Next Generation Chemical Exchange saturation transfer MRI

• Applicant: Professor Dr. Moritz Zaiss
• Subject Area: Medical Physics, Biomedical Technology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442377885

Magnetic resonance imaging (MRI) is a noninvasive imaging technique that combines the best soft tissue contrast with high spatial resolution. It is therefore the preferred method for many anatomical questions. Additional to the excellent properties in morphological imaging of soft tissues MRI has also a high sensitivity for functional processes and will be used for example for imaging of perfusion and neuronal activation. However, many diseases are directly connected to cellular function and characterized by metabolic processes. With in-vivo spectroscopy magnetic resonance is also able to investigate certain metabolic processes but this technique suffer from a rather low sensitivity leading to low spatial resolution and partial volume problems. CEST MRI uses the chemical exchange saturation transfer from metabolite molecules to tissue water with its high concentration and is able to enhance the metabolite sensitivity by factors of up to thousand or even more. However, for a broad practical application of CEST MRI some challenges still exist. These are long scanning times for image series used in CEST quantification, basic technical limitations for RF saturation, optimal molecular saturation for information encoding and a complex post-processing for quantitative extraction of molecular information. This projects aims to combine new advanced methods in MR research and recent mathematical approaches to achieve a major step forward for fast and quantitative imaging of metabolic conditions. There are two major research areas, on the one hand the fundamental reduction of scanning time and on the other hand the improvement of the specific molecular saturation for sensitivity enhancement at whole body systems. For the reduction of the scanning time a combination of parallel imaging with subsampling and com-pressed sensing methods for reconstruction will be explored. Such a combination seems to be particular successful for image series with inherent correlation as it is expected for CEST spectra used for quantification. It is aimed to accelerate data acquisition by a factor of ten or even more with similar image quality to conventional scanning. In a further step the integration of quantitative analysis into reconstruction is explored. Optimal control was recently used to design RF slice selective excitation and refocusing pulses complying technical limitations of whole body systems with much better properties than state of the art pulses. This method should now be used for the first time to optimize spectral selective saturation of different metabolite protons considering exchange rate, resonance offset and spill-over effects. If all aims are successfully achieved the proposal can make a decisive contribution to the development of MRI to unique morphological, functional and metabolic imaging modality and prepare the way of MRI for a broader future clinical application in metabolic biomarker imaging and precision medicine.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partners: Professor Dr. Kristian Bredies; Professor Dr. Rudolf Stollberger