Microwave Preparation of Technetium-99m Sulfur Colloid

Technetium-99m sulfur colloid ( mTc-SC) has been useful in reticuloendothelial imaging, and in particular in liver/spleen and more recently bone marrow scintigraphy. Technetium99m SC can also be employed to localize acute gastrointestinal bleeding and has been used in lung ventilation studies. The standard radiolabeling method requires a heating period in a boiling water bath. A comparison of a standard boiling technique (5 min) and a microwave technique (20 sec) for the preparation ofmTc-SC was performed. Radiochemical purity results and particle sizing data were analyzed, and a qualitative visual assessment of the change from a clear solution to an opaque one was performed. Both methods of preparation routinely yielded products with greater than 97% bound, particle sizing of greater than 82% between 0.1 p.m and 1.0 p.m, and a consistent opaque appearance of the radiopharmaceutical upon completion. Preliminary evaluation in patients demonstrated rapid blood clearance and excellent images. Microwave heating significantly reduces preparation time and yields a consistently acceptable radiopharmaceutical.