On Tuesday 30 November, Fróði Gregersen will defend his PhD thesis "Systematic Artifacts in Current-Induced Magnetic Field Measurements by MRI".
Time: 13:30
Place: Bldg. 101, room S01 &
Zoom: https://dtudk.zoom.us/meeting/register/u5clcuyrqTIuHtKgS4nP5uZNggKia7aUvA6i
Please be aware that the PhD defence may be recorded - This will also be informed at the beginning of the PhD defence.
Supervisor: Associate Professor Lars G. Hanson
Co-Supervisor: Professor Axel Thielscher
Co-Supervisor: Professor Rong Xue
Members of assessment committee:
Professor Murat Eyüboglu, Middle East Technical University, Ankara
Associate Professor Ulrich Katscher, University of Applied Sciences, Hamburg
Associate Professor Vitaliy Zhurbenko, DTU Electrical Engineering
Chairperson: Professor Koen Van Leemput
Abstract:
Computational models of the electrical properties of the human head are increasingly used in neuroscientific research to estimate induced electric fields in non-invasive brain stimulation methods or to estimate the origin of signals measured by electro- and magnetoencephalography. However, the anatomical complexity of the human head makes accurate head modeling challenging. To create reliable head models it is important to validate their accuracy.
A good candidate for non-invasive validation is magnetic resonance current density imaging (MRCDI). MRCDI uses an MR scanner to measure magnetic fields in the brain created by currents injected through the skull. Computational head models can be validated by comparing measured and simulated magnetic fields. MRCDI of the human brain is challenging since only tiny currents can be safely applied.
The aim of this thesis was to improve MRCDI of the human brain. First, new MRCDI-optimal current injection electrodes were designed. With the new MRCDI-optimal electrodes, unwanted magnetic fields from currents flowing in the electrode leads were reduced. The second aim was to reduce the influence of physiological noise on the MRCDI measurements. This was achieved by designing faster MR imaging methods than previously used in MRCDI.