Novel methods for NMR

Nuclear magnetic resonance (NMR) has outstanding potential as a non-destructive technique to study a broad range of specimens. It ranges from quantum objects like single spins over macromolecules to living organisms. Although being one of the most powerful spectroscopic techniques, NMR has been suffering from its low sensitivity ever since. Ten years ago, dissolution dynamic nuclear polarization (DNP) revolutionized the field by bringing nuclear spins into a so-called hyperpolarized state, thereby increasing NMR’s sensitivity by more than four orders of magnitude. My research concentrates on the development of novel methods for NMR of hyperpolarized nuclei in combination with the numerical optimization of radiofrequency (RF) pulses by optimal control theory. Major progress of this work is a promising technique for quantitative characterization of tumor necrosis and a method for mea- surements of heteronuclear chemical shift correlations within a single scan. Ranging from theoretical and methodical concepts in RF pulse design to measurements of low concentrated metabolite diffusion coefficients up to the quantitative determination of lipid content in living insects, my research is structured in four sections: - Using optimal control pulse optimization, it is shown that virtually arbitrary off-resonance scaling of the effective J-coupling constant in heteronuclear coupled spin systems can be achieved. A new class of tailored decoupling pulses named SHOT (Scaling of Heteronuclear couplings by Optimal Tracking) is introduced. - Combining dissolution DNP with SHOT pulses effects that chemical shift correlations from hyperpolarized molecules can be accurately obtained from information contained in a single scan. - A method for measurements of apparent diffusion coefficients (ADCs) from hyperpolarized 13C-metabolites is presented. Investigations in tumor cells demonstrate that 13C ADC detection can yield sensitive information on changes in membrane permeability and subsequent cell death. In vivo measurements employing optimal control pulses demonstrate the feasibility of this technique for preclinical research. • In contrast to destructive conventional photometric and mass measurements, we demonstrate exemplarily in the European spruce bark beetle that NMR can be efficiently used to quantify and image absolute fat and water content in living insects.