Head of the Magnetic Resonance Center

Prof. Dr. Klaus Scheffler
klaus.scheffler[at]tuebingen.mpg.de

 

Secretary: Tina Schröder
Phone: +49 7071 601-701
Fax: +49 7071 601-702
tina.schroeder[at]tuebingen.mpg.de

 

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High-field Magnetic Resonance - Visualizing Thinking

Modern medical diagnostics would be unthinkable without magnetic resonance imaging (MRI). In addition to traditional imaging, which reveals anatomical structures, functional MRI (fMRI) has become a valuable tool for brain research. It comes close to allowing us to watch the brain at work and has contributed considerably to the advances in human cognitive neuroscience. The special advantage of MRI is that experiments, unlike X-ray diagnostics, computer tomography (CT) and positron emission tomography (PET), can be carried out without putting any strain on the health of the person being examined. In particular, it can create outstanding images of soft tissue in the biological organism, which means, especially at high magnetic fields, that for the first time it is possible to explore human brain processes non-invasively with good spatial resolution.
 
Our primary goal is to develop new magnetic resonance techniques that are able to specifically probe the structural and biochemical composition of living tissue. This is closely linked with our interest to understand the details of magnetic resonance signal formation within a living environment, as nuclear magnetization is continuously influenced by different processes during its live time between excitation and relaxation. This is a simple, eventually computationally demanding task, since we just have to forward the tiny fluctuating magnetic fields, which are sensed by the water during its random or oriented walk through tissue, to the Bloch or similar equations. A prominent example is the detection of neuronal activation with magnetic resonance, often called functional MRI or fMRI: increased neuronal activation increases the observed magnetic resonance signal, and sometimes vice versa. This BOLD effect is the working horse of numerous applications in cognitive neurosciences, however, a detailed understanding of this effect on a microscopic or mesoscopic scale is missing.

Besides functional MRI, which measures nerve cell activity indirectly via the blood flow and blood oxygenation response, magnetic resonance is also very useful for mapping neurochemical and neurobiological brain processes directly. However, a magnetic field stronger than that of clinical instruments is necessary for these advanced measurements. To provide optimal research opportunities, two ultra high-field magnetic resonance imaging systems were acquired - an MR system with a field strength of 9.4 Tesla and a usable volume of 60 cm diameter for human studies and a 14.1 Tesla MR system for small animal studies are available. In comparison, the strength of the earth’s magnetic field in Central Europe is around 0.00005 Tesla. In addition to the two large magnets, there is a clinical 3.0 Tesla MR system available, which will be used for neuroscience applications and joint ventures.

Research on these three systems is focused on detection of neuronal activity and connectivity, as well as on the neurochemistry of the brain. This requires the development of new methods, which permit highly specific and quantitative mapping of neuronal activity and bioenergetic processes in nerve cells. Faster image acquisition and better image quality also form part of the research objective. The high magnetic field strengths provide the possibility to apply high resolution spectroscopic MR methods. These techniques permit to obtain more precise insights in the chemical processes in the brain. For example, the function of neurotransmitters such as GABA or glutamate can be revealed in greater detail. In addition to hydrogen, the most frequently used nucleus in MRI, it is possible to use the signal from other MR active elements such as carbon, oxygen, fluorine, sodium or phosphorus. Such investigations are less feasible in devices with low magnetic fields, because of the much lower sensitivity and concentration of these nuclei compared to hydrogen.

Special contrast agents can be used to increase the contrast and improve the sensitivity of the MRI method. The objective is to develop cell-specific contrast agents which are either activated in the target cell or are selectively enclosed. These new “intelligent” contrast agents can then be used with MR imaging for structural MR examinations, improved diagnostics (e.g. detection of cancer cells) or to observe cells moving in the organism.

Research Groups of the Department

Ultra High Field Magnetic Resonance
Sequences and Signals

The High-Field MR and Methodology group focuses mainly on the development of MR techniques, with emphasis on MR imaging and spectroscopy at ultra high field. In addition, the characteristics and advantages of ultra high magnetic fields are investigated. For this, we have, with a 9.4 T human MR scanner and an instrument for animal research with a field strength of 16.4 T, two of the most sophisticated tomographs worldwide.[more]

Our primary goal is to develop new magnetic resonance techniques that are able to specifically probe the structural and biochemical composition of living tissue. This is closely linked with our interest to understand the details of magnetic resonance signal formation within a living environment, as nuclear magnetization is continuously influenced by different processes during its live time between excitation and relaxation.[more]                                               

MRI RF Hardware
Clinical Studies at Ultra-High Magnetic Field strengths (UHF)



The focus in the RF lab is to develop transmit arrays that provides control over the B1+ field for RF shimming and dynamic parallel transmission methods. The transmit arrays are combined with tight fitting receive arrays for increased receive sensitivity. Precise numerical simulation and safety evaluation are carried out to ensure safe in-vivo use. Travelling wave imaging and prospective motion correction using NMR field probes are being explored. Opens internal link in current window[more] 

    

We investigate the capability of UHF to unravel fine-grained tissue alterations by coupling advanced MRI methods to the latest discoveries in medical research. Methods are tailored to enhance pathology related alterations of tissue structure and function.  Through the use of high-field, high resolution quantification of MR parameters, we aim to open up new windows into the complexity of pathophysiologic processes Opens internal link in current window[more]

 

Low Field Magnetic Resonance

The Low Field MR group develops a NMR/MRI system where the detection coil is based on a Superconducting QUantum Interference Device (SQUID). With this system MR experiments can be accomplished in the earth magnetic field up to the mT range. These field strengths are optimal for polarization transfer reactions between parahydrogen and a catalyst allowing hyperpolarization of the sample. The goal of the project is to test and optimize these hyperpolarized contrast agents up to the point where in vivo studies become feasible. Opens internal link in current window [more]

Former Research Groups of the Department

Novel Contrast Agent for MRI
Multimodal Imaging using TMS and (f)MRI

Magnetic Resonance Imaging (MRI) offers a non-invasive means to map structure and function by sampling the amount, flow and environment of water protons in vivo. Contrast agents increase the intrinsic contrast generated in MR images. They are routinely used to enhance regions, tissues and cells that are magnetically similar but histologically distinct. Opens internal link in current window [more]

 

The methodological focus of our group is on the development and application of methods for high-resolution finite-element calculations to characterize the electric field induced by non-invasive brain stimulation techniques. In addition, we use the combination of transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI) in collaborations to study human motor control and multisensory integration processes. Opens internal link in current window [more]

Last updated: Sunday, 08.02.2015