Tc-99m-labeled polystyrene and cellulose macromolecules: agents for gastrointestinal scintigraphy

Several polystyrene resin and cellulose derivatives were evaluated for potential use as Tc-99m-labeled particulate markers for studies of gastric emptying and intestinal transit time, and for imaging segments of the gastrointestinal tract. The polyamine and quaternary ammonium polystyrene resins bound pertechnetate (Tc--99m) anions effectively; the labeling efficiency was over 95% at physiological pH values. In-vitro stability studies of Tc-99m-labeled resins in simulated gastric and intestinal fluid showed that less than 8% of the label was released after 24 h. The commercial resins dowex 2-XB, AG 1-X2, and Bio-Rex 9, labeled with Tc-99m, may be used as particulate markers of solid digesta in external scintigraphic studies of the gastrointestinal tract. Dowex 2-X8 showed relatively more extensive uptake of pertechnetate and greater stability in simulated gastric and intestinal fluids.