Hepatic artery injection of Yttrium-90-lipiodol: biodistribution in rats with hepatoma.

In this study, we analyzed the biodistribution of 90 Y-lipiodol in rats with liver tumors (hepatoma) following hepatic arterial injection. Methods : Sixteen male Sprague-Dawley rats with liver tumors were killed at 1, 24, 48 and 72 hr (four rats at each time) after injection of approximately 0.1 mCi 90 Y-lipiodol through the hepatic artery, respectively. Samples of tumor, liver, spleen, skeletal muscle, lung, kidney, bone, whole blood and testis were obtained and counted to calculate the tissue concentrations (%ID/g). Results : We found that the radioactivity in the liver tumor was high at 1 and 24 hr and then declined slowly. The biological half-time was 84.1 hr. The radioactivity in normal liver tissue was also high at 1 hr but was significantly lower than that in the tumor. The biological half-time was 38.5 hr. The ratio of tissue concentration between liver tumor and normal liver tissue (T/N ratio) was 3.03 at 1 hr and rose to 6.45 at 72 hr. The radioactivity in the lung was almost as high as in normal liver tissue at 1 hr and declined rapidly with a biological half-time of 25.6 hr. The activity levels of the kidney were moderate at 1 hr and remained at almost the same level throughout the study. A moderate concentration of radioactivity in bone was noted within the first 24 hr. The concentration, however, rose over the ensuing time. The concentration of radioactivity in skeletal muscle, spleen, testis and whole blood was quite low. Conclusion : Following hepatic arterial injection of 90 Y-lipiodol, tracer uptake in liver tumor was high and tumor retention was lengthy. Consequently, large radiation doses could be delivered to the tumor. We suggest that 90 Y-lipiodol is a potential agent in the treatment of liver malignancy.