RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of streptavidin (SA)-DTPA-Gd after intraperitoneal and intravenous administration for tumor enhancement in targeted magnetic resonance imaging (MRI).</p><p><b>METHODS</b>Biotinylated monoclonal antibody CL3 (600 microg) was intravenously injected into 12 BALB/c nude mice with subcutaneous inoculation of LoVo cells, followed by administration of 80 microg avidin as the chaser 24 h later and then SA-DTPA-Gd was injected intravenously or intraperitoneally after another 30 min. MRI was performed before and 20, 60 min and 3, 6, 9, 12 h after the injection of the contrast agents, and the MR signal intensity of the tumor and liver was determined.</p><p><b>RESULT</b>The maximum enhancement ratio of the tumor was 70.2% in the intravenous injection group and 46.4% in the intraperitoneal group, showing significant difference between them. The maximal enhancement rate of the liver was 23.7% in the intraperitoneal group and 20.4% in the intravenous group, showing no significant difference.</p><p><b>CONCLUSION</b>MR targeted imaging with biotinylated monoclonal antibody CL3 and SA-DTPA-Gd has specific enhancement effect. Higher blood level of SA-DTPA-Gd in the intravenous group facilitates the tumor enhancement in MRI in subcutaneous tumor model.</p>