Objective   To evaluate the effects of radioimmunoimaging with

99

Tc

m

-EGFR-McAb or

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Tc

m

-CD44

-McAb or combined application of both on nude mice bearing lung adenocarcinoma.    Methods   Animal model of nude mice bearing lung adenocarcinoma was established. The direct labeling method of

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Tc

m

was applied to labeling monoclonal antibodies for EGFR and CD44

and then the properties of the labeling antibodies purified by SephadexG50 Column were identified. The radio-immuno-image as well as body distribution concerning nude mice bearing lung adenocarcinoma was studied by application of

99

Tc

m

-EGFR-McAb or

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m

-CD44-McAb alone or combined application of both.     Results   The labeling rates of

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Tc

m

for EGFR-McAb and CD44-McAb were (91.5±3.8)% and (92.3±4.1)% respectively. Specific activities of the labeled antibodies were (2.8±0.3)MBq/g and (2.9±0.5)MBq/g

respectively. The rates of radiochemical purity were (96.5±2.8)% and (96.2±3.1)%

respectively. The tumor tissue had high intake of the two labeled antibodies according to radioimmunoimaging result. The radioactivity concentration of the combined application of the two labeled antibodies was obviously higher than that of the single application. The T/NT relative values measured through ROI technique were 5.58±0.46

2.72±0.22

and 2.30±0.18

respectively. The body distribution result of the labeled antibodies and their imaging results were basically identical.     Conclusion   The optimal target and non-target ratios could be obtained by application of

99

Tc

m

-EGFR-McAb or

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Tc

m

- CD44-McAb alone in nude mice bearing lung adenocarcinoma. The target and non-target ratios could be enhanced through the combined application of the two antibodies.