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Background and purpose Previous study showed improved therapeutic efficacy of liver tumors in rats with combined treatment of a vascular disrupting agent (VDA), Zd6126 (Zd), and antiangiogenic, thalidomide (Tha), compared to either agent alone. The present study aims to investigate whether the blood pool agent P792 further improves the evaluation of vascular permeability compared with the extracellular contrast agent Gd-DOTA in such a combined therapeutic strategy. Materials and Methods This study was approved by the institutional ethical committee for the use and care of laboratory animals. Rats with implanted liver tumors were randomized into four treatment groups: 1) Zd with Gd-DOTA (0.1mmol/kg) (n=12); 2) Zd in combination with Tha (ZdTha) with Gd-DOTA (n=12); 3) Zd with P792 (0.05mmol/kg) (n=8); 4) ZdTha with P792 (n=10). Dynamic contrast-enhanced MRI (DCE-MRI) was performed before and 4 hours (h), 2 days (d), 4d, 6d, and 12d after treatment. The tumor volume transfer constant (Ktrans) derived from DCE-MRI was quantified at each time points and compared between Zd and ZdTha treatments with the administration of Gd-DOTA and P792 respectively. Results Both Zd and ZdTha groups showed significant decreases in Ktrans at 4 h either in the administration of Gd-DOTA or P792 due to the vessel blockage and blood congestion induced by Zd. In the Gd-DOTA setting, the Ktrans between Zd and ZdTha groups was not significantly difference at each time points. However, the Ktrans in ZdTha group was significantly lower than that in Zd group at 2d (P=0.02) and 6d (P=0.01) respectively after treatment when P792 was administered. Conclusion The combined ZdTha therapy enhanced the transient reduction in tumor vessel permeability compared to the use of Zd alone. This effect can be better reflected by the application of the blood pool agent P792.