The brand new kind of leaky wave MRI antenna is an all-round expertise
Magnetic resonance tomography (MRT) at 7 Tesla is the latest generation of this technology and offers images with a significantly higher resolution than conventional devices that work with a maximum magnetic flux density of 3 Tesla. In particular, the high-frequency magnetic fields at 7 Tesla are strongly absorbed by the body tissue and therefore only poorly reach organs located inside, such as the heart or prostate.
Large range, therefore broadband and efficient
Dr. Jan Taro Svejda from the Institute for General and Theoretical Electrical Engineering (ATE) and the Center for Nanointegration (CENIDE) – together with colleagues from ITMO University St. Petersburg (Russia), Technical University Eindhoven and University Clinic of Utrecht (both in the Netherlands ) – has developed a new high-frequency coil with three decisive properties: The combination of periodic metamaterial structures directs the energy as effectively as possible into the emitted magnetic field. This avoids a strong magnetic field directly around the antenna – and thus also on the body being examined. At the same time, this leads to a greater range, as less energy is absorbed by the tissue.
The third advantage arises from the possibilities offered by this new type of leaky wave antenna: Conventional MRI antennas stimulate the resonance of hydrogen atomic nuclei in the body. Cartilage, however, could be better represented by the resonance of sodium nuclei, for example; So far, however, this would require a different antenna with the corresponding operating frequency. “On the other hand, our coil can also generate such alternative magnetic resonances,” explains Svejda. “In other words, with just one antenna, complementary MRI images can be generated that additionally highlight tissue structures containing sodium, such as cartilage.”
As a next step, the team is now working on a new version of the metamaterial structure with which the image quality in the body can be further improved.
University of Duisburg-Essen
Solomakha, G. et al. (2021) A self-adapted leaky wave antenna for ultra-high field magnetic resonance imaging with a low specific absorption rate. Nature communication. doi.org/10.1038/s41467-020-20708-w.