Background and purpose The relationship between dense packing and incidence of angiographic recurrence after endovascular treatment of intracranial aneurysms has been shown but remains controversial. We retrospectively analyzed intracranial aneurysms treated with detachable coils to determine the relation between aneurysm volume, packing, and recurrence.

Methods We reviewed 221 aneurysms in 199 patients who underwent endovascular coiling using detachable coils from November 2009 to December 2011. Aneurysm volumes were determined using three-dimensional images obtained from rotational angiography. Aneurysm packing was defined as the ratio between the volume of coils inserted and the volume of aneurysm. At follow-up, angiographic results were dichotomized into presence or absence of recurrence. The relationship between aneurysm volume to fill, packing, and angiographic recurrence was determined by multivariable logistic regression.

Results Follow-up angiography (mean follow-up 8.8 months) revealed recurrence in 14.5% of the aneurysms studied in our series. Recurrent aneurysms had a mean packing of 15.1% while stable aneurysms (non-recurrent) had a mean packing of 23.7%. Multivariable logistic regression analysis showed that aneurysm volume and packing were significantly associated with angiographic recurrence. Large volume aneurysms (>600 mm³) were found to have a higher incidence of recurrence than those with small volumes (OR=30.49, p<0.001). Compared with those with high packing (≥20%), the less packed aneurysms (<20%) had a higher incidence of recurrence (OR=29.01, p=0.002). There was no significant difference between aneurysm location, clinical presentation, stent assistance, duration of follow-up, and recurrence.

Conclusions Coiling large volume (>600 mm³) intracranial aneurysms are more likely to have a recurrence than small ones. High packing (≥20%) provides better protection against recurrence of the aneurysm.