Magnetic resonance characterization of gadolinium-based contrast agents

Several magnetic resonance methods have been used for characterizing gadolinium-based contrast agents in NMR Imaging in this thesis. Many Gd-based contrast agents were studied including Gd DTPA(dimethylenetriaminepentaacetic acid). The zero field splitting energies and g values of Gd complexes were obtained in frozen solutions by the EPR technique. Solvent structures of Gd-based contrast agents were studied by the ESE(Electron Spin Echo) method. Analysis of $\sp2$H-ESEEM of Gd TTHA(trimethylenetetraaminehexaacetic acid) demonstrated the existence of the second sphere water. The distance between $\sp2$H-Gd, a$\sb{\rm iso}$, and quadrupolar coupling constants were obtained by computer simulations of $\sp2$H-ESEEM of Gd complexes in frozen solutions. Water exchange times between the Gd complexes and bulk water were studied by O-17 NMR. However, it was found that the direct application of the Merbach method to the Gd-based contrast agent system showed some limitations. NMRD(Nuclear Magnetic Resonance Dispersion) studies provided useful information when combined with many other techniques. Data from NMRD simulations were well correlated with ones from EPR, ESEEM, and O-17 NMR. As a result, the combination of several techniques made NMRD analysis more reliable.In the last chapter, the results of low osmolar Gd-based contrast agents studies are described. NMRD measurements were done in water and human plasma. Some of the Gd complexes showed binding behavior with plasma proteins, especially albumin. This binding affinity seems to be varied depending on the balance between the hydrophilic and lipophilic groups in one compound