American Journal of Neuroradiology 2009;30:1488.
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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1649
INTERVENTIONAL
Angiographic and Histologic Comparison of Experimental Aneurysms Embolized with Hydrogel Filaments
From the Departments of Neurology/Neuroscience Institute (M.K.) and Neuroradiology (M.R.M.), Paracelsus Medical University, Christian Doppler Clinic, Salzburg, Austria; Department of Radiology (D.F.K., Y.-H.D.), Mayo Clinic, Rochester, Minn; and MicroVention Terumo (J.C.S., G.M.C.), Aliso Viejo, Calif.
Please address correspondence to Monika Killer, Department of Neurology/Neuroscience Institute, Paracelsus Medical University, Christian Doppler Clinic, Ignaz Harrer Str 79, A-5020 Salzburg, Austria; e-mail: m.killer{at}salk.at
BACKGROUND AND PURPOSE: The embolization of aneurysms with hydrogel filaments allow postprocedural CT and MR imaging studies without artifacts. We compared the performance of 3 hydrogel filament formulations in rabbit experimental aneurysms by using angiography and histologic samples.
MATERIALS AND METHODS: Embolization of 35 rabbit elastase or bifurcation aneurysms was performed with 3 different formulations of detachable hydrogel filaments, including 1) polyethylene glycol opacified with aromatic iodine (PEG-I; n = 12), 2) polyethylene glycol opacified with barium sulfate (PEG-B; n = 12), or 3) polypropylene glycol opacified with barium sulfate (PPG-B; n = 11). Follow-up angiography was performed before the rabbits were killed at 2 (n = 7), 6 (n = 9), 10 (n = 8), or 26 (n = 11) weeks. Angiographic occlusion was scored according to the Raymond scale, and interval changes were assessed. The harvested aneurysms were evaluated on histologic examination. From the sections, we determined the percentage of the sac excluded from the vasculature and occupied by embolic devices by using image analysis. We compared results using the analysis of variancet test or 
2 test.
RESULTS: The mean number of devices used to treat aneurysms in the PPG-B group was significantly greater than that used for the other 2 groups, though aneurysm volumes were similar among groups. Compared with immediate posttreatment occlusion scores, mean angiographic occlusion at follow-up was increased for all 3 hydrogel filament groups. On histologic examination, thrombus organization, neointima formation, and inflammation were similar to that observed in rabbit experimental aneurysms with other embolic devices containing platinum coils.
CONCLUSIONS: The embolization of experimental aneurysms with hydrogel filaments resulted in durable angiographic and histologic occlusion from 2 to 26 weeks. With improvements, hydrogel filaments free from metallic coils show promise for endovascular use.