Ultra lowfield magnetic resonance imaging for the development of in vivo hyperpolarization techniques
Hyperpolarization techniques for MRI and NMR, such as ODNP (Overhauser Dynamic Nuclear Polarization) or parahydrogen based hyperpolarization, are working best at field strengths in the mT range. To investigate these techniques a NMR/MRI system operating at static magnetic fields ranging from the earth field up to a few mT was developed and built.
In order to detect a NMR signal at those low fields corresponding to Larmor frequencies in the kHz range, conventional Faraday coils are not optimal any more, since their sensitivity decreases for decreasing frequencies. Using a SQUID (Superconducting QUantum Intereference Device) based detector circumvents that issue. This detector is a broadband detector, which measures the magnetic flux directly rather than the change of the magnetic flux, making the amplitude of the NMR signal independent of the frequency. These kind of sensors are also used for the detection of MEG (MagnetoEncephaloGraphy) signals.
The boost in signal due to the hyperpolarization of the sample can be used to realize functional MRI at ultralow fields. This would be an important step in the direction of combining functional MRI at ultralow fields with MEG. The advantage of such a system would be the high temporal resolution of MEG combined with the high spatial resolution of fMRI.
The aims of the project are:
- Development and construction of a low noise NMR/MRI setup using a SQUID sensor
- Optimizing hyperpolarized contrast agents to make them suitable for first in vivo tests
- Development of in vivo hyperpolarization techniques based on ODNP
Safety simulations of RF coils for magnetic resonance imaging at 9.4 T
High static magnetic fields in magnetic resonance imaging have the advantage, that images with very high spatial and temporal resolution can be acquired. However the short wavelength of the required RF coils lead to interference effects. Inhomogeneous excitation fields that might lead to local heating are a result of this effect.
In order to guarantee safety for human subjects the performance of the home made RF coils need to be simulated to assure that the specific absorption rate limit is not exceeded.
Project leader at the Max-Planck-Institute for Biological Cybernetics
Study of physics at the university of Tübingen, Germany.
Diploma thesis on 'spectroscopy of fractional Josephson vortices'
PhD thesis at the University of Tübingen on 'activation energy of fractional vortices and spectroscopy of vortex molecules in long Josephson Junctions'.
Scientist at the physics department of the University of Tübingen, Germany.
Scientist at the physics department of the University of Berkeley, USA.
Project leader at the Max-Planck Institute for Biological Cybernetics, Tübingen, Germany