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Transfer von Parawasserstoff induzierter Kernspinpolarisation auf 13C zur Empfindlichkeitssteigerung in der Magnetresonanztomographie

Antragstellerin Dr. Ute Bommerich
Fachliche Zuordnung Analytische Chemie
Förderung Förderung von 2009 bis 2015
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 90607288
 
Erstellungsjahr 2014

Zusammenfassung der Projektergebnisse

Bernarding group. The first focus was the implementation and optimization of the technical environment and the workflows for PHIP NMR. A mobile para-hydrogen-enriching unit was built allowing PHIP in different labs. A new 300 MHz NMR spectrometer (Bruker WB 300) was installed and, in close cooperation with the Bommerich group the protocols for PHIP (1H and hetero nuclei) were developed and optimized for the 300 MHz spectrometer and the experimental MR tomograph located at LIN (Bruker, 4.7T). In cooperation with the Bommerich group the Bernarding group simulated, optimized and built a 1H/13C surface coil. To test 13C PHIP image protocols an angiography phantom was developed. The second focus was the development of novel hyperpolarized 19F labeled molecules to serve as background-free detection of biomarkers. In close cooperation with the Bommerich group that had so far published the only existing para-hydrogen hyperpolarized 19F spectrum 3-fluorstyrene was successfully hyperpolarized which led to the first hyperpolarized 19F image while the thermally polarized image did not allow to detect any 19F signal. Signal enhancement (under ALTADENA condition) for 19F was highest in the meta position. To move towards biocompatible substances 19F-labeled semi-fluorinated carbons (PFC) were studied as some PFC are certified already since a long time for medical use. Surprisingly, the signal enhancement with a factor of about 20 was highest when 19F was not vicinal to the position of the hydrogenation site but on the terminal CF3 group. Relaxation times were comparable for all positions leaving the transfer mechanism of the hyperpolarization from 1H to 19F over 8-9 bonds an open question to be solved in the next period of the project. In cooperation with the Bommerich group a fluorinated substance could be hyperpolarized on 19F that has strong structural similarities to biomarkers used for Alzheimer imaging (see below). In the next study PHIP was applied to hyperpolarize ethanol which until now was not achieved as the unsaturated precursor of ethanol exhibits a keto-enol-tautomerism rendering the molecular configuration instable. In a new approach the enol form was stabilized in ester configuration followed by hydrogenation and subsequent hydrolysis of the according carbon acid which finally yielded hyperpolarized ethanol for the first time. This working package was done in close cooperation with the Bommerich group. In the last part PHIP was explored as a means to increase the SNR in low or ultra-low fields. PHIP allowed to detect both 1H and 19F resonances simultaneously with only one scan in Ethyl 4,4,4-trifluorcrotonate which was reported before only by Hamans et al. ( 2011). For increasing the sensitivity for simultaneous broadband detection of several hetero nuclei in varying low fields (earth field and less) a SQUID-based detection unit was constructed by the Bernarding WG and realized with support of the Physikalisch-Technische Bundesanstalt, Berlin. Due to delivery problems of the dewar the time line of this sub-project was delayed but the detection, polarization, and fieldcompensation unit were realized. Extensive noise measurements within and outside magnetically and electromagnetically shielded rooms showed that operating a SQUID in environments outside a shielded room is possible by using a 0.2 mm thick aluminum foil but at the cost of a severely decreased signal-tonoise ratio.

Projektbezogene Publikationen (Auswahl)

 
 

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