Evaluation of Technetium-99m Labeled Dextran for The Visualization of Experimental Abscesses: A Comparative Study

99mTc-dextran was evaluated for the scintigraphic visualization of abscesses in comparison to 99mTc-HIG. Twenty-four mice were injected with 50 l turpentine in left thigh muscle. Six days later they were injected with either radio pharmaceutical (RP) containing 15 MBq 99mTc. They were sacrificed at 1, 3, 6 and 24 h and scintigrams were obtained. All the organs, the whole abscess, some blood and urine were removed, weighed and counted in a gamma counter. % injected dose/g and the concentration ratios were calculated. Blood clearance of both RP's was determined in 10 normal rabbits. The biodistribution and blood clearance studies showed similarities between the two RP's. The highest accumulation was observed in the blood, liver and kidneys with some excretion in the urine. The maximum abscess/muscle ratios were 5.37±0.67 and 5.98±1.17 at 24 h with 99mTc-dextran and 99mTc-HIG, respectively. Both RP's had prolonged blood clearance. The abscesses were well visualized with both RP's but high blood background was evident. The localization mechanism of 99mTc-dextran was thought to be due to increased capillary permeability, possible binding to proteins at the site of inflammation and difficulty in back-diffusion into blood due to high molecular weight. It is preferred to 99mTc-HIG due to lower cost and easy in-house preparation.