Erwin L. Hahn Institute for MRI

Research

There are currently seven research groups working at the Erwin L. Hahn Institute for MR Imaging. The central research interests and expertise of these groups cover very different areas of specialization and application, which creates opportunities for both complementary and synergistic collaboration. Thanks to the close interdisciplinary and international cooperation between the research groups, the ELH is able to investigate technical, methodological and medical questions relating to 7 Tesla UHF MRI across all the disciplines – a unique feature that helps to underpin the Institute’s position as one of the leading centres for UHF MRI research and application in the world. The research priorities of the different groups at the ELH over the past two years are outlined in the following sections.

Radio-frequency technology

Research in the group of Prof. Dr. Mark Ladd (DKFZ Heidelberg) focuses on the development of methods and technologies to make 7 Tesla examination possible in all parts of the human body, including the torso. The research concentrates primarily on the following:

  • Radio frequency (RF) excitation antennas with several independent elements, 
  • numerical simulation in inhomogeneous models of the human body to explore the distribution of the transmitting magnetic field (B1) as well as the associated heating of the body (SAR), including in the presence of electrically conducting implants, and
  • radio-frequency excitation strategies for more even distribution of the B1 field or spatially selective excitation/saturation.

The group is working with a number of other locations in the framework of a DFG-funded project (Deutsche Ultrahochfeld-Bildgebung/German Ultrahigh Field Imaging, GUFI) on quality assurance standards for MR imaging using very powerful magnetic fields. 

Work is also underway as part of a collaboration between the ELH in Essen, the DKFZ in Heidelberg and the Institute of Microwave and RF Technology in Duisburg (Prof. Solbach) on research and development of a 32-channel RF transmit system. This system is the only one of its kind in the world, as 7T UHF MRI systems to date have been equipped with a maximum of 16 independent RF transmit channels. The research is financed by the European Research Council through its “MRexcite” ERC Advanced Grant. 

Radio-frequency antennas and diagnostic applications

The High Field and Hybrid MR Imaging research group led by Prof. Dr. Harald Quick also focuses on the development of new methods and new multi-channel RF transmit/receive coils for UHF MRI imaging. Here the RF coils are simulated, developed and assembled. The aim of the group’s work is to fully exploit the high SNR of UHF MRI and achieve the highest possible spatial detail resolution for various applications in clinical diagnosis. Another main research interest concerns safe application of MRI also for patients with passive and active implants. Comparative clinical studies are undertaken to assess the advantages and disadvantages of 7 Tesla UHF MRI in relation to standard MRI at 1.5 and 3.0 Tesla. The research groups within the Erwin L. Hahn Institute with a chiefly neurological focus benefit through this process from new RF coils and methods. With new RF coils it is possible to further improve high-resolution oncological MR imaging and help to extend its application to other parts of the body (thorax, abdomen, pelvis).

Cancer diagnosis

This is the field of Dr. Tom Scheenen’s research group, which specializes in the refinement of MR imaging and MR spectroscopy for oncology with the aim of rapidly translating innovation into clinically relevant applications. Research work in this group extends from the development of new RF coil technology and imaging sequences for 7 Tesla UHF MRI, through investigation of new in-vivo biomarkers to assess the aggressiveness of cancer, prostate cancer in particular, to large-scale patient studies. The latter serve clinical validation of multi-parameter MR imaging for prostate cancer management. Based on the excellent research results on prostate diagnosis, the scope for cancer diagnosis using 7 Tesla UHF MRI is to be extended in future to include visualization of the smallest metastases of different types of tumour. 

Neuroimaging

The other research groups at the ELH work chiefly in the area of functional MRI (fMRI), the technology that makes it possible to visualize brain activity.

The research group led by Prof. Dr. David Norris has succeeded in achieving isotropic resolution down to 1 mm3 in fMRI. As a result, it is now possible for the first time to not only examine the activity on a level of the brain regions but to also observe activation as a function of depth in the grey matter. Histologically, there are a total of six levels within the grey matter that have different functions and connectivity patterns. Thanks to the high spatial resolution achieved in fMRI, interaction between brain regions and the individual layers can now be investigated in greater detail.

David Norris’s group has further implemented techniques for 7 Tesla MRI spectroscopy which permit detection of gamma amino butyric acid (GABA), the most important inhibitory neurotransmitter in the brain. The researchers have shown the tonal level of GABA in brain regions that are associated with memory formation to be an indicator for memory performance.

Cognitive psychology

he research group of Prof. Dr. Matthias Brand explores neural correlates of cognitive and emotional processes using fMRI, investigating in particular the neural mechanisms involved in decision making and their interaction with control processes. Research topics include the ability to influence decisions by means of emotional processing, human-technology interaction, and the neurobiological and neuropsychological principles of addictive behaviours, such as internet or shopping addiction. The main focus in this area is on brain responses to confrontation with stimuli associated with addiction and their significance for subjectively perceived craving. Because of its high magnetic field strength and good spatial resolution, UHF MRI at the Erwin L. Hahn Institute also permits internal differentiation in individual brain structures, such as the amygdala or the ventral striatum. For the fMRI research outlined, the 7 Tesla MRI system furthermore allows visualization of activation in small structures, which is not possible or only with great difficulty in 1.5 or 3.0 Tesla MRI

Function of the cerebellum

Another area that can only be investigated with the aid of 7 Tesla UHF MRI is the cerebellar nuclei located deep in the cerebellum. The cerebellum is attracting increasing interest in neuroscience because, contrary to previous belief, it not only supports motor processes and learning but also plays a role as a modulator in very many areas, including certain cognitive functions, emotional processing, and pain. The Experimental Neurology group led by Prof. Dr. Timmann-Braun uses UHF MRI for structural visualization of the cerebellar nuclei in healthy subjects and the changes they undergo in patients with certain conditions affecting the cerebellum (known as ataxias), as well as for functional MRI studies. Associative learning processes are a main focus of present studies being undertaken as part of a research unit funded by the German Research Foundation (DFG). The capacity to unlearn (extinction) plays a major role in anxiety disorders. In this area, Prof. Timmann-Braun uses UHF MRI to test the hypothesis that the cerebellum plays an important role in the neuronal network involved in extinction.

Pain research

The research group of Prof. Dr. Ulrike Bingel uses high-resolution MR imaging of the brainstem and spinal column to investigate the connections between certain subcortical areas and pain processing in the spinal column. The aim of the research is to learn more about the intersection between pain processing in the central nervous system and cognitive neuroscience. In order to do this, the researchers investigate the mechanisms of individual sensitivity to pain, susceptibility to chronification of pain, and the capacity for pain modulation under certain contextual conditions. Methodologically, they use structural and functional MRI in combination with pharmacological and psychophysical approaches. The studies are conducted on healthy subjects and groups of patients suffering from chronic pain or neurological conditions such as Parkinson’s disease. Current studies aim to advance understanding of interindividual differences in response to placebo effects in pharmacological treatments in order to further improve therapy management.