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Significance of Volume Embolization Ratio as a Predictor of Recanalization on Endovascular Treatment of Cerebral Aneurysms with Guglielmi Detachable Coils

The purposes of this study are, firstly, to define the relationship between volume embolization ratio (VER) and degree of angiographical occlusion in endovascular treatment with Guglielmi detachable coils, and secondly, to examine influences of neck and dome sizes of aneurysms on the VER and the angiographical treatment result, and thirdly, to determine the relationship between the VER and the recanalization of coiled aneurysms. Fifty-two aneurysms in 46 patients were examined. VER ranged 8.1–31.9% (mean 18.5%). The mean VERs of each categories based on angiographical treatment results were 23.1% in complete occlusion, 16.1% in neck remnant and 12.2% in incomplete occlusion, respectively. The VER correlated significantly with both neck and dome size, while the angiographical treatment result was only affected by neck size. Five aneurysms showed aneurysmal recanalization among followed-up 41 aneurysms. All recanalized aneurysms were large, and their VERs were in range of 10.4–17.6%. Measurement of VER is useful to estimate the degree of occlusion objectively and to predict the aneurysmal recanalization. A small aneurysms with a small neck is relatively easy to achieve high VER and angiographical complete occlusion, with the consequence of less recanalization. On the other hand, a large aneurysm is liable to recanalize due to low VER, even if there was little filling of contrast medium in the aneurysmal cavity.