Preparation and animal experiment of lymphatic system-targeted contrast agent in magnetic resonance imaging

Macromolecular conjugates of Dextran-DTPA-Gd were synthesized in two ways. One is that Dextran reacted with DTPA anhydride using DMAP as catalytic agent, the other is that Dextran reacted with DTPA using DMAPEDC ·HCl as catalytic agents. The best reaction conditions were obtained by comparing the weight content of Gd and water-solubility of the products. The product with higher content by weight of Gd (16.1%) and good water-solubility was obtained and characterized by FTIR and particle size analysis (Size distribution ranged from 100 to 150 nm, 130 nm in average). In animal experiments, the MRI of Dextran-DTPA-Gd was evaluated in comparison with the MRI of Magnevist as positive control. The signal intensities of the regional lymphatic system were qualitatively assessed by the Time-Enhancing Rate curve. The results indicated that Dextran-DTPA-Gd obviously had higher signal enhancement (maximum enhancing rate to 314%) than that of Magnevist, and can be taken up selectively by lymphatic system and showed the potential as MRI contrast agents in lymphatic system as well.