Measurement of volume ratio to predict coil compaction, on aneurysmal embolization.

The relationship between volume embolization ratio and coil compaction on the intracranial aneurysms occluded using Guglielmi detachable coils (GDCs) was determined. From March 1997 to February 1998, 38 intracranial aneurysms were embolized using GDCs. Aneurysm volume was calculated assuming that aneurysms are ellipsoids of the diameter in three planes. Coil volume was calculated assuming that detachable coils are cylinder of primary coil. Coil compaction was observed in aneurysms embolized at a volume embolization ratio under 21%. There was no coil compaction in aneurysms embolized at a volume embolization ratio of over 21%. Measurement of the volume embolization ratio is useful to predict the coil compaction. Intracranial aneurysms should be embolized at a volume embolization ratio of 25-33%.