The arrival of MRI scanners with ultra-high magnetic fields (≥ 7 Tesla) is expected to provide a huge leap forward in the early diagnosis of certain diseases, especially brain diseases. At these ultra-high fields, the images enjoy excellent spatial and/or temporal resolutions. However, at this field strength, the physics of MRI leads to signal losses in certain regions (typically in the temporal lobe and cerebellum) and prevents the expansion of their use in hospitals.
Several solutions are under development. One of them, simple to implement, consists in inserting in the radiofrequency antenna, which surrounds the head of the subject, "pads" containing a material with a high dielectric constant. This material, by its nature, creates currents which will modify the global distribution of the radiofrequencies coming from the transmission coil and generate a secondary radiofrequency field which corrects the problem significantly.
Itroduced in the early 1990's, this solution has since been improved in its design with new material compositions that still had some imperfections.
Researchers from the METRIC team (BAOBAB, NeuroSpin department), the Magnetic Resonance Structure and Dynamics Laboratory (UMR NIMBE, Iramis Institute of the CEA), the Fresnel Institute (Aix-Marseille University), and Multiwave Imaging have developed an alternative. Their new "recipe", made of silicon carbide, makes the pads invisible to magnetic resonance and considerably prolongs their performance, two points that were limiting for the previous generations.
Contact Joliot: