| Description |
Over the past decade, molecular imaging has emerged as a powerful tool to visualize biological processes of living subjects on the cellular or molecular level. Such techniques greatly improve our understanding of disease and drug activity. Since molecular imaging relies on exoteric imaging agents as reporters to send detectable signals towards the outside, investigation of the imaging agents is of vital importance. However, the quantification of the imaging agents is still one of the challenges facing this work. Magnetic resonance (MR) imaging has been widely used as one of the imaging modalities for molecular imaging. This dissertation focuses on the quantification of the gadolinium based contrast agent (GBCA) and the 19F contained drug and imaging agent used in MR imaging and spectroscopy. MR imaging pulse sequence, hardware and novel imaging agents have been developed to achieve more rapid and accurate quantitative methodologies for determination of imaging agents. In the first part of the dissertation, a rapid T1 and T2 mapping technique ms-DSEPI-T12 is introduced to assess in vivo dynamic T1 profile. Temporal resolution 15 sec has been achieved for the in vivo mice experiments with voxel size of 1.0×1.0×2.0 mm3. Comparing the conventional T1 mapping methods, e.g., inversion recovery, which takes several to tens of minutes, ms-DSEPI-T12 can provide much higher temporal resolution. In the second part, 19F MR spectroscopy has been collected to monitor an ocular corticosteroid, TAP, with total dosage of 9 ?mol using a rabbit model. Intravitreal and subconjunctival injections were used to deliver TAP into the rabbit eyes. The elimination half-lives of TAP in vivo and in postmortem rabbit eyes are 7.8±1.1, 17.2±2.1 Hr using intravitreal injection, and 0.5±0.1, 6.0±1.5 Hr using subconjunctival injection, which are used to investigate the possible ocular elimination pathway of TAP. In the last part, 19F MR imaging using a newly developed 19F MR imaging agent, 19FIT, was done on a 3T clinical system. For the mice experiment, conducted with voxel size 1.5×1.5×3.0 mm3 and 5 min 9 sec imaging time, relatively high SNR (ranges from 10 to 60 in heart, liver and bladder) of the 19F imaging is achieved. |
