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Division of Medical Physics in Radiology

Prof. Dr. sc. techn. Mark E. Ladd

Conventional gadolinium contrast-enhanced
MRI (left) together with a pH-weighted amide
CEST image (right) of a brain tumor patient
(glioblastoma) obtained with the 7 Tesla MRI
system. Chemical Exchange Saturation Transfer
(CEST) imaging allows the detection of amide
protons in protein backbones by indirect
modulation of the water signal. The endogenous
amide CEST contrast delineates the tumor region
very similar to the conventional image without
the need of an intravenously applied contrast
agent (Zaiss M. & Bachert P. (2013). Chemical
exchange saturation transfer (CEST) and MR
Z-spectroscopy in vivo: a review of theoretical
approaches and methods. Physics in Medicine
and Biology, 58, R221–R269).
Vergrößerte Ansicht Conventional gadolinium contrast-enhanced MRI (left) together with a pH-weighted amide CEST image (right) of a brain tumor patient (glioblastoma) obtained with the 7 Tesla MRI system. Chemical Exchange Saturation Transfer (CEST) imaging allows the detection of amide protons in protein backbones by indirect modulation of the water signal. The endogenous amide CEST contrast delineates the tumor region very similar to the conventional image without the need of an intravenously applied contrast agent (Zaiss M. & Bachert P. (2013). Chemical exchange saturation transfer (CEST) and MR Z-spectroscopy in vivo: a review of theoretical approaches and methods. Physics in Medicine and Biology, 58, R221–R269).

The Division of Medical Physics in Radiology plays a pivotal role in all imaging-based diagnostic and therapeutic procedures, developing new and optimizing existing methods. To improve and individualize cancer patient treatment, the acquisition of quantitative biomedical information about the metabolic, physiologic, and functional parameters of tumors and metastases is essential. We are, for example, expanding the diagnostic value of magnetic resonance imaging (MRI) by using a very powerful magnetic fi eld (7 Tesla) to enable the depiction of the distribution of sodium (Na-23), oxygen (O-17), and even potassium (K-39) in vivo. Through the extension of MRI diffusion measurement techniques, we are able to gain additional information about cellular membranes and incoherent capillary fl ow in tumor tissue. Computed tomography (CT) techniques that allow dramatic reductions in radiation dose to enable CT fl uoroscopy or that reduce motion-induced artifacts are also in the focus of our work. Furthermore, we are developing noninvasive diagnostic methods for the in vivo detection and functional characterization of metastases on the micro-morphological level. New targeted contrast agent designs are being pursued that allow the attachment of different imaging tags in a modular manner. These concepts permit the use of multiple biophysical techniques (MRI, CT, Positron Emission Tomography (PET), optical imaging) to monitor molecular processes in a relevant pharmacological context.

The Division will continue its role as a center of excellence in oncologic imaging methodology and expand and strengthen its support of the clinical divisions. Novel acquisition and reconstruction strategies are in development for multiple tomographic modalities that are targeted toward improving diagnostics and therapy monitoring, and molecular imaging methodologies are being pursued with a focus on metastatic processes, including the further development of multimodal small-animal tomographic systems. Major objectives for the future involve research projects with the 7 Tesla system and the newly established hybrid MRI-PET system. For example, we have a major effort underway to overcome the technical challenges of imaging the human torso at 7 Tesla. Success would allow us to translate techniques from the brain and take advantage of the enhanced sensitivity of the high magnetic fi eld in organs like the liver, kidneys, and prostate. As part of a concerted initiative across DKFZ divisions, we will be applying a multitude of imaging techniques to improve the characterization of prostate cancer and thus avoid unnecessary therapy.

Selected Publications

Kuder T.A. et al. (2013). Diffusion pore imaging by hyperpolarized xenon-129 nuclear magnetic resonance. Physical Review Letters, 111, 028101.

Umathum R. et al. (2013). In vivo 39K MR imaging of human muscle and brain. Radiology, 269, 569–576.

Flach B. et al. (2013). Low dose tomographic fluoroscopy: 4D intervention guidance with running prior. Medical Physics, 40, 101909.

Mühlhausen U. et al. (2011). A novel PET tracer for the imaging of αvβ3 and αvβ5 integrins in experimental breast cancer bone metastases. Contrast Media & Molecular Imaging, 6, 413–420.

last update: 10/09/2015 back to top