Biodegradable Macromolecular MRI Contrast Agents

摘要

Magnetic resonance imaging (MRI) is a non-invasive clinical diagnostic modality. Paramagnetic metal chelates, e.g. gadolinium complexes, Gd-DTPA (DTPA: diethylenetriaminepentaacetate), Gd-DOTA (DOTA: 1,4,7,10-tetraazadodecanetetraacetic acid) and their derivatives, have been developed as contrast agents to enhance diagnostic MR images. These contrast agents are low molecular weight chelates, have a short blood circulation time and nonspecifically extravasate into normal and disease tissues. Incorporation of the paramagnetic contrast agents into macromolecules can increase both the circulation time of the agents in the blood pool and accumulation in solid tumor due to the hyperpermeability of tumor vasculature. These macromolecular paramagnetic complexes have demonstrated superior contrast enhancement in MR cardiovascular imaging and cancer imaging in the preclinical studies. Unfortunately, the clinical development of these agents is impeded by the safety concerns related to their slow elimination from the body.