Beta radiation and inhibition of recanalization after coil embolization of canine arteries and experimental aneurysms: how should radiation be delivered?
OBJECTIVE
Beta radiation prevents recanalization after coil embolization. We sought to determine the effects of varying coil caliber, length, activity of 32P per centimeter of coil or per volume, and spatial distribution of coils on recanalization.


METHODS
We studied the angiographic evolution of 81 canine maxillary, cervical, and vertebral arteries implanted with a variety of nonradioactive (n=29 arteries) or radioactive (n=52) devices. We compared 1- or 2-caliber 0.015 or 0.010 coils ion-implanted or not with 3 different activity levels (0.05 to 0.08, 0.06 to 0.12, 0.18 to 0.32 microCi/cm) of 32P and totaling 4, 8, and 16 cm in length for the same arterial volume. We also compared inhibition of recanalization by beta radiation delivered by stents, after coil occlusion proximal to or within the stent, with that delivered by coils placed within nonradioactive stents. We finally studied the angiographic evolution of canine lateral wall carotid aneurysms treated with 1 or 2 stents of various activity levels positioned inside the parent artery across the neck. Animals were killed at 4 and 12 weeks for macroscopic photography and pathological examination.


RESULTS
All arteries (29 of 29) occluded with nonradioactive devices were recanalized, while 49 of 52 arteries (94%) implanted with 32P devices were occluded at 4 weeks. All aneurysms treated with stents, radioactive or not, demonstrated residual filling of the sac or of channels leading to the aneurysms at follow-up angiography at 4 weeks.


CONCLUSIONS
The recanalization process found in the canine arterial occlusion model is minimally affected by coil caliber, number, and length or packing density. Beta radiation reliably inhibits this process, but thrombosis is an essential condition for the efficacy of a radioactive coil strategy.
Raymond
Jean
J
Department of Radiology, Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montreal, Quebec, Canada H2L 4M1. dr_jean_raymond@hotmail.com
Leblanc
Philippe
P
Morel
François
F
Salazkin
Igor
I
Gevry
Guylaine
G
Roorda
Sjoerd
S
D000783:Aneurysm / Q000473:pathology / Q000517:prevention & control / Q000532:radiotherapy / Q000628:therapy*; D000818:Animals; D001157:Arterial Occlusive Diseases / Q000473:pathology / Q000532:radiotherapy / Q000628:therapy*; D001158:Arteries / Q000473:pathology / Q000528:radiation effects; D001610:Beta Particles / Q000627:therapeutic use*; D002340:Carotid Artery Diseases / Q000473:pathology / Q000517:prevention & control / Q000532:radiotherapy / Q000628:therapy*; D002341:Carotid Artery Thrombosis / Q000209:etiology; D017536:Carotid Artery, Common / Q000473:pathology / Q000528:radiation effects; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D004621:Embolization, Therapeutic / Q000295:instrumentation; D004730:Endothelium, Vascular / Q000473:pathology / Q000528:radiation effects; D004867:Equipment Design; D008438:Maxillary Artery / Q000473:pathology / Q000528:radiation effects; D009333:Neck / Q000098:blood supply; D010761:Phosphorus Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D012008:Recurrence; D016037:Single-Blind Method; D015607:Stents; D014711:Vertebral Artery / Q000473:pathology / Q000528:radiation effects
D004343:Drug Implants; D010761:Phosphorus Radioisotopes