In Situ Beta Radiation to Prevent Recanalization After Coil Embolization of Cerebral Aneurysms

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Abstract
Background and Purpose — Endovascular treatment of cerebral aneurysms, a minimally invasive alternative to surgery, is too often followed by recanalization and recurrences. The purpose of this work was to assess if in situ beta radiation can inhibit recanalization after coil embolization. Methods — Radioactive platinum coils ( 32 P-coils) were produced by ion implantation of 32 P. A single-coil arterial occlusion model was used to compare angiographic and pathological results at 1 to 12 weeks after nonradioactive and 32 P-coil embolization of maxillary, cervical, and vertebral arteries in 26 dogs. Coils of varying activities were used and results compared to define the minimal activity required to inhibit recanalization. Similar experiments were performed in 16 porcine maxillary and lingual and 8 rabbit axillary arteries. Results of 32 P-coil embolization of bifurcation aneurysms were then compared with embolization with nonradioactive coils in 12 dogs at 3 months. Results — Nonradioactive coil embolization of canine arteries led to occlusion at 1 week, followed by recanalization at 2 weeks, which persisted at 3 months in all cases. 32 P-coils, ion-implanted with activities above 0.13 μCi/cm, led to persistent occlusion at 3 months in 80% of arteries. 32 P-coils ion-implanted with the same activity inhibited recanalization in porcine and rabbit arteries. Bifurcation aneurysms treated with 32 P-coils had better angiographic results at 3 months ( P =0.006) than aneurysms treated with nonradioactive coils. Arteries occluded were filled with fibrous tissue at 3 months. Aneurysms embolized with 32 P-coils showed more complete neointimal coverage of the neck, without recanalization, as compared with aneurysms treated with nonradioactive coils. Conclusion — In situ low-dose beta radiation inhibits recanalization after coil embolization and may improve long-term results of endovascular treatment of aneurysms.