In Situ -Irradiation of a Brain Arteriovenous Malformation Model

Background and Purpose—The treatment of large brain arteriovenous malformations (BAVMs) is challenging, and embolization alone is seldom curative. The study goal is to enhance the efficacy of arteriovenous malformation embolization by adding a -emitting isotope to the embolic agent. Methods—The pig rete mirabile was used as a BAVM model. The body distribution of radioactivity was evaluated after selective rete injection of N-butyl,2-cyanoacrylate mixed with I-lipiodol in 8 animals using immediate whole body -scintigraphy. Activities within the whole rete mirabile and selected tissue samples were quantified with a gamma counter immediately after sacrifice. Two pigs were submitted to serial -scintigraphies for 6 weeks to detect delayed isotope leaching. Long-term effects of in situ irradiation were evaluated using a mixture of Re/N-butyl,2cyanoacrylate in 8 pigs. In 1 animal, autoradiography was performed to evaluate local rete mirabile distribution of the radioactivity. Seven pigs were injected with Re/glue in 1 rete mirabile and with glue only on the opposite side, and the degree of vascular occlusion of both sides was compared on histology at 2 (n 2) or 6 months (n 5). Results—There was negligible activity outside the target. Radiation caused occlusion of vessels unreached by the glue itself but in the vicinity of the radioactive source in 5 of 7 rete mirabile. Conclusions—Selective deposition of a -emitter inside a BAVM model may be achieved by current embolization techniques. The adjunct use of an isotope may increase the efficacy of embolization. (Stroke. 2005;36:2475-2478.)