MR imaging of nude mouse bearing human hepatocellular carcinoma by using two-step pretargeting strategy
- VernacularTitle:二步法预定位技术对荷人肝癌裸鼠模型的MR免疫成像研究
- Author:
Yikai XU
;
Xian LIU
;
Jing YE
- Publication Type:Journal Article
- Keywords:
Biotinylation;
Magnetic resonance imaging;
Antibodies, monoclonal
- From:
Chinese Journal of Radiology
2001;0(04):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To improve the sensitivity of MR molecular imaging by using targeting and magnifying effects of biotin-avidin system (BAS). Methods After preparing biotinylated monoclonal antibody HAb18, the number of biotin molecules coupled to each antibody and the binding capacity of biotinylated antibody were determined. Two-step pretargeting tumor imaging was first achieved by intravenously injecting biotinylated monoclonal antibody HAb18 into 8 BALB/c nude mice bearing QGY-7723 tumor cells line. 24 h later, Gd-DTAP-streptavidin (Gd-DTPA-SA) was injected. Gd-DTPA-HAb18 and Gd-DTPA were respectively injected intravenously into the other 12 tumor-bearing mice as contrast groups. MR imaging was performed before and 10, 30, 60 min, 3, 6, 12, 24 h, and 48 h after injection of MR contrast agents. All images were obtained using SE T_1-weighted imaging sequence. After MR imaging, enhancement time course of three different groups was determined by using enhancement data measured in the region of interest in the tumor. Enhancement ratio and contrast-to-noise of tumor were also calculated. Results The average number of biotin conjugated with each monoclonal antibody molecular was 20. And the immunoactivity of biotinylated antibody was 91%. In two-step pretargeting strategy, SI of tumor increased slowly and reached the maximum value at 6 h after injection of Gd-DTPA-SA, enhancement ratio and CNR of tumor had significant difference with other two enhancement methods. The enhancing effect of tumor was still perceptible even after 48 h. When using Gd-DTPA-HAb18, the tumor enhancement pattern was slow and slight. Even at 24 h after injection of Gd-DTPA-HAb18, enhancement ratio of tumor was 13.5%. After Gd-DTPA was injected, signal intensity of tumor increased rapidly, and reached the maximum value at 30 min after injection of Gd-DTPA, and then decreased rapidly. Conclusion Two-step pretargeting strategy based on BAS has specific and signal magnifying effects in tumor MR imaging. It can increase the number of gadolinium that bind to the tumor and provide new approach to MR molecular imaging.
