| The field of molecular imaging is an exciting fusion of many different scientific fields, including imaging technologies, molecular biology, and chemistry that are providing major new insights and advances into today's life-threatening diseases. Magnetic Resonance Imaging (MRI) is undoubtedly the imaging modality of choice for in vivo applications. The main limitation associated with this technique is the lack of sufficient sensitivity to detect analyte concentrations below the sub-micromolar range. New approaches are thus necessary to bring MRI in close competition with optical and nuclear methods for molecular imaging. Clinical MR imaging largely involves detection of protons so, in this work, we are focusing on improving the acquired clinical information by altering contrast in water proton images through the use of contrast agents. Paramagnetic complexes based on chemical exchange saturation transfer (PARACEST) offers a new mechanism for MRI contrast that could potentially improve sensitivity. The first part of this dissertation shows the potential of a PARACEST agent in sensing oxidative stress while the second part explores the possibility of providing tissue contrast by creating a hyperpolarized spin state in water protons using metal-ligand systems previously used for PARACEST. In the latter part, it is our goal to further enhance water proton intensity by hyperpolarizing an appropriate complex bearing a long T1 metal center and transferring that polarization to water protons, thus creating a new MRI mechanism fusing hyperpolarization and CEST imaging. |
