Preliminary In Vitro Estimates of Intra-Aneurysmal Void Sizes After Endovascular Coiling

Endovascular coiling has become a well-established treatment method for cerebral aneurysms. The primary drawback of the technique is aneurysm recanalization requiring periodic angiographic follow-ups and possible aneurysm re-treatment. A recent review [1] estimates that 20% of treated aneurysms re-canalize and that half of those aneurysms (10%) are re-treated. Aneurysm recanalization is, in turn, largely caused by compaction of the coil mass due to hemodynamic impingement forces every cardiac cycle. Currently, the only quantitative measure used to characterize effectiveness of the treatment is the aneurysm packing density (ratio of total volume of coils inserted into the aneurysm and the volume of the aneurysm). Lower packing densities have been correlated with higher coil compaction rates [2], so aneurysms are generally coiled to maximal packing. A wider aneurysm neck is also correlated with higher coil-compaction rates. Coiling in such wide-neck aneurysms is performed either with the support of a balloon that is removed post-coiling or with the support of an intracranial stent that is implanted. Such assist devices also improve aneurysm packing densities [3].