The Experimental Study Of ～(99m)Tc-EC-MN In Tumor Hypoxia Imaging

Objectives To study the biological distribution of ^99mTc-EC-MN in vivo and in vitro model of nasopharyngeal carcinoma, and to explore the clinical significance of ^99mTc-EC-MN in tumor hypoxia imaging. Methods 1.Labeling EC-MN is by means of adding the amount of 37MBq ^99mTcO₄^-and SnCl₂ to EC-MN kit. labeling efficacy is determined by the thin -layer chromatography. 2. Add ^99mTc-EC-MN into the cell strains of nasopharyngeal carcinoma under the normal and hypoxia conditions respectively, examine its difference of distribution in different period of time. 3. Inject ^99mTc-EC-MN(3.7MBq) into caudal vein of the eight nude mice and acquire planar scanning with SPECT camera after 30min, 1h, 2h, 4h, . 6h, 8h, respectively. Observe the concentration of the ^99mTc-EC-MN in tumor. 4. Divide the 12 nude mice into four groups randomly, inject ^99mTc-EC-MN 3.7MBq(0. lmL) into caudal vein, sacrified the mice after lh, 2h, 4h and 6h, respectively, take out their blood, tumor, heart, liver, spleen, lung, kidney, muscle and skeleton specimen, weigh and measure radioactivity and calculate their %ID/g. Fix the tumors which are isolated into the 10% formalin, slice and embed them in the paraffin and dewax them , immunohistochemistry study were performed on paraffin sections using CD34 McAb and VEGF McAb. Results l.The direct method of ^99mTc labeling EC-MN is easy to handle, and the labeling efficacy is high( 96%). 2.Marked difference (P<0.01) appears between the cell strains of nasopharyngeal carcinoma under the normal conditions and those under the hypoxia conditions in their respective absorption of ^99mTc-EC-MN. 3.The tumors of all the nude micedisplays positive photographical conditions. Those tumors take form half an hour after the injection and are most conspicuous four hours following the injection. However, the radioactivity of the abdomen is higher than that of the tumors. 4.99mTc-EC-MN is manifestly characterized by its tumor intimacy, its selective detention within the tumor and its high ratio of rumor/muscle and rumor/blood, with that of rumor/muscle reaching up to 2.24 at lh, 4.75 at 2h, 6.41 at 4h. 99mTc-EC-MN is rapidly cleansed from the normal tissue and is evacuated through the urinary system and the intestinal canals. 5.The results of immunohistochernistry are connected with those of radioactivity(r>0.9, p<0.01). If the contrast of the tumor's hypoxia radioactivity is quite conspicuous, the expressions of VEGF and MVD are relatively high where the ratio of T/NT is comparatively high. If the contrast of the tumor's hypoxia radioactivity is not quite conspicuous, the expressions of VEGF and MVD are relatively low where the ratio of T/NT is comparatively low. Conclusion As a 2-nitromidazole hypoxia imaging agent , 99mTc-EC-MN enjoys a fascinating prospect of exploitation.