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Synthesis of chelators for use in diagnostic imaging
Kretschmer, Jan ; Polášek, Miloslav (advisor) ; Kubíček, Vojtěch (referee) ; Hrubý, Martin (referee)
Metals play a crucial role in medicine as a part of therapeutic or diagnostic preparations. However, in the majority of cases, their properties cannot be utilized entirely in free ionic form. Organic molecules capable of chelation are used to open the full potential of the metal. The molecules are called chelators and are the core theme of this thesis. The most important function of these molecules is the chelation and coordination of the metal, but chelators can provide other important functionalities. This work, therefore, focuses on the design, synthesis, and application of such polyfunctional chelators and is divided into two parts: DO3A-Hyp This part of the thesis deals with chelators that can be used as amino acids to incorporate lanthanides into peptides. The developed chelators provide a short and rigid connection of the metal to the peptide chain. Tripeptides containing two units of such chelators with a central amino acid bearing a CF3 group were synthesized to demonstrate the capability of DO3A-Hyp building blocks. Two paramagnetic metals were combined within this tripeptide, and it was shown that such a rigid and locked system could be used for combining their magnetic susceptibility tensors. These magnetic susceptibility tensors were used for manipulation of the 19 F NMR shift of the CF3...
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Fluorine nuclear relaxation times in chelates with lanthanides
Bobrova, Yulia ; Římal, Václav (advisor) ; Wagnerová, Dita (referee)
Contrast agents containing fluorine have great prospects for magnetic resonance imaging in medicine. Low representation of fluorine in human body and the suitable magnetic properties of its nucleus 19 F, provide great sensitivity. The slow relaxation of 19 F, can be shortened by using paramagnetic complexes.In this thesis, transversal and longitudinal 19 F relaxation times of chelates with different paramagnetic lanthanides (Ce, Yb,Tm, Dy, Ho) were measured in two different magnetic fields: 4,7 and 11,7 T. Their values meet the expected assumptions. Furthermore, the values are compared with Bloch-Redfield- Wangsness theory.While Ho, Tm, and Dy reduce fluorine nuclear relaxation times to milliseconds, which is too short for MRI, relaxation rates of Ce a Yb reach approximately 100ms. Such relaxation rates can be considered as optimal for imaging methods. On the basis of our results it is possible to find suitable candidates for fluorine contrast media and optimize the measurement sequence settings in further research or in clinical use.
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