CEST-DREAM – A dynamic field-corrected metabolic CEST MRI method

• Applicant: Professor Dr. Moritz Zaiss
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 561141763

Chemical exchange saturation transfer (CEST) MRI is a metabolic imaging technique that is rich in information on several biochemically relevant contributions, such as pH, creatine, glutamate, phosphocreatine, protein/peptide content, protein structure, glucose uptake, as well as lipid content. CEST MRI has already shown promising new diagnostic insights in the imaging of tumors, stroke, and neurodegeneration, and still new CEST effects and functional correlations are discovered. However, CEST MRI sequences consist of a minutes-long series of CEST prepared scans and thus suffer from fluctuations originating from patient motion. While motion alone can be corrected, motion induces dynamic B0 and B1+- changes. As these field fluctuations occur during the CEST acquisition, false CEST effects can occur or real CEST effects can be missed, both hampering scientific discovery as well as clinically robust application. This is especially problematic at higher field strengths such as 7T, where field inhomogeneities are higher, but where CEST benefits from higher SNR and the increased spectral resolution. If the complete field information would be available for each and every CEST-prepared scan of a series, it would be possible to track changes and correct the data, leading to a next-level research tool. The aim of this proposal is to realize and validate such a new tool by combining CEST-preparation with a dual refocusing echo acquisition mode (DREAM) readout, which is able to provide CEST-prepared maps, as well as the mentioned dynamic field maps in a single acquisition step, thus within the same scan time. Such a solution will enable new discoveries in vivo due to a more accurate and more precise scientific measurement tool, and it will accelerate clinical translation as robust CEST methods can be deployed. We will validate this in amine, hydroxyl and rNOE CEST effects at 7T, which are currently least reliable. Additionally, we will investigate non-focal changes in the tumor-affected brain that are otherwise obscured by bias fields. If successful, this can improve all CEST MRI methods at different field strengths and target regions, and might further impact other magnetization-prepared contrasts.

• DFG Programme: Research Grants