Renal and Intestinal Excretion of 90Y and 166Ho After Transarterial Radioembolization of Liver Tumors

OBJECTIVE. The aim of this study was to evaluate the amount of free radioactivity in renal and intestinal excretions during the first 48 hours after transarterial radioembolization (TARE) procedures on the liver. SUBJECTS AND METHODS. Urinary, intestinal, and biliary excretions of patients who underwent TARE with three different types of microspheres were collected during a postinterventional period of 48 hours (divided into two 24-hour intervals). Radioactivity measurements were performed. The detected amounts of activity were correlated to clinical and procedural characteristics, times of excretion, and microsphere types. RESULTS. Twenty-four patients were evaluated, 10 treated with Y-90-glass, 10 with Y-90-resin, and four with Ho-166-poly-L-lactic acid (PLLA) microspheres. Activity excretion occurred in all cases. The highest total excretion proportions of the injected activities were 0.011% for Y-90-glass, 0.119% for Y-90-resin, and 0.005% for Ho-166-PLLA microspheres. Intestinal excretion was markedly less than renal excretion (p < 0.001). Excretion after TARE with Y-90-resin was statistically significantly higher than with Y-90-glass or Ho-166-PLLA microspheres (p = 0.002). For each microsphere type, the excreted activity was independent of the activity of the injected microspheres. CONCLUSION. Renal and intestinal excretion of radioactivity after TARE is low but not negligible. The radiation risk for individuals interacting with patients can be minimized if contact with urine and bile is avoided, particularly during the first 24 hours after the procedure.