Biodistribution of Iodine-131-Iodomisonidazole and Imaging of Tumor Hypoxia in Mice bearing CT-26 Adenocarcinoma / 대한핵의학회잡지

urpose: Misonidazole is a radiosensitizer that binds in hypoxic cells. The purpose of this study was to find out the feasibility of I-131-Iodomisonidazole (IMISO) for imaging of tumor hypoxia. MATERIALS AND METHODS: Tosyl precursor was dissolved in acetonitrile and I-131-NaI was added to synthesize IMISO. Balb/c mice inoculated with CT-26 adenocarcinoma were injected with IMISO. Mice were sacrificed at 1,2,4,24 hr and % of injected dose per gram of tissue (%ID/g) was determined. For scintigraphy and MRI, mouse bearing CT-26 adenocarcinoma was administered with IMISO and imaging was performed 4 hr after. Then, mouse body was fixed and microtomized slice was placed on radiographic film for autoradiography. RESULTS: %ID/g of tumor was 1.64 (1h), 0.98 (2h), 0.85 (4h) and 0.20 (24h), respectively. At 24h, %ID/g of tumor was higher than that of all other tissues except thyroid. Tumor to muscle ratio increased with time and tumor to blood ratio also increased with time and reached 1.53 at 24 hr. On autoradiogram, tumor was well visualized as an increased activity in central hypoxic area of the tumor which corresponds to the area of high signal intensity on T2-weighted MR image. On scintigraphy, tumor uptake was visualized. CONCLUSION:: This RESULTS suggest that IMISO may have a potential for tumor hypoxia imaging in mouse model. However, further study is needed to improve it's localization in tumor tissue and to achieve acceptable images of tumor hypoxia.

Biodistribution and Scintigraphy of Iodine-131-Iododeoxyadenosine in Rats Bearing Breast Cancer / 대한핵의학회잡지

PURPOSE: I-131 labeled (2'-deoxy-2-iodo-p-D-arabinofuranosyl) adenine (IAD) may be involved in DNA synthesis during active proliferation of tumor cells. We conducted this study to find out the biodistribution of IAD and its feasibility for scintigraphic tumor imaging. MATERIALS AND METHODS: Tosyl acetyl-adenosine was dissolved in acetonitrile, and I-131-NaI was added and heated to synthesize IAD. Female Fisher 344 rats innoculated with breast tumor cells were injected witb 0.27 MBq of IAD. Rats were sacrificed at 0.5, 1, 2, 4, 24h and the % of injected dose per gram of tissue (%ID/g) was determined. For scintigraphy, rats bearing breast cancer were administered with 1.11 MBq of IAD and imaging was perforrned after 2 and 24h. Then, rat body was fixed and rnicrotomized slice was placed on radiographic film for autoradiography, RESULTS: %ID/g of tumor wa.' 0.74 (0.5h), 0.73 (1h), 0.55 (2h), 0.38 (4h), and 0.05 (24h), respectively. At 1h after injection, %ID/g of tumor was higher than that of heart (0.34), liver (0.42), spleen (0.47), kidney (0,69), muscle (0.14), bone (0.33) and intestine (0.51). However, %1D/g of tumor was lower than blood (1.06), lung (0.77), and thyroid (177.71). At 4h, %ID/g of tumor in comparison with other tissue did not change. Tumor contrast expressed by tumor to blood ratio was 0.69 and tumor to muscle ratio was 5.11 at 1h. However, these ratios did not improve through 24h. On autoradiogram and scintigraphy at 2 and 24 hour, the tumor was well visualized. CONCLUSION: This results suggest that Ial) may have a potential for tumor scintigraphy. However, further work is needed to improve localization in tumor tissue.