Development of a dextran kit for labelling with 99mTc and its evaluation for lymphoscintigraphy

A cold dextran (molecular weight 60,000-90,000) kit has been developed by a modified procedure to produce instant preparation of 99mTc-dextran suitable for lymphoscintigraphy. The preparation was subjected to various quality control measures. Effect of pH and amount of stannous chloride as a reducing agent on the labelling efficiency using ITLC were studied. The labelled complex was separated from both the reduced pertechnetate and pertechnetate and quantified. In a series of experiments hydrolysed/reduced 99mTc was found to be less than 3.0%, whereas pertechnetate was approx. 1.0%. Biokinetics of the agent in mice and blood clearance and rate of disappearance from the site of intradermal injection of the agent in rabbits were studied. The tagged agent for imaging of the lymphatic system activated by administering Freund's complete adjuvant (FCA)/E. coli in rabbits exhibited its suitability for lymphoscintigraphy.