Kombinierte Bildgebungstechniken zur Untersuchung von Hirn-Metabolismus und -Hämodynamik während funktioneller Aktivierung bei ultra-hochfeld MRT

• Applicants: Professor Dr. Boris Keil; Professor Dr. Harald Möller
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558547427

The project focuses on advancing MRI technology to enhance the study of brain function at ultra-high magnetic field strength of 7 Tesla by addressing critical challenges in imaging neuronal activity, metabolism, and regional hemodynamics. Functional MRI (fMRI) has traditionally relied on blood oxygenation level-dependent (BOLD) signals. However, the BOLD effect has significant limitations in the quantitative and spatial interpretation of these signal changes. Alternative fMRI methods, such as arterial spin labeling (ASL) to measure local cerebral blood flow (CBF) are therefore of interest as they deliver physiologically well-defined and quantifiable parameters. Nevertheless, CBF-based fMRI still relies on hemodynmic changes to report on neuronal activity. Ideally, a more comprehensive approach would also integrate the metabolic domain, such as information on glucose, the brain's primary ''fuel``, and neurotransmitters. A novel method that provides such information is MRI-based deuterium metabolic imaging (DMI). By oral administration of ²H-labeled glucose, it allows an assessment of aerobic and/or anaerobic cerebral glucose metabolism \textit{in vivo}. The primary objective of the project is to develop RF technology to improve the fundamental acquisition scheme of ASL techniques for ultra-high-field fMRI, combined with DMI, to map local hemodynamics and regional active metabolic processes in human subjects in vivo. The project proposes integrating these MRI methods into a single measurement setup. By synchronizing the measurements for activated brain regions, metabolism, and regional hemodynamics, we aim to link glucose consumption to CBF and to separate glutamate changes resulting from synaptic neurotransmitter cycling and from those related to tricarboxylic acid (TCA) cycle activity as a proof-of-concept application. Ultra-high-field MRI at 7T is crucial for this work due to its superior signal-to-noise ratio and contrast resolution. However, implementing ASL at this field strength presents unique challenges, such as magnetic field inhomogeneities and transmit inefficiencies that compromise arterial spin labeling accuracy, as well as safety concerns due to high specific absorption rates. The project seeks to overcome these barriers by developing specialized RF technology tailored for arterial spin labeling techniques and deuterium metabolic imaging at 7T.

• DFG Programme: Research Grants