Evaluation of glass microspheres for intra-arterial radiotherapy in animal kidneys

Abstract

Purpose: To evaluate the histologic distribution of nonradioactive microspheres when intra-arterially infused into normal kidneys, and to evaluate the histologic changes after the infusion. Materials and Methods: The glass microspheres were SiO 2 microspheres with a smooth spherical shape measuring 20–30 micrometers in diameter with a specific gravity of 2.2 g/cm 3. After the microspheres were mixed with contrast medium, they were infused into the renal artery. Twelve rabbits were sacrificed at 1 day, 3 days, 1 week, and 8 weeks after the treatment, respectively. The specimen was fixed with 10% buffered formalin, specially embedded in methyl methacrylate (MMA) resin and was stained by hematoxylin-eosin. The distribution of the microspheres in the kidney was analyzed microscopically, and histologic changes were also evaluated. Results: The microspheres were found in arterioles whose diameters were about 20–30 micrometers, within normal kidneys. All vessels containing microspheres were confined to arterioles or arteries. No migration of microspheres was detected in the normal lung or the contralateral kidney. Severe ischemic changes were observed in kidneys, developing within 8 weeks of the infusion. Conclusion: Glass microspheres seemed to be a useful embolic material for intra-arterial radiation therapy.