arrival and saturation times could be derived from the reconstructed dynamic multi-spectral MPI data. It was shown that different organs could be differentiated spatially and also spectrally. However, further analysis on signal leakage between both tracer materials and the changing of particle behavior in-vivo is necessary. With functionalized tracers multi-colored MPI could potentially enable imaging of tracer binding to cancer tissue in real-time while a secondary tracer can monitor the organ perfusion.