The diagnostic value of ~(99m)Tc-HL91 hypoxia imaging in normalization window of gastric cancer vas-culature

Objective To evaluate the diagnostic value of ~(99m)Tc-HL91 hypoxia imaging in normali-zation window of tumor vasculature (NWTV). Methods Forty nude mice with transplanted gastric HS-746T cell line carcinoma were subjected to ~(99m)Tc-HL91 hypoxia imaging. Nude mice were randomly divided into treatment group (n=20,400 μg/each intraperitoneal injection of DC101) and control group (n = 20, injection of the same volume of saline). From 5 min to 8 h after injection the radioactivity ratio of tumor to normal tissues (T/NT) was calculated using the region of interest (ROI) technique, and the maximum ra-tio of T/NT was taken to represent the tumor hypoxia. As compared with control group at 1 to 14 days post-treatment with monoclonal antibody against vascular endothelial growth receptor 2 (DC101 ), the change in hypoxia of tumor was dynamically monitored. As compared with the hypoxia of untreated nude mice, the accurate diagnosis of NWTV was made. Results At the first day after injection of ~(99m)Tc-HL91 the tumor began to visualization at (5.46±0. 24) min in control group, and the ratio of T/NT reached the maximum at (3.24 ±0. 18) h. Whereas, those in treatment group were (30. 12±0. 11 ) min and (6. 26±0. 36) h respectively. In control group, there were no significant differences in visualization time and peak time of T/NT by 14 days. However, in the treatment group, the initial hypoxia imaging time and peak time of T/NT was decreased gradually at the second day. The visualization time [(5.32±0. 14) min vs (5.39± 0. 35 ) min, P > 0. 05] and peak time of T/NT [(3.34 ± 0. 26) h vs (3.28 ± 0. 27) h, P > 0. 05] had no difference between the treatment and the untreated groups at the 5th day. As compared with the smooth in-crease of hypoxia in control group, those in treatment group were increased wave-hkely. After DC101 treat-ment, tumor hypoxia began to drop on the day 2 (6. 23 ±0. 26), almost abolished on the day 5 (0. 24± 0. 14), and increased again by the day 8 (6. 36±0. 14). The NWTV emerged from the 2ad day to 8th day after DC101 treatment. Conclusion Hypoxia imaging of ~(99m)Tc-HL91 was a potential non-invasive tool in monitoring the hypoxia of tumor after anti-angiogenesis and in the accurate diagnosis of the NWTV. Key words: Hypoxia;  Gastric carcinoma;  Tumor vasculature;  Anti-angiogenesis